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Modern physics is forcing us to rethink existence | Michelle Thaller: Full Interview — Transcript

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0:00My name is Michelle Thaller and I am an
0:02astronomer. I work at NASA's Goddard Space Flight Center.
0:06How astronomers seek to answer the biggest questions in the universe.
0:11There's sort of two words that float about. There's astronomer and astrophysicist. And
0:14you know, it kind of depends on whether you're trying to put on a more friendly or formal vibe.
0:17I think they really these days mean the same thing. I think there was a time when there was
0:22sort of a separation of duties. There were people that say a hundred years ago would would map the
0:27stars and create all these wonderful catalogues of stars and you might call those astronomers.
0:32You know that the name is from astronomy, to name the stars. And then there were people that
0:38tried to figure out what the stars were and how they worked, what the science of it was,
0:42you know, behind all that. Those would be the astrophysicists. And these days, the two studies
0:47are really the same. If you're an astronomer or an astrophysicist, you pretty much do the same
0:51thing these days. The word that was probably the best word, astrology, to study the stars,
0:56that one was already taken. A lot of the questions that I get from members of the public are these
1:01vast conjectural questions like, you know, is there a multiverse here? What happened before
1:05the big bang? So, for my doctorate, you know, for my research, um, I studied binary stars, you know,
1:11I I studied two stars that orbit each other. And most stars in the universe are like that,
1:15by the way. And uh in the case of my stars, they had these wonderful colliding winds of high energy
1:21particles that produced these giant shocks in the sky. The fun thing is that for for a while
1:26at least and maybe today, uh there are some stars in the sky that I've probably spent more time
1:31with than anybody else in the world. You know, I observed them for hours and hours trying to figure
1:36out how these uh colliding atmospheres worked. In the case of myself, I'm an observational
1:41astronomer. I went to observatories all over the world about 25 years ago when I was most active in
1:46research. I did a lot of research in Australia uh in Arizona, the Kit Peak telescopes, Mount Stromlo
1:52in Arizona. I also used a lot of satellite data. I I had data from X-ray satellites and uh the
1:58Hubble Space Telescope. I actually got some time. You see, as an astronomer, you are allowed to to
2:03write into these observatories. It usually happens once a year. And there is a panel that basically
2:09assesses you know what would all these people around the world like to do with the Hubble Space
2:13Telescope. And the this this panel of astronomers actually decides you know who should get priority.
2:20One of the things about being an astronomer is you end up doing a lot of writing. You end up doing a
2:24lot of writing asking for time on these telescopes and then hoping that your proposal gets selected.
2:30Another thing is you end up asking for a lot of time to write grants for money to support your
2:35work. you know, if you get some time on the Hubble Space Telescope, often it comes with an amount of
2:39money to support the time you're going to do that research. So, it it turns out that being
2:44an astronomer, all of the training is about the math and the physics and you the computer
2:48science and then what you actually do dayto-day is often a lot of writing and a lot of trying to
2:54organize proposals and grants and how you're going to support yourself doing your science.
2:59And then if you work for a large organization like NASA, uh, as some of your time as well is usually
3:04assigned to some specific mission, you know, some specific space telescope where you're going to be
3:09helping clean up the data, figure out how we're going to issue a call for proposals, organize the
3:14panels that are going to vet and look at all these different things. So in a way, you become kind of
3:19an administrator. A lot of meetings. I think that, you know, the normal life cycle of an astronomer
3:24is probably 80% like business person. a lot of meetings, a lot of grants, a lot of budgets. But
3:30then, at least for me, there really was this time. It doesn't happen so much when you're a
3:35more mature astronomer, but when you're really young and out in the field and making your own
3:38discoveries, it really does feel like you're sort of alone with the night sky all by yourself up up
3:43on top of that mountain and you're you're seeing things coming down through your telescope that,
3:48you know, it's a it's a minor advance, but you no human being has has ever seen before. And it's
3:53it's a wonderful feeling of empowerment and sort of, you know, kind of collaborating with the sky
3:58and and seeing what we can figure out. One of the things is when you get a doctorate, you have to
4:04produce some kind of original research, something that's never really been been done before. And
4:09that's not as hard as it sounds. That sounds very intimidating. I mean, how am I going to think of
4:12an idea that nobody's ever thought of before? But nothing in astronomy happens alone. You know what
4:18happens when you're a graduate student after college is you will join a professor doing his
4:23or her research with them sort of as an apprentice and uh and then over time as you get more familiar
4:28with the work they will give you a little piece of that research like hey you go ahead and and take
4:33this part over yourself. You don't really need to think of things entirely you know just off the top
4:37of your head and and come up with brilliant ideas out of nowhere. You start little by little working
4:42with a group of astronomers and then slowly you start to ask your own questions. you know,
4:46maybe they've never had time on a telescope to look up this little bit of it, you know,
4:50or or this little bit of it over here is a new question nobody thought of. And and eventually
4:54you realize that what you're doing is something that hasn't been done before. I guess there were
4:59probably about a dozen stars in the sky, but there were three that I really really focused on. And in
5:04the in every case, these were binary stars. And these were stars that were very massive. Stars
5:10that were say, you know, anywhere between like 15 and 50 times the mass of the sun. big stars.
5:17They actually only orbited around each other every couple of days or at most about a week. So these
5:21are very big stars in very close orbits. And so it should make sense these stars are pouring off you
5:28not only light but but high energy particles, this wind of particles that we call stellar
5:33winds. And then they collide in between these two stars. Sometimes one of their winds will not be as
5:39strong as the other. So the wind from one sort of overtakes the other one and kind of blasts
5:43away the wind from the other one. And as they turn around each other, you actually sort of have this
5:48wonderful kind of three-dimensional view of how that shock wave goes all the way around. And so
5:53I use a technique called tmography, which is the same sort of thing you use in a CAT scan or, you
5:58know, something like an MRI where you're trying to produce a three-dimensional scan of inside
6:02the human body. In this case, the instrument goes around you. But in the case of the stars,
6:07the stars would go around each other. And then I could use this sort of software mainly developed
6:11for medicine to actually try to figure out the structure of these shock waves. This is you know
6:16just sort of work a day astronomy you nothing you know all that incredible or sexy about it but
6:21it helps you understand stars better. It turns out that these shock waves are responsible for
6:27producing a lot of the molecules that we find in space. You know stars create uh you know
6:32atoms. They fuse hydrogen into helium and then eventually helium into larger atoms over time.
6:38But these shock waves, at least in the cooler parts of them, can produce things like water,
6:42the water molecule. And there are, you know, there are some binary stars, like there are some in the
6:47uh the Orion Nebula that are producing enough water in a single day along these shock waves
6:52to fill the oceans of the Earth like 60 times over in a single day. Now, obviously, this isn't liquid
6:58water. This is water in a in a molecular form, a pretty hot gas, actually. But that's where a lot
7:03of the the molecules responsible for life can come from is from these shock waves. So it's a way of
7:08trying to figure out just little by little how the universe really does work, how stars work.
7:13So my research is much more observational, much more about stars. I certainly took classes in
7:20cosmology, the study of the universe as a whole. I took classes in quantum mechanics, you know,
7:25graduate level quantum mechanics, graduate level electromagnetism, all of that. People often start
7:30right off with the, you know, are there parallel universes? And I'd rather they sort of ask me,
7:35you know, what are the importance of binary stars? There's honestly not all that many astronomers by
7:41number that do theoretical cosmology. You know, most of us are trying to figure out things like
7:45how stars are born and how they like live their lives and die. We're trying to figure out what's
7:50left over after a star explodes, a black hole, a neutron star, or we're trying to figure out how
7:55galaxies work, how many galaxies there are, how do we observe them, how do they change over time.
8:00There's only a few of us that are trying to answer questions like, you know, what happened before the
8:05big bang or, you know, are there multiveres? We we all study that to an extent. We all go
8:10to lectures at the conferences. I love going to the ones on, you know, quantum theory and quantum
8:15gravity. Most astronomers study things that are a bit more concrete than that, if very far away. So,
8:23it's often the case that, you know, I'm giving some lecture on this the wonderful new images
8:27of Saturn from one of our spacecraft like Cassini and they're so beautiful and we're learning things
8:32about the atmosphere and look at these pictures of the these little moons we took in the ring system
8:37and we're studying the ring system and we have a wonderful lecture. I turn to the audience and say,
8:40"Hey, any questions?" You know, and somebody raises their hand and the first one is, you know,
8:44are there multiple universes? It's like Saturn. There are some words that are are really easy
8:50to throw around and in science they become interestingly complicated. People often say,
8:56you know, do you believe such and such is true? You know, do do you believe the big
8:59bang is true? You know, do you believe that the idea of multiple universes is true? You know, a
9:03lot of these things. And when you're a scientist, you're aware that what what you're doing is you're
9:10constantly trying to approach reality. you're trying to get closer and closer to describing
9:15something very well, but you you know you're not all the way there yet. And it's quite possible
9:20that we we never will be. It's quite possible that human beings with our our limited senses, our our
9:27limited brains even, you know, won't really know what the true nature of reality is. It's
9:32it's one of these kind of wonderful things that, you know, truth can change. you know, you know,
9:36hundred years ago, people uh were certain that the universe was not expanding, you know, and and of
9:40course we found out that it was. And you have to be able sometimes to take your your very precious
9:46images, you know, models of what the universe is like, about what reality is like, you know,
9:51even about what the definition of truth is. You need to make sure that you're ready to change when
9:55better information comes on board. in physics at least for the last hundred hundred years that that
10:01has really challenged us to leave behind our human ideas of of common sense uh the very definition
10:10and perhaps existence of space and time. The whole idea about what is reality, what is existence, you
10:17know, what am I is a very very complex question now to answer. I mean to give you some ideas
10:25about this there there are some things that are are are very simple like what is the interior of
10:30the sun like? It's obviously something we've never directly observed but we see energy pouring out
10:35of the sun. Uh there are actually uh waves almost like earthquake waves that go around the sun that
10:40help us to study the interior the way those waves travel. But do we know exactly how the core of the
10:46sun works? No. No we don't. There are things that we get pretty close to but we just don't really
10:50have the observational ability to do so. But then there are questions like what are space and time
10:56really? For so long we've just sort of taken it for granted that space and time exist around us.
11:04Time flows in one direction. Space extends perhaps to infinity. But then there was also a time when
11:09we we didn't think that air was anything. People didn't realize that we actually live, you know,
11:14at the bottom of this wonderful ocean of air that is our our atmosphere. People took it for granted
11:18that that air existed. That was actually, you know, proven in the 18th century that this was
11:23actually something. Einstein showed us that space and time absolutely cannot be the simple way we
11:29perceive them. It it all is related around the speed of light. The speed of light is always
11:36constant to any observer. One of the myths about Einstein was that he pulled all of these amazing
11:41ideas just kind of, you know, out of his head from nowhere that he wasn't part of the scientific
11:45establishment. Well, in fact, he was. Uh he was a professor. uh he was actually a graduate student
11:51trying to get a job when he was working at that patent office that he had that miracle year where
11:55he came up with the the theories of special and general relativity among other things. So here's
11:59an example about allowing yourself to define whether something is true in kind of a bit more of
12:05an active way. Isaac Newton was able to describe very very well how gravity worked. He was really
12:12one of the first people that said there's this force of gravity and he just said that it's a
12:16force. this force permeates the universe and this is why the planets orbit the sun you know this is
12:21why apples fall from trees is they're reacting to this force and by using his equation of gravity
12:27you could calculate that force very very well so you had this you know great thing the force of
12:33gravity the force exists it binds the universe together but then you have to ask the question
12:38okay what what do we mean by that what is the force of gravity what is it really what what
12:42what causes it and it took Albert Einstein to say that that what we think of as gravity is actually
12:49a curvature of space and time. Things have to follow space and time. We are all embedded in the
12:54space and time of the universe. So if that space and time has a shape to it, a curve to it, we
13:01have to follow that. Light has to follow that. You know, light itself that has no mass can actually
13:07bend and go into a black hole. And that's because the light has to travel through space and time and
13:11the space and time itself is bent. So all of a sudden there was this answer. What is the force
13:18of gravity? It's a bending of space and time. So is that it? Is that the end of those questions
13:23that we can ask there? Well, how about the rather obvious next one. What is space and time? Okay,
13:29there's this thing that Einstein called spacetime that that you know space and time are sort of
13:33mixed together. They're they're two sides of the same coin. When you change one, the other has to
13:37change. If you are in a gravitational field and and space is bent, time actually slows down. It
13:43actually affects time as well. We know that these two things are bound together. But what are they?
13:49Time can be different for different observers depending on your velocity. If you're going very
13:53close to the speed of light, as people observe you going by, they see your time is very slowed down.
13:58If you're actually a photon going at the speed of light, time stops entirely. So what do we mean by
14:03this thing called time? And this is now what some of the major physicists of the world are grappling
14:08with. And they are trying to come up with some very interesting answers. I think answers that
14:12will be very challenging for us. Imagine being a physicist back in the early 1900s and having
14:18this this young Albert Einstein tell you space and time are bendable. You can change them. You
14:24can manipulate them. You might have thought they were crazy. How about looking at space and time
14:29instead as a consequence of quantum mechanics? A lot of people have been saying that relativity and
14:36quantum mechanics don't match. They don't work together. And this is true. This has been true
14:40since the beginning of relativity and quantum mechanics at about the same time. Relativity
14:45says that if you have a certain amount of mass, you can actually say space bends this much. And
14:50quantum mechanics says that everything is down to probabilities. The universe never has set answers,
14:56but maybe the probabilities of a particle being here versus there. Even the curvature of gravity
15:02must somehow be probabilistic. And Einstein didn't like that. there was no way to work that into his
15:06equations that actually, you know, made them both work at the same time. What if we were asking the
15:11wrong question? What if we're not looking at two different things? What if we could actually say
15:17that spaceime itself is a consequence of quantum mechanics, not something separate from it, not two
15:22things that are clashing together? And this is the idea now that perhaps quantum entanglement,
15:29if you look at it correctly, is spaceime. Now quantum entanglement isn't just a term
15:35you can throw off very very easily but this is something that we have now observed and been able
15:40to replicate in laboratories all across the world even in space actually. If two objects interact
15:47together they can actually sort of become in a sense the same system under the laws of quantum
15:51mechanics. So let me just give you a very simple example of this. A lot of people know the model of
15:56an atom where you have this uh nucleus of protons and neutrons and the electrons can be in different
16:02orbits around there. In fact, in in a single orbit around the nucleus, there can be two electrons,
16:09but those electrons can't be exactly the same. You can't have two that are identical. They have
16:13to have opposing spins, angular momentum. It turns out you can have two electrons in each
16:18one of these orbits, but the electrons can't be identical. They have to be spinning in opposite
16:23directions. It's a strange idea that electrons spin, but at least you can say that there's
16:28some kind of intrinsic angular momentum. What we think of as something spinning, that's actually
16:33a property that a particle can have, whether or not there's actually like a physical little ball.
16:37Electrons are not little balls, but they do have a property of spin of uh angular momentum. You could
16:43have two of them in the same orbit as long as they have opposing spins. One spinning one way, the
16:46other one's spinning the other way. So, say that one is spinning, you know, up and one is spinning
16:50down. the way my thumbs are pointing, you know that these two electrons have to have different
16:56spins. So, what happens if you actually take them out of that system? You take them away from
16:59the atom entirely and now you've got these two little electrons somewhere in space and then you
17:03know that they have to have opposing spins because they once were in that same orbit. Well, okay. So,
17:09now separate them. Separate them by a couple of feet, maybe a couple of miles. How about a couple
17:14hundreds of miles? Maybe there's no limit. We found out that if you use some sort of energy
17:21to change the spin of one of these electrons, the other one basically instantly knows that that's
17:26happened. And it's not that there is a signal passing between one of these to another because it
17:32doesn't travel even at the speed of light. It is an instantaneous flip. It's not a signal traveling
17:37because these two things are basically the same quantum system. In the rules of quantum mechanics,
17:42they are the same object. So there's no signal really to travel to a quantum system. There
17:48really isn't any such thing as space or time. It will adjust instantaneously because it's the same
17:54system whether it's microscopic or whether it's many thousands of miles apart. They're the same
18:00thing. Could it be that everything is entangled to everything else in some way? Well, I mean,
18:07there once was a time when the universe was very small. You know, the time right after the big
18:11bang where in a way we were all kind of the same particle. That particle has changed and expanded.
18:17But is it possible to think that in some way we're actually the same quantum system to everything in
18:21the universe. And what we perceive of as space and time is the degree to which we're entangled.
18:29We're entangled more to things that are closer to us that have a chance to interact with us. The air
18:33in this room, the space that's only outside in my yard. I'm less entangled to things that I've
18:39not been able to interact with much for a long time. Things like distant galaxies, I haven't been
18:43close to them since the beginning of the universe. Einstein asked, "What is gravity really?" And now
18:50we have to ask, what is spaceime really? And we know it can't be as simple as the way we perceive
18:57it. Maybe the underlying quantum reality of the universe is that everything in a way really is
19:03still the same quantum system. I've always thought when people think about alien civilizations
19:09and they say the flying saucers and UFOs and spaceships, I kind of wonder if the next step
19:14in really understanding reality is that there's no such thing as distance. And maybe a very advanced
19:20civilization that can somehow manipulate that. You don't have to travel anywhere in a spaceship. You
19:26simply figure out how you access this entanglement of the rest of the universe. Could it be that you
19:32are really the same quantum system as everything in the universe at once? And that degree of
19:37entanglement is what we think of as space, as time, as gravity. That's an amazing idea and
19:46it's one that more and more people are starting to look at. Do we know this is true yet? No. This
19:50is still conjectural. But the physics is working very well. And one of the promising things is that
19:56the equations of gravity emerge now from quantum mechanics. They're no longer general relativity,
20:03quantum mechanics, they don't mix. You start with quantum mechanics and gravity emerges from it,
20:08from the degree of entanglement. So stay put for a couple more decades. And uh like I said,
20:14maybe someday we're actually going to figure out what the underlying structure of this entanglement
20:18is and then we can actually move outside of space and time. When you are pure energy,
20:25you have to travel at the speed of light. A photon has to travel at the speed of light. It
20:29can't go any other speed. A photon can't exist in a state where it's only moving at say 20 m hour.
20:35It has to travel at the speed of light. And when you're traveling at the speed of light, you don't
20:40experience space or time. You're probably familiar with Einstein's idea that as you go faster and
20:45faster, closer to the speed of light, time slows down for you compared to an observer watching you.
20:51If I'm sitting here still on the Earth and I watch somebody in a spaceship whizzing by at half the
20:55speed of light, I see them very very slowed down compared to me. And when you're actually going at
21:01the speed of light itself, time stops. That means that light does not experience space or time in
21:08any kind of extended way. All points in space are one and all time. All points in time are one. Time
21:15and space don't exist to a photon the way it does to us. And yet I am made of something that you
21:21can convert to photons and back and forth. And I experience space and time. I experience those as
21:27extended properties. There's a duality to the universe. And I think this is going to become
21:31one of the most important things for modern physics that the next revolutions in physics.
21:37Light around us. I mean, it's coming from the sun through my windows. It's coming at me through,
21:40you know, the lights that we have in the studio doesn't experience the same universe I do. to it
21:45in a real way. The universe never expanded. All points of time and space are still one from the
21:52perspective of a photon. And I am made of photons kind of. But why do I experience space and time?
22:00Space and time as we perceive them cannot be the end story. There has to be a different perspective
22:08that shows us a reality that that our human brains don't perceive yet. But the physics all around us
22:14of something something as simple as light demands it. The things that kind of give me chills is just
22:20how little we understand the nature of reality itself. If something bouncing off me right now
22:25doesn't experience the universe as having even expanded, what does that mean? So that equation
22:31equals mc^2. I mean it's it's useful. You can use it to power nuclear reactions. You can use
22:36it for particle accelerators. But it actually sort of claws away the fabric of reality itself
22:41and challenges us to ask what's underneath. To me, I think one of the the most amazing things
22:47about the universe is the question what is energy? And this can go very very deep. Uh you know a lot
22:54of us are familiar with you know energy is it takes energy to accelerate something like you
22:59know to actually like throw a softball that takes you know energy chemical energy from your arms or
23:03you could say something has potential energy like it's sitting at the top of a hill and it's prone
23:07to roll down the hill in the gravity field of the earth that's actually called potential energy. But
23:12then there's also the energy that's just intrinsic in matter. One of the things that always gets me
23:17about this is that energy, light, you know, light is sort of a form of pure energy and us, you know,
23:24matter, we're made of particles like protons and neutrons and electrons. They seem so different.
23:30They seem to have completely different views of the universe as well, which I think is one of
23:34the more interesting and disturbing things I know about in modern physics. Let's just think about
23:39the idea that energy and mass really are somehow the same thing. that mass is some like coagulated
23:46stored form of energy. That means the two of them you can actually go from energy to mass and and
23:52back and forth. And that's the famous equation that Einstein came up with equals mc^2 that in
23:57any amount of mass there is an equivalent amount of energy and the two are basically the same
24:02things. The universe actually doesn't seem to see much difference between mass and energy. As long
24:07as the amount is the same, it can exist in either form. And let me give you some examples of that.
24:11The way a nuclear reaction works like a nuclear fusion reaction is you convert some amount of mass
24:17into pure energy. Nuclear fusion actually brings particles together, slams them into larger atoms
24:23and in the process energy is released. So a little bit of mass is lost but energy is produced. It
24:30also goes the other way. In a particle accelerator you get more and more energy because of collisions
24:35of particles colliding together. They produce so much energy that as long as as a given particle
24:41has that amount of energy, any particle can pop out of that reactor. And that's how we find new
24:46particles. As we get to higher and higher energies in a particle accelerator, just having that amount
24:51of energy around the universe can manifest it now as mass takes a lot of energy equals
24:57mc^ squ. Energy equals mass time the speed of light squared. That's a lot. But energy and
25:03mass pretty much are the same thing. One of the ways the universe seems to do this is something
25:08called virtual particles that if you have um you know just just the energy you know around you the
25:15energy of space and time itself there sort of an inherent energy just in the universe that
25:20energy can actually become mass it'll actually form what we call virtual particle pairs like
25:27an electron and its antimatter equivalent a posetron. those two particles will just
25:32literally pop out of the universe because there's that amount of energy around and then pretty much
25:36always they just annihilate each other. They just go back. Matter and antimatter annihilate
25:40back into pure energy. And this is happening all around you. Everywhere around you in space,
25:46these little virtual particles are forming and collapsing together all the time. Some of the
25:51more interesting things happen in the universe when those particles get separated. Uh one example
25:55is around a neutron star. It can actually make a beam of energy coming off the magnetic poles
26:00of the neutron stars by having virtual particles be created and then accelerated by the magnetic
26:05field. So all of a sudden you have this energy that wasn't there before produced by the virtual
26:09particles themselves. As you get to higher energies, you know, say you have a very very
26:14strong magnetic field, very high energy. Again, we find these around neutron stars. That can start
26:19creating lots and lots of these virtual particle pairs. And the more energy you have, the more of
26:23these little virtual particles you get until space itself takes on an aspect of having mass. The
26:29density of these virtual particles right around a neutron star, even in empty space itself, would be
26:34about three times the density of iron. It's just just unbelievable. So energy and mass really are
26:41the same thing. They're two sides of the same coin. They can be converted back and forth to
26:44each other, and the universe doesn't really care. It sees them both the same way. When people think
26:49about the most dramatic things in space, they they tend to go immediately to black holes, which are,
26:52you know, absolutely incredible. You know, out of control gravity that you can actually, you know,
26:57suck light back in. It's just amazing. But I think neutron stars deserve a little more love because a
27:02neutron star is also created when a massive star dies, but it doesn't have quite enough mass to
27:08actually collapse into a black hole. It actually leaves behind a thing, you know, a physical thing
27:13that you can study. So while black holes are just sort of this bottomless pit, you know,
27:18with neutron stars, you have this very strange thing that you can look at them, you can observe
27:23them, you can take real measurements of, and you're looking at something that is mind-blowing,
27:28and in some ways our physics really isn't ready to describe yet. The thing about a neutron star,
27:33you know, why why do we call it a neutron star? For one thing, and I'm I'm going to
27:36really oversimplify here, but basically when you think about an atom, you have protons and neutrons
27:42in the nucleus of the atom, and then electrons are in in orbitals around farther away from around the
27:47nucleus. Amazingly, the gravity of a neutron star is so strong that it actually collapses
27:53the electrons into the nucleus. The gravity crushes electrons into the nucleus. And if
27:59you crush an electron and a proton together, one is negatively charged, one is positively charged,
28:04you will get a neutron. A neutron actually will naturally decay sometimes into an electron and you
28:09know a proton. You have an object that's mainly made of neutrons. There are some protons as well.
28:15And it basically has the density of an atomic nucleus, but it's about 10 miles across. I mean,
28:21that's like one big nucleus. 10 miles across. It's incredible. And because there was so much collapse
28:29involved in their forming, you know, when when you think about what they call the conservation
28:33of angular momentum, if something is spinning and stars actually do spin, if you collapse that down,
28:40you actually spin up much faster. It's the classic ice skater analogy. You have an ice skater with
28:45her arms out spinning around and then as she draws them in, you can watch that ice skater spin faster
28:49and faster. Same thing happens. But in this case, you actually have a ball that is about, you know,
28:5510 miles across spinning 500 times a second. I mean, I mean, that in itself is just mind-blowing
29:01to think of, right? Something that big spinning that fast. Now, recently, neutron stars had
29:08played this important role in explaining something that we had no explanation for. They were very,
29:13very mysterious. In fact, there were some people that were wondering if we were actually looking
29:18at might be a signal from an advanced alien civilization. Those are called uh fast radio
29:22bursts. Now, uh fast radio bursts have been in the news for a couple of years because there
29:28was so much energy in these mysterious bursts of radio emission that we couldn't explain what was
29:33going on. So for example, we would have uh you know our radio telescopes would register a burst
29:39of emission and the uh that burst would last say a millisecond 1,000th of a second. That's about how
29:46long these things would last. But in that 1,000th of a second enough energy was radiated similar to
29:54what the sun puts out in a week in a millisecond. And so we were getting these signals from you know
30:00all over the sky. We were trying to figure out what that could possibly be. How could you make
30:05that much of a tight burst of radiation in that small amount of time at those incredibly high
30:10energies? So, the race was on to try to figure out what these fast radio bursts really were. Luckily,
30:16we have many, many things that are at our disposal to try to study these things. Right now, we have
30:21many high energy telescopes that actually are orbiting the Earth that measure things like X-rays
30:25and gamma rays, the most uh energetic types of light. light you only get if something is in the
30:31millions or billions of degrees. It'll actually emit X-rays and gamma rays. A wonderful thing
30:36is that we actually started to be able to kind of pinpoint to where these things were coming from in
30:40the sky. And as we did that, they actually seem to line up with neutron stars. So neutron stars
30:47are most likely responsible for these fast radio bursts. Now, exactly what's happening is something
30:53that we don't really know yet, but it probably has something to do with almost like an earthquake.
30:58an earthquake, you know, you you have something, you know, our something in our crust shifts and
31:02there all these waves that go through the earth. It's actually the way that we know the interior
31:06of the earth is by studying those waves. You know, we've never been able to actually take a sample of
31:10the fact that the earth has magma all the way down until you get to a at first a liquid metal core,
31:16then a solid metal core. No one's ever seen that physically, but we actually watch how
31:21these waves of compression go through the earth and we can put together what the interior of the
31:25earth must be like. The same thing may be possible for neutron stars, but on a much
31:30more energetic scale. You have this this this ball of of neutrons. Incredible densities,
31:36incredible temperatures. And we think that there must be a crust of neutrons actually that actually
31:41forms on the outside of these stars. And inside is probably a fluid, a fluid of pure neutrons.
31:49We know this because neutron stars as they spin sometimes seem to sort of slosh around almost like
31:54a water balloon. So, we've modeled that to be sort of a crystallin thin crust. I can't imagine what
32:00that would be like. I mean, for one thing, that the gravity would be so intense near that crust
32:04that it would just crush you into just particles basically on the surface of that neutron star.
32:09But if that crust were to have a flaw in it and there was some sort of uh you know a quake, it
32:15shifted somehow, it would send compression waves through the neutron star and release tremendous
32:22amounts of energy in a quick little moment of the crust actually sort of refiguring itself. So right
32:28now our best explanation is that these amazingly mysterious fast radio bursts are probably neutron
32:34star quakes. And just like earthquakes have taught us so much about the interior of the earth,
32:39now we're looking at the signal, you know, even in a thousandth of a second, take that signal,
32:44pull it apart, and try to find the structure that's going on inside that burst of radiation
32:49and see if we can reconstruct what the inside of a neutron star is like. Neutron stars really are
32:54these real monsters. Unlike black holes, you can see them. You can see their surfaces. You
33:00can actually map how the radiation is coming off them. When it comes to really mysterious parts of
33:05the universe, but things that you actually can measure, I'd say go for some neutron stars. The
33:10closest neutron stars to us are very far away. You know, they're on the order of many hundreds
33:15or thousands of light years. So, luckily, they don't really cause any uh trouble for us. But the
33:19question I've always wondered is how close could you actually get to one of these things and and
33:23make a measurement before you would just be fried by radiation? Or in in the case of a neutron star,
33:29something stranger still. A lot of people are familiar with Einstein's famous equation E= MC^2
33:35which says that energy is equal to mass times the speed of light squared. And what that really means
33:40is that in any amount of of mass, so if I think about like the mass of my little finger, there's a
33:45tremendous amount of energy. So if I could convert my little finger into pure energy, the nuclear
33:50bombs that were dropped on Japan, you know, converted on the order of like a dime's worth of
33:54mass. So, you know, there would be many, many, you know, nuclear warheads right in my little fingers
33:59worth of energy. But E= MC^² also goes the other way. If you have a lot of energy, that basically
34:06starts acting the same way as mass. And it does so in something called virtual particles. If you have
34:13a a lot of energy in a small space, the universe will start to actually create particles that have
34:18the same energy in their mass. So a lot of energy can actually become mass. And and this is how our
34:25particle accelerators work. This is why you can discover new particles because if you just have
34:30a very energetic collision, like you take two gold nuclei and you slam them together, there's
34:36so much energy produced in that collision that it starts to pop off particles just from the amount
34:41of energy. And as long as you have enough energy, you can make any particle the universe has. The
34:46particles come off in all different flavors as long as they have the same amount of energy that
34:50that collision is putting out. So neutron stars are doing something kind of like that. They're
34:54actually becoming sort of natural particle accelerators in a way just because of their
34:59mass. There is so much gravitational contraction that the magnetic field, the electric field and
35:05magnetic field of that star is actually compressed around this tiny little object. Now, so neutron
35:11stars have magnetic fields that are trillions of times more strong than a typical magnet you might
35:16have in your home, like a refrigerator magnet. It would actually pull regular matter apart,
35:20just the magnetic field. But there's so much energy in those magnetic fields. So so think about
35:25E= MC². There's so much magnetic energy right around a neutron star that the vacuum of space
35:31itself starts to make these virtual particles. And I was at a lecture one time and this just blew my
35:37mind. You know this is what happens when you work at NASA and you know you go into a lecture your
35:41colleagues are having you just you know any any day of the week. And they were saying that right
35:45around a neutron star the density of space itself the vacuum of space right a place where it's a
35:51vacuum. there aren't any particles otherwise has about three times the density of pure iron
35:57just from that amount of virtual particles being produced by the energy of that magnetic field.
36:02So what's it like to fly around something where space itself has the density of three times of
36:07iron? What's that like? What does that look like? I would love to see what a neutron star looks like
36:15from a safe distance. And I'm not exactly sure what that is. When you're dealing with so much
36:20energy that even empty space becomes much more dense than iron. And once again, these are real.
36:27They're up in the night sky tonight. I mean, you can't see them because they're they're dim and
36:30they're small and they're far away. So, it's not something we actually see in the night sky. But
36:34all around us, we're getting the radiation, the high energy radiation from these things that are
36:39are real monsters. Our sun has this wind of high energy particles. This is something that was only
36:48relatively recently discovered. I mean, when you think about the fact that the very first
36:52satellites we put into space, you know, starting in, you know, the very late 1950s, you know,
36:57and 1960s, they they realized that there was this source of of of radiation up there. There was,
37:02you know, a lot of particles around up in space. I actually had the honor of being next to this
37:07man named Eugene Parker. We have a a a wonderful mission named after him called the Parker Solar
37:13Probe. This mission is actually orbiting around the sun right now, closer than any human-made
37:18thing has ever orbited the sun before. It's really really exciting. He was I I believe 94 years old
37:23at the time of the launch. Usually we we only name spacecraft after people postumously after they've
37:30died. He was the one that basically predicted the solar wind and was the the one that figured out
37:34how it worked. And of course, we're still figuring out a lot of the details, but they just couldn't
37:38think of anybody better to name it after than him. And so that was lovely. The source of these
37:43these these high energy particles and exactly how they get accelerated away from the sun is is what
37:48we're studying right now. We know that this wind of particles, when I say high energy particles,
37:53I'm talking electrons and protons and, you know, sometimes, you know, as large as like the nucleus
37:58of a helium atom, something like that. and they uh they get blasted through our solar system at
38:03a million miles an hour in some cases. And so, you know, we have this very high energy wind.
38:09It changes planets. You know, it's responsible for Mars losing its atmosphere over time and becoming
38:15this kind of cold dead desert. It's responsible for for Venus becoming sort of this this hellish
38:21thing that we know it. It actually blasted away all of the lighter molecules like water.
38:25It left Venus with an atmosphere of carbon dioxide and sulfuric acid. And even Pluto,
38:30you know, all the way out at the edge of our planetary system, Pluto is is still losing tons
38:36of atmosphere a day, blasted away by this wind of high energy particles. The only reason the Earth
38:41is not really affected by it much is because we have a very strong magnetic field. And so,
38:47you know, our molten metal core, all that molten metal moving around inside the Earth generates
38:52kind of a magnetic bottle around the Earth. And that protects us from this solar wind. But someday
38:57the sun will actually, you know, pretty much blast away our atmosphere anyway. So, you know,
39:02planets change and and one of the important things about knowing about this wind is we have
39:07to understand our environment in space. The solar wind normally is at levels that humans can take
39:12quite quite easily. You I know that some people that are into conspiracy theories say, you know,
39:16how could we have gone to the moon because there's so much radiation in space. Well, the answer is we
39:21we kind of got lucky with Apollo because a normal day, the solar wind is a a radiation level humans
39:27can handle quite easily, you know, up in space or, you know, on the moon. Problem is that if you
39:32have a solar storm, a very very violent event that unleashes lots of this solar wind, a lot of times
39:39we call these coronal mass ejections. The corona is the outer layer of the sun's atmosphere and and
39:44coronal mass ejection. All this stuff comes out at once. It's true that if if a big one of those
39:50happens in the direction where astronauts are unprotected from the Earth's magnetic field, they
39:54could die. I mean, it could actually give them a fatal dose of of radiation. That is something
39:59that we need to consider. And it turns out that we got kind of lucky that, you know, in between some
40:04of the Apollo missions when no astronauts were up on the moon, luckily we actually had events,
40:09solar events that would have endangered the astronauts. That's why it's hard to go to the
40:14moon and also to Mars is to protect people from that that radiation. It's not that hard to protect
40:19you from it. I mean, a good amount of water could do it. Like if you had a water tank in your
40:24spacecraft and you could shelter behind that. It's just that you'd have to bring up a decent amount
40:28of water and that's a lot of mass. Or in the case of the moon, I think if if you could dig down just
40:33about 10 ft below the lunar surface, that amount of rock above you would shelter you. But then we
40:38need to bring, you know, construction equipment to the moon that can dig a tunnel, right? So I mean I
40:42mean there's all kinds of things we're considering as to how you would handle that. So what happens
40:45with shock waves is that you have say two binary stars close to each other and they both have a
40:51wind of particles. You in this case we don't say a solar wind, we say a stellar wind because we're
40:56talking about stars. But it's really the same thing. The main difference is that the stars
41:00that I was studying are very massive stars. Stars that have, you know, anywhere from, you know,
41:05let's say 20 to 50 times the mass of the sun. And they actually have really strong winds. much
41:11stronger even than the sun does. So when you have these two stars close to each other, these winds
41:16come off and they collide. And when that happens, I mean I mean literally the the the electric and
41:22magnetic fields, you know, sort of entangle with each other. The particles collide together and
41:27that creates a very very hot area that we call a shock wave. As all of this stuff comes together,
41:32basically slows itself down as it collides, you get all of this heat and radiation emitted along
41:38that that that shock front. Those are wonderful shock waves that are created by colliding winds.
41:43Yeah. So, one of the big challenges right now, especially as we consider putting astronauts back
41:48on the moon, is there a way to predict when one of these violent events is coming? The answer is
41:54uh yes, in several ways. So in the in the very simplest way, we actually have spacecraft as I
42:01mentioned there's a spacecraft orbiting the sun right now. There's actually two, the Parker Solar
42:05Probe and the Solar Orbiter from the Europeans. And we also have other spacecraft between the
42:10Earth and the Sun. As one of these, you know, big belches of material, charged high energy particles
42:16comes out of the sun, it will hit different satellites that will measure how fast it's going,
42:21how much energy is being delivered. And usually in the case of of say the moon, uh the the earth
42:26has about a day or maybe two days notice. So you could say to the astronauts, hey, something's
42:30coming. You know, everybody go shelter. You know, as long as you had a good shelter there. But then
42:34there's the question of can you predict it before it actually happens. And this of course is one of
42:40the the huge goals all over the world of people called helopysicists. Helio for sun and then
42:46physicists. So people who are are physicists that specifically study the sun. the the sun is this
42:51incredible magnetic marvel. A magnetic field is generated by moving charges, right? So you think
42:58about like the the charges in moving metal that generates a magnetic field in an engine. In the
43:03case of the sun, the sun is made almost entirely of hydrogen, but it is so hot on the surface that
43:09that gas has become ionized. that what that means is there's so much energy that electrons that
43:15normally orbit around a nucleus, the electron gets so much energy it just takes off and that leaves
43:21two particles that are charged, an electron and a proton. Anything that has an electric charge,
43:26a magnetic field can bend. And so when you see these wonderful like loops on the sun and and and
43:32you know all of these beautiful shapes, that's the very hot electrically charged gas just following
43:37the magnetic field of the sun. The name for it, and it's kind of a confusing name, is plasma. You
43:43know, you can actually see the shape of the sun's magnetic field, but it's chaotic. It's incredibly
43:49complicated. So, you have these wonderful loops of magnetic energy, you know, all this stuff
43:54following it. So, how do you predict, you know, when one of those loops is going to break open and
43:58and actually like spew stuff out and create one of these big ejections? We're getting better at it,
44:04but it's still something that we don't understand. I mean mean something that simple of you know our
44:10own star when is there going to be a really big storm we can't predict it down to the hour we can
44:15say there's a very active region here that looks like it might produce something but there's no
44:19way to guarantee that actually it kind of reminds me of the year uh 2012 because I was having sort
44:26of a difficult year that year because uh people had this idea of the Mayan apocalypse. It was
44:302012 apparently that was the end of some calendar cycle in the the Mayan calendar.
44:36The the idea was that something catastrophic was going to happen. And I would get calls, seriously,
44:41people would call us at NASA and say, you know, I don't want my pets to suffer. You know,
44:45should I euthanize? I I actually got a call somebody wondering if they should euthanize their
44:49pets. Other people would say things like, is the world going to end next month? And and I' I'd say,
44:54you know, look, okay, if I knew the world was going to end next month, do you think I'd be here
44:58in my office answering phone calls? I don't think so. And we kept telling people that there was
45:02really no reason to worry about anything. There was nothing unusual astronomically happening. The
45:08sun was in a naturally active period that year. Every 11 years or so, the sun becomes very active
45:15and then it kind of gets quieter again. One of the reasons I know this is cuz I I love to see the
45:19northern lights, the auroras, you know, those are caused when you get these charged particles in our
45:24atmosphere and uh they create these beautiful glows around the poles. You know, for us,
45:28that's really the only thing we really notice for the most part. What happened actually is
45:31that there was a colossal coronal mass ejection, one that would have actually been dangerous to our
45:38power grids here on Earth. It wouldn't have caused any damage to like people or animals or plants,
45:43but it would have actually dumped electric current into our magnetic field and it it
45:48probably would have taken down, you know, a lot of power grids. It would have caused a lot of damage.
45:53The thing though is it went off on the other side of the sun from the earth and we had satellites
45:59out there in that other direction out in the solar system and and and they got knocked silly by this
46:04big burst of charged particles from the sun. And so we looked at that and we were able to observe
46:09it and see what had happened and track it and all of that. We all kind of went the the sun spins.
46:16It actually doesn't all spin at the same rate. The equator spins faster than the poles. It's
46:20not a solid thing. It kind of twists itself up. the sun, you know, on average spins about once
46:24every 29 days. And so we don't really know. There could be an active region that's about to blast,
46:30but then it could spin out of our view and and so we're safe from it. Or something could come,
46:34you know, from the other side of the sun that we didn't see. There's all sorts of wonderful
46:38complexities when it comes to observing this this phenomena we call space weather. The winds and the
46:43storms, but in this case, winds of particles and magnetic storms, storms of magnetic chaos on the
46:48sun. It's a wonderful thing to think about that our our lovely gentle star up there is is actually
46:54very dramatic and and very volatile. Sitting here at the bottom of the Earth's atmosphere, we're not
46:59really aware that we're in a larger environment in space. And the dominant thing is the sun. You
47:05know, the sun obviously is the biggest thing in our solar system, the most important thing. The
47:09sun not only puts out a lot of light and heat, but it also puts out a wind of high energy particles,
47:14high energy protons and electrons, charged particles. We actually are bathed in this all the
47:20time. It interacts with our atmosphere. It creates the northern and southern lights. In some cases,
47:26it can even be a a risk, especially to our technology. We're quite well protected from
47:31these high energy particles by our atmosphere and also by the Earth's magnetic field. The Earth has
47:37a very strong magnetic field that surrounds our planet and protects us from the worst of this
47:41stuff. Even the astronauts up in the space station, they're actually close enough to
47:45the Earth that they're largely protected by this magnetic field. When you go out to the moon and
47:49farther away, that's when you're not protected by the Earth's magnetic field and you find yourself
47:54just basically exposed to this wind of high energy particles. A lot of people don't realize how
47:59significant that is and how much uh not only NASA, but Noah and other organizations all over the the
48:06planet are monitoring this. There is a fleet of satellites right now and I don't know exactly
48:11the number because it usually changes but we have some satellites that are orbiting the sun itself.
48:15We have some that are actually placed between the earth and the sun. There is a place that actually
48:21the the sun's gravity and the earth's gravity balances out. If you're between the earth and the
48:25sun, you're actually attracted equally to either one gravitationally and you stick a satellite
48:30right there and it doesn't take a lot of energy to actually keep it in that spot. So we have this
48:35kind of early warning system to see if there's something dangerous coming from the sun. And then
48:40we have all kinds of observatories both here on the earth on in on the ground and also space-based
48:45observatories that orbit the earth that just look at the sun continuously. We even have satellites
48:49around the solar systems look at different angles of the sun. So we we've got the sun covered. Now
48:53why is it so important? Well, the solar wind normally doesn't really have much danger to us,
49:00you know, or the environment in space. But when you're dealing with space weather, sometimes
49:04there's a really big line of thunderstorms coming through. Right? So in the case of the sun,
49:09the sun sometimes has very very violent storms. And these are storms caused by the the chaotic
49:15twisting magnetic field of the sun. Some of the hot gas on the surface of the sun actually gets
49:20accelerated so quickly by these magnetic fields that it just breaks off and takes off into space.
49:25And in one moment you could have trillions of tons of fast highmoving charged material coming
49:32out towards the earth. Now that's not actually very dangerous to us biologically. But what that
49:37can do is carry a huge amount of electrical and magnetic energy. All of a sudden all these charged
49:44particles hit the magnetic field of the earth and they can actually dump electric current right into
49:49our magnetic field. There was a famous event in the mid 1800s called the Carrington event.
49:54With the Carrington event, we really were just starting to have things like telegraph lines. Now,
50:00in order to get a telegraph to work, there has to be electric current on the wires. And normally,
50:04you would hook up your telegraph to a power generator, and that would create electric current,
50:07and you could send your signals. So, when this Carrington event occurred, there was so much
50:12electric current dumped into the Earth's field that you could actually start sending signals
50:17with no connection to power. And then eventually as the storm went on, some of the telegraph wires
50:22actually caught on fire just from a storm of magnetic and electrical energy. These particles
50:28coming from the sun. So these days, of course, you know, we know that this could happen again. Uh
50:34events like this are rare, but they they certainly will happen from time to time. So there are all
50:39kinds of organizations, you know, the uh like like FEMA, you all these disaster relief organizations
50:43that work with NASA and Noah to actually figure out what happens if we think that a a dangerous
50:49solar storm is imminent. Um in the case of all of our satellites up above the atmosphere,
50:54they're very at risk. So we can basically shut them down, put them to sleep for a little while.
50:58Of course, that that that energy burst will hit them and it may damage their detectors,
51:02but at least most of the electronics are shut down at the time and we can recover them hopefully. And
51:07then there may even be uh you know plans that are necessary to to shut down parts of power
51:12grids because I think the biggest danger of these things to us is that when they actually hit the
51:17earth's field you could have so much again energy in that magnetic field of the earth that it could
51:22you know fry our power grids. I mean think about how bad it would be if all the power on earth just
51:26went out because of one of these solar storms. I mean that that could conceivably cause billions
51:31or maybe even trillions of dollars of damage. So there are people rehearsing these scenarios. There
51:36are people uh you know trying to figure out how we would shut things down, how we would protect
51:39ourselves and then we have our fleet of satellites trying to observe the sun all the time and we
51:44would have probably about a day's notice as one of these big storms made its way through the sun. The
51:50sun we think of as putting off lots of light and you know light travels at the speed of light which
51:55takes about 8 minutes to get from the sun to us. But this isn't light. These are charged particles,
52:00protons and electrons. And although they may be moving millions of miles an hour, it still will
52:05take them about, you know, a day or more to get to the Earth. So, we will have some warning. But yes,
52:09I mean, all around you there are people monitoring space weather and getting ready for a big storm.
52:15You know, the thing that's really fascinating to me about asteroids is that they are kind
52:19of a preservation of the way the solar system was billions of years ago. This is really true.
52:24The solar system was once this kind of cloud of gas and dust and then under the forces of gravity,
52:29things started to clump together into smaller bits and then larger bits that eventually
52:34became planets. And planets like the Earth changed so much, right? I mean, the interior
52:39of our planet is molten. There's stuff that's melting down there. On the surface, you've got
52:43erosion and rain and wind. So, nothing is really the same as it was billions of years ago.
52:49But there were these little small building blocks that got left behind that actually never got
52:53made into larger things and they're pretty much unchanged for billions of years. So scientifically
53:00the reason these are such treasures is that they are kind of a a time capsule of what the
53:05chemistry the physical conditions everything was like as the solar system formed. The question of
53:11mining them. So the thing that happened with the earth is that the earth has this this hot molten
53:17core and most of anything that's heavy sinks to the bottom. Right? So when you have a liquid,
53:22heavier stuff sinks to the bottom. So the core of our planet is made of iron, you know, and nickel,
53:27but also metals like gold and silver and platinum, anything that was heavy when the Earth was molten
53:33would have mainly sunk to the core. So that means that if that didn't happen to an asteroid,
53:39an asteroid is still kind of all mixed up. The heavier stuff hasn't actually sunk out
53:44of it. Given a volume, there is in fact more rare elements, more gold, more platinum, more titanium,
53:50whatever. But asteroids are also fairly small and of course they're in space, so they're hard to get
53:55to. To me, it becomes kind of a a cost question. Yes, asteroid material by and large has more rare
54:02valuable elements than parts of our Earth's crust. It also has a lot more iron. You can get very
54:08expensive iron. I don't know when it will actually become economically feasible to go all the way to
54:14an asteroid, mine it, bring stuff back or however you want to do that to get the tiny little bit of
54:19gold that you'll get out of it. My guess is not soon. I don't think we will actually be mining
54:23asteroids in any real commercial way very soon at all. It's a fascinating question whether you could
54:29use a compass in space. So, let's talk first about compasses and then maybe talk a bit more
54:34about the idea of how we locate ourselves in space in general. A compass is something that responds
54:40to a magnetic field. So, the reason a compass always points north is that it's responding to
54:45the magnetic field of the Earth. Our planet has this wonderful core of molten metal. That metal
54:51moves around inside the Earth and it generates a magnetic field that has two poles, a north pole
54:55and a south pole. When you make a compass, you make it out of something metal that can respond to
55:00that magnetic field and it points to the magnetic pole of the Earth, which is very close to our
55:05north pole. A magnetic field directs compasses. Obviously, if you go away from the Earth,
55:11far away from our planet, it's no longer going to be able to feel our magnetic field. So, a compass
55:16will not point to the north pole of the Earth if, say, you're out by Saturn. Saturn and Jupiter are
55:21separate planets and they have magnetic fields of their own. So certainly if you were actually
55:25close to Jupiter, Jupiter has a magnetic field much stronger than the Earth's magnetic field.
55:30Your compass would definitely point to the north pole of Jupiter if you were actually
55:33around Jupiter. Now, but what if you get farther out? What if you actually go farther from there?
55:39Is there any magnetic field out in space itself? Well, actually, it turns out that there are that
55:44our galaxy does have a magnetic field as a whole, too. This magnetic field might be hard to detect.
55:49You might need a very, very sensitive compass, but say you had it. you would actually see that
55:54our galaxy does have sort of a magnetic north and south pole and that magnetic field permeates our
55:59whole galaxy. With compasses, you could actually at least find out where the north and south pole
56:04of another planet is, the north and south pole of a star. A star has a magnetic field, too. Even the
56:10north and south pole of a galaxy that's responding to a local magnetic field. But then it kind of
56:16begs the question, how do you find your direction in space that doesn't involve a magnetic field
56:20out between the galaxies where really there's no detectable magnetic field at all? Everything is
56:25moving. There's nothing to say this point is still and this is the reference point we're going to use
56:30and everything moves according to that point. We're moving around the sun at uh about 66,000
56:37miles an hour. Right now the sun is moving around the galaxy around the core of the galaxy at about
56:42half a million miles an hour. We are actually falling gravitationally into the center of a
56:47cluster of galaxies at about a million and a half miles an hour. That's just when we say relative
56:52to what? Relative to the sun. Relative to this group of galaxies. There is no absolute standard
56:58of reference in the universe. There is one thing that is perhaps the best way of navigating your
57:05way around the universe and that's something called the microwave background radiation. That's
57:09the farthest radiation we can possibly see. That's radiation that's coming everywhere in the universe
57:15from a time about 400,000 years after the Big Bangs. And it fills all of space with this gentle
57:22microwave radiation. And it's pretty much the same in every direction. In fact, if you had an
57:28old style television that used to have an antenna decades ago, a lot of the static that you would
57:32see on the screen was actually microwaves from this background radiation. And one of the things
57:37we can measure is our motion relative to this bath of radiation, the microwave background. So if you
57:44were trying to navigate with a compass in space, just remember that compass is going to respond to
57:49the strongest and closest magnetic field. It will point north, north to the pole of a planet, north
57:54to the pole of a star, even to the north and south magnetic poles of our galaxy. But what you're
58:00reading is a magnetic field. That's what a compass does. And that's pretty much all it can tell you.
58:05Well, this is the thing about the power of astronomy that kind of really does blow my mind
58:08is how much we actually do know. There's all kinds of things that we don't know and and astronomers,
58:14scientists in general tend to really focus on what we don't know because that's what we're
58:18working on. That's that's our jobs. That's that's how we get, you know, the grant money to sustain
58:22ourselves is trying to answer the questions that we don't know yet. But the things that we do know
58:28in some ways, just how recently we know them really kind of blow my mind. You think about
58:33what are stars made of, right? I mean, you've probably heard that stars are mainly made of
58:38hydrogen and helium. You know, they're these big sort of balls of gas, you know, very, very hot,
58:43dense burning balls of gas. But how long ago did we know that? It was actually really not until,
58:48you know, times like the 20s or 30s that a young woman named Cecilia Payne, uh, working at Harvard
58:53wrote a PhD dissertation pretty much proving they had to be made out of hydrogen. It was a graduate
58:58student, a woman graduate student. At the time, the idea was that the sun was probably something
59:03very much like the earth. It was like a big rock. And if you have a rock that big, and this is true,
59:09there would be so much gravity pushing it together that the temperature of the rock would
59:13be very hot. So, you know, the temperature of the surface of the sun is round about 10,000°. And if
59:20you had a rock that big with that much gravity pushing it together, it would be that hot. But
59:26it would only be that hot for probably a couple million years. And the neat thing was, you know,
59:31around about the late 1800s, it was Charles Darwin who had been looking at things like uh evolution,
59:36the strata of rock like the Grand Canyon, and he sort of had this this feeling that millions
59:42of years certainly was a long amount of time, but he didn't think it was long enough to for
59:46the changes that he saw in the earth itself. The prevailing idea, and this was a problem,
59:52is that the sun was basically a big earth. Gravity just just the contraction of gravity was making
59:57it hot. it would take millions of years to cool off. It turns out that wasn't it at all. It was
1:00:03actually made of hydrogen, the lightest substance in the universe. But now you have so much gravity
1:00:09crushing together the hydrogen making the interior very hot, millions of degrees hot, hot enough
1:00:15actually to start a nuclear fusion reaction and that can last billions of years. Certainly one
1:00:21of the biggest misconceptions is that people think that scientists feel that the big bang came out of
1:00:26nothing, right? I mean, how did all of this energy and all of this matter that made up the universe,
1:00:30you're saying it just came out of nothing? No. I I I don't think any scientist actually believes
1:00:35that. The problem is when you think about the condition the universe was in at that
1:00:40point where I mean take our observable universe, right? I mean, you can look from one side of the
1:00:45universe to the other back, you know, 13.5 billion lightyears or more. All of the stuff that we see
1:00:51was actually compressed into a space smaller than an atom, a volume smaller than an atom.
1:00:57We don't have the physics that describes how that would work. That is so much mass, so much energy
1:01:03in so little volume. I mean, at this point there wasn't even mass, just basically pure energy that
1:01:07right now our physics doesn't go there. As we get a better idea about how gravity works under very
1:01:14extreme circumstances, you huge energy densities, we may have some idea what set off the big bang
1:01:20and possibly what came before the big bang. And even that word is a little bit difficult when you
1:01:26start talking about the big bang because the big bang we believe was the creation not just of space
1:01:31but of time. Whatever state the universe was in before the big bang probably didn't have time as
1:01:38we perceive it either. Space and time appear to be some kind of a consequence that of the later
1:01:43expansion. So how do you describe something that doesn't have space and time that has huge amounts
1:01:48of energy and tiny little volumes? We don't have the physics. It's not that we will never know this
1:01:53but right now we don't have any way to describe it. Now another major misconception about the big
1:01:58bang is that the universe before the big bang was small. Okay. Now didn't I just say that everything
1:02:03we see in the universe was probably contained, you know, less than the volume of an atom. And
1:02:07didn't I just say that? Well, the thing is I know every scientist understands that we cannot see the
1:02:14entire universe right now. And that's because there's such a thing that we quantify as the
1:02:18observable universe. The universe has existed, we think since the big bang about say 13.8 billion
1:02:25years. So as you look farther and farther out into space, you necessarily have to look back
1:02:31in time. If something is a million lighty years away from you, like the Andromeda galaxy is about
1:02:36two million lighty years away. The light that you see through binoculars tonight as you look
1:02:41up at the Andromeda galaxy left two million years ago. You're seeing the Andromeda galaxy as it was.
1:02:46So today we actually have telescopes that are so powerful they can see back to a time about 400,000
1:02:51years after the Big Bang. That's amazing. We can see so far away in space that the light has taken
1:02:56that long to get to us. You know, nearly 13.8 billion years. And when we look back to that time,
1:03:02the universe looks very different. For one thing, it's very hot. It's actually about as hot as the
1:03:08surface of the sun. And it's so dense and hot that we actually can't see any farther. Literally,
1:03:14in any direction you look around the sky, anywhere you look, if you look to that distance, you see
1:03:20the universe as it was at that time, 400,000 years after the Big Bang, and everything becomes just
1:03:25hot hydrogen gas. So, I know this is kind of a strange way to uh to put it because we're talking
1:03:31about before the Big Bang, there may not have been space and time the way we think they are today.
1:03:35But whatever it was before the Big Bang, whatever was there, there was a tiny little part of it,
1:03:40a tiny little volume that expanded to become the universe we see today. But that little bit wasn't
1:03:46the whole universe. We don't know yet how big the original universe was, all of it, before the big
1:03:52bang happened, before something changed to make it expand and completely change its form. So the
1:03:58universe before the big bang didn't have to be necessarily tiny. It actually could be infinitely
1:04:03large. Because of that, we have no idea how big the universe is, what shape it has. All we can
1:04:09see is a tiny little bit of it. Think about my arm being the universe before the Big Bang. you know,
1:04:14in some kind of state that we can't even describe through modern physics. The entire
1:04:19observable universe that we can see now used to be a tiny volume of it, maybe an atom in my arm. One
1:04:27atom expanded and became the entire observable universe that we see. But that's not the whole
1:04:33universe. There are trillions of atoms in my arm. Each one of those could have expand to actually
1:04:40be its own entirely observable universe. So, we can't tell yet how big the universe was before
1:04:46the Big Bang or even what shape the universe is because all we're seeing is a tiny little
1:04:52bit of it that expanded to become everything that we see. But that's not the whole universe. That's
1:04:57our observable universe. There's far more out there than what we can see. One of the most
1:05:04common questions that I'm getting from the public these days is, is our universe a simulation? I I
1:05:10think that one of the things people are thinking about is they've heard the term the holographic
1:05:14universe and this is indeed a very powerful and increasingly popular idea in modern physics but
1:05:21it's a little bit unfortunately named and and let me sort of take you through this. This all started
1:05:26a couple decades ago when people like Stephven Hawking and others were trying to figure out how
1:05:30a black hole really works. We know black holes exist. We actually observe them from a distance
1:05:36very routinely. But the physics of how they work never quite worked. They appeared to violate some
1:05:41pretty important laws of physics. The universe doesn't like to lose information. A particle has
1:05:47a charge. It has a spin. There are all kinds of of things you can say about an elementary particle.
1:05:53But when it falls into a black hole, the only thing that seems to exist anymore is mass, the
1:05:58gravity that that particle had. What happened to the information about its charge? Can you ever get
1:06:03that back? As people began to do the mathematics a bit, they noticed something very intriguing
1:06:09that everything seemed to work much better if you assumed the black hole was twodimensional. Now,
1:06:15black holes are actually three-dimensional objects. You know, a lot of times they're
1:06:18portrayed kind of as things going down a drain, but basically you have a sphere, which is the
1:06:23point of no return. Gravity is so intense around a black hole that if you get anywhere this close,
1:06:28you never come back out. That's the event horizon of a black hole. So instead of assuming that it is
1:06:33a a sphere around the black hole, it all started to act like it was a two-dimensional surface,
1:06:39something that was three-dimensional became much more understandable if it was two-dimensional.
1:06:44And as scientists do, they thought, well, okay, if this works for a black hole, is it telling
1:06:48us something about the rest of the universe? And this may be one of the most important new
1:06:53revolutions in modern physics that the laws of physics might work a lot better, might actually
1:06:59work out together if you assume that our reality is really two-dimensional. You look around, there
1:07:05seems to be more than two dimensions in space and there's time. How would that work? The example
1:07:11of a hologram came up. You know, I still remember being at a hologram museum back in the 1980s. Uh,
1:07:17and the holograms were really new and really exciting. The idea that a hologram is made out
1:07:22of just a two-dimensional block of film or a block of glass, but it seems to be three-dimensional
1:07:28when you look into it. And even more than that, I remember this one hologram that was put on a
1:07:33pedestal and as you walked around the hologram, somebody appeared to move inside and wave at
1:07:39you. If you were looking at the hologram, there appeared to be motion and even time all embedded
1:07:44in just this two-dimensional surface. That's what they mean when they say holographic principle. It
1:07:49doesn't imply that anybody made a hologram or that we are part of a projection that somebody
1:07:54some evil genius is projecting reality on us. What the holographic principle really is is
1:07:59the universe may store energy in a way and information in a way similar to a hologram.
1:08:05If that's true and we really are embedded in this two-dimensional universe that has some
1:08:11pretty amazing repercussions. It probably means that every point in time exists at once. That,
1:08:17you know, our idea that things are changing and that I'm I'm moving right now and time is flowing
1:08:22in one direction. That's probably the same as somebody just walking by a hologram and having the
1:08:27perception that the image is moving. It's probably not real. The amazing idea is that the extension
1:08:34of space itself and time actually flowing may not be real intrinsic parts of the universe. They may
1:08:43be some way that we perceive it with the human brain, but in fact there's an underlying reality
1:08:48where that is not true. We say that these are emergent properties. It's not the real story.
1:08:54A hologram doesn't really move. A hologram is not really three-dimensional, but it seems so through
1:09:00our perception. That's an amazing idea that the entire universe exists all at once as some kind
1:09:06of surface of information. That's the holographic principle. It's working quite well right now. I
1:09:11can't tell you whether it's true or not, whether there there really is some real two-dimensional
1:09:16thing that we think of as the universe. So, stay tuned. At the time that Darren was doing this, I
1:09:22think there was sort of this argument between like biblical people that said the earth was a couple
1:09:25thousand years old and then the scientists said, "Oh, no, no, it must be millions of years old."
1:09:29What one of the things about being an astronomer is you throw around very very large numbers all
1:09:33the time. I mean, some of them are just kind of, you know, stupidly large. But even things
1:09:37like how many is a million, right? How many is a billion? The the human brain, I don't perceive
1:09:44that really any better than anybody else. The human brain just doesn't go there. Instead, you
1:09:48kind of find yourself getting used to swimming in an environment where your your mind can't really
1:09:54grasp all the way around a concept. It just can't. You I can't tell you how far away a lightyear is.
1:10:00I mean, one lightyear, you know, the distance light travels in one year at 186,000 miles per
1:10:05second. That's a close to about 6 trillion miles. I I don't have the ability to actually visualize
1:10:12that or feel it. And yet to me a lightyear seems very familiar and actually actually quite close.
1:10:18So maybe that's one of the reasons astronomers are almost kind of predisposed to being able to
1:10:23let go of sort of your common sense when people say things like the inside of a neutron star,
1:10:31you know, is is is so dense that a single teaspoonful, you know, of that material would have
1:10:36as much mass as Mount Everest. It's like, okay, the laws of physics pretty much require that. or
1:10:42when when people say what was the temperature of the universe just you know 3 seconds after
1:10:45the big bang that our physics really does work to to predict that. So I think that when you start
1:10:52swimming just in these big numbers and you begin to kind of let go of the idea that the human mind
1:10:57is the beall and endall. You know we have these tools to start attacking larger problems to start
1:11:03asking bigger questions. All of a sudden it comes very natural to say things like oh yeah you know
1:11:08gravity is actually a bending of space and time. The amazing thing about that is that that started
1:11:12out to be completely theoretical. You know, people thought that Einstein's theories were very useful.
1:11:18I mean, they made extremely accurate predictions about how the planets move, about how the universe
1:11:23works. But was there any really reality to the fact that space and time could bend? I mean,
1:11:29literally the space in front of me, the space and time around me can change and bend,
1:11:34even have a direction to it. It turns out that you know our theories for the most part do lead
1:11:40us to something really physically true. And you know right now people ask me questions like are
1:11:46there multiple universes? What's the shape of the universe? You know the larger universe? All of
1:11:50these things are wonderful questions and we don't know the answer to them yet. But I have a feeling
1:11:55that it's not just wasting time. You I think some of these stranger theories will bear themselves
1:12:01out over time. We just need to wait. Right now, I think it's a little bit too soon to follow them
1:12:05all the way into the rabbit hole. Let's say that there were many, many multiple realities. Well,
1:12:10how would physics work? How would this work? It's still too much conjecture for me to invest a huge
1:12:14amount in it. You know, I still remember, you know, what's only 2,000 years ago, unless that you
1:12:20had people like Aristotle who were brilliant and they came up with this idea that all the planets
1:12:25had to follow perfect spherical orbits around the Earth in the middle and they were on these crystal
1:12:29spheres that somehow moved and you know, people all the way up into the Renaissance were trying
1:12:33to figure out how those crystal spheres could have worked and how they were supported. Well,
1:12:38it turns out there weren't any crystal spheres. There's always a bit of me as an observational
1:12:42scientist that says, you know, take everything with a grain of salt for now. Oh, I mean, airsoft
1:12:46had this elegant, wonderful system. I mean, people loved it until the Renaissance, right? It's just
1:12:51that our observations didn't bear up with it. And it was so beautiful, people hated to let it go,
1:12:57but unfortunately, that's not how the solar system works. Definitely pursue these questions,
1:13:03but I'm not sure I'm ready to dive all the way into any of those rabbit holes quite yet. I love
1:13:08to think about them, but I think it's probably a little too soon to follow them ultimately
1:13:12to where they might go. So, people today have all these wonderful questions that that modern
1:13:16physics is leading us to. Questions like, are the way we perceive space and time real? That's
1:13:21even 100 years old. Albert Einstein said that space and time could be bent. Time itself could
1:13:26stop. Then there are things like the holographic principle. Is it possible that our whole universe
1:13:31is some sort of embedded information structure on a two-dimensional surface?
1:13:36These are amazing ideas and they may turn out to actually have some physical truth to them. We're
1:13:40not really sure yet. But sometimes people say, "Well, are you scientists just absolutely crazy?
1:13:46How is it that you so blightly get rid of the idea that time has a direction or that space is real?"
1:13:53One of the things you have to very deeply accept to be a scientist is that your senses,
1:14:00the human brain is just not the best instrument to perceive the entirety of the universe. I mean,
1:14:06let's take a simple example. There are many, many colors of light, energies of light that our eyes
1:14:12are not sensitive to. There are things like gamma rays and x-rays, ultraviolet light, radio waves.
1:14:18Those are all just different colors that our eyes don't see. The universe has colors that just
1:14:22weren't built for the human body to perceive. And when it comes to a mind, a brain. Think about some
1:14:29of the incredible creatures all around us. I mean, you know, think about a grasshopper, a marvel
1:14:35of evolution. It has a brain. It has a central nervous system. But could you teach a grasshopper
1:14:41quantum mechanics or general relativity? You know, could it compose a symphony or or write a novel?
1:14:46It just can't. I mean, a grasshopper's brain just doesn't have the complexity to do that.
1:14:51A grasshopper doesn't perceive those things. What about a bacterium? A bacterium doesn't even have
1:14:56a brain, but of course, the the majority of life on Earth by mass is still bacteria. You have to
1:15:02have this humility and remind yourself that it's possible that the human brain is just as far away
1:15:08from perceiving the way the universe really is as a grasshopper is to perceiving quantum mechanics.
1:15:13We are not some beall and endall of perception. The universe was not designed, not built to be
1:15:20comprehensible to the human mind. We only see a little bit of it through the filter of what our
1:15:26minds can ingest and how they do it. And so we think that there really is such a thing as space
1:15:31and time. You know, we we actually think that there is a past, present, and a future when in
1:15:35fact there may not be. And this goes all the way back to Galileo. You know when Galileo was around
1:15:42the idea that the earth had to be the center. God made it. So God must have put the earth
1:15:47in the center. But then it became proven that the earth went around a larger object, the sun. And I
1:15:53think almost more beautifully, one of my favorite observations of Galileo is that when he invented
1:15:57his little telescope, he he looked at the sky and he realized that there were stars in the sky you
1:16:02couldn't see with just the unaded human eye. There were stars up there that we were unable to see
1:16:08unless you looked through a telescope, a piece of technology. And the question was, why would
1:16:13the universe do that if the universe was designed for us to see and us to perceive? Why would there
1:16:18be things too far away and too dim for us to see? Why are parts of the universe so strange
1:16:24and so incomprehensible and make so little common sense? Honestly, why should it be any other way?
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