Why is the speed of light so important in physics? Why does the value not matter at all? And why does it have the speed that it does? I discuss these questions and more in today’s Ask a Spaceman!
Support the show: http://www.patreon.com/pmsutter
All episodes: http://www.AskASpaceman.com
Follow on Twitter: http://www.twitter.com/PaulMattSutter
Like on Facebook: http://www.facebook.com/PaulMattSutter
Watch on YouTube: http://www.youtube.com/PaulMSutter
Read a book: http://www.pmsutter/book
Go on an adventure: http://www.AstroTours.co
Keep those questions about space, science, astronomy, astrophysics, physics, and cosmology coming to #AskASpaceman for COMPLETE KNOWLEDGE OF TIME AND SPACE!
Big thanks to my top Patreon supporters this month: Matthew K, Justin Z, Justin G, Kevin O, Duncan M, Corey D, Barbara K, Neuterdude, Chris C, Robert M, Nate H, Andrew F, Chris L, Jon, Cameron L, Nalia, Aaron S, Kirk T, Dr. Johnny Fever, Tim R, Joe R, Neil P, Bryan D, Irene P, Dustin R, Matt C, Iothian53, Steve P, Debra S, Ken L, Alberto M, Ron W, Chris L, Mark R, Alan B, Stephen J, David P, John F, Maureen R, Frank T, Craig B, Jesse A, Steven L, Ulfert B, Dave L, Stace J, S Stark, Richard K, Carol S, Stephen M, Grace M, Jeremy K, Russell W, David B, Tamara F, Robert B, Fr Bruce W, Catherine R, Nicolai B, Sean M, Nate H, Edward K, Ped, Chuck C, Jose Pablo V, Stephen S, Elizabeth W, Eric F, Tracy F, Roger G, Callan R, Nils M, John W, George, Tom G, Monika, Michael H, Tom, Sarah K, Robert S, and Gerald!
Music by Jason Grady and Nick Bain. Thanks to Cathy Rinella for editing.
Hosted by Paul M. Sutter, astrophysicist and the one and only Agent to the Stars (http://www.pmsutter.com).
All Episodes | Support | iTunes | Google Play | YouTube
EPISODE TRANSCRIPTION (AUTO-GENERATED)
Let's face it. The speed of light is weird. And like most weird things in the universe, the more you think about it, the weirder it gets until you reach a point where the weirdness is so overwhelming that you just stop thinking about it altogether and go about your life pretending that the whole thing never happened. But here we are, you and me, and we're going to think about the speed of light a lot. And it's going to get weirder and weirder as we go.
And at the end of this episode, nobody will be satisfied. You won't be satisfied. I won't be satisfied. We'll be left with a half hour of thoughts and ramblings that seem to be building up to something only to lead absolutely nowhere because, and I'm telling you this to save your sanity now, we have basically no idea what's going on. Like I said, the speed of light is weird.
So let's get weird. Let's start with the number itself. The speed of light is defined to be 299,792,458 meters per second. Wait a minute. Defined?
Defined? Seriously, defined? The speed of light is defined to be a certain number? How does this even work? Isn't the whole point of science to sit there and listen to the whispers of our mother nature and not run around telling her what to do?
Who are we? Barely sentient apes on some poduct planet orbiting a very boring star in some random spiral galaxy to tell the electromagnetic force how fast it should propagate? Well, yeah. Why? Because the number doesn't matter, folks.
It doesn't matter. I'm repeating myself a lot in this episode, and I don't care. It doesn't matter. Yes. The speed of light is an important number, which is why I'm talking about it in this episode, but the actual numerical value of it doesn't matter.
Why? Because it has units. It has dimensions. It's a number in a particular reference system. Imagine talking to an alien, like, finally, we make contact with ET.
They visit us or we visit them or we exchange telegrams. And we say and we're checking our notes on science to see how developed and smart they are, and they're sending us notes, see how smart we are and say, by the way, we have measured the speed of light to be 299,792,458. And the alien will say, after appropriate translations, Oh, 299,792,458 of what? And we have to respond, oh, it's a speed. You know?
A speed. Like, you're running down the road or driving in your car. You have a speedometer. It tells you your speed. Light has a speed.
Light travels at 299,792,458 meters every second. So if a second goes by, this is how many meters it will travel. Okay. And then the alien responds, thinks about it for a little bit, mulls it over, translates, gets back to us, and said, so okay. What's a meter?
And, what's a second? And so we have to come back. And once we start trying to define, a speed of light, we have to define a meter in a second. So we have to respond with this. Oh, well, you know, when you get down to it, a meter is a certain fraction of the Earth's circumference, and a second is a certain fraction of the period of the Earth's orbit.
And then the aliens come back and say, okay. What's in Earth? Do you see how absurd this whole thing gets once you introduce units into it? As soon as you start to define a number like the speed of light based on other things like the meter and the second, you realize it's all just made up. In other words, the numerical value of the speed of light doesn't matter.
It could be 299,792,458 meters per second. It could be 323 gargopllexes per singc rats. It could be 6.7 times 10 to the eight miles per hour, wherever the heck that mile is. It could be one. A lot of physics, especially high energy physics and astrophysics just sets the speed of light equal to one.
One? One what? One speed of light unit. It doesn't matter. The number doesn't matter.
It's meaningless because it's attached to units, and the units are all made up and totally arbitrary. I'm not just being facetious here trying to play word games because the speed of light is a speed. That's the important thing. It's a relationship between distance and time. The speed on your car when you're driving tells you how far you can travel in a certain amount of time.
It's a relationship between speed and time. So the speed of light is a relationship between speed and time. In order to define the speed of light, you have to define the distance and the time that you're talking about. You have to define that relationship. So the speed of light that comes out is based on your preexisting definition about the relationship between space and time.
The speed of light and the unit system you use to mark that speed all have to go together. So one way is to define what a meter and a second are, which are totally arbitrary and made up, and then you can get the speed of light. But it's just as arbitrary to define the speed of light itself, and from there, you can figure out what the meter and the second are, and that's exactly what we've done. We've defined the speed of light to be a specific number because the specific experiments to measure the speed of light, we can just as easily talk about experiments to measure the length of the meter or experiments to measure the duration of the second. They are all the exact same thing, and we're just going about in different ways.
Are you feeling weird yet? Good. It's arbitrary. The speed of light is arbitrary. It's a made up number.
Who cares? But it except all of us care. We care about the number. Why? Because we care about light.
And we care about lengths, and we care about time, and it seems kind of important. So how do we go about measuring the speed of light? Okay. It's arbitrary and made up, but it's still a number we'd like to know. We'd like to know how long a meter is.
We would know like, know how long a second is. We would like to know how fast the speed of light is. Light plays a somewhat important role in our lives, and we would like to measure it. The first step is realizing that it does indeed have a speed, which is not immediately obvious because it's pretty dang fast. You flip the switch, and, bam, there is light in your eyeballs.
And our ancestors thought it was so it's so fast. They thought it was instantaneous. It's like, could you possibly blame them for thinking otherwise for not thinking otherwise? It's light just happens. First, you have no light, and then you have light.
Then a, an astronomer by the name of O'Romer in the late sixteen hundreds had to go and measure something, and he had to figure out the light does have a finite speed. And he was especially interested in the orbit of Io around Jupiter. Why that particular moon? Well, it's the easiest to see. It's the fastest one.
You get a lot of orbits of Io in because it's the closest to Jupiter. So you can see a lot of orbits of IO compared to orbits of the other moons, and it's a bright moon. It's a bright planet. This is a thing to look at in the sky, especially if it's the 16 hundreds. They've got nothing better to do.
Sometimes Jupiter eclipses Io. Like, it blocks that little moon from our view. And when we wait patiently and stare, Io will pop back out from high Jupiter. When I was reading the descriptions of these observations, I was imagining, like, a kid hiding behind their parents' legs. Like, oh, they see you coming, so they duck behind their parents' legs, and then you feel, wait a while, like, they start to poke their head out.
Like, they're a little bit. They're shy but a little bit curious. I imagine that's Io around Jupiter. So sometimes Io ducks behind Jupiter, and we can't see it, and then it pops out the other side. And these pop outs should happen at the same interval every few days because nothing is messing around with the orbit of Io or Io's orbit is Io's orbit.
It pops behind Jupiter and pops back out, and and you can count the days between them, but they do change. The time between these pop outs, between these eclipses changes. Sometimes they are a few minutes late and sometimes they are a few minutes early. And by the late 1600s, we were able to measure this accurately enough that we could see that something funky was going on. One explanation is that something is is indeed messing with the orbit of IO.
I mean, who guaranteed that IO should have a regular steady orbit? But that seems a little bit weird, especially once people like Romer made the connection that it was tied to our own orbit around the sun. See, when we were in the point of our own orbit when we were approaching Jupiter, the pop outs, the eclipses, they were getting a little bit shorter than average. And when we're in the point of our orbit, when we happen to be moving away from Jupiter, the pop outs were coming a little bit later and later. So, why should Io, this moon of Jupiter, why should it care about our position around the Sun at all?
Romer cracked the code after enough observations. If we happen to be in a certain position in our orbit and we see a little pop out of Io, Io pops up, finishes in the eclipse, and it's gonna start its another round, by the time another pop out happens, say, a few days later, we might be we'll be in another spot in orbit. We'll have moved, and maybe we're a little bit further from Jupiter than the last time we saw a pop out. In this case, we have to wait for the normal pop out time, which is just the normal motion of Io around Jupiter, plus the additional time it takes for the light to reach us since the last time we saw it. We've moved further away from Jupiter, and so that event has happened, but now we're further away, and that light has to travel an extra distance, and it looks like the pop out happens later.
And if we're a little bit closer to Jupiter than last time we saw a pop out, then the light will reach us a little bit faster. It doesn't have as much distance to travel to reach us. We see the pop out earlier. Based on these arguments, Romer was able to estimate a speed of light that was about 20% off than our current value, but, you know, it's all made up anyway, these numbers. Obviously, there were a lot of controversy around his observations.
They weren't that great. He couldn't apply it to the other moons. It it wasn't perfect, but, in general, Romer, Ol' Romer, is credited with being the first person to measure the speed of light. After centuries and centuries went by, we had a lot more measurements, including direct measurements where we're bouncing laser or light off of mirrors, and we're able to directly measure its speed, and we could finally pin it down. And, yes, it did indeed turn out that light has a finite speed.
And you can measure it too in your very own kitchen. But to understand why, we have to go to mine, and therefore everybody else's, favorite nineteenth century bearded genius, James Clerk Maxwell. It's been a while since I got to talk about him, and I'm happy to do so again. The eighteen hundreds were a crazy time for all of science, especially physics. I mean, if you think our modern puzzles of the unification of the forces and dark energy and all that are driving scientists nuts today, you should see the notes of the folks from the nineteen hundreds, especially when it came to electricity and magnetism, which were so weird.
The phenomena of electricity and magnetism were so weird and beyond description that nobody could do it except in little bits and pieces of experiments here and there going over decades. Like, someone figures out some little bit of electricity and they're blown away and they're doing public demonstrations and wowing people, and people think that it's witchcraft. And think that it's witchcraft. And then twenty years later, someone does something about magnetism, and everyone's blown away again. And no one it just doesn't make any sense.
And it's an awesome story that I will tell in a future episode. The growth of our understanding of electricity and magnetism is hilarious over the course of the 19 hundreds and can teach us a lot of things about our current state of knowledge when it comes to things like dark matter, dark energy. But I'll spoil the ending right now. James Clerk Maxwell and ESLU use use his full name every time. Stop.
Try. Stop me. Took all the bits and pieces and experiments and thoughts done over the course of decades and collected them into a single unified framework, describing all of electricity and magnetism. He was able to write down four equations. He originally wrote down a bunch more, but now we have notation mechanisms that allow us to compact it.
He wrote down four equations that described all of electricity and magnetism, which is a little bit weird at first. Like, the the electricity flowing through your electronics is described by the exact same equations as the magnet sticking to your fridge? Yeah. That was a surprise. No one really expected that, but, you know, James Clerk Maxwell is a genius, and so he he was able to do it.
He had one framework that described all of electricity and magnetism. And his big idea, the big thing that came out of this, after all this work, all the decades of experiments and the mathematics and the genius, what came out was that he invented Patreon. Patreon.com/pmsutter is how you can keep this show going and all of my education outreach activities. And there is a little special thing going on. I am doing giveaways of signed copies of my book, How to Die in Space.
It's coming out in June 2, and you can get an autograph copy if you sign up on Patreon. Thank you, James Clerk Maxwell, for inventing Patreon. The big idea that he found was that a changing magnetic field can create an electric field, and a changing electric field can create a magnetic field, and they can leapfrog over each other. So if you can start waving some electricity, however you want to do that, they'll generate some magnetic fields, and those magnetic fields will be waving. And then those waving magnetic fields will make their own waving electric fields, which will make their own waving magnetic fields, and they'll go back and forth and back and forth and back and forth.
And they push like waves across distances, just like ocean waves or waves on a slinky, except they're made of electricity and magnetism. James Clerk Maxwell was very curious about these electromagnetic waves, and he went about calculating the speed. Like, wow. There's a wave. I wonder how fast it goes.
It is determined by how effectively or how easily electric fields travel through space, called for the nerdy the permittivity of free space, and by how easily or effectively magnetic fields travel through space. Also for the nerdy the permeability of free space. So this isn't, like, that surprising. You have waves of electricity and magnetism. How easily an electric field pushes itself through space and how easily a magnetic field pushes itself through space will tell you how easily an electromagnetic wave will travel through space, what its speed is.
And he slapped these together. These were known constants. You can get these for measurements, and he got the speed of the wave, and it was the speed of light. And that's when James Clerk Maxwell realized that he had invented light, that light is electromagnetic radiation. It's waves of electricity and magnetism.
Of course, now in the twenty first century, we know that this isn't always true. Sometimes you need other descriptions to describe light, but that's his own thing. So how can we take this knowledge that light is made of electromagnetic waves to measure its speed directly? Well, all waves, every single wave you're ever going to encounter in your entire life, including the sound waves that are hitting your eardrums right now, have a defined relationship between their speed, their wavelength, and their frequency. Wavelength is the distance between a crest of a wave and the crest of the next wave.
Well, the length of the wave. It's it's, you know, pretty self explanatory. The frequency is if a wave is washing over you of how often the peaks come. So if you're standing on the beach and you have ocean waves crashing into you, how often they come is the frequency of those waves, and then the distance between those peaks is your wavelength. If you multiply the wavelength by the frequency, you get the speed.
So to measure the speed of light, you need to measure its wavelength and its frequency. If you can get those two numbers, you can get the speed, and you can use a microwave oven. Seriously, try this at home, and I'm not being sarcastic. You can actually try this at home. Take your microwave and take out the plate that does the the rotating thingy to evenly cook your food.
Take take that out. That will spoil the experiment. A microwave oven is a cavity, a space filled with electromagnetic waves, filled with microwaves, hence the name microwave oven. To get the frequency, it's printed on the back or in the manual. It'll tell you the frequency because it's got a little device in there that generates electromagnetic radiation, and it generates this by pushing electrons around at a certain frequency.
So that's in the box. You know that. You can just write that down. But we still need the wavelength. We need to measure the distance between peaks.
So what you do is you get a bunch of paper towels, and you get them wet, and you stick them in the microwave. Make sure you've taken out the turntable, and you turn it on for a while. And what you'll see, some parts of the towel, the paper towel, will dry out and maybe even start crisping up and burning if you leave it in too long, and others will stay wet. What you're seeing are the electromagnetic waves. You can't see them with your eyeballs, but the electromagnetic waves are the things doing the heating inside a microwave oven.
And there's gonna be places where they peak just like a wave peaks. A water wave peaks or a sound wave peaks, and there's gonna be places where there's not so much wave going on. Yeah. You stand on the beach. Sometimes there's a wave slapping at you, and sometimes there's not a lot of water at all.
That's the whole point of a wave. And so inside that microwave oven, there are some places where there's a lot of microwaves happening all at once and then there are other places where there's not so much microwaves happening all at once. What you're seeing is the wave right there. The imprint of the wave inside your oven. This is why we have the turntables because there's places fixed where there's going to be a lot of electromagnetic radiation, a lot of microwaves, and places where there's not so much.
And so the turntable rotates your food around those places so it gets nice evenly heated. But you can take your, paper towel out and you can measure with a ruler the places on the paper towel that got cooked. Measure the distances between the peaks of the wave. Multiply that by the frequency on the outside of the box and you'll get a speed. And guess what?
You're gonna get the speed of light. But what's so special about this speed? Why do we care? It's just a number. Right?
It's like the speed of sound in air. Like, yeah, we care about the speed of sound in air because we live in air and and we have lots of sound based applications, and we like to know what's going on. It's a useful number. But the speed of sound is just based on some properties of air, like the density and the temperature. Who cares?
Why is it a big deal? It's a big deal because Einstein said the speed of light is a big deal, and Einstein is a big deal because he said the speed of light is a big deal. In other words, the speed of light isn't just a random number that you calculate and then put away. No. It's a number that everybody cares about.
It's special. It's weird. I did a couple episodes on special relativity a few years ago, so I won't get into the whole sordid mess again. But the gist is that Einstein discovered that space and time are unified into a single complete fabric. You know, space time.
There's just one thing. We live in a four dimensional universe, three dimensions of space, one dimension of time, space time. But space is space, and time is time. These are two different things. You measure space with meters.
You measure time with seconds. How can you put space and time on the same footing? How can you weave them into the same fabric if they're made of different things? Space is a very spacey thing, and time is a very tiny thing. How can we make them equal?
Well, we need a conversion tool, an exchange rate, a way to connect measurements in space to measurements in time. Like, if I wanna put space and time right next to each other or perpendicular to each other or in the same fabric in the four same four dimensional setting, I need to know. How much is one meter of space worth in seconds? Is it worth ten seconds? Is it worth fifty seconds?
Is it worth point one second? Is it worth a microsecond? Is it worth a hundred trillion seconds? How much is one meter worth in seconds? I need to know this conversion.
I need to know how to connect space to time and time to space. I need to translate in special relativity, Einstein's relativity, which is where we get this language of space time, we get a constant, a number. Let's call it c because c is short for constant, And this constant appears in special relativity, and it tells us how much one meter of space is worth in seconds and vice versa. It tells us how to translate back and forth between space and time and time and space. This constant has to have units of speed because speeds are the things that relate distances to times.
You know, again, if you're in your car and you're going 60 miles an hour and if you don't know what a mile is, don't worry. It's a unit of distance. If you're going 60 miles an hour, it'll tell you that for the cost of one hour of time, you will get 60 miles of distance, or vice versa. At the cost of 60 miles of distance, you have to exchange that for one hour of time. This constant c that appears in special relativity tells us how the universe connects space and time.
Like, what's the fundamental way for space to connect to time? How does the universe do it? What what speed does the entire universe operate at? Special reality relativity itself says that there has to be this constant, this connection, this glue, this conversion that lets us translate between space and time, but it doesn't say what that number is. It doesn't give a value.
It just says, yes, this constant exists. And you think we might be stuck, but it turns out that there's a clue in Maxwell's equations. It turns out that Maxwell, when he was writing down his equations of electromagnetism in the 1860s, was already writing down a proto theory of special relativity. He had no idea he was doing it, but he was making a modern twentieth century, twenty first century theory without even realizing it. Maxwell's equations like, special relativity, it's almost like a metatheory of physics.
It tells you how theories of physics need to operate, how they need to look. They need to play in this four dimensional space time setting. Maxwell's equations were already there. They already played in this four dimensional setting. That wasn't true of other laws of physics that we had at the time or other theories.
It wasn't true of Newton's theories. It wasn't true of statistical mechanics or anything else at the time, but it was true about Maxwell's equations. And when you merge Maxwell's equations with special relativity, you realize that the c, this constant in special relativity that just appears is the exact same thing as the speed of light. Now we understand the true ultimate weirdness of this. This is the speed.
The speed of light is the speed that connects space to time at a fundamental level. It's the maximum possible speed in the universe. It's the speed that the universe uses to translate between space and time to allow them to be in the same four dimensional setting. This maximum possible speed can only be achieved by massless things, and waves of electricity and magnetism are indeed massless, and so the speed of light just so happens to also be this maximum speed. Special relativity doesn't care about light.
It doesn't know about the existence of light. It just so happens that light fit the bill to be this special number. Special relativity has nothing to do with light. The speed of light has nothing to do with the speed of light and yet has everything to do with light because without Maxwell's equations, we wouldn't have been able to calculate that number. So light does hold a special place.
It's not like the speed of sound. The speed of sound is just a number. It comes out of some calculations, properties there, and then you forget about it. The speed of light comes out of some calculations, some properties of electricity and magnetism. When you put it together, you get a number.
Okay. And then you also realize it's a cornerstone of how the universe works. In other words, the speed of light is weird. Speed of light doesn't matter. The number doesn't matter.
The value doesn't matter. It's just something you can measure in your free time if you feel like it, but it also just so happens to be this fundamental constant, and it connects and unifies space and time. But why is it this number and not something else? Once you pick how long a meter is and how long a second is, you get a number of the speed of light. Why is it another number?
Here's something weird. It can't be anything than exactly what it is. The speed of light is fundamental. It appears in special relativity. It appears in Maxwell's equations.
It's an important number, but it has units so it's an arbitrary number. But in total, complete, confusing weirdness, its value is already chosen. It's already fixed. It's already known. Let me explain.
In physics, we care more about dimensionless constants, ones that are just bare numbers, not related to kilograms or meters or joules or seconds or anything else, just numbers. Speed of light is important, but it's not really super duper fundamental because it's also attached to a unit system. There are other numbers that appear in physics, in our theories, in our experiments that aren't attached to any unit system. For example, there's something called the fine structure constant. Someday, I'll do a very own episode on the fine structure constant.
Please feel free to to ask. But for now, I'll just say it's perhaps the most important constant in all of physics, and it appears everywhere. To get the fine structure constant, it's built out of a combination of other numbers, Planck's constant, the elementary charge, the electric constant, and the speed of light. You mush these numbers together and you get something we call the fine structure constant, which is approximately equal to 0.007297 and a few other digits. We know it to about one part per 10,000,000,000.
Just a number. It's not point zero zero seven centimeters or point zero zero seven meters per second or point zero zero seven joules per meter squared. It's just point zero zero seven, double o seven. It's just a number. Like talking to an alien, when we figure out, oh, hey.
We have this thing called the fine structure constant. It appears in this, these kinds of calculations. They say, oh, yeah. We got one of those too. And they say, okay.
What's your number for the fine structure constant? We say point o o seven. You know what the aliens will say? They'll do their translations. They'll convert, though, to their own numbering system.
They'll say, yep. That's what we get to. That's the end of the conversation. Point o o seven. The universe can agree on that because it's not attached to a number system.
That's a much more fundamental constant. It can only be determined or measured by experiment. It doesn't come out. It appears in physical theories, but we can't predict its value, or it's very difficult to predict its value without a lot of experimentation. And here's the thing.
The speed of light can't be anything other than what it is because the fine structure constant is exactly the way it is. If you wanted a different speed of light, you need a different fine structure constant, and we can't have a different fine structure constant because it's a constant of nature independent of any unit system. This is exactly the way the universe is, so the speed of light is forced to be that value. You know, imagine if you have a cheese plate. I come out with a cheese plate.
I say, here's the cheese plate. I got three cheeses. I picked it for you. You got a brie. You got a nice Irish cheddar.
You got some gorgonzola. This is it. This is the cheese plate. This is the fine structure. Constance made out of other things.
It just is. It just exists. And you say, no. I don't want the gorgonzola. I want something else.
Well, you can't get something else because this is the cheese plate that I gave you. If you wanted to swap out one of the cheeses, it'd be a different cheese plate, and that's a different universe. We don't live in that universe. We live in this universe with this cheese plate. We live in this universe with this fine structure constant point o o seven and a few other numbers and nothing else.
And because the fine structure constant is fixed and independent of any units in any us, an alien intelligent civilization, we can all agree on this number. And because the speed of light is a part of that, goes into that calculation, we can't have any other speed of light than exactly what we have. So on one hand, the speed of light is completely and totally arbitrary and made up. It's just random number. It's dependent on the unit system.
It's totally arbitrary. On the other hand, its value is exactly what it is, and we have absolutely no choice in the matter, and it's determined by something else, the fine structure constant. And why is the fine structure constant exactly the way it is and nothing else? Well, we don't know. I told you at the beginning that at the end of this episode, you would not be satisfied.
And I hope I've delivered. And also, this is all very weird. I'd like to thank Robert h on email, Michael E on email, at Desiran ninety four on Twitter, Evan w on email, Harry a on email, @twwdickson on Twitter, Harry p on email, Colin e on email, and Lothian fifty three on Patreon for the questions that led to today's episode. Also, I can't forget Patreon, patreon.com/pmsutter, and my top contributors this month, Matthew k, Justin z, Justin g, Kevin o, Duncan m, Corey d, Barbara k, Nudredu, Chris c, Robert m, Nate h, Andrew f, Chris l, John, Cameron l, Nalia, Aaron s, and Kirk t. Wow.
I can't thank you guys enough. All of you, the incredible community of listeners. If you if you can't contribute to Patreon, go to iTunes, leave a review, tell your friends about it. I really appreciate it. But, hey, I am doing giving away signed autograph copies of my new book, How to Die in Space.
It's coming out 06/02/2020. I am doing signed giveaways on Patreon. Go to patreon.com/pmsutter. You sign up at the right level. You you pledge at that level for three months, and then, voila, a signed copy of How to Dine Space appears in your mailbox.
How awesome is that? Keep sending those questions. Hashtag ask a spaceman. Ask a spaceman@gmail.com. You can follow me on all the social channels at paul matt sutter.
You can check out the show on YouTube where I flail my arms around as I'm talking about this stuff. And I'll see you next time for more complete knowledge of time and space.