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Speaker 1: Hey, Jorge, I have a pitch for a new kind

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Speaker 1: of superhero. I think we're all full up on superheroes.

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Speaker 1: I don't know, but this one, this one stayed with me,

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Speaker 1: will be scientifically accurate. So it'll be like a super physicist.

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Speaker 1: Does he happen to um you know where glasses live

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Speaker 1: in California and be called Daniel not at all? No, No,

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Speaker 1: So you've heard of Magneto, one of the X Men's,

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Speaker 1: those who can control things with magnetism. Of course, So

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Speaker 1: I was thinking, let's have a whole team of superheroes,

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Speaker 1: one for each fundamental force and have them be like accurate. Interesting,

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Speaker 1: except I vote not to be the weak force. So

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Speaker 1: there's going to be like a Gravito then, and a

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Speaker 1: strong Eto. Yeah, and Gravito would be really really really weak,

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Speaker 1: but super patient and in the end will control the

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Speaker 1: shape of the universe. Oh, the bad guys win. That's

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Speaker 1: a twist. You gotta keep the sequels coming until maybe

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Speaker 1: the week Fource gets super strong block twist. Hi'm Poor

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Speaker 1: handmy cartoonist and the creator of PhD Comics. Hi I'm Daniel.

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Speaker 1: I'm a particle physicist and a professor at UC Irvine

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Speaker 1: and I have a superpower, which is that I can

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Speaker 1: sometimes pronounce the title of my job sometimes. What kind

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Speaker 1: of superpower is that it only works in extreme situations

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Speaker 1: through like the Hulk. Well, one listener wrote in to

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Speaker 1: complain that I sometimes mispronounced the word physicist. And I'll

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Speaker 1: admit it's a tricky word. I stumble over it. Physicist, businessicist,

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Speaker 1: It's got a terrible name to it. I guess you

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Speaker 1: never have to say the word very often because you're

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Speaker 1: just surrounded by physicist all the time. Yeah, we say

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Speaker 1: the word physics a lot, but we don't call ourselves

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Speaker 1: physicists very often. You call yourself professors, I guess, explorers

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Speaker 1: of the universe. So when we're feeling grandiose, I see

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Speaker 1: he's walking to the office every day and you're like, hello,

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Speaker 1: fellow explorers of the universe, what's your plan for napping today?

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Speaker 1: Fellow nappers of the universe? Hello, fellow diviners of truth.

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Speaker 1: But you know you are a cartoonist, which means you

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Speaker 1: do cartoons. So you think, since I do physics, I

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Speaker 1: should be a physics ist. But it's not physics ist,

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Speaker 1: it's physicist. Well, English is not my first language, so

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Speaker 1: I'm not even going to pretend to know the difference.

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Speaker 1: And you know, in French, someone who does physics is

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Speaker 1: a physicist, so I think a lot of French physicists

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Speaker 1: call themselves physicians. Interesting. I wonder if people then confuse

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Speaker 1: you with real doctors. I don't real ask people to

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Speaker 1: take off their pants nearly as often. But anyway, we

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Speaker 1: welcome to our podcast. Daniel and Jorge explain the ever.

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Speaker 1: It's a production of I Heart Radio, where we are

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Speaker 1: all explorers of the universe seeking to understand the nature

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Speaker 1: of this bonker's reality, which seems to follow rules as

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Speaker 1: weird and strange as they may be. We encourage you

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Speaker 1: to join us in our journey to understand the nature

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Speaker 1: of those rules and to pick away slowly at the

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Speaker 1: mysteries that remain. Yeah, because it is a pretty mysterious universe,

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Speaker 1: full of head scratching things that happen and mysterious objects

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Speaker 1: out there that are just floating in space, begging us

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Speaker 1: to ask the question what is it? And what's going

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Speaker 1: on with you? And it's not just those of us

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Speaker 1: who can't pronounce our job titles who are curious about

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Speaker 1: the nature of the universe, wondering how the universe works

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Speaker 1: and where it came from and how it all fits

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Speaker 1: together is something almost everybody out there does. Who doesn't

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Speaker 1: want to know where the universe came from and what

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Speaker 1: its final fate will be. Yeah, because curiosity is a

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Speaker 1: very human trade. Everyone looks at the universe and wonderus.

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Speaker 1: You know, what's going on? How did that come to be?

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Speaker 1: And why are we here? And how is it that

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Speaker 1: we are here asking these questions on a podcast, and

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Speaker 1: curiosity is sort of our brand or Hey, we work

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Speaker 1: a lot on projects and encourage people to be curious,

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Speaker 1: from this podcast to our books to our TV show.

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Speaker 1: Do you ever get curious about curiosity? Like? Why are

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Speaker 1: humans so curious? Interesting? Sounds almost like the plot of

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Speaker 1: a movie that's coming out in PBS Kids pretty soon.

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Speaker 1: That sounds like a wonderful journey to me. It is.

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Speaker 1: That is the name of our special for eleanor Wonderus Fly,

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Speaker 1: which is coming out in April, so if you have kids,

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Speaker 1: but please take it out. It's a movie we wrote,

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Speaker 1: It's got awesome songs in it, and it's all about

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Speaker 1: why we ask questions, and we ask questions about the universe,

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Speaker 1: but we also want to hear about your questions. The

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Speaker 1: fact that you're listening to this podcast means that you

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Speaker 1: are curious not just about how butterfly wings evolve, but

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Speaker 1: about how space and time fit together, what we can

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Speaker 1: see at the edge of the universe, and how the

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Speaker 1: universe might fundamentally be different if we tweaked the deepest

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Speaker 1: laws of nature. So, if you are curious about how

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Speaker 1: the universe works and you have a question that you

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Speaker 1: haven't heard an inswer two please it'll be shy right

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Speaker 1: to us two questions at Daniel and Jorge dot com.

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Speaker 1: We answer everybody's questions. Yeah, because everybody has questions. This

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Speaker 1: is a very active podcast. I feel like you cannot

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Speaker 1: just listen to us talking about questions or answering questions.

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Speaker 1: You can also ask questions and you will answer them,

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Speaker 1: and sometimes we even answer them here on the podcast. Yeah,

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Speaker 1: some questions are super fun and I think other listeners

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Speaker 1: would like to hear the answer to them, or they're

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Speaker 1: a little bit tricky and I have to go read

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Speaker 1: something or think carefully about exactly how to praise the

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Speaker 1: answer because there's a lot of subtleties involved, and there's

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Speaker 1: just a lot of fun to talk about on the podcast.

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Speaker 1: Because I know that at least one person out there

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Speaker 1: wants to hear the answer. Yeah, and so today on

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Speaker 1: the podcast will be tackling listener questions. Number twenty seven

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Speaker 1: is twenty seven time we answer listening to questions, Daniel,

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Speaker 1: and I feel like maybe at this point which is

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Speaker 1: dropped the numbers and just go with like, you know,

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Speaker 1: just a fun subtitle, you know, like they do in

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Speaker 1: movies now where there are so many sequels that you

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Speaker 1: don't use. No verst listener questions, no way home and

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Speaker 1: listener questions, return listeners, strike back, listener questions, the questions awakened.

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Speaker 1: Hopefully we won't get to listen to your questions the

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Speaker 1: last question no hopefully yes? Right, but isn't that the

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Speaker 1: goal of all of physics and physicists is to get

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Speaker 1: to the last question ever know the goals to answer

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Speaker 1: today's questions, which will generate tomorrow's questions. We live for questions.

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Speaker 1: We don't want to figure everything out. We want to

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Speaker 1: continuously ask questions. Right, You just want to be able

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Speaker 1: to say your physicists forever. Today I can't say I'm

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Speaker 1: a physicist, so I'm hoping to one day figure that out.

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Speaker 1: You gotta activate that superpower. There. You got to figure

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Speaker 1: out your triggers. But yeah, we have some awesome questions

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Speaker 1: here from listeners like you and there are they're all

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Speaker 1: over the place, or about the observable universe and the

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Speaker 1: cosmic microwave background there about gravity and the forces, and

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Speaker 1: they're also about the disappearing universe. And Daniel, just to

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Speaker 1: be clear, nobody was required to take off their pants

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Speaker 1: to ask these questions. Right, we have a strict Pence

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Speaker 1: policy in this podcast. Right, I'm wearing pants. We don't

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Speaker 1: actually have a strict pants policy. So I have no idea.

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Speaker 1: I can make no statement about what pants these people

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Speaker 1: are or are not wearing. But if you'd like, in

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Speaker 1: the future, I will inquire about what people are wearing

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Speaker 1: when they record these questions. That's maybe not I think

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Speaker 1: we should be pants agnostic. Yeah, yeah, let's be pant

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Speaker 1: pant agnostic. Yeah, alright, well let's jump into it. Our

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Speaker 1: first question here comes from Jeff, and Jeff has a

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Speaker 1: question about the observable universe and the cosmic microwave background. Hi, Daniel,

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Speaker 1: Jorge and special guests contributors. I'm Jeff from Alltown, p A.

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Speaker 1: If the observable universe extends only as far as light

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Speaker 1: as that time to reach us, and that faston the

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Speaker 1: light expansion precludes us from ever seeing galaxies beyond. How

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Speaker 1: is it we can still image the cosmic microwave background,

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Speaker 1: which should predate any cosmic structures. Thank you again for

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Speaker 1: keeping us educated, wondering, curious, and entertained. Awesome. Thank you

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Speaker 1: Jeff for that question, and a shout out to Allentown, Pennsylvania. Daniel.

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Speaker 1: I feel like Jeff asked a pretty good gotcha question,

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Speaker 1: Like I'm wondering how we're going to answer this one.

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Speaker 1: Jeff has a question which really exposes a lot of

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Speaker 1: subtle issues in understanding how far we can see in

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Speaker 1: the universe as the universe is expanding, and as that

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Speaker 1: expansion is accelerating, and so there are a couple of

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Speaker 1: interesting issues here, like what is the oldest thing we

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Speaker 1: can see? And what is it that we cannot see

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Speaker 1: in the universe? Right right, There's a lot of sort

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Speaker 1: of concepts here in this question, Like, first of all,

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Speaker 1: it's the idea of the observable universe. Then also the

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Speaker 1: expansion of the universe, which is presumably maybe at some

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Speaker 1: point going faster than light, and then there's also the

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Speaker 1: concept of the cosmic microwave background, which is kind of

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Speaker 1: like the revenant light from The Big Bang exactly. And

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Speaker 1: so the basic concept to understand is that as we

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Speaker 1: look further and further away, we're seeing things that are

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Speaker 1: older and older. We're looking back in time, and that's

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Speaker 1: just because it takes time for light to get to

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Speaker 1: us from Earth. So we're looking at a distant star

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Speaker 1: that's really far away. We're not seeing it as it

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Speaker 1: is today. We're seeing it as it was when that

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Speaker 1: light left it, and it doesn't look like that today,

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Speaker 1: and it's probably in a different location today. And so

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Speaker 1: as we look further away, we see further back in time,

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Speaker 1: which is actually super awesome and really useful for doing

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Speaker 1: science because we get to see the history of the universe,

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Speaker 1: not just the way it looks today. Right. Yeah, And

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Speaker 1: the whole reason is that light takes a while to

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Speaker 1: get two places. Right, Like, light isn't infinitely fast. It

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Speaker 1: has the speed of light and it's a it's limited,

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Speaker 1: and so space is so big that there's still stuff

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Speaker 1: like coming at us, like coming at us that started

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Speaker 1: maybe billions and billions of years ago. That's right. There

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Speaker 1: are f photons arriving today that left their location billions

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Speaker 1: can imagine, like our past light cone. You know, things

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Speaker 1: arriving right now, and things that were really far away

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Speaker 1: order to reach us right now. But those two photons

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Speaker 1: can be arriving at the same moment from different locations

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Speaker 1: and also different times in the past. Yeah, and it's

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Speaker 1: sort of coming at us from all directions, which is

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Speaker 1: which makes it more of a bubble, right than a

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Speaker 1: cone kind of right, it's more of like a bubble

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Speaker 1: around us, which is as far as we can see,

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Speaker 1: because anything further the light just hasn't reached us. Yeah.

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Speaker 1: In one dimensions, it would be like a light triangle,

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Speaker 1: and two dimensions would be like a light cone. But

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Speaker 1: you're right, in three dimensions, it's sort of harder to imagine.

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Speaker 1: It's like a conoid. It would be the geometrical term.

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Speaker 1: I think you need a superpower just to pronounce that. There.

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Speaker 1: And so as we look further back in time, we're

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Speaker 1: looking further into the past, and so we can see,

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Speaker 1: for example, how Gala seas formed. We can see things

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Speaker 1: that happened a billion years after the Big Bang, we

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Speaker 1: can see things that happened five million years after the

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Speaker 1: Big Bang. We can keep looking further and further back

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Speaker 1: in time, right, And so there's this sort of bubble

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Speaker 1: around us of things we can see. But also at

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Speaker 1: the same time, the universe is expanding, so the bubble

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Speaker 1: and the things in it are sort of flying away

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Speaker 1: from us, or at least getting stretched away from us,

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Speaker 1: which is kind of makes it tricky, right, It does

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Speaker 1: make it tricky. The whole thing is pretty complicated and

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Speaker 1: hard to hold in your head. First, let's imagine the

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Speaker 1: universe was not expanding. Then, you know, the bubble we

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Speaker 1: could see would be growing as time went on, and

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Speaker 1: we have no problem seeing the cosmic marcrowave background. We

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Speaker 1: could see things before structure formed. Right, You don't have

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Speaker 1: to see a galaxy in order to see stuff. You

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Speaker 1: just need to see light. So the cosmic microwave background

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Speaker 1: is light from the first plasma before structure was formed.

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Speaker 1: When the universe became transparent. We can't really see before

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Speaker 1: that because the universe was opaque, but we can see

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Speaker 1: past the earliest galaxies all the way to the cosmic

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Speaker 1: microwave background radiation. Right, So that's if the universe was

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Speaker 1: not expanding. Now Jeff says, well, the universe is expanding,

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Speaker 1: and it's expanding fast in the light, which means some

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Speaker 1: parts of the universe we will never see. And he's right.

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Speaker 1: There are things that are so distant past, like sixty

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Speaker 1: five billion light years, where the light will never reach

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Speaker 1: us because the universe is expanding. As we'd like to say,

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Speaker 1: you know, if Hussain Bolt is running towards you and

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Speaker 1: somebody's laying track in front of him faster than he's running,

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Speaker 1: he's never going to get to you. So there are

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Speaker 1: photons moving at us, but they're moving through parts of

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Speaker 1: the universe that are receding fast in the speed of light,

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Speaker 1: so they will never reach us. Right. It's like we

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Speaker 1: can see this bubble around us, but there's also sort

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Speaker 1: of another bubble that's maybe bigger than that of stuff

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Speaker 1: we haven't seen yet. And then we'll also never see

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Speaker 1: because at the same time that we're seeing this bubble,

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Speaker 1: space is expanding, and so there's maybe stuff out there

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Speaker 1: beyond the bubble we can see that may we'll never see, right,

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Speaker 1: because it's moving it too fast. That's right. The current

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Speaker 1: edge of the observable universe is forty six billion light

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Speaker 1: years away, but there's another edge sixty three billion light

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Speaker 1: years away, and stuff beyond that we will never see, Like,

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Speaker 1: it doesn't matter how long you wait, we will never

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Speaker 1: see it because the universe is expanding so fast that

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Speaker 1: those photons will always be moving through space that's moving

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Speaker 1: away from us faster than the speed of light, and

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Speaker 1: so we would just never see it, assuming, of course,

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Speaker 1: the current cosmological model is correct and that expansion continues

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Speaker 1: in the same way that it does. But then Jeff's

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Speaker 1: question is, so, then how is it possible to see

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Speaker 1: the CNB If there are parts of the universe that

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Speaker 1: are moving away from us so fast, we'll never see them, right, Yeah,

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Speaker 1: that's kind of mind blowing to think about. Like, at

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Speaker 1: sixty five billion light years, there's like a son right

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Speaker 1: there that's shining and it's throwing a photon at us,

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Speaker 1: but that photon is like sort of fighting against the

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Speaker 1: stretching of space and just will never get to us.

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Speaker 1: That's right. It's moving through its space at the speed

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Speaker 1: of light, but the distance between us and that photon

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Speaker 1: is actually increasing. Right, The proper stance between us and

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Speaker 1: that photon is growing even though it's moving through space

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Speaker 1: towards us, right, because space in front of it is expanding.

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Speaker 1: It's like there's news space growing between us and that

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Speaker 1: photon rate that's higher than three hundred million meters per second. Right.

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Speaker 1: And if we were relying on seeing light from the

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Speaker 1: CNB that came from super far away cosmic marketway background plasma,

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Speaker 1: then Jeff is right, we would never be able to

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Speaker 1: see it. What we are seeing when we look at

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Speaker 1: the CNB is not light that was emitted from that

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Speaker 1: far away. It was actually emitted from pretty close to us.

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Speaker 1: It's just taken forever to get here because the universe

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Speaker 1: has expanded while those photons fly through the universe. Right.

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Speaker 1: I think maybe what Jeff is thinking is that, you know,

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Speaker 1: there is a background of like light that came from

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Speaker 1: the Big Bang, And you know the word background means

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Speaker 1: like it's in the back, right, So he's probably manna

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Speaker 1: be thinking that this cosmic background comes from like way

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Speaker 1: further out, like since the further out we look, the

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Speaker 1: further back in time we look. He's thinking maybe the

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Speaker 1: source of this light is like the you know, the

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Speaker 1: basically the background of the universe, and so he's wondering, like,

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Speaker 1: if the background is moving away from us faster than light,

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Speaker 1: then how can that background get to us? But you're saying,

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Speaker 1: I think, is that it's not really like in the back,

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Speaker 1: it's like everywhere. It is, in fact, everywhere the CNB

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Speaker 1: was admitted everywhere. There's a patch of the universe where

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Speaker 1: we are right now. There used to be plasma right here,

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Speaker 1: and it emitted CNB light, and that CNB light is

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Speaker 1: flying away from us, and it's been flying away from

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Speaker 1: us fo the whole universe, and it's now almost forty

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Speaker 1: six billion light years away right, not exactly forty six

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Speaker 1: billion light years, because it was admitted a little bit

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Speaker 1: after the universe started, like you know, a few hundred

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Speaker 1: thousand light years. And similarly, the CNB light that we

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Speaker 1: are seeing right now was emitted from stuff which is

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Speaker 1: now almost at the edge of the observable universe, right,

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Speaker 1: so it did have time to get here. It's within

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Speaker 1: the edge of the observable universe. Interestingly, though, when it

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Speaker 1: admitted it, it was much much closer, like it was

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Speaker 1: probably only a few tens of millions of light years

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Speaker 1: away when it emitted that light. But the universe has

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Speaker 1: been expanding so much that took thirteen billion years to

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Speaker 1: cross what was originally forty two million light years, right.

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Speaker 1: The same mystery for the stars that are at that business, right,

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Speaker 1: like the library getting from the edge of the servile universe,

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Speaker 1: is from stars that they used to be closer to us. Exactly.

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Speaker 1: So the patch of the universe which now occupies like

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Speaker 1: a sphere with radius forty six billion light years, used

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Speaker 1: to be much much smaller. At the universe is expanding rapidly,

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Speaker 1: and so basically we are seeing what used to be

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Speaker 1: a tiny little bubble of the universe. Something which was

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Speaker 1: fifty million light years away from us at the very

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Speaker 1: beginning of the universe is now outside the edge of

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Speaker 1: the observable universe. Will probably never see it because it's

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Speaker 1: all expanded. So the CNB light we're seeing today started

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Speaker 1: out forty two million light years away, has been struggling

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Speaker 1: to get to us for billions of years, and has

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Speaker 1: now just arrived. We see it today, and we think

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Speaker 1: the plasma that admitted it that stuff is now forty

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Speaker 1: six billion light years away, right. I think that maybe

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Speaker 1: the key point here is that the cosmic microwave background

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Speaker 1: was sort of like made everywhere in all directions at

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Speaker 1: the same time, you know, Like it wasn't like one

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Speaker 1: event that flashed and then now the light is getting

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Speaker 1: to us. It's like even where we are right now,

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Speaker 1: like this batch of space that I'm occupying here in

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Speaker 1: my podcast studio, like this space around me generated some

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Speaker 1: microwave background radiation at some point in the past, but

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Speaker 1: now that light has just gone right. It's like it's

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Speaker 1: when when, and in all directions. But the same thing

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Speaker 1: happened all over space, like between here and the observable

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Speaker 1: universe the edge of it. There was stuff being generated

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Speaker 1: at every point. Yeah, And I think a lot of

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Speaker 1: people have a misconception that the universe started as a

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Speaker 1: point and then expanded and at some moment it was

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Speaker 1: this little ball of plasma that admitted that light, and

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Speaker 1: they wonder, like, why is it we can see it

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Speaker 1: right now, and you're write the answer is that that's true.

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Speaker 1: But it wasn't just a little ball. The whole univer

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Speaker 1: verse was filled with this plasma. The big band wasn't

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Speaker 1: just when one spot, it was everywhere, and so everywhere

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Speaker 1: in the universe had these little balls of plasma. And

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Speaker 1: as time goes on, we continue to see the CMB,

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Speaker 1: but we see different slices of it. We see light

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Speaker 1: from different pieces of that infinite universe plasma. Right, I

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Speaker 1: wonder if I have a good analogy, is kind of

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Speaker 1: like a rubber band, Like if you're stretching a rubber band,

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Speaker 1: but also all of the rubber band was emitting light.

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Speaker 1: You would see the light that your patch of space emitted,

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Speaker 1: and you're part of the rubber band, but you also

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Speaker 1: over time be seeing the light those generated over other

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Speaker 1: parts of the rubber band. Yeah, and if you think

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Speaker 1: about what's going to happen in a very very far future,

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Speaker 1: we will always see some CMB, but you know, there

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Speaker 1: is a limit of what fraction of the universe we

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Speaker 1: will see. So eventually the CNB will just get red

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Speaker 1: shifted into invisibility. Like the CNB right now is very

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Speaker 1: long wavelengths compared to the light that was emitted at

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Speaker 1: the time. It used to be a very hot plasma

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Speaker 1: hundreds of thousands of degrees. It used to be you know,

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Speaker 1: very high frequent and see wavelength, and it's gotten red

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Speaker 1: shifted down to very long wavelengths, down to like two

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Speaker 1: point seven degrees Calvin. So that's just going to keep happening.

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Speaker 1: The wavelength is gonna get longer and longer until eventually

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Speaker 1: becomes essentially invisible. Right, And I think what's interesting what

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Speaker 1: you just said is that you know, the cosmic microwave background,

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Speaker 1: then we'll be changing over the next couple of billion years,

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Speaker 1: like the picture of it is gonna wiggle and ripple

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Speaker 1: because it's coming from different parts of the universe each

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Speaker 1: time you take the picture exactly, and so as we

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Speaker 1: look at it it does change that it doesn't change

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Speaker 1: very rapidly. Um. You know, we took the original picture

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Speaker 1: of the CNB thirty years ago, and then we're taking

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Speaker 1: more and more refined pictures of it, and over those

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Speaker 1: time periods it doesn't really change in any significantly observable way.

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Speaker 1: So we are seeing slightly different slices of the universe.

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Speaker 1: But you know, in the way that like a star

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Speaker 1: doesn't change very much when you look at it from

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Speaker 1: one year to the next. On these time scales of

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Speaker 1: twenty thirty years, nothing really is changing. If we keep

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Speaker 1: watching it for millions and billions of years and keep

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Speaker 1: doing astronomy for that long and then we will see

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Speaker 1: different slices of the universe. M M. Yeah, And I

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Speaker 1: think Jeff is right that at some point in the future,

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Speaker 1: like the observable universe is going to reach the point

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Speaker 1: where we can't see anything, including the cosmic microwave background. Right, Like,

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Speaker 1: at some point in the future, um, this cosmic microwave

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Speaker 1: is going to disappear. I think we'll always be able

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Speaker 1: to see some CNB, but it will just red shift

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Speaker 1: away to infinity. There's always going to be some point

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Speaker 1: in the universe where light is just now arriving from

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Speaker 1: wherever it was admitted. And since the CNB was everywhere

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Speaker 1: in the universe, there will always be some CNB whose

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Speaker 1: light is just now arriving. But that's going to get

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Speaker 1: more and more stretched out as time goes on, and

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Speaker 1: eventually you'll disappear, right, let's get stretched into nothingness. Oh yes,

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Speaker 1: it disappear in the sense that the wavelength will reach

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Speaker 1: infinity and therefore it be like essentially unobservable. Like if

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Speaker 1: the CNB has a wavelength of the galaxy, then you

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Speaker 1: need a galaxy size detector to see it, and so yeah,

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Speaker 1: it would be invisible to us MM, so it will

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Speaker 1: sort of disappear, So like if humans had come around,

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Speaker 1: may be a couple of billion years later, whichever alien

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Speaker 1: species comes up a few billion years from now may

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Speaker 1: not maybe even be able to see this kind of

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Speaker 1: baby picture of the universe. Yeah, And whenever I think

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Speaker 1: about that, I realized it's lucky that we live now

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Speaker 1: so we can sort of see this stuff in the universe.

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Speaker 1: It makes me wonder what used to be observable in

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Speaker 1: the universe five billion years ago that now we will

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Speaker 1: never see and couldn't discover. What pictures are we missing?

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Speaker 1: What clues? Will we never get to the deep nature

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Speaker 1: of the universe because we came along fourteen billion years

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Speaker 1: after the party started. Yeah, we missed the cosmic microwave

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Speaker 1: foreground because we got here too late. We procrastinated Daniel

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Speaker 1: in our evolution. We shouldn't have spend so much time

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Speaker 1: in the primordial sludge. Yeah, it was pretty warm and cozy.

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Speaker 1: I gotta say, all right, Well that answers the question

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Speaker 1: for Jeff Um. You're right, the same bee will disappear

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Speaker 1: one day, but not for a while because we are

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Speaker 1: still seeing it and because it was generated by every

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Speaker 1: point in space. All right, let's get into our next question, Um,

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Speaker 1: this one is about gravity, magnetism and the different forces.

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Speaker 1: So we'll get to that, but first let's take a

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Speaker 1: quick break. Al Right, we are answering listener questions. Today.

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Speaker 1: We talked about a great question about the server universe

429
00:22:25,520 --> 00:22:27,879
Speaker 1: and the cosmic microwave background, and now we have a

430
00:22:28,000 --> 00:22:30,399
Speaker 1: question here about the forces. And this is kind of

431
00:22:30,440 --> 00:22:33,800
Speaker 1: what you're referencing before, Daniel, about superheroes based on the

432
00:22:33,800 --> 00:22:37,200
Speaker 1: different forces, because we have different forces in the universe. Yeah,

433
00:22:37,240 --> 00:22:39,240
Speaker 1: we have these different forces in the universe, and we

434
00:22:39,280 --> 00:22:42,240
Speaker 1: don't understand why some of them are stronger than others

435
00:22:42,280 --> 00:22:43,960
Speaker 1: and some of them are weaker. And we think that

436
00:22:44,080 --> 00:22:46,760
Speaker 1: maybe in the early universe they might have all been

437
00:22:46,840 --> 00:22:51,480
Speaker 1: one force that had one strength, but we're not sure. Interesting,

438
00:22:51,520 --> 00:22:54,680
Speaker 1: we had the Avengers before The Avengers was the prequel.

439
00:22:55,520 --> 00:22:57,479
Speaker 1: It's sort of like, you know, how the Power Rangers

440
00:22:57,520 --> 00:23:01,080
Speaker 1: can come together into one superpower Ranger. Uh huh, we

441
00:23:01,119 --> 00:23:04,119
Speaker 1: think the reverse might have happened in our universe. Interesting,

442
00:23:04,200 --> 00:23:06,119
Speaker 1: it's a prequel. All right. Well, then let's get to

443
00:23:06,119 --> 00:23:09,000
Speaker 1: the question. This one is from on God who wonders

444
00:23:09,000 --> 00:23:12,760
Speaker 1: about gravity and magnetism. Hi, Daniel and Jorge really like

445
00:23:12,880 --> 00:23:17,240
Speaker 1: your podcast because it teaches so much about physics in space.

446
00:23:17,960 --> 00:23:22,000
Speaker 1: So I got me. I'm wondering what would happen if

447
00:23:22,080 --> 00:23:27,199
Speaker 1: gravity was as strong as magnetism would So, if the

448
00:23:27,280 --> 00:23:31,919
Speaker 1: universe started with gravity being as strong as magnetism, what

449
00:23:32,080 --> 00:23:36,880
Speaker 1: would happen? Would the universe even start expanding or not?

450
00:23:37,000 --> 00:23:40,840
Speaker 1: Or were it get even donser somehow? Also, what would

451
00:23:40,880 --> 00:23:45,280
Speaker 1: happen if right now, if the universe is normal, but

452
00:23:45,359 --> 00:23:50,240
Speaker 1: then right now gravity all of a sudden becomes as

453
00:23:50,240 --> 00:23:54,600
Speaker 1: strong as magnetism, where it create mega black holes and

454
00:23:54,640 --> 00:23:58,440
Speaker 1: then things that are so done that time goes backwards.

455
00:23:58,920 --> 00:24:02,160
Speaker 1: But the bending of the like cone? What would happen?

456
00:24:02,440 --> 00:24:05,480
Speaker 1: Thank you very much, good luck with the podcast. Oh man,

457
00:24:05,560 --> 00:24:07,679
Speaker 1: what an awesome question. Thank you on God you do?

458
00:24:07,680 --> 00:24:09,560
Speaker 1: You have so much going on in your in your

459
00:24:09,640 --> 00:24:13,960
Speaker 1: little head. That's amazing. That is a future physicist for sure. Yeah,

460
00:24:14,040 --> 00:24:16,040
Speaker 1: let's get him practicing the how to say the word

461
00:24:16,040 --> 00:24:20,600
Speaker 1: physicists as soon as possible. Clearly not a prove requisite, however,

462
00:24:20,640 --> 00:24:24,800
Speaker 1: for becoming one. So maybe it should be Danny should

463
00:24:24,800 --> 00:24:28,280
Speaker 1: be pants essential pronunciation, not necessarily. I mean, how are

464
00:24:28,320 --> 00:24:30,399
Speaker 1: you going to recruit more of you if you can't

465
00:24:30,400 --> 00:24:34,040
Speaker 1: even say the word. So you're saying we should have

466
00:24:34,119 --> 00:24:37,480
Speaker 1: more physicists in the world. I'm saying you should have

467
00:24:37,520 --> 00:24:40,280
Speaker 1: more trained physicists. And how to pronounce your job title.

468
00:24:41,680 --> 00:24:46,080
Speaker 1: It's all about priorities. Yeah, but their question is pretty interesting, uh,

469
00:24:46,119 --> 00:24:48,560
Speaker 1: And it's about the forces. So the main question is

470
00:24:49,280 --> 00:24:52,480
Speaker 1: what if gravity was as strong as magnetism? And so

471
00:24:52,560 --> 00:24:55,960
Speaker 1: gravity is one force, magnetism is another force. And actually

472
00:24:55,960 --> 00:25:00,240
Speaker 1: gravity you always say is very weak compared to magnetism. Yeah,

473
00:25:00,320 --> 00:25:04,800
Speaker 1: gravity is the weakest of the forces by a long shot,

474
00:25:04,880 --> 00:25:07,080
Speaker 1: like not by a tiny little bit or a factor

475
00:25:07,119 --> 00:25:10,119
Speaker 1: of ten, but by a factor of ten to the

476
00:25:10,240 --> 00:25:13,439
Speaker 1: thirties seven. You know, like a billion is ten with

477
00:25:13,520 --> 00:25:16,320
Speaker 1: twelve zeros in front of it. This is ten with

478
00:25:16,560 --> 00:25:19,879
Speaker 1: thirty seven zeros in front of it. It's really a

479
00:25:19,960 --> 00:25:22,000
Speaker 1: huge number. They're just like not even on the same

480
00:25:22,000 --> 00:25:25,600
Speaker 1: playing field at all. Yeah, Like magnetism is the thirty

481
00:25:25,640 --> 00:25:28,639
Speaker 1: seven orders of magnitude stronger than gravity, meaning like if

482
00:25:28,680 --> 00:25:31,359
Speaker 1: you have two things that have mass and electric charge,

483
00:25:31,640 --> 00:25:33,960
Speaker 1: like the force they feel because of the electric charge

484
00:25:34,040 --> 00:25:37,040
Speaker 1: is much much higher. Yeah, and you're using electric charge

485
00:25:37,080 --> 00:25:39,600
Speaker 1: there because you know that magnetism is actually part of

486
00:25:39,640 --> 00:25:44,200
Speaker 1: a unified idea of electro magnetism. Magnetism by itself isn't

487
00:25:44,240 --> 00:25:47,639
Speaker 1: really a holistic concept. You need electricity to understand it

488
00:25:47,680 --> 00:25:50,600
Speaker 1: as well. And that's because from different like frames of reference,

489
00:25:50,840 --> 00:25:54,080
Speaker 1: the same phenomena will produce electricity or magnetism. So really

490
00:25:54,080 --> 00:25:57,120
Speaker 1: it's one holistic concept we talk about. And as you say,

491
00:25:57,240 --> 00:26:00,800
Speaker 1: magnetism is much much stronger than gravity. And you can

492
00:26:00,920 --> 00:26:03,560
Speaker 1: discover this yourself in your kitchen. You know, you have

493
00:26:03,680 --> 00:26:05,800
Speaker 1: kitchen magnets on your fridge, right, and they stick to

494
00:26:05,800 --> 00:26:08,560
Speaker 1: your fridge. They don't fall down, even though the entire

495
00:26:08,680 --> 00:26:11,639
Speaker 1: mass of the Earth, right, the whole planet is tugging

496
00:26:11,680 --> 00:26:14,200
Speaker 1: on them. And yet a tiny kitchen magnet can totally

497
00:26:14,240 --> 00:26:18,920
Speaker 1: resist that because magnetism is that much more powerful than gravity. Yeah,

498
00:26:19,000 --> 00:26:21,639
Speaker 1: Like the kitchen magnet is being pulled towards the Earth

499
00:26:21,680 --> 00:26:25,280
Speaker 1: by the whole earth gravity, but it's being pulled up

500
00:26:25,320 --> 00:26:28,720
Speaker 1: by its magnetic attraction to the fridge. Yeah. I like

501
00:26:28,760 --> 00:26:30,520
Speaker 1: to think that every time I get up in the morning,

502
00:26:30,520 --> 00:26:35,679
Speaker 1: I'm beating the whole Earth. That's right. Bananas apparently are

503
00:26:35,720 --> 00:26:38,840
Speaker 1: more powerful than the Earth. You can defeat its gravity.

504
00:26:39,200 --> 00:26:41,240
Speaker 1: Yea banana and cereal, they'll get me up in the

505
00:26:41,280 --> 00:26:44,480
Speaker 1: morning every day, and it beats gravity. And the other

506
00:26:44,520 --> 00:26:47,879
Speaker 1: forces are also not equal, right. The strong force is

507
00:26:47,880 --> 00:26:51,920
Speaker 1: a hundred and thirties seven times more powerful than electromagnetism,

508
00:26:52,000 --> 00:26:54,760
Speaker 1: which is even more powerful than the weak force. But

509
00:26:54,920 --> 00:26:57,480
Speaker 1: all of those are basically the same compared to gravity,

510
00:26:57,480 --> 00:27:00,879
Speaker 1: which is almost zero compared to the other forces. And

511
00:27:00,960 --> 00:27:04,199
Speaker 1: yet gravity is the one that dominates the structure of

512
00:27:04,200 --> 00:27:06,399
Speaker 1: the universe, right. The nature of the Solar System, the

513
00:27:06,440 --> 00:27:09,800
Speaker 1: shape of galaxies, all that is because of gravity. And

514
00:27:09,840 --> 00:27:11,359
Speaker 1: that's because there is a lot of mass in the

515
00:27:11,440 --> 00:27:15,360
Speaker 1: universe and gravity is very, very patient, and eventually it wins. Yeah.

516
00:27:15,400 --> 00:27:17,399
Speaker 1: And the main reason, I know we've talked about this

517
00:27:17,480 --> 00:27:19,840
Speaker 1: before is that for the other forces, they sort of

518
00:27:19,960 --> 00:27:23,240
Speaker 1: cancel each other out. Like there's a plus you know,

519
00:27:23,359 --> 00:27:25,760
Speaker 1: a magnetic force and a negative magnetic force, and if

520
00:27:25,760 --> 00:27:28,080
Speaker 1: you're a plus charge or minus charge, you would feel

521
00:27:28,080 --> 00:27:31,440
Speaker 1: one of them. But because they're able to cancel, they

522
00:27:31,480 --> 00:27:34,840
Speaker 1: sort of cancel out generally in the universe. But gravity,

523
00:27:35,119 --> 00:27:37,720
Speaker 1: it's always attracting. Yeah, Gravity, if you think about in

524
00:27:37,800 --> 00:27:40,399
Speaker 1: terms of a force rather than the curvature of space time,

525
00:27:40,840 --> 00:27:43,840
Speaker 1: it's basically just got one kind of charge, right, mass

526
00:27:43,920 --> 00:27:45,760
Speaker 1: is always positive, and so all it can do is

527
00:27:45,760 --> 00:27:49,639
Speaker 1: attract the other forces as you say it, positives and negatives,

528
00:27:49,760 --> 00:27:52,080
Speaker 1: or you know, the strong force has three different kinds

529
00:27:52,119 --> 00:27:54,840
Speaker 1: of color, but they can be balanced out. You can

530
00:27:54,880 --> 00:27:57,920
Speaker 1: get things that are effectively neutral. It's impossible to get

531
00:27:57,960 --> 00:28:02,160
Speaker 1: everything neutral gravitationally, unless you like spread everything out through

532
00:28:02,200 --> 00:28:05,760
Speaker 1: the universe totally homogeneously. There will always be a gravitational

533
00:28:05,800 --> 00:28:08,960
Speaker 1: force that tugs on things, so eventually gravity will wait,

534
00:28:09,000 --> 00:28:11,159
Speaker 1: it will pull everything into a black hole, right. I

535
00:28:11,160 --> 00:28:12,800
Speaker 1: think we covered this in our book or one of

536
00:28:12,800 --> 00:28:16,160
Speaker 1: our books, where like if the whole Earth was positively

537
00:28:16,240 --> 00:28:19,480
Speaker 1: charged and the whole Sun was negatively charged, like we'd

538
00:28:19,480 --> 00:28:22,960
Speaker 1: be toasts, Like the whole Earth would just fly into

539
00:28:22,960 --> 00:28:27,639
Speaker 1: the Sun super fast, because that's how strong the electroplanknetic forces.

540
00:28:27,720 --> 00:28:30,000
Speaker 1: But because you know, we have an equal number of

541
00:28:30,040 --> 00:28:33,560
Speaker 1: plus and minus force charges here on Earth and almost

542
00:28:33,640 --> 00:28:36,119
Speaker 1: equal mound in the Sun like to the Earth, the

543
00:28:36,119 --> 00:28:39,960
Speaker 1: Sun is neutral. It doesn't feel any electromagnetic attraction or

544
00:28:40,040 --> 00:28:43,040
Speaker 1: repulsion exactly. And the reason is that mostly the universe

545
00:28:43,120 --> 00:28:47,280
Speaker 1: was formed from neutral stuff because electromagnetism is so strong

546
00:28:47,720 --> 00:28:51,200
Speaker 1: that charged particles sought each other out to balance each

547
00:28:51,240 --> 00:28:53,920
Speaker 1: other out early on in the universe, and so the

548
00:28:54,000 --> 00:28:57,760
Speaker 1: universe neutralized from the point of view of electromagnetism, long

549
00:28:57,800 --> 00:29:01,000
Speaker 1: before gravity really had anything to say about anything. Yeah,

550
00:29:01,080 --> 00:29:03,800
Speaker 1: and so I'm guess question is that gravity is weaker

551
00:29:03,840 --> 00:29:06,520
Speaker 1: than the electromagnetic force. But what if it wasn't, Like,

552
00:29:06,640 --> 00:29:09,400
Speaker 1: what if it was stronger at the beginning of time?

553
00:29:09,480 --> 00:29:11,800
Speaker 1: And what would happen if it suddenly got stronger? And

554
00:29:11,880 --> 00:29:14,239
Speaker 1: now it's a great question, and I love running these

555
00:29:14,240 --> 00:29:17,000
Speaker 1: sort of mental simulations, like what would the universe look

556
00:29:17,040 --> 00:29:19,680
Speaker 1: like if the knobs were different? And it's a really

557
00:29:19,680 --> 00:29:22,600
Speaker 1: important question because let's just think about, like, why are

558
00:29:22,640 --> 00:29:24,800
Speaker 1: the knobs set the way they are? Is it possible

559
00:29:24,840 --> 00:29:27,440
Speaker 1: they could have been set differently or not? And so

560
00:29:27,600 --> 00:29:31,720
Speaker 1: in this case, if gravity was just as strong as electromagnetisms,

561
00:29:31,720 --> 00:29:34,880
Speaker 1: so we're cranking gravity up by ten to the thirty seven,

562
00:29:35,360 --> 00:29:37,600
Speaker 1: then the whole universe would look very different from the

563
00:29:37,680 --> 00:29:40,200
Speaker 1: very beginning. Remember that the structure of the universe that

564
00:29:40,520 --> 00:29:43,320
Speaker 1: we see now galaxies and stars and planets and all

565
00:29:43,360 --> 00:29:46,680
Speaker 1: this stuff, took a long time to form because gravity

566
00:29:46,760 --> 00:29:48,840
Speaker 1: is so weak. So gravity was sort of on the

567
00:29:48,920 --> 00:29:52,520
Speaker 1: sidelines while the universe was cooling, and all these particles

568
00:29:52,560 --> 00:29:55,720
Speaker 1: buzzing around positive negative charges. The universe cools and the

569
00:29:55,760 --> 00:29:58,600
Speaker 1: other forces are sort of in charge. So the strong force,

570
00:29:58,640 --> 00:30:01,160
Speaker 1: for example, pulls together a bunch of quarks to make

571
00:30:01,240 --> 00:30:03,560
Speaker 1: them neutral from the strong force point of view. So

572
00:30:03,600 --> 00:30:05,960
Speaker 1: you get like protons, right, which are neutral from the

573
00:30:06,000 --> 00:30:09,080
Speaker 1: strong force. And then electromagnetism takes over and it pulls

574
00:30:09,120 --> 00:30:13,080
Speaker 1: protons and electrons together to make neutral atoms like hydrogen.

575
00:30:13,360 --> 00:30:17,640
Speaker 1: And then finally, thousands and millions of years later, gravity

576
00:30:17,760 --> 00:30:21,040
Speaker 1: does its job and clumps those together into stars. Now,

577
00:30:21,040 --> 00:30:24,520
Speaker 1: if gravity was as strong as electromagnetism, then it would

578
00:30:24,520 --> 00:30:26,640
Speaker 1: have been active much earlier on. It wouldn't have been

579
00:30:26,640 --> 00:30:30,000
Speaker 1: waiting while electromagnetism form neutral atoms. It would have started

580
00:30:30,040 --> 00:30:33,680
Speaker 1: clumping protons together before they even neutralized. You would get

581
00:30:33,680 --> 00:30:37,400
Speaker 1: these like huge positively charged masses. Well, I guess you

582
00:30:37,440 --> 00:30:39,480
Speaker 1: have to be clear, Like, it's not like gravity turn

583
00:30:39,600 --> 00:30:42,120
Speaker 1: on at toping, Like it was always there from the beginning.

584
00:30:42,320 --> 00:30:44,520
Speaker 1: It was just so weak compared to the electroc bannetic

585
00:30:44,600 --> 00:30:47,480
Speaker 1: corps that basically the universe sort of egbarded for a

586
00:30:47,480 --> 00:30:49,920
Speaker 1: long time. Exactly. It was irrelevant for a long time

587
00:30:49,960 --> 00:30:53,120
Speaker 1: because more powerful forces were on the field. Only when

588
00:30:53,120 --> 00:30:56,960
Speaker 1: those forces finished doing their jobs could gravity even play

589
00:30:57,040 --> 00:30:59,560
Speaker 1: in the game, because it was the only thing left

590
00:30:59,560 --> 00:31:02,240
Speaker 1: on the fee basically, And so if gravity was much

591
00:31:02,320 --> 00:31:05,040
Speaker 1: much stronger than it would have been relevant earlier on

592
00:31:05,560 --> 00:31:08,480
Speaker 1: and hydrogen, for example, might not have formed in the

593
00:31:08,560 --> 00:31:12,120
Speaker 1: same way because gravity would have like tugged all those

594
00:31:12,160 --> 00:31:15,959
Speaker 1: protons together instead of letting them seek out their electrons.

595
00:31:16,040 --> 00:31:18,160
Speaker 1: And I don't want to overstate it, as you say,

596
00:31:18,360 --> 00:31:21,080
Speaker 1: gravity is around, and even though it's weaker than the

597
00:31:21,120 --> 00:31:24,120
Speaker 1: other forces, it does play a role in the early universe.

598
00:31:24,160 --> 00:31:26,720
Speaker 1: We can see its effect on like the slashing of

599
00:31:26,720 --> 00:31:29,920
Speaker 1: the barry on plasma. It just wasn't dominant, right or

600
00:31:29,960 --> 00:31:32,920
Speaker 1: I wonder if even like neutrons or protons would have formed,

601
00:31:32,920 --> 00:31:34,800
Speaker 1: like could gravity somehow mess up with the way the

602
00:31:34,920 --> 00:31:37,840
Speaker 1: quarks like buying together could potentially if it was strong enough.

603
00:31:37,920 --> 00:31:41,920
Speaker 1: In this scenario, though, gravity is as strong as electromagnetism,

604
00:31:42,040 --> 00:31:44,120
Speaker 1: which is weaker than the strong force, So then in

605
00:31:44,120 --> 00:31:47,240
Speaker 1: this scenario the strong force would still be stronger than gravity,

606
00:31:47,320 --> 00:31:49,720
Speaker 1: so you would still form protons of course, would feel

607
00:31:49,880 --> 00:31:53,320
Speaker 1: those color forces more strongly than they would feel gravity,

608
00:31:53,560 --> 00:31:55,920
Speaker 1: so they would still form together. But then if it's

609
00:31:55,920 --> 00:31:59,720
Speaker 1: the same strength as electromagnetism, then you know, gravity and

610
00:31:59,720 --> 00:32:02,080
Speaker 1: elect a magnetism would be at a tug of war

611
00:32:02,280 --> 00:32:05,080
Speaker 1: very early on, and you get very weird structures, So

612
00:32:05,120 --> 00:32:07,800
Speaker 1: the universe would look totally different. You might get like

613
00:32:07,920 --> 00:32:11,200
Speaker 1: black holes forming very very early on because gravity would

614
00:32:11,200 --> 00:32:13,600
Speaker 1: be so powerful. Well, I feel like these physics scenarios

615
00:32:13,600 --> 00:32:18,520
Speaker 1: never end well for us, Like it's always some crazy

616
00:32:18,600 --> 00:32:21,000
Speaker 1: universe that comes out of it. It wouldn't end well

617
00:32:21,040 --> 00:32:23,960
Speaker 1: for us. It would form some other, very different universe.

618
00:32:24,280 --> 00:32:27,360
Speaker 1: It's hard to imagine what like stable structures would form,

619
00:32:27,800 --> 00:32:29,760
Speaker 1: what it would look like. It might take trillions of

620
00:32:29,800 --> 00:32:32,880
Speaker 1: years to develop complexity or only last for millions of years,

621
00:32:33,080 --> 00:32:35,680
Speaker 1: we don't know, And it might evolve very very different

622
00:32:35,680 --> 00:32:38,720
Speaker 1: forms of life that we can't even imagine, forms of

623
00:32:38,760 --> 00:32:41,360
Speaker 1: life which you know would have podcasts and speculate about

624
00:32:41,400 --> 00:32:43,840
Speaker 1: what the universe would be like if gravity was much weaker.

625
00:32:44,960 --> 00:32:48,719
Speaker 1: I like our podcast better there, but I think I

626
00:32:48,760 --> 00:32:50,520
Speaker 1: think maybe the main question here is like would you

627
00:32:50,560 --> 00:32:52,920
Speaker 1: even see structure in this universe or would it all

628
00:32:53,040 --> 00:32:56,080
Speaker 1: just immediately or very early on, just become all black

629
00:32:56,120 --> 00:32:59,600
Speaker 1: holes Because if gravity is stronger than write things things,

630
00:32:59,640 --> 00:33:02,640
Speaker 1: blacks are easier to make, black holes are easier to make.

631
00:33:02,960 --> 00:33:04,560
Speaker 1: Although to make a black hole you need a lot

632
00:33:04,560 --> 00:33:07,080
Speaker 1: of mass. And so one question is like, are you

633
00:33:07,120 --> 00:33:08,920
Speaker 1: gonna get a lot of small clumps or is gravity

634
00:33:08,920 --> 00:33:11,280
Speaker 1: gonna gather things together into a big clump. Because in

635
00:33:11,280 --> 00:33:14,040
Speaker 1: the early universe, you know, things are very spread out,

636
00:33:14,160 --> 00:33:17,560
Speaker 1: very smooth, and you have these micro fluctuations, these slight

637
00:33:17,680 --> 00:33:21,320
Speaker 1: over densities that let you form structure. Now in this scenario,

638
00:33:21,440 --> 00:33:24,600
Speaker 1: gravity is much much more powerful, so those over densities

639
00:33:24,600 --> 00:33:27,600
Speaker 1: form structure much more quickly. But it's not clear to

640
00:33:27,640 --> 00:33:29,960
Speaker 1: me whether you get a lot of little black holes

641
00:33:30,040 --> 00:33:32,160
Speaker 1: or a bunch of really big black holes, or if

642
00:33:32,200 --> 00:33:35,800
Speaker 1: you might just get things like neutron stars. Right, well,

643
00:33:35,920 --> 00:33:38,880
Speaker 1: but if Grouty was thirty seven times stronger, like those

644
00:33:38,920 --> 00:33:42,560
Speaker 1: neutron stars will probably become black holes much more quickly.

645
00:33:42,680 --> 00:33:45,640
Speaker 1: That's right. Neutron stars in our universe wouldn't survive in

646
00:33:45,680 --> 00:33:48,800
Speaker 1: that universe. But you might get like smaller objects which

647
00:33:48,920 --> 00:33:51,440
Speaker 1: much less gravity there are still stable somehow, you know,

648
00:33:51,560 --> 00:33:54,400
Speaker 1: the strong force could resist the force of gravity. In

649
00:33:54,520 --> 00:33:57,719
Speaker 1: smaller scales, you might get like neutron stars the size

650
00:33:57,840 --> 00:34:00,920
Speaker 1: of your hand instead of ten kilometers wide, for example.

651
00:34:01,320 --> 00:34:04,440
Speaker 1: It's really hard to predict because we can't really calculate

652
00:34:04,480 --> 00:34:07,320
Speaker 1: things using the strong force very well. It's too strong,

653
00:34:07,360 --> 00:34:09,880
Speaker 1: it's too powerful, it's too chaotic, and so these kind

654
00:34:09,880 --> 00:34:12,000
Speaker 1: of simulations are very hard to do. All right, Well,

655
00:34:12,000 --> 00:34:13,839
Speaker 1: then the other part of the question is, like, what

656
00:34:13,880 --> 00:34:16,920
Speaker 1: if gravity suddenly became stronger? Now, Like what if on

657
00:34:17,080 --> 00:34:19,160
Speaker 1: Gut went to the control room of the universe and

658
00:34:19,160 --> 00:34:21,640
Speaker 1: flipped the switch and suddenly we are sitting here, but

659
00:34:21,640 --> 00:34:25,279
Speaker 1: then suddenly gravity is much stronger. On God, please do

660
00:34:25,360 --> 00:34:28,800
Speaker 1: not do that. You would be like the double Fanos

661
00:34:28,920 --> 00:34:31,880
Speaker 1: because everybody you know would die instantly if that happened.

662
00:34:32,000 --> 00:34:35,960
Speaker 1: Oh my goodness, really straight to death. Well, imagine you're

663
00:34:36,000 --> 00:34:38,840
Speaker 1: standing on Earth and all of a sudden gravity becomes

664
00:34:38,880 --> 00:34:42,360
Speaker 1: ten to the thirty seven times more powerful, right, It

665
00:34:42,360 --> 00:34:45,759
Speaker 1: would pulverize you. The tidal forces from Earth would tear

666
00:34:45,840 --> 00:34:48,480
Speaker 1: you apart, you would get squished to the surface. You

667
00:34:48,480 --> 00:34:51,239
Speaker 1: would just not survive. So you're saying Fantasy should have

668
00:34:51,280 --> 00:34:54,440
Speaker 1: been a physicist, because otherwise he would have known what

669
00:34:54,480 --> 00:34:58,080
Speaker 1: to do to do to be a little more fitting exactly,

670
00:34:58,440 --> 00:35:00,880
Speaker 1: and not only would you not vibe, but most of

671
00:35:00,880 --> 00:35:03,680
Speaker 1: the structures we know in the universe would collapse very

672
00:35:03,800 --> 00:35:06,160
Speaker 1: very quickly, because you know, what we have today is

673
00:35:06,200 --> 00:35:09,760
Speaker 1: a balance between gravity and the other forces. The reason

674
00:35:09,840 --> 00:35:12,360
Speaker 1: the Earth doesn't collapse a new black hole is because

675
00:35:12,360 --> 00:35:15,920
Speaker 1: it's internal tensile strength of the materials from the electromagnetic

676
00:35:15,920 --> 00:35:18,879
Speaker 1: bonds are strong enough to prevent that. And the reason

677
00:35:18,960 --> 00:35:21,720
Speaker 1: the Sun hasn't collapsed into a black hole is because

678
00:35:21,760 --> 00:35:25,160
Speaker 1: it's powered by fusion, which is preventing its collapse. Now

679
00:35:25,200 --> 00:35:28,799
Speaker 1: suddenly you're changing half of that equation. Gravity is much

680
00:35:28,880 --> 00:35:31,880
Speaker 1: much stronger. Everything is going to collapse very very quickly.

681
00:35:31,960 --> 00:35:34,920
Speaker 1: So the hearts of stars, for example, will instantly become

682
00:35:35,080 --> 00:35:39,520
Speaker 1: super duper hot because the gravitational pressure. Basically every Sun

683
00:35:39,640 --> 00:35:43,960
Speaker 1: goes supernova instantly. Well, the whole universe just goes up

684
00:35:43,960 --> 00:35:47,719
Speaker 1: in a big explosion kind of and emplosion at the

685
00:35:47,760 --> 00:35:49,759
Speaker 1: same time, like with the Earth, the Earth suddenly become

686
00:35:49,800 --> 00:35:52,040
Speaker 1: a black hole. Yeah, the Earth becomes a black hole.

687
00:35:52,320 --> 00:35:54,840
Speaker 1: The Sun goes supernova and leaves behind a black hole,

688
00:35:55,320 --> 00:35:58,240
Speaker 1: and then you know, the eventual future of our universe

689
00:35:58,360 --> 00:36:01,640
Speaker 1: we imagine is things driping further apart. But getting pulled

690
00:36:01,680 --> 00:36:05,480
Speaker 1: together into black holes. And so basically this just speeds

691
00:36:05,480 --> 00:36:07,799
Speaker 1: that up and turns everything into a black hole much

692
00:36:07,880 --> 00:36:10,680
Speaker 1: much sooner than it otherwise would. Right, But then the

693
00:36:10,760 --> 00:36:15,120
Speaker 1: universe is still expanding, So the gravity bring everything together

694
00:36:15,320 --> 00:36:17,839
Speaker 1: or would the universe continue to expand. The universe would

695
00:36:17,840 --> 00:36:20,360
Speaker 1: continue to expand we think that dark energy is not

696
00:36:20,440 --> 00:36:22,480
Speaker 1: a function of the strength of gravity. But you know,

697
00:36:22,520 --> 00:36:26,479
Speaker 1: there's a balance between dark energy and gravity. Dark energy

698
00:36:26,520 --> 00:36:29,240
Speaker 1: is pulling the universe apart, and gravity is pulling stuff together.

699
00:36:29,719 --> 00:36:32,160
Speaker 1: And currently that balance is at the level of like

700
00:36:32,239 --> 00:36:35,520
Speaker 1: galaxy clusters. We think that gravity wins at the level

701
00:36:35,560 --> 00:36:38,520
Speaker 1: of galaxy clusters. It holds that stuff together and prevents

702
00:36:38,520 --> 00:36:41,040
Speaker 1: it from getting pulled apart by dark energy and anything

703
00:36:41,120 --> 00:36:44,080
Speaker 1: further away, dark energy is winning. Now, if you make

704
00:36:44,200 --> 00:36:47,160
Speaker 1: gravity much much stronger, then dark energy is still gonna

705
00:36:47,160 --> 00:36:50,279
Speaker 1: win at some distances, but gravity is gonna win at

706
00:36:50,360 --> 00:36:52,560
Speaker 1: much bigger things than it did before. So it's going

707
00:36:52,600 --> 00:36:56,080
Speaker 1: to pull together superclusters and clusters of superclusters, and so

708
00:36:56,120 --> 00:36:59,399
Speaker 1: you get these really big monster black holes that would

709
00:36:59,440 --> 00:37:01,719
Speaker 1: contain like, you know, maybe all the stuff in our

710
00:37:01,719 --> 00:37:05,359
Speaker 1: current observable universe. Yeah, I get called them mega black hole,

711
00:37:05,400 --> 00:37:07,840
Speaker 1: which is a cool word. It is a super cool word.

712
00:37:08,000 --> 00:37:11,160
Speaker 1: It's a mega cool word. It's make a cool world.

713
00:37:11,200 --> 00:37:13,960
Speaker 1: There you go from a mega physicist. Alright, well, I

714
00:37:13,960 --> 00:37:17,640
Speaker 1: think that answers the question. Things would be really different, right.

715
00:37:17,760 --> 00:37:20,480
Speaker 1: The universe would have still formed, right, You would still

716
00:37:20,480 --> 00:37:23,920
Speaker 1: get the Big Bang because that expansion is not depending

717
00:37:23,920 --> 00:37:27,239
Speaker 1: on gravity like you said. But um, I guess the

718
00:37:27,360 --> 00:37:30,000
Speaker 1: universe would have just a lot more black holes exactly.

719
00:37:30,040 --> 00:37:32,399
Speaker 1: If gravity was much more powerful early on, you get

720
00:37:32,480 --> 00:37:35,800
Speaker 1: very different structures and early black hole formation. If gravity

721
00:37:35,920 --> 00:37:38,759
Speaker 1: suddenly turned on to be very powerful today, you would

722
00:37:38,800 --> 00:37:41,560
Speaker 1: get in in supernova and then a lot of black holes.

723
00:37:41,640 --> 00:37:43,879
Speaker 1: So I got pleased. Don't press that button, at least

724
00:37:43,920 --> 00:37:47,640
Speaker 1: not yet. You know exactly. I know it's tempting. It's

725
00:37:47,640 --> 00:37:49,560
Speaker 1: the big red button. You want to press it. The

726
00:37:49,600 --> 00:37:53,920
Speaker 1: please take a step back, take a step back. Alright, Well,

727
00:37:53,960 --> 00:37:56,080
Speaker 1: we have one more question here, and it's about things

728
00:37:56,280 --> 00:38:00,040
Speaker 1: disappearing from space, from the universe. So let's get into that.

729
00:38:00,200 --> 00:38:15,640
Speaker 1: But first let's take another quick break. We are answering

730
00:38:15,719 --> 00:38:18,200
Speaker 1: questions from listeners, and our last question here is from

731
00:38:18,320 --> 00:38:22,520
Speaker 1: Keith from Cleveland, who is wondering if things are going

732
00:38:22,560 --> 00:38:25,080
Speaker 1: to disappear in the universe at some point. Hi, Daniel

733
00:38:25,080 --> 00:38:27,520
Speaker 1: and Jorge. This is Keith from Cleveland. I love the

734
00:38:27,520 --> 00:38:30,160
Speaker 1: podcast and I'm amazed at how much time you spend

735
00:38:30,200 --> 00:38:33,359
Speaker 1: answering random listener questions. I don't know how Daniel has

736
00:38:33,360 --> 00:38:35,359
Speaker 1: time left to be a working physicist and have an

737
00:38:35,360 --> 00:38:38,600
Speaker 1: actual life outside of podcasting and question answering, But I'm

738
00:38:38,640 --> 00:38:41,320
Speaker 1: going to add to that burden anyways by asking questions.

739
00:38:41,960 --> 00:38:45,400
Speaker 1: And that is, have we been observing deep enough into

740
00:38:45,400 --> 00:38:48,080
Speaker 1: space for a long enough time that something we used

741
00:38:48,120 --> 00:38:50,560
Speaker 1: to be able to see has receded to a point

742
00:38:50,560 --> 00:38:52,400
Speaker 1: where it can no longer be seen due to the

743
00:38:52,440 --> 00:38:55,799
Speaker 1: expansion of the universe. For example, is our galaxy that

744
00:38:55,840 --> 00:39:00,439
Speaker 1: we detected, say by, that has since disappeared for from

745
00:39:00,440 --> 00:39:03,520
Speaker 1: our view because it is no longer within our hubble volume,

746
00:39:03,840 --> 00:39:06,640
Speaker 1: and thus that galaxy's photons will now never reach us.

747
00:39:07,120 --> 00:39:09,160
Speaker 1: Do we know of such an object? And if not,

748
00:39:09,320 --> 00:39:11,600
Speaker 1: how long do we need to wait between observing a

749
00:39:11,680 --> 00:39:15,000
Speaker 1: very distant object and it disappearing forever? Thanks so much

750
00:39:15,000 --> 00:39:16,920
Speaker 1: and keep up the great work all right. Thank you.

751
00:39:17,000 --> 00:39:19,600
Speaker 1: Keith from Cleveland. That's a little bit hard to say,

752
00:39:19,680 --> 00:39:23,400
Speaker 1: Keith from Cleveland. I wonder if he became a physicists

753
00:39:24,480 --> 00:39:28,759
Speaker 1: really extra hard to pronounce. This is his Keith from Cleveland. Yeah,

754
00:39:28,760 --> 00:39:31,279
Speaker 1: but he asked a really cool question about the nature

755
00:39:31,280 --> 00:39:33,239
Speaker 1: of the universe and what we can see in it.

756
00:39:33,360 --> 00:39:36,280
Speaker 1: He also has a great question about the nature of Daniel. Daniel,

757
00:39:36,480 --> 00:39:39,080
Speaker 1: how do you find at the time to do all

758
00:39:39,120 --> 00:39:41,680
Speaker 1: everything you do? Time dilation? You know, you move fast

759
00:39:41,800 --> 00:39:45,319
Speaker 1: enough and clocks go slow? Interesting? Interesting? Or do you

760
00:39:45,320 --> 00:39:47,520
Speaker 1: get close to a black hole? Right? Is that great?

761
00:39:47,560 --> 00:39:50,440
Speaker 1: Do you have one in your house? But then I

762
00:39:50,440 --> 00:39:52,279
Speaker 1: would slow down and the rest of the universe would

763
00:39:52,280 --> 00:39:54,479
Speaker 1: speed up, So then you need to put the rest

764
00:39:54,480 --> 00:39:56,919
Speaker 1: of the universe near a black hole while you get

765
00:39:56,920 --> 00:40:00,520
Speaker 1: your work done. So I see, maybe have a white

766
00:40:00,520 --> 00:40:03,040
Speaker 1: hole in your house. You are Oh, you aren't called

767
00:40:03,040 --> 00:40:10,200
Speaker 1: whitesn you figured it out. I am Carlott Holmes Elementary.

768
00:40:10,320 --> 00:40:12,080
Speaker 1: But not to answer you keeps question. I am still

769
00:40:12,120 --> 00:40:14,560
Speaker 1: a working physicist. I'm doing data analysis from the Large

770
00:40:14,560 --> 00:40:18,120
Speaker 1: Agon Collider. I got undergrads and grad students and post

771
00:40:18,160 --> 00:40:20,120
Speaker 1: docs working with me, and we're just having a lot

772
00:40:20,160 --> 00:40:23,480
Speaker 1: of fun answering questions about the universe. Yeah. Yeah, you're

773
00:40:23,520 --> 00:40:26,080
Speaker 1: still working as a physicist. You're just not pronouncing it

774
00:40:26,680 --> 00:40:28,520
Speaker 1: as well as he could not part of the job.

775
00:40:28,560 --> 00:40:31,560
Speaker 1: As far as I understand, you don't listen on your

776
00:40:31,560 --> 00:40:34,759
Speaker 1: resume can pronounce my job title, Joe is. I can't

777
00:40:34,760 --> 00:40:36,960
Speaker 1: even really spell it. There's so many scenes and asses

778
00:40:37,000 --> 00:40:39,480
Speaker 1: in it. I get it wrong every single time. Do

779
00:40:39,560 --> 00:40:41,640
Speaker 1: you spell it like a psychic baby? Yeah, it's like

780
00:40:41,680 --> 00:40:43,560
Speaker 1: trying to spell the word license. It's like where does

781
00:40:43,560 --> 00:40:45,600
Speaker 1: that see you go? And a good thing. I don't

782
00:40:45,640 --> 00:40:48,000
Speaker 1: need a physics license because I couldn't spell either world

783
00:40:48,040 --> 00:40:50,520
Speaker 1: my goodness or that you're a real doctor too, you'd

784
00:40:50,520 --> 00:40:54,520
Speaker 1: be a physicians physicist licensee. Al Right, Well, this question

785
00:40:54,640 --> 00:40:57,080
Speaker 1: was it sort of related to what we're talking about before,

786
00:40:57,280 --> 00:41:00,239
Speaker 1: the idea that there are parts of space that we

787
00:41:00,280 --> 00:41:03,200
Speaker 1: can see now and there are parts of space that

788
00:41:03,280 --> 00:41:05,880
Speaker 1: we maybe we will never see because the universe is

789
00:41:05,920 --> 00:41:09,880
Speaker 1: expanding faster and faster, And I think he's is asking like,

790
00:41:10,000 --> 00:41:12,400
Speaker 1: have we gotten to that point yet, Like have we

791
00:41:12,480 --> 00:41:14,600
Speaker 1: noticed that there are things we can't see anymore? Yeah,

792
00:41:14,640 --> 00:41:17,000
Speaker 1: it's a really interesting question. You right, he's asking about

793
00:41:17,000 --> 00:41:20,640
Speaker 1: whether things are falling off the edge of the observable universe.

794
00:41:21,040 --> 00:41:23,520
Speaker 1: And first of all, he's right that things will fall

795
00:41:23,560 --> 00:41:25,920
Speaker 1: off the edge of the observable universe. And that's because

796
00:41:25,920 --> 00:41:29,000
Speaker 1: space is expanding faster than light, right, so space is

797
00:41:29,040 --> 00:41:32,239
Speaker 1: stretching out right, Well, the observable universe expands that a

798
00:41:32,360 --> 00:41:36,239
Speaker 1: light year per year. Space itself is expanding faster than that,

799
00:41:36,600 --> 00:41:39,120
Speaker 1: and so there are things that are moving into parts

800
00:41:39,120 --> 00:41:41,319
Speaker 1: of the universe that are expanding faster than the speed

801
00:41:41,360 --> 00:41:44,520
Speaker 1: of light, where their photons will no longer ever reach us.

802
00:41:44,880 --> 00:41:47,520
Speaker 1: So there are things falling off the edge of the

803
00:41:47,520 --> 00:41:51,040
Speaker 1: observable universe. It's like, you know, somebody stretching out the

804
00:41:51,040 --> 00:41:53,319
Speaker 1: fabric faster than we're looking at it, and so we're

805
00:41:53,360 --> 00:41:56,759
Speaker 1: seeing a smaller and smaller fraction of the stuff in

806
00:41:56,800 --> 00:42:00,880
Speaker 1: the universe. Well, but it's not sort of like alling off.

807
00:42:01,000 --> 00:42:04,279
Speaker 1: It's more like the observable universe is growing, but it's

808
00:42:04,480 --> 00:42:06,880
Speaker 1: just not there are things that are outpacing it, or

809
00:42:07,280 --> 00:42:11,200
Speaker 1: they're running away from us faster than that bubble is expanding. Yeah,

810
00:42:11,239 --> 00:42:12,880
Speaker 1: they're not falling off from the edge into like the

811
00:42:12,920 --> 00:42:15,520
Speaker 1: mouth of dragons or something like that. We think there

812
00:42:15,520 --> 00:42:18,160
Speaker 1: probably is still space out there for this stuff to

813
00:42:18,200 --> 00:42:20,759
Speaker 1: be in, but it's sort of disappearing from our view.

814
00:42:20,920 --> 00:42:23,880
Speaker 1: So you're right, the expansion is outpacing the speed of line, right,

815
00:42:23,880 --> 00:42:26,600
Speaker 1: And it's not like it's they're falling out of our view.

816
00:42:26,680 --> 00:42:29,400
Speaker 1: It's just that they never were in our view and

817
00:42:29,440 --> 00:42:32,239
Speaker 1: they never will. Well, there's things in different categories. There's

818
00:42:32,239 --> 00:42:35,600
Speaker 1: stuff that was observable and in the future will not

819
00:42:35,680 --> 00:42:38,239
Speaker 1: be observable, things that sort of move out of the

820
00:42:38,280 --> 00:42:42,200
Speaker 1: observable universe. There are things which started out not observable,

821
00:42:42,360 --> 00:42:44,880
Speaker 1: and we're in parts of space that we're expanding faster

822
00:42:44,960 --> 00:42:48,239
Speaker 1: than the speed of light and then briefly are observable

823
00:42:48,239 --> 00:42:50,319
Speaker 1: and then fall out. And then there are things that

824
00:42:50,400 --> 00:42:53,359
Speaker 1: never will be observable, things that, no matter how much

825
00:42:53,400 --> 00:42:56,520
Speaker 1: time passes, photons from them will never reach us. Oh,

826
00:42:57,160 --> 00:42:58,440
Speaker 1: you just blew my mind a little bit. That was

827
00:42:58,480 --> 00:43:02,560
Speaker 1: like four categories of things. Let's let's maybe take one

828
00:43:02,560 --> 00:43:05,800
Speaker 1: out a time. So there are our silver universe is expanding,

829
00:43:06,280 --> 00:43:08,200
Speaker 1: there's stats of the stuff we can see for sure.

830
00:43:08,719 --> 00:43:11,280
Speaker 1: We talked about before earlier in this episode. How there's

831
00:43:11,360 --> 00:43:14,640
Speaker 1: things like out there beyond sixty five billion light years

832
00:43:14,640 --> 00:43:18,120
Speaker 1: away that will never see because space is expanding and

833
00:43:18,120 --> 00:43:20,759
Speaker 1: so it will never like our our silver universe will

834
00:43:20,800 --> 00:43:23,080
Speaker 1: never catch up to that, right, that's right. It's sixty

835
00:43:23,200 --> 00:43:26,000
Speaker 1: three billion light years in radius. Things further than that,

836
00:43:26,040 --> 00:43:29,480
Speaker 1: the recession velocity is greater than the speed of light

837
00:43:29,520 --> 00:43:32,520
Speaker 1: and always will be, and so those photons will never

838
00:43:32,520 --> 00:43:34,800
Speaker 1: reach us because they'll always be in parts of space

839
00:43:35,080 --> 00:43:38,120
Speaker 1: where the recession velocity is greater than the speed of light.

840
00:43:38,239 --> 00:43:41,240
Speaker 1: So there are distance to us will always be getting larger,

841
00:43:41,320 --> 00:43:45,000
Speaker 1: even though they're technically moving towards us through their space. Right.

842
00:43:45,040 --> 00:43:46,719
Speaker 1: And when you say always, you mean as long as

843
00:43:46,719 --> 00:43:49,480
Speaker 1: the universe keeps expanding, right, that's right. And this is

844
00:43:49,520 --> 00:43:53,279
Speaker 1: assuming the current cosmological model and that the expansion continues

845
00:43:53,320 --> 00:43:55,719
Speaker 1: in the way that it has, which is fascinating, you know,

846
00:43:55,760 --> 00:43:58,879
Speaker 1: because there was very early expansion inflation the first few

847
00:43:58,880 --> 00:44:01,840
Speaker 1: moments of the universe, and then there's late time expansion,

848
00:44:01,920 --> 00:44:04,960
Speaker 1: this time around eight billion years after the universe started,

849
00:44:05,160 --> 00:44:08,440
Speaker 1: when they started accelerating again, the sort of two modes

850
00:44:08,480 --> 00:44:10,600
Speaker 1: of expansion. And what we're doing now is we're assuming

851
00:44:11,040 --> 00:44:13,920
Speaker 1: that that recent expansion in the last few billion years

852
00:44:13,960 --> 00:44:16,480
Speaker 1: just sort of continues forever. But we don't know, right,

853
00:44:16,520 --> 00:44:18,360
Speaker 1: it could be different. It could be that the future

854
00:44:18,440 --> 00:44:20,799
Speaker 1: is is something else, right, But as far as we know,

855
00:44:20,840 --> 00:44:23,239
Speaker 1: it seems like there's stuff we can see stuff we

856
00:44:23,280 --> 00:44:26,080
Speaker 1: will never see. And then very interestingly, he said, there

857
00:44:26,120 --> 00:44:28,560
Speaker 1: are two kinds of things that we can see now

858
00:44:28,680 --> 00:44:31,480
Speaker 1: but that we won't see in the future. So what

859
00:44:31,520 --> 00:44:34,359
Speaker 1: are those two things? So one is stuff that has

860
00:44:34,400 --> 00:44:38,000
Speaker 1: been in our observable universe, but eventually we'll fall out

861
00:44:38,080 --> 00:44:41,759
Speaker 1: of our observable universe because it's moving within space. Well,

862
00:44:41,800 --> 00:44:44,759
Speaker 1: because space is expanding. You know, things for example, that

863
00:44:44,840 --> 00:44:48,520
Speaker 1: we're between us and forty two million light years away,

864
00:44:49,000 --> 00:44:51,680
Speaker 1: very very early on in the universe, like around the

865
00:44:51,719 --> 00:44:54,799
Speaker 1: CMB time. That's stuff we can see right now. Oh,

866
00:44:54,880 --> 00:44:56,600
Speaker 1: I see you're saying. I would have thought like once

867
00:44:56,640 --> 00:44:59,480
Speaker 1: we see something like we can see it forever. No,

868
00:45:00,000 --> 00:45:01,880
Speaker 1: So if you go back to the very beginning, right

869
00:45:02,000 --> 00:45:04,960
Speaker 1: T equal zero, technically we could see nothing, right, so

870
00:45:04,960 --> 00:45:07,200
Speaker 1: we couldn't see any part of the observable universe was

871
00:45:07,239 --> 00:45:10,520
Speaker 1: a sphere of zero volume. Then as time goes on,

872
00:45:10,840 --> 00:45:12,879
Speaker 1: that expands and we start to be able to see

873
00:45:12,960 --> 00:45:16,080
Speaker 1: things in the universe, right, and so things enter the

874
00:45:16,160 --> 00:45:19,320
Speaker 1: observable universe. Not everything is going to enter that however,

875
00:45:19,760 --> 00:45:22,279
Speaker 1: right there's still things so far away that they will

876
00:45:22,320 --> 00:45:25,400
Speaker 1: never enter the observable universe because at the same time,

877
00:45:25,480 --> 00:45:28,160
Speaker 1: space is expanding, so you know, you have this race

878
00:45:28,200 --> 00:45:30,960
Speaker 1: between the observable universe, which is growing at one light

879
00:45:31,040 --> 00:45:34,239
Speaker 1: year per year, and space expanding, which is tugging things

880
00:45:34,239 --> 00:45:36,520
Speaker 1: away from us. So in the very beginning, nothing's in

881
00:45:36,560 --> 00:45:39,880
Speaker 1: the observable universe. Then as time goes on, some things

882
00:45:40,000 --> 00:45:42,440
Speaker 1: come into the observable universe and we can see them,

883
00:45:42,480 --> 00:45:44,839
Speaker 1: though not everything. There's some things that will never enter

884
00:45:44,920 --> 00:45:47,360
Speaker 1: the observable universe. But the stuff that falls into the

885
00:45:47,360 --> 00:45:50,160
Speaker 1: observable universe that comes into the observa universe, so we

886
00:45:50,200 --> 00:45:54,800
Speaker 1: can see it. Eventually, also it will leave because space

887
00:45:54,880 --> 00:45:57,000
Speaker 1: is expanding fast in the speed of light, so that

888
00:45:57,040 --> 00:46:00,160
Speaker 1: will win and eventually everything will get pulled out out

889
00:46:00,160 --> 00:46:03,760
Speaker 1: of our universe. And even though technically the observing universe

890
00:46:03,800 --> 00:46:07,040
Speaker 1: will be large, will essentially be nothing in it anymore. Right, Well,

891
00:46:07,040 --> 00:46:10,080
Speaker 1: I think, maybe just to be clear, like the space

892
00:46:10,239 --> 00:46:13,160
Speaker 1: within the observable universe right now, it's not expanding faster

893
00:46:13,200 --> 00:46:15,839
Speaker 1: than the speed of light, but it's accelerating all the time,

894
00:46:16,000 --> 00:46:18,239
Speaker 1: and space is stretching faster and faster. So I think

895
00:46:18,280 --> 00:46:20,719
Speaker 1: what you're saying is that eventually the space within the

896
00:46:20,719 --> 00:46:24,200
Speaker 1: observable universe. That stuff is gradually going to be going

897
00:46:24,239 --> 00:46:26,080
Speaker 1: faster than the speed of light, and then at some

898
00:46:26,120 --> 00:46:28,760
Speaker 1: point it's gonna you know, catch up to the observable

899
00:46:28,840 --> 00:46:31,319
Speaker 1: universe and even pass it, in which case we won't

900
00:46:31,320 --> 00:46:33,080
Speaker 1: be able to see it. Ye, So the bubble that

901
00:46:33,120 --> 00:46:36,560
Speaker 1: we can see keeps growing, but stuff gets accelerated away

902
00:46:36,600 --> 00:46:39,920
Speaker 1: from us faster than that bubble keeps growing, and so

903
00:46:39,960 --> 00:46:42,440
Speaker 1: eventually everything sort of falls out of our I like

904
00:46:42,480 --> 00:46:44,080
Speaker 1: to say falls out, but you're right, it's not like

905
00:46:44,280 --> 00:46:48,240
Speaker 1: tripping over the edge. It's outpacing the growth of that bubble.

906
00:46:49,040 --> 00:46:51,279
Speaker 1: I feel like it's it's a very exciting race. It's like,

907
00:46:51,640 --> 00:46:54,279
Speaker 1: you know, the observable universe was winning, but then the

908
00:46:54,280 --> 00:46:56,640
Speaker 1: expansion was winning, but then that one was losing. And

909
00:46:57,960 --> 00:47:00,479
Speaker 1: there's some people caught in some stars in the middle

910
00:47:00,560 --> 00:47:02,920
Speaker 1: that are unfortunately going to be winning but then losing.

911
00:47:03,000 --> 00:47:05,640
Speaker 1: And it's a pretty pretty dramatic story. It's a pretty

912
00:47:05,719 --> 00:47:08,400
Speaker 1: dramatic story. And you think about an individual thing, it

913
00:47:08,600 --> 00:47:11,959
Speaker 1: starts out invisible, right, and essentially you can think about

914
00:47:12,000 --> 00:47:15,239
Speaker 1: that is like having infinite red shift. Red shift in

915
00:47:15,360 --> 00:47:18,799
Speaker 1: infinity is totally invisible. So things that are going to

916
00:47:18,840 --> 00:47:21,280
Speaker 1: be in our observa universe, start out an infinite red shift,

917
00:47:21,440 --> 00:47:24,120
Speaker 1: and then they come into our observa universe, and at

918
00:47:24,160 --> 00:47:27,640
Speaker 1: some point in time they reach like their minimum red shift,

919
00:47:28,239 --> 00:47:30,480
Speaker 1: and then they turn around and they start to grow

920
00:47:30,520 --> 00:47:34,319
Speaker 1: their redshift again as the universe acceleration takes over and

921
00:47:34,320 --> 00:47:36,840
Speaker 1: they go back to infinite redshift. So everything sort of

922
00:47:36,840 --> 00:47:39,879
Speaker 1: starts in infinity, comes to a minimum redshift, and then

923
00:47:39,880 --> 00:47:42,520
Speaker 1: goes to infinite red shift. Some things are always an

924
00:47:42,560 --> 00:47:45,360
Speaker 1: infinite redshift and will never see them, those things past

925
00:47:45,440 --> 00:47:49,239
Speaker 1: our eventual particle horizon. Well, I think keith question though,

926
00:47:49,440 --> 00:47:52,640
Speaker 1: is like has that started to happen? Right? Like, has

927
00:47:52,680 --> 00:47:57,040
Speaker 1: stuff within our absorbable universe started to accelerate faster than

928
00:47:57,040 --> 00:47:59,600
Speaker 1: the speed of light? Because it's possible that it hasn't

929
00:47:59,640 --> 00:48:02,279
Speaker 1: started right. Well, there's always something right at the edge.

930
00:48:02,320 --> 00:48:05,120
Speaker 1: There's something that is falling off. Right, Since the universe

931
00:48:05,160 --> 00:48:07,960
Speaker 1: started accelerating about eight billion years ago, things that are

932
00:48:08,040 --> 00:48:10,239
Speaker 1: right there at the edge started to lose that race.

933
00:48:10,680 --> 00:48:13,400
Speaker 1: So there's always something that's passing that threshold, but but

934
00:48:13,480 --> 00:48:16,000
Speaker 1: not necessarily right. It could have been right because the

935
00:48:16,040 --> 00:48:18,879
Speaker 1: universe's expressed out and it could be like like right, now,

936
00:48:18,880 --> 00:48:21,960
Speaker 1: it could be that the observerable universe it's expanding at

937
00:48:22,000 --> 00:48:23,840
Speaker 1: the speed of light. But it could be that maybe

938
00:48:23,920 --> 00:48:26,799
Speaker 1: the expansion up to the point hasn't reached that right. Well,

939
00:48:26,840 --> 00:48:30,319
Speaker 1: remember that the recession velocity is linear, that's hubbled laws.

940
00:48:30,360 --> 00:48:32,600
Speaker 1: So things that are close to us are not moving

941
00:48:32,640 --> 00:48:34,440
Speaker 1: away from us that fast, And as you go further

942
00:48:34,480 --> 00:48:36,680
Speaker 1: and further away, things are moving away from us faster

943
00:48:36,760 --> 00:48:39,399
Speaker 1: and faster, and that's linear. So as you go far

944
00:48:39,520 --> 00:48:41,719
Speaker 1: enough away, there's always something that's moving away from us

945
00:48:41,760 --> 00:48:44,640
Speaker 1: faster than the speed of light. Yes, but that thing

946
00:48:44,680 --> 00:48:47,279
Speaker 1: could be outside of our observable universe right now, or

947
00:48:47,320 --> 00:48:49,480
Speaker 1: it could be inside of our observable universe. Right If

948
00:48:49,480 --> 00:48:51,719
Speaker 1: it's outside the observable universe, then right now we can

949
00:48:51,760 --> 00:48:54,960
Speaker 1: see everything. But eventually it's going to catch up. So

950
00:48:55,040 --> 00:48:58,800
Speaker 1: things are moving away from as faster as they're more distant. Currently,

951
00:48:58,800 --> 00:49:00,520
Speaker 1: in order to be moving away from us faster than

952
00:49:00,560 --> 00:49:02,400
Speaker 1: the speed of light, you only need to be about

953
00:49:02,440 --> 00:49:05,880
Speaker 1: fifteen billion light years away, So most of the observable

954
00:49:05,960 --> 00:49:08,560
Speaker 1: universe is moving away from us faster than the speed

955
00:49:08,560 --> 00:49:12,879
Speaker 1: of light. Oh. Interesting, So there are things that are

956
00:49:13,040 --> 00:49:16,440
Speaker 1: falling out of our view, but in the past, there wasn't,

957
00:49:16,960 --> 00:49:19,040
Speaker 1: but now there is. I think there are always things

958
00:49:19,040 --> 00:49:21,240
Speaker 1: that are falling out of our view if the universe

959
00:49:21,320 --> 00:49:24,240
Speaker 1: is expanding and accelerating at the same rate. But wasn't

960
00:49:24,239 --> 00:49:27,600
Speaker 1: the universe expanding slower before? Yeah, the expansion has been

961
00:49:27,640 --> 00:49:31,719
Speaker 1: accelerating exactly. So now there are things falling out of

962
00:49:31,760 --> 00:49:34,600
Speaker 1: the edge of our durable universe or getting outpaced by

963
00:49:34,640 --> 00:49:36,480
Speaker 1: the expansion. I think is your phrase, which I think

964
00:49:36,560 --> 00:49:40,520
Speaker 1: is better interesting. Alright, So Keith was right these I

965
00:49:40,560 --> 00:49:42,480
Speaker 1: mean he was asking when that's going to happen, and

966
00:49:42,520 --> 00:49:46,560
Speaker 1: you're saying it's already happened. We're losing the universe. Yeah,

967
00:49:46,600 --> 00:49:50,160
Speaker 1: And Keith was asking whether we've seen something disappear, which

968
00:49:50,200 --> 00:49:53,080
Speaker 1: is a really cool question and similar to your question

969
00:49:53,120 --> 00:49:56,040
Speaker 1: before about like seeing the CMB change. So if you're

970
00:49:56,080 --> 00:49:58,400
Speaker 1: like looking at an object that you know is really

971
00:49:58,480 --> 00:50:01,439
Speaker 1: far away now, right, And remember that when we're talking

972
00:50:01,480 --> 00:50:03,840
Speaker 1: about seeing an object that's really far away, there's a

973
00:50:03,840 --> 00:50:06,800
Speaker 1: subtlety here. If we say something that we're seeing is

974
00:50:06,840 --> 00:50:10,080
Speaker 1: forty six billion light years away, we mean that's where

975
00:50:10,160 --> 00:50:13,520
Speaker 1: it is right now, right, So we're seeing light from

976
00:50:13,520 --> 00:50:16,040
Speaker 1: it that was admitted when that object was closer to us,

977
00:50:16,560 --> 00:50:19,040
Speaker 1: but now where it is is forty six billion light

978
00:50:19,120 --> 00:50:22,200
Speaker 1: years away. That's when we mean when we say the

979
00:50:22,320 --> 00:50:24,440
Speaker 1: edge of the observable universe. Right, we're not seeing that

980
00:50:24,440 --> 00:50:27,360
Speaker 1: stuff today. We're seeing it from when it was actually

981
00:50:27,440 --> 00:50:30,960
Speaker 1: closer from where it was when it sent us a photon. Anyway,

982
00:50:31,160 --> 00:50:32,640
Speaker 1: we are looking at stuff at the edge of the

983
00:50:32,640 --> 00:50:35,239
Speaker 1: observd a universe. And so for example, there's a galaxy

984
00:50:35,320 --> 00:50:38,719
Speaker 1: people have looked at that might be the most distant object.

985
00:50:38,960 --> 00:50:41,680
Speaker 1: You know, the CNB is older and more distant. But

986
00:50:41,760 --> 00:50:44,680
Speaker 1: this is an object near the edge of the observable universe.

987
00:50:44,719 --> 00:50:47,799
Speaker 1: It's called g n Z eleven and it was a

988
00:50:47,840 --> 00:50:51,080
Speaker 1: galaxy formed about four hundred million years after the Big Bang.

989
00:50:51,120 --> 00:50:52,400
Speaker 1: If you look at the pictures of it, it just

990
00:50:52,440 --> 00:50:54,640
Speaker 1: sort of looks like a blob that the James Webb

991
00:50:54,800 --> 00:50:57,800
Speaker 1: Space Telescope. Of course, we'll get very very crisp pictures

992
00:50:57,800 --> 00:50:59,919
Speaker 1: of this object and help us understand like the early

993
00:51:00,160 --> 00:51:03,040
Speaker 1: universe and galaxy formation. So this is a candidate for

994
00:51:03,080 --> 00:51:05,839
Speaker 1: the kind of thing we expect to disappear from our

995
00:51:05,920 --> 00:51:09,480
Speaker 1: universe because it's very close to the edge. Right, interesting,

996
00:51:09,560 --> 00:51:12,000
Speaker 1: you know, but I guess you're saying that it's not

997
00:51:12,000 --> 00:51:14,040
Speaker 1: gonna like blink out at some point where it's not

998
00:51:14,040 --> 00:51:15,759
Speaker 1: going to blink out in the space of ten years.

999
00:51:15,800 --> 00:51:20,880
Speaker 1: It's gonna slowly red shift into sort of blackness, right. Exactly.

1000
00:51:20,920 --> 00:51:23,520
Speaker 1: The reason the James Webb is a good telescope to

1001
00:51:23,520 --> 00:51:26,960
Speaker 1: look at it is because its wavelengths are already really

1002
00:51:27,040 --> 00:51:30,400
Speaker 1: red shifted into the I, R and two infrared wavelengths,

1003
00:51:30,920 --> 00:51:32,719
Speaker 1: and as the time goes on, it's just going to

1004
00:51:32,840 --> 00:51:35,560
Speaker 1: gradually get more and more red shifted until it gets

1005
00:51:35,600 --> 00:51:38,040
Speaker 1: to red shift of infinity. So you're right, it's not

1006
00:51:38,080 --> 00:51:41,160
Speaker 1: going to just disappear one day. It's gonna gradually get

1007
00:51:41,200 --> 00:51:44,239
Speaker 1: redder and redder. It's not going to be very dramatic, unfortunately,

1008
00:51:44,520 --> 00:51:46,239
Speaker 1: and it's gonna take a long time to really even

1009
00:51:46,280 --> 00:51:50,600
Speaker 1: notice any differences. These things take cosmological time periods to change,

1010
00:51:51,000 --> 00:51:54,719
Speaker 1: not days or weeks or years. Kase, just watch what

1011
00:51:54,760 --> 00:51:56,839
Speaker 1: you eat and you might live long enough to see

1012
00:51:56,880 --> 00:52:01,239
Speaker 1: it disappear. But it sort of makes me a little sad.

1013
00:52:01,280 --> 00:52:03,520
Speaker 1: I feel like you're telling me that we've already started to,

1014
00:52:04,120 --> 00:52:06,719
Speaker 1: you know, see less of the universe, like our view

1015
00:52:06,719 --> 00:52:09,840
Speaker 1: of the universe, like as has already started to disappear.

1016
00:52:10,440 --> 00:52:12,600
Speaker 1: Does that mean that, like what we see today is

1017
00:52:12,640 --> 00:52:15,560
Speaker 1: the most we'll see of the universe. Ever, while there

1018
00:52:15,560 --> 00:52:18,279
Speaker 1: are things disappearing, there are also things that we have

1019
00:52:18,480 --> 00:52:21,000
Speaker 1: not yet seen that we will see. Things that have

1020
00:52:21,000 --> 00:52:22,880
Speaker 1: been flying through the universe the whole history of the

1021
00:52:23,000 --> 00:52:25,880
Speaker 1: universe and have not yet arrived. But they will arrive

1022
00:52:26,239 --> 00:52:29,000
Speaker 1: because right now they're flying through space that's not moving

1023
00:52:29,040 --> 00:52:31,120
Speaker 1: away from us faster than the speed of light. They've

1024
00:52:31,640 --> 00:52:34,960
Speaker 1: made it inside the hubble radius, and they will eventually

1025
00:52:34,960 --> 00:52:36,920
Speaker 1: reach us. So, for example, there are things that are

1026
00:52:36,960 --> 00:52:40,520
Speaker 1: sixty three billion light years away the very first flashes

1027
00:52:40,600 --> 00:52:43,640
Speaker 1: they sent in the very early universe. Those will eventually

1028
00:52:43,719 --> 00:52:47,439
Speaker 1: reach us. Nothing else afterwards that they send will ever

1029
00:52:47,520 --> 00:52:50,920
Speaker 1: reach us, right so they'll very briefly dip into our

1030
00:52:50,920 --> 00:52:54,719
Speaker 1: observable universe at the very end of time. So there

1031
00:52:54,719 --> 00:52:56,719
Speaker 1: are some things where the light is still on its

1032
00:52:56,760 --> 00:52:59,120
Speaker 1: way that will reach us. But there are also things

1033
00:52:59,120 --> 00:53:01,520
Speaker 1: that right now there are ready disappearing from the universe.

1034
00:53:02,000 --> 00:53:04,560
Speaker 1: So every photon as it passes through the universe sort

1035
00:53:04,560 --> 00:53:08,080
Speaker 1: of passes through a different universe because space is expanding,

1036
00:53:08,080 --> 00:53:10,840
Speaker 1: and that expansion is changing with time. So photons that

1037
00:53:10,920 --> 00:53:13,160
Speaker 1: left a long time ago have had a chance to

1038
00:53:13,280 --> 00:53:16,640
Speaker 1: make it within the sphere that's no longer expanding faster

1039
00:53:16,680 --> 00:53:19,160
Speaker 1: than the speed of light, so they will eventually get here,

1040
00:53:19,239 --> 00:53:22,600
Speaker 1: although later photons from the same super distant objects won't

1041
00:53:22,680 --> 00:53:24,719
Speaker 1: get here. All right, Well, I think the answer for

1042
00:53:24,840 --> 00:53:28,680
Speaker 1: Keith is that things have started disappearing now, or they

1043
00:53:28,880 --> 00:53:31,759
Speaker 1: they are starting to disappear, but it might be a

1044
00:53:31,760 --> 00:53:36,000
Speaker 1: little bit before we stopped getting new things into our

1045
00:53:36,000 --> 00:53:38,279
Speaker 1: field of view. Like, we haven't peaked yet in terms

1046
00:53:38,320 --> 00:53:40,720
Speaker 1: of our view of the universe, but we will something

1047
00:53:41,200 --> 00:53:43,600
Speaker 1: That's right, the most distant thing we see will be

1048
00:53:43,680 --> 00:53:47,080
Speaker 1: sixty three billion night years away. We haven't yet seen that.

1049
00:53:47,120 --> 00:53:49,520
Speaker 1: We will see it very briefly at the end of time,

1050
00:53:49,600 --> 00:53:52,160
Speaker 1: and we will never see anything more distant than that.

1051
00:53:52,239 --> 00:53:54,320
Speaker 1: At the same time, there are some things which are closer,

1052
00:53:54,320 --> 00:53:58,080
Speaker 1: which spend more time in our abservable universe, but are

1053
00:53:58,120 --> 00:54:02,640
Speaker 1: already being outpaced by the accelerating expansion in the universe. Unfortunately,

1054
00:54:02,680 --> 00:54:04,799
Speaker 1: they don't blink out dramatically, They just sort of read

1055
00:54:04,840 --> 00:54:07,759
Speaker 1: shift away. All right, Well, um, stay tuned. I guess

1056
00:54:07,840 --> 00:54:12,040
Speaker 1: until the end of time we'll find out the answer

1057
00:54:12,080 --> 00:54:14,640
Speaker 1: that hopefully we'll be making this podcast until the end

1058
00:54:14,680 --> 00:54:17,200
Speaker 1: of time. Hopefully you'll learn how to pronounce the word

1059
00:54:17,200 --> 00:54:20,080
Speaker 1: physicists by then. That will take two or three universes,

1060
00:54:20,120 --> 00:54:23,520
Speaker 1: I think, Yeah, maybe in the next universe. You'll flick

1061
00:54:23,640 --> 00:54:26,120
Speaker 1: it out. In the next universe. All right, I'll put

1062
00:54:26,120 --> 00:54:28,640
Speaker 1: it on my two do list for next universe. That's right,

1063
00:54:28,840 --> 00:54:31,920
Speaker 1: it's stay tuned for the sequel. Uh the universe. The

1064
00:54:32,000 --> 00:54:35,759
Speaker 1: dark matter returns correctly pronounced with pants on. Alright, Well,

1065
00:54:35,760 --> 00:54:38,399
Speaker 1: we hope you enjoyed that. Thanks for joining us, See

1066
00:54:38,440 --> 00:54:48,640
Speaker 1: you next time. Thanks for listening, and remember that Daniel

1067
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Speaker 1: and Jorge Explain the Universe is a production of I

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Speaker 1: Heart Radio. For more podcast from my Heart Radio, visit

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Speaker 1: the I Heart Radio app, Apple Podcasts, or wherever you

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Speaker 1: listen to your favorite show. M