Why room-temperature superconductors need extreme pressure

HostWe often hear about a future where power lines never get hot and batteries last for weeks because electricity flows with no resistance at all. But the materials we have found that actually work at the heat of a normal room come with a massive catch. Why is it that the only things we have found that work this way need to be squeezed harder than the dirt at the center of the planet?

GuestIt's a bit of a trade off. For a long time, the only way to get this kind of perfect flow was to make things colder than deep space. We had to use liquid helium to get metals down to a few degrees above absolute zero. In the last few years, we have finally found stuff that works at temperatures where you could wear a t-shirt, but only if you crush that stuff between the tips of two diamonds. You're basically trading a deep freeze for a giant squeeze.

HostBut when I think of room temperature, I think of my kitchen. If I have to put my kitchen inside a giant press that mimics the weight of the Earth's core, it doesn't really feel like it's happening at room temperature anymore.

GuestWell, in the world of physics, they separate those two things. Temperature is about how much the atoms are shaking. Pressure is about how close together those atoms are packed. We found that if we take a gas like hydrogen and mix it with a metal like lanthanum, we can get that perfect flow at a nice, warm temperature. But hydrogen is very light and flighty. It doesn't want to sit still. To force it to act like a solid metal and help the electricity move, you have to push it together so hard that the atoms have no choice but to link up. We're talking about millions of times the pressure of the air around us right now.

HostThis sounds more like a lab trick than a real breakthrough. If you need two diamonds to crush a speck of dust just to make it work, how's that ever going to help us build a better power grid?

GuestIt's a fair point, but it proves that the physics can actually happen. For decades, people thought it might be impossible to ever get this effect without extreme cold. Now we know it's possible. The reason we use that massive pressure is to create a very specific kind of bridge for the electrons. Think of electrons like people trying to run through a crowded room. Usually, they bump into the furniture, which is the atoms of the wire. Those bumps create heat, which is why your phone gets warm when you use it. But in these special materials, the atoms shake in a very specific way that lets the electrons pair up and glide through like they're on ice. The pressure is what stiffens those atoms so they can provide that smooth ride.

HostSo the pressure is basically acting like a cage to keep the atoms from moving too much?

GuestSort of. It's more like tightening the strings on a guitar so they vibrate at a much higher pitch. Hydrogen is the lightest atom there's, so it can shake very fast. If you squeeze it hard enough, those fast shakes help the electrons bond together even when it's warm out. Without that squeeze, the heat would just knock the electrons apart and the whole thing would stop working. We use diamonds for this because they're the only things strong enough to hold that much force without shattering. We take two tiny diamonds with flat tips and crank them together until the stuff in the middle is being crushed by the weight of several skyscrapers.

HostBut there must be a way to keep that state without the diamonds. I mean, we make diamonds in labs by using high pressure, and they stay diamonds once we take them out. Why can't we just lock this material into that state and let it be?

GuestThat's the big question everyone is trying to solve right now. Some things are what we call metastable. Like you said, a diamond is just carbon that got squeezed, and it stays a diamond at normal pressure. But most of these room temperature superconductors act more like a spring. The moment you let go of the pressure, the atoms just pop back to their old, lazy state and the magic disappears. We're looking for a material that's sticky enough to stay in that high pressure shape even after the diamonds are gone. It's like trying to find a way to glue the atoms in place while they're being crushed.

HostIt feels like we're still missing a piece of the puzzle. If hydrogen is the key because it's light, why don't we see this in other light materials that are easier to handle?

GuestHydrogen is unique because it's so simple. But it's also a gas, which is why it's so hard to pin down. Some researchers are trying to find ways to bake that pressure into the chemical bonds themselves. Instead of using a giant machine to push from the outside, they're trying to find atoms that naturally pull on each other with that same kind of intensity. If we can find a mix of elements that creates its own internal pressure, we could've a wire that works on your desk without the diamond press.

HostSo the goal is to make the atoms do the heavy lifting themselves.

GuestExactly. We're looking for a chemical structure that acts like a pre-tightened spring. We have seen some hints that adding things like carbon or nitrogen into the mix might help stabilize the structure. The dream is to find a recipe where the atoms just naturally lock into that perfect, stiff grid. If we find that, we go from a lab curiosity to a world where we could fly trains on magnets and never lose a single spark of power as it travels across the country.

HostWe're essentially trying to trick the atoms into thinking they're still at the center of the Earth while they're sitting on a shelf in a warehouse.

GuestThe real test is whether we can find a path to that state that doesn't involve the massive squeeze first, because right now, even if we made the perfect material, we still have no way to manufacture it at scale.

HostThe diamonds might show us the path, but they're clearly a very expensive set of training wheels.

GuestThe sheer force needed to make these materials work is the only thing standing between us and a world with perfectly efficient power.

HostThose diamonds are holding a tiny piece of the future, but they're also holding it back.

GuestLanthanum and hydrogen might be the first ones to work at room heat, but they're still waiting for us to find a way to let go of the squeeze.

HostThe pressure in those labs might be as high as the Earth's core, but it's the pressure to find a way out of the diamonds that's really driving the science.

GuestWe have proven the heat works, now we just have to prove we can do it under the open sky.

HostPower lines in the sun would finally stay as cool as the air around them.