How the Universe Works - S07E01 - Nightmares of Neutron Stars
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00:00Neutron stars, super heavy, super dense, extreme, gravitational, magnetic, hot, scary.
00:19They destroy planets.
00:22They can even destroy stars.
00:25A cosmic conundrum.
00:27They're very, very massive, but they're also really, really small.
00:32Tiny cosmic superpowers long overshadowed by black holes, until now.
00:40Neutron stars have been thrust very much to the forefront of modern astrophysics.
00:44The world's astronomers know that something is happening.
00:48Something's up.
00:49It's new and it's different.
00:51Neutron stars are the most interesting astrophysical object in the universe.
00:58Now firmly in the limelight, neutron stars, creator of our most precious elements and
01:05life itself.
01:21130 million light years from Earth, a galaxy called NGC 4993.
01:34Two dead stars trapped in a rapidly diminishing spiral.
01:46It's like listening to the ringing of the cosmos itself, the sound of that collision,
01:50if you will, imprinted on the fabric of space and time itself.
01:55Livingston, Louisiana, the Advanced LIGO Observatory.
02:02Its mission, to detect gravitational waves generated in space.
02:09Gravitational wave is a distortion of space time that's caused by usually some kind of
02:13very traumatic gravitational event.
02:17Events such as supernovas or the collision of black holes were massive stars.
02:242015, LIGO makes history by detecting gravitational waves for the first time, 100 years after
02:34Einstein's prediction.
02:36It's the signature of the crash of black holes.
02:42It's almost like listening to the sound of a distant car crash that you didn't witness.
02:47But you're so clever and the sound of this car crash is such a unique signature that
02:52you are able to use your computers to model exactly the type of cars that must have collided
02:58together.
03:00Then in 2017, LIGO picks up a different kind of signal.
03:06The unfolding of the August 2017 event was nothing short of extraordinary.
03:11So the signal comes in and the signal is strange.
03:15It has a long lasting signal.
03:18It's over 100 seconds.
03:19Less than two seconds later, a gamma ray telescope detected a flash of gamma rays from that same
03:26part of the sky.
03:27And very quickly, the world's astronomers know that something is happening.
03:32Something's up.
03:33It's new and it's different.
03:38This combination of a long gravitational wave signal and a blaze of gamma rays acts as a
03:47beacon for astronomers.
03:51When they saw this event, they sent out a worldwide alert to astronomers across the
03:56globe saying, hey, we saw something interesting and it came from a particular patch of sky.
04:03Then all the chatter started amongst the astronomical community and everyone's starting
04:08pointing their telescopes at this one part of the sky.
04:12Within hours, thousands of astronomers and physicists across the globe are frantically
04:18collecting data on this mysterious event.
04:22There's not just the gravitational waves.
04:25There's not just the gamma rays.
04:26There's the visible light.
04:27There's infrared light.
04:28There's ultraviolet light.
04:30And all these signals together tell us a story.
04:34And this was the very first time we've seen these two multiple messengers at once.
04:39Gravitational waves and regular light.
04:41So that was a groundbreaking moment for astronomy.
04:49Scientists realize this isn't another black hole collision.
04:53This is something different.
04:55When you see an explosion in the universe, there aren't exactly a lot of candidates.
05:00There's not a lot of things in the universe that blow up.
05:06But the length of the signal is the smoking gun.
05:09The collision of two black holes was quick.
05:13This one was the longer, slower death in spiral of two neutron stars.
05:22Coming in closer and closer, speeding up.
05:25And then when they finally collide, when they finally touch, releasing a tremendous amount
05:29of energy into the surrounding system.
05:34The collision throws up huge clouds of matter, which may have slowed down the light very
05:39slightly.
05:40The light and gravitational waves travel for 130 million years, arriving at Earth almost
05:47simultaneously.
05:50It's the first time astronomers see neutron stars collide.
05:55They call it a kilonova.
05:58And this spectacular cosmic event doesn't just release energy.
06:03The aftermath of this neutron star collision, this kilonova, created a tremendous amount
06:07of debris, which blasted out into space.
06:10And this may finally have provided us the evidence of where some very special heavy
06:15elements are created.
06:17Through the destruction of a neutron star comes the seeds for the essential ingredients
06:23of life itself.
06:25We breathe oxygen molecules, O2.
06:29Water is hydrogen and oxygen.
06:31Most of our body is made up of carbon compounds that include nitrogen, phosphorus.
06:36One of the big questions in science over the history of humanity has been, what are the
06:42origins of these elements?
06:44And it turns out that neutron stars play a critical role in creating many of the heavy
06:50elements.
06:54Most of the elements on Earth are made in stars.
07:00But how the heaviest elements are made has been one of science's longest running mysteries.
07:08For a long time, we knew there was a problem with making these heavier atoms.
07:12Things like gold and platinum, you know, all the way out towards uranium.
07:15And really the most energetic thing we had in the universe was supernova explosions.
07:19So they had to be created somehow in supernovas.
07:23But when scientists ran computer simulations, virtual supernovas failed to forge these oversized
07:29atoms.
07:32In 2016, astronomer Edo Berger explained a potential solution to the mystery.
07:43If you open any one of these books and flip to the page that tells you where gold came
07:48from, it will tell you that gold came from supernova explosions.
07:57But it was becoming clear the textbooks were out of date.
08:06To form heavy elements requires a lot of neutrons.
08:09And so another possible theory was that the heaviest elements were produced in the mergers
08:14of two neutron stars in a binary system.
08:17But at the time, no one had actually seen a neutron star collision.
08:22It was difficult to convince the community that this was a potential channel for the
08:26production of heavy elements.
08:28The proof is to actually see this process happening in the universe.
08:34The 2017 kilonova provides the perfect opportunity.
08:39It generates thousands of hours of data.
08:44Scientists notice a pattern, subtle changes in the color of the kilonova remnants.
08:51In space, when you have an event that is very bright, it emits a certain amount of light
08:55and it emits it at certain wavelengths, what we think of as colors.
08:59Different colors in a pyrotechnics display indicate the use of different chemicals in
09:05fireworks.
09:06In the same way, scientists can uncover the elements in the kilonova by the colors in
09:11the explosion.
09:14As the kilonova turns red, they realize it's the result of newly created heavy elements
09:20starting to absorb blue light.
09:23Once we watched this remnant change, the explosion change in color, expand and cool,
09:29we could estimate what sort of elements were being produced.
09:34The light from the debris shifts from blue and violet to red and infrared.
09:40The color change provides clues about the presence of certain heavy metals.
09:54Well this neutron star collision, this kilonova, produced brightness and a color spectrum that
10:00are consistent with models of predictions that produce gold and platinum.
10:08This model is called the R-process, short for rapid neutron capture.
10:14That is a bit of a complicated term that describes how we make atoms heavier than iron.
10:20You need a really neutron-rich environment, and as you might imagine, a neutron star collision
10:25is a very neutron-rich environment.
10:27If these models are correct, and this blows me away, this collision, this kilonova, produced
10:34several dozen times the mass of the Earth in just gold.
10:46The 2017 kilonova not only reveals the origin of key elements, it sheds light on the neutron
10:54star's interior, the strongest material in the universe, creating a magnetic field a
11:01trillion times greater than that of Earth.
11:18Two neutron stars caught in a death spiral.
11:24This massive kilonova explosion not only sheds light on the creation of heavy elements such
11:29as gold and platinum, it also provides scientists with a unique insight into one of the most
11:36mysterious objects in the universe.
11:39Trying to imagine what a neutron star is really like really challenges our imagination.
11:44It also challenges our theoretical physics.
11:46We have to go to our computer models, our mathematics, to have some estimate of what
11:50this might be like.
11:53Now scientists don't have to rely on their imaginations.
11:58They can use hard data from the kilonova to work out what makes neutron stars tick.
12:10There's so much information we got from observing that one single event, that one colliding
12:13neutron star pair.
12:15Now for the first time we have an accurate estimate of the mass of the neutron star and
12:19the diameter.
12:20We can finally begin to piece together how neutron stars really work.
12:25To calculate the diameter is just 12.4 miles, one mile less than the length of Manhattan.
12:34Nailing down any physical characteristic is really important and if there's going to be
12:38one, the radius is a big one because from there, if you know the mass, you can get the
12:43density.
12:44If you know the overall density, you can start to figure out what the layering inside of
12:47a neutron star is like.
12:54For physicists, the interior of a neutron star is one of the most intriguing places
12:59in the universe.
13:00You have to realize that the conditions inside a neutron star are very, very different than
13:05the conditions that exist here on Earth.
13:07We're talking about material that's so dense that even the nuclei of atoms can't hold together.
13:12With a neutron star, you're taking something that weighs more than the sun and compressing
13:17it down to be smaller than a city.
13:20It's so dense that if you tried to put it on the ground, it would fall right through
13:24the Earth.
13:27High density means high gravity, gravity 200 billion times greater than on Earth.
13:35Imagine climbing up on a table on the surface of a neutron star and jumping off.
13:38You're going to just get flattened instantly and just spread out on that surface.
13:43So don't even think about trying to do push-ups.
13:47Added to the intense gravity are hugely powerful magnetic fields, awesome x-ray radiation,
13:55electric fields 30 million times more powerful than lightning bolts, and blizzards of high
14:01energy particles.
14:04For a space traveler, this is not a good neighborhood.
14:11If you were to find yourself in the vicinity of a neutron star, it's going to be bad news.
14:17First, you would be torn apart by the incredibly strong magnetic fields.
14:22Then the x-ray radiation would blast you to a crisp.
14:27And as it pulled you closer, its intense gravity would stretch out your atoms and molecules
14:33into a long thin stream.
14:35You would build your speed faster and faster and you'd finally impact the surface, splatter
14:41across it, and that process would release as much energy as a nuclear bomb.
14:50If I had the choice between falling into a neutron star versus a black hole, I think
14:55I'd pick the black hole because I don't really feel like being torn apart by a magnetic field
14:59and blasted with x-rays.
15:06On a cosmic scale, neutron stars may be pint-sized, but they sure pack a serious punch.
15:13The secret to all this pent-up power is what's going on below the surface.
15:20Armed with the new kilonova data, we can now take a virtual journey into the heart of a
15:26neutron star.
15:27First, we must pass through its atmosphere.
15:31Now it's not like the Earth's atmosphere, which goes up like a hundred miles.
15:34On a neutron star, the atmosphere is about this deep, and it's extremely dense compared
15:40to the air around us.
15:43Below the compressed atmosphere is a crust of ionized iron, a mixture of crystal iron
15:49nuclei and free-flowing iron electrons.
15:53Now the gravity is so strong that it's almost perfectly smooth.
15:57The biggest mountains on the surface are going to be less than a quarter of an inch high.
16:01A quarter-inch mountain range may sound odd, but things get even stranger as we go below
16:10the surface.
16:13This is home to the strongest material in the universe.
16:21It's so weird, scientists liken it to nuclear pasta.
16:27As we dive beneath the crust of a neutron star, the neutrons themselves start to glue
16:31themselves together into exotic shapes.
16:34First, they form clumps that look something like gnocchi.
16:40Then deeper, the gnocchi glue themselves together to form long strands that look like spaghetti.
16:47And then deeper, the spaghetti fuse together to form sheets of lasagna.
16:53And then finally, the lasagna fuse together to become a uniform mass, but with holes in
16:59it, so it looks like pennant.
17:03This is pasta, nuclear style.
17:06Simmering at a temperature of over a million degrees Fahrenheit, extreme gravity bends,
17:12squeezes, stretches, and buckles neutrons, creating a material 100,000 billion times
17:20denser than iron.
17:22But the journey gets even more extreme.
17:26Even deeper is more mysterious and harder to understand.
17:29The core of a neutron star, which is very far away from these layers, which we call
17:34the nuclear pasta, is perhaps the most exotic form of matter.
17:39So exotic, it might be the last bastion of matter before complete gravitational collapse
17:46into a black hole.
17:50Data from NASA's Chandra Observatory suggests the core is made up of a superfluid, a bizarre
17:57friction-free state of matter.
18:01Superfluids produced in the lab exhibit strange properties, such as the ability to flow upwards
18:08and escape airtight containers.
18:12Although our knowledge of the star's interior is still hazy, there's no mystery about its
18:16dazzling birth.
18:18Forged into life during the most spectacular event the universe has to offer, the explosive
18:24death of a massive star.
18:38Neutron stars, Manhattan-sized, but with a mass twice that of our sun.
18:47So dense, a teaspoon of their matter weighs a billion tons, mind-blowing objects that
18:55arrive with a bang.
18:57Neutron stars spark into life amid the death of their parent star.
19:01They're the ultimate story of resurrection or life from death.
19:07It's all part of a cosmic cycle.
19:11Stars are born from giant clouds of very cold gas.
19:15Those clouds collapse under their own gravity and the density of the core at the center
19:20of that collapse starts to increase.
19:27A star is a huge nuclear fusion reactor.
19:31The force of its gravity is so powerful that it fuses atoms together to make progressively
19:37heavier and heavier elements.
19:40The star fuses hydrogen into helium.
19:44Once it exhausts its hydrogen, then if it's massive enough, it can start fusing helium
19:48at its core.
19:52Fusion continues, forming carbon, oxygen, nitrogen, all the way up to iron.
19:59Once a star has iron in the core, it's almost like you've poisoned it because this extinguishes
20:07the nuclear reactions in the core of the star.
20:09You fuse something into iron and you get no energy.
20:14All of a sudden, there's nothing to support the crush of gravity.
20:17No radiation pressure pushing out means no pressure keeping the outer regions from falling
20:22in and that's what they do.
20:25As the star collapses in its death throes, its core becomes the wildest, craziest and
20:31freakiest pressure cooker in the whole universe.
20:36The ingredients are all in place.
20:40Time to start cooking up a neutron star.
20:45If we were to scale up an atomic nucleus to be the size of a baseball, in a normal atom,
20:51the nearest electron would be way over in those trees.
20:56But in the extreme conditions that lead to the formation of a neutron star, those electrons
21:01can be pushed closer to the nucleus.
21:04They can come zipping in from any direction.
21:07If the temperatures and pressures are high enough, they can even strike the nucleus and
21:12enter it and they can hit a proton.
21:15When they do, they become converted into more neutrons.
21:20In the formation of one of these objects, the protons and electrons disappear and you're
21:24left with almost entirely pure neutrons with nothing to stop them from cramming together
21:30and filling up this entire baseball with neutrons leading to incredibly high densities.
21:38With the sea of electrons now absorbed into the atomic nuclei, the matter in the stars
21:44can now press together a lot tighter.
21:48It's like squeezing 300 million tons of mass into a single sugar cube.
21:55As the star collapses, enormous amounts of gas fall towards the core.
22:02The core is small in size, but huge in mass.
22:06Billions of tons of gas bounce off of it, then erupt into the biggest fireworks display
22:12in the cosmos.
22:16A supernova.
22:18It's massive.
22:19It's bright.
22:20It's imposing.
22:22Supernovae are among the most dramatic events to happen in the universe.
22:26A single star dying, one star dying, can outshine an entire galaxy.
22:37And arising out of this cataclysm, a new and very strange cosmic entity.
22:46When the smoke finally clears from the supernova explosion, you're left with one of the most
22:49real, fascinating, unbelievable monsters in the entire universe.
22:55Humans have been witnessing supernovas for thousands of years, but we're only now just
22:59starting to understand what we've truly been witnessing.
23:03The births of neutron stars.
23:07But while supernovas are big and bright, neutron stars are small, and many don't even give
23:14off light.
23:16So how many neutron stars are out there?
23:20We know of about 2,000 neutron stars in our galaxy, but there probably are many, many
23:25more.
23:26I'm talking about tens of millions in the Milky Way alone, and certainly billions throughout
23:30the universe.
23:34Neutron stars may be small, but some give themselves away, shooting beams across the
23:40universe, unmistakable pulsing strobes of a cosmic lighthouse.
24:01Our knowledge of neutron stars is expanding, fast.
24:08But we didn't even know they existed until a lucky discovery just over 50 years ago.
24:15Cambridge, the Mullard Radio Observatory, Jocelyn Bell, grad student, operating the
24:21new radio telescope, scanning the sky, doing all sorts of cool astronomy stuff, and sees
24:28what she calls a bit of scruff in the data.
24:33This scruff is a short but constantly repeating burst of radiation originating a thousand
24:39light years from Earth.
24:42It's so stable and regular that Bell is convinced there's something wrong with her telescope.
24:48She returns to that spot and finds a repeating regular signal, a single point in the sky
24:57that is flashing at us continually, saying hi, hi, hi.
25:02Blip, blip, blip, boom, boom, boom, pulse, pulse, pulse.
25:09Nothing that we know of in the universe has such a steady, perfectly spaced in time pulse.
25:15It seems so perfect that it must have been artificial.
25:19It looks like someone is making that, but it turns out it's not a person, but a thing.
25:26What she discovered is called a pulsar.
25:32A pulsar is a type of rapidly spinning neutron star.
25:39Neutron stars had been theorized in the 1930s, but were thought to be too faint to be detected.
25:47Neutron stars were hypothesized to exist, but not really taken seriously.
25:54It was just a, oh, that's cute, maybe they're out there, but probably not.
26:00The signal Bell detected seemed like something from science fiction.
26:06No one had ever seen this in astronomy before, and some people even speculated that it was
26:11an alien signal.
26:13She even called them LGM objects, little green men.
26:19Then Bell found a second signal.
26:24Little green men went back to being fiction, and pulsars became science fact.
26:31The discovery of pulsars came out of the blue, nobody was expecting this.
26:35So it was an amazing breakthrough, really important.
26:41Pulsars pulse because they're born to spin.
26:46They burst into life as their parent star collapses during a supernova.
26:54Any object at all that is undergoing any sort of compression event, if it has any initial
26:59angular momentum at all, it will eventually end up spinning.
27:06As the star shrinks, it spins faster and faster.
27:11They spin so quickly because the Earth-sized core of a massive star collapsed to something
27:18as small as a city.
27:20So because the size of the object became so much smaller, the rate of spin had to increase
27:26by a tremendous amount.
27:29Neutron stars can spin really, really fast.
27:32Their surface is moving so fast, it's moving at about 20% the speed of light in some cases.
27:39So if you were to get on the neutron star ride, no pregnant women, no bad backs, no
27:45heart issues, keep your arms and legs inside the ride at all times because they are about
27:49to be obliterated.
27:51And as they spin, they generate flashing beams of energy.
27:58This beam is like a lighthouse beam.
28:01You see these periodic flashes many times per second.
28:04So every time you see it, beam, beam, beam.
28:09These beams are the pulsar's calling card.
28:12They're generated by the elemental chaos raging inside a neutron star.
28:18Although the star is predominantly a ball of neutrons, the crust is sprinkled with protons
28:23and electrons, spinning hundreds of times a second, generating an incredible magnetic
28:29field.
28:31And with the strong magnetic field, you can create strong electric fields and the electric
28:36and magnetic fields can work off of each other and become radiation.
28:41These neutron stars send jets, beams of radiation out of their spinning poles.
28:48And if their spinning pole is misaligned, if they're a little bit tilted, this beam
28:54will make circles across the universe.
28:57And if we're in the path of one of these circles, we'll see a flash, a flash.
29:03Just like if you're on a ship and you observe a distant lighthouse on a foggy night, you
29:08can see pulsars across the vast expanse of space because they are immensely powerful
29:13beams of light.
29:15But sometimes pulsars get an extra push that accelerates the spin even more.
29:22The way you make it spin even faster is by subsequently dumping more material onto it.
29:28That's called accretion.
29:29And you end up spinning it up even faster than it was already spinning.
29:32Like stellar vampires, pulsars are ready to suck the life out of any objects that stray
29:38too close.
29:40Gravity is bringing that material in, which means that any spin it has is accelerated.
29:45It spins faster and faster.
29:48These millisecond pulsars spin at around 700 revolutions per second.
29:53They are the ultimate kitchen blender.
29:55They will chop, they will slice, they will even julienne fry.
30:03So what stops neutron stars from simply tearing themselves apart?
30:08Neutron stars are incredibly exotic objects with immense, immense forces that bind them
30:14together.
30:15So they can be held rigid even against these incredibly fast rotation speeds.
30:20They have incredibly strong gravity, and this is what allows them to hold together even
30:27though they're spinning around so fast.
30:32The speed of the spin is hard to imagine.
30:38On Earth, a day is 24 hours long.
30:40On a neutron star, it's a 700th of a second long.
30:46Super-speeding pulsars are not the only weird stars that scientists are coming to grips
30:50with.
30:51There is one other type of neutron star that has the most powerful magnetic field in the
30:56universe.
30:58This magnetic monster is called a magnetar.
31:13Astronomers monitoring pulsing neutron stars have noticed something very odd.
31:19On very rare occasions, they can suddenly speed up.
31:24That's amazing.
31:25I mean, you've got this incredibly dense object and suddenly it's spinning faster.
31:29It happens instantly.
31:31They'll suddenly change frequency.
31:33It would take an amazing amount of power to do that.
31:36What's doing it?
31:38These sudden changes in speed are called glitches.
31:42One leading idea for what causes these glitches is that the core material latches onto the
31:47crust and this affects the way it can spin around.
31:50But there's another possible explanation.
31:53Glitches could also be caused by starquakes.
31:56This process releases a tremendous amount of radiation, a blast of x-rays, causes the
32:03face of the neutron star to rearrange itself and for the rotation speed to change.
32:10These starquakes release energy trapped inside the neutron star.
32:16Sometimes the crust gets ruptured.
32:19Anything that basically changes the geometry of the pulsar can change the rate at which
32:24it spins.
32:26So what could be powerful enough to cause these starquakes?
32:31It's hard to believe that there's any force in the universe that could deform the matter
32:35inside of a neutron star, which is undergoing tremendous gravity.
32:40When it comes to a neutron star, there's one thing that can do it, it's magnetism.
32:45Extreme magnetic fields within the star can get so twisted they can rip the crust wide
32:50open.
32:51And so the surface can restructure itself and constantly reshape.
32:56And just a tiny reconfiguration of the surface of a neutron star on the order of a few millimeters
33:02would be associated with an enormous release of energy.
33:07The neutron star's immense gravity smooths over the star's surface almost immediately.
33:13It's like the glitch never happened.
33:20When it comes to neutron stars, there is no end to magnetic mayhem.
33:27Meet the reigning champion in the universal, strongest magnetic field competition, the
33:34magnetar.
33:36One in ten neutron stars formed during a supernova becomes a magnetar.
33:42The thing about magnetars, as is implied in their name, the magnetic field on them is
33:47so strong that even somebody who is used to using big numbers, like say an astronomer,
33:53is still kind of in awe of these things.
33:57Magnetars have a magnetic field 1,000 trillion times stronger than that of Earth's.
34:03This amount of magnetism will seriously mess up anything that comes close.
34:09Any normal object that we're familiar with, if it got close to a magnetar, would just
34:14be shredded.
34:15Any charged particle that with any movement at all would just be torn from its atom.
34:19It would be just an insane situation.
34:24Magnetars burn brightly, but their lives are brief.
34:27We think magnetars, these intensely magnetized neutron stars, can only be really short-lived.
34:33Their magnetic field is so powerful that it should decay over very rapid timescales only
34:38on the order of a few 10,000 years.
34:41It seems their very strength leads to their downfall.
34:45That magnetic field is so strong that it's picking up material around it and accelerating
34:49it.
34:50Well, that acts like a drag, slowing it down.
34:52But over time, the spin of the neutron star slows and the magnetic field dies away.
35:00During their lives, magnetars operate very differently than pulsars.
35:04They don't have beams.
35:06Their magnetic fields shoot out gigantic bursts of high-intensity radiation.
35:13But recently, astronomers have spotted one neutron star that's hard to classify.
35:19It behaves like a stellar Jekyll and Hyde.
35:25So this particular neutron star is a really weird example.
35:28It behaves both like a radio pulsar and also a highly magnetized magnetar.
35:33It has the extreme magnetic fields.
35:36It can have these magnetic outbursts.
35:39But it also has this strong jet of radiation coming out of its poles.
35:43It's almost like it has a split personality.
35:47First sighted in 2000, this star was emitting radio waves, typical pulsar behavior.
35:53Then, 16 years later, it stopped pulsing and suddenly started sending out massive X-ray
36:01bursts, the actions of a magnetar.
36:06Scientists were baffled.
36:09We don't know if this thing is a pulsar turning into a magnetar or a magnetar turning into
36:13a pulsar.
36:15One theory is that these X-ray bursts happened because the star's magnetic field suddenly
36:21twisted.
36:22The stress became so great, the star cracked wide open, releasing the X-rays from the fractured
36:28crust.
36:29A neutron star is the densest material that we know of in the universe.
36:35And yet we've seen things that actually make it shift and pull apart.
36:38This neutron star is actually ripping itself apart under the forces of the magnetic field.
36:43If this is the case, placid neutron stars turn into raging magnetars, growing old disgracefully.
36:52When you think about the life cycle of a human being, we seem to kind of slow down over age,
36:56become a little more calmer.
36:58Neutron stars do the opposite.
36:59They can be spinning faster than they were when they were formed, and the magnetic field
37:03can get stronger over time.
37:05It's sort of a reverse aging process.
37:09But these strange changes are extremely rare.
37:12Neutron pulsars are as regular as clockwork.
37:16Pulsars are normally incredibly regular.
37:18You can literally set your watch to the timing of their pulse.
37:22And it's this stability that we may use in our future exploration of the universe.
37:28You know, if you're a starship captain, what you need is a galactic GPS system.
37:32Well, it turns out neutron stars may be the answer.
37:42Astronomers often compare the steady flash of spinning neutron stars, called pulsars,
37:52to cosmic lighthouses.
37:55These flashes are not only remarkably reliable, each pulsar has its very own distinct flickering
38:01beam.
38:04Each one has a slightly different frequency.
38:06Each one has a slightly different rate.
38:09Anyone in the galaxy, no matter where you are, can all agree on the positions of these
38:15pulsars.
38:19The unique signature of pulsars opens up intriguing possibilities for the future of space travel.
38:30We would basically be using pulsars to be able to sort of triangulate where we're at.
38:36And because those pulses are so precise, we can use that in a similar way that we use
38:40GPS satellites that are stationed above the Earth.
38:46Using pulsars as navigational aids is not a new idea.
38:51It was recognized by the NASA Voyager mission in the 1970s.
38:57Affixed to the surface of those spacecraft is a golden record.
39:01And on the plate that covers that record is a pulsar map, which in principle could tell
39:06an advanced alien civilization how to find Earth.
39:10Because it uses the position of Earth relative to 14 known pulsars as effectively a way to
39:15triangulate the position of our planet relative to all of these pulsars.
39:21Aliens haven't made contact, but NASA still uses pulsar maps.
39:27NASA recently launched a satellite called NICER Sextant that exists on the International
39:32Space Station that is being used to test these types of theories.
39:39They've used pulsars to figure out the location of an object orbiting around the Earth at
39:4917,000 miles an hour, and they were able to pinpoint its location to within three miles.
39:54That's pretty incredible.
39:57By recognizing their position relative to known pulsars, future space missions could
40:03navigate the universe.
40:11Neutron stars are going to take us on this incredible journey.
40:14Something as necessary as knowing where you are in the galaxy.
40:17We could be many hundreds of light years away, but neutron stars can actually show us where
40:21in the Milky Way we are.
40:30I read a lot of science fiction, and I love the idea of being able to go from star to
40:35star, planet to planet.
40:37It's kind of weird to think that in the future, as a galactic coordinate grid, we might wind
40:44up using these gigantic atomic nuclei, these rapidly spinning, bizarrely constructed, magnetic,
40:52fiercely gravitational objects like neutron stars.
40:59Neutron stars have come a long way since being mistaken for little green men.
41:07Once overlooked as astronomical oddities, they've now taken center stage as genuine
41:14stellar superstars.
41:18What's really exciting about neutron stars is that we're at the beginning of studying
41:22them.
41:23We're not at the conclusion.
41:24We've learned a lot, but there's a lot more to be learned.
41:27From the humble neutron comes the most powerful, the most rapid, the strongest magnetic field,
41:35the most exotic objects in the cosmos.
41:38I love the idea of a phoenix, something actually rising from its own ashes.
41:43You think something dies, and that's the end of the story.
41:45But something even more beautiful, even more fascinating comes afterwards.
41:49I told you at the beginning and you didn't believe me, but now I hope you do.
41:53Neutron stars are the most fascinating astrophysical objects in the universe.