Something weird happens when you keep squeezing

0:00 This is a syringe full of water. I've closed off this end so it can’t escape. And no matter how hard I push... Nothing really happens. I can't compress it. Even if I put this inside an industrial hydraulic press... a machine that can push down with thousands of tons of force... the volume would only decrease by about 1%. But what if it was squeezed even harder? What if this water was subjected to the extreme pressures in the Earth's core? Or inside the Sun? What would happen to it? The answer is something really bizarre. Something physicists are just starting to understand. In many ways, this is really a new field. We just don't fully know the rules yet. It's an entirely new regime of matter.

0:46 To try and wrap our heads around these extreme pressures and the way they warp physics as we know it. Let's go on a journey straight down. We'll start our trip up here on the surface at atmospheric pressure. How much pressure is that exactly? How does it compare to, say the pressure of my phone on my palm? Well, the phone's weight, about two Newtons... is spread out over about 100 square centimeters. That's how pressure is measured: A force distributed over an area. The pressure of the atmosphere the hundreds of miles of air above me... pulled down by Earth's gravity is 500 times stronger.

1:33 That's like the pressure my phone would exert on my palm if Dwayne “The Rock” Johnson was balancing on top of it. But because the air is free to flow around... it's also pushing up The Rock with the same pressure. Every phone sized patch of my body is getting pressed inward by the equivalent of The Rock's weight. Of course, all the structures and fluids within my body are pressing back and I'm so used to this equilibrium that I don't even notice. Before we leave these familiar conditions I'm going to grab a few things to take with us. A gram of hydrogen, a gram of sodium... and a kilo of water. We know exactly how these substances behave on Earth’s surface. But what happens when we start to squeeze? Just ten meters of seawater adds another whole atmosphere worth of pressure.

2:22 27 floors down... we pass the unassisted diving record. And just a little deeper... we hit ten atmospheres. Now we're going deeper than the deepest scuba dive. There's a blob of fish. They look like depressed jello on the surface but down here, the pressure keeps them trim. One kilometer down, we reach 100 atmospheres. The kinds of pressures we got with that giant hydraulic press. Sperm whales can dive this deep... and their hinged rib cages fold inward so the bones won't snap. Here, the Titan submersible was crushed... and here is the destination they never reached. [My Heart Will Go On by Celine Dion plays briefly] Somehow we're still passing fish.

3:07 And now we've reached the bottom of the Mariana Trench... and 1000 atmospheres. We're now up to the pressure of a phone with a herd of elephants balanced on top. Let's check in on the samples we brought. Our balloon of hydrogen gas has shrunk down to the size of a big marble. But both our solid sodium and liquid water haven't changed much. They're just barely compressed. Why is that? Well, the molecules of hydrogen had plenty of space between them. Room to shrink. But the sodium and water were already tightly packed. Even the pressure down here can't overcome the electrostatic repulsion between molecules. It's nowhere near strong enough. But let's keep going. Every meter of rock piles on the pressure nearly three times faster than water. The temperature is rising, too.

3:52 As we leave the crust, we hit 10,000 atmospheres. In the mantle, temperatures shoot past a 1000 degrees Celsius and some of the rock starts to melt. This is where many diamonds form. Carbon is squeezed into a tight crystal. As we go deeper into 100,000 atmospheres of pressure... the rock is compressed further, forced back into its solid form. Our sodium, meanwhile, has melted... and our bubble of hydrogen is liquid too. Compressed into a little clear globule. The water is also changing. It's getting squashed so much, it's forced to become a solid. But not the hexagonal crystals we get on the surface. Instead, it's a tighter cubic lattice. Scientists have found this variation of ice, Ice-VII... trapped inside diamonds.

4:39 As we get close to Earth's core we pass 1 million atmospheres. That's the equivalent of an oil tanker balanced on a phone. This is the threshold we're now leaving the world that physicists fully understand. This is where the external forces are about the same and starting to overwhelm the internal forces. The crushing pressure is starting to overcome the electromagnetic forces holding water molecules apart apart and maintaining their shape. The behavior that comes out of being in these extreme conditions is pretty bizarre. How do you study matter under conditions that normally only exist deep inside the earth? That was the point of creating the Center for Matter at Atomic Pressures. We're going to be doing all the fundamental physics

5:26 to be able to understand matter under these really different kinds of conditions. CMAP is headquartered at the University of Rochester... and they've got a tool that helps them create extreme pressures. The enormous Omega EP laser which fills this giant room. This is the facility's schedule. Scientists from around the world queue up for months just for a chance to blast a tiny sample of matter with a laser beam. And how do you feel in the run up to this? Unbelievably nervous. You spent a year of planning and crossing T's and dotting I’s... just to get to this point. The shot director gets on the intercom and he goes— Five... four, three... two, one. [silence] Shot 39607 is now complete.

6:14 That was it. During that split second, a million atmosphere pressures were momentarily created in the next room... the same pressures that exist deep within Earth. How does a beam of light do that? Let's go through it again. Just way slower. The laser beam is born in these machines down in the basement... and it's directed through a maze of lenses and devices that shape and monitor it. Bouncing through these massive tubes... it's infused with more power until it's as wide as this opening: About 45 centimeters across. Then it races towards the target chamber which is hidden behind this tangle of equipment. This is a visual representation of the target chamber.

7:00 And the target is right at the center of it. Those are really, like a pinpoint... on the tip of a pen, just absurdly small. The target is a tiny, inedible sandwich with a sample of whatever substance the researchers are interested in in the middle. The laser light is focused down to hit this first layer which explodes into a superheated ionized gas. And that plasma blows off of the surface like a rocket. Ahat creates this buildup of pressure that forms a shockwave. And that shockwave really quickly travels through the material. The last layer acts as a window allowing the passage of electromagnetic rays generated during the experiment. And then surrounding it you have these spaces to put different cameras

7:46 and other tools that we use to measure the various things that we're interested in. If you look through this porthole... you can see a couple of these sensors getting moved into place. In 2017, researchers put a tiny bit of Ice-VII sandwiched between two diamonds... in the target chamber. As the shockwave passed through it... pressure in the ice spiked above 2 million atmospheres and its atoms rearranged. Oxygens formed a tight lattice... while hydrogens were free to diffuse through it. It was Ice-XVIII, four times denser than normal ice... and able to conduct electricity almost as well as a metal. For a few billionth of a second... the laser had recreated conditions inside Earth. Speaking of, let's get back to our journey. As our water starts to turn into Ice-XVIII... our glob of sodium is undergoing its own transformation.

8:34 Under these pressures, scientists have seen it turn transparent. Now, what could account for this? Well, metals like sodium are shiny because they have a bunch of free-flowing electrons that can absorb and then retransmit light which we see as a reflection. What happens when you apply pressure to it is you're squeezing the electrons away from their atoms... and into these localized pockets. Trapped like that, the electrons can't interact with light... and so it just passes through. We've reached the center of the earth... but that's not the end because we can continue into pressures found inside larger plants. Tens of thousands of kilometers below Jupiter's surface... Physicists think hydrogen will go through another change becoming a shiny conductor of electricity.

9:22 It's thought that a lot of Jupiter is made up of this metallic hydrogen. We think of high energy density materials as completely inverting the periodic table so your metals become transparent and your transparent materials become metals... and all these gases become solids... And the universe holds higher pressures still. The center of Jupiter sees over 10 million atmospheres just about the highest pressure that the Omega laser can create. And now we're diving into the sun... where pressures rise over 100 billion atmospheres. The island of Manhattan balanced on a phone. We've seen extreme pressures, overwhelming the forces that keep molecules apart. But here within the sun, they can overcome the very glue that holds atoms together.

10:10 Here, individual hydrogen nuclei can be used to form helium... a process that releases energy. This is nuclear fusion: The ultimate source of all energy in our solar system. The reaction at the center of every twinkling star. If we could somehow recreate this process on Earth and keep it going... we would have a near limitless source of clean, cheap power. And researchers around the world are using giant lasers, including Omega... to study this possibility. This is all a relatively new frontier of physics. Scientists still have so many questions about the rules about how different elements and substances act and interact under different conditions... and how that might influence the evolution of planets...

10:55 and their ability to foster life. They'll keep chipping away at those unknowns... one split second experiment at a time. [Lump of Coal by Adam Cole] Hold me close... Squeeze me tight... Get together/ Up the pressure Feels so wrong/ but it feels so right... Break me down/ Then you make me whole... You want a diamond/ take your time and keep on tryin/ ‘cause I’m just another coal. I’m just another coal! [Lump of Coal by Adam Cole fades]