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Hey, welcome to Sign Stuff reproduction of iHeartRadio. I'm Horrid cham And in this year end episode, we are answering the question why is a year a year? Why do we have three hundred and sixty five days in the year? Is it changing? And will the new year always be the same? This is the second in our two part holiday special, so be sure to check out last week's
episode about whether the North Pole is moving. Today, we're going to continue our conversation with my friend and planetary scientist Matt Siegler, and he's going to fill us in on the physics of our annual spin around the Sun. So get ready to count down the new year with Science as we answer the question why is a year a year? Hey? Everyone, Happy new Today we're celebrating another orbit around our lovely Sun and the end of our first year on Science Stuff. On behalf of everyone involved
in the show. Thanks for tuning in to get you into party mode. We're going to continue my conversation with planetary scientists doctor Matt Siegler. Doctor Siegler is a professor at the University of Hawaii's Institute for Geophysics and Planetology, and he works with NASA and the European Space Agency
on several missions. On our last episode, we talked about how you can't really trust the North Pole no matter if you're talking about the magnetic North Pole, the spin axis of the Earth, or even the GPS top of the world. It's all changing. So I wanted to ask doctor Siegler if the same applies to the year, as our orbit around the Sun changed since the Earth was formed, or will it change in the future. Here's my chat
with doctor Siegler. Okay, let's stitch over to the new year. Matt, are you looking for to the new year?
Oh? Yeah, it's a very exciting new year.
You sound excited. Did you do anything specially in Hawaii for New Years?
Apparently there is a massive, massive home fireworks display world that goes on here such that it becomes kind of out of control and chaotic where the skies are just lit up.
Well, good luck with that. So I thought it'd be fun to talk about in the Solar System whether the year has changed for Earth and also where are the years like in other planets. So let's start with the planet Earth. We talk about how the north pole is changing on Earth. Is the year changing for planet Earth also? Or is it pretty constant?
Yeah, the year is not really as malleable as the spin axis. In a way, the year is how long we go to take one revolution around the Sun, Okay, and so that period ends up being pretty constant. You know, we talked about how oval the Earth's orbit is, but it's still take the same period to go around. It will just go faster at some parts of it and slower at other parts.
Okay, here's what's going on. The Earth's orbit around the Sun is pretty much a circle. If someone showed you a picture of that orbit, you'd probably say, yep, that's a circle. But actually it's not quite a perfect circle. It's a little bit about one point six percent ovalish or elliptical. And this has a few interesting consequences. First of all, it means we're not always at the same distance from the Sun. In January, we're about three million
miles closer to the Sun than in June. Now, that doesn't affect too much how hot it feels on Earth. As we'll talk about later, the tilt of the Earth has a bigger effect on the seasons. But it does mean that the Sun looks a little bit smaller in June than in January, about three point three percent smaller. And it also means that our speed around the Sun changes throughout the year. In January, the Earth is swinging around the Sun a little faster than in June, about
two thirds of a mile per second faster. So if it feels like the holidays in New Year go by fast, you can blame it on the earth slightly elliptical orbit. Okay, now the question is how did we get that orbit? I have two questions. The first question is what determined how long our year was going to be? Is it tied to the formation of the Solar system.
Yeah, so, as the planets formed, they had a certain time period over their orbit. And there is actually a really interesting story about that that we think the way the planets formed, Jupiter and Saturn were at slightly different distances to the Sun than they are today, and that actually ended up with them going into a resonance, which is every one time Juwber goes around, Saturn goes around
twice or something like that. Right, And so what happened then was that the gravity of the two giant planets would yank on you each other, and that eventually caused Saturn to move around and then slingshot out into the outer Solar System, and that messed up Neptune's orbit and fired it kind of out into the Coiper Belt and may have knocked around all these icy objects out there and caused them to go haywire and fall into the inner Solar System, and some of them hit the Earth
and Moon and Mars. And that might be one of the main reasons we have water here on Earth is because of this chaotic change of years.
Yes, scientists don't really know why we have so much water here on Earth. Some of the water in our oceans and lakes probably came from water that was trapped inside the Earth when the Earth formed that was then burped out into our atmosphere by volcanoes. But that's not enough water to fill up the oceans. So scientists have a theory that the rest of the water on Earth came from space, from icy comets or astero It's from
the far out Kuiper Belt in our Solar system. And what doctor Siegler is saying is that the reason that water ended up here to create deep oceans and maybe life and us was the orbital Shenanigans of the planets Jupiter and Saturn. So as you look back and give thanks this holiday season and New Year, be sure to give a shout out to the planets Jupiter and Saturn for putting us here. Now, could that have happened to us here on Earth? Were we thrown into this orbit
in that crazy chaotic young Solar system? Sort of? Actually our planet came about from two smaller planets crashing into each other. Could that have happened to Earth? Could something have happened to make us have a different year in our past? Or can it happen in the future.
Yeah, And so this is something we're learning from studying other Solar systems or exoplanets, right, is that a lot of the planets seem to migrate around closer or farther away from their star over time. And so I think the ideas that the Earth has not migrated a ton over its time. But the Earth we think formed kind of like a pre Earth that was a little bit
smaller than Earth. And then there was another planet about the size of Mars that crashed into us, and most of that material became the Earth, but some of it got thrown into a disc kind of like Saturn, and that formed the Moon.
Oh so the pre Earth could have had a different orbit, could have had a different year.
Yeah. Yeah, So you had these two planets that one was a little closer to the Sun than the Earth and so it had a shorter year, right, and then one was a little farther from the Earth and had a longer year.
Uh huh.
And they got into some kind of gravity tug of war and crashed into each.
Other, and that's when the year was born. Yes, that's when the Earth year was born. Oh before that, there was no Earth year after that impact. Now the year was born, yes, when it just happened forzero point five six billion years ago, not yesterday. No, And we can tell when that started because the rocks on the Moon that formed at the same time haven't been all messed up by weather, and so we can date a rock from the Moon and figure out how old the Earth is. Whah.
That's fascinating. And we don't think it's changed since then, Like the Earth year hasn't changed much.
No, I mean there's some perturbations to the year from how much Jupiter might yank on us and alter our orbit a little bit, right, pull us out a little towards Jupiter. Venus might pull us in a little bit. But on average, the year has not changed substantially.
I see it has changed, but just a little bit. Yeah, and what do you think is going to happen in the future. I think we're going to be stuck with our year for quite a while. Actually this is not quite true, Doctor Sieger says. There is something that is going to affect how long our gear is going to be in the future. So when we come back, we'll talk about what that effect is and how other orbital effects are going to fundamentally change how we celebrate the
new year. So don't say goodbye to the old year just yet.
Stay with us.
We'll be right back. Hey, welcome back. We're talking about the physics of the new year, and so far we've learned the Earth's orbit around the Sun is not a perfect circle, and it's the result scientists theorize of two planets crashing into each other. But once the crash settled and the debris became the Earth and the Moon, our orbit around the Sun has been pretty stable. But that's not always going to be true.
I guess in the long long future, roughly three or four billion years from now, the Sun have expanded enough that the outer atmosphere of the Sun will cause some drag on the Earth and that might cause it to lose a little bit of its momentum. Huh, and then it would slowly spiral down.
In into the Sun. Yeah, so the year will get shorter and short. Well, first of all, like, if we're being dragged by the atmosphere of the Sun, we're probably not here, like we're cooked.
Yeah. Yeah, so hopefully we're all living somewhere else.
We might see the Earth's year get shorter and shorter as it drags into the Sun.
Yeah. And it's kind of questionable or depending on what model you might assume of how a star expands, whether it's enough drag to cause the Earth to spiral in all the way, or if it just slows us down a little bit and we end up a little closer to the venus or crash in the venis sudden. I guess we won't see, but we can imagine that there are some interesting ways.
Hopefully we'll see from a distance.
Yeah.
So the idea is that the long term of our solar system is that the outer atmosphere of the Sun will expand away. There'll be a white dwarf star, you know, where the core of the Sun that remains is. And I suppose the Earth will be a little closer, probably because of this drag, and have a shorter year, but hopefully there will still be some hulk of what used
to be the Earth going around there. And whether after that it can never be a place where life could re emerge, that's going to be an interesting, big question, I see. But going through the outer atmosphere of the Sun will be a traumatic period for.
The Earth, meaning there might not be anything alive to celebrate New Years.
It's hard to do a sad one.
That's pretty good. So the year will get shorter, according to scientists, maybe a few billion years in the future when the Sun expands and engulfs the Earth, making it into a smaller orbit. Now, in general, the orbit of a planet depends on how close it is to the Sun. Planets close to the Sun move really fast and their orbits are short, and planets that are far from the Sun move slowly and their orbits take longer. For example, mercury is the closest planet to the Sun, and its
orbit takes eighty eight Earth days. In other words, a year on Mercury is only eighty eight days long. But Neptune, the farthest planet from the Sun, has an orbit that takes around sixty thousand Earth days or about one hundred and sixty three Earth years. So if you want it to feel younger or older, you could just move to another planet. I'm just trying to find a way to make myself younger.
Yeah. Well, if you measure it by years, then you want to go further out in the source. Right, So we have Mercury is close to the Sun and so it's year is only eighty eight days long. Uh huh. Yeah, so you might feel pretty old pretty quickly if your birthday is every three.
Months, as opposed to if you move to like Saturn.
Yeah, you go out to Saturn and your year is about thirty Earth years, right, so you're barely a year old and Saturn, yeah.
It'd be like one and a half basically.
Yeah, so there you're a Saturnian infant.
Oh my goodness. Okay. There are two interesting things about the physics of the New Year. The first is one that most people know, and that is that the orbit of the Earth is not quite three hundred and sixty five days long. It's actually three hundred and sixty five days, five hours, and forty eight minutes, Meaning the Earth doesn't spin in place a full three hundred and sixty five times in the time it takes to go around the Sun and back to the same spot. It spins a
little bit more. But we celebrate the new year when we fad three hundred and sixty five days, which means the new year we celebrate is not actually how long it takes to go overround the Sun, and we build up this difference for three years until every fourth year we add a whole new day to the year on leap years, So if you really wanted to celebrate going around the Sun a full orbit, you should wait until about six am on New Year's Day to set off
those fireworks. The other interesting thing about the physics of the new year is that the new year also doesn't celebrate the passing of the seasons. We're used to thinking that a year is when we've had a full cycle of winter, spring, summer, and fall, but actually our orbit and the seasons are slowly going out of sink.
We celebrate New Year's conspicuously around the winter solstice, right, but those events have changed where they would fall in the year over time.
Because of the wobble of the spinactive of the Earth. Yeah, all right, this one's a little hard to explain. Right now.
We celebrate the New ye near the winter solstice, which is the longest night of the year for people in the Northern hemisphere, and it's the longest night of the year because that's when the northern hemisphere is tilted the most away from the Sun. Then six months later, when the Earth has gone through half of its orbit, the northern hemisphere is tilted the most towards the Sun, making it the longest day of the year for people above
the equator. This is called the summer solstice, and right now, those two solstices fall on December twenty first and June twenty first. But as we talked about in the previous episode about the North Coal, the Earth is wobbling, which means its spin axis is rotating and changing direction, sort of like a top that wobbles as it spins on
a table. Scientists think that in thirteen thousand years, that wobbling is going to make the Earth tilt in the opposite direction, which means the winter and summer solstices are going to switch. In thirteen thousand years, the summer solstice is actually going to be on December twenty first, and the winter solstice will be June twenty first. In other words, in thirteen thousand years, those of us in the Northern Hemisphere are going to be celebrating New Year's Day in
the middle of summer. It's going to be hot, and at least in the United States, if the United States still exists in thirteen thousand years, we're going to be celebrating the fourth of July in the dead of winter. And that's because the seasons follow the tilt of the Earth, and the tilt of the Earth is changing regardless of our orbit around the Sun.
Earth has a round enough orbit that the electricity of the Earth's orbit is not a predominant cause of season. I see, yeah, so it's mostly just this tilt.
But that's wobbling. So that means that in like ten thousand years, it's going to be summer in New Year's Yes.
If you're in the northern hemisphere, what so everyone will be like Hawaii.
So our year is not really defined by the seasons.
Yeah, seasons will slowly drift over thousands of years time scales, thirteen thousand year time scales, right, it will change. Oh so yeah, So that's why I don't know when we talk about stoneheads being aligned for the summer solstice, I think maybe it's not aligned in the same way as it was when they built it.
What does that mean? It means New Year's Day is totally unrelated to the seasons.
Yes, in the long game, New Year's Day is totally unrelated to the season.
It's also arbitrary and changing at the same time. Yes, these things we think are like, you know, set points in our lives, in our cycle of society are really in the long run due to physics changing.
Yeah, or due to culture.
You know, that's wild.
Yeah, nothing is fixed.
You can't trust anything. Man, Just live with the impermanence. He live in the moment. Just enjoy the holidays.
Yes, okay.
So to recap, the length of the year that we have right now on Earth is the result of a gigantic crash that happened billions of years ago that merge two small planets together and put them in a single orbit around the Sun. That orbit is pretty constant. The length of the year is not changing, even though the orbit is not a perfect circle, and we move around the Sun at different speeds at different times of the year. But what is changing is the tilt of the Earth,
which is what determines the seasons. So in the future, we're going to be celebrating new Years in opposite seasons from how we celebrated today. People in the northern hemisphere will celebrate it in the middle of summer, and people in the southern hemisphere will celebrate it in the middle of winter. Case it's still a celebration of surviving another spin around the Sun plus or minus five hours and
forty eight minutes. All right, When we come back, we're going to recap our favorite episodes of the year, including which one surprised me the most and which one was the most fun to make. So stay with us, we'll be right back. Hey, welcome back, Okay. In this third segment, I thought it'd be fun to recap some of our favorite episodes of the year. In twenty twenty five, we made forty three episodes on a wide range of topics. We asked questions about animals, like do our pets lie
to us, can animals appreciate music? And do animals have consciousness? We wondered about space topics like what's inside a black hole? Or where are all the aliens? And can we terraform mars? We also explored questions about technology like what is a quantum computer? Can we upload our brains to the cloud? And can you survive being cryogenically frozen? And we answered questions about evolution and the human body and brain like
why do we have five fingers? Do we have to wait thirty minutes after eating before you can go swimming? And it is food coloring that for you? I could go on and on. So if you haven't gone through our archive in a while, I encourage you to go check it out. I guarantee all the episodes are fascinating. To pick which ones to recap, I ask the people who work on the show to pick their favorite episodes. So first up is our sound mixer, engineer and general
manager of the show, Casey pegram. Casey is the reason I and every guest on the show sound great. And believe me, we're recording pretty suboptimal conditions most of the time. So the fact that the show stays on track and sounds like it was all recorded in the studio. Is all thanks to his magic. Back in October, Casey picked this episode as his favorite Don't pull the plug and get ready to live inside our electronic mind as we answer the question can you upload your brain to a computer.
So, the idea of mind uploading, which is like a hypothetical future technology, is that if you make a simulation of the human brain, and you make it refined enough, it will be as good as the real thing. And the hope is that if it's good enough, we can use this technology to migrate over to machines.
Yeah, it's in principle possible for you to capture that level of detail from a human brain. We do it from animal brains all the time. Unfortunately, those methods.
Require that you die.
We don't yet have wadys of looking at it without taking chunks of your brain out, essentially pickling them and then slicing them into.
Very very thin sections of brain. But what you're getting is the instant after you had actually died. So I don't think you would want to be necessarily preserved in that state, right.
Casey said he found this episode interesting because of the topic and the viewpoints of the three interviewees. In the episode, we talked to a philosopher, a mathematician, and a neuroscientist, all interested in the idea of uploading your brain. Casey said he liked that it had a great mix of sci fi and philosophy, and that it's speculative but at
the same time very plausible. You also liked the third interview covered the exact main objection he had about uploading your brain, which is that the copy you make of you is not going to be a part of you, even though it may think it is.
So why would anybody think that if we build a simulation of your brain, then somehow you enter the simulation instead of staying there where you are in your brain.
I see, but yeah, that's not you, that's a copy.
Meaning like, there's this fantasy that I would close my eyes, I would feel like I'm going through a tunnel and suddenly I'm in a computer. That's the fantasy, yeah, But in reality it's like I'll close my eyes and I'll open them again, and then now suddenly there's something that's like me on the computer.
Yes, I think so.
But for the thing in the computer, they would have the experience of going through the tunnel over to.
They Well, they wouldn't exist before, so maybe they would have a memory, you know, like a false memory of that.
Oh, false memory. This gets so tricky. This episode reminded Casey of a short story called The Copy by Paul Jennings, where a kid has a machine that can copy things, except the copies come out mirrored. He eventually clones himself. Then the two clones fight and he kills the clone. But then later his mom tells him he's writing with his left hand instead of his right hand, and that his hair is parted in the other direction. In other words,
he was the clone and he didn't know it. That is creepy indeed, So if you want to learn more about how scientists think about the idea of uploading your brain, go check out that episode. The next person I asked was our editor Rose Segura. Rose lives in Spain and she puts the whole show together, adding music and sound effects. She's basically the reason we all sound so smart. I asked her what her favorite episode was, and she said there were many, but the episode about taking an elevator
to space was a particular favorite. I guess for her a rows above the others. Today we are going to space. No, we're not going to strap ourselves to a giant rocket full of flammable fuel. Instead, we are going to take the elevator. It may seem like science fiction, but a space elevator is something serious scientists actually think is possible to build.
If you're not using a space elevator, the alternative is a rocket, and rockets are dangerous and rather explosive. And so the idea of a space elevator is if you put like a really big spool of cable right at that altitude and just sort of let it down very gradually and slowly, and.
Then you have this straight or mostly straight cable that goes from the surface of the Earth, so it's a big stationary cable. And on this cable you would put a climber or an elevator car or something which lifts your payload up to whatever altitude you want.
Rosette said this was a favorite episod it because when editing the episode, she felt like she was traveling around space without a spaceship or spacesuit, just pushing a button while of course listening to elevator music. Rose said she liked how in the episode we make several stops kilometers away from the surface of the Earth to learn about the physics of space, which made her feel small lying in orbit around the planet.
We want to advance the development of the space elevator and hopefully get it built within our lifetimes. So that's a perfect place to build solar power satellites. Rather large habitats could be built there, Okay, colonies, things like that, orbible factories. If you want to go to Mars, then you can get to Mars in about sixty one days.
Oh, it's doable.
Yeah, I mean the question is do you have an economic case for doing so? Right, That's that's a real question.
Now for me, I have three favorite moments from the years. Was when I got to visit a quantum computer lab at Caltech for the episode What Is a Quantum Computer? The lab is led by Amazon's head of quantum hardware and my friend, professor Oscar Painter. Hey, Oscar, how are you.
Good to see you after so many years?
Yeah, it's been a while. Huh.
Yeah.
All of these control electronics, right, is to use to control about twenty of these quantum bits.
There's twenty quantum particles correct.
Which we are manipulating as quantum bits, and that circuit lives down inside of this special refrigerator. And this refrigerator is under vacuum, the temperature which is about ten million degrees above absolute zero.
Ten million degrees so.
To give you an idea the coldest darkest parts of outer space or that universe. Yeah, but this thing's about thirty times colder than that.
Even whoa. It's just cool to be there and to be able to take listeners with me, to experience what it's like to be in front of such a cutting edge technology. Now. My second favorite moment was when I got my kids to do a live taste test of different meats for the episode Why does frog Taste Like Chicken? Okay, I'm gonna give you four meats and you're just gonna tell me what do you think of it? Oh? Very well, taste like chicken. Does not taste like chicken.
Chicken?
Probably the rabbit or the alligator alligator meat. Yeah, okay, it's just a lot better. Very chicken, very chickeny chicken chicken like.
This is probably the frog meat.
What do you think? It is?
Very lushy?
No, how about the taste ye quin, So the alligator meet definitely like chicken taste like overcooked. Okay, what do you think of your dad experience unsuing? First of all, I was surprised my teenage kids agreed to do it, And second of all, we actually learned a lot. We kind of set the stage for that episode really well. Plus I like that in that episode we learned that lots of meat taste like chicken because basically all meat is made of the same molecular mechanism and proteins. What
makes different meats taste different is something else. So if you want to know what that is, go check out that episode. And my third favorite moment from the year was when I interviewed Professor Jim Anderson for the episode Do Animals Understand Death? In the episode, doctor Anderson tells the story of a chimpanzee named Pansy who passed away of old age, surrounded by her and best friend who comforted her in her last hours.
The old female chimpanzee, she was lying up on a platform. All three of the chimpanzees in the group came over and gathered around her at once, and this was the.
First time this was happening.
And two of them were grooming her, her daughter, and her long term friend, another adult female, and then the adult male in the group came over and he bent down and looked closely into her face, and then he took her by the shoulder and gradually shoot her shoulder while staring at close range into her face. And then he laid her shoulder back down on the ground, looked
at her, and then moved away. What we had witnessed was the Chris moment, where the adult male seemed to be checking for any signs of life and perhaps realizing that she had gone. Her daughter slept beside her all night long.
Wow.
And then the following morning, her long term friend came over and sat by her. And because of that response is by the male, he had left some straw on her, so she gently cleaned the straw of her OIDI and her sheesh and just sat by her for a while.
Wow.
Now I did this interview while I was traveling. I was in a hotel room in San Diego and doctor Anderson was in Japan, and it was just a very profound moment hearing a scientist talk about how animals relate to dying and how he knew the end of his career, things about his life. If we haven't listened to that episode, I highly recommend it. Okay, with that, we reached the end of the episode and twenty twenty five. We look
forward to making more episodes for you next year. We're gonna start twenty twenty six with episodes about the signs of imagination, whether supersensus exist, and why we procrastinate. At least I think we'll get to it. We'll see anyways, Thanks again for listening to sign Stuff. See you next
time you've been listening to science Stuff. The production of iHeartRadio, written and produced by me or Yham, edited by Rose Seguda, executive producer Jerry Rowland, and audio engineer and mixer Kasey Pegrom. And you can follow me on social media. Just search for PhD Comics and the name of your favorite platform.
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