The levitating superconductor
-
0:10 - 0:14The phenomenon you saw here for a brief moment
-
0:14 - 0:20is called quantum levitation and quantum locking.
-
0:20 - 0:24And the object that was levitating here
-
0:24 - 0:26is called a superconductor.
-
0:26 - 0:32Superconductivity is a quantum state of matter,
-
0:32 - 0:36and it occurs only below a certain critical temperature.
-
0:36 - 0:39Now, it's quite an old phenomenon;
-
0:39 - 0:40it was discovered 100 years ago.
-
0:40 - 0:42However, only recently,
-
0:42 - 0:45due to several technological advancements,
-
0:45 - 0:47we are now able to demonstrate to you
-
0:47 - 0:51quantum levitation and quantum locking.
-
0:51 - 0:57So, a superconductor is defined by two properties.
-
0:57 - 1:01The first is zero electrical resistance,
-
1:01 - 1:07and the second is the expulsion of a magnetic field from the interior of the superconductor.
-
1:07 - 1:10That sounds complicated, right?
-
1:10 - 1:13But what is electrical resistance?
-
1:13 - 1:19So, electricity is the flow of electrons inside a material.
-
1:19 - 1:23And these electrons, while flowing,
-
1:23 - 1:25they collide with the atoms, and in these collisions
-
1:25 - 1:28they lose a certain amount of energy.
-
1:28 - 1:33And they dissipate this energy in the form of heat, and you know that effect.
-
1:33 - 1:39However, inside a superconductor there are no collisions,
-
1:39 - 1:44so there is no energy dissipation.
-
1:44 - 1:47It's quite remarkable. Think about it.
-
1:47 - 1:52In classical physics, there is always some friction, some energy loss.
-
1:52 - 1:56But not here, because it is a quantum effect.
-
1:56 - 2:05But that's not all, because superconductors don't like magnetic fields.
-
2:05 - 2:09So a superconductor will try to expel magnetic field from the inside,
-
2:09 - 2:15and it has the means to do that by circulating currents.
-
2:15 - 2:18Now, the combination of both effects --
-
2:18 - 2:24the expulsion of magnetic fields and zero electrical resistance --
-
2:24 - 2:27is exactly a superconductor.
-
2:27 - 2:32But the picture isn't always perfect, as we all know,
-
2:32 - 2:39and sometimes strands of magnetic field remain inside the superconductor.
-
2:39 - 2:43Now, under proper conditions, which we have here,
-
2:43 - 2:48these strands of magnetic field can be trapped inside the superconductor.
-
2:48 - 2:54And these strands of magnetic field inside the superconductor,
-
2:54 - 2:57they come in discrete quantities.
-
2:57 - 3:00Why? Because it is a quantum phenomenon. It's quantum physics.
-
3:00 - 3:04And it turns out that they behave like quantum particles.
-
3:04 - 3:10In this movie here, you can see how they flow one by one discretely.
-
3:10 - 3:14This is strands of magnetic field. These are not particles,
-
3:14 - 3:18but they behave like particles.
-
3:18 - 3:22So, this is why we call this effect quantum levitation and quantum locking.
-
3:22 - 3:28But what happens to the superconductor when we put it inside a magnetic field?
-
3:28 - 3:33Well, first there are strands of magnetic field left inside,
-
3:33 - 3:37but now the superconductor doesn't like them moving around,
-
3:37 - 3:40because their movements dissipate energy,
-
3:40 - 3:43which breaks the superconductivity state.
-
3:43 - 3:48So what it actually does, it locks these strands,
-
3:48 - 3:53which are called fluxons, and it locks these fluxons in place.
-
3:53 - 4:00And by doing that, what it actually does is locking itself in place.
-
4:00 - 4:09Why? Because any movement of the superconductor will change their place,
-
4:09 - 4:11will change their configuration.
-
4:11 - 4:16So we get quantum locking. And let me show you how this works.
-
4:16 - 4:22I have here a superconductor, which I wrapped up so it'd stay cold long enough.
-
4:22 - 4:26And when I place it on top of a regular magnet,
-
4:26 - 4:30it just stays locked in midair.
-
4:30 - 4:34(Applause)
-
4:34 - 4:38Now, this is not just levitation. It's not just repulsion.
-
4:38 - 4:43I can rearrange the fluxons, and it will be locked in this new configuration.
-
4:43 - 4:47Like this, or move it slightly to the right or to the left.
-
4:47 - 4:55So, this is quantum locking -- actually locking -- three-dimensional locking of the superconductor.
-
4:55 - 4:57Of course, I can turn it upside down,
-
4:57 - 5:00and it will remain locked.
-
5:00 - 5:09Now, now that we understand that this so-called levitation is actually locking,
-
5:09 - 5:14Yeah, we understand that.
-
5:14 - 5:18You won't be surprised to hear that if I take this circular magnet,
-
5:18 - 5:22in which the magnetic field is the same all around,
-
5:22 - 5:28the superconductor will be able to freely rotate around the axis of the magnet.
-
5:28 - 5:34Why? Because as long as it rotates, the locking is maintained.
-
5:34 - 5:40You see? I can adjust and I can rotate the superconductor.
-
5:40 - 5:47We have frictionless motion. It is still levitating, but can move freely all around.
-
5:47 - 5:56So, we have quantum locking and we can levitate it on top of this magnet.
-
5:56 - 6:02But how many fluxons, how many magnetic strands are there in a single disk like this?
-
6:02 - 6:05Well, we can calculate it, and it turns out, quite a lot.
-
6:05 - 6:13One hundred billion strands of magnetic field inside this three-inch disk.
-
6:13 - 6:17But that's not the amazing part yet, because there is something I haven't told you yet.
-
6:17 - 6:22And, yeah, the amazing part is that this superconductor that you see here
-
6:22 - 6:30is only half a micron thick. It's extremely thin.
-
6:30 - 6:39And this extremely thin layer is able to levitate more than 70,000 times its own weight.
-
6:39 - 6:45It's a remarkable effect. It's very strong.
-
6:45 - 6:49Now, I can extend this circular magnet,
-
6:49 - 6:54and make whatever track I want.
-
6:54 - 6:58For example, I can make a large circular rail here.
-
6:58 - 7:05And when I place the superconducting disk on top of this rail,
-
7:05 - 7:09it moves freely.
-
7:09 - 7:18(Applause)
-
7:18 - 7:23And again, that's not all. I can adjust its position like this, and rotate,
-
7:23 - 7:29and it freely moves in this new position.
-
7:29 - 7:34And I can even try a new thing; let's try it for the first time.
-
7:34 - 7:40I can take this disk and put it here,
-
7:40 - 7:43and while it stays here -- don't move --
-
7:43 - 7:49I will try to rotate the track,
-
7:49 - 7:51and hopefully, if I did it correctly,
-
7:51 - 7:54it stays suspended.
-
7:54 - 8:03(Applause)
-
8:03 - 8:10You see, it's quantum locking, not levitation.
-
8:10 - 8:14Now, while I'll let it circulate for a little more,
-
8:14 - 8:18let me tell you a little bit about superconductors.
-
8:18 - 8:23Now -- (Laughter) --
-
8:23 - 8:30So we now know that we are able to transfer enormous amount of currents inside superconductors,
-
8:30 - 8:35so we can use them to produce strong magnetic fields,
-
8:35 - 8:41such as needed in MRI machines, particle accelerators and so on.
-
8:41 - 8:45But we can also store energy using superconductors,
-
8:45 - 8:47because we have no dissipation.
-
8:47 - 8:54And we could also produce power cables, to transfer enormous amounts of current between power stations.
-
8:54 - 9:03Imagine you could back up a single power station with a single superconducting cable.
-
9:03 - 9:08But what is the future of quantum levitation and quantum locking?
-
9:08 - 9:15Well, let me answer this simple question by giving you an example.
-
9:15 - 9:21Imagine you would have a disk similar to the one I have here in my hand,
-
9:21 - 9:25three-inch diameter, with a single difference.
-
9:25 - 9:30The superconducting layer, instead of being half a micron thin,
-
9:30 - 9:33being two millimeters thin, quite thin.
-
9:33 - 9:44This two-millimeter-thin superconducting layer could hold 1,000 kilograms, a small car, in my hand.
-
9:44 - 9:47Amazing. Thank you.
-
9:47 - 10:03(Applause)
- Title:
- The levitating superconductor
- Speaker:
- Boaz Almog
- Description:
-
How can a super-thin, three-inch disk levitate something 70,000 times its own weight? In a riveting, futuristic demonstration, Boaz Almog shows how a phenomenon known as quantum locking allows a superconductor disk to float over a magnetic rail -- completely frictionlessly and with zero energy loss.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TEDTalks
- Duration:
- 10:25
Thu-Huong Ha edited English subtitles for The levitating superconductor | ||
Thu-Huong Ha approved English subtitles for The levitating superconductor | ||
Thu-Huong Ha accepted English subtitles for The levitating superconductor | ||
Thu-Huong Ha edited English subtitles for The levitating superconductor | ||
Morton Bast added a translation |