This thing is seemingly hovering in space and spinning around and defying gravity and I don’t know what all and I cannot wrap my brain around it (oh just go LOOK Quantum Levitation - YouTube)
I asked my physicist husband about it and he was all non-chalant like “The round thing is being leviated by magnetic force. But it’s doing it in a way that is stiff so it doesn’t just push or pull but does both at the same time so it holds it there, suspended in space. The square thing is a type of magnet that is magnetically stiff in all directions so it just holds the round thing where it is. The spinny thing and the track are only stiff in two directions so the round thing can spin or glide along the track. Get it?”
And I’m like: “Oh. Uh-huh, I TOTALLY understand that.” But, what?
I’ll admit I don’t understand most of this but apparently a magnetic field cannot penetrate through a superconductor. So the magnetic field flows around the superconductor and that holds the superconductor in place.
If you take two magnets and try to push their north poles together they repel each other. But because their magnetic fields are fixed in strength, its almost impossible to balance a normal magnet so that it floats above another magnet. It’s like trying to balance a pencil on its tip on a tabletop.
However, you CAN balance a pencil on its tip on your finger. By quickly moving your hand you can compensate for the inherent instability of the system. And, indeed, you can buy toys like this novelty globe that do the same thing with magnetism. There’s an electromagnet is the base that’s constantly adjusting its strength to exactly counterbalance the fixed magnet in the globe.
Now, an important thing to remember about magnetic fields is that they induce an electrical current in conductors that move through them, and vice versa. This is how electrical generators work. You spin a conductor in a magnetic field and electricity flows out. But, at the same time, the electricity flowing through the conductor generates an opposing magnetic field.
If you put a normal conductor near a magnet, it’s attracted. As it starts to move toward the magnet, a current is induced in the conductor that creates an opposing magnetic field that resists the movement. But because the conductor has resistance, the current dissipates as heat and the attraction continues.
But a superconductor doesn’t have any resistance. The induced current doesn’t dissipate. Instead it persists, creating a magnetic field that exactly balances the external field. It’s similar to the floating globe, but instead of an electromagnet that is constantly being tweaked by an electronic circuit, the superconductor acts like a self-adjusting electromagnet.
So if I understand correctly, the magnets are more or less ordinary, and it’s the disc that is special?
What is it made of? What’s that “steam” coming from it?
The item has been steeped in liquid nitrogen for a period of time before the demonstration. Liquid N2 exists at approximately -321 degrees F; the object may or may not be at -321F, but suffice it to say it’s pretty damn cold. The white fuzz you see on it is frost: atmospheric humidity condenses on the surface and freezes. The “steam” you see is fog, atmospheric humidity that has condensed into an airborn mist of droplets.
And of course, Israelis have extensive experience with cold temperatures.
Yeah, I’m amazed he’s not injuring himself, too. Even with only brief touches like that, I’d still want to be wearing gloves.
EDIT:
In principle, it could be used for full-sized vehicles, too. It’s just that, at present, the costs of the special track and the cooling systems outweigh the savings from having almost no friction. Folks are always trying to find higher and higher temperature superconductors, and the warmer they can get them, the more practical they become.
Room-temp superconductors will mean the advent of vehicles sliding along permanent-magnet roadways and railways with virtually no friction, needing only the energy necessary to overcome wind resistance.
Of course, I’d like to see the vehicle being able to “tune” its superconductor alignment so it can steer and change altitude. I can picture, for example, eastbound cars zooming along at twenty feet while westbound cars fly under them at ten feet, on the same road.
Room temperature superconductors? Do they have the status of “definitely doable, we just have to invent them” or “Maybe doable, kind of like cold fusion” or something else?
