Listener Questions 59: Interstellar probes and fractional electrons

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Speaker 1: Hey, everyone, A quick note to let you know that our preschool science TV show on PBS Kids called Eleanor Wonders Why just launched its second season. It's a show about curiosity and exploration and learning to use science to find your own answers to questions or Hey and I created the show a few years ago, and the second season has just premiered. We're so excited to share this new batch of stories and adventures. Check it out on PBS Kids. Eleanor Wonders Why.

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Speaker 2: Hey, Daniel, what do you think will happen first? That we discover aen life or that Aian life discovers us?

00:00:44
Speaker 1: Ooh, I really hope that they find us first.

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Speaker 2: Why?

00:00:48
Speaker 1: Because in that scenario, they're more likely to be smart and curious critters. If we find them first, it might just be that they're like microbial slime somewhere.

00:00:56
Speaker 2: Mmmm. How do you know they would be smart and curious? What if they're dumb hungry? Wouldn't we want to find them first and figure that out.

00:01:04
Speaker 1: If they're dumb and hungry, at least they're smart enough to have found us, right.

00:01:08
Speaker 2: What if they stumble upon it.

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Speaker 1: In their hunger fueled stupidity?

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Speaker 2: Exactly in indy. Case that we want to avoid them, we'll just feed them some microbial slime. If they're so dumb, they'll be happy with that. But what if we find them and they're smart and microbial slime.

00:01:25
Speaker 1: I'll put up with some slime if they're happy to share their knowledge.

00:01:28
Speaker 2: Yeah, But what if all they have are sticky facts, stick it to me or slimy data.

00:01:48
Speaker 3: Hi?

00:01:49
Speaker 2: I am Orge, my cartoonist and the author of Oliver's Great Big Universe.

00:01:52
Speaker 1: Hi. I'm Daniel. I'm a particle physicist, and I'm married to a biologist who tells me quote, microbes run the world. Makes me wonder when aliens come, who they would talk to first, us or the microbes that vastly outnumber us and out mass us.

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Speaker 2: Wait, your spouse thinks that microbes run the world? I mean, is she talking about politicians?

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Speaker 1: I think she's talking about like the metabolic processes of our ecosystem, you know, moving stuff around, processing stuff, transforming stuff.

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Speaker 2: So are they working for us or are we working for the microbes?

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Speaker 1: I think that remains to be determined. Maybe the aliens will help us figure it out.

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Speaker 2: But what if the aliens are clean freaks? And they don't like microbes.

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Speaker 1: It's hard to imagine even aliens surviving without microbes, you know Howso well, of course, we don't know what life might look like on those planets, but at least here on Earth, everything evolved from microbes, and microbes remain an essential part of all of our life processes. We couldn't survive without them.

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Speaker 3: Mmmm.

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Speaker 2: Slimy as it it is, we need microes. But anyways, welcome to our podcast, Daniel and Jorge Explain the Universe, a production of iHeartRadio in.

00:02:57
Speaker 1: Which we try to cut through all that mental slum and give you a clear picture for how the universe works, at least as much of it as we understand. We think that everybody out there who's curious and wonders about this incredible, amazing, but kind of bonkers cosmos deserves to have it explained to them. So on this podcast we did through all of your questions and your curiosity and try to bring you to the latest understanding of our universe.

00:03:21
Speaker 2: That's right. We try to give you a gut feeling about the universe and how it works, and fill you up with micro doses of knowledge and curiosity as we ponder what the universe is made out of, and how we're going to ever explore all of it?

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Speaker 1: Somehow amazingly, by taking these tiny little micro bites of knowledge out of the universe, we've built up something of an understanding of how the universe works. But of course vast critical foundational questions remain about the way the universe works. What are space and time? How can we have a quantum understanding of it? How did the universe all begin? And of course are we alone in it?

00:03:59
Speaker 2: Yeah, and seeings that there are too many questions for us to ever answer them all. But asking questions is how science starts and how we start building our knowledge of the universe.

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Speaker 1: And that science is powered by individuals asking questions. There's no monolithic institution out there somewhere churning out science. Is just a bunch of curious people wondering about the universe and being so passionate about their particular question that they devote their lives to figuring it out, even if that means climbing trees in the rainforests of Costa Rica or spending their lives in labs underground with lasers. It takes dedication, it takes curiosity. It takes perseverance to make progress on these questions. But it's not just professional scientists who power this human curiosity. It's everybody. Everybody who lives in this universe and demands answers about how it works.

00:04:46
Speaker 2: And that's because everybody has questions about deniverse. We all look around us and we all wonder how it all works, and we all learn about what scientists now, and still we.

00:04:55
Speaker 1: Have questions, and we want to hear your questions. When you read something in science journalism about a new discovery that was made that doesn't quite make sense to you, or when you watch a video that explains thermodynamics to you but it doesn't quite click in your brain, or when you hear us talk about something and you have follow up questions, please write to us to questions at Danielanjorge dot com. We really will answer every question.

00:05:18
Speaker 2: And sometimes we answer those questions here on the podcast.

00:05:21
Speaker 1: That's right. Sometimes the questions are really fun or I think everybody might want to hear the answer, and so we ask folks to record themselves asking it so we can joke about it and sometimes even answer it here on the pod.

00:05:32
Speaker 2: Sometimes answer it. Most often not.

00:05:35
Speaker 1: I don't know how often those answers are actually satisfactory, because usually the answer is we don't know. It might be this, or it might be that.

00:05:42
Speaker 2: I think we do a pretty good job of providing an answer, even if the answer is sometimes just a question.

00:05:50
Speaker 1: It's entertaining as much as it's educational.

00:05:52
Speaker 2: So today on the podcast, we'll be tagling listener question and number fifty nine. I love how we're still numbering these after all these years. Is there anyone keeping track?

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Speaker 3: Like?

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Speaker 2: What if we skip a number, would anyone notice?

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Speaker 1: I don't know. Maybe I did. How do you know exactly? That's what I mean. I'm gonna start giving these random numbers. Then next time it's going to be listening to questions six, four hundred and fifty two thousand.

00:06:23
Speaker 2: We should be like Taylor Swift and put in little codes or secret messages in these numbers.

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Speaker 1: Maybe I have been. How do you know? Yes, everybody dig into it.

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Speaker 2: You're the tte of Science Communication podcast.

00:06:36
Speaker 1: No, this is the Da Vinci code. Actually, I'm leaving secrets for future civilizations. Oh, I see, I see. You're not Taylor Swift, You're Da Vinci. No, I'm the Pope.

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Speaker 2: Yeah, let's keep going.

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Speaker 1: I don't know where you go from the pope, so hmm.

00:06:54
Speaker 2: But yeah, we do like to answer questions here on the podcast, and so today we have three pretty awesome questions, most of them about space exploration and space probes, but also an interesting question about splitting the electron and so let's jump right in. Our first question comes from Charles.

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Speaker 4: Hey, Daniel and Jorge. That was a recent listener question about traveling to a different star, and it got me thinking, given the state of technology today or in the near future, could we build a probe that could survive long enough to reach another star. A second part of it is when it does reach another star, could it send back meaningful data that we could receive. We do live in a real world, so I think that the answer should be limited to Apollo levels of funding, So about two point five percent of GDP for ten years.

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Speaker 1: Thanks a lot.

00:07:46
Speaker 2: All right, great question. It seems that Charles er wants to know could we send a probe to another star and would it even survive that long?

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Speaker 1: Yeah, I totally get where this question is coming from. We feel sort of like isolated in our little solar system and we can send probes to explore nearby planets, but we're always wondering, like what do those planets look like around other stars? And that we have incredible telescopes, the Hubble and James Web, we still can't visualize those planets and those solar systems. So the question basically is like, why don't we just send some science instruments to those solar systems, snap some photos, and send them back. Couldn't that be like revelatory. Couldn't we see incredible things things we might not even be able to imagine.

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Speaker 2: Right, Because I guess so far we've only been able to see up close six or seven planets, right, or eight planets? Where are we at in our solar system? Eight planets including eight planets, Yeah, including ours? I guess those are the only ones we've been able to see up close with probes, And so I guess Charles's question is could we send probes to another solar system to take pictures of other planets, maybe to find one that is habitable or one that has maybe things we haven't seen before on a planet.

00:08:58
Speaker 1: And Charles is also trying to be reasonable. It's not like let's pour all of the resources of humanity into this. Let's limit it to like, you know, two and a half percent of our GDP, which would be an incredible amount of science funding. I would love if we would spend two and a half percent of our GDP on science. Wow.

00:09:15
Speaker 2: Yeah, that would be amazing. So I guess his question is a two parter. First one is could we send a probe to another star? How long would that take?

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Speaker 1: Yeah? The challenge here, and the reason that is so difficult and we haven't done it yet, is these other stars are sort of like mind blowingly far away. Like even our solar system is pretty big, you know, like Pluto is very very far away. It's like ten thousand times further away than the Moon. So that's why even sending probes to the outer Solar system is an incredible feat. But the nearest star is much much further away than Pluto. It's like ten thousand times further away than Pluto. So it's not like the next solar system is like the next town over. It's like we're in a little town and there's another on the other side of the world. So these solar systems are very very far away. It's not just like a simple extension of our current technologies that's going to allow us to send probes there.

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Speaker 2: But I guess what is the nearest star to us.

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Speaker 1: The nearest star is Proximus Centauri. It's just under four light years away.

00:10:18
Speaker 2: Okay, four light years away. How many kilometers is that?

00:10:21
Speaker 1: That's thirty seven qua tillion kilometers away, three point seven times ten to the thirteen kilometers.

00:10:28
Speaker 2: Okay, that's a lot of zeros. But in space, I feel like you can go super duper fast.

00:10:33
Speaker 1: Right, Well, in space, you can go super duper fast if you can get up to high speed. Right. The speed of light, of course, is pretty fast. If you could travel at the speed of light, it would only take four years to get there. But the question is, can you get some piece of mass, some scientific probe up near the speed of light? If you want this thing to get there and to send us a message back in like less than one hundred years or so, then you need to get this thing up to like ten or twenty percent of the speed of light. It takes a few decades to get there, and that turns out to be quite a challenge.

00:11:04
Speaker 2: Wait, how fast do we need it to.

00:11:05
Speaker 1: Go something like ten or twenty percent of the speed of light for it to get there within a few.

00:11:09
Speaker 2: Decades, which is how fast.

00:11:11
Speaker 1: And the speed of light is three times ten to eight meters per second, so ten percent of that is three times ten to the seven meters per second, but.

00:11:18
Speaker 2: In like kilometers per hour.

00:11:20
Speaker 1: So the speed of light is like a billion kilometers per hour. So we need this thing to go like one hundred million kilometers per hour. Whoa.

00:11:28
Speaker 2: And that's if we wanted to go there and come back within a few decades.

00:11:32
Speaker 1: Now, that's just if we wanted to reach there in a few decades. And then we're hoping it's going to send us signals. We're not actually going to take samples from that solar system and fly them back. I think the first thing that it would be sent probes and then have them shoot the pictures back using messages rather than like actually returning.

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Speaker 2: Oh I see, So you want it to go there in a few decades and then it sends a signal back which comes back in four years.

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Speaker 1: Yeah, exactly. And so the challenges are getting the thing up to that speed, having it survive the journey, and sending us a message back. Whoa.

00:12:02
Speaker 2: And so I guess it's hard to get up to that speed and space.

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Speaker 1: It is hard to get up to that speed in space depending on the technology you use, Like if you use the kind of technology we use in like the Space Shuttle and in most of our rockets, then you run into a really difficult problem, which is you not only need to accelerate your payload like your science probe, you need to accelerate in the fuel that you're using to accelerate it. So you need a lot of fuel to get up to high speed. You're not burning all that fuel initially, it's not like one big boost and then boom, you're going ten percent of the speed of light, which means that a lot of the fuel needs to accelerate the rest of the fuel, which means you need more fuel for that, which means you need more fuel for that, And then pretty quickly your ship is almost all fuel.

00:12:43
Speaker 2: Right, Like to put a rocket or to put even a small satellite into orbit, you need a giant rocket, and those rockets are like mostly filled with fuel.

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Speaker 1: Yeah, exactly, they're mostly filled with fuel. So the practical limit of rocket technology, like rockets we could actually build and send towards other solar system it would take tens of thousands of years for those probes to reach those solar systems because we couldn't get them anywhere near ten percent of the speed of light using like solid or liquid fuel rocket technology.

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Speaker 2: Wait, how do you know what's the fastest we could accelerate today.

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Speaker 1: Well, it's not like exactly a fastest speed, but if you think about like simple extensions of the current rockets, you know, doubling tripling them, this kind of stuff, you don't get anywhere close to ten percent of the speed of light, and so it would take tens of thousands of years.

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Speaker 2: Like maybe, for example, the voyagerer pros that have now left the Solar System, how fast are they going?

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Speaker 1: Yeah, so Voyager is the furthest man made object currently. Was launched in nineteen seventy seven and it's only gone one hundred and sixty three au, like that's the distance between the Earth and the Sun. So it's just out of the edge of the Solar System, and it's been going for almost fifty years. It's traveling at like three point six au per year. But that's not really a powered object in the same way, like we launched it and we sent it off in a space and it's got a little bit of like nozzle and thruster for control, but it's mostly just cruising. It's never really designed to go at very high speed.

00:14:07
Speaker 2: Well, you mentioned sort of an interesting idea, like what if we gave it a whole bunch of acceleration at the beginning, like if we exploded it out of a gun or something.

00:14:15
Speaker 1: Yeah, so there are other ideas for how to get something to another solar system other than just like do a dumb rocket. There was a really fun idea in the fifties and sixties called project Orion, which said, like, let's blow up nuclear weapons behind the spaceship, so who can like surf a wave of nuclear weapon explosions. This is called project Orion.

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Speaker 2: This is yeah, I mean, what could go wrong?

00:14:38
Speaker 1: This is Freeman Dyson's idea. And people kind of took this semi seriously for a while until there was a treaty saying no blowing up nuclear weapons in space, which basically killed this whole plan.

00:14:49
Speaker 2: But wait, so it's a political problem.

00:14:52
Speaker 1: That's a political problem. Yes, And he wrote a paper decades and decades ago estimating that this ship would take between two hundred and one thousand years to get to Alpha Centauri if it was powered by nuclear complosions.

00:15:04
Speaker 2: WHOA, that's a long time. Do you think that's what Charles meant? Do you think that's too long?

00:15:11
Speaker 1: I think that's too long. I think you want to send this thing and then have it send you back data, like in the lifetime of a scientist. You know, you can imagine somebody building this thing as a young scientist, sending it out there, getting the data back before they retire seems like a reasonable strategy. I'm all for multi generational science projects, but it just seems like too long to wait.

00:15:30
Speaker 2: Well for you, because you're not the results exactly.

00:15:34
Speaker 1: I want the answers.

00:15:35
Speaker 2: Think about your grade grade grand kid scientist and how excited they would be to receive a message from this probe.

00:15:42
Speaker 1: Yeah, as they're scratching out of living in a cave somewhere when civilization has fallen and that data is beamed back from that other solar system and then just splashes on the ground totally ignored.

00:15:52
Speaker 2: M I guess that's the other part of it, is what can happen in a few hundred years exactly, Like the United States, it is not even more than three hundred years exactly.

00:16:02
Speaker 1: So that's why people have been thinking about faster ways to get stuff to other solar systems. There are other ways to power these rockets, like ramjets, which are a technique that scoop up fuel as you go, because you know, space is not empty, it's filled with protons, and protons are hydrogen and you can use that as propellant. So there are techniques for like scooping up hydrogen and using that along the way. But I think the most realistic is actually maybe the most science fiction y, which is a solar sail pushed along by lasers. And the idea is to escape this rocket trap by not bringing your fuel along at all. Just have a huge sail and point a laser beam at it, and that'll push the probe along and the probe doesn't have to carry the fuel with it.

00:16:43
Speaker 2: Well, you'd have to be really accurate, though, right, to like shoot this tiny little probe in the middle space really far away.

00:16:50
Speaker 1: Yes, you would have to be accurate because these things are tiny targets from like an angular point of view. But in principle you could also maybe steer these things a little bit. You have a magnetic fin that you could use, you know, to take advantage of interstellar magnetic fields, et cetera.

00:17:06
Speaker 2: So if you do that, how fast can you get a probe going?

00:17:09
Speaker 1: So they suspect that if you build these things with huge sales, we're talking kilometer sized sales, and you build a huge beam of lasers, like a square kilometer array of lasers that can pump out like giga WoT hours of energy, then you could get these things realistically up to ten or twenty percent of the speed of light, which means they could reach the neighboring star system in like twenty ish years.

00:17:32
Speaker 2: WHOA, And with this fit within the budget that Charles laid out.

00:17:35
Speaker 1: It depends on energy costs. Mostly a few gigawatt hours of energy is a pretty big fraction of our energy output. If we can make energy production more efficient or somehow harness energy from the Sun to power these lasers directly, or something that would be more productive.

00:17:51
Speaker 2: Could you just build like a giant magnifying glass to fill this of the light from the sun put it out there in space.

00:17:57
Speaker 1: Yeah, potentially. It's a funny thing to try to play in these projects because you never know if you should start building today or wait five years until the technology has improved so that you could actually get your probe going. Faster, Like which probe would actually arrive first, the one you start building today or the one you start building in ten years that might get up to a higher speed.

00:18:18
Speaker 2: Yeah, Those giant magnifying glasses just keep getting better and better every year.

00:18:23
Speaker 1: And then, of course this challenge is in flight. Right while you're flying from here to there, you have to worry about like micrometeorites tearing your sale or destroying your space probe or all sorts of stuff.

00:18:33
Speaker 2: Yeah, it's kind of what Charles asked as the second part of his question is would the probe even survived that long?

00:18:38
Speaker 1: It's hard to say. And one of the current plans I read from the Breakthrough Starshuk program is to send a bunch of probes, like not an individual one, but like a whole array of small probes. The idea of being you're spreading your risk. But it is tricky because even a tiny particle like a hundredth of a millimeter in size at very high speed we're talking, you know, twenty percent of the speed of LFE could basically destroy that kind of probe.

00:19:02
Speaker 2: Hmmm, even if you put it like a shield in front.

00:19:05
Speaker 1: Yeah, there is possibility to have shields. We talked about on the podcast once to have these whipple shields, like thin layers of graphite that might make it work. I did read an analysis of how likely these probes are to survive, and the famous Avi Lobe says, quote, we did a thorough analysis, taking all relevant physics into consideration. We didn't see any showstoppers. But you know, thorough analysis by Avi Lob. Who knows what that means.

00:19:30
Speaker 2: I'm not sure who Avi Lob is, but he sounds very sure of himself.

00:19:33
Speaker 1: Well, remember we talked about him on the podcast before. He's the guy who claimed to have found interstellar material from sperials under the ocean, and then planetary scientists came along and they were like, yeah, you don't really know what you're talking.

00:19:44
Speaker 2: About, So where are we quoting him on the podcast?

00:19:48
Speaker 1: Incredible, so we can dunk on him, of course.

00:19:51
Speaker 2: But I guess maybe even a bigger question is even we could get a probe that far, would it even be able to talk to us? Because you know, sending a signal that bar takes a lot of energy.

00:20:01
Speaker 1: Yeah, it's tricky, and you're fighting the one over are squared, Like if you just broadcast from Earth, you might think our signals are pretty strong, but the signals get weaker and weaker, and if you're ten times further then the signals one hundred times weaker, and if you're a thousand times further, the signal gets a million times weaker. And so broadcasts of that strength can't actually be picked up by technology that we have further than like a couple of light years. And so in order to get a signal from another solar system two hours, you don't want to broadcast in every direction. You want as tight a beam as possible. And so if you have, for example, a laser on board, it in principle could send you a signal which would outshine that star in particular wavelengths that you could pick up.

00:20:42
Speaker 2: Interesting. All right, So it sounds like the answer for Charles is that, yeah, it is possible for us to send a probe that goes to another planet, to the nearest star and census back signals within the budget. We just kind of have to do it, right.

00:20:57
Speaker 1: Yeah, it's an exciting moment because we're like and on the edge of having all these technologies come together where we really could actually do this. It would still be very very expensive, but mostly I think at this point, it's a political and organizational challenge. We're in the place. We are in lots of scientific fields where we could buy knowledge about the universe. We have enough money. It's just a question of do we have the will, do we want it enough right?

00:21:19
Speaker 2: Do we want to buy it or do we want to just leave it in our shopping cart for.

00:21:24
Speaker 1: A while, wait till the price goes down.

00:21:27
Speaker 2: Yeah, wait for that sale. That's Cosmo Amazon sale in the sale on solar sales. But yeah, scientists, get on it, because, let's face it, Daniel is not getting any younger, and he really wants to do these pics is before he dies.

00:21:42
Speaker 1: You know, I'm not the only one who's not getting any younger. That's true of literally everybody.

00:21:47
Speaker 2: You seem especially to want to see these pictures.

00:21:49
Speaker 1: I do want to see these pictures. Absolutely, Yes, Congress, please send us one hundred million dollars we can spend on this.

00:21:55
Speaker 2: Or let's freeze Daniel and when we finally get the pictures back, well.

00:22:01
Speaker 1: Wake them up the frosty. That sounds pretty good. I do have fantasies about freezing myself and waking up every hundred years just to get like updated on physics. That would be pretty cool.

00:22:12
Speaker 2: Oh interesting, but just you, not your family.

00:22:17
Speaker 1: Everybody else has to stay awake so they can do the physics and then I can get updated. Right, that's right.

00:22:22
Speaker 2: Yes, I think it sounds like you need to start like a cult. Maybe you used to start by having a podcast.

00:22:27
Speaker 1: Perhaps maybe that was the plan the whole time.

00:22:32
Speaker 2: Maybe you read the numbers in our listener question titles. You'll get instructions for how to how to join, how to join the cult, and mix the kool aid?

00:22:42
Speaker 1: Don't cult leaders usually like solicit donations from their members though, we should have gotten on that.

00:22:46
Speaker 2: Oh yeah, maybe that's in the instructions or maybe you should have put that in the instruction.

00:22:50
Speaker 1: Yeah, that's right, it's banking information.

00:22:53
Speaker 2: All right. Well, thank you Charles for that question. Let's get to our next question. This one is kind of also about space prodes, but from a different perspective, so let's dig into that. But first let's take a quick break. All right, we're answering listener questions here today, and our next question comes from Ted.

00:23:23
Speaker 1: Hi, Daniel and Joge.

00:23:24
Speaker 2: Here's my question.

00:23:25
Speaker 3: I've always been fascinated by the voyager space probes and their journey through our Solar System out into interstellar space. I believe it will be around forty thousand years until Voyager one will reach the proximity of another star. I've always wondered if another civilization has sent a voyager like probe in our direction and it passed through our Solar system, would be a even be able to detect the presence of an object that size be If we were able to detect it, would we be able to intercept it and bring it back to Earth so that we could retrieve its gold record or the equivalent audio medium that the alien civilization who sent it had included?

00:24:15
Speaker 1: Thanks?

00:24:16
Speaker 2: All right, pretty cool question. Basically, I feel like that question is couldn't Alien have probed us?

00:24:22
Speaker 1: Yeah, this is a fun question. Couldn't Alien have probed us?

00:24:25
Speaker 2: Or?

00:24:25
Speaker 1: If alien probes arrive, could we even see them? To me, this is a really dark scenario that like an alien voyager probe could pass to the Solar System and we could not spot it. Oh my god, what a tragedy.

00:24:37
Speaker 2: Well, maybe if we assume that you're assuming we want to meet these aliens.

00:24:43
Speaker 1: I don't need to assume that I want to meet these aliens. I already know that somebody sends us a probe. I want that thing. Oh my gosh, wouldn't you want to see it?

00:24:50
Speaker 2: But I guess the question is how likely is it that maybe we haven't seen a probe that has come near us? Or maybe that's the main point, is it? It depends on how close to us it flew.

00:24:59
Speaker 1: Well, we're definitely sure we have not yet seen any alien probes. I mean, unless the government has some secret program and is captured in an alien probe and is studying it at Area fifty nine or Area sixty two or whatever. But let's assume that we have not yet captured any alien probes. I think it's a fun question to explore, like could we see an alien probes? Like if one hundred aliens shot their probes in our solar system, what fraction of those could we see right?

00:25:23
Speaker 2: And seeing them meaning like we see them with their naked eye right or with some sort of radar.

00:25:29
Speaker 1: Yeah, we have a lot of technology to spot these things. I mean, number one, if they somehow still have power after their ten thousand year journey to our solar system and they're broadcasting, then yeah, we're going to spot them. You know, because any signal like that we will capture.

00:25:43
Speaker 2: Wait, why would they need to have been space that long? Couldn't they do the same thing we just did in the first question, And maybe the probe is only twenty years old.

00:25:51
Speaker 1: Yeah, it's possible. And space craft can have like nuclear powered batteries, they can last four decades, and so it's certainly possible that you know, they send a solar sale or they have some even better technology and it gets here and it still has power. But broadcasting takes a lot of energy, and so it seemed unlikely to me. But that's possible, and that would be easy, right if an alien probe comes and is sending signals in some band that we're monitoring, yeah, we're going to spot that. I think the harder thing is some like dead relic of an ancient civilization that's floating through our solar system. Could we spot that?

00:26:23
Speaker 2: Well, it's sort of I feel like it's the same problem, Like it could also be a probe, but maybe it's sending laser signals back to its own planet that we can't see, right, so it.

00:26:32
Speaker 1: Could be silently spying on us.

00:26:34
Speaker 2: Yeah, yeah, so I guess the question is if something that was not naturally occurring, like a meteorite was flying around us, around the Earth, Could we first of all spot it and could we tell that it is not an asteroid?

00:26:49
Speaker 1: What media clue would be its trajectory? Like, we monitor a lot of things in the Solar System and we measure their orbits, mostly because we're curious about whether they're going to slam into the Earth. Has been monitoring asteroids and comets and all sorts of stuff, and most of those orbits are consistent with having gone around the Sun a bunch of times. But sometimes, very rarely, very occasionally, we see something that clearly is coming into the Solar System that was not gravitationally bound by the Sun. The most famous example is O Muamoa, which is a rock that came from another Solar system just like drifted through ours. We spotted that because of its weird trajectory. That's what made it different from all the other rocks in the Solar system.

00:27:30
Speaker 2: Right, Like, maybe Omo was an alien probe from an alien civilization.

00:27:35
Speaker 1: Right, Yeah, now you're sounding like a vilobe, right, That was his other claim.

00:27:38
Speaker 2: I'm just saying, maybe I'm necessarily after thorough analysis, I can tell, let's say, alien probe.

00:27:45
Speaker 1: Yeah, exactly, And that's what makes these things so exciting, Right, they're coming from another solar system. Are they just a chunk of ice or rock, or are they actually a relic from another civilization, et cetera, et cetera. And so we want to study these things. But the exciting thing is that we can usually tell if something is interstellar or if it's part of our solar system. So these things stand out because of their motion and because we're trying to track things moving in our solar system. We're pretty good at spotting those things.

00:28:11
Speaker 2: M I thought you were going to say that we could tell it's an alien pro because maybe it's not going in a straight line or maybe not going in a natural sort of gravitational orbit line.

00:28:22
Speaker 1: Absolutely, that's an important factor as well. Like number one is where do we think it came from? Number two is is it moving gravitationally? Like If it's moving as if the only forces on it are due to gravity, gravity the Sun and Jupiter, etc. Then that makes it more likely to just be like a rock or a chunk of ice. But if it's thrusting, if it's accelerating, if it's deviating from a gravitational path, then it's almost certainly not natural. Although in the case again of Omuamua, that thing was not just moving gravitationally. There was a little bit of thrust, though now we're pretty sure that was due to ice boiling off the back of it as it left the Solar System, which provided a little push hmmm.

00:29:01
Speaker 2: Or I guess you know, just sort of how we do it with our space probes. We basically only do small corrections every once in a while, right, Like we when we plan out the navigation of our space pros, we try to make it as natural as possible, right, because that saves you the most amount of energy.

00:29:17
Speaker 1: Exactly. We're very sparing with our use of that fuel because you can't put a lot on board. It makes the thing heavy and you have a long way to go. It's a voyager, for example, still has a little bit of fuel left, even decades and decades after it took off, because mostly its trajectory was determined by gravitational slingshots around Solar System objects.

00:29:36
Speaker 2: So it's possible we may not be able to detect this probe by studying its path.

00:29:41
Speaker 1: That's right, though, if it comes from outside the Solar System. I think we would identify it as a non Solar system object, but that depends on whether we can see it. Like we can see stuff in the Solar System, but we can't see everything. You know, the Sun is bright, but it doesn't light up all of space in the way that you can see every rock. Rocks have to be like shiny enough and big enough and oriented the right way for the light to bounce off of them and come to Earth. There's a lot of dark rocks in the Solar System we've never seen.

00:30:09
Speaker 2: Before, right, and a lot of tiny rocks that we just can see. They're too small for us to even notice.

00:30:15
Speaker 1: Yeah, exactly, And most of the stuff we've seen in the Solar System is bigger than like the Voyager probe. We can see smaller rocks, but they have to be kind of brighter. So we've seen all the big rocks in the Solar System. We're very confident about that. But as the rock size gets smaller and smaller, then the fraction of them we've seen starts to drop pretty quickly. So certainly is possible for an interstellar probe to enter the Solar System. And if it's dark enough and small enough for us to not notice.

00:30:40
Speaker 2: Yeah, I mean, omoom Wo was huge and we still can definitively tell right, we can't get a closer picture of it.

00:30:46
Speaker 1: Oh mum Woo was pretty big and we couldn't study definitively. One reason is that we didn't really identify it until it was already past its point of closest approach, so zipping away from us in the Solar System. If we spotted these things sooner, and we could identify them before for they had their closest approach to Earth, then there's a possibility we could like rapidly launch something to intercept it, or at least come near it and like snap a bunch of quick photos. But oh Mumu was so frustrating because it's basically too late to launch anything to go sample it or take pictures of it. It was already zipping on its way out of the Solar System.

00:31:19
Speaker 2: And oh, I feel like we just happened to have seen it. Is it possible we've missed other o'mu moos in the near past or will miss them in the near future.

00:31:29
Speaker 1: It's certainly possible. Omoomu is something we spotted pretty soon after we turned on a new set of telescopes, the pan Stars telescopes, which are excellent at this So now that we have those guys operating and we're building more of these things in the future, I think we're just increasing our chances of spotting these things. But there's always a chance that we miss them. Right, you have to be looking in the right place at the right time, and we have a tiny number of eyeballs scanning a very large solar system. We should definitely be spending more money on telescopes.

00:31:57
Speaker 2: Well, here's a question. What if the Aliens designed a stealth space prow Could they do that? Could they design it in a way that maybe doesn't reflect light or reflects it, you know, like maybe it has weird angular mirrors in its surface that would make it super duper hard to spot.

00:32:16
Speaker 1: Yeah, exactly, you basically just paint the thing black and it's invisible. If it absorbs the radiation instead of reflecting it, then it's gonna be very very hard for us to see it.

00:32:24
Speaker 2: M what if they paint it infinite black or infinite dark, then.

00:32:28
Speaker 1: They're going to owe you license because.

00:32:30
Speaker 2: That'shactly, Maybe I sold them to paint.

00:32:34
Speaker 1: Maybe you're an alien, And this whole question is just to try to figure out how to sneak by our defenses.

00:32:40
Speaker 2: Yes, that's my cult. Then I'm starting, but I want to hide the code for sending me money. Just got to hoorhead Han dot com and use the Venmo coat. All right, So it sounds like the answer for Ted is that, yeah, it's totally possible. Then an alien species has sent approach to us and taking pictures of us, study does and we could have maybe not noticed at all.

00:33:03
Speaker 1: It is possible. I think it's not likely unless they're trying to hide it because we have pretty good telescope scanning the solar system. So I think at least it helps me sleep better at night to think that we have a pretty good chance of spotting an alien voyager.

00:33:15
Speaker 2: But well, I guess also, I mean, usually we only have a pretty good view of half of this guy, right, Like, what if they're smart enough to come at us from the sun.

00:33:23
Speaker 1: Yeah, it would be much more difficult if it comes from behind the sun and then around the sun and then straight at us. You know, like a fighter pilot coming in from the sun.

00:33:31
Speaker 2: Yeah, exactly.

00:33:32
Speaker 1: If you're intentionally sneaky, it would not be hard to go unnoticed. But if you're friendly and you're trying to advertise your existence, then it's not that hard to build something which with a good probability of being seen.

00:33:43
Speaker 2: But technically, I think the answer is it is totally possible.

00:33:46
Speaker 1: It is totally possible.

00:33:48
Speaker 2: Yes, we've been probed, well, probe up.

00:33:50
Speaker 1: There was it up the intellectual wazoo.

00:33:52
Speaker 2: Yes, yes, that's right, it's a family friendly podcast. All right, well, thank you Ted for that question. Now let's get to our last question, and this one is about splitting the electron, so that's not split hairs about it. Let's get to it. But first let's take another quick break. Robert answering listener questions here today, and our last question comes from Inyaki.

00:34:26
Speaker 5: Hi Danielle lan Jorge. I was curious about the possibility that in certain specialized state of matter, electrons can splinter into a fraction of their whole, splitting the electron chart, what will be amazing? Thank you, very great podcasts.

00:34:43
Speaker 2: All right, interesting question. It seems to be about this idea that they have in certain field to physics where you have like fractional electrons.

00:34:53
Speaker 1: Right. Yeah. I think that this question is stimulated by a bunch of news articles that came out that were little sensationalist about something that was discovered in condensed matter physics that led people to believe that the fundamental electron that we know and love has somehow been split into sub electrons with fractions of an electric charge. WHOA.

00:35:14
Speaker 2: That was actually in the news.

00:35:16
Speaker 1: There was a bunch of popular science news articles describing these studies and giving people that impression. I know because I got like ten emails from listeners asking about it.

00:35:26
Speaker 2: What were some of the headlines.

00:35:27
Speaker 1: Here's one from MIT News that says, quote, electrons become fractions of themselves.

00:35:32
Speaker 2: WHOA, that is pretty sensational and from MIT.

00:35:38
Speaker 1: And it says in the article, in very special states of matter, electrons can splinter into fractions of their whole. WHOA.

00:35:44
Speaker 2: That does sound like you're splitting the electron. So what's really going on here?

00:35:49
Speaker 1: So first of all, number one, we have not split the electron. Okay, that's not what has happened here. Instead, they've created some new kind of funky material that displays some new weird property, and there's like a layer of condensed matter theory interpretation on top of that that says that it's sort of like if you had fractional electrons.

00:36:08
Speaker 2: I feel like that was a lot of legalise there in your explanation there. So what was the experiment was it that they did?

00:36:17
Speaker 1: This is the whole field of physics, soft mataphysics or condensed mataphysics that tries to build new, weird kinds of materials in order to force electrons and other particles to do weird quantum stuff. So in this case, they're using graphene to these regular lattices of carbon. They use it because it has strange electronic properties, like the electrons sometimes can only move basically in two dimensions in between the layers of graphene. So what they do is they make structures of graphene. So they have like five layers of graphene. And you remember, to make these layers of graphene is actually quite tricky, use like Scotch tape the stuff. Yeah, to put like thin layers of graphine off and actually have these super thin like two dimensional stuff. And what happens when you build these things is electrons behave in new weird ways. Now, this is not changing what the electron is. The electron is not being split, The electron is not new. We're not looking inside the electron. What's happening here is that we're putting a new interpretation on what we're seeing. This is what we call quasi particles. You know, particles are like ripples and fundamental quantum fields. Quasi particles are things that obey the same mathematics as particles, but are ripples in things that are not fundamental fields. Like for example, sound is a ripple in air, right, but air is not like a fundamental field in the universe. It's just a bunch of atoms. But still you can talk about sound in terms of like phonons, particles of sound moving through the air. So you can use that kind of mathematics to talk about ripples in stuff that are not fundamental quantum fields. So when you make electrons operate in this weird way inside graphene, then what you're doing is you're making them operate in a way that they create these quasi particles, some of which have fractional electric charge. But they're not like new fundamental particles we're discovering in the universe. It's just like a layer of mathematical interpretation on top of the complicated stuff that the electrons are doing underneath.

00:38:13
Speaker 2: Right. I think We've done a few episodes on this, and the idea is that, you know, sometimes it's sort of like things like bubbles in water, right, Like a bubble in water is not really a particle of something or water. It's just sort of like the absence or a little void of water and it sort of behaves. It looks like a thing because it's moving through the water and it's bubbling up, and you think, oh, there's a little circle that moves up, But it's not actually a particle or a thing. It's just sort of a void of water molecules that's moving together as if it was a thing.

00:38:46
Speaker 1: Yeah, exactly, And let's take that example and run with it. Say you try to then measure properties of that void and you're like, well, what is the mass of it? And you're like, oh, well, compared to the water, there's no mass there. So we could imagine having like negative mass. Could we use negative mass in our mathematics to describe the motion of these things? And that's essentially what's happening here, is that they're adding a layer of mathematics on top of this condensed matter experiment where lots of electrons are swooshing around and obeying weird mathematics quantum mechanics, and in that mathematics they use fractional electric charges. That doesn't mean they've seen any fundamental particles with fractional electric charges. It just means that, like when the electrons get together, they do a complicated dance, and you can interpret that at a sort of a higher level when you zoom out, as if there were least quasi particles with fractional electric charges.

00:39:36
Speaker 2: Yeah, the way I understand it, it's sort of like you have this layer of graphene, right, and you have these electrons kind of on the surface of that layer, and they're just moving around like in a two dimensional table, and sometimes you get these bubbles in that sea of electrons, and those bubbles then have like a fractional charge of the electrons. Is that sort of a good way to look at it.

00:39:57
Speaker 1: That's a good way to look at it. They're actually a p probate using the quantum Hall effect, which is a complicated effect that electrons can do when you have an electric current one direction in a magnetic field and another direction. And so they're observing not just the quantum Hall effect, but the fractional quantum Hall effect. That's what this experiment is actually about. But you're right, essentially, they're looking at the emergent behavior of a bunch of electrons doing weird things. And you know, all these popular science articles that are talking about it, none of them really explain what the quantum Hall effect is because it's really complicated and kind of a mess to understand if you're not deep into condensed matter theory. So I totally understand like why they didn't dig into the details of it, But I think it's a little misleading to write that they've split the electron into fractional charges because they really haven't done that.

00:40:43
Speaker 2: Well. I think maybe what they mean then is sort of like they created something that behaves like a particle that has the fractional charge of an electron.

00:40:51
Speaker 1: Yes, that's right.

00:40:52
Speaker 2: So then you maybe get into a little bit of philosophy of like is that actually a thing or not a thing? How do you even know that electrons are a thing?

00:41:01
Speaker 1: Yeah, electrons are a thing and they have a certain charge. We don't know that they're a fundamental thing, right, totally find a zoom out and say, look, here's the thing, even if it's made out of other stuff, Like we call the proton a thing. It has a charge, but it's actually made of other charge things inside of it. Right, It might also be true of the electron, And that would be very exciting. If you could take the electron apart into little bits and show that it's a charge of negative one comes from other little fractional charge bits, that would be very cool. That would fundamentally change our understanding of the nature of reality. That's not something we've done here today. That would be huge milestone.

00:41:37
Speaker 2: But I wonder if it's possible that, you know, maybe the electron fields are not quite what we expect, and when they mix together they somehow do create these sort of things that are fractional charge and maybe they're just as real as the electrons.

00:41:51
Speaker 1: Yeah, and this is totally a fascinating and valuable direction of research. But it's not asking what is the electron field made out of? Fundamentally, what is it's nature. It's asking what complicated stuff can the electron field do under certain conditions. This is not telling us anything about the nature of the electron. It's telling us about the complexity that arises when a bunch of electrons come together. And so that's fascinating totally worthwhile.

00:42:16
Speaker 2: Right.

00:42:16
Speaker 1: The whole field of candense matter physics is basically that what complicated stuff can a bunch of tiny particles do when they get together, And it turns out, Wow, they can do all sorts of amazing complicated stuff bananas, an ice cream and people and superconductors and all that stuff. It's glorious. But none of that tells us anything about the nature of the electron itself, which is I think what this article was suggesting.

00:42:36
Speaker 2: Could it maybe could it? You know, by finding out that, oh, these are electron fields makes in a weird way that we didn't think of before. Maybe they're not fundamental.

00:42:46
Speaker 1: Yeah. Absolutely. By exploring what the electron field is doing, you might see some discrepancies from your predictions that point towards clues that tell you that you're understanding the electron field is wrong. Yeah. Absolutely. That also is not what's happened here. Like the fraction quantum Hall effect was predicted, it's understood theoretically, it had never been seen before experimentally, So that's cool, But again, it doesn't tell us anything new about the electron field itself. That doesn't mean again, this is not a valuable area of research. And if they see something weird and unexpected, they could lead to a discovery that does help us unravel what the electron field is. But this is more about like what do electrons do when we combine them into weird ways than like what is the electron itself?

00:43:28
Speaker 2: All right? Well, then to ask for Nyiki is that they did not split the electron, or at least Daniel doesn't like an interpretation of the results, But it may I'll be telling us a little bit more about the nature of the electron and what it can do, and what it's made out of, and whether it could maybe be split in the future exactly.

00:43:47
Speaker 1: And questions of the fundamental nature of the universe are not the only valuable science questions. We can do science at the tiniest scale to try to reveal what are the basic units of the universe, but there's still a lot of really important open questions about what those basic units do when they come together and how they make the complexity of our world. Science is valuable at all sorts of different scales, from like psychology all the way down to particle physics. All of it is teaching us something about our wonderful universe.

00:44:13
Speaker 2: Now, does that include cult studies.

00:44:15
Speaker 1: Also, absolutely, yes, can two podcasters raise millions of dollars to fund their interstellar probe? That's a fascinating question of science.

00:44:25
Speaker 2: Yes, and the answer is hidden in the numbers of our listener question titles.

00:44:32
Speaker 1: And in Jorges Venmo code. Yes, that's right.

00:44:36
Speaker 2: I'll give you the answer if you pay. How about that?

00:44:39
Speaker 1: Oh man, you better come up with the answer then.

00:44:44
Speaker 2: All right. Well, thanks to all of our question askers for these great questions, and thanks to all of you for listening to our listener questions.

00:44:51
Speaker 1: Thanks to everybody who writes in with their questions. I love reading them, I love answering them. Please don't stop sending them, and don't stop being curious about the universe. Your personal curiosity about science and about the universe that's pushing forward the whole human project of science and exploration of our gospels.

00:45:09
Speaker 2: That's right, Daniel, I think you're saying, don't stop believing. Just listen to that feeling. All right, Well, weeled you enjoyed that. Thanks for joining us, See you.

00:45:18
Speaker 1: Next time for more science and curiosity. Come find us on social media, where we answer questions and post videos. We're on Twitter, disc org, Insta and now TikTok. Thanks for listening and remember that Daniel and Jorge Explain the Universe is a production of iHeartRadio. For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows.