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Speaker 1: What is the moment of scientific discovery actually? Like I mean,

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Speaker 1: in the movies, it always seems so crisp. Scientists find

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Speaker 1: something in her data or an experiment suddenly dramatically works.

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Speaker 1: We go from ignorance to knowledge in a moment, from

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Speaker 1: failure to success. That kind of drama works for the

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Speaker 1: movie screen, But how does it happen in real life?

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Speaker 1: Is it a slow and steady march rather than a

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Speaker 1: sudden leap, or are there actually real moments of insight

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Speaker 1: where all of a sudden light penetrates the darkness and

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Speaker 1: the scientists learned something new about the universe that no

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Speaker 1: human has ever known before. Hi, I'm Daniel. I'm a

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Speaker 1: particle physicist and I've been doing particle physics experiments for

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Speaker 1: decades but never discovered a new particle. And Welcome to

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Speaker 1: the podcast. Daniel and Jorge explain the Universe, in which

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Speaker 1: we examine everything about the universe, from its origins to

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Speaker 1: its ends, from its biggest things to its smallest things,

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Speaker 1: from all of its mysteries and all of our discoveries.

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Speaker 1: Our goal in this podcast is to open our minds

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Speaker 1: to all of the craziest, biggest, deepest, most important questions

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Speaker 1: the one that frame the context of being human, the

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Speaker 1: ones that tell us what it means to be in

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Speaker 1: this universe and how this universe works. We tackle all

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Speaker 1: of those questions and we go right to the forefront

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Speaker 1: of scientific knowledge. We take you right to the edge

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Speaker 1: where scientists are currently working, and we explain all of

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Speaker 1: it to you in a way that we hope it

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Speaker 1: makes and maybe even occasionally makes you laugh. My co

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Speaker 1: host Orgy him the Creative PhD Comics, can't be here today,

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Speaker 1: so I'm gonna share with you one of my favorite

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Speaker 1: stories of scientific discovery. And I mentioned earlier on that

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Speaker 1: I have never discovered a new particle. That's not a true.

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Speaker 1: My career and particle physics spans from the mid nineteen

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Speaker 1: nineties till today, and in the mid nineteen nineties was

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Speaker 1: the discovery of the top cork or and I did

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Speaker 1: a really fun episode about that whole, amazing, hilarious, dramatic story.

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Speaker 1: But I just would have joined the field right when

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Speaker 1: that had already happened, So I wasn't around when the

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Speaker 1: top cork was discovered. I didn't get to participate in

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Speaker 1: that moment of discovery. I was, however, part of the

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Speaker 1: team that discovered the Higgs boson. But you have to understand,

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Speaker 1: this was a really big group of people, thousands of

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Speaker 1: thousands of people who all contributed little bits here and there,

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Speaker 1: and there wasn't really a dramatic moment when we said,

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Speaker 1: ah ha, the Higgs is there. It's solely emerged out

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Speaker 1: of the a a sort of the way a treasure

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Speaker 1: chest might be revealed in the sand of a beach,

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Speaker 1: as a tide pulls out inch by inch, showing you

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Speaker 1: more and more of it. That was sort of the

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Speaker 1: way the Higgs boson discovery went. We saw a little peak,

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Speaker 1: we thought it might be it. It got bigger and

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Speaker 1: bigger and bigger, and there was never really a moment

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Speaker 1: of than the official announcement when we could say, now

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Speaker 1: we have discovered the Higgs. But that sort of was

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Speaker 1: a bureaucratic choice and artificial choice. There was no single

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Speaker 1: aha moment. And part of that is because we knew

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Speaker 1: what we were looking for. We suspect that the Higgs

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Speaker 1: was there, we knew how to find it, we knew

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Speaker 1: how to look for it, we knew what to expect,

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Speaker 1: and so when we saw it, it was just sort

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Speaker 1: of this slow creeping realization that we had found what

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Speaker 1: we had been hunting. But that doesn't mean it's always

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Speaker 1: like that. There are moments of discovery in science. Usually

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Speaker 1: they happen when we're more surprised, when we see something

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Speaker 1: we didn't expect, when you go looking for one thing

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Speaker 1: and you find something else. Moments, for example, like the

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Speaker 1: discovery of the cosmic microwave back round that we talked

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Speaker 1: about a few episodes ago. Today, we're going to tell

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Speaker 1: the story of one of those moments when discovery came quickly,

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Speaker 1: when someone went looking for one thing and found something else,

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Speaker 1: something alarming and astonishing, a moment of insight about the universe. Actually,

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Speaker 1: we're gonna tell a story of two of those moments,

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Speaker 1: because this discovery has multiple parts, and for one of

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Speaker 1: those parts, we happen to have real historical audio of

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Speaker 1: those scientists realizing their discovery in real time as it happens,

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Speaker 1: so you'll get to hear what it actually sounds like

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Speaker 1: when scientists are astonished when they make a real life discovery.

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Speaker 1: So that's super fun, and for me, it's always really

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Speaker 1: interesting to try to understand what it was like to

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Speaker 1: make that discovery. You know, it's easy in hindsight to say,

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Speaker 1: all these things exist, here's how you look for them

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Speaker 1: that when did it bad? A boom but being done.

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Speaker 1: But you have to go back to what it was

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Speaker 1: like before we knew it was there, to put yourself

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Speaker 1: back in that mental position of ignorance, not knowing whether

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Speaker 1: something is out there, not understanding whether you live in

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Speaker 1: the universe where it's real or where it's just an idea,

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Speaker 1: not knowing which direction human knowledge and science will take.

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Speaker 1: Science is so easy in hindsight and so difficult in foresight.

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Speaker 1: When you stand in the forefront of human ignorance, you

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Speaker 1: don't know necessarily which way to go. So it's really

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Speaker 1: valuable to revisit these moments when we took a step forward,

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Speaker 1: when we went from ignorance to knowledge, and understand what

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Speaker 1: was required, how it happened, and the bravery it took

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Speaker 1: to make that claim to say I have found something new.

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Speaker 1: I now know something about the universe that no human

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Speaker 1: ever knew before. And so today we're gonna be telling

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Speaker 1: one of my favorite stories of discovery, one about a

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Speaker 1: really weird kind of star, a very fast, very dense,

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Speaker 1: very bizarre kind of star that we've talked about on

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Speaker 1: the podcast before and so today's episode we'll be answering

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Speaker 1: the question how we're pulsars discovered? And so, as usual,

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Speaker 1: before we dig into the topic and tell you the

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Speaker 1: story today, I wanted to know how much people already

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Speaker 1: knew about this sort of famous story. So I went

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Speaker 1: out and solicited volunteers from the internet to tell us

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Speaker 1: what they knew about various questions and science of this

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Speaker 1: being one of them. So thank you to all of

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Speaker 1: those who participated and give us their speculation without the

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Speaker 1: opportunity to look into any reference material whatsoever on the

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Speaker 1: honor system. Of course, if you'd like to participate and

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Speaker 1: hear your voice on the podcast in the future, please

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Speaker 1: don't be shy. I promise you it's fun. Send me

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Speaker 1: an email to questions at Daniel and Jorge dot com.

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Speaker 1: But in the meantime, think to yourself, do you know

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Speaker 1: the story of how pulsars were discovered? Here's what people

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Speaker 1: had to say. I am a d percent sure that

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Speaker 1: pulsels were discovered when they stuck a stepiscope pots to

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Speaker 1: the whole space telescope. I'm guessing pulsars were discovered by

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Speaker 1: scientists who observed these stars that were kind of flashing,

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Speaker 1: so dimming and brightening in these regular pulses. Hence the

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Speaker 1: name pulsar. I realized I just described what a pulsar is,

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Speaker 1: not how they were discovered, so sorry about that. UM.

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Speaker 1: For what a pulsar is, I would say it was

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Speaker 1: discovered as a rapidly blinking source of light in the sky. Um.

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Speaker 1: They were discovered by I think she was a graduate

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Speaker 1: student ince in the sixties. Something they were They discovered

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Speaker 1: through listening to some radio signals, and first they thought

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Speaker 1: there was extracted see in life, because they called that

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Speaker 1: little Green Men l g M. But I always confused

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Speaker 1: pulsars and quasars. I'm going to guess that someone saw

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Speaker 1: repetition of light in some part of the sky over

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Speaker 1: and over and that led to an investigation that found

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Speaker 1: the pulsars. Pulsars were discovered by a woman, and I

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Speaker 1: believe it was in the nineties seventies, but I'm not

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Speaker 1: sure how or why or where even There was a

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Speaker 1: woman astronomer radio astronomer whose name, unfortunately I cannot remember,

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Speaker 1: was doing some sort of sky survey when she noticed

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Speaker 1: a set of pulses that were incredibly regularly spaced. She

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Speaker 1: actually annotated them as l g M for Little Green Men.

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Speaker 1: That one time they thought it might have been discovery

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Speaker 1: of aliens, but later they discovered that it was actually

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Speaker 1: a rotating uh neutron star and the magnetic field was

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Speaker 1: exciting the gas molecules molecules around it and giving off

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Speaker 1: radio energy. Alright, so congratulations to our excellently informed listeners. Together,

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Speaker 1: they really do have most of the story there. There's

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Speaker 1: a lot of really insightful stuff and a lot of

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Speaker 1: bits of the story are there in pieces here and there.

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Speaker 1: So let's dig into it and to really understand how

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Speaker 1: pulsars were discovered, we have to understand, of course, first

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Speaker 1: what a pulsar is, how we came to the idea

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Speaker 1: of it existing in the universe, and that will help

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Speaker 1: us understand how it was seen and how we knew

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Speaker 1: what we were seeing, all right, So first of all,

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Speaker 1: what is a pulsar. A pulsar is a very very

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Speaker 1: compact object. Neutron stars and white dwarfs are more famous

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Speaker 1: as the sort of like densest things in the universe,

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Speaker 1: and a pulsar is a version of these. It's most

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Speaker 1: commonly considered to be a version of a neutron star,

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Speaker 1: but it can also be a white dwarf, but both

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Speaker 1: of them are essentially are the end points of stars.

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Speaker 1: Stars have these incredible life cycles where you start out

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Speaker 1: as a big molecular cloud, huge blob of gas and

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Speaker 1: dust that somehow shocked to collapse into a hot and

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Speaker 1: dense object a star, which burns for billions and billions

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Speaker 1: of years in this incredible, incredible balance between gravity that's

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Speaker 1: pulling it together, trying to turn it into a black

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Speaker 1: hole or something very very dense, and fusion which is

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Speaker 1: erupting and sending radiation out to prevent the collapse of

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Speaker 1: that star. And it always amazes me that these things

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Speaker 1: go on for so long, these two cosmic forces so different,

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Speaker 1: both so powerful, can be so balanced for so many

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Speaker 1: billions of years. Well, at some point the star gives

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Speaker 1: up because it's burned most of its fuel and its

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Speaker 1: core has become very very heavy, and it's filled with

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Speaker 1: things that it can no longer fuse. When the war

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Speaker 1: of the star is filled with iron, for example, I

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Speaker 1: using iron doesn't generate heat, it actually costs energy, so

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Speaker 1: it cools the star. So now the star no longer

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Speaker 1: has that power from fusion to resist gravity, and it collapses.

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Speaker 1: There's some intermediate stages in there will skip over, such

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Speaker 1: as it becoming a red giant, but depending on the

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Speaker 1: size of the star, this collapse generally triggers a supernova.

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Speaker 1: So you have this collapse where the materials racing inwards,

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Speaker 1: which then causes that back reaction outwards, a massive explosion

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Speaker 1: where a huge chunk of the stuff that used to

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Speaker 1: be the star is now spread out into a new nebula,

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Speaker 1: like a big sprawling cloud of gas and dust. At

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Speaker 1: the core of it, however, is a very dense, very

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Speaker 1: hot remnant, and that remnant can either be a white

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Speaker 1: dwarf or a neutron star or a black hole, depending

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Speaker 1: on the mass of the original star. So smaller stars

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Speaker 1: end up as white dwarfs, which are basically just like

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Speaker 1: huge hot chunks of metal that are resisting collapsing because

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Speaker 1: their fermions and they don't like to overlap too much,

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Speaker 1: or if they are larger, they become neutron stars, where

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Speaker 1: gravity now pushes them together and forces all of the

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Speaker 1: protons and the electrons together into forming new neutrons, and

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Speaker 1: you have this really weird material that's sort of like

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Speaker 1: the nucleus of an atom, but the size of a mountain.

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Speaker 1: So it's incredibly dense, incredibly weird stuff, something we even

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Speaker 1: still today do not understand in detail. And then, of course,

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Speaker 1: if the star is more massive, it would become a

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Speaker 1: black hole. So the gravity totally wins and nothing prevents

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Speaker 1: the collapse and it becomes a black hole. But it's

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Speaker 1: the first two categories that are more interested in. And

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Speaker 1: let's focus on the neutron star category because that's the

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Speaker 1: majority of pulsars. So you have this very dense object, right,

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Speaker 1: and the object is a huge chunk of the material

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Speaker 1: that used to be a star, not all of it.

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Speaker 1: Some of the material is lost in the supernova and

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Speaker 1: some of it remains in this cloud that surrounds the

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Speaker 1: neutron star. But this neutron star is a very very

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Speaker 1: dense object and very very small because gravity is really

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Speaker 1: pulled it together. And with that means is that it's

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Speaker 1: spinning really fast. Why is it spinning fast, Well, the

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Speaker 1: star itself was spinning because everything in the universe is spinning.

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Speaker 1: And the reason is simple is because angular momentum is conserved.

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Speaker 1: You know how momentum is conserved. If you push on something,

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Speaker 1: it stays in motion until something else pushes on it,

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Speaker 1: or if you don't push on something, it stays still

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Speaker 1: until something does push on it. That's conservation of momentum.

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Speaker 1: Those are Newton's laws. Well, there are similar laws for

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Speaker 1: angular momentum. That is that something spinning tends to keep spinning,

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Speaker 1: and to make something spin, you've gotta give it a push.

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Speaker 1: So if you leave something alone, it will keep spinning

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Speaker 1: the way it's always been spinning. Right, that's conservation of

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Speaker 1: angular momentum. And so the original gas cloud that formed

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Speaker 1: that star had some spin to it, and that spin

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Speaker 1: can't go away. It needs to stick around. And as

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Speaker 1: the gas cloud gets smaller and smaller and turns into

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Speaker 1: a star, the star spins faster. Now that might sound

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Speaker 1: like it violates conservation of because the momentum because it's

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Speaker 1: spinning faster. Right, Well, the velocity of the star's spin

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Speaker 1: is not what's conserved. It's the angular momentum, which is

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Speaker 1: the product of the velocity and their radius. So things

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Speaker 1: that are larger spin slower with the same angular momentum

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Speaker 1: as things that are smaller than spin faster. You know

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Speaker 1: this because if you're a figure skater and you pull

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Speaker 1: your arms in, you spin faster. You have the same

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Speaker 1: angular momentum. You're not pushing against anything to spin faster,

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Speaker 1: but you spin faster because your radius is smaller. So

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Speaker 1: to have the same angular momentum, you've got to go faster.

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Speaker 1: That's why the star spins faster than the original gas cloud.

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Speaker 1: And that's why the super compact, dense, little neutron star

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Speaker 1: that has a huge chunk of the star's mass but

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Speaker 1: is much much smaller. We're talking about something only kilometers

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Speaker 1: in size, you know, maybe ten fifteen kilometers, has to

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Speaker 1: be spinning really really fast to have the same angular

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Speaker 1: momentum as most of the original star. So that's why

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Speaker 1: these things are spinning so fast because they are so

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Speaker 1: small as they are so dense. In addition, some of

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Speaker 1: these things are highly magnetic. There's a magnetic field of

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Speaker 1: these stars, just like every star and most planets have

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Speaker 1: a magnetic field, and that's because the motion of charged

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Speaker 1: particles inside it. A neutron star is mostly neutrons, but

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Speaker 1: there are protons and there are electrons, and they are

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Speaker 1: moving around sometimes on the surface, and the flux of

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Speaker 1: the particles on the inside can create these magnetic fields.

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Speaker 1: So you have this object that's spinning really really fast,

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Speaker 1: and it has a magnetic field. In addition, it's generating

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Speaker 1: a huge amount of radiation. The magnetic field of the

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Speaker 1: thing is rotating, which generates an electric field which accelerates

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Speaker 1: the protons and the electrons on the surface of the

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Speaker 1: neutron star, and that creates a bunch of radiation because

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Speaker 1: when you accelerate particles, they radiate photons. So you have

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Speaker 1: this magnetic fields on this neutron star that's rotating and

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Speaker 1: is generating an electric field which pushes the electrons and

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Speaker 1: protons on the surface of the star, creating a lot

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Speaker 1: of radiation. And that radiation doesn't go in every direction

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Speaker 1: because there's a strong magnetic field. That radiation tends to

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Speaker 1: go along the magnetic north and the magnetic south because

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Speaker 1: magnetic fields are really good at bending the path of

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Speaker 1: charged particles. The reason that we don't get a lot

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Speaker 1: of radiation from space is because we have a magnetic

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Speaker 1: field here on Earth, and when particles come from space,

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Speaker 1: they are bent around those magnetic field lines. The magnetic

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Speaker 1: field lines are sort of like the lines on a

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Speaker 1: basketball right they run from north to south, and if

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Speaker 1: a particle comes from space, it gets bent by those

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Speaker 1: magnetic fields and goes out in another direction where sometimes

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Speaker 1: they loop around those magnetic field lines all the way

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Speaker 1: up to the north or the south pole, and then

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Speaker 1: they can slip in between the magnetic field lines. And

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Speaker 1: that's for example, why we have the Northern lights and

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Speaker 1: the Southern lights, because magnetic fields guide charged particles in

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Speaker 1: the same way. If you generate radiation on the surface

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Speaker 1: of the planet, it's also bound by those magnetic fields,

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Speaker 1: and so in this case, the magnetic fields are even

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Speaker 1: much more powerful, and essentially all of the radiation from

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Speaker 1: the neutron star gets guided towards the north or the

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Speaker 1: south pole of the magnetic field. So you get these

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Speaker 1: beams of radiation shooting off of this crazy neutron star.

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Speaker 1: Right like it's not crazy enough, it's already super hot,

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Speaker 1: super dense, super small, spinning, super fast, really magnetized, and

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Speaker 1: now on top of that, it's shining these two crazy

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Speaker 1: flashlights out into the universe, one from its magnetic north

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Speaker 1: pole and the other from its magnetic south pole. And

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Speaker 1: these beams don't come for free. They are very bright,

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Speaker 1: they cost a lot of energy, and this energy comes

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Speaker 1: from the spinning of the neutron star. Because that's what's

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Speaker 1: generating this electric field, the rotation of the magnetic field,

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Speaker 1: and eventually it's going to slow it down. Like these pulsars,

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Speaker 1: they generate these beams and they last for maybe ten

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Speaker 1: or a hundred million years, but they don't last for

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Speaker 1: their whole lifetime. At some point the beams turned off

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Speaker 1: because the neutron star has slowed down, it's not generating

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Speaker 1: that radiation anymore. What that means is that for most

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Speaker 1: of a lifetime, the pulsar is actually quiet. They don't

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Speaker 1: emit these beams, and so something like nine percent of

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Speaker 1: the pulsars out there aren't actually emitting any radiation anymore.

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Speaker 1: They are quiet. The universe is filled with dead pulsars,

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Speaker 1: pulsars that have gone quiet. So we've explained what a

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Speaker 1: pulsar is and how it emits these beams. But why

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Speaker 1: do we call it a pulsar. Are these beams themselves

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Speaker 1: like pulsing? Do they turn on and off? The beams

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Speaker 1: don't turn on and off. I mean, they last for

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Speaker 1: millions of years and they eventually fade, but they don't

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Speaker 1: like flicker on and off. The reason we call it

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Speaker 1: a pulsar is because we only see those beams as

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Speaker 1: they pass by the Earth, because the beam is shooting

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Speaker 1: up and down along the magnetic field lines. But that's

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Speaker 1: not necessarily the same as the axis that the pulsar

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Speaker 1: is spinning around. So if it were, if the magnetic

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Speaker 1: north and the magnetic south were the same as the

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Speaker 1: north and south of the actual stars, so it was

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Speaker 1: spinning around on the north pole, then it would always

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Speaker 1: be shooting the beam north and the beam south. However,

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Speaker 1: if instead the magnetic field is tilted so that it's

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Speaker 1: like spinning along one axis, but it's beams are shooting

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Speaker 1: off a little bit skewed, then when it spins around,

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Speaker 1: the direction of that beam changes right. It's like if

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Speaker 1: you're holding a flashlight and you point it straight up

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Speaker 1: and then spin, the direction of the flashlight doesn't change.

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Speaker 1: But if you hold a flashlight straight out and then

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Speaker 1: spin right, then what happens. Then Your flashlight's gonna sweep

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Speaker 1: around three sixty degrees every time you rotate. And what

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Speaker 1: does somebody see if they're standing in front of you

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Speaker 1: watching you spin, they see a flash. They see a

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Speaker 1: pulse of light only when the flashlight is pointed in

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Speaker 1: your direction. So it's this difference between the direction of

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Speaker 1: the pulsars magnetic field and it's actual spin axis, which

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Speaker 1: makes it a pulse. Are right, that's what makes it

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Speaker 1: appear to pulse. They don't actually pulse. They're sending bright

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Speaker 1: streams of light contain usually out into the universe until

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Speaker 1: they fade. But we see them pulsing because that beam

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Speaker 1: sweeps across Earth and that's what we see. So that's

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Speaker 1: what a pulsar is. An introduction to these weird things

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Speaker 1: in the universe. Next, we're gonna talk about why we

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Speaker 1: suspect that they might exist and how they were actually found.

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Speaker 1: But first let's take a quick break. All right, we're

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Speaker 1: back and we're talking about the incredible story of the

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Speaker 1: discovery of pulsars. And we reminded ourselves that pulsars are

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Speaker 1: a tiny, very hot, very dense, very quickly spinning stars

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Speaker 1: the left over heart of a supernova. They're shooting a

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Speaker 1: beam of light out into the universe, and they are

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Speaker 1: also spinning, and so that beam of light passes over

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Speaker 1: the Earth and looks like pulsations. It looks like pulses

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Speaker 1: from something out there in the universe. And before we

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Speaker 1: discovered these things, we had a suspicion that they existed.

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Speaker 1: People have been thinking about the life cycle of stars,

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Speaker 1: and in nineteen thirty four people suggested that when you

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Speaker 1: had a supernova, it might not all blow out into

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Speaker 1: the universe, that you might get this small, dense core

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Speaker 1: left over, and if so, it would have this really

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Speaker 1: weird state of matter. These neutrons would form, that would

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Speaker 1: be in a really dense state, this thing that's sort

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Speaker 1: of like nuclear matter, the things in the heart of atoms,

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Speaker 1: but now on the sides of like a mountain, something

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Speaker 1: kilometers wide. Imagine that the nucleus of an atom, but

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Speaker 1: kilometers wide. So this was a novelty, but nobody had

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Speaker 1: ever seen one before. We didn't know if neutron stars

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Speaker 1: existed in nineteen thirty four, and they would be difficult

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Speaker 1: to detect because these things don't have fusion anymore. They

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Speaker 1: don't glow the same way that very bright stars do.

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Speaker 1: So to see neutron stars seemed like a puzzle. But

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Speaker 1: then decades later people said, well, you know, they might

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Speaker 1: have very strong magnetic fields, and if so, they might

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Speaker 1: be rotating, and if so, then they might be pulsing.

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Speaker 1: And so this idea sort of came into existence in

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Speaker 1: the sixties idea the pulsars as weird, spinning, magnetized, beaming

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Speaker 1: light neutron stars might be out there. But you have

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Speaker 1: to remember that there are lots of crazy ideas for

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Speaker 1: what might be out there. The astronomy literature is filled

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Speaker 1: with people speculating maybe these things exist, maybe boson stars exist,

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Speaker 1: maybe these other things exist. Now, with a hindsight of history,

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Speaker 1: we can go back and trace the development of this

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Speaker 1: one thread of an idea that turned out to describe

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Speaker 1: something in the actual universe. But don't forget it was

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Speaker 1: buried at the time in a forest of other crazy,

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Speaker 1: wrong ideas about what might be out there in the universe.

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Speaker 1: You know, pulsars exist, and if you took a time

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Speaker 1: machine back to the sixties, you might say, I know

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Speaker 1: these things exist, and I know how to find them.

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Speaker 1: It's not actually that hard. But without the hindsight of

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Speaker 1: that history, of course, it's hard to pick the wheat

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Speaker 1: from the chaff. So let's get to the story of

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Speaker 1: how they were actually discovered. They were found by a

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Speaker 1: graduate student at the University of Cambridge, a woman named

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Speaker 1: Joscelynn Bell, and she was not looking for pulsars. In fact,

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Speaker 1: she wasn't looking for stars at all. She was trying

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Speaker 1: to study quasars. Quasars are at the heart of really

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Speaker 1: large galaxies. They are the accretion disks around black holes,

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Speaker 1: the stuff that has not yet fallen into the black

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Speaker 1: hole but is swirling around. And because of the tidal

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Speaker 1: forces and the incredible gravity, these things get really hot

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Speaker 1: and they radio a lot of light. And we had

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Speaker 1: seen these things, and we knew that they were very,

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Speaker 1: very far away, because these quasars have existed for a

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Speaker 1: long time. They were formed in the very early universe,

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Speaker 1: like a billion years after the Big Bang, but they're

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Speaker 1: still super duper bright. And for a long time they

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Speaker 1: were big mystery because people thought, well, what could it

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Speaker 1: be that is so incredibly bright and so far away,

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Speaker 1: so at its source, it's got to be like mind

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Speaker 1: bogglingly bright. What could that even be? People thought for

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Speaker 1: a long time, this was a mistake. It's not really

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Speaker 1: a thing. We must be misunderstanding how these things work.

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Speaker 1: And Jocelyn Bell was trying to understand these quasars. She

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Speaker 1: was trying to understand how these quasars twinkle, how they scintillate.

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Speaker 1: You know that when you look at a star in

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Speaker 1: the sky, you see a twinkling, and that's mostly because

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Speaker 1: the stuff between you and the star is interfering with

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Speaker 1: the star light. That's why planets, for example, don't twinkle,

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Speaker 1: but stars do because the light from the star has

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Speaker 1: to go really really far. So quasars kind of twinkle

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Speaker 1: as well. They do this thing called scintillation, and it's

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00:24:33,240 --> 00:24:36,479
Speaker 1: due to fluctuations in the densities of particles in the

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Speaker 1: solar wind. So the way we see quasars is not

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Speaker 1: by looking usually at visible light, but by looking at

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Speaker 1: radio waves. These things come from really really far away

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Speaker 1: and with their best seen in the radio spectrum. And

432
00:24:47,680 --> 00:24:50,960
Speaker 1: in the radio spectrum, an obstacle is the solar wind.

433
00:24:51,359 --> 00:24:54,480
Speaker 1: Remember that the Sun doesn't just shoot out photons. It

434
00:24:54,560 --> 00:24:57,639
Speaker 1: also shoots out a bunch of charge particles, protons and

435
00:24:57,680 --> 00:25:00,520
Speaker 1: electrons and other crazy stuff, and this is what we

436
00:25:00,600 --> 00:25:03,960
Speaker 1: call the solar wind. And when a radio photon enters

437
00:25:04,000 --> 00:25:07,679
Speaker 1: our solar system from somewhere really really far away, it

438
00:25:07,800 --> 00:25:11,239
Speaker 1: hits this barrage of radiation coming from the Sun and

439
00:25:11,359 --> 00:25:14,440
Speaker 1: interact with it. It's radio signal made of light and

440
00:25:14,640 --> 00:25:19,760
Speaker 1: electromagnetic radiation. Essentially, photons comes from these quasars billions of

441
00:25:19,840 --> 00:25:23,800
Speaker 1: years away, they sometimes get deflected or interfered with by

442
00:25:23,960 --> 00:25:26,119
Speaker 1: these particles in the solar wind, and so that's what

443
00:25:26,240 --> 00:25:29,399
Speaker 1: makes these quasars scintillate. So she wanted to study this

444
00:25:29,440 --> 00:25:32,120
Speaker 1: because she wanted to understand quasars. People at that time

445
00:25:32,240 --> 00:25:35,040
Speaker 1: didn't know that black holes were real, so they didn't

446
00:25:35,080 --> 00:25:38,439
Speaker 1: know what was powering these quasars. What could possibly be

447
00:25:38,560 --> 00:25:41,760
Speaker 1: generating so much radiation from so far away. So she

448
00:25:41,880 --> 00:25:45,280
Speaker 1: built a radio telescope. And a radio telescope is just

449
00:25:45,320 --> 00:25:48,280
Speaker 1: a bunch of antennas. But the thing about radio waves

450
00:25:48,359 --> 00:25:51,080
Speaker 1: is that their wavelength is very, very long. They could

451
00:25:51,080 --> 00:25:54,359
Speaker 1: be meters or hundreds of meters. So to capture a

452
00:25:54,520 --> 00:25:58,720
Speaker 1: radio photon, you need a big antenna, you need something large.

453
00:25:59,119 --> 00:26:01,239
Speaker 1: So she builds some thing which was four and a

454
00:26:01,280 --> 00:26:05,480
Speaker 1: half acres, Like this thing is big. She spent two years,

455
00:26:05,560 --> 00:26:09,280
Speaker 1: and for her, doing astronomy meant every day pounding fence

456
00:26:09,359 --> 00:26:13,160
Speaker 1: posts into the ground and stringing wire among them. Imagine

457
00:26:13,200 --> 00:26:15,920
Speaker 1: one of those old fashioned TV antennas. It was like

458
00:26:15,960 --> 00:26:18,360
Speaker 1: a grid of metal that could capture a signal. That's

459
00:26:18,480 --> 00:26:21,960
Speaker 1: essentially what she built. And she strung hundred and twenty

460
00:26:22,119 --> 00:26:25,480
Speaker 1: miles of wire over two years to build her radio

461
00:26:25,480 --> 00:26:28,800
Speaker 1: telescope to capture the signal from these quasars to look

462
00:26:28,840 --> 00:26:32,000
Speaker 1: at them scintillating. She wanted to see the fluctuations in

463
00:26:32,040 --> 00:26:34,840
Speaker 1: these signals. And that's really key because what she did

464
00:26:35,000 --> 00:26:37,600
Speaker 1: is get these radio signals and look at them and

465
00:26:37,640 --> 00:26:41,560
Speaker 1: develop her own personal sense for what this data should

466
00:26:41,600 --> 00:26:45,800
Speaker 1: look like. She was looking for characteristic wiggles changes in

467
00:26:45,840 --> 00:26:48,840
Speaker 1: this data as they studied the pulsar. And this is

468
00:26:48,880 --> 00:26:51,600
Speaker 1: back in the day before they had computers and before

469
00:26:51,640 --> 00:26:54,120
Speaker 1: people could just like you know, dump the data onto

470
00:26:54,200 --> 00:26:57,040
Speaker 1: the screen and analyze it bump bump bump. Her data

471
00:26:57,080 --> 00:27:00,719
Speaker 1: came out directly onto a printer like her radio telescope

472
00:27:01,000 --> 00:27:03,720
Speaker 1: captured this turned it into an electrical signal which was

473
00:27:03,880 --> 00:27:07,000
Speaker 1: directly sent to a printer which dumped it onto paper.

474
00:27:07,359 --> 00:27:10,760
Speaker 1: So her output from her telescope was stored on a

475
00:27:10,880 --> 00:27:14,159
Speaker 1: hundred feet per day of printer paper, which is like

476
00:27:14,400 --> 00:27:17,120
Speaker 1: came out steadily and she would stand there and look

477
00:27:17,200 --> 00:27:18,840
Speaker 1: at it. She would get to know it. She was

478
00:27:18,880 --> 00:27:22,240
Speaker 1: like a natural neural network where she learned if I'm

479
00:27:22,240 --> 00:27:24,280
Speaker 1: looking over here that I'm going to see this thing

480
00:27:24,400 --> 00:27:26,400
Speaker 1: which we're pointing at the sun, and I'm gonna see

481
00:27:26,400 --> 00:27:28,359
Speaker 1: this kind of radio waves. And this isn't the kind

482
00:27:28,359 --> 00:27:30,480
Speaker 1: of thing that she could easily point right. This thing

483
00:27:30,560 --> 00:27:33,600
Speaker 1: is just something you build in the ground. But the

484
00:27:33,640 --> 00:27:36,359
Speaker 1: earth turns, and as the Earth turns, this thing is

485
00:27:36,440 --> 00:27:39,800
Speaker 1: essentially pointed in a new direction. She herself is like

486
00:27:39,920 --> 00:27:43,959
Speaker 1: sweeping her instrument across the sky, examining different parts of

487
00:27:43,960 --> 00:27:47,480
Speaker 1: the universe. And you can get some directional information from

488
00:27:47,520 --> 00:27:50,680
Speaker 1: a radio antenna based on like when the signal arrives,

489
00:27:50,720 --> 00:27:53,040
Speaker 1: does it arrive first on the eastern part of the

490
00:27:53,080 --> 00:27:55,760
Speaker 1: antenna or first on the western part of the antenna.

491
00:27:55,920 --> 00:27:58,560
Speaker 1: But it's not great at telling where something is coming

492
00:27:58,600 --> 00:28:01,840
Speaker 1: from exactly. So she came really good analyzing these signals,

493
00:28:01,920 --> 00:28:06,840
Speaker 1: and then one day, November nineteen sixty seven, she saw

494
00:28:06,880 --> 00:28:09,520
Speaker 1: the signal that she did not understand, something she had

495
00:28:09,600 --> 00:28:13,640
Speaker 1: never seen before. What she saw were pulses separated by

496
00:28:13,800 --> 00:28:16,840
Speaker 1: one and the third seconds. So it was like whoop,

497
00:28:17,760 --> 00:28:22,280
Speaker 1: poop poop, and she would get these pulses of radio waves,

498
00:28:22,320 --> 00:28:25,600
Speaker 1: and the regularity of it, the exact distance between the

499
00:28:25,640 --> 00:28:28,199
Speaker 1: pulses is what made it seem really weird. And at

500
00:28:28,240 --> 00:28:30,800
Speaker 1: first she thought, oh, this must be a signal from

501
00:28:30,920 --> 00:28:33,960
Speaker 1: something here. On Earth, because, of course, there are lots

502
00:28:34,000 --> 00:28:38,120
Speaker 1: of sources of radio waves here on Earth. Almost everything

503
00:28:38,120 --> 00:28:42,240
Speaker 1: we do with our electronics generates radio noise. Every time

504
00:28:42,280 --> 00:28:44,600
Speaker 1: you turn on your television, certainly every time you use

505
00:28:44,600 --> 00:28:47,880
Speaker 1: your cell phone, and of course there are radio transmitters

506
00:28:47,920 --> 00:28:50,800
Speaker 1: all over the planet. And so first she had to

507
00:28:50,880 --> 00:28:55,160
Speaker 1: rule out various sources of human interference, like other radio astronomers,

508
00:28:55,240 --> 00:28:57,959
Speaker 1: people sending pulses off the Moon to measure the distance

509
00:28:58,000 --> 00:29:02,640
Speaker 1: to the Moon, television signals, beeps from orbiting satellites, even

510
00:29:02,760 --> 00:29:06,640
Speaker 1: like you know, possible effects from large corrugated metal buildings

511
00:29:06,720 --> 00:29:09,640
Speaker 1: near the telescopes. She went through this whole list, and

512
00:29:09,680 --> 00:29:11,400
Speaker 1: you gotta do that when you see something weird in

513
00:29:11,400 --> 00:29:15,160
Speaker 1: your data, you gotta first look for the boring explanation like, oh, well,

514
00:29:15,440 --> 00:29:18,200
Speaker 1: maybe I'm just measuring what happens when somebody turns on

515
00:29:18,280 --> 00:29:20,800
Speaker 1: the microwave in the break room or something like that.

516
00:29:20,840 --> 00:29:23,600
Speaker 1: You don't go straight to I've discovered something new in

517
00:29:23,640 --> 00:29:26,400
Speaker 1: the universe. So she very carefully went through all these

518
00:29:26,440 --> 00:29:30,880
Speaker 1: different explanations and eventually even borrowed somebody else's radio telescope

519
00:29:30,960 --> 00:29:33,840
Speaker 1: to confirm her observations. She wanted to make sure it

520
00:29:33,920 --> 00:29:36,880
Speaker 1: wasn't just like some weird blip in her telescope, so

521
00:29:36,920 --> 00:29:39,480
Speaker 1: she knew it wasn't just her telescope. She ruled out

522
00:29:39,520 --> 00:29:43,200
Speaker 1: all sources of human earth bound interference, and she saw

523
00:29:43,240 --> 00:29:46,240
Speaker 1: that it tracted with a particular location in the sky.

524
00:29:46,760 --> 00:29:48,600
Speaker 1: And that's a great clue that tells you that it's

525
00:29:48,640 --> 00:29:51,520
Speaker 1: not from Earth, because if it's from Earth, then it

526
00:29:51,560 --> 00:29:54,560
Speaker 1: doesn't matter which direction the Earth is pointed. If it's

527
00:29:54,640 --> 00:29:57,040
Speaker 1: not from Earth, then you will only see it when

528
00:29:57,080 --> 00:29:59,640
Speaker 1: the Earth is pointed in a certain direction, only when

529
00:29:59,680 --> 00:30:02,840
Speaker 1: the mess it itself sweeped across your radio telescope. So

530
00:30:02,880 --> 00:30:06,080
Speaker 1: where did their minds go? The strange regularity of it,

531
00:30:06,160 --> 00:30:08,760
Speaker 1: the fact that it came like every one and a

532
00:30:08,920 --> 00:30:12,920
Speaker 1: third seconds, made them think not of some new after

533
00:30:13,040 --> 00:30:17,160
Speaker 1: physical object, because nature is not often that precise, right.

534
00:30:17,480 --> 00:30:20,000
Speaker 1: Nature is messy. When you go out into the world.

535
00:30:20,040 --> 00:30:23,600
Speaker 1: You don't see like rocks that are exactly square. You

536
00:30:23,640 --> 00:30:27,480
Speaker 1: don't see like ten rocks exactly the same size. You

537
00:30:27,520 --> 00:30:29,840
Speaker 1: don't see the sort of regular patterns. I mean, sometimes

538
00:30:29,840 --> 00:30:33,440
Speaker 1: you do in crystals and other places, but nature is

539
00:30:33,520 --> 00:30:37,600
Speaker 1: more often messy than precise and regular. So their media

540
00:30:37,680 --> 00:30:42,280
Speaker 1: thought was like, wow, maybe this is alien intelligence, you know,

541
00:30:42,400 --> 00:30:45,480
Speaker 1: she says, quote, we did not really believe that we

542
00:30:45,520 --> 00:30:48,760
Speaker 1: had picked up signals from another civilization, but obviously the

543
00:30:48,840 --> 00:30:51,640
Speaker 1: idea had crossed our minds, and we had no proof

544
00:30:51,840 --> 00:30:54,920
Speaker 1: that it was an entirely natural radio emission. It is

545
00:30:54,960 --> 00:30:58,040
Speaker 1: an interesting problem if one thinks one may have detected

546
00:30:58,080 --> 00:31:00,680
Speaker 1: life elsewhere in the universe, how does one announced the

547
00:31:00,720 --> 00:31:04,120
Speaker 1: results responsibly? So they really didn't know what they had.

548
00:31:04,440 --> 00:31:06,960
Speaker 1: They were wondering, is this something weird and new? Are

549
00:31:07,000 --> 00:31:10,400
Speaker 1: these aliens? Or is this some natural source of radio

550
00:31:10,440 --> 00:31:14,560
Speaker 1: emission that's weirdly regular. So in their internal notes they

551
00:31:14,560 --> 00:31:18,160
Speaker 1: called this thing l g M, one for Little Green Men.

552
00:31:18,480 --> 00:31:21,680
Speaker 1: And so here you can see the process of discovery

553
00:31:21,760 --> 00:31:25,840
Speaker 1: in motion, like there existed in the literature, the speculation

554
00:31:25,880 --> 00:31:29,040
Speaker 1: that these things might be out there, that spinning neutron

555
00:31:29,120 --> 00:31:33,160
Speaker 1: stars might generate pulses, and here they are discovering pulses

556
00:31:33,240 --> 00:31:36,840
Speaker 1: in the radio spectrum, essentially exactly what was predicted. But

557
00:31:36,920 --> 00:31:39,760
Speaker 1: they couldn't put it together because, as we mentioned before,

558
00:31:40,240 --> 00:31:42,680
Speaker 1: there are lots of predictions out there in the literature,

559
00:31:42,960 --> 00:31:45,960
Speaker 1: only in hindsights you know exactly who to listen to.

560
00:31:46,280 --> 00:31:50,040
Speaker 1: It's like picking one of Nostradamis's predictions. Right, most of

561
00:31:50,080 --> 00:31:52,640
Speaker 1: them are nonsense, and if you look back through all

562
00:31:52,680 --> 00:31:54,640
Speaker 1: of them, you can always find one that seems to

563
00:31:54,680 --> 00:31:57,680
Speaker 1: make sense. So what they did was they kept looking,

564
00:31:58,080 --> 00:32:01,480
Speaker 1: and pretty soon they found in other pulsars somewhere else

565
00:32:01,560 --> 00:32:05,520
Speaker 1: in the sky. And I told him it's probably not aliens,

566
00:32:05,680 --> 00:32:09,720
Speaker 1: because their signals coming from two very different, very distant

567
00:32:09,760 --> 00:32:13,440
Speaker 1: locations in the universe, so probably it's a natural source.

568
00:32:13,640 --> 00:32:16,760
Speaker 1: And then by Christmas of nineteen sixty seven, right just

569
00:32:16,880 --> 00:32:21,000
Speaker 1: like weeks after the first discovery, they had found four

570
00:32:21,120 --> 00:32:24,760
Speaker 1: of these things, so four pulsars, and early the next

571
00:32:24,840 --> 00:32:27,400
Speaker 1: year they publicized their results and they wrote a nice

572
00:32:27,440 --> 00:32:31,240
Speaker 1: paper and this was a huge discovery, and then everybody

573
00:32:31,240 --> 00:32:34,200
Speaker 1: with the radio telescope started looking at these things, like, wow,

574
00:32:34,280 --> 00:32:36,840
Speaker 1: oh my gosh, these things are out there. The incredible

575
00:32:36,880 --> 00:32:39,000
Speaker 1: thing is that once you know to look for them,

576
00:32:39,120 --> 00:32:42,520
Speaker 1: they're not that hard to find. Pulsars are pretty bright.

577
00:32:42,720 --> 00:32:46,480
Speaker 1: Radio telescopes were kind of new. Optical astronomy was dominant

578
00:32:46,480 --> 00:32:48,280
Speaker 1: at the time, but there were a lot of radio

579
00:32:48,280 --> 00:32:52,400
Speaker 1: telescopes out there, and by the end of nineteen dozens

580
00:32:52,440 --> 00:32:55,760
Speaker 1: of these things had been found, and it was another scientist,

581
00:32:55,880 --> 00:32:58,920
Speaker 1: a guy named Thomas Gold, that put the story together,

582
00:32:59,000 --> 00:33:03,760
Speaker 1: who said, Ah, these pulsars are the rotating neutron stars

583
00:33:03,760 --> 00:33:06,400
Speaker 1: that we've been thinking about. What these folks have seen

584
00:33:06,520 --> 00:33:09,960
Speaker 1: out there in the universe is exactly what we thought

585
00:33:10,120 --> 00:33:13,760
Speaker 1: might happen in some circumstances at the end of a supernova.

586
00:33:13,840 --> 00:33:16,360
Speaker 1: So that was a really incredible moment to say, like, Wow,

587
00:33:16,760 --> 00:33:20,120
Speaker 1: these things, these crazy, weird little blobs that we've predicted

588
00:33:20,280 --> 00:33:23,240
Speaker 1: might be there as like the tombstone on the end

589
00:33:23,320 --> 00:33:26,560
Speaker 1: of a supernova, actually are out there and they do

590
00:33:26,600 --> 00:33:29,719
Speaker 1: this weird thing that lets us find them. I think

591
00:33:29,760 --> 00:33:32,160
Speaker 1: the discovery that really put a pin in it was

592
00:33:32,200 --> 00:33:34,440
Speaker 1: the discovery of a pulsar at the heart of the

593
00:33:34,520 --> 00:33:37,960
Speaker 1: crab Nebula. Crab Nebula is a huge cloud of gas

594
00:33:37,960 --> 00:33:41,320
Speaker 1: and dust. It's the remnant of an old supernova star

595
00:33:41,440 --> 00:33:44,280
Speaker 1: that blew up and spread most of its stuff out

596
00:33:44,280 --> 00:33:46,360
Speaker 1: there in the universe. So then when we looked with

597
00:33:46,400 --> 00:33:48,480
Speaker 1: the radio and we saw that at the heart of

598
00:33:48,560 --> 00:33:52,360
Speaker 1: crab Nebula was a pulsar, we thought, that's what this is,

599
00:33:52,400 --> 00:33:55,240
Speaker 1: and that completes the story that tells us that at

600
00:33:55,240 --> 00:33:58,479
Speaker 1: the heart of many nebula there may be these neutron stars.

601
00:33:58,720 --> 00:34:01,600
Speaker 1: Not all of them become all stars, but pulsars tell

602
00:34:01,720 --> 00:34:04,920
Speaker 1: us that the neutron stars are there, that this supernova

603
00:34:05,000 --> 00:34:08,360
Speaker 1: remnant has this hard little nub at the core of it.

604
00:34:08,680 --> 00:34:11,120
Speaker 1: But remember that we're using radio waves so far to

605
00:34:11,160 --> 00:34:14,480
Speaker 1: find these pulsars, and radio waves are not very good

606
00:34:14,520 --> 00:34:17,319
Speaker 1: at telling the direction of a signal. It's not like

607
00:34:17,360 --> 00:34:22,040
Speaker 1: an optical telescope, where the photons of very short frequencies nanometers,

608
00:34:22,080 --> 00:34:24,080
Speaker 1: and you can capture them with a telescope point in

609
00:34:24,120 --> 00:34:26,880
Speaker 1: one specific direction and you can tell exactly where on

610
00:34:26,880 --> 00:34:29,560
Speaker 1: the lens it hit. These things are captured by very

611
00:34:29,680 --> 00:34:32,359
Speaker 1: large antenna and it's hard to tell what direction they're

612
00:34:32,360 --> 00:34:34,920
Speaker 1: coming from. So while we say we saw a pulsar

613
00:34:34,960 --> 00:34:37,080
Speaker 1: in the direction of the crab nebula, it's not like

614
00:34:37,120 --> 00:34:40,319
Speaker 1: we could really pin down its location exactly. So there's

615
00:34:40,360 --> 00:34:43,080
Speaker 1: a second part of this discovery story, a part that

616
00:34:43,200 --> 00:34:45,719
Speaker 1: was caught on audio tape that I want to share

617
00:34:45,800 --> 00:35:01,799
Speaker 1: with you. But first let's take another break, all right.

618
00:35:01,840 --> 00:35:04,080
Speaker 1: So we are in the late sixties and the field

619
00:35:04,120 --> 00:35:07,680
Speaker 1: of astronomy was very excited because people had been discovering pulsars.

620
00:35:07,880 --> 00:35:10,840
Speaker 1: But these pulsars had been seen in the radio frequency,

621
00:35:11,000 --> 00:35:13,399
Speaker 1: which means they were hard to pin down exactly where

622
00:35:13,440 --> 00:35:16,399
Speaker 1: they were, and people were wondering, are their pulsars out

623
00:35:16,400 --> 00:35:18,680
Speaker 1: there where? The beams of light that they are shooting

624
00:35:18,960 --> 00:35:22,160
Speaker 1: are visible light, not just a radio noise, but like

625
00:35:22,280 --> 00:35:26,680
Speaker 1: actual visible beams that our eyes and our telescopes could see. Well,

626
00:35:26,719 --> 00:35:29,640
Speaker 1: most pulsars, we think are brightest in the radio or

627
00:35:29,760 --> 00:35:31,839
Speaker 1: in the X ray. But the idea was that there

628
00:35:31,880 --> 00:35:34,359
Speaker 1: might be some optical pulsars. So there are a couple

629
00:35:34,360 --> 00:35:37,359
Speaker 1: of theorists named John Cook and Mike Disney, and these

630
00:35:37,360 --> 00:35:40,680
Speaker 1: were not experienced astronomers, but they were curious about whether

631
00:35:40,800 --> 00:35:42,960
Speaker 1: or not you could see one of these pulsars in

632
00:35:43,000 --> 00:35:45,520
Speaker 1: the optical So they decided, hey, let's give this thing

633
00:35:45,560 --> 00:35:48,680
Speaker 1: a shot. Let's sign up for some telescope time pointed

634
00:35:48,680 --> 00:35:50,759
Speaker 1: at one of these pulsars and see if we can

635
00:35:50,800 --> 00:35:54,359
Speaker 1: see any flashes. So these guys not experimentalists, right, they

636
00:35:54,360 --> 00:35:56,600
Speaker 1: didn't really know how to use a telescope. This their

637
00:35:56,640 --> 00:36:01,200
Speaker 1: first time using like real serious astronomical scientific equipment, and

638
00:36:01,239 --> 00:36:03,440
Speaker 1: they went down to kid Peak near Tucson, and they

639
00:36:03,440 --> 00:36:05,560
Speaker 1: signed up for a couple of days of observing time,

640
00:36:05,760 --> 00:36:07,680
Speaker 1: and what they had going for them was that they

641
00:36:07,680 --> 00:36:09,920
Speaker 1: were going to point this thing at the crab nebula,

642
00:36:10,000 --> 00:36:13,120
Speaker 1: and they already knew the frequency of the pulsar, so

643
00:36:13,120 --> 00:36:16,239
Speaker 1: they knew like what frequency of light flashes to look for.

644
00:36:16,440 --> 00:36:19,000
Speaker 1: So what they did is they pointed this telescope at

645
00:36:19,000 --> 00:36:21,520
Speaker 1: the crab nebula and then they looked at the light

646
00:36:21,600 --> 00:36:23,920
Speaker 1: that came in. But remember that this again was before

647
00:36:24,000 --> 00:36:28,399
Speaker 1: like dedicated computers where you could rapidly inflexibly analyze your data.

648
00:36:28,480 --> 00:36:31,320
Speaker 1: But they needed was some sort of like dedicated electronics

649
00:36:31,400 --> 00:36:34,719
Speaker 1: that could turn their flashes of light into blips that

650
00:36:34,800 --> 00:36:36,799
Speaker 1: they could study. So there was a guy there who

651
00:36:36,880 --> 00:36:39,400
Speaker 1: was really good electronics, and he happened to have exactly

652
00:36:39,440 --> 00:36:42,240
Speaker 1: what they needed. So they could plug their telescope into

653
00:36:42,280 --> 00:36:44,799
Speaker 1: this thing and it would analyze the frequency, like the

654
00:36:44,880 --> 00:36:47,680
Speaker 1: time between blips and make a little plot from them

655
00:36:47,800 --> 00:36:50,080
Speaker 1: on a very small screen. So it's sort of like

656
00:36:50,120 --> 00:36:53,680
Speaker 1: a dedicated computer exactly to do this. They happen to

657
00:36:53,680 --> 00:36:56,440
Speaker 1: stumble across this guy who had exactly this equipment to

658
00:36:56,520 --> 00:36:58,719
Speaker 1: do what they needed. So they went out there for

659
00:36:58,760 --> 00:37:01,120
Speaker 1: their first day. They were very ided, thinking, Wow, maybe

660
00:37:01,120 --> 00:37:03,440
Speaker 1: we're going to discover something, and they turned it on

661
00:37:03,640 --> 00:37:05,880
Speaker 1: and they saw nothing. And but they didn't know at

662
00:37:05,880 --> 00:37:07,520
Speaker 1: the time was that they had made a mistake in

663
00:37:07,600 --> 00:37:10,120
Speaker 1: their calculations and they had like tweaked the knobs on

664
00:37:10,160 --> 00:37:12,919
Speaker 1: this thing wrong, so they shouldn't have seen anything because

665
00:37:12,920 --> 00:37:15,600
Speaker 1: they were looking at the wrong sort of frequency spectrum.

666
00:37:15,680 --> 00:37:18,760
Speaker 1: The next two nights that they had were both cloudy,

667
00:37:18,840 --> 00:37:21,160
Speaker 1: and so they lost all of their observing time and

668
00:37:21,200 --> 00:37:23,520
Speaker 1: they never would have seen this thing that hadn't been

669
00:37:23,680 --> 00:37:26,799
Speaker 1: for somebody else's bad luck. The person with the telescope

670
00:37:26,880 --> 00:37:29,880
Speaker 1: next after them, his wife got sick, so he decided

671
00:37:29,920 --> 00:37:31,560
Speaker 1: he was going to stay home and take care of her,

672
00:37:31,880 --> 00:37:34,960
Speaker 1: and he gave them his telescope time, so they got

673
00:37:35,000 --> 00:37:37,640
Speaker 1: an extra bonus of a couple of days of observing

674
00:37:37,680 --> 00:37:40,360
Speaker 1: time that they didn't expect to get. And the clouds

675
00:37:40,400 --> 00:37:42,960
Speaker 1: cleared and they had a beautiful night, and they set

676
00:37:43,000 --> 00:37:46,480
Speaker 1: their thing correctly. And they also had a tape recorder

677
00:37:46,560 --> 00:37:50,720
Speaker 1: running which recorded their conversation as well as the data

678
00:37:50,880 --> 00:37:54,040
Speaker 1: coming from the telescope. So this little box not only

679
00:37:54,080 --> 00:37:56,279
Speaker 1: makes a lit depiction on their screen that shows from

680
00:37:56,280 --> 00:37:59,279
Speaker 1: the frequency, it also made a little tick for every blip,

681
00:37:59,360 --> 00:38:01,920
Speaker 1: so you'll hear those ticks. On this tape, you'll also

682
00:38:02,000 --> 00:38:17,120
Speaker 1: hear them reacting in real time to the discovery they're making. Hey, ah,

683
00:38:18,400 --> 00:38:27,359
Speaker 1: I was supposed heping ca. So you hear them saying

684
00:38:27,400 --> 00:38:29,680
Speaker 1: that it's bang in the middle of the period. Remember

685
00:38:29,719 --> 00:38:32,160
Speaker 1: that they knew what to look for. They knew the

686
00:38:32,320 --> 00:38:35,000
Speaker 1: period of this pulsar. They knew their frequency of which

687
00:38:35,040 --> 00:38:38,040
Speaker 1: it should flash, so they were looking for a repeated

688
00:38:38,160 --> 00:38:40,839
Speaker 1: pattern of flashes with just the right period. They had

689
00:38:41,120 --> 00:38:43,520
Speaker 1: zoomed in on exactly what they were hoping to see,

690
00:38:43,719 --> 00:38:46,200
Speaker 1: but of course they never knew whether the universe would

691
00:38:46,200 --> 00:38:48,480
Speaker 1: show it to them or whether it wouldn't. Hear the

692
00:38:48,480 --> 00:39:04,319
Speaker 1: rest of their recording really looks something mhm too, Oh yeah,

693
00:39:12,080 --> 00:39:17,640
Speaker 1: it look so you can hear literally the excitement in

694
00:39:17,719 --> 00:39:20,000
Speaker 1: their voice. One of them is astonished, look at that

695
00:39:20,120 --> 00:39:22,759
Speaker 1: bleeding pulse, and the other one is like, I can't

696
00:39:22,760 --> 00:39:25,600
Speaker 1: believe this is happening right now, it's getting bigger and bigger.

697
00:39:25,760 --> 00:39:28,440
Speaker 1: You can see them discovering it. You can hear in

698
00:39:28,640 --> 00:39:32,279
Speaker 1: their voices that they're realizing that they've caught it, that

699
00:39:32,440 --> 00:39:36,400
Speaker 1: they've seen this pulsar flickering invisible light, that they've pointed

700
00:39:36,480 --> 00:39:39,799
Speaker 1: this telescope at this weird, far away object and they've

701
00:39:39,880 --> 00:39:42,719
Speaker 1: caught it doing its thing. So that's a super fun

702
00:39:42,800 --> 00:39:45,719
Speaker 1: little follow up discovery. They published that paper, and this

703
00:39:45,880 --> 00:39:47,960
Speaker 1: must have been a really fun moment for these guys,

704
00:39:48,000 --> 00:39:50,319
Speaker 1: because again, this is the first time they ever went

705
00:39:50,400 --> 00:39:52,600
Speaker 1: to a telescope. This is the first time they ever

706
00:39:52,680 --> 00:39:55,160
Speaker 1: like looked out into the universe. Most of their science

707
00:39:55,239 --> 00:39:57,120
Speaker 1: was done with pencil and paper and just sort of

708
00:39:57,200 --> 00:39:59,319
Speaker 1: thinking about what might be out there. And so I'm

709
00:39:59,360 --> 00:40:01,919
Speaker 1: glad they got to go out there and actually experienced

710
00:40:02,000 --> 00:40:04,880
Speaker 1: this moment of discovery. And it also really helped us

711
00:40:05,000 --> 00:40:08,719
Speaker 1: understand what these pulsars were because with the optical telescope

712
00:40:08,880 --> 00:40:11,560
Speaker 1: with a visible light, you could really pin down exactly

713
00:40:11,640 --> 00:40:13,879
Speaker 1: where this thing was, and we knew then that really

714
00:40:14,040 --> 00:40:16,200
Speaker 1: was at the heart of the crab nebula and it

715
00:40:16,320 --> 00:40:20,000
Speaker 1: really was a pulsar. So very exciting discovery and very

716
00:40:20,120 --> 00:40:23,800
Speaker 1: quickly appreciated, of course by the scientific community. And in

717
00:40:24,000 --> 00:40:28,360
Speaker 1: nineteen seventy four, just a few years later, Jocelyn Bell's

718
00:40:28,400 --> 00:40:31,960
Speaker 1: advisor is the first astronomer to ever win the Nobel

719
00:40:32,080 --> 00:40:36,120
Speaker 1: Prize in physics. That's right, her advisor won the Nobel

720
00:40:36,200 --> 00:40:38,960
Speaker 1: Prize now, of course he was involved, right, You know,

721
00:40:39,239 --> 00:40:42,440
Speaker 1: a graduate student never works alone. He gave lots of guidance,

722
00:40:42,640 --> 00:40:45,839
Speaker 1: lots of ideas, probably provided the funding. But it's clear

723
00:40:46,000 --> 00:40:48,480
Speaker 1: that she's the one who made the discovery. She built

724
00:40:48,520 --> 00:40:50,480
Speaker 1: that thing, She was out there day to day, she

725
00:40:50,719 --> 00:40:52,920
Speaker 1: saw it in the data. And there's a lot of

726
00:40:53,000 --> 00:40:56,120
Speaker 1: discussion these days about why she was left out of it.

727
00:40:56,680 --> 00:40:59,000
Speaker 1: It's because she was a student. While there are lots

728
00:40:59,040 --> 00:41:02,600
Speaker 1: of other cases when a student participated in discovery and

729
00:41:02,760 --> 00:41:06,760
Speaker 1: was included in the Nobel Prize. Discovery. Wholes and Taylor,

730
00:41:06,800 --> 00:41:10,240
Speaker 1: for example, was a graduate student advisor pair that discovered

731
00:41:10,320 --> 00:41:13,359
Speaker 1: binary pulsars just a couple of decades later, and they

732
00:41:13,400 --> 00:41:16,120
Speaker 1: were both given the Nobel Prize even though one of

733
00:41:16,160 --> 00:41:19,520
Speaker 1: them was a graduate student. Of course, there's the question

734
00:41:19,600 --> 00:41:21,839
Speaker 1: of whether or not it was sexism. In the history

735
00:41:21,840 --> 00:41:24,680
Speaker 1: of the Nobel Prizes, very few women have been given

736
00:41:24,760 --> 00:41:27,440
Speaker 1: the prize and many have been qualified, so it seems

737
00:41:27,440 --> 00:41:30,400
Speaker 1: like an obvious case of injustice. Burnell herself is very

738
00:41:30,440 --> 00:41:33,440
Speaker 1: gracious about it. She recently was given the Breakthrough Prize

739
00:41:33,480 --> 00:41:36,200
Speaker 1: and Fundamental Physics, which comes with millions of dollars, which

740
00:41:36,280 --> 00:41:39,160
Speaker 1: she then donated to advancing the cause of having more

741
00:41:39,280 --> 00:41:41,840
Speaker 1: women in physics. But of course she didn't know that.

742
00:41:41,920 --> 00:41:44,239
Speaker 1: The journalists didn't ask her science questions. They tended to

743
00:41:44,239 --> 00:41:46,799
Speaker 1: ask her questions about like how many boyfriends she had.

744
00:41:47,080 --> 00:41:50,120
Speaker 1: But this kicked off a whole really exciting era of astronomy,

745
00:41:50,200 --> 00:41:53,080
Speaker 1: because every time you discover something new out there in

746
00:41:53,160 --> 00:41:55,320
Speaker 1: the universe, it gives you another handle, it gives you

747
00:41:55,400 --> 00:41:58,560
Speaker 1: a way to learn things. It reveals new things about

748
00:41:58,600 --> 00:42:01,239
Speaker 1: the universe that you didn't know before. And just a

749
00:42:01,320 --> 00:42:05,000
Speaker 1: few years after that, we discovered things like millisecond pulsars.

750
00:42:05,400 --> 00:42:08,200
Speaker 1: These are things that's been around so fast that we

751
00:42:08,400 --> 00:42:11,360
Speaker 1: see a pulse from them, not every second, but every

752
00:42:11,600 --> 00:42:14,760
Speaker 1: mill a second. So these stars are spending a thousand

753
00:42:14,960 --> 00:42:19,319
Speaker 1: times faster than the original pulsar spun right every one

754
00:42:19,360 --> 00:42:23,960
Speaker 1: point six seconds. This incredible, enormous dense object spins around.

755
00:42:24,320 --> 00:42:27,280
Speaker 1: These things are moving really really fast, spinning like tens

756
00:42:27,400 --> 00:42:30,759
Speaker 1: of thousands of times per minute. The fastest pulsar we've

757
00:42:30,800 --> 00:42:32,840
Speaker 1: ever seen, we talked about on our episode about the

758
00:42:32,920 --> 00:42:36,600
Speaker 1: fastest spinning things in the universe is sixteen kilometers in

759
00:42:36,760 --> 00:42:39,480
Speaker 1: radius and the surface of it is moving at a

760
00:42:39,640 --> 00:42:43,280
Speaker 1: quarter of the speed of light. That's how fastest thing spenning.

761
00:42:43,280 --> 00:42:45,640
Speaker 1: I won't tell you the name because it's a ridiculous

762
00:42:45,719 --> 00:42:48,920
Speaker 1: series of letters and numbers, but it's spinning at seven

763
00:42:49,040 --> 00:42:53,360
Speaker 1: hundred and sixteen hurts. That means every second, this entire

764
00:42:53,719 --> 00:42:58,120
Speaker 1: mountain sized blob of nuclear matter spins seven hundred times

765
00:42:58,200 --> 00:43:01,080
Speaker 1: around and it's eighteen thousand years from Earth in the

766
00:43:01,120 --> 00:43:05,400
Speaker 1: constellation Sagittarius and is sending us pulses very very regularly.

767
00:43:05,760 --> 00:43:08,279
Speaker 1: The other amazing thing about these pulsars is that they

768
00:43:08,360 --> 00:43:13,120
Speaker 1: are precisely timed. It's not just like roughly seven sixteen hurts,

769
00:43:13,200 --> 00:43:17,120
Speaker 1: it's like exactly and every second it's the same. These

770
00:43:17,200 --> 00:43:20,319
Speaker 1: things do not change. It's astounding when you see something

771
00:43:20,360 --> 00:43:23,040
Speaker 1: in nature that is so regular. These things have the

772
00:43:23,080 --> 00:43:27,120
Speaker 1: regularity the consistency that rivals that of atomic clocks. You

773
00:43:27,160 --> 00:43:29,040
Speaker 1: can use them as a probe of the rest of

774
00:43:29,080 --> 00:43:32,560
Speaker 1: the universe because they send out these very very regular pulses.

775
00:43:33,040 --> 00:43:35,600
Speaker 1: For example, a pulsar was actually the first way that

776
00:43:35,640 --> 00:43:39,880
Speaker 1: we had evidence of a planet around another star. Because

777
00:43:39,880 --> 00:43:42,160
Speaker 1: when a pulsar has a planet around it, that planet

778
00:43:42,280 --> 00:43:44,920
Speaker 1: is tugging on it gravitationally as it orbits, and it

779
00:43:45,000 --> 00:43:47,960
Speaker 1: means the pulsar moves towards us sometimes and away from

780
00:43:48,040 --> 00:43:51,279
Speaker 1: us other times, and this velocity changes the frequency of

781
00:43:51,320 --> 00:43:54,080
Speaker 1: the pulse are by a very small amount. Because the

782
00:43:54,160 --> 00:43:57,759
Speaker 1: pulsars are so precise and so accurate, we can detect that.

783
00:43:57,920 --> 00:44:00,040
Speaker 1: And if it's a regular shift in the free and

784
00:44:00,120 --> 00:44:02,640
Speaker 1: see the pulsar, you can deduce the presence of a

785
00:44:02,760 --> 00:44:05,680
Speaker 1: planet around the pulsar. How do you have a planet

786
00:44:05,719 --> 00:44:09,080
Speaker 1: around a pulsar? It's crazy, right, because a pulsar comes

787
00:44:09,120 --> 00:44:12,400
Speaker 1: from when the Sun was destroyed, So probably some chunk

788
00:44:12,520 --> 00:44:15,960
Speaker 1: of that nebula has now reformed, some planet which is

789
00:44:16,040 --> 00:44:20,239
Speaker 1: orbiting the pulsar, or some planet happened to amazingly survive

790
00:44:20,719 --> 00:44:23,800
Speaker 1: of the supernova explosion that created the pulsar. And you

791
00:44:23,880 --> 00:44:27,279
Speaker 1: can also use them to navigate around the galaxy. Because

792
00:44:27,360 --> 00:44:30,000
Speaker 1: every pulsar is different, each one has like its own

793
00:44:30,239 --> 00:44:33,800
Speaker 1: unique fingerprint. You can tell which one you are listening to,

794
00:44:34,120 --> 00:44:36,920
Speaker 1: and you can also tell where you are in its cycle.

795
00:44:37,040 --> 00:44:39,360
Speaker 1: Is that pointing towards me or away from me? And

796
00:44:39,400 --> 00:44:41,440
Speaker 1: if you look at multiple of these things, you can

797
00:44:41,480 --> 00:44:44,880
Speaker 1: tell like how many cycles you are away from multiple pulsars.

798
00:44:45,000 --> 00:44:48,280
Speaker 1: Lets you triangulate exactly where you are in the galaxy.

799
00:44:48,560 --> 00:44:51,600
Speaker 1: But a whole fund podcast episode about navigating deep space

800
00:44:51,760 --> 00:44:55,200
Speaker 1: using pulsars, and people have crazy plans for how to

801
00:44:55,440 --> 00:44:58,000
Speaker 1: use pulsars. For example, they want to use them as

802
00:44:58,080 --> 00:45:02,120
Speaker 1: gravitational wave detector. Remember that we have seen ripples in

803
00:45:02,200 --> 00:45:05,880
Speaker 1: the fabric of space by seeing how these gravitational waves

804
00:45:06,239 --> 00:45:10,200
Speaker 1: stretch and shrink the distances here on Earth. Well, there

805
00:45:10,280 --> 00:45:12,440
Speaker 1: might be really massive ones that we can measure their

806
00:45:12,520 --> 00:45:15,920
Speaker 1: stretching and shrinking the entire galaxy, and those would affect

807
00:45:16,000 --> 00:45:19,600
Speaker 1: the pulses from these pulsars. And so a bunch of

808
00:45:19,719 --> 00:45:23,000
Speaker 1: really precise clocks sending us dings from all around the

809
00:45:23,080 --> 00:45:27,239
Speaker 1: galaxy can be used to detect gravitational waves. So there's

810
00:45:27,239 --> 00:45:29,759
Speaker 1: a bright future for the signs of pulsars, as well

811
00:45:29,800 --> 00:45:32,880
Speaker 1: as a fascinating story that tells us exactly how they

812
00:45:32,920 --> 00:45:35,200
Speaker 1: were discovered. So thanks for coming along with me on

813
00:45:35,320 --> 00:45:39,480
Speaker 1: this ride of historical exploration to understand how we actually

814
00:45:39,520 --> 00:45:42,800
Speaker 1: make these breakthroughs, how people actually win Nobel prizes or

815
00:45:43,000 --> 00:45:45,279
Speaker 1: are sometimes cut out of it by their advisor, but

816
00:45:45,360 --> 00:45:49,759
Speaker 1: how scientific knowledge is very slowly, very painstakingly, but very

817
00:45:49,840 --> 00:45:53,520
Speaker 1: excitingly accumulated. Thanks for joining us tune in next time.

818
00:46:01,400 --> 00:46:04,200
Speaker 1: Thanks for listening, and remember that Daniel and Jorge Explain

819
00:46:04,280 --> 00:46:07,120
Speaker 1: the Universe is a production of I Heart Radio. For

820
00:46:07,280 --> 00:46:10,200
Speaker 1: more podcast for my heart Radio, visit the I heart

821
00:46:10,320 --> 00:46:13,879
Speaker 1: Radio app, Apple Podcasts, or wherever you listen to your

822
00:46:13,960 --> 00:46:20,440
Speaker 1: favorite shows. Yeah.