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Speaker 1: Hey, Kelly, how are things going on the science farm?

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Speaker 2: You know, they're going pretty well, but we have some

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Speaker 2: old pipes and they've been sailing and so, you know,

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Speaker 2: renovating the bathroom in the kitchen. We're pretty low on

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Speaker 2: why to do list, but suddenly they went to the

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Speaker 2: top and so there's been lots of renovating projects happening.

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Speaker 1: Ooh, does that mean lots of opportunities to show your

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Speaker 1: kids how to use power tools? Circular saws and arc

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Speaker 1: welders and all that good stuff.

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Speaker 2: Uh, there's lots of opportunities for me to play with

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Speaker 2: power tools, many different kinds of saws. No arc welders yet,

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Speaker 2: but generally the kids are not playing with the power.

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Speaker 1: Tools, not until they hear this episode and then they

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Speaker 1: start asking for their turn.

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Speaker 2: This is why my kids don't get to listen to

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Speaker 2: your podcast.

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Speaker 1: Man, how can you consider yourself a good parent if

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Speaker 1: you don't share this podcast with them.

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Speaker 2: I'm pretty sure that the number one rule of parenting

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Speaker 2: is keep the kids alive, and I'm pretty good at that,

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Speaker 2: and that just seem to be tied to them not

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Speaker 2: listening to your podcast.

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Speaker 1: Fair point. Hi, I'm Daniel, I'm a particle physicist and

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Speaker 1: a professor at UC Irvine, and I want everybody's kids

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Speaker 1: to stay happy and healthy.

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Speaker 2: I'm Kelly Wieder Smith. I'm a parasitologist. I'm adjunct at

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Speaker 2: Rice University, and I also want kids to stay happy

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Speaker 2: and healthy, which probably means no power tools before the

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Speaker 2: age of ten.

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Speaker 1: Ooh, you hear that Kelly's kids tenth birthday, you're getting

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Speaker 1: power tools.

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Speaker 2: Oh no, that's only a couple months away from one

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Speaker 2: of them. I meant twenty twenty.

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Speaker 1: Wow, that was pretty quick backpedaling right there. You know,

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Speaker 1: eventually they got to learn some useful skills, so arc

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Speaker 1: welding could be in their future.

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Speaker 2: You know, she's really good with the screwdriver, and I

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Speaker 2: feel like I've done my part. She could also make

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Speaker 2: a little circuit. She did that for the Talent Show

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Speaker 2: and it had little light up eyes and the mascot

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Speaker 2: of her school and it was pretty cool. I'm doing

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Speaker 2: a great job, Daniel.

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Speaker 1: You're doing a bang up job for sure, and so

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Speaker 1: welcome to the podcast. Daniel and Joor explain the universe,

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Speaker 1: in which we try to do a bang up job

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Speaker 1: of welding your brain to the universe, making those connections

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Speaker 1: between everything that's happening inside your skull and all the

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Speaker 1: physics of the universe, the black holes, the tiny particles,

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Speaker 1: the galaxies, the arc welding, everything that's going on out there.

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Speaker 1: We want you to understand it. No topic is too big,

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Speaker 1: no topic is too small, no question is too weird,

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Speaker 1: no idea is too bunkers for us to consider, because

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Speaker 1: our goal is to make sense of the whole universe.

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Speaker 1: My usual co host he can't be here today, but

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Speaker 1: I'm very happy to be joined by Kelly to talk

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Speaker 1: about today's amazing and fun topic.

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Speaker 2: I'm excited to be here. You know how, I think

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Speaker 2: you and I just had a podcasting aniversary, didn't we.

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Speaker 2: It's been like two and a half years or two,

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Speaker 2: I don't know, it's been a while. I'm excited.

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Speaker 1: Oh no, I'm embarrassed. I haven't been keeping tracks. I'm

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Speaker 1: totally unaware of our anniversary. I apologize. I should have

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Speaker 1: gotten you something.

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Speaker 2: Well, that's you got me a really interesting topic to

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Speaker 2: talk about. Oh, thank you.

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Speaker 1: Yes, that must have been my subconscious plan of what's

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Speaker 1: what it was the whole time.

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Speaker 2: Yes, the two year anniversary is the cold welding anniversary.

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Speaker 1: M Well, congratulations on two years of being on the podcast.

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Speaker 1: We love all your contributions.

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Speaker 2: Oh, I love being here.

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Speaker 1: Thanks awesome. And sometimes on the podcast we talk about

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Speaker 1: quantum mechanics. Sometimes we talk about black hole, sometimes we

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Speaker 1: talk about planetary orbits in the future of our star.

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Speaker 1: And sometimes we talk about the everyday physics and science

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Speaker 1: that is around us, stuff that makes up our lives,

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Speaker 1: how it works, and how hard it is to understand

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Speaker 1: even the everyday normal stuff in our universe.

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Speaker 2: It never gets easier.

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Speaker 1: It's sort of amazing the complexity of things that we

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Speaker 1: see around us, rocks and blueberries and ice cream, and

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Speaker 1: it's incredible that we can understand how that stuff all

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Speaker 1: comes together from the tiny little particles that are inside it.

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Speaker 1: The buzzing and tuing and frowing of all those little

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Speaker 1: bits somehow weave themselves together into this incredible experience we

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Speaker 1: have where things seem solid or liquid or gaseous, that

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Speaker 1: we know that that actually all just bubbles up from

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Speaker 1: the tiny little particles inside them.

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Speaker 2: I'm glad you're confident that we understand the world, because

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Speaker 2: as a biologist, I'm way less confident. But we'll go

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Speaker 2: with it.

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Speaker 1: You know, I was recently doing college interviews, and one

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Speaker 1: young lady told me she was really interested in biology

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Speaker 1: because she thought it was cool how you could explain

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Speaker 1: everything using the smallest bits around us, the cell. And

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Speaker 1: I was like, well, it is very cool how the

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Speaker 1: cell comes together to make complex biology. But you know

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Speaker 1: you can go further than that, right, you can dig deeper.

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Speaker 2: You leave her alone. She's on the right track.

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Speaker 1: I almost convinced her to do particle physics, but she

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Speaker 1: was like, nah, she wanted to study stuff that was

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Speaker 1: more relevant to our lives. Good for her, but there

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Speaker 1: are still lots of deep mysteries remaining about this fairly

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Speaker 1: pedestrian idea. Everything is made of particles. Those particles follow

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Speaker 1: simple rules, and how those bits bang up against each

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Speaker 1: other and stick or don't stick and repel makes up

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Speaker 1: our whole world. Why some things are shiny, why some

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Speaker 1: things are sticky. We think that those are all emergent

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Speaker 1: properties from those little particles and the rules that they follow.

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Speaker 1: But it's complicated. It's not like if you give me

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Speaker 1: the location and velocity of ten to twenty nine particles,

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Speaker 1: I can tell you exactly how they're going to behave, Oh,

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Speaker 1: this thing's going to flow or this thing's going to

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Speaker 1: conduct electricity because it's a lot of particles. It's too

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Speaker 1: many for us to understand, which is why chemistry is

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Speaker 1: still a thing, right, which is a reason, the reason,

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Speaker 1: the reason we don't just have particle physics as the

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Speaker 1: only science in the universe.

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Speaker 2: I mean, that would not be as interesting. But yeah,

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Speaker 2: I remember I took stochastic differential equations in college, and

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Speaker 2: I was just like, how do we know anything about

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Speaker 2: the universe? Ever, this is also complicated, and.

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Speaker 1: It is incredible because the universe seems chaotic. All those

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Speaker 1: tiny little particles are so dependent on other tiny little particles.

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Speaker 1: It's incredible that anything emerges. But one of the great

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Speaker 1: philosophical mysteries of science is that simple stuff does emerge.

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Speaker 1: Balls seem to follow simple trajectories, even if we can't

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Speaker 1: understand the tiny particles inside them. You can make chicken

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Speaker 1: soup without understanding quantum gravity. The universe is understandable at

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Speaker 1: all these different layers, which means there are fascinating questions

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Speaker 1: and interesting mysteries at every level of science. You know,

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Speaker 1: studying galaxies, studying people, studying cells, studying funguses, and studying

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Speaker 1: the tiny little particles questions to be asked at every level.

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Speaker 2: Not sure we'll ever understand people, but well we'll do

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Speaker 2: our best and keep.

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Speaker 1: And forward exactly. And so one of the topics we

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Speaker 1: love thinking about is how materials work. Why protons and

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Speaker 1: electrons come together to make one thing conduct electricity and

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Speaker 1: something else be transparent and something else be opaque. How

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Speaker 1: does that all emerge from the tiny little particles that

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Speaker 1: are inside them? And there's so many different aspects of

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Speaker 1: these materials we can explore, like how you stick them

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Speaker 1: together to build stuff? How does the Eiffel Tower come

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Speaker 1: together from all those individual bits of steel?

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Speaker 2: Gorilla glue?

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Speaker 1: No, wow, you just invented an entire country over there.

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Speaker 2: I mean, it's a really good glue. You can get

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Speaker 2: it in a can and spray it.

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Speaker 1: Are you saying if they were going to build the

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Speaker 1: Eiffel Tower today, they would use guerrilla glue instead of welding.

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Speaker 2: Probably, I don't know. You'll have to tell us about welding.

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Speaker 2: Then I'll make my decision at the end.

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Speaker 1: Well, today in the podcast, we are going to talk

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Speaker 1: about welding, how it works, how you can stick stuff together,

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Speaker 1: and how you can possibly do it without even heating

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Speaker 1: things up in a way that could be helpful for

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Speaker 1: space industry and could be safe for even Kelly's children.

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Speaker 2: Oh all right, you've got my attention. Maybe my oldest

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Speaker 2: can listen to the you know, second part of this discussion.

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Speaker 1: So today in the podcast, we'll be asking the question

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Speaker 1: what is cold welding? So this is a topic a

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Speaker 1: bunch of listeners wrote in to ask me about what

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Speaker 1: is the physics or the chemistry or just the science

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Speaker 1: of cold welding. How could it be possible to stick

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Speaker 1: stuff together without melting it down first, and could this

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Speaker 1: potentially be a way to build things in space?

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Speaker 2: So, you know, when you proposed the topic of cold

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Speaker 2: welding to me, I could not remember a time when

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Speaker 2: I had heard this phrase, And so my first thought

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Speaker 2: was was it like sticking like pieces of gum together?

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Speaker 2: And then I'm like, no, welding, welding specifically refers to metal, right,

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Speaker 2: It's like putting two pieces of met together, is that right?

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Speaker 1: Yeah?

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Speaker 2: Yeah, yeah, And so then I was like, I don't know,

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Speaker 2: but but I hear it has to do with space,

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Speaker 2: So I'm gonna have to I'm gonna have to go

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Speaker 2: with that. So let's see if your listeners are more

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Speaker 2: clued into the world of welding than I am. I

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Speaker 2: bet they are, so.

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Speaker 1: Thanks very much to everybody who answers these questions for

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Speaker 1: the podcast. If you would like to contribute your uninformed

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Speaker 1: speculation for the episode, please don't be shy. Write me

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Speaker 1: to questions at Danielandjorge dot com. Everybody's welcome, So think

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Speaker 1: about it for a moment before you hear these answers.

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Speaker 1: What do you think cold welding is and how does

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Speaker 1: it work? Here's what listeners had to say.

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Speaker 3: Well, cold welding can't work by heating up two metal

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Speaker 3: sources and melting them together, but it could create a

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Speaker 3: chemical reaction that causes them to melt together. So my

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Speaker 3: guess is it's not actually fire, but it's some sort

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Speaker 3: of chemical.

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Speaker 4: Maybe it is using a chemical reaction to fuse two

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Speaker 4: things together to rearrange them molecules. It reminds me of

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Speaker 4: the old farmers in Vermont would attach wrought iron gate

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Speaker 4: latches to granite posts by boring a hole in the

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Speaker 4: granite and sticking the gate latch in there, and then

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Speaker 4: pouring some sort of a powder that would create a

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Speaker 4: reaction and fuse the two together. I've tried to cut

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Speaker 4: them out many many, many years later, and it's impossible.

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Speaker 4: It's sort of just one thing.

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Speaker 2: Well, those were two great answers, And to be honest,

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Speaker 2: I hadn't heard about farmers attaching iron latches using a

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Speaker 2: powder to connect it to granite. Like that's awesome. I've

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Speaker 2: got to find an excuse for how to do that

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Speaker 2: on the farm, even though right now I don't think

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Speaker 2: I need to.

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Speaker 1: I think that sounds like farm magic, you know. I

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Speaker 1: think he'd run into some magicians and they have some

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Speaker 1: like spells and powders, and they're able to like fuse

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Speaker 1: things together. I think we need to dig into this.

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Speaker 1: This could be like a whole revolution in science.

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Speaker 2: So you hadn't heard of that before either.

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Speaker 1: Vermont farmer magic. Noila had not heard of that before.

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Speaker 2: I can imagine it being pretty obscure Vermont farmer magic.

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Speaker 2: But that's not that far away from the Salem witches.

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Speaker 1: Those farmers. You gotta be careful. You gotta be careful

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Speaker 1: using your powers out there where everybody can see you. Yeah,

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Speaker 1: but this doesn't seem to be something a lot of

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Speaker 1: people have understood. And frankly, I was a little surprised,

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Speaker 1: Kelly that you didn't come across it in all of

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Speaker 1: your deep, deep research about space settlements.

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Speaker 2: You know, I have literally thousands of pages of notes,

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Speaker 2: and my mind retains one percent of what I write down,

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Speaker 2: because I figure, why memorize it if I could just

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Speaker 2: you know, control what it control f for my search

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Speaker 2: term and then see what I wrote down in the past.

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Speaker 2: So I bet I read about cold welding at some point,

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Speaker 2: but it did not stay in my internal hard drive.

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Speaker 1: Well maybe it turns out it won't be crucial for

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Speaker 1: a space settlement, after all, we'll find out.

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Speaker 2: So I asked a silly I won't say stupid, a

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Speaker 2: silly question at the beginning. You know, could it be

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Speaker 2: like sticking two pieces of gum together? And you told

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Speaker 2: us no, it requires metal. What else are the very

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Speaker 2: very basic facts of welding.

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Speaker 1: Yeah, so before we talk about specialized cold welding, let's

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Speaker 1: just talk about normal vanilla hot welding. I guess, and

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Speaker 1: this is basically sticking two pieces of metal together. You

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Speaker 1: want to build the Eiffel Tower, you want to build

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Speaker 1: a bicycle, you want to build a tank, you want

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Speaker 1: to build an airplane, all this kind of stuff. You

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Speaker 1: got to use welding. Welding is basically the way that

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Speaker 1: we corillatly stuff together in the modern world.

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Speaker 2: So I'm doing a bathroom renovation and luckily when I

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Speaker 2: opened up the wall, there were no copper pipes, because

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Speaker 2: then I was gonna have to solder, and I don't

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Speaker 2: know how to solder, but I would have learned. Is

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Speaker 2: soldering welding because it's like that little silvery thing that

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Speaker 2: you unroll and you heat up and you put on

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Speaker 2: the copper. That's metal too, right, So does that count?

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Speaker 1: Yes, so that does not count as welding. Soldering and

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Speaker 1: welding are two different things. So welding is when you

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Speaker 1: melt two pieces of metal, so the metals themselves join

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Speaker 1: become like one piece. So you got two objects you

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Speaker 1: want to stick them together. You actually melt the edges

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Speaker 1: of both of them. Soldering is different soldering. You have

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Speaker 1: a lower temperature filler, something which melts at a much

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Speaker 1: lower temperature that basically acts as glue and bonds to

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Speaker 1: the two surfaces. But you don't actually melt the two

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Speaker 1: things you're sticking together. So you got two pipes you

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Speaker 1: want to stick together, you can solder them together. By

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Speaker 1: melting some filler material which sticks them together, or you

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Speaker 1: can actually weld them by melting the two pipes and

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Speaker 1: sticking them together when they're liquid, so when they cool,

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Speaker 1: you get those chemical bonds between them.

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Speaker 2: But soldering is still cool because you get you used

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Speaker 2: a bload. I was kind of torn when I opened

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Speaker 2: up the walls and there was pets. Part of me

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Speaker 2: wanted to solder, part of me did, But anyway, okay,

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Speaker 2: I'm getting a soft track.

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Speaker 1: And soldering somebody. You can do an electrical laborate. You

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Speaker 1: have that special solder material which you touch to the

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Speaker 1: tip of the soldering iron. It just like instantly liquifies, right,

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Speaker 1: super cool stuff, and that stuff you use because it

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Speaker 1: liquifies very very easily, and then it cools very quickly

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Speaker 1: and becomes solid again. So that's soldering. But welding is different, right.

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Speaker 1: Welding is when you really want to join these two

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Speaker 1: materials and you do it by some combination usually of

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Speaker 1: heat and pressure.

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Speaker 2: Okay, and I'm guessing that we've been welding. It's got

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Speaker 2: to be after we get access to fire. How much

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Speaker 2: after we get access to fire before we're welding.

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Speaker 1: Yeah, welding technically is something we've been doing for thousands

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Speaker 1: of years. Essentially, blacksmiths invented welding. They notice you got

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Speaker 1: two pieces of metal, you heat them up and pound

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Speaker 1: them hard enough. They will join a lot of the

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Speaker 1: stuff that's been connected together to make basic swords and

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Speaker 1: tools for farms and all this stuff that blacksmiths have

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Speaker 1: been making for thousands of years. They called that forge welding. Basically,

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Speaker 1: heat it up and hammer it hard and you will

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Speaker 1: get that fusion, that connection between the two materials that

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Speaker 1: tells you that they are now one.

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Speaker 2: Okay, So they're using like a furnace, Is that the

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Speaker 2: most typical way or a blowtorch? Is that the most

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Speaker 2: typical way to get the heat that you need to

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Speaker 2: combine two metals.

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Speaker 1: Yeah, exactly. And when my dad retired from Los Almo's

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Speaker 1: National Labs, he actually took up blacksmithing as a hobby.

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Speaker 1: I was pretty sure he was like preparing for the

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Speaker 1: end times. He thought, like, what would be a useful

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Speaker 1: skill to have if civilization collapsed, and he decided blacksmithing

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Speaker 1: would be useful, And so he got a little furnace

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Speaker 1: and he would go to the dump and like pick

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Speaker 1: up scrap metal, you know, like truck suspensions and all

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Speaker 1: sorts of stuff, and he would melt it down and

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Speaker 1: hammer it into shapes. And he made all sorts of

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Speaker 1: stuff from like towel hooks to his own spears and

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Speaker 1: stuff like that.

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Speaker 2: Whoa, that's awesome.

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Speaker 1: It was pretty cool until half the town burnt down

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Speaker 1: in a forest fire, which is a real tragedy. And

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Speaker 1: then the neighbors were a lot less keen on him

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Speaker 1: having like a thousands of degrees furnace in his garage

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Speaker 1: spewing up sparks into the dry woods. So he got

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Speaker 1: shut down. Yeah, reasonable, reasonable, yep.

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Speaker 2: But said, hey, do you know what turneski?

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Speaker 1: I don't. Who's that?

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Speaker 2: I think he's the current blacksmith that loaves Alabos and

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Speaker 2: he's a friend of mine. Oh, right, back and off, okay, okay,

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Speaker 2: So I was trying to get you to talk about electricity.

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Speaker 1: Yeah, but blacksmithing is an ancient form of welding, right,

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Speaker 1: You heat it up, you squish it together, and what's

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Speaker 1: happening there is that the metals on one side and

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Speaker 1: the metals on the other side are bonding together, and

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Speaker 1: so there's really no distinction there. And that makes a

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Speaker 1: very very strong connection. Right. But in the late nineteenth

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Speaker 1: century we invented arc welding. We had electricity now, and

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Speaker 1: see we could more efficiently deliver energy than just like

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Speaker 1: sticking the whole thing in an oven, which also isn't

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Speaker 1: possible if you don't have a big enough oven. You

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Speaker 1: want to weld together two I beams, you don't want

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Speaker 1: to have to stick the whole thing in the oven

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Speaker 1: and then hammer them together. You want to only heat

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Speaker 1: at the spot that between them that's touching.

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Speaker 2: So what is more dangerous a giant furnace operating at

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Speaker 2: intense heat or electrifying metals and working with fads. Kid

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Speaker 2: one is not allowed to listen to the episode up

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Speaker 2: to this point yet, let's see where we get to.

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Speaker 1: But our welding is actually really cool because it basically

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Speaker 1: makes a circuit. You're running electricity through the metals, and

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Speaker 1: because the metals are not perfect conductors, there's some resistance

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Speaker 1: to them, and resistance means heat resistance. You're turning electrical

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Speaker 1: energy into thermal energy. Like the way a light bulb

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Speaker 1: works is you're running electrical current through something which is

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Speaker 1: a resistorance. It's gonna heat up and then it's going

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Speaker 1: to glow. So the reason the metals get hot is

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Speaker 1: the same reason that a light bulb glows.

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Speaker 2: Ah, And so we just don't let it get out

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Speaker 2: of control because you don't want your light bulbs burning

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Speaker 2: or melting.

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Speaker 1: That's right. And so in arc welding, what you're doing

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Speaker 1: is creating a circuit, and then you're passing that electricity

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Speaker 1: from a stick which arcs onto the spot that you're

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Speaker 1: trying to weld, passes energy through that and then completes

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Speaker 1: the circuit. And so you just power that electricity back

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Speaker 1: and forth. You can be DC, you can be acy,

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Speaker 1: all sorts of varieties of it. It was meant that

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Speaker 1: in the eighteen hundreds when people were learning about the

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Speaker 1: power of electricity.

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Speaker 2: You know, you've got me wondering now, fun tangent. So

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Speaker 2: the first the first space walk ever conducted by a

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Speaker 2: woman was a sptlanasub Atskaya, and she welded in the

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Speaker 2: vacuum of space for the first time. So do you

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Speaker 2: think that she welded with heat or electricity?

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Speaker 1: I suspect that was an arc welding, right, because the

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Speaker 1: heat generation from like a blowtorch might require combustion with

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Speaker 1: the atmosphere respect that was probably arc welding.

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Speaker 2: Yeah, oh I should have known that. As soon as

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Speaker 2: you started saying it, I was like, oh, of course.

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Speaker 2: But anyway, all right, so fun, Yeah, there you go.

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Speaker 1: But hold on, that sounds super dangerous. You have this

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Speaker 1: like arc welding in space. I mean that could easily

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Speaker 1: rupture a suit or cause some damage. So that seems

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Speaker 1: crazy to me.

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Speaker 2: Well, you know what's infuriating she is this like hypercompetent,

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Speaker 2: incredible cosmonaut. And there's this movie called Solute seven that

377
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Speaker 2: came out in Russia and it's sort of like Solute

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Speaker 2: seven is almost their equivalent to our Apollo thirteen. So

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Speaker 2: Solute seven like they had a problem I think it

380
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Speaker 2: was with the solar panels and the power ran down,

381
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Speaker 2: so they had to send somebody up there to try

382
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Speaker 2: to fix it and get it back online. But at

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Speaker 2: the beginning of the movie they create this scene where

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Speaker 2: Setlanasovitskaya is welding in space, which happens, but she gets

385
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Speaker 2: a welding burr in her glove and she's starting to

386
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Speaker 2: lose pressure and her male colleague needs to pull her

387
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Speaker 2: back into the station because she just like I don't know.

388
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Speaker 2: It's like losing her composure. And that didn't happen. She

389
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Speaker 2: did a great job of welding. She didn't get a

390
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Speaker 2: burr in her glove. She didn't need to be saved

391
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Speaker 2: by a man. But that's how the movie starts, and

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Speaker 2: that made me very frustrated. Tangent done. Oh and the

393
00:20:14,440 --> 00:20:17,920
Speaker 2: rest No, no, almost done, Tangent almost done. The other

394
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Speaker 2: big lie in the movie is that they need to

395
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Speaker 2: get up there to get the station started again because

396
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Speaker 2: the shuttle, the Americans are going to set off the

397
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Speaker 2: Shuttle and they want our technology, so they're going to

398
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Speaker 2: put the Salute seven space station in the shuttle's cargo

399
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Speaker 2: bay and take it back to Earth to steal our technology,

400
00:20:37,520 --> 00:20:42,439
Speaker 2: which it wouldn't fit. That didn't happen, but that's like

401
00:20:42,480 --> 00:20:44,280
Speaker 2: a huge and at the very end you've got the

402
00:20:44,320 --> 00:20:47,320
Speaker 2: Space Shuttle driving past Salute and the Space Shuttle people

403
00:20:47,320 --> 00:20:50,960
Speaker 2: who are driving Salute the Solute cosmonauts for doing such

404
00:20:50,960 --> 00:20:52,760
Speaker 2: a good job of getting it fixed before they could

405
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Speaker 2: go there to steal it. And it was like what anyway,

406
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Speaker 2: a classic film, Like all.

407
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Speaker 1: The research you did for your space settlement book may

408
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Speaker 1: have ruined you for science fiction Kelly.

409
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Speaker 2: Ah, yeah, yeah, that's probably true.

410
00:21:09,320 --> 00:21:11,360
Speaker 1: That's the downside of knowing a bunch of stuff.

411
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Speaker 2: Better not to know.

412
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Speaker 1: So in the eighteen hundreds we developed this new technique

413
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Speaker 1: like basically the first advance since blacksmithing for thousands of

414
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Speaker 1: years in how to join metals. And this got really

415
00:21:24,920 --> 00:21:27,879
Speaker 1: fast forwarded in the World Wars in the early nineteen

416
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Speaker 1: hundreds because people wanted to make lots and lots of

417
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Speaker 1: tanks and airplanes and all sorts of stuff, and arc

418
00:21:34,000 --> 00:21:36,679
Speaker 1: welding can be a little bit painful, it's kind of slow,

419
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Speaker 1: and it can be inefficient, and so they developed lots

420
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Speaker 1: more techniques to do this much more quickly, to do

421
00:21:42,359 --> 00:21:46,320
Speaker 1: it much more efficiently. So fast welding really was born

422
00:21:46,480 --> 00:21:49,359
Speaker 1: in the first part of last century because of the

423
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Speaker 1: World Wars, humans wanted to kill each other more efficiently,

424
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Speaker 1: so they had to be quick at building those killing machines.

425
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Speaker 2: So depressing. Same goes for rockets, right, that's the rockets

426
00:22:00,160 --> 00:22:02,320
Speaker 2: took us to the Moon. We're used to drop bombs

427
00:22:02,320 --> 00:22:06,840
Speaker 2: on London without great aim, I'd say, But anyway, Yeah, it's.

428
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Speaker 1: A conflict I feel deeply internally. I mean a lot

429
00:22:09,160 --> 00:22:12,600
Speaker 1: of advances in physics come from wanting to build weapons

430
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Speaker 1: of mass destruction, and so that's you know, also where

431
00:22:16,000 --> 00:22:17,960
Speaker 1: a lot of fund incomes from. But it does, in

432
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Speaker 1: the end reveal a lot about the nature of the universe.

433
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Speaker 1: So it's a tough situation, yep. But it turns out

434
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Speaker 1: that you could apply a lot of these welding techniques

435
00:22:26,040 --> 00:22:30,640
Speaker 1: not just to metals. You can also weld things like glass. Right,

436
00:22:30,640 --> 00:22:32,560
Speaker 1: you can take two pieces of glass and you can

437
00:22:32,600 --> 00:22:35,200
Speaker 1: have a glass rod, and you can use a blowtorch

438
00:22:35,280 --> 00:22:37,679
Speaker 1: to melt the glass and stick them together. And so

439
00:22:37,680 --> 00:22:40,360
Speaker 1: you can weld pieces of glass together. You can even

440
00:22:40,440 --> 00:22:43,879
Speaker 1: weld glass to ceramic or to steal all sorts of stuff.

441
00:22:44,200 --> 00:22:46,520
Speaker 1: So welding is not just something you have to do

442
00:22:46,600 --> 00:22:47,320
Speaker 1: with metals.

443
00:22:47,520 --> 00:22:50,040
Speaker 2: I didn't realize that. I guess I did think welding

444
00:22:50,119 --> 00:22:51,000
Speaker 2: was metal specific.

445
00:22:51,359 --> 00:22:55,120
Speaker 1: Yeah, it's basically just joining stuff together by melting them.

446
00:22:55,560 --> 00:22:57,480
Speaker 1: And it makes a lot of sense because you melt

447
00:22:57,520 --> 00:22:59,720
Speaker 1: it together and that the atoms are all jiggling and

448
00:22:59,720 --> 00:23:02,080
Speaker 1: they can and jiggle together and when they cool, it's

449
00:23:02,119 --> 00:23:05,560
Speaker 1: like they're one again. What sort of mysterious is doing

450
00:23:05,600 --> 00:23:10,200
Speaker 1: this without heat? And so cold welding is a much stranger,

451
00:23:10,359 --> 00:23:14,120
Speaker 1: much more interesting and maybe potentially useful in space kind

452
00:23:14,160 --> 00:23:15,240
Speaker 1: of process.

453
00:23:15,080 --> 00:23:17,840
Speaker 2: And we're going to learn more about it after the break.

454
00:23:30,400 --> 00:23:35,640
Speaker 2: All right, So, hot welding uses heat to combine metal, glass, plastic,

455
00:23:35,640 --> 00:23:39,880
Speaker 2: and steal. But you have told me that we can

456
00:23:39,920 --> 00:23:42,640
Speaker 2: do it without heat, and so maybe my daughter can

457
00:23:42,680 --> 00:23:46,919
Speaker 2: listen to this part of the episode. So how do

458
00:23:46,960 --> 00:23:48,920
Speaker 2: we do that? Do we just bang them together really

459
00:23:48,960 --> 00:23:49,960
Speaker 2: hard and hope they stick.

460
00:23:52,080 --> 00:23:54,719
Speaker 1: That's the long and short of it. Yes, essentially you

461
00:23:54,760 --> 00:23:58,520
Speaker 1: can do cold welding if you have pressure and if

462
00:23:58,560 --> 00:24:01,920
Speaker 1: the materials are very, very very clean. Think about what's

463
00:24:01,920 --> 00:24:05,040
Speaker 1: happening inside of metal. Metal is essentially a crystal. You

464
00:24:05,119 --> 00:24:08,840
Speaker 1: have all of these atoms of iron or whatever, and

465
00:24:08,880 --> 00:24:11,000
Speaker 1: they're lining up in a crystal, and the reason they're

466
00:24:11,000 --> 00:24:13,399
Speaker 1: so strong is all those bonds are holding them together.

467
00:24:13,960 --> 00:24:15,600
Speaker 1: How do you make a bigger crystal? Well, you could

468
00:24:15,600 --> 00:24:18,560
Speaker 1: like rejigger all the atoms and make them liquid again

469
00:24:19,040 --> 00:24:21,320
Speaker 1: and then stick them together so they cool back down

470
00:24:21,320 --> 00:24:23,280
Speaker 1: to make a crystal. But what if you just have

471
00:24:23,480 --> 00:24:25,679
Speaker 1: like half of a crystal here and half of a

472
00:24:25,680 --> 00:24:29,120
Speaker 1: crystal there, and you just like stick them together so

473
00:24:29,160 --> 00:24:32,359
Speaker 1: that the two bits of crystal like link together, sort

474
00:24:32,359 --> 00:24:34,560
Speaker 1: of like sticking two puzzle pieces together.

475
00:24:34,640 --> 00:24:34,720
Speaker 3: Right.

476
00:24:34,760 --> 00:24:37,639
Speaker 1: You don't have to melt them down to liquid cardboard

477
00:24:37,720 --> 00:24:39,720
Speaker 1: to make to stick them together. You just sort of

478
00:24:40,000 --> 00:24:42,960
Speaker 1: fit the nibs into the holes and they click together

479
00:24:43,119 --> 00:24:46,920
Speaker 1: into one big picture. Okay, So that's the sort of

480
00:24:47,040 --> 00:24:49,960
Speaker 1: idea behind cold welding. Like, if you have a material

481
00:24:50,000 --> 00:24:52,640
Speaker 1: that's very regular and you have two pieces of it,

482
00:24:52,800 --> 00:24:55,160
Speaker 1: if you just get them together close enough and apply

483
00:24:55,200 --> 00:24:57,440
Speaker 1: a little bit of pressure, they will all of a

484
00:24:57,480 --> 00:25:00,600
Speaker 1: sudden act like they were always one thing. They will

485
00:25:00,640 --> 00:25:02,240
Speaker 1: just sort of like stick together.

486
00:25:02,560 --> 00:25:04,960
Speaker 2: All right. So I'm having a little trouble wrapping my

487
00:25:05,000 --> 00:25:07,480
Speaker 2: head around it. So I'm imagining like, all right, so

488
00:25:07,520 --> 00:25:10,840
Speaker 2: you put two pieces of metal together, and very very

489
00:25:10,960 --> 00:25:15,240
Speaker 2: very slowly they start what like acting like liquid and

490
00:25:15,520 --> 00:25:20,560
Speaker 2: sort of mixing together or yeah, why so why does that?

491
00:25:20,680 --> 00:25:21,520
Speaker 2: Why does that happen?

492
00:25:21,840 --> 00:25:24,200
Speaker 1: It's not very very slow. The whole thing can happen

493
00:25:24,359 --> 00:25:28,679
Speaker 1: in seconds or less, and there's no liquid involved. This

494
00:25:28,800 --> 00:25:33,280
Speaker 1: is just two pieces of metal clicking together. I read

495
00:25:33,280 --> 00:25:36,600
Speaker 1: this fun quote by Richard Feinman. He says, quote, the

496
00:25:36,680 --> 00:25:39,800
Speaker 1: reason for this unexpected behavior is that when the atoms

497
00:25:39,880 --> 00:25:43,119
Speaker 1: in contact are all of the same kind. There's no

498
00:25:43,200 --> 00:25:45,600
Speaker 1: way for the atoms to know they are in different

499
00:25:45,600 --> 00:25:48,920
Speaker 1: pieces of copper. Essentially, you just have like a bunch

500
00:25:48,920 --> 00:25:50,399
Speaker 1: of copper here and a bunch of copper there. You

501
00:25:50,400 --> 00:25:53,400
Speaker 1: bring them close together, they will stick together. They do

502
00:25:53,600 --> 00:25:56,040
Speaker 1: like to bond to each other. Think about what happens

503
00:25:56,040 --> 00:25:58,760
Speaker 1: between two atoms of copper. There are electrons that are

504
00:25:58,760 --> 00:26:01,800
Speaker 1: like flowing between them, bonding them together. That's what the

505
00:26:01,840 --> 00:26:04,840
Speaker 1: bond is, right, The actual nuclei are and stuck together.

506
00:26:04,800 --> 00:26:07,639
Speaker 1: It's thee electrons between them. And so if you have

507
00:26:07,720 --> 00:26:10,399
Speaker 1: two atoms you bring them near each other, they will bond.

508
00:26:10,480 --> 00:26:12,960
Speaker 1: They don't have to become a liquid in order to

509
00:26:13,000 --> 00:26:13,679
Speaker 1: bond together.

510
00:26:14,240 --> 00:26:18,560
Speaker 2: So why do metals do this? And like the I've

511
00:26:18,600 --> 00:26:20,840
Speaker 2: got a book sitting next to me with lots of pages,

512
00:26:20,920 --> 00:26:25,800
Speaker 2: but the pages are staying distinct. Why why doesn't everything

513
00:26:25,960 --> 00:26:29,440
Speaker 2: start just sort of blending together.

514
00:26:30,720 --> 00:26:33,240
Speaker 1: Exactly? Why isn't the whole world just fuse the one

515
00:26:33,359 --> 00:26:38,080
Speaker 1: lump right exactly? Yes, this is something metals can do

516
00:26:38,520 --> 00:26:42,159
Speaker 1: because the electrons in a metal are very mobile. Like

517
00:26:42,280 --> 00:26:45,679
Speaker 1: some materials, the electrons mostly stick around their own atom

518
00:26:45,880 --> 00:26:49,280
Speaker 1: or the neighboring atom. But when metals come together the

519
00:26:49,400 --> 00:26:52,720
Speaker 1: energy levels of those electrons are such that the electrons

520
00:26:52,720 --> 00:26:55,239
Speaker 1: can really flow freely through the metal. It's more like

521
00:26:55,480 --> 00:26:58,679
Speaker 1: an ocean of electrons. And this all depends on how

522
00:26:58,720 --> 00:27:01,639
Speaker 1: the energy levels translate. Like you have an individual atom,

523
00:27:02,119 --> 00:27:05,280
Speaker 1: we know that the electrons around that atom have energy levels.

524
00:27:05,640 --> 00:27:07,640
Speaker 1: Like you remember from your high school chemistry that there's

525
00:27:07,720 --> 00:27:10,439
Speaker 1: like the one p orbital and the four f orbital,

526
00:27:10,440 --> 00:27:12,400
Speaker 1: and there's all these energy levels for an electron.

527
00:27:12,520 --> 00:27:15,000
Speaker 2: We shouldn't assume I remember anything from high school chemistry,

528
00:27:15,000 --> 00:27:15,600
Speaker 2: but keep going.

529
00:27:16,000 --> 00:27:17,879
Speaker 1: I don't remember it either. I probably just remember it

530
00:27:17,920 --> 00:27:20,959
Speaker 1: because my son is taking high school chemistry, so I

531
00:27:20,960 --> 00:27:24,439
Speaker 1: have to hear about all this stuff. Anyway, Electrons around

532
00:27:24,520 --> 00:27:27,919
Speaker 1: atoms have energy levels, right, Well, what happens when you

533
00:27:28,000 --> 00:27:30,040
Speaker 1: have two atoms and now your electrons are sort of

534
00:27:30,040 --> 00:27:33,199
Speaker 1: like zigging back and forth between those two atoms. Well,

535
00:27:33,240 --> 00:27:36,760
Speaker 1: the energy levels get more complicated because you're now responding

536
00:27:37,040 --> 00:27:40,520
Speaker 1: to the positive charge of two atoms. Now add another atom,

537
00:27:40,560 --> 00:27:42,440
Speaker 1: and another atom and another atom. You get a whole

538
00:27:42,440 --> 00:27:44,919
Speaker 1: crystal lattice. And so now you get a bunch of

539
00:27:44,960 --> 00:27:49,560
Speaker 1: different energy levels for the electrons. And metals and insulators

540
00:27:49,600 --> 00:27:53,119
Speaker 1: have different kinds of energy levels there. In metals, it's

541
00:27:53,240 --> 00:27:55,840
Speaker 1: very easy for the electrons to jump up to the

542
00:27:55,920 --> 00:27:58,439
Speaker 1: higher energy levels and then move around the whole atom.

543
00:27:58,880 --> 00:28:01,879
Speaker 1: In insulators is like a big gap, then the electrons

544
00:28:01,960 --> 00:28:04,199
Speaker 1: can't easily get up there, so they're sort of like

545
00:28:04,280 --> 00:28:08,000
Speaker 1: trapped around individual atoms more So, the short answer is,

546
00:28:08,080 --> 00:28:10,080
Speaker 1: metals have a lot of electrons that are easy to

547
00:28:10,160 --> 00:28:12,359
Speaker 1: flow around, and so if you bring two pieces of

548
00:28:12,400 --> 00:28:15,040
Speaker 1: metal together, their electrons would just sort of like start

549
00:28:15,080 --> 00:28:17,800
Speaker 1: flowing back and forth, and then the copper atoms will

550
00:28:17,800 --> 00:28:20,560
Speaker 1: be like, hey, you're my neighbor. I'm your neighbor. Let's

551
00:28:20,560 --> 00:28:22,840
Speaker 1: share electrons, and boom, they're bonded.

552
00:28:23,440 --> 00:28:26,639
Speaker 2: So all right, So I've got these copper pipes m

553
00:28:27,160 --> 00:28:30,400
Speaker 2: in a different part of my house, and and if

554
00:28:30,440 --> 00:28:32,920
Speaker 2: you get this electron c and these metals can all

555
00:28:32,960 --> 00:28:38,120
Speaker 2: like come together. Why do my copper pipes retain their shape?

556
00:28:38,960 --> 00:28:42,360
Speaker 2: Why doesn't the like copper you know that's above or

557
00:28:42,440 --> 00:28:44,040
Speaker 2: that's at the top of the pipe sort of like

558
00:28:44,360 --> 00:28:46,720
Speaker 2: start moving into the copper that's at the bottom of

559
00:28:46,760 --> 00:28:48,800
Speaker 2: the pipe, and it all just sort of like becomes

560
00:28:48,800 --> 00:28:49,200
Speaker 2: a glob.

561
00:28:51,200 --> 00:28:54,800
Speaker 1: Well, copper is pretty strong, right, it's crystal structure preserve itself,

562
00:28:55,040 --> 00:28:57,560
Speaker 1: but when it comes next to another piece of that

563
00:28:57,640 --> 00:29:00,800
Speaker 1: crystal structure, then they will link together. It's just like

564
00:29:00,840 --> 00:29:04,320
Speaker 1: the puzzle pieces, right. Puzzle pieces hold themselves together into

565
00:29:04,320 --> 00:29:06,680
Speaker 1: a shape, but if you bring them nearby into something

566
00:29:06,680 --> 00:29:09,520
Speaker 1: else where where the nibs and the holes all match up,

567
00:29:09,680 --> 00:29:12,280
Speaker 1: they will click in the place. The real question is,

568
00:29:12,320 --> 00:29:15,560
Speaker 1: like you've touched copper together before, you didn't notice it,

569
00:29:15,640 --> 00:29:18,600
Speaker 1: like cold welding together. Right. It's not like every time

570
00:29:18,640 --> 00:29:22,120
Speaker 1: two copper pennies touch that they cold weld. It's not

571
00:29:22,160 --> 00:29:24,160
Speaker 1: like every time you have change in your pocket you

572
00:29:24,200 --> 00:29:26,720
Speaker 1: pull it out and it's like one single blob. Right,

573
00:29:27,000 --> 00:29:29,680
Speaker 1: That would be pretty weird. And so why doesn't this

574
00:29:29,720 --> 00:29:33,000
Speaker 1: happen all the time. The answer is that these materials

575
00:29:33,080 --> 00:29:36,200
Speaker 1: have to be really really clean. Essentially, you need like

576
00:29:36,360 --> 00:29:39,520
Speaker 1: really bare copper to touch really bare copper, or bar

577
00:29:39,600 --> 00:29:42,760
Speaker 1: iron to touch bear iron, and that doesn't happen very

578
00:29:42,800 --> 00:29:46,440
Speaker 1: often because we're in an atmosphere, and so the copper

579
00:29:46,480 --> 00:29:49,680
Speaker 1: in your pipes interacts with the atmosphere and the oxygen

580
00:29:49,720 --> 00:29:53,120
Speaker 1: in the atmosphere and forms like thin layers of oxides.

581
00:29:53,600 --> 00:29:55,360
Speaker 1: So if you take two copper pipes and you bang

582
00:29:55,360 --> 00:29:58,400
Speaker 1: them together, the copper is not actually touching. What's touching

583
00:29:58,640 --> 00:30:01,479
Speaker 1: are these thin layers of sides and greases and all

584
00:30:01,480 --> 00:30:04,080
Speaker 1: sorts of other stuff on the surface, So you're not

585
00:30:04,160 --> 00:30:06,160
Speaker 1: really getting that clean contact.

586
00:30:06,600 --> 00:30:06,760
Speaker 4: Is it?

587
00:30:07,360 --> 00:30:09,479
Speaker 2: Also like a lot of the metals that you encounter

588
00:30:09,680 --> 00:30:11,440
Speaker 2: that we encounter in our day to day lives, are

589
00:30:11,440 --> 00:30:14,719
Speaker 2: they pure metals or are they also metals that have

590
00:30:14,880 --> 00:30:16,320
Speaker 2: like other stuff mixed in.

591
00:30:16,520 --> 00:30:19,040
Speaker 1: Yeah, a lot of the stuff we interact with are alloys, right,

592
00:30:19,120 --> 00:30:21,720
Speaker 1: steel for example, there's all sorts of stuff mixed into it,

593
00:30:22,120 --> 00:30:23,840
Speaker 1: and a lot of stuff we interact with are not

594
00:30:24,000 --> 00:30:27,800
Speaker 1: pure metals. So this requires sort of a special situation.

595
00:30:27,960 --> 00:30:30,480
Speaker 1: You need pure metals and you need them to be

596
00:30:30,640 --> 00:30:34,440
Speaker 1: super duper clean, And so if you wanted to accomplish

597
00:30:34,480 --> 00:30:36,960
Speaker 1: cold welding, what you got to do is like really

598
00:30:37,080 --> 00:30:40,200
Speaker 1: carefully clean the surface. Sometimes you can actually just rub

599
00:30:40,240 --> 00:30:43,480
Speaker 1: the two surfaces together in order to scrape them clear

600
00:30:43,520 --> 00:30:46,240
Speaker 1: of these oxides, press them together, and they will make

601
00:30:46,320 --> 00:30:47,400
Speaker 1: a metallic bond.

602
00:30:47,720 --> 00:30:51,000
Speaker 2: So like if I rub my copper pipes, I know

603
00:30:51,040 --> 00:30:53,280
Speaker 2: I'm stuck on the copper pipes. I rubbed the copper

604
00:30:53,280 --> 00:30:55,400
Speaker 2: pipes together to clean them off and press them together.

605
00:30:56,400 --> 00:30:57,880
Speaker 2: Is that going to be enough or know where we

606
00:30:57,960 --> 00:31:00,400
Speaker 2: back to. Your copper pipes are probably not pure copper.

607
00:31:01,680 --> 00:31:04,080
Speaker 1: It depends on the purity of your copper. But this

608
00:31:04,160 --> 00:31:06,600
Speaker 1: is something you can actually accomplish like down here on

609
00:31:06,640 --> 00:31:10,520
Speaker 1: Earth without special materials. It was first demonstrated in the

610
00:31:10,560 --> 00:31:14,200
Speaker 1: mid seventeen hundreds by a guy in England who just

611
00:31:14,240 --> 00:31:17,200
Speaker 1: took two lead balls and he pressed them together and

612
00:31:17,200 --> 00:31:19,960
Speaker 1: twisted them and rubbed them together and the two pieces

613
00:31:19,960 --> 00:31:22,680
Speaker 1: would join. This seemed like magic at the time. It's

614
00:31:22,760 --> 00:31:25,920
Speaker 1: like without any heat, he's somehow turning two lead balls

615
00:31:25,960 --> 00:31:28,280
Speaker 1: into one single thing of lead.

616
00:31:28,760 --> 00:31:30,080
Speaker 2: Did they burn him at the state.

617
00:31:31,920 --> 00:31:36,920
Speaker 1: Him and all the Vermont farmers, Yeah, exactly. This was

618
00:31:36,960 --> 00:31:40,120
Speaker 1: in the or mid seventeen hundred, so seventeen twenty four

619
00:31:40,920 --> 00:31:44,720
Speaker 1: by a guy named Reverend Dsagular I'm not sure if

620
00:31:44,760 --> 00:31:48,280
Speaker 1: he's actually French, and it's like Disagulae, but he demonstrated

621
00:31:48,280 --> 00:31:51,200
Speaker 1: this phenomenon to the Royal Society and published the details

622
00:31:51,240 --> 00:31:54,440
Speaker 1: in a scientific journal at the time. So this is

623
00:31:54,480 --> 00:31:58,520
Speaker 1: something you can accomplish with pretty normal materials, and then

624
00:31:58,680 --> 00:32:01,840
Speaker 1: archaeologists discover the humans have actually been doing this for

625
00:32:01,960 --> 00:32:05,640
Speaker 1: thousands of years. You don't need heat in order to

626
00:32:05,680 --> 00:32:08,920
Speaker 1: accomplish welding as long as you have pressure and you

627
00:32:09,000 --> 00:32:12,760
Speaker 1: have two clean materials. So people have found like gold

628
00:32:12,840 --> 00:32:17,200
Speaker 1: boxes made by cold welding that date to like seven

629
00:32:17,280 --> 00:32:18,120
Speaker 1: hundred BC.

630
00:32:18,560 --> 00:32:21,960
Speaker 2: Okay, so this is going to be potentially another silly question.

631
00:32:22,520 --> 00:32:27,760
Speaker 2: So these boxes were gold, and so if having them

632
00:32:27,800 --> 00:32:30,760
Speaker 2: together is enough for them to weld, how do we

633
00:32:30,800 --> 00:32:33,800
Speaker 2: know that they hadn't like that this gold wasn't like

634
00:32:33,920 --> 00:32:37,240
Speaker 2: lining a wooden box and over time it cold welded

635
00:32:37,280 --> 00:32:39,680
Speaker 2: on its own, Like, how do we know that they

636
00:32:39,720 --> 00:32:40,800
Speaker 2: did it purposefully?

637
00:32:41,000 --> 00:32:41,440
Speaker 4: Oh? Yeah?

638
00:32:41,680 --> 00:32:43,400
Speaker 2: Or how do we know they didn't use hot welding.

639
00:32:44,240 --> 00:32:46,800
Speaker 1: If you do hot welding, you can see the effects

640
00:32:46,840 --> 00:32:49,719
Speaker 1: at the intersection, like you can see that it's been melted.

641
00:32:49,760 --> 00:32:52,400
Speaker 1: It changes the chemical composition a little bit, and then

642
00:32:52,440 --> 00:32:54,760
Speaker 1: there's a transition there between the heated part and the

643
00:32:54,760 --> 00:32:57,680
Speaker 1: not heated part. So cold welding does look different from

644
00:32:57,720 --> 00:33:00,360
Speaker 1: hot welding, so we can tell that this was not

645
00:33:00,480 --> 00:33:03,640
Speaker 1: hot welded gold. Obviously, people have been doing goldsmithing also

646
00:33:03,680 --> 00:33:06,800
Speaker 1: for thousands of years using heat and hammering, but these

647
00:33:06,800 --> 00:33:10,000
Speaker 1: are cold welded materials. But you're right, it could have

648
00:33:10,040 --> 00:33:13,200
Speaker 1: been accidental and probably the discovery of it was accidental.

649
00:33:13,400 --> 00:33:16,640
Speaker 1: Somebody for some reason accidentally squeezed two pieces of gold

650
00:33:16,640 --> 00:33:19,280
Speaker 1: together and discovered they had welded. And you know, I

651
00:33:19,280 --> 00:33:21,680
Speaker 1: hope that was a happy accident for whoever was doing that.

652
00:33:24,200 --> 00:33:25,280
Speaker 2: Oh, happy accident.

653
00:33:26,960 --> 00:33:29,000
Speaker 1: But it's sort of amazing that you can do this,

654
00:33:29,080 --> 00:33:31,200
Speaker 1: you know. On one hand, it seems sort of crazy,

655
00:33:31,480 --> 00:33:33,640
Speaker 1: like you stick two things together and they like talk

656
00:33:33,720 --> 00:33:37,280
Speaker 1: to each other, and they like intermingle themselves and click together.

657
00:33:37,360 --> 00:33:41,560
Speaker 1: It seems kind of impossible to get everything lined up right.

658
00:33:41,920 --> 00:33:44,440
Speaker 1: On the other hand, it seems kind of obvious because

659
00:33:44,680 --> 00:33:47,880
Speaker 1: copper is copper. Like you make copper crystal over here

660
00:33:47,920 --> 00:33:50,240
Speaker 1: and you make copper crystal over there. They're gonna have

661
00:33:50,280 --> 00:33:53,520
Speaker 1: the same atomic spacing. It's basically the same stuff. It's

662
00:33:53,640 --> 00:33:56,520
Speaker 1: ready to get clicked together. You push on it a

663
00:33:56,520 --> 00:33:59,160
Speaker 1: little bit, and those atoms are just gonna happily line

664
00:33:59,240 --> 00:34:02,120
Speaker 1: up and interact with their new neighbors. It doesn't really

665
00:34:02,160 --> 00:34:04,720
Speaker 1: matter that they used to be separate. When to push

666
00:34:04,800 --> 00:34:07,400
Speaker 1: them together, they're ready to grab onto each other.

667
00:34:07,520 --> 00:34:09,560
Speaker 2: I feel like once you explain the concept to me,

668
00:34:09,680 --> 00:34:12,640
Speaker 2: it's less surprising to me that it happens and more

669
00:34:12,680 --> 00:34:15,480
Speaker 2: surprising to me that it doesn't happen, Yes, all the time.

670
00:34:17,680 --> 00:34:20,759
Speaker 2: Are there examples of it happening when it's not when

671
00:34:20,760 --> 00:34:22,120
Speaker 2: it wasn't intended to happen.

672
00:34:22,280 --> 00:34:24,640
Speaker 1: Oh, there's lots of examples of it happening when it

673
00:34:24,680 --> 00:34:27,960
Speaker 1: wasn't intended, especially in the space program, which we'll get

674
00:34:28,000 --> 00:34:30,440
Speaker 1: into in a little bit. It's a little bit complex

675
00:34:30,480 --> 00:34:33,200
Speaker 1: to make it happen for more complex materials, like if

676
00:34:33,200 --> 00:34:36,560
Speaker 1: you imagine something that's an alloy or an ionic solid.

677
00:34:36,880 --> 00:34:39,200
Speaker 1: These things really are more complex because they have lots

678
00:34:39,200 --> 00:34:42,120
Speaker 1: of different components to them, and so getting everything lined

679
00:34:42,160 --> 00:34:45,000
Speaker 1: up is more tricky. I think it is possible in

680
00:34:45,120 --> 00:34:47,960
Speaker 1: principle to cold well things that are not like pure

681
00:34:48,000 --> 00:34:51,640
Speaker 1: copper or pure gold. It's just harder. You basically need

682
00:34:51,680 --> 00:34:54,520
Speaker 1: more pressure and more time and a little bit more

683
00:34:54,600 --> 00:34:57,680
Speaker 1: luck to make sure everything actually does line up against itself.

684
00:34:58,360 --> 00:35:01,040
Speaker 1: But we have used cold welding, and there's been examples

685
00:35:01,080 --> 00:35:05,320
Speaker 1: of on purpose and accidental cold welding in the environment

686
00:35:05,480 --> 00:35:06,080
Speaker 1: of space.

687
00:35:06,480 --> 00:35:08,960
Speaker 2: All right, Well, before we get to welding in space

688
00:35:09,400 --> 00:35:26,839
Speaker 2: space space, let's take a commercial break. Okay, we're back,

689
00:35:27,239 --> 00:35:31,240
Speaker 2: all right, So you promised me stories about cold welding

690
00:35:31,560 --> 00:35:34,400
Speaker 2: happening when we didn't want it to happen. But you

691
00:35:34,480 --> 00:35:35,920
Speaker 2: told me that I had to wait till we got

692
00:35:35,920 --> 00:35:38,880
Speaker 2: to the space part of the episode, which is almost certainly,

693
00:35:39,000 --> 00:35:41,799
Speaker 2: you know, always my favorite part of any episode. So

694
00:35:42,280 --> 00:35:46,520
Speaker 2: tell me about how space poses unique challenges and benefits

695
00:35:46,920 --> 00:35:47,760
Speaker 2: for welding.

696
00:35:48,200 --> 00:35:50,880
Speaker 1: Yeah, so space is sort of an obvious place you

697
00:35:50,960 --> 00:35:54,279
Speaker 1: might want to do cold welding because there's no atmosphere,

698
00:35:54,280 --> 00:35:58,000
Speaker 1: which means there's nothing to oxidize your materials. You have

699
00:35:58,080 --> 00:36:01,880
Speaker 1: a piece of bare pure cop or whatever, it's gonna

700
00:36:01,880 --> 00:36:04,120
Speaker 1: stay bare pure copper. You don't need to like scrub

701
00:36:04,160 --> 00:36:06,480
Speaker 1: the surface to get the oxides off because there's no

702
00:36:06,800 --> 00:36:10,520
Speaker 1: oxygen to make any oxides, So there's no like gas

703
00:36:10,600 --> 00:36:13,719
Speaker 1: in the middle there to interfear, no impurities, Your bare

704
00:36:13,800 --> 00:36:15,520
Speaker 1: stuff stays bear stuff.

705
00:36:15,760 --> 00:36:19,080
Speaker 2: Have we used that to our advantage yet? Like, do

706
00:36:19,160 --> 00:36:21,839
Speaker 2: we are there things that we decide we're just gonna

707
00:36:21,840 --> 00:36:23,879
Speaker 2: put together in space because we're gonna send clean stuff

708
00:36:23,960 --> 00:36:25,799
Speaker 2: up there and then assemble it with cold welding while

709
00:36:25,800 --> 00:36:26,479
Speaker 2: it gets up there.

710
00:36:26,719 --> 00:36:28,840
Speaker 1: You know, it seems like an obvious application, but I

711
00:36:28,840 --> 00:36:31,879
Speaker 1: couldn't actually find an example of times this had been

712
00:36:31,960 --> 00:36:35,320
Speaker 1: done intentionally and It seems to me like a great

713
00:36:35,360 --> 00:36:39,440
Speaker 1: idea because having any sort of like intense heat in

714
00:36:39,480 --> 00:36:42,560
Speaker 1: space seems pretty dangerous. Like the story you told us

715
00:36:42,840 --> 00:36:45,000
Speaker 1: was terrifying to me, because you know, on Earth, you

716
00:36:45,040 --> 00:36:47,760
Speaker 1: accidentally bring your heat too close to something, it melts

717
00:36:48,160 --> 00:36:49,920
Speaker 1: or maybe you get a burn or something. But in

718
00:36:49,960 --> 00:36:53,879
Speaker 1: space you destroy your spacesuit. Right, everything is so much

719
00:36:53,920 --> 00:36:56,400
Speaker 1: more dangerous out there in space. It seems like it

720
00:36:56,400 --> 00:36:59,520
Speaker 1: would be awesome to do welding without the danger of

721
00:36:59,600 --> 00:37:02,120
Speaker 1: heat or like super high electrical arcing.

722
00:37:02,320 --> 00:37:03,280
Speaker 2: Yeah, space sucks.

723
00:37:03,680 --> 00:37:07,120
Speaker 1: Space sucks exactly. I did find a couple of examples

724
00:37:07,320 --> 00:37:11,840
Speaker 1: of accidental space welding go on. In nineteen sixty five,

725
00:37:12,400 --> 00:37:16,439
Speaker 1: Gemini four was the first American spacewalk. So they sent

726
00:37:16,480 --> 00:37:18,560
Speaker 1: the guy out there, They open the hatch. He goes

727
00:37:18,600 --> 00:37:21,000
Speaker 1: out there, he space walks all around, He's having a

728
00:37:21,000 --> 00:37:22,960
Speaker 1: great time. They asked him to come back in. He

729
00:37:22,960 --> 00:37:24,799
Speaker 1: actually didn't want to come back in because he was

730
00:37:24,800 --> 00:37:28,040
Speaker 1: having so much fun. And when he came back in

731
00:37:28,160 --> 00:37:30,719
Speaker 1: and they couldn't close the hatch again, the hatch was

732
00:37:30,800 --> 00:37:33,319
Speaker 1: like stuck in the open position. They had to like

733
00:37:33,560 --> 00:37:36,279
Speaker 1: really yank on it, which is not a situation you

734
00:37:36,320 --> 00:37:37,880
Speaker 1: want to be in when you're out in space and

735
00:37:37,920 --> 00:37:39,840
Speaker 1: you like can't close the door.

736
00:37:40,239 --> 00:37:43,640
Speaker 2: No, no, you know. Apparently apparently the same thing happened

737
00:37:43,680 --> 00:37:45,840
Speaker 2: during the first Soviet space walk. Are you familiar with

738
00:37:45,880 --> 00:37:46,280
Speaker 2: this story?

739
00:37:46,600 --> 00:37:47,560
Speaker 1: No, what happened.

740
00:37:47,600 --> 00:37:49,920
Speaker 2: It doesn't have to do with cold welding. But Alexei

741
00:37:50,000 --> 00:37:52,839
Speaker 2: Leonov went out to do the first space walk ever

742
00:37:52,920 --> 00:37:55,239
Speaker 2: because I think they beat us to that too, and

743
00:37:55,360 --> 00:37:59,000
Speaker 2: he couldn't get back in, and he's known to exaggerate

744
00:37:59,040 --> 00:38:02,279
Speaker 2: his stories a bit like astronauts. That's right, Well, I

745
00:38:02,320 --> 00:38:05,440
Speaker 2: would too if I was an astronaut. But I think,

746
00:38:05,440 --> 00:38:06,960
Speaker 2: you know, like his suit. You know, he got out

747
00:38:06,960 --> 00:38:09,040
Speaker 2: into the vacuum of space and his suit sort of

748
00:38:09,080 --> 00:38:10,520
Speaker 2: like puffed up a little bit because you know, you

749
00:38:10,520 --> 00:38:14,080
Speaker 2: pressurize your suit, and after it got a little like puffy.

750
00:38:14,120 --> 00:38:16,239
Speaker 2: Or My understanding is either he couldn't get through the

751
00:38:16,280 --> 00:38:19,040
Speaker 2: hatch or he couldn't like bend the way he needed to,

752
00:38:19,120 --> 00:38:20,880
Speaker 2: so for a second there he couldn't get back in.

753
00:38:21,360 --> 00:38:23,560
Speaker 2: But I guess in both cases they managed to get

754
00:38:23,600 --> 00:38:25,800
Speaker 2: the astronaut back in and bring them back home safely,

755
00:38:25,800 --> 00:38:26,440
Speaker 2: thank goodness.

756
00:38:26,480 --> 00:38:29,759
Speaker 1: Who Well, in this case, NASA was trying to figure

757
00:38:29,800 --> 00:38:31,920
Speaker 1: out like why did the hatch get stuck? Kind of

758
00:38:31,920 --> 00:38:34,720
Speaker 1: an important thing to understand, And one of the initial

759
00:38:34,760 --> 00:38:38,279
Speaker 1: suggestions was cold welding. That maybe, like the outside of

760
00:38:38,280 --> 00:38:42,160
Speaker 1: the hatch cold welded itself to the surface of the spaceship.

761
00:38:42,400 --> 00:38:43,960
Speaker 1: And you know, this is the kind of thing we're

762
00:38:44,000 --> 00:38:46,239
Speaker 1: not used to worrying about. On the surface of the Earth.

763
00:38:46,239 --> 00:38:48,960
Speaker 1: You don't worry about like your keys cold welding themselves

764
00:38:49,000 --> 00:38:51,319
Speaker 1: to your car and stuff, because everything's covered, right, this

765
00:38:51,400 --> 00:38:54,640
Speaker 1: pint or this oxidation or just plain dirt is keeping

766
00:38:54,640 --> 00:38:57,320
Speaker 1: stuff from cold welding. But in space this is maybe

767
00:38:57,360 --> 00:39:00,200
Speaker 1: something we had to worry about, Like anytime two metals touch,

768
00:39:00,200 --> 00:39:03,120
Speaker 1: are we gonna worry about them like spot welding themselves together?

769
00:39:03,640 --> 00:39:06,520
Speaker 1: Oh my god, I know. And actually, if you look online,

770
00:39:06,520 --> 00:39:08,440
Speaker 1: there's a lot of lore about how this is an

771
00:39:08,520 --> 00:39:10,960
Speaker 1: example of cold welding. But you dig a little bit

772
00:39:10,960 --> 00:39:13,560
Speaker 1: deeper and it turns out it's actually not cold welding

773
00:39:13,680 --> 00:39:15,880
Speaker 1: at all. When it came back down to Earth, the

774
00:39:15,880 --> 00:39:18,160
Speaker 1: engineers dug into it and they found out it was

775
00:39:18,200 --> 00:39:21,120
Speaker 1: just a stuck spring that didn't compress right. So like

776
00:39:21,640 --> 00:39:23,880
Speaker 1: very normal door not working.

777
00:39:24,080 --> 00:39:27,439
Speaker 2: Okay, so you gave us like a psych moment could

778
00:39:27,440 --> 00:39:30,319
Speaker 2: be cold welding, but it's not. Is there are there

779
00:39:30,400 --> 00:39:34,560
Speaker 2: any actual cold welding examples in space or are you

780
00:39:34,640 --> 00:39:35,839
Speaker 2: just gonna keep messing with us?

781
00:39:36,400 --> 00:39:39,200
Speaker 1: No, there is one real example, and this is the

782
00:39:39,239 --> 00:39:42,040
Speaker 1: Galileo probe. And so this is a probe which went

783
00:39:42,080 --> 00:39:45,320
Speaker 1: out to explore the Solar System and take pictures of Jupiter,

784
00:39:45,440 --> 00:39:48,080
Speaker 1: for example, but it got delayed.

785
00:39:48,120 --> 00:39:51,000
Speaker 2: Wait, NASA, there were delays in a NASA project.

786
00:39:50,760 --> 00:39:54,720
Speaker 1: I know, shocking, right, And the spacecraft was like moved

787
00:39:54,719 --> 00:40:00,319
Speaker 1: across the country multiple times, and during those transports, like

788
00:40:00,400 --> 00:40:03,120
Speaker 1: shaking a bunch, and the lubrication that was supposed to

789
00:40:03,120 --> 00:40:07,440
Speaker 1: protect the metals from cold welding together eroded away. And

790
00:40:07,480 --> 00:40:09,440
Speaker 1: so when they launched this thing, and then they were

791
00:40:09,440 --> 00:40:12,920
Speaker 1: supposed to unfurl the high gain antenna, the thing that

792
00:40:13,000 --> 00:40:15,719
Speaker 1: was going to send us data back with images of

793
00:40:15,760 --> 00:40:18,400
Speaker 1: Jupiter on it, it turns out that several of the

794
00:40:18,480 --> 00:40:21,880
Speaker 1: metal struts had become cold welded together, and so it

795
00:40:22,000 --> 00:40:23,160
Speaker 1: couldn't unfurl.

796
00:40:23,560 --> 00:40:23,759
Speaker 4: No.

797
00:40:24,360 --> 00:40:27,200
Speaker 2: Oh, and they even planned for it, and that did

798
00:40:27,239 --> 00:40:29,640
Speaker 2: planning didn't work. Oh my gosh, I'm getting stressed just

799
00:40:29,680 --> 00:40:32,600
Speaker 2: thinking about it. They did they find a way around it,

800
00:40:32,680 --> 00:40:34,200
Speaker 2: or were they just stuck.

801
00:40:34,040 --> 00:40:36,320
Speaker 1: They never got the high gain intended to work. Fortunately,

802
00:40:36,320 --> 00:40:39,000
Speaker 1: there's always like redundancies on these craft, and they had

803
00:40:39,040 --> 00:40:41,440
Speaker 1: the low gain antenna which was not designed to be

804
00:40:41,520 --> 00:40:43,279
Speaker 1: used to like send data. It was more like for

805
00:40:43,400 --> 00:40:46,279
Speaker 1: control systems. But they had to reprogram it and use

806
00:40:46,320 --> 00:40:49,520
Speaker 1: it to send the actual pictures, which like delayed people

807
00:40:49,600 --> 00:40:52,200
Speaker 1: seeing these images of Jupiter. But of course you know,

808
00:40:52,239 --> 00:40:54,839
Speaker 1: we got them. It's just more like downloading on one

809
00:40:54,840 --> 00:40:57,800
Speaker 1: of those slow modems rather than your high speed internet.

810
00:40:58,120 --> 00:41:00,960
Speaker 2: Yeah, but still, oh my goodness, those engineers they figured

811
00:41:00,960 --> 00:41:02,440
Speaker 2: it out, Thank goodness. I'm sure there were a lot

812
00:41:02,480 --> 00:41:04,520
Speaker 2: of PhD students who were like, I can stay in

813
00:41:04,520 --> 00:41:07,360
Speaker 2: grad school for another year or two, that's fine, but

814
00:41:07,360 --> 00:41:09,280
Speaker 2: at least I'm gonna get my images eventually.

815
00:41:09,719 --> 00:41:09,960
Speaker 3: I know.

816
00:41:10,080 --> 00:41:11,600
Speaker 1: It's like the old days when you're down the neck

817
00:41:11,680 --> 00:41:13,640
Speaker 1: picture and you're seeing one row of pixels at a

818
00:41:13,680 --> 00:41:15,839
Speaker 1: time come across the screen and you're like, what am

819
00:41:15,880 --> 00:41:17,960
Speaker 1: I looking at? I download the right picture or not

820
00:41:18,800 --> 00:41:19,200
Speaker 1: a worry?

821
00:41:19,320 --> 00:41:21,000
Speaker 2: And you go do my computer freeze or should I

822
00:41:21,040 --> 00:41:23,200
Speaker 2: shut it down? Or should do I wait? Yeah?

823
00:41:24,080 --> 00:41:26,520
Speaker 1: Fun, So in practice, it's not really that big a problem.

824
00:41:26,560 --> 00:41:29,279
Speaker 1: It's not like when we build big space stations or

825
00:41:29,320 --> 00:41:31,680
Speaker 1: space settlement, we're gonna have to worry about cold welding

826
00:41:31,719 --> 00:41:35,279
Speaker 1: all the time. You really need like perfectly clean materials

827
00:41:35,320 --> 00:41:37,440
Speaker 1: and they have to be pressed together for long enough

828
00:41:37,680 --> 00:41:41,200
Speaker 1: for this to happen. So not really a huge concern in.

829
00:41:41,200 --> 00:41:45,160
Speaker 2: Space, all right, So are there any other applications that

830
00:41:45,200 --> 00:41:46,120
Speaker 2: we should chat about.

831
00:41:46,360 --> 00:41:49,240
Speaker 1: People have discovered that cold welling can also be really

832
00:41:49,280 --> 00:41:53,080
Speaker 1: helpful for nano circuits, Like you want to build really

833
00:41:53,120 --> 00:41:55,759
Speaker 1: really small electronics in these days, the trend is to

834
00:41:55,800 --> 00:41:58,840
Speaker 1: build like tinier and tinier microchips, which use less power

835
00:41:58,880 --> 00:42:01,920
Speaker 1: and can be squeezed into all sorts of scenarios, so

836
00:42:01,960 --> 00:42:04,560
Speaker 1: you can have like microchips in your cereal or whatever

837
00:42:04,600 --> 00:42:09,640
Speaker 1: you need, you know exactly, you know, they can count

838
00:42:09,640 --> 00:42:14,920
Speaker 1: your calories for you, right exactly. Anyway, nanoscale fabrication is

839
00:42:15,040 --> 00:42:18,640
Speaker 1: tricky because spot welding is very hard. When it's really

840
00:42:18,680 --> 00:42:21,719
Speaker 1: really tiny, you know, basically need like tiny sources of

841
00:42:21,760 --> 00:42:25,359
Speaker 1: heat or you need this electricity to arc perfectly. Well,

842
00:42:25,360 --> 00:42:27,880
Speaker 1: what they've discovered is that you can do cold welding

843
00:42:27,960 --> 00:42:31,200
Speaker 1: for nanofabrication. I read this paper that came out of

844
00:42:31,320 --> 00:42:34,120
Speaker 1: nature like ten years ago where they had ultra thin

845
00:42:34,200 --> 00:42:37,520
Speaker 1: gold nano wires and you just bring them together and

846
00:42:37,560 --> 00:42:41,840
Speaker 1: if the edges touch, boom, they cold well together within seconds.

847
00:42:41,960 --> 00:42:45,239
Speaker 1: You don't even need a lot of pressure. Whoa yeah.

848
00:42:45,280 --> 00:42:48,719
Speaker 1: And these wires once they've cold welded together essentially as

849
00:42:48,800 --> 00:42:51,840
Speaker 1: like a near perfect bond. They did all these tests

850
00:42:51,840 --> 00:42:55,359
Speaker 1: of like the electrical conductivity and a crystal orientation, and

851
00:42:55,400 --> 00:42:58,960
Speaker 1: it's as if it was always just one wire. So

852
00:42:59,040 --> 00:43:01,760
Speaker 1: this means, Kelly, do need your children, with like their

853
00:43:01,800 --> 00:43:05,040
Speaker 1: delicate little fingers to do tiny little arc welding on

854
00:43:05,080 --> 00:43:06,040
Speaker 1: our nano circuits?

855
00:43:06,560 --> 00:43:08,960
Speaker 2: Oh? Good, good, because that was gonna be a thing.

856
00:43:10,920 --> 00:43:12,560
Speaker 1: But it might be that we can send your kids

857
00:43:12,560 --> 00:43:16,239
Speaker 1: down the space to do space construction jobs without arc welding. Right,

858
00:43:16,600 --> 00:43:16,880
Speaker 1: how do you.

859
00:43:16,840 --> 00:43:19,520
Speaker 2: Feel about that any of the episode? Nope, none of

860
00:43:19,520 --> 00:43:21,239
Speaker 2: the episode. None.

861
00:43:21,480 --> 00:43:23,160
Speaker 1: If your kids grow up and they want to work

862
00:43:23,160 --> 00:43:28,600
Speaker 1: construction in space, you're gonna say no, yes, no. You

863
00:43:28,640 --> 00:43:30,560
Speaker 1: didn't think about that deeply at all. It was just

864
00:43:30,680 --> 00:43:31,719
Speaker 1: like a straight up no.

865
00:43:32,200 --> 00:43:34,160
Speaker 2: I hope they don't go that route, but if they do,

866
00:43:34,280 --> 00:43:36,600
Speaker 2: I will support them grudgingly.

867
00:43:38,280 --> 00:43:40,200
Speaker 1: Well, I think cold welding is super fascinating, and what

868
00:43:40,239 --> 00:43:41,680
Speaker 1: it tells me is that there's a lot more to

869
00:43:41,760 --> 00:43:45,319
Speaker 1: understand about how these particles weave themselves together to make

870
00:43:45,360 --> 00:43:48,680
Speaker 1: the sort of macroscopic materials that we're familiar with, and

871
00:43:48,719 --> 00:43:50,920
Speaker 1: that there's still sort of magic left. I mean, I'm

872
00:43:50,920 --> 00:43:54,440
Speaker 1: not talking about Vermont Farmer magic. I'm talking about accomplishing

873
00:43:54,480 --> 00:43:57,200
Speaker 1: things that seem impossible to us, you know, just like

874
00:43:57,520 --> 00:43:59,719
Speaker 1: sticking two pieces of metal together and make them into

875
00:43:59,760 --> 00:44:03,320
Speaker 1: one metal. Every time there's an advancement in material science,

876
00:44:03,400 --> 00:44:06,600
Speaker 1: it feels almost like we're creating real magic.

877
00:44:06,920 --> 00:44:09,360
Speaker 2: I agree, but I still feel like the main takeaway

878
00:44:09,400 --> 00:44:11,840
Speaker 2: for me is one more thing to worry about in

879
00:44:11,840 --> 00:44:16,080
Speaker 2: space because cold welding going wrong. We should have gotten

880
00:44:16,080 --> 00:44:16,760
Speaker 2: that in the book.

881
00:44:17,960 --> 00:44:19,960
Speaker 1: I think you already had like a thousand reasons not

882
00:44:20,040 --> 00:44:21,680
Speaker 1: to build in space in your book. You don't need

883
00:44:21,719 --> 00:44:27,680
Speaker 1: another reason. Yeah, I guess beat that dead horse. And

884
00:44:27,719 --> 00:44:31,520
Speaker 1: as much as I'm jokingly negative about chemistry, it does

885
00:44:31,680 --> 00:44:35,200
Speaker 1: really give us access to the microscopic nature of materials.

886
00:44:35,480 --> 00:44:38,360
Speaker 1: It's the easiest way to see these emergent properties, to

887
00:44:38,400 --> 00:44:41,480
Speaker 1: see how something can be sticky or shiny or brittle

888
00:44:41,920 --> 00:44:44,759
Speaker 1: because of the way the particles inside it interact and

889
00:44:45,000 --> 00:44:48,279
Speaker 1: cold welding is just another manifestation of that that our

890
00:44:48,320 --> 00:44:51,640
Speaker 1: world really is dominated by the microscopic rules that somehow

891
00:44:51,719 --> 00:44:56,360
Speaker 1: bubble up to make this incredible variety of behaviors and phenomena.

892
00:44:56,680 --> 00:44:58,560
Speaker 2: Yeah, I gotta give it to you chemistries pretty much.

893
00:44:58,560 --> 00:45:01,960
Speaker 1: It is kind of magic, dang it. Yeah.

894
00:45:02,160 --> 00:45:07,840
Speaker 2: Yeah, my chemistry professors kept telling me that, but but

895
00:45:07,960 --> 00:45:08,759
Speaker 2: now I believe it.

896
00:45:09,200 --> 00:45:11,600
Speaker 1: Finally, thirty years later, I've learned it too.

897
00:45:13,239 --> 00:45:15,360
Speaker 2: Thirty Oh, why you might be on it?

898
00:45:17,040 --> 00:45:19,200
Speaker 1: All right? Well, thanks Kelly for joining us on this

899
00:45:19,480 --> 00:45:23,319
Speaker 1: tour of chemistry and magic and this dive into how

900
00:45:23,360 --> 00:45:24,520
Speaker 1: cold welding works.

901
00:45:24,840 --> 00:45:25,680
Speaker 2: Thanks for having me.

902
00:45:25,719 --> 00:45:28,200
Speaker 1: All right, Everyone, keep wondering about how the universe works

903
00:45:28,200 --> 00:45:31,000
Speaker 1: and send us your questions. This episode was inspired by

904
00:45:31,040 --> 00:45:34,239
Speaker 1: listeners who wanted to understand how cold welding works. If

905
00:45:34,280 --> 00:45:37,160
Speaker 1: you have ideas for things you'd like to hear us explore,

906
00:45:37,239 --> 00:45:40,160
Speaker 1: please don't be shy. Write to me two questions at

907
00:45:40,280 --> 00:45:44,520
Speaker 1: Danielandhorge dot com. Tune in next time. Thanks very much.

908
00:45:49,280 --> 00:45:52,440
Speaker 1: For more science and curiosity, come find us on social media,

909
00:45:52,560 --> 00:45:57,120
Speaker 1: where we answer questions and post videos. We're on Twitter, Discord, Instant,

910
00:45:57,200 --> 00:46:00,640
Speaker 1: and now TikTok. Thanks for listening, and remember that Daniel

911
00:46:00,680 --> 00:46:04,120
Speaker 1: and Jorge Explain the Universe is a production of iHeartRadio.

912
00:46:04,400 --> 00:46:09,520
Speaker 1: For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts,

913
00:46:09,680 --> 00:46:12,040
Speaker 1: or wherever you listen to your favorite shows.