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Speaker 1: When you save that picture of your cute dog or

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Speaker 1: cat on your computer, you expect it to be there

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Speaker 1: later when you want to show it off or send

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Speaker 1: it to your favorite podcaster. Side note, Thanks for all

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Speaker 1: the pet pictures. We love them and keep them coming.

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Speaker 1: But how can you be sure that the information you

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Speaker 1: store in your computer will be there uncorrupted when you

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Speaker 1: come back for it? Is our digital information infrastructure robust

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Speaker 1: or fragile. Since this is a physics podcast, you might

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Speaker 1: be wondering if there are physics reasons that your data

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Speaker 1: might not be safe. There are in this case. Unfortunately,

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Speaker 1: it's not aliens. I'd love if it were aliens. But

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Speaker 1: the concern is radiation from space. We know that it

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Speaker 1: can hurt our bodies and rewrite our DNA, which are

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Speaker 1: essentially biological hard drives. Can it also erupt our computers

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Speaker 1: cosmic ray bitflips? What does that mean for data centers

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Speaker 1: in space or puppies in space or pictures of cats

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Speaker 1: on Mars? Oh my? Welcome to Daniel and Kelly's Extraordinary

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Speaker 1: Digital Universe.

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Speaker 2: Hello. I'm Kelly water Smith. I study parasites and space,

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Speaker 2: and if something goes wrong with my computer, I have

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Speaker 2: no clue how to deal with it.

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

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Speaker 1: an experimental list but really all of my sciences on

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Speaker 1: the computer.

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Speaker 2: Now, you told me that you were thinking about going

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Speaker 2: into computer science before you decided to go into particle physics.

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Speaker 2: So are you the person that everyone goes to when

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Speaker 2: they have computer problems or now in the era of

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Speaker 2: like MacBooks, is it just like two hard for you

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Speaker 2: to troubleshoot? Or yeah? Are you? Are you the go

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Speaker 2: to person?

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Speaker 1: I'm definitely the tech support person in my family. You know,

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Speaker 1: why won't this thing load? Or I want to print

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Speaker 1: from here? Why can't I? For some reason, everybody comes

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Speaker 1: to me, even though like computer science undergraduate degrees is

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Speaker 1: mostly about like red black trees and sorting and whatever,

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Speaker 1: and you don't really get expertise in that kind of stuff.

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Speaker 1: Nothing useful, nothing useful exactly. But you have very recently

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Speaker 1: become aware of how fragile computers are.

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Speaker 2: Sure, Yes, I'm coming to you from Zex's chromebook because

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Speaker 2: I have with in one year, broken my computer screen

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Speaker 2: for the second time and it is in the shop again.

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Speaker 1: And have you managed to blame this on like weird

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Speaker 1: particles from space.

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Speaker 2: No, no, what, just a lot of clumsy members in

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Speaker 2: the Wienersmith household. Fifty percent of the time it was

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Speaker 2: my fault. The other fifty percent was my adorable children.

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Speaker 1: Well, maybe today's episode is going to give somebody over

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Speaker 1: there excuse I didn't break that computer screen, even if

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Speaker 1: my footprint is on it. It was cosmic rays.

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Speaker 2: In this case, it was their teeth marks. But yes,

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Speaker 2: maybe maybe they can blame a really amazing combination of

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Speaker 2: particle rays that came in just the right pattern.

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Speaker 1: Well, today's topic really connects with a few of my

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Speaker 1: interests because, of course I like thinking about cosmic rays.

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Speaker 1: They are particles from space, and everything I do is

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Speaker 1: on the computer. Plus, this is a concept that appears

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Speaker 1: a lot in popular science, cosmic rays flipping bits on computers,

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Speaker 1: And I thought, let's make sure everybody out there really

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Speaker 1: understands how that works and how serious a problem it is,

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Speaker 1: especially with all this talk of sending data centers into space.

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Speaker 2: Does it occur a lot in pop science? I can't

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Speaker 2: think of a single example.

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Speaker 1: Wow, maybe I read the wrong pop science.

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Speaker 2: Or maybe I read the wrong pop science. Can you

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Speaker 2: name five examples? No? I'm just kidding. Name one. I'm

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Speaker 2: winny h.

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Speaker 1: You put me on the spot, and I cannot name

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Speaker 1: a single one right now off the top of my head.

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Speaker 1: But I have the feeling like this is something that

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Speaker 1: I hear a lot in popular science, or that people

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Speaker 1: in general know a little bit about, but my benefit

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Speaker 1: from understanding, like the real physics that underlies all of

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Speaker 1: this stuff, so that in the future, when there is

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Speaker 1: an onslaught of popular science articles after we launched the

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Speaker 1: first data centers into space, everyone will be well equipped.

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Speaker 2: Well, but I mean, this is a thing that could

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Speaker 2: be important for our lives personally, So like, not only

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Speaker 2: could this be important if we put data centers in space,

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Speaker 2: but for example, one of our listeners, Simon, sent us

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Speaker 2: this article where there was a plane that was flying

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Speaker 2: and all of a sudden it dropped really fast, and

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Speaker 2: nobody died. Some people did get hurt. But the thought

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Speaker 2: was that some part of the computer on the plane

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Speaker 2: got hit by a cosmic ray. It flipped a bit,

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Speaker 2: which Daniel's going to explain, and that sort of messed

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Speaker 2: up the control of the plane and the plane dropped

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Speaker 2: really quick and some people got hurt. And so this

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Speaker 2: is like a thing that could impact our lives, and

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Speaker 2: at some point I have another space related story that

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Speaker 2: I'll tell. So you know, this isn't just a thing

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Speaker 2: that might be important in the future. It's a thing

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Speaker 2: that matters. Now.

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Speaker 1: Hey, that sounds a lot to me like a popular

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Speaker 1: science article about a cosmic ray.

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Speaker 2: Bitflip, I thought you said a sci fi thing.

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Speaker 1: Oh are you too popular? No play the tape, we said,

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Speaker 1: POPSI this is a concept that appears a lot in

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Speaker 1: popular science.

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Speaker 2: Does it occur a lot in pop science?

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Speaker 1: Pop science? Popular science? Pop science, popular science, popular science articles? Oh?

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Speaker 2: I thought you said sci fi? All right? All right, anyway,

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Speaker 2: Daniel and I aren't communicating well today, But that's all right.

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Speaker 2: We're gonna move forward. I'll give you the win on

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Speaker 2: that one, all right. So let's let's lay some groundwork here.

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Speaker 1: But before we explain how everything works. I was wondering

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Speaker 1: what people knew about how cosmic rays could mess up

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Speaker 1: those pictures of your puppies. So I went out there

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Speaker 1: to ask our volunteers their thoughts, without any googling, of course,

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Speaker 1: whether cosmic rays can corrupt computers. Here's what people had

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Speaker 1: to say.

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Speaker 3: Perhaps theris magnetosphere is protecting us from that issue.

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Speaker 1: Cosmic rays are nasty.

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Speaker 3: Of course, Cosmic rays can corrupt computer data. Cosmic rays

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Speaker 3: definitely can flip bits in computer systems.

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Speaker 1: I'm sure cosmic rays can cause problems or another. I

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Speaker 1: can with some dish drawers. I'm not sure.

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Speaker 3: Cosmic rays can absolutely corrupt computer data by flipping essential bits,

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Speaker 3: even when we build in redundancy. I think there have

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Speaker 3: even been stories of car accidents attributed to cosmic ray disruptions.

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Speaker 1: I would think so because the higher frequency spectrum could

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Speaker 1: penetrate I wouldn't imagine across the computer barriers.

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Speaker 3: Cosmic rays and computers do not get along. I think

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Speaker 3: cosmic rays messing with our computers all the time, and

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Speaker 3: that's why we have checksums and stuff. Yes, I know

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Speaker 3: for certain in space, electronics that are exposed to cosmic

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Speaker 3: rays do have a risk of that bits getting flipped.

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Speaker 1: Absolutely, cosmic rays can corrupt data. Satellites can be corrupted

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Speaker 1: by cosmic rays, so they have to be hardened and redundant.

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Speaker 1: I'm not sure about on the surface of the Earth, though,

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Speaker 1: a cosmic ray flipped a bit inside the game as

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Speaker 1: the player was playing and basically cheated for them. They

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Speaker 1: would be able to alter the bit in a data stream.

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Speaker 2: So yes, great answers. As always, I think when someone

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Speaker 2: says can X mess up y, my answer is usually yeah,

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Speaker 2: probably as like I'm negative. But I don't think I

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Speaker 2: really knew that this was something to worry about until

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Speaker 2: I was researching a city on Mars and we came

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Speaker 2: across some stories about like space radiation messing up computers.

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Speaker 1: Yeah. People think of their computers as robust, like you

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Speaker 1: put a one in memory somewhere, it's going to be there.

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Speaker 1: It's not like somethuzz if you a paper that can

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Speaker 1: get overwritten or destroyed or whatever. But in reality, these

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Speaker 1: are physical systems and they live in the universe, and

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Speaker 1: the universe is not always a friendly place to store

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Speaker 1: to your data.

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Speaker 2: Yeah, and you're not supposed to bite the screen either.

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Speaker 2: So let's start with understanding how computers store data because

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Speaker 2: I still find this like slightly magical, which which is

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Speaker 2: kind of great. So how are computers storing information?

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Speaker 1: Yeah, it's a great question, and fundamentally computer store information

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Speaker 1: using quantum mechanics. Right, you could store information on just

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Speaker 1: like a long tape, like the way a Turing machine does.

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Speaker 1: You're like writing ones and zeros and principle, it can

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Speaker 1: be anything, but you want it to be compact, so

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Speaker 1: you could have like lots and lots of ones and

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Speaker 1: zeros and not have it take up a whole room.

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Speaker 1: And you want it to be fast so you can

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Speaker 1: read it out really quickly and you're not waiting an

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Speaker 1: hour for that picture of your puppies to load. And

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Speaker 1: so we make it small and fast by using atomic systems.

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Speaker 1: And at its core, all these atomic systems are built

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Speaker 1: on semiconductors, which is why you hear about silicon so much.

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Speaker 1: Silicon is a semiconductor. Well, what does that mean semiconductors, Well,

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Speaker 1: semiconductors sit between insulators which don't conduct electricity and conductors

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Speaker 1: like metals, which conduct a lot of electricity. And understand

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Speaker 1: why that is. You have to understand something about the

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Speaker 1: atomic structure here, and we're used to thinking about atoms

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Speaker 1: by themselves. You have like energy levels, and a silicon

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Speaker 1: atom has like where electrons can be. There's like a

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Speaker 1: ladder of them, right, and they can absorb and emit photons.

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Speaker 1: This kind of stuff is like a very discrete set

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Speaker 1: of energy levels, and that's true for atoms. And if

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Speaker 1: you have, like a gas of silicon, it's going to

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Speaker 1: emit photons at certain energy levels and absorb at those

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Speaker 1: energy levels, and that's all cool. So that's atomic physics.

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Speaker 2: Is atomic physics another word for chemistry, because it kind

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Speaker 2: of sounds like it's another word for chemistry.

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Speaker 1: It's the foundation of all chemistry. Yet everything in chemistry

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Speaker 1: comes out of those energy levels. And then it gets

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Speaker 1: more complicated because you have atoms binding with each other

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Speaker 1: and sharing electrons. And if you take that too, you

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Speaker 1: get things like solids where you have a whole lattice

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Speaker 1: of atoms, and now you don't have to solve these

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Speaker 1: problems just for one electron. You have to think about

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Speaker 1: what happens to an electron that's shared among many, many atoms.

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Speaker 1: And so instead of thinking about a lattice of silicon,

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Speaker 1: atoms is like each a bunch of individual atoms with

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Speaker 1: their own energy levels. These things overlap because they're so close,

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Speaker 1: and so they spread these sharp atomic energy levels into bands.

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Speaker 1: So we talked about bands of electron energy levels. So

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Speaker 1: you shouldn't think about electron in a piece of silicon

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Speaker 1: is like this one belongs to that atom, or belongs

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Speaker 1: to this atom, or belongs to this other atom. It

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Speaker 1: moves smoothly right the ions the nuclei are bound together,

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Speaker 1: they're sort of like fixed in a lattice, and the

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Speaker 1: electrons are all moving around, and there's different energy levels there,

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Speaker 1: which roughly get grouped into two different kinds of bands.

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Speaker 1: There's the valence bands. Those are the low energy ones

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Speaker 1: where the electrons are mostly local and bound to a

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Speaker 1: specific ion. But then there's above that, there's the conduction band,

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Speaker 1: are usually empty and the electrons can flow around. So

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Speaker 1: if you have, for example, a metal, then there's a

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Speaker 1: very small gap between the valiance band and the conduction band,

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Speaker 1: and the electrons that fill up the valance band can

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Speaker 1: jump up to the conduction band like getting on the

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Speaker 1: highway really easily, and flowing all around the metal. So

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Speaker 1: if you put an electric field near a conductor, the

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Speaker 1: electrons will jump up to the conduction band and flow

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Speaker 1: all around. If you have a big gap there, like

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Speaker 1: no entrances to your freeway, then the electrons are all

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Speaker 1: stuck in their local area, and even if you put

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Speaker 1: an electric field over it, they're really not going to move.

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Speaker 1: So that's how to understand an insulator and a conductor

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Speaker 1: or something we call a metal. Usually a semiconductor like silicon,

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Speaker 1: is something where that gap is sort of like in between.

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Speaker 1: It's not really big, it's not really small. All that

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Speaker 1: silicon lithography helps you do some fancy local chemistry to

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Speaker 1: make a silicon dioxide or silicon nitride that changes its conductivity,

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Speaker 1: which means you can now separate components and dielectrics and

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Speaker 1: whatever you need to build circuits. And so you can

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Speaker 1: design really really small electrical circuits just by doping the

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Speaker 1: silicon in various ways.

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Speaker 2: Okay, so the reason you want to use silicon is

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Speaker 2: because it's helpful to have something that's in between, because

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Speaker 2: you well, so, like, why wouldn't you just want to

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Speaker 2: have a full insulator or a full conductor on your

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Speaker 2: chip as opposed to just using silicon everywhere and then

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Speaker 2: tinkering with it. Tinkering sounds possibly more complicated than just

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Speaker 2: putting conductors in some places.

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Speaker 1: Yeah, you could construct it out of just conductors wrapped

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Speaker 1: in insulators, and that's basically how you build circuits on

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Speaker 1: your bench, Right, you have like copper wires wrapped in rubber, right,

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Speaker 1: and that works, But it's really hard to do that

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Speaker 1: at a micro scale. To manufacture that stuff, and to

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Speaker 1: do it cheaply and at high volume. It's easier to

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Speaker 1: take silicon, which can be tweaked in either direction. It

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Speaker 1: turns out to be a lot easier to tweak it

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Speaker 1: than to just like build it from scratch, okay.

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Speaker 2: And so to tweak it, you just like flick some

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Speaker 2: germanium on it, and now you're good.

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Speaker 1: Yeah. Essentially we have a whole episode about how silicon

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Speaker 1: lithography works, and people should dig into the details there.

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Speaker 1: There's a lot of nuance that's missed in this summary here,

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Speaker 1: but roughly, that's why you want to start with silicon,

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Speaker 1: because you can easily change it to be a conductor

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Speaker 1: or an insulator.

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Speaker 2: I'll go check that out. My memory is just the

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Speaker 2: pits lately, Okay. So now we've got our semiconductors.

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Speaker 1: Yeah, and so you can use that to build all

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Speaker 1: sorts of microscopic bits of your circuits out of silicon.

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Speaker 1: But keep that in mind for later when we're talking

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Speaker 1: about what happens when a cosmic ray tears through a

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Speaker 1: piece of silicon. So, now you have the silicon, and

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Speaker 1: then you want to build a computer, how do you

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Speaker 1: actually use it to store memory? So your computer has

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Speaker 1: several different kinds of memory depending on your need. So

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Speaker 1: the memory you might think about are things like RAM. Right,

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Speaker 1: These are like things your computer remembers when it's turned on,

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Speaker 1: but if your turn off, the computer is empty. So

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Speaker 1: like loading a program into memory so that your computer

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Speaker 1: can run it. Right. So this is you know, random

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Speaker 1: access memory, and these days it's called d RAM dynamic

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Speaker 1: random access memory. And random access just means that you

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Speaker 1: can like get a piece of informmation from anywhere. You

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Speaker 1: don't have to like read it in order, like a book.

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Speaker 1: You can just have an index. You can say, tell

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Speaker 1: me what's stored here, tell me what's stored there. Song.

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Speaker 1: As you know the index, you can look it up.

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Speaker 2: Okay, So I've got a semiconductor which allows me to

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Speaker 2: move electrons around.

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Speaker 1: And to build circuits. And so now the question is

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Speaker 1: how do you use little electrical circuits to store information?

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Speaker 1: And so DRAM does this by using a capacitor connected

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Speaker 1: to a transistor. So a capacitor physically, if you build

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Speaker 1: a large one, is just like two surfaces insulated from

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Speaker 1: each other that are separated, and so you can have

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Speaker 1: like a charge stored across them. You can put a

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Speaker 1: bunch of electrons on one side and then you have

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Speaker 1: like a voltage across the capacitor. And so capacitor is

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Speaker 1: very useful for all sorts of things circuits. But in

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Speaker 1: this case you can just ask like, well, is there

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Speaker 1: voltage on it? If so, I'm going to call that

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Speaker 1: a one. If there's no voltage across it, I'm going

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Speaker 1: to call that a zero. You just need some sort

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Speaker 1: of microscopic state which you can control and you can

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Speaker 1: read out, and then you assign the meaning of one

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Speaker 1: to one of the states and zero to the other state.

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Speaker 2: Okay, but so what could actually be happening in the

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Speaker 2: capacitor is there's a lot of different ways that you

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Speaker 2: could have more charge on one side and less charge

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Speaker 2: on the other, but it all gets sort of summarized

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Speaker 2: down to one in zero.

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Speaker 1: Yeah, exactly, because this is digital logic. In the end,

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Speaker 1: everything is analog, like the universe is mostly analog, but

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Speaker 1: we assign digital meaning to it. And as these things

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Speaker 1: get smaller and faster than the amount of charge to

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Speaker 1: capacitor holds gets really really small, so that it's quick

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Speaker 1: to read out, it's quick to assign, and it's easy

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Speaker 1: to make small. So in this case, it's like a

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Speaker 1: few tens of thousands of electrons hold the charge. And

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Speaker 1: you can imagine more complicated systems. If you don't want

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Speaker 1: to use binary logic, you want to use trinary, you

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Speaker 1: could have like two different threashs. You could say zero

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Speaker 1: is anywhere from zero to ten thousand electrons, and a

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Speaker 1: one is ten thousand to twenty thousand electrons, and anything

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Speaker 1: above twenty thousand I'm gonna call it two if you

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Speaker 1: have trinary logic, but we use binary. So it's like

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Speaker 1: zero or somewhere above ten thousand electrons or ten to

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Speaker 1: thirty fempto coulums. And so there's a capacitor that holds

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Speaker 1: it and then a transistor which allows you access to it.

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Speaker 1: And so that's the basis of DRAM. And this requires

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Speaker 1: constant power. When you turn off the computer, that charge

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Speaker 1: dissipates and it's gone, which is why when you turn

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Speaker 1: off your computer, it doesn't remember anymore what was in

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Speaker 1: its memory.

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Speaker 2: Okay, so you've got the semiconductor, and those electrons are

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Speaker 2: jumping up into the highway and they're getting moved around

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Speaker 2: in the capacitor so that they can store up these

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Speaker 2: ones in these zeros.

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Speaker 1: And it's critical there that you have conductors, Like the

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Speaker 1: plates on the capacity are made of conductors and insulators

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Speaker 1: between the plates so that the chargers don't just flow across.

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Speaker 2: Okay, all right, so you want them to move and

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Speaker 2: then you want them to stay once you've.

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Speaker 1: Moved there, exactly, Okay, exactly, But these things don't work great.

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Speaker 1: Like there's a leakage there because these things are super

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Speaker 1: duper small and the insulator isn't perfect, and so every

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Speaker 1: sixty four milliseconds or so, it just like leaks away.

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Speaker 1: So your computer has to constantly refresh your RAM every

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Speaker 1: sixty milliseconds or so, it rewrites the number onto it.

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Speaker 1: It's not very stable.

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Speaker 2: That doesn't sound like a great system. I mean, I

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Speaker 2: mean it seems to work great. I love my computer

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Speaker 2: when it's not in the shop.

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Speaker 1: It's kind of amazing that it works as well as

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Speaker 1: it does. You don't just like call up a picture

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Speaker 1: and it's like totally corrupted.

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Speaker 2: Yeah.

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Speaker 1: Then there's another kind of memory, which is in your CPU.

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Speaker 1: So your computer basically has like a hard drive to

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Speaker 1: store information. And then there's the CPU, the central processing

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Speaker 1: unit that does all the actual calculations. Then it has

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Speaker 1: access to the main memory that we just talked about,

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Speaker 1: the RAM, But when it's doing the calculations, it slurps

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Speaker 1: stuff from the RAM into a special super fast memory

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Speaker 1: called the CASH, which is close to the CPU so

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Speaker 1: that it doesn't have to go all the way to

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Speaker 1: memory which turns out to be a little bit slow.

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Speaker 1: So you have these hierarchies of memory in your computer

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Speaker 1: which are smaller and faster or bigger and slower. So

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Speaker 1: SRAM is the fastest, smallest memory. It's like right there

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Speaker 1: next to the CPU. It's like if you're trying to

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Speaker 1: do your household budget, you don't keep all of the

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Speaker 1: information right in front of you. You have like a

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Speaker 1: sheet of paper or a spreadsheet with like the critical

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Speaker 1: details right in front of you that you're calculating right now.

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Speaker 1: The CPU's CASH is essentially like its.

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Speaker 2: Little worksheet and sm SRAM stands for is that slow

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Speaker 2: random access memory? Is that what it stands for.

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Speaker 1: It stands for a static random access memory, okay, as

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Speaker 1: opposed to dynamic, which is the kind you have for

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Speaker 1: your most of your memory. And this is cool because

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Speaker 1: it's built by a pair of logic gates usually, so

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Speaker 1: it's built using not gates. Sont gits are something where

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Speaker 1: if you take in a one, you output a zero,

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Speaker 1: if you take in a zero, you output a one.

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Speaker 1: So it's like a basic logic gate in the same

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Speaker 1: categories like and gates you know that require two ones

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Speaker 1: to output a one, or an ore gate that requires

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Speaker 1: either of the inputs to be one to output a one.

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Speaker 2: Oh yes, of course.

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Speaker 1: And these again are built on top of transistors which

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Speaker 1: are made of silicon, So you can tie a few

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Speaker 1: transistors together to make a nand gate or an and

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Speaker 1: gate or a knot gate. All these basic digital logics

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Speaker 1: are built on top of the same fundamental technology, which

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Speaker 1: are silicon transistors which have these various levels of doping

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Speaker 1: so they can do what they need to do. And

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Speaker 1: so the way SRAM works is you have two knock

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Speaker 1: gates looped on each other. It's kind of silly, but

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Speaker 1: it works really amazingly well. Like, say I have two

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Speaker 1: knock gates. If the first one has an output value

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Speaker 1: of one, and then you feed that into the second one,

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Speaker 1: the second one is going to have an output value

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Speaker 1: of zero, right, feed the output of the second one

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Speaker 1: back into the first one, and it's going to keep

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Speaker 1: the first one having an output value of one because

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Speaker 1: it's input with zero. And so it's just sort of

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Speaker 1: like if you have two of these things in series

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Speaker 1: and then looped on each other, they support each other,

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Speaker 1: and there's two stable states here. Either the first one

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Speaker 1: is one and the second one is zero, or the

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Speaker 1: first one is zero and the second one is one,

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Speaker 1: and either way they just constantly support each other, confirming

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Speaker 1: each other.

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Speaker 2: Okay, I'm following, but I feel like the big picture

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Speaker 2: here for anyone who is maybe having a little trouble following,

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Speaker 2: is that in all of these cases, what's happening is

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Speaker 2: we are very carefully keeping track of where electrons are going,

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Speaker 2: and they need to be going in particular places and

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Speaker 2: staying there.

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Speaker 1: And so you have your DRAM, which is a capacity

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Speaker 1: and a transistor. You have your s RAM, which has

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Speaker 1: this pair of knock gates which you're keeping your information.

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Speaker 1: And these are more robust than your DRAM because they

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Speaker 1: don't leak the same way. But these transistors are super

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Speaker 1: duper small and so like a little bit of tweaking

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Speaker 1: can corrupt them. And then the last kind of memory

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Speaker 1: in your computer is the hard drive. This is the

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Speaker 1: most robust, the thing where if you turn it off,

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Speaker 1: it will stay there. You can put your picture of

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Speaker 1: your puppy on your hard drive and turn your computer

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Speaker 1: off and on it's still there. And this is also

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Speaker 1: the slowest kind of memory and the biggest and these

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Speaker 1: days this uses flash technology, which essentially like an insulated

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Speaker 1: box and you try to trap some electrons in there,

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Speaker 1: or you let the electrons out, and it's insulated so

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Speaker 1: the electrons can't leave. And essentially you say, if the

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Speaker 1: electrons are trapped in there, then it's going to be

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Speaker 1: a one. If the electrons are not trapped, it's going

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Speaker 1: to be a zero. And so this is like a

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Speaker 1: really big energy barrier that's very robust and it's very

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Speaker 1: hard to pertur, but it's kind of slow, which is

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Speaker 1: why you use it for your biggest, slowest memory, like

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Speaker 1: your hard drives.

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Speaker 2: Does your computer start with all the electrons that it

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Speaker 2: needs and just move them around or does it pull

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Speaker 2: electrons out of the environment when it needs them?

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Speaker 1: Why are you Oh, great question? No, I love this

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Speaker 1: question because it touches on like, you know, electrons versus electricity, right,

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Speaker 1: and mostly electricity is the motion of electrons, So you're

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Speaker 1: not like running out of electrons in a sense. But

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Speaker 1: people confuse these two things and they like to talk

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Speaker 1: about electrons when they mean electricity. And remember that these

437
00:22:02,280 --> 00:22:05,800
Speaker 1: numbers of electrons are super due per tiny, right, Like

438
00:22:05,840 --> 00:22:08,760
Speaker 1: the number of electrons in silicon is like, you know,

439
00:22:08,840 --> 00:22:11,679
Speaker 1: ten to the twenty nine per gram or some crazy number.

440
00:22:12,200 --> 00:22:14,320
Speaker 1: So if you're talking about circuits that need like ten

441
00:22:14,359 --> 00:22:17,879
Speaker 1: thousand electrons, it's really just you're never going to run

442
00:22:17,920 --> 00:22:21,399
Speaker 1: out of electrons. So electrons are everywhere. We're all just

443
00:22:21,480 --> 00:22:24,160
Speaker 1: living in a vast ocean of electrons. It's about controlling

444
00:22:24,440 --> 00:22:27,359
Speaker 1: where they are and where they aren't and where they go. Okay,

445
00:22:27,440 --> 00:22:29,160
Speaker 1: you don't need to recharge your electrons, but it sounds

446
00:22:29,200 --> 00:22:31,719
Speaker 1: to me like a really fun scam we can sell people,

447
00:22:31,760 --> 00:22:33,920
Speaker 1: like let's top up your electrons.

448
00:22:34,640 --> 00:22:36,120
Speaker 2: All right, Well, Daniel and I are going to think

449
00:22:36,119 --> 00:22:39,320
Speaker 2: of how we can monetize electrons. See if you can

450
00:22:39,359 --> 00:22:42,280
Speaker 2: hear are commercial for it during the break, and we'll

451
00:22:42,280 --> 00:23:04,200
Speaker 2: be back in a moment. We're back. Daniel just gave

452
00:23:04,240 --> 00:23:08,040
Speaker 2: us a great explanation for how computers store information, and

453
00:23:08,080 --> 00:23:10,360
Speaker 2: now we're going to hear about how cosmic rays can

454
00:23:10,600 --> 00:23:14,280
Speaker 2: mess that all up. So, Daniel, what is a cosmic ray.

455
00:23:14,320 --> 00:23:17,119
Speaker 2: I'm sure physicists have this absolutely nailed down.

456
00:23:21,359 --> 00:23:25,960
Speaker 1: Cosmic rays are basically just particles from space. Right. Rays

457
00:23:26,119 --> 00:23:28,080
Speaker 1: is just like a generic name for a particle, or

458
00:23:28,119 --> 00:23:30,640
Speaker 1: sort of an old fashioned name, and cosmic just means

459
00:23:30,720 --> 00:23:34,200
Speaker 1: it comes from space somewhere, and the Earth is constantly

460
00:23:34,240 --> 00:23:37,680
Speaker 1: being hit by particles from space. Because space is not empty.

461
00:23:37,760 --> 00:23:39,600
Speaker 1: You might think of it as like a grand vacuum,

462
00:23:39,640 --> 00:23:42,840
Speaker 1: but really it's filled with particles, just much lower density

463
00:23:43,119 --> 00:23:46,080
Speaker 1: than here on Earth. So in our Solar system, for example,

464
00:23:46,320 --> 00:23:49,040
Speaker 1: there's a massive producer of cosmic rays in the Sun.

465
00:23:49,400 --> 00:23:52,680
Speaker 1: It pumps out protons and electrons and photons and all

466
00:23:52,720 --> 00:23:55,239
Speaker 1: sorts of stuff, and when the protons and electrons hit

467
00:23:55,280 --> 00:23:58,960
Speaker 1: the Earth, we consider those cosmic rays. And Jupiter also

468
00:23:59,040 --> 00:24:01,919
Speaker 1: puts out a lot of radio contributes to cosmic rays.

469
00:24:02,240 --> 00:24:04,639
Speaker 1: The center of our galaxy is a massive source of

470
00:24:04,720 --> 00:24:07,560
Speaker 1: radiation because there's a lot of crazy stuff going on

471
00:24:07,640 --> 00:24:10,760
Speaker 1: in there. It's hot, it's dense, it's nasty. Things around

472
00:24:10,800 --> 00:24:13,919
Speaker 1: a black hole also emit cosmic rays because there's a

473
00:24:13,920 --> 00:24:16,480
Speaker 1: lot of energy there. And so basically a lot of

474
00:24:16,520 --> 00:24:19,320
Speaker 1: things in the universe are emitting cosmic rays and they

475
00:24:19,359 --> 00:24:22,159
Speaker 1: go from fairly low energy all the way up to

476
00:24:22,280 --> 00:24:26,080
Speaker 1: like the craziest highest energy things ever seen in the universe,

477
00:24:26,200 --> 00:24:29,560
Speaker 1: which are what which are created by things we don't know. So,

478
00:24:29,640 --> 00:24:31,600
Speaker 1: for example, the large hadron collide, which is like the

479
00:24:31,600 --> 00:24:35,640
Speaker 1: pinnacle of energy the humanity's ever created. We accelerate things

480
00:24:35,640 --> 00:24:39,480
Speaker 1: to have like thirteen terra electron bolts. That's thirteen trillion

481
00:24:39,560 --> 00:24:43,080
Speaker 1: electron bolts of energy. But out in space we see

482
00:24:43,080 --> 00:24:46,200
Speaker 1: things that have a million times as much energy. Whoa

483
00:24:46,280 --> 00:24:49,960
Speaker 1: yeah wow, And we don't know what causes that. Like

484
00:24:50,040 --> 00:24:52,040
Speaker 1: we know that the center of the galaxy emits some

485
00:24:52,320 --> 00:24:55,199
Speaker 1: but not that high energy. We know supernovas creates some

486
00:24:55,359 --> 00:24:57,640
Speaker 1: but not that high energy. We know if you take

487
00:24:57,680 --> 00:25:00,879
Speaker 1: particles from supernovas whiz them around um black hole, that

488
00:25:00,920 --> 00:25:03,080
Speaker 1: gives them a little bit more energy, but still not

489
00:25:03,240 --> 00:25:06,399
Speaker 1: that high energy. So we see these particles from space

490
00:25:06,720 --> 00:25:09,239
Speaker 1: that have crazy high energy, and nothing we know in

491
00:25:09,280 --> 00:25:12,399
Speaker 1: the universe can make particles that high energy. It's like

492
00:25:12,440 --> 00:25:15,760
Speaker 1: a huge mystery. Maybe it's a glitch in the simulation.

493
00:25:16,000 --> 00:25:20,040
Speaker 1: Maybe it's alien particle physicists shooting their beams at us.

494
00:25:20,240 --> 00:25:22,239
Speaker 1: Maybe there's information there we don't know.

495
00:25:22,720 --> 00:25:25,560
Speaker 2: Okay, go ahead and mark that spot on your dKu

496
00:25:25,640 --> 00:25:28,399
Speaker 2: Bingo cards. Friends, I knew that was coming.

497
00:25:28,840 --> 00:25:33,400
Speaker 1: Aliens, Yeah, yep. And so they impact life on Earth

498
00:25:33,440 --> 00:25:36,600
Speaker 1: here because they hit us, but they hit the atmosphere,

499
00:25:36,760 --> 00:25:39,399
Speaker 1: and the atmosphere is a great shield from cosmic rays.

500
00:25:39,520 --> 00:25:41,760
Speaker 1: But it doesn't just like delete them. What happens when

501
00:25:41,760 --> 00:25:43,879
Speaker 1: a particle hits the top of the atmosphere is it

502
00:25:43,920 --> 00:25:46,879
Speaker 1: collides into the particles in the atmosphere. And so you

503
00:25:46,960 --> 00:25:49,959
Speaker 1: go from having one very energetic particle to two that

504
00:25:50,000 --> 00:25:52,119
Speaker 1: have half as much energy, to four with a quarter

505
00:25:52,160 --> 00:25:55,359
Speaker 1: as much energy, to a trillions of particles, each with

506
00:25:55,440 --> 00:25:58,679
Speaker 1: a small slice of the energy, but still enough to

507
00:25:58,720 --> 00:26:00,399
Speaker 1: make it all the way down to the star of

508
00:26:00,400 --> 00:26:03,600
Speaker 1: the Earth. And so we have a constant flux of

509
00:26:03,640 --> 00:26:05,919
Speaker 1: cosmic rays on the surface of the Earth. It's like

510
00:26:06,080 --> 00:26:08,760
Speaker 1: one hundred and fifty muons per meter squared wow per

511
00:26:08,880 --> 00:26:12,439
Speaker 1: second at sea level. So like every fingernail you have

512
00:26:13,040 --> 00:26:16,880
Speaker 1: has hundreds of muons passing through it every second. They're everywhere.

513
00:26:17,240 --> 00:26:19,560
Speaker 2: So you know what I'm wondering, do I need to

514
00:26:19,600 --> 00:26:20,159
Speaker 2: worry about that?

515
00:26:22,320 --> 00:26:25,280
Speaker 1: Well, it contributes to you know, changes in your DNA

516
00:26:25,520 --> 00:26:29,160
Speaker 1: because cosmic grays carry energy and if they hit your DNA,

517
00:26:29,840 --> 00:26:33,840
Speaker 1: they can change essentially the information stored there in great

518
00:26:33,840 --> 00:26:36,760
Speaker 1: analogy to what happens when a cosmic gray hits a computer. Right,

519
00:26:37,240 --> 00:26:40,800
Speaker 1: this is how biology stores information, but it's not totally robust.

520
00:26:41,280 --> 00:26:43,119
Speaker 1: You know, I'm not an expert in biology, but my

521
00:26:43,200 --> 00:26:45,920
Speaker 1: understanding is that cosmic ray can like either hit the

522
00:26:46,000 --> 00:26:49,440
Speaker 1: DNA directly or it can ionize water, which makes free

523
00:26:49,520 --> 00:26:52,520
Speaker 1: radicals that react with the DNA. And in the end

524
00:26:52,600 --> 00:26:55,360
Speaker 1: you can have something which was originally like a cytosine

525
00:26:55,400 --> 00:26:58,080
Speaker 1: and now behaves like thiamine, and that gets read out

526
00:26:58,080 --> 00:27:01,280
Speaker 1: differently by your molecular machine. Now you're building a different

527
00:27:01,280 --> 00:27:04,760
Speaker 1: protein and like, oops, now you have cancer, or oops,

528
00:27:04,800 --> 00:27:07,399
Speaker 1: now you have like laser rays out of your eyeballs. Right,

529
00:27:07,560 --> 00:27:09,359
Speaker 1: all sorts of mutations, And so I think this is

530
00:27:09,359 --> 00:27:12,480
Speaker 1: a big part of our evolutionary history that cosmic creates

531
00:27:12,560 --> 00:27:16,639
Speaker 1: contribute to changes in our DNA. At least, it's my

532
00:27:16,720 --> 00:27:20,000
Speaker 1: favorite explanation for how me and Katrina have an athletic.

533
00:27:19,640 --> 00:27:23,239
Speaker 2: Sun Wait, wait, when I got skin cancer, you mean

534
00:27:23,320 --> 00:27:25,920
Speaker 2: I could have gotten lasers out of my eyes because

535
00:27:25,960 --> 00:27:29,320
Speaker 2: that would have been way cooler. Anyway, sunscreen and broad

536
00:27:29,400 --> 00:27:32,360
Speaker 2: rimmed hats are your friends friends.

537
00:27:31,960 --> 00:27:35,360
Speaker 1: Yes, exactly. And in that case, I think mostly skin

538
00:27:35,440 --> 00:27:38,679
Speaker 1: cancer is caused by ultraviolet radiation and not by like

539
00:27:38,800 --> 00:27:43,080
Speaker 1: more deeply penetrating muons or neutrinos. But it's the same principle,

540
00:27:43,160 --> 00:27:46,840
Speaker 1: you know, particles in that case, photons from space corrupting

541
00:27:46,880 --> 00:27:49,280
Speaker 1: the information. And so think of these things as just

542
00:27:49,359 --> 00:27:53,119
Speaker 1: high energy particles from space to come down through the atmosphere. Okay,

543
00:27:53,240 --> 00:27:55,040
Speaker 1: so you have these particles from space that carry a

544
00:27:55,040 --> 00:27:58,600
Speaker 1: lot of energy. Mostly it's muons. They're also electrons in there.

545
00:27:58,600 --> 00:28:01,679
Speaker 1: They don't penetrate as deeply. Most the electrons are blocked

546
00:28:01,720 --> 00:28:05,040
Speaker 1: by stuff like skin or you like a small sheet

547
00:28:05,080 --> 00:28:08,440
Speaker 1: of metal. Muons have more mass and so they don't

548
00:28:08,480 --> 00:28:11,000
Speaker 1: interact as much and so they can go deeper into

549
00:28:11,080 --> 00:28:14,720
Speaker 1: an object. They are also neutrons. Neutrons are created in

550
00:28:14,760 --> 00:28:17,480
Speaker 1: these showers, and because they're neutral, they pass through a

551
00:28:17,520 --> 00:28:21,280
Speaker 1: lot of material. They're penetrating as well. Neutrons are less common.

552
00:28:21,280 --> 00:28:24,480
Speaker 1: They're like one hundred times less dense than muons, but

553
00:28:24,600 --> 00:28:26,600
Speaker 1: they have a lot more mass to them, so they

554
00:28:26,600 --> 00:28:29,080
Speaker 1: can really do a lot more damage. So you have

555
00:28:29,119 --> 00:28:31,000
Speaker 1: these particles from space, and we told you that we

556
00:28:31,080 --> 00:28:35,000
Speaker 1: build all of our digital infrastructure out of semiconductors, which

557
00:28:35,040 --> 00:28:38,600
Speaker 1: rely on like the delicate balance between a conductor and

558
00:28:38,640 --> 00:28:42,600
Speaker 1: an insulator based on how exactly the electron bands are arranged,

559
00:28:42,640 --> 00:28:46,240
Speaker 1: and essentially build everything out of these building blocks. Well,

560
00:28:46,480 --> 00:28:50,080
Speaker 1: what happens when a cosmic ray passes through a lattice

561
00:28:50,120 --> 00:28:53,440
Speaker 1: of silicon. It can smash right into one of those atoms,

562
00:28:53,560 --> 00:28:56,640
Speaker 1: breaking up the nucleus, or it can push that atom,

563
00:28:57,160 --> 00:29:00,080
Speaker 1: or it can just ionize a bunch of silicon. The

564
00:29:00,120 --> 00:29:03,040
Speaker 1: silicon atoms that it kicked off can like flow through

565
00:29:03,080 --> 00:29:06,640
Speaker 1: the lattice, ionizing it. And so essentially, if you build

566
00:29:06,800 --> 00:29:09,920
Speaker 1: your whole digital infrastructure out of this stuff, it's like

567
00:29:10,000 --> 00:29:13,000
Speaker 1: taking a sharpie and just like scrawling a ride across

568
00:29:13,040 --> 00:29:13,760
Speaker 1: the page.

569
00:29:13,960 --> 00:29:16,600
Speaker 2: Okay, so it's not like it's so I'm thinking about

570
00:29:16,640 --> 00:29:19,000
Speaker 2: it as a highway now with cars moving along it,

571
00:29:19,080 --> 00:29:22,280
Speaker 2: the cars being the electrons and the silicon being the highway.

572
00:29:22,720 --> 00:29:25,480
Speaker 2: It's not that the cars are getting moved around. It's

573
00:29:25,480 --> 00:29:28,600
Speaker 2: that you're essentially like blowing up the highway and now

574
00:29:28,920 --> 00:29:31,520
Speaker 2: the cars like they don't know where to go anymore.

575
00:29:31,840 --> 00:29:34,800
Speaker 1: Yeah, essentially you're blowing up the highway. And think about

576
00:29:34,840 --> 00:29:38,080
Speaker 1: for example, your capacitor, right, your basic unit of memory

577
00:29:38,480 --> 00:29:41,600
Speaker 1: in your computer. What's going to happen if you suddenly

578
00:29:41,600 --> 00:29:44,440
Speaker 1: deposit a whole bunch of charge, or you like tear

579
00:29:44,520 --> 00:29:46,920
Speaker 1: through that and destroy the insulator so the charge leaks out.

580
00:29:47,160 --> 00:29:48,680
Speaker 1: You're going to go from a zero to a one,

581
00:29:48,880 --> 00:29:51,360
Speaker 1: or you're going to go from a one to a zero. Right,

582
00:29:51,760 --> 00:29:54,240
Speaker 1: You've built this careful thing out of these bricks and

583
00:29:54,240 --> 00:29:55,720
Speaker 1: then you have to suddenly just tear right through it,

584
00:29:55,760 --> 00:29:58,000
Speaker 1: and you still have the machinery around it that's going

585
00:29:58,040 --> 00:30:00,640
Speaker 1: to try to interpret what's going on the one or

586
00:30:00,680 --> 00:30:04,400
Speaker 1: a zero. Right, Your transistor that's next to the conductor

587
00:30:04,400 --> 00:30:06,720
Speaker 1: is gonna be like, oh, excuse me, by the way,

588
00:30:06,800 --> 00:30:09,000
Speaker 1: this doesn't seem to be like it's behaving itself. It's

589
00:30:09,040 --> 00:30:11,720
Speaker 1: just gonna be like, is there charge zero? Is there

590
00:30:11,760 --> 00:30:12,680
Speaker 1: no charge one?

591
00:30:13,200 --> 00:30:13,960
Speaker 2: That sounds bad?

592
00:30:14,360 --> 00:30:16,840
Speaker 1: Yeah, And the same is true for your s RAM

593
00:30:16,880 --> 00:30:19,320
Speaker 1: for example. This was built out of knot gates, and

594
00:30:19,360 --> 00:30:22,960
Speaker 1: these again are built out of transistors, and transistors have

595
00:30:23,200 --> 00:30:25,680
Speaker 1: various components of silicon that are dope in various ways

596
00:30:25,680 --> 00:30:27,840
Speaker 1: so they can do their logic. If you have a

597
00:30:27,840 --> 00:30:30,200
Speaker 1: cosmic ray plow through that, it's going to deposit a

598
00:30:30,200 --> 00:30:31,960
Speaker 1: bunch of charge. It's going to change the way those

599
00:30:32,000 --> 00:30:35,640
Speaker 1: gates operate in the same way. Now, hard drives, which

600
00:30:35,680 --> 00:30:39,040
Speaker 1: are the most robust and the most difficult to change,

601
00:30:39,120 --> 00:30:43,080
Speaker 1: have that like insulated box. So this requires like stronger radiation.

602
00:30:43,520 --> 00:30:45,760
Speaker 1: But essentially you want to have like charge in there

603
00:30:45,880 --> 00:30:47,880
Speaker 1: or not charge in there. If you have a cosmic

604
00:30:47,960 --> 00:30:49,680
Speaker 1: ray that comes in and tears through it and essentially

605
00:30:49,760 --> 00:30:52,280
Speaker 1: deposits a bunch of charge, you're gonna go from a

606
00:30:52,360 --> 00:30:55,080
Speaker 1: zero to a one. Or if it breaks the containment

607
00:30:55,120 --> 00:30:57,200
Speaker 1: and lets the charge out, then you're gonna go from

608
00:30:57,200 --> 00:31:00,280
Speaker 1: a one to a zero. So it's possible for every

609
00:31:00,280 --> 00:31:03,680
Speaker 1: one of these components in your computer to be susceptible

610
00:31:03,680 --> 00:31:06,600
Speaker 1: to cause and graze, very similar to how it happens

611
00:31:06,600 --> 00:31:07,160
Speaker 1: with DNA.

612
00:31:07,640 --> 00:31:11,520
Speaker 2: Okay, so that all sounds bad, but can we get

613
00:31:11,520 --> 00:31:13,959
Speaker 2: a little bit more concrete about, Like does that mean

614
00:31:14,000 --> 00:31:16,680
Speaker 2: your computer is just gonna like one hundred percent crash

615
00:31:16,760 --> 00:31:19,720
Speaker 2: every time this happens, or like what's the range of

616
00:31:19,760 --> 00:31:20,440
Speaker 2: outcomes here?

617
00:31:21,000 --> 00:31:24,120
Speaker 1: So it depends on where it hits, right, it might

618
00:31:24,240 --> 00:31:26,320
Speaker 1: hit your computer and it just hits a place where

619
00:31:26,360 --> 00:31:28,840
Speaker 1: like nothing is being used anyway, Like you have an

620
00:31:28,840 --> 00:31:30,800
Speaker 1: empty part of your hard drive and it goes from

621
00:31:30,920 --> 00:31:33,440
Speaker 1: zero to one. Whatever it was noise, it doesn't really matter.

622
00:31:33,960 --> 00:31:35,840
Speaker 1: Or maybe you were about to store a picture of

623
00:31:35,840 --> 00:31:38,320
Speaker 1: your puppy there and so it goes from zero to

624
00:31:38,360 --> 00:31:41,440
Speaker 1: one and then you overwrite your puppy on top of it,

625
00:31:41,520 --> 00:31:44,160
Speaker 1: so it doesn't matter. Right, So those are the best

626
00:31:44,160 --> 00:31:47,480
Speaker 1: case scenarios. You've overwritten your garbage with a puppy.

627
00:31:47,760 --> 00:31:49,920
Speaker 2: Oh good, I thought you were gonna say, overrode my puppy,

628
00:31:49,920 --> 00:31:51,520
Speaker 2: and I was gonna get really upset.

629
00:31:52,520 --> 00:31:53,480
Speaker 1: No, that's a disaster.

630
00:31:53,680 --> 00:31:54,840
Speaker 2: Yeah, meal is very cute.

631
00:31:54,960 --> 00:31:57,560
Speaker 1: Yeah. So in the sort of next stage of like

632
00:31:57,800 --> 00:32:01,480
Speaker 1: problematic thing, it's like something goes wrong and it's crucial

633
00:32:01,480 --> 00:32:05,000
Speaker 1: and your computer crashes. You know, like your computer follows

634
00:32:05,000 --> 00:32:07,680
Speaker 1: some instruction in its memory and the instruction isn't what

635
00:32:07,720 --> 00:32:09,560
Speaker 1: it was supposed to be because it got changed by

636
00:32:09,600 --> 00:32:12,200
Speaker 1: a cosmic ray and it does this instead of doing that,

637
00:32:12,520 --> 00:32:14,680
Speaker 1: and it doesn't work and it gets stuck and boom,

638
00:32:14,720 --> 00:32:18,440
Speaker 1: your computer has crashed. That's actually a good outcome because

639
00:32:18,560 --> 00:32:20,680
Speaker 1: you notice it and it stops you from using it,

640
00:32:20,720 --> 00:32:23,280
Speaker 1: and then you like restart your computer and you're.

641
00:32:23,160 --> 00:32:25,680
Speaker 2: Fine, so your computer can recover.

642
00:32:25,800 --> 00:32:28,840
Speaker 1: Yeah, if your computer crashes, you just reboot it, right,

643
00:32:29,000 --> 00:32:31,160
Speaker 1: Like it happens all the time, especially if you use Windows.

644
00:32:32,080 --> 00:32:36,080
Speaker 2: Oh ouch, but isn't your silicon chip still like toast

645
00:32:36,160 --> 00:32:36,920
Speaker 2: because it got hit.

646
00:32:37,200 --> 00:32:39,320
Speaker 1: No, No, you could just refresh. It's like it will

647
00:32:39,360 --> 00:32:41,520
Speaker 1: change it from zero to one. But it's not like

648
00:32:41,560 --> 00:32:44,719
Speaker 1: it's destroyed it, right, Okay. Usually these things, you know,

649
00:32:44,760 --> 00:32:48,040
Speaker 1: are robust. It's about the charge that's stored in that circuit,

650
00:32:48,400 --> 00:32:50,800
Speaker 1: and so they can like release it or right into

651
00:32:50,840 --> 00:32:53,920
Speaker 1: it accidentally. But you restart all this stuff, You're gonna

652
00:32:53,920 --> 00:32:56,880
Speaker 1: be fine. It's not permanent damage. If it happens occasionally.

653
00:32:56,960 --> 00:32:59,320
Speaker 1: We'll talk later about what happens to electronics inside the

654
00:32:59,360 --> 00:33:01,760
Speaker 1: large hadron lighter and why that needs to be much

655
00:33:01,800 --> 00:33:04,520
Speaker 1: more radiation hard. But you know, if it happens once

656
00:33:04,600 --> 00:33:06,680
Speaker 1: or twice, you're fine. You have like enough silicon there

657
00:33:06,680 --> 00:33:07,760
Speaker 1: for these things to still work.

658
00:33:07,880 --> 00:33:10,240
Speaker 2: Okay, So then what is a bad result.

659
00:33:10,480 --> 00:33:13,479
Speaker 1: The bad result is when it happens silently, like you

660
00:33:13,520 --> 00:33:16,600
Speaker 1: have stored some data on your computer and the bit

661
00:33:16,720 --> 00:33:19,440
Speaker 1: gets flipped and you don't notice, and later you read

662
00:33:19,480 --> 00:33:21,800
Speaker 1: that in you do some analysis and you're like maybe

663
00:33:21,840 --> 00:33:24,560
Speaker 1: you're doing some science or you know, your puppy's eye

664
00:33:24,680 --> 00:33:28,600
Speaker 1: color has changed or something. And this is when it's dangerous,

665
00:33:28,600 --> 00:33:32,560
Speaker 1: when it's a silent mistake. Right. Or for example, you're

666
00:33:32,600 --> 00:33:37,080
Speaker 1: storing voting results from some precinct in Virginia and like, oops,

667
00:33:37,080 --> 00:33:40,520
Speaker 1: a bit flips and somebody now has more or fewer votes. Right,

668
00:33:40,800 --> 00:33:43,320
Speaker 1: This is when we really rely on this stuff. So

669
00:33:43,680 --> 00:33:46,520
Speaker 1: not knowing that it's happened and having it happen silently

670
00:33:46,560 --> 00:33:49,280
Speaker 1: in a way that doesn't cause any errors, that's the

671
00:33:49,280 --> 00:33:50,240
Speaker 1: worst case scenario.

672
00:33:50,480 --> 00:33:53,960
Speaker 2: Okay, this is getting scary. How often does this happen?

673
00:33:54,400 --> 00:33:56,800
Speaker 1: So there's bad news and then there's good news. Okay,

674
00:33:57,000 --> 00:34:00,280
Speaker 1: So bad news is that it's not that rare, you know,

675
00:34:00,320 --> 00:34:04,200
Speaker 1: because there are cosmic rays everywhere, So you should expect

676
00:34:04,280 --> 00:34:09,160
Speaker 1: like a few bit flips per year per gigabyte of RAM, right,

677
00:34:09,239 --> 00:34:12,080
Speaker 1: and I have like thirty gigabytes of RAM on my computer,

678
00:34:12,520 --> 00:34:15,600
Speaker 1: and so I'm expecting like dozens of times a year

679
00:34:16,200 --> 00:34:18,000
Speaker 1: a bit it's going to be flipped in my RAM.

680
00:34:18,200 --> 00:34:20,920
Speaker 1: Oh yikes, exactly, And so that seems like an issue.

681
00:34:21,200 --> 00:34:23,920
Speaker 1: But of course the nerds know this and they have

682
00:34:23,920 --> 00:34:26,520
Speaker 1: built protection for us. And sound like we're just running

683
00:34:26,520 --> 00:34:29,279
Speaker 1: out there totally exposed. If you have a computer in

684
00:34:29,320 --> 00:34:32,080
Speaker 1: an environment where you absolutely need it to be robust,

685
00:34:32,239 --> 00:34:35,319
Speaker 1: then there are clever systems to detect these errors and

686
00:34:35,520 --> 00:34:36,200
Speaker 1: correct them.

687
00:34:36,600 --> 00:34:39,440
Speaker 2: I find myself wondering, was there an era when we

688
00:34:39,560 --> 00:34:43,399
Speaker 2: had computers but we didn't know this and there were

689
00:34:43,440 --> 00:34:45,319
Speaker 2: like disasters because we didn't know this.

690
00:34:45,920 --> 00:34:48,680
Speaker 1: Yeah. One of the ways this was originally discovered is

691
00:34:49,239 --> 00:34:54,480
Speaker 1: that electronics near nuclear testing in the fifties had anomalies.

692
00:34:54,480 --> 00:34:56,640
Speaker 1: People were like, whoa, what's going on with our electronics?

693
00:34:57,040 --> 00:34:59,439
Speaker 1: And then they realized, of course that the radiation from

694
00:34:59,440 --> 00:35:03,040
Speaker 1: the blast was interfering with the electronics. It was like

695
00:35:03,120 --> 00:35:06,480
Speaker 1: in the seventies that the detailed physics involved was understood

696
00:35:06,520 --> 00:35:09,800
Speaker 1: and like demonstrated in particle beams, and so it was

697
00:35:09,840 --> 00:35:12,879
Speaker 1: really like in the eighties people understood what's going on here,

698
00:35:12,960 --> 00:35:14,080
Speaker 1: and can we build protection?

699
00:35:14,480 --> 00:35:17,080
Speaker 2: Oh wow? Okay, well I'm glad we've got protection now,

700
00:35:17,320 --> 00:35:19,279
Speaker 2: all right, So tell me how the protection works, please.

701
00:35:19,320 --> 00:35:21,760
Speaker 1: So the simplest and the most expensive way to protect

702
00:35:21,800 --> 00:35:24,880
Speaker 1: your data is just to have copies of it, right, Like,

703
00:35:24,880 --> 00:35:27,160
Speaker 1: if you have really sensitive data stored on a hard drive.

704
00:35:27,360 --> 00:35:29,520
Speaker 1: Hard drives used to be much less stable. You could

705
00:35:29,520 --> 00:35:31,640
Speaker 1: just like lose a drive, like the head dropped on it.

706
00:35:31,680 --> 00:35:34,440
Speaker 1: Back when there were magnetic spinning discs, and so we

707
00:35:34,480 --> 00:35:36,480
Speaker 1: had these things called like raidar rays where you just

708
00:35:36,520 --> 00:35:39,160
Speaker 1: had like everything was stored in duplicate or in triplicate

709
00:35:39,280 --> 00:35:42,319
Speaker 1: even and in triplicate is cool because if one of

710
00:35:42,320 --> 00:35:45,279
Speaker 1: them gets corrupted, you have two other copies, and so

711
00:35:45,320 --> 00:35:47,080
Speaker 1: you can vote. You're like, is this bit supposed to

712
00:35:47,120 --> 00:35:49,400
Speaker 1: be a zero or a one? And if two of

713
00:35:49,440 --> 00:35:51,920
Speaker 1: them agree, then you know, then that's the way you go.

714
00:35:52,040 --> 00:35:54,000
Speaker 1: I think that's how like the flight systems work on

715
00:35:54,040 --> 00:35:57,200
Speaker 1: the Space Shuttle, right, they all vote, the three independent

716
00:35:57,239 --> 00:36:00,120
Speaker 1: systems or something like that, and they all vote, so

717
00:36:00,160 --> 00:36:02,520
Speaker 1: the you always have two the degree. So that's the

718
00:36:02,560 --> 00:36:05,600
Speaker 1: most complicated and expensive way. And that's quite expensive because

719
00:36:05,640 --> 00:36:08,600
Speaker 1: now you're like tripling the cost of your memory. If

720
00:36:08,640 --> 00:36:10,319
Speaker 1: you want to store a gigabyte, you really have to

721
00:36:10,360 --> 00:36:13,239
Speaker 1: have three gigabytes of memory in there just to make

722
00:36:13,280 --> 00:36:16,799
Speaker 1: it protected, Yanks. And so since that's so expensive, people

723
00:36:16,880 --> 00:36:20,920
Speaker 1: came up with cheaper, faster, more clever ways, things like checksums. Right,

724
00:36:20,960 --> 00:36:23,160
Speaker 1: Like if you send a message across the internet and

725
00:36:23,200 --> 00:36:25,680
Speaker 1: you want to make sure the message arrived uncorrupted, then

726
00:36:25,719 --> 00:36:28,239
Speaker 1: none of it got like garbled along the way. You

727
00:36:28,280 --> 00:36:30,840
Speaker 1: can also send a checksum, which is like the output

728
00:36:31,040 --> 00:36:34,040
Speaker 1: of a little calculation you do on the data. As

729
00:36:34,040 --> 00:36:35,799
Speaker 1: simple way to think of a checksums to be like

730
00:36:35,960 --> 00:36:37,919
Speaker 1: take the whole data set and treat it like a number.

731
00:36:38,080 --> 00:36:41,000
Speaker 1: Was it even or odd? And that way, if I

732
00:36:41,040 --> 00:36:43,319
Speaker 1: send you a message, and I also send you by

733
00:36:43,320 --> 00:36:44,920
Speaker 1: the way it should have been even, then you can

734
00:36:45,000 --> 00:36:47,120
Speaker 1: check to make sure it's even. That doesn't catch all

735
00:36:47,200 --> 00:36:50,440
Speaker 1: possible errors, like if you flip two bits, for example,

736
00:36:50,680 --> 00:36:52,600
Speaker 1: But it's one simple way to say, like were there

737
00:36:52,640 --> 00:36:56,839
Speaker 1: any mistakes? So in modern computers they do something which

738
00:36:56,880 --> 00:36:59,120
Speaker 1: is more sophisticated than just a simple like is it

739
00:36:59,160 --> 00:37:02,600
Speaker 1: even or odd? They have these parody checkers that take

740
00:37:02,719 --> 00:37:05,600
Speaker 1: like groups of four data words. A word is like

741
00:37:05,640 --> 00:37:08,479
Speaker 1: a bunch of bits altogether. And you have parity bits

742
00:37:08,480 --> 00:37:10,719
Speaker 1: which check how many events there are and how many

743
00:37:10,719 --> 00:37:12,960
Speaker 1: odds there are. And if you overlap these things in

744
00:37:13,000 --> 00:37:16,000
Speaker 1: a clever way, and you have this voting system, you

745
00:37:16,000 --> 00:37:18,799
Speaker 1: can have like one parody bit checks three words and

746
00:37:18,840 --> 00:37:22,399
Speaker 1: another parody bit checks three other words. And so through

747
00:37:22,440 --> 00:37:25,640
Speaker 1: some clever algorithms and clever math, you can detect any

748
00:37:25,680 --> 00:37:30,480
Speaker 1: bitflip in any of those words without having complete duplicates.

749
00:37:30,920 --> 00:37:32,799
Speaker 1: So this is like ten percent of the data cost.

750
00:37:32,880 --> 00:37:35,440
Speaker 1: You have a gigabyte of memory, you build a gigabyte

751
00:37:35,520 --> 00:37:38,600
Speaker 1: plus ten percent, and you have enough data storage to

752
00:37:38,680 --> 00:37:42,359
Speaker 1: detect if there were any bits flipped in your core gigabyte.

753
00:37:42,400 --> 00:37:45,399
Speaker 2: But we didn't have this clever and cheap version during

754
00:37:45,440 --> 00:37:48,360
Speaker 2: the Shuttle era, and that's why the Shuttle was so expensive.

755
00:37:50,480 --> 00:37:53,359
Speaker 1: I don't know if the memory costs contributed a lot

756
00:37:53,480 --> 00:37:57,480
Speaker 1: to the Shuttle. And many computer systems have this already.

757
00:37:58,200 --> 00:38:02,000
Speaker 1: So for example, your hard drive very likely has error

758
00:38:02,040 --> 00:38:05,480
Speaker 1: correction on it. Your RAM probably has error correction on it.

759
00:38:05,760 --> 00:38:08,920
Speaker 1: CPU caches usually do not, because this is the s

760
00:38:09,000 --> 00:38:11,400
Speaker 1: RAM stuff because it has to be super duper fast.

761
00:38:11,400 --> 00:38:13,320
Speaker 1: It really will slow down your computer if you have

762
00:38:13,480 --> 00:38:16,279
Speaker 1: error correction on that CPU, like the worksheet that the

763
00:38:16,320 --> 00:38:20,120
Speaker 1: CPU is using. But if you have a really important computers,

764
00:38:20,200 --> 00:38:22,640
Speaker 1: like you're operating a data center and you need to

765
00:38:22,640 --> 00:38:26,760
Speaker 1: provide really robust calculations for your consumers, or you're running

766
00:38:26,760 --> 00:38:29,760
Speaker 1: something in space, then you need to have error correction

767
00:38:30,160 --> 00:38:33,000
Speaker 1: on your caches as well. Although I was reading that

768
00:38:33,120 --> 00:38:37,960
Speaker 1: often in space applications they take consumer PCs and they

769
00:38:38,040 --> 00:38:40,840
Speaker 1: just turn off the CPU cache because they'd rather be

770
00:38:41,000 --> 00:38:44,000
Speaker 1: robust than fast, and so they're like, this part is

771
00:38:44,040 --> 00:38:46,160
Speaker 1: not robust in space, so let's just turn it off.

772
00:38:46,640 --> 00:38:48,160
Speaker 2: All right, Well, let's take a break, and when we

773
00:38:48,200 --> 00:38:50,919
Speaker 2: get back, Kelly will tell a fun story about how

774
00:38:51,040 --> 00:39:13,120
Speaker 2: galactic cosmic rays messed up computers in space. All right,

775
00:39:13,400 --> 00:39:17,400
Speaker 2: we're back. We're on the International Space Station and an

776
00:39:17,440 --> 00:39:22,640
Speaker 2: alarm has just gone off. Samantha Christafaretti, who's an Italian astronaut,

777
00:39:23,320 --> 00:39:26,080
Speaker 2: was amazing at her ability to memorize all of the

778
00:39:26,239 --> 00:39:28,239
Speaker 2: different alarms on the station. And even though this is

779
00:39:28,280 --> 00:39:30,520
Speaker 2: the first time she's ever heard this alarm, she immediately

780
00:39:30,560 --> 00:39:33,960
Speaker 2: knows what it is and she yells ammonia leak. And

781
00:39:34,080 --> 00:39:37,799
Speaker 2: so she and Terry Vertz have memorized the protocol for

782
00:39:37,880 --> 00:39:41,080
Speaker 2: ammonia leaks. And so what they do is they run

783
00:39:41,160 --> 00:39:44,360
Speaker 2: over towards the Russian segment and they close the airlock

784
00:39:44,440 --> 00:39:47,120
Speaker 2: for the American side. And so what happens if there's

785
00:39:47,160 --> 00:39:51,239
Speaker 2: an ammonia leak is that the coolant system for keeping

786
00:39:51,239 --> 00:39:54,840
Speaker 2: the American side of the International Space Station is leaking.

787
00:39:54,920 --> 00:39:58,120
Speaker 2: So ammonia is toxic and so they can't stay over

788
00:39:58,160 --> 00:40:00,799
Speaker 2: there anymore, So they close off their side so that

789
00:40:00,840 --> 00:40:04,000
Speaker 2: the toxic stuff can't get out. Then they're supposed to

790
00:40:04,000 --> 00:40:07,319
Speaker 2: get naked. Then they're supposed to go through to the

791
00:40:07,400 --> 00:40:11,240
Speaker 2: Russian side, and then they're supposed to close the hatch

792
00:40:11,440 --> 00:40:14,400
Speaker 2: and hope that the Russians have extra undies. And I

793
00:40:14,440 --> 00:40:18,280
Speaker 2: saw Daniel look confused, and so, Daniel, are you wondering

794
00:40:19,560 --> 00:40:21,160
Speaker 2: why they closed to the second hatch.

795
00:40:21,360 --> 00:40:24,359
Speaker 1: Why did they close the second hatch, Kelly, just to.

796
00:40:24,280 --> 00:40:25,719
Speaker 2: Make sure they didn't get any more moonia on the

797
00:40:25,760 --> 00:40:28,239
Speaker 2: other side. But you're probably wondering actually why they were

798
00:40:28,239 --> 00:40:29,160
Speaker 2: supposed to get naked.

799
00:40:29,040 --> 00:40:32,040
Speaker 1: Right, yes, exactly. I was having fun imagining it though.

800
00:40:32,400 --> 00:40:35,920
Speaker 2: Okay, well, they apparently were not having fun imagining what

801
00:40:35,960 --> 00:40:38,600
Speaker 2: it would be like because they skipped that step. But

802
00:40:38,640 --> 00:40:40,440
Speaker 2: they were supposed to take the clothes off because the

803
00:40:40,480 --> 00:40:44,160
Speaker 2: concern was ammonia might stick to their clothes and they

804
00:40:44,200 --> 00:40:47,400
Speaker 2: might end up bringing ammonia over to the Russian side.

805
00:40:47,880 --> 00:40:51,320
Speaker 2: And the Russians use Glai call to cool their side

806
00:40:51,320 --> 00:40:53,440
Speaker 2: of the International Space Station so they don't have this

807
00:40:53,560 --> 00:40:54,400
Speaker 2: toxic stuff.

808
00:40:54,480 --> 00:40:56,960
Speaker 1: So ammonia sticks to close but not to like skin.

809
00:40:57,280 --> 00:40:57,600
Speaker 1: I mean it.

810
00:40:57,640 --> 00:41:00,600
Speaker 2: Probably it could stick to everything, but the goal is

811
00:41:00,680 --> 00:41:03,600
Speaker 2: to bring as little as possible over to the Russian side.

812
00:41:03,680 --> 00:41:05,880
Speaker 1: Do you ever think the engineers are just like, let's

813
00:41:05,880 --> 00:41:07,799
Speaker 1: add getting naked to this protocol and see if the

814
00:41:07,800 --> 00:41:08,880
Speaker 1: astronauts will really do it.

815
00:41:08,960 --> 00:41:12,319
Speaker 2: Yeah, well, so you know, you've got to imagine that

816
00:41:12,360 --> 00:41:14,680
Speaker 2: at some point they were like, do I really want

817
00:41:14,719 --> 00:41:19,000
Speaker 2: to see my middle aged colleague naked and zero gravity?

818
00:41:18,719 --> 00:41:22,279
Speaker 2: And I think, and they must have both decided no,

819
00:41:22,880 --> 00:41:27,240
Speaker 2: And so they went over to the Russian side fully dressed.

820
00:41:27,280 --> 00:41:30,240
Speaker 2: They locked the second airlock, and then they got permission

821
00:41:30,280 --> 00:41:33,480
Speaker 2: to go back, and so they go back, and the

822
00:41:33,560 --> 00:41:36,360
Speaker 2: alarm goes off again, and they go through the whole

823
00:41:36,360 --> 00:41:38,759
Speaker 2: process the second time, and yet again they decide to

824
00:41:38,800 --> 00:41:41,680
Speaker 2: not take their clothes off. And I believe they ended

825
00:41:41,719 --> 00:41:43,560
Speaker 2: up saying they decided to not take their clothes off

826
00:41:43,560 --> 00:41:46,600
Speaker 2: because they couldn't smell ammonia. Ammonia has this like distinct

827
00:41:46,640 --> 00:41:49,480
Speaker 2: rotten egg smell. And it turned out that they were right.

828
00:41:49,560 --> 00:41:50,880
Speaker 2: It was a false alarm.

829
00:41:51,320 --> 00:41:53,040
Speaker 1: Was this the universe trying to get them naked? Is

830
00:41:53,040 --> 00:41:53,760
Speaker 1: that what was happening?

831
00:41:53,880 --> 00:41:57,000
Speaker 2: It could be, could be, But the best guess that

832
00:41:57,040 --> 00:42:00,080
Speaker 2: folks came up with afterwards for what happened is that

833
00:42:00,160 --> 00:42:05,040
Speaker 2: galactic cosmic radiation had hit their computers and had inadvertently

834
00:42:05,080 --> 00:42:08,040
Speaker 2: turned on the ammonia leak alarm, and there wasn't actually

835
00:42:08,080 --> 00:42:09,920
Speaker 2: an ammonia leak. They never were able to find an

836
00:42:09,920 --> 00:42:12,640
Speaker 2: ammonia leak, but it, you know, they started doing this

837
00:42:12,719 --> 00:42:15,200
Speaker 2: emergency protocol and they had to eventually do it twice

838
00:42:15,239 --> 00:42:18,279
Speaker 2: before they were able to fix their computers. Well, so

839
00:42:18,320 --> 00:42:20,680
Speaker 2: we're sort of talking about these data centers today, and

840
00:42:20,680 --> 00:42:22,160
Speaker 2: I guess one thing I want to point out is

841
00:42:22,160 --> 00:42:25,680
Speaker 2: that even though the International Space Station is to a

842
00:42:25,760 --> 00:42:30,279
Speaker 2: large extent protected by Earth's strong magnetosphere, which sends a

843
00:42:30,320 --> 00:42:33,480
Speaker 2: lot of these charge particles, you know, to the poles

844
00:42:33,520 --> 00:42:36,200
Speaker 2: and protects the International Space Station and the equipment and

845
00:42:36,239 --> 00:42:39,600
Speaker 2: people within it, you still get hit sometimes, and so

846
00:42:39,640 --> 00:42:41,520
Speaker 2: you still have to worry about the equipment. Where are

847
00:42:41,560 --> 00:42:44,440
Speaker 2: people thinking of putting these data centers? Are they within

848
00:42:44,520 --> 00:42:46,799
Speaker 2: the protection of the magnetic field or out past it?

849
00:42:46,960 --> 00:42:49,240
Speaker 1: I don't think they want to go very far because

850
00:42:49,239 --> 00:42:50,880
Speaker 1: the further you go, the harder it is to access

851
00:42:50,920 --> 00:42:53,440
Speaker 1: and to repair. And I'm not on record is thinking

852
00:42:53,440 --> 00:42:56,120
Speaker 1: that any of this is a good idea, and you know,

853
00:42:56,160 --> 00:42:58,719
Speaker 1: the cooling is are the radiation is tricky because you

854
00:42:58,719 --> 00:43:00,680
Speaker 1: don't have the benefit of the Earth's sphere, even if

855
00:43:00,719 --> 00:43:03,520
Speaker 1: you still have some of the magnetosphere. And so I

856
00:43:03,520 --> 00:43:07,160
Speaker 1: think it's a crazy idea pushed by tech bros who

857
00:43:07,160 --> 00:43:10,120
Speaker 1: think it's gonna be fun and sci fi. And you know,

858
00:43:10,200 --> 00:43:11,800
Speaker 1: I don't know about that. We'll have a whole another

859
00:43:11,800 --> 00:43:15,280
Speaker 1: episode digging into the economics of data centers in space.

860
00:43:15,680 --> 00:43:18,480
Speaker 1: But yeah, out there in space there is more radiation,

861
00:43:19,040 --> 00:43:22,920
Speaker 1: and so you need more protection and you need like

862
00:43:23,200 --> 00:43:25,560
Speaker 1: shielding for these things, or you need to make extra

863
00:43:25,680 --> 00:43:28,640
Speaker 1: error correction, or you need to use technologies that are

864
00:43:28,640 --> 00:43:33,320
Speaker 1: more radiation hard it actually on Earth. Sometimes I'm frustrated

865
00:43:33,320 --> 00:43:36,280
Speaker 1: by the amount of error correction. There are scenarios where

866
00:43:36,600 --> 00:43:39,240
Speaker 1: it would be better for physics, even if it's worse

867
00:43:39,400 --> 00:43:42,919
Speaker 1: for computers and for Amazon or whatever, to have less

868
00:43:43,040 --> 00:43:46,239
Speaker 1: error correction. Because all of these things are evidence of

869
00:43:46,280 --> 00:43:49,160
Speaker 1: cosmic rays. And if you're curious about cosmic rays, where

870
00:43:49,160 --> 00:43:51,279
Speaker 1: do they hit, what's going on? Then one of the

871
00:43:51,280 --> 00:43:54,800
Speaker 1: biggest challenge is seeing them. The really high energy cosmic

872
00:43:54,800 --> 00:43:58,040
Speaker 1: grays are really rare. It's like one per square kilometer

873
00:43:58,120 --> 00:44:01,560
Speaker 1: per century, either in a lot of square kilometers or

874
00:44:01,600 --> 00:44:04,440
Speaker 1: a lot of centuries. And these massive data centers that

875
00:44:04,480 --> 00:44:07,640
Speaker 1: are being built out are basically huge cosmic ray detectors.

876
00:44:08,000 --> 00:44:10,200
Speaker 1: And imagine if you could use all of Google and

877
00:44:10,239 --> 00:44:13,799
Speaker 1: Amazon's data centers to observe cosmic rays from space. It

878
00:44:13,800 --> 00:44:16,440
Speaker 1: would be incredible, right. I actually looked into this and

879
00:44:16,480 --> 00:44:18,439
Speaker 1: connected with folks at Google to see if we could

880
00:44:18,520 --> 00:44:21,319
Speaker 1: use it. But their air correction is so good they

881
00:44:21,320 --> 00:44:23,200
Speaker 1: don't even store it. They don't log it, and be like,

882
00:44:23,239 --> 00:44:24,560
Speaker 1: by the way, we flipped a bit here and we

883
00:44:24,640 --> 00:44:26,879
Speaker 1: corrected it, They just correct it and move on.

884
00:44:28,120 --> 00:44:30,120
Speaker 2: How hard would it be for them to collect that data?

885
00:44:30,440 --> 00:44:32,920
Speaker 1: Oh? Man, it would require a change in pretty low

886
00:44:33,000 --> 00:44:36,719
Speaker 1: level operating system stuff, unfortunately. And you know, for a

887
00:44:36,760 --> 00:44:38,480
Speaker 1: while they were going to be willing to share the

888
00:44:38,560 --> 00:44:40,719
Speaker 1: data with us if it was like something they already had,

889
00:44:40,840 --> 00:44:42,600
Speaker 1: they could just ship to us and we could analyze it.

890
00:44:42,640 --> 00:44:44,960
Speaker 1: And that was so excited. But then it turns out

891
00:44:45,120 --> 00:44:47,719
Speaker 1: it's not storage and getting them to do anything just

892
00:44:47,760 --> 00:44:50,120
Speaker 1: for fundamental physics is frustratingly difficult.

893
00:44:50,600 --> 00:44:52,320
Speaker 2: Google. I thought you were trying to not be evil

894
00:44:52,400 --> 00:44:54,000
Speaker 2: or did they like do away with that a long

895
00:44:54,040 --> 00:44:54,439
Speaker 2: time ago.

896
00:44:54,719 --> 00:44:56,880
Speaker 1: Yeah, I don't know. I mean, it's not their obligation

897
00:44:56,920 --> 00:44:59,839
Speaker 1: to fund basic research. But it's frustrating to me because

898
00:44:59,880 --> 00:45:03,399
Speaker 1: it means that these cosmic grays are there and they're

899
00:45:03,560 --> 00:45:07,160
Speaker 1: actually observed by our technology, and then that information is

900
00:45:07,600 --> 00:45:11,480
Speaker 1: just thrown away. You know, one person's error is another

901
00:45:11,480 --> 00:45:16,920
Speaker 1: person's gold maybe Nobel Prize gold. Right, So that's frustrating.

902
00:45:17,200 --> 00:45:19,800
Speaker 1: But there are other times when we think cosmic grays

903
00:45:19,920 --> 00:45:22,920
Speaker 1: could have affected things on Earth. The voting example I

904
00:45:22,960 --> 00:45:25,960
Speaker 1: mentioned earlier was not a hypothetical. There was an election

905
00:45:26,080 --> 00:45:29,480
Speaker 1: in two thousand and three in Brussels where one candidate

906
00:45:29,520 --> 00:45:32,040
Speaker 1: had a number of votes that was suspiciously off by

907
00:45:32,200 --> 00:45:35,600
Speaker 1: four ninety six. They're like, that's a weird number, Like,

908
00:45:35,640 --> 00:45:38,200
Speaker 1: how did this number just appear in the computers? It's

909
00:45:38,239 --> 00:45:41,879
Speaker 1: off by this specific power of two, right, fenty ninety

910
00:45:41,920 --> 00:45:43,880
Speaker 1: six is the power of two, So it could be

911
00:45:43,920 --> 00:45:46,759
Speaker 1: caused by a single bitflip. And you know they went

912
00:45:46,760 --> 00:45:48,960
Speaker 1: through and nobody tinkered with it. There's no evidence that

913
00:45:49,040 --> 00:45:51,800
Speaker 1: anybody like infected it or hacked it, or there was

914
00:45:51,840 --> 00:45:55,160
Speaker 1: a copyer or anything. They think probably was a bitflip

915
00:45:55,200 --> 00:45:59,200
Speaker 1: that caused this weird result in an election in Brussels,

916
00:45:59,239 --> 00:46:01,719
Speaker 1: and so it's certainly happened, right, It's something we need

917
00:46:01,760 --> 00:46:03,560
Speaker 1: to be aware of. I mean we need to know about.

918
00:46:03,800 --> 00:46:05,440
Speaker 2: Did it change the results of the election?

919
00:46:05,600 --> 00:46:07,200
Speaker 1: No, they figured out I think they knew how many

920
00:46:07,280 --> 00:46:09,919
Speaker 1: votes have been cast in total, and so they knew

921
00:46:09,920 --> 00:46:12,520
Speaker 1: that there was an excess and affected it. And I

922
00:46:12,560 --> 00:46:15,279
Speaker 1: don't think it flipped the answer either way. So it's

923
00:46:15,280 --> 00:46:18,839
Speaker 1: just sort of weird and mixed people suspicious, and you know,

924
00:46:18,920 --> 00:46:21,720
Speaker 1: it highlights something else, which is that our whole digital

925
00:46:21,719 --> 00:46:25,879
Speaker 1: infrastructure is sensitive to what's going on in space. We

926
00:46:25,960 --> 00:46:29,719
Speaker 1: recently had a really nice cosmic light show because there

927
00:46:29,760 --> 00:46:32,400
Speaker 1: was an extra amount of solar radiation which led to

928
00:46:32,840 --> 00:46:35,480
Speaker 1: northern lights all over the place on Earth. But that's

929
00:46:35,520 --> 00:46:38,520
Speaker 1: extra solar radiation and that can come at any time.

930
00:46:38,920 --> 00:46:43,080
Speaker 1: In the eighteen fifties, there was a really spectacular coronal

931
00:46:43,160 --> 00:46:47,040
Speaker 1: mass ejection, an eruption of charged particles from the Sun

932
00:46:47,080 --> 00:46:50,080
Speaker 1: which basically like a huge loop of plasma which heads

933
00:46:50,120 --> 00:46:52,680
Speaker 1: towards the Earth, which is just high energy cosmic rayse

934
00:46:52,719 --> 00:46:55,719
Speaker 1: that's what plasma is, right, and it can be like

935
00:46:55,880 --> 00:46:59,359
Speaker 1: billions of tons of materials. Most of these things missed

936
00:46:59,360 --> 00:47:01,359
Speaker 1: the Earth because they're it's pretty small and far from

937
00:47:01,400 --> 00:47:03,640
Speaker 1: the sun, but when it washes over the Earth, it

938
00:47:03,680 --> 00:47:07,280
Speaker 1: can devastate our digital infrastructure more than just like corrupting

939
00:47:07,320 --> 00:47:10,480
Speaker 1: a single bit on an airplane or in a voting machine.

940
00:47:11,000 --> 00:47:15,160
Speaker 1: This in the eighteen fifties, like set telegraph networks on fire,

941
00:47:15,160 --> 00:47:18,600
Speaker 1: like you know, sparks were flying. Yeah, it's crazy. And

942
00:47:18,680 --> 00:47:21,160
Speaker 1: if that happened today, like our digital infrastructure is not

943
00:47:21,280 --> 00:47:24,359
Speaker 1: protected from that kind of incursion, you wouldn't be able

944
00:47:24,360 --> 00:47:27,400
Speaker 1: to like shop for stuff online for days and days

945
00:47:27,560 --> 00:47:28,719
Speaker 1: while people fixed it.

946
00:47:29,040 --> 00:47:31,520
Speaker 2: I mean, can you imagine, like if something took out

947
00:47:31,920 --> 00:47:37,880
Speaker 2: all of our satellites, how absolutely pned we would be Yeah,

948
00:47:37,920 --> 00:47:41,160
Speaker 2: like nope, credit cards, I wouldn't have starlink Internet, there'd

949
00:47:41,160 --> 00:47:43,480
Speaker 2: be no dKu anymore everyone.

950
00:47:43,800 --> 00:47:46,760
Speaker 1: Can you imagine dot civilization crumbles?

951
00:47:46,880 --> 00:47:47,080
Speaker 3: Yes?

952
00:47:47,200 --> 00:47:48,640
Speaker 2: Right, yep, I agree.

953
00:47:48,880 --> 00:47:51,080
Speaker 1: And so in particle physics, we've thought about this a

954
00:47:51,080 --> 00:47:54,680
Speaker 1: lot because we're operating computers in a very high radiation

955
00:47:54,760 --> 00:47:58,239
Speaker 1: environment constantly, like we're creating that radiation. When you smash

956
00:47:58,280 --> 00:48:01,319
Speaker 1: two particles together, you generate huge numbers of protons and

957
00:48:01,360 --> 00:48:04,080
Speaker 1: neutrons and muons and all kinds of stuff, And then

958
00:48:04,160 --> 00:48:07,000
Speaker 1: we have silicon near the collision in order to measure

959
00:48:07,040 --> 00:48:10,239
Speaker 1: these things to detect these particles in exactly that way.

960
00:48:10,280 --> 00:48:12,399
Speaker 1: But if you run it for a while, eventually your

961
00:48:12,400 --> 00:48:15,520
Speaker 1: silicon gets trashed, you know, so every few years we

962
00:48:15,520 --> 00:48:17,439
Speaker 1: have to pull the thing out and send in new

963
00:48:17,520 --> 00:48:21,280
Speaker 1: silicon basically, And so people are doing stuff like exploring

964
00:48:21,320 --> 00:48:24,040
Speaker 1: whether we can use diamond instead. You know, we talk

965
00:48:24,080 --> 00:48:26,239
Speaker 1: about silicon as a semiconductor, but it's not the only

966
00:48:26,280 --> 00:48:29,000
Speaker 1: semi conductor out there. You can build these chips out

967
00:48:29,040 --> 00:48:32,960
Speaker 1: of diamond, which makes them more radiation hard which is

968
00:48:33,160 --> 00:48:38,680
Speaker 1: very expensive because there isn't a huge consumer diamond lithography

969
00:48:38,719 --> 00:48:41,560
Speaker 1: industry the way there is for silicon. So particle physics

970
00:48:41,560 --> 00:48:45,000
Speaker 1: tends to make its advances by like piggybacking on huge

971
00:48:45,040 --> 00:48:48,600
Speaker 1: trillion dollar consumer trends, and that hasn't happened for particle

972
00:48:48,600 --> 00:48:51,480
Speaker 1: physics that we don't have, you know, diamond chips yet,

973
00:48:51,800 --> 00:48:53,520
Speaker 1: but it's something that people are looking at that we

974
00:48:53,600 --> 00:48:55,680
Speaker 1: might have to do in the future in order to

975
00:48:55,719 --> 00:48:59,600
Speaker 1: protect our computers from cosmic grades or radiation more generally.

976
00:48:59,400 --> 00:49:00,920
Speaker 2: Can we take a us step back to like so

977
00:49:00,960 --> 00:49:04,320
Speaker 2: if we'd had another Carrington event type of thing, happen.

978
00:49:05,160 --> 00:49:08,359
Speaker 2: Is there something we could have done to protect all

979
00:49:08,400 --> 00:49:11,320
Speaker 2: of our satellites from an event like that? Like, should

980
00:49:11,360 --> 00:49:13,840
Speaker 2: we be encasing all of our satellites in diamonds? Is

981
00:49:13,840 --> 00:49:14,919
Speaker 2: what I'm asking.

982
00:49:17,400 --> 00:49:22,040
Speaker 1: It would make them so glittery and beautiful, that's right. Well,

983
00:49:22,120 --> 00:49:24,240
Speaker 1: essentially what you need is mass, Like either you should

984
00:49:24,239 --> 00:49:27,239
Speaker 1: build the chips themselves out of diamond to make them

985
00:49:27,280 --> 00:49:30,239
Speaker 1: radiation hard or is you just shield them, in which

986
00:49:30,280 --> 00:49:32,800
Speaker 1: case you need mass, and mass, as you know, is

987
00:49:32,840 --> 00:49:35,520
Speaker 1: expensive to put in space, and that's why it's so

988
00:49:35,600 --> 00:49:38,000
Speaker 1: difficult to have things like computing in space because it

989
00:49:38,000 --> 00:49:40,920
Speaker 1: needs the thing which is expensive to put. So I

990
00:49:40,960 --> 00:49:42,400
Speaker 1: think it would look awesome, but I don't think we

991
00:49:42,440 --> 00:49:44,360
Speaker 1: should bling up all of our satellites.

992
00:49:44,719 --> 00:49:48,480
Speaker 2: Okay, So for the foreseeable future, we're probably not going

993
00:49:48,560 --> 00:49:50,640
Speaker 2: to do anything about the fact that if we had

994
00:49:50,640 --> 00:49:54,040
Speaker 2: a Carrington event type of thing happen again, we would

995
00:49:54,040 --> 00:49:54,880
Speaker 2: be in a lot of trouble.

996
00:49:55,200 --> 00:49:58,640
Speaker 1: Yeah, that would be a massive investment in infrastructure, and

997
00:49:58,840 --> 00:50:00,880
Speaker 1: I don't see anybody doing it, though I think it

998
00:50:00,880 --> 00:50:03,319
Speaker 1: would be a good idea. But until then, we do

999
00:50:03,360 --> 00:50:05,719
Speaker 1: need to be aware that cosmic rays are everywhere. They

1000
00:50:05,719 --> 00:50:08,680
Speaker 1: are streaming through your room right now, and they are

1001
00:50:08,680 --> 00:50:11,719
Speaker 1: streaming through your computer. And sometimes they can flip a

1002
00:50:11,760 --> 00:50:13,839
Speaker 1: bit a zero to one. They can plow their way

1003
00:50:13,880 --> 00:50:16,160
Speaker 1: through a bunch of silicon and change the way those

1004
00:50:16,200 --> 00:50:19,360
Speaker 1: delicate electronics work. Most of the time this doesn't affect

1005
00:50:19,400 --> 00:50:22,279
Speaker 1: your computer, or it does it in an obvious way, or

1006
00:50:22,360 --> 00:50:26,360
Speaker 1: it's caught by error correction and fixed. But sometimes it isn't.

1007
00:50:26,600 --> 00:50:29,120
Speaker 1: And so next time your computer goes hey wire, you

1008
00:50:29,120 --> 00:50:31,239
Speaker 1: could blame it on your kids, or you could blame

1009
00:50:31,239 --> 00:50:32,560
Speaker 1: it on particles from space.

1010
00:50:32,840 --> 00:50:35,760
Speaker 2: Or the next time you get that super awesome science result,

1011
00:50:36,120 --> 00:50:39,520
Speaker 2: you should question yourself even more. That anxiety should keep

1012
00:50:39,560 --> 00:50:41,920
Speaker 2: you up all night, because maybe it was a cosmic

1013
00:50:42,000 --> 00:50:43,080
Speaker 2: ray and you were wrong.

1014
00:50:45,080 --> 00:50:50,080
Speaker 1: Maybe when you counted parasites you're off by one. All right, Well,

1015
00:50:50,120 --> 00:50:53,319
Speaker 1: thanks for taking this cosmic journey with us into how

1016
00:50:53,400 --> 00:50:56,960
Speaker 1: silicon electronics work and how they are vulnerable to particles

1017
00:50:56,960 --> 00:51:01,240
Speaker 1: from space. As always, we are grateful for your shared curiosity.

1018
00:51:01,440 --> 00:51:11,320
Speaker 2: Thanks everyone, have a good one. Daniel and Kelly's Extraordinary

1019
00:51:11,400 --> 00:51:14,640
Speaker 2: Universe is produced by iHeartRadio. We would love to hear

1020
00:51:14,680 --> 00:51:15,120
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1021
00:51:15,239 --> 00:51:18,200
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1022
00:51:18,400 --> 00:51:21,040
Speaker 1: have about this Extraordinary Universe.

1023
00:51:21,120 --> 00:51:24,080
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1024
00:51:24,080 --> 00:51:27,080
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1025
00:51:27,120 --> 00:51:27,520
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1026
00:51:27,800 --> 00:51:31,319
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1027
00:51:31,360 --> 00:51:34,560
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1028
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1029
00:51:35,800 --> 00:51:39,600
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1030
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1031
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1032
00:51:43,800 --> 00:51:45,359
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