"The rapid progress true Science now makes, occasions my regretting sometimes that I was born too soon. It is impossible to imagine the height to which may be carried, in a thousand years, the power of man over matter. We may perhaps learn to deprive large masses of their gravity, and give them absolute levity, for the sake of easy transport. Agriculture may diminish its labour and double its produce; all diseases may by sure means be prevented or cured, not excepting even that of old age, and our lives lengthened at pleasure even beyond the antediluvian standard. O that moral science were in as fair a way of improvement, that men would cease to be wolves to one another, and that human beings would at length learn what they now improperly call humanity!"
-- Letter from Benjamin Franklin to Joseph Priestly (8 Feb 1780), quoted in "How Mumbo Jumbo conquered the World" by Francis Wheen
You can shell out 80 bucks and do it yourself: http://sargentwelch.com/superconductivity-suspension-and-lev... (LN2 not provided.)
There doesn't appear to be any novel physics here at all.
This isn't entirely accurate. A "chunk of type 2 superconductor" would just show the Meissner Effect, which is different than "flux pinning". The Meissner Effect is how superconductors essentially repel magnetic fields, resulting in levitation; it wouldn't necessarily pin the levitating body in-place such that it could follow some track for example.
Flux pinning occurs when some magnetic fields penetrate the superconductor in discrete "tubes" through the imperfections (along the grains) of the superconductor. In order for flux pinning to happen, you must have an extremely thin superconductor (in the case of the video, it's actually a sapphire crystal wafer with a 1-micron thick coating of superconductor ceramic material).
EDIT: Technically, you could also get flux pinning if you were to supercool the superconductor (i.e. make it a superconductor) while it's in the magnetic field of the magnet.
So, I'm quite curious on how this works ;) Is it because it's a very thin superconductor in this video?
If it's thin enough, it will float.
Then I saw some comment threads on various sites and I was like "okay, let's see what's going on here". Heh, cute levitation effect.
NSN or SN
I can't resist posting one of youtube's comments on this last video: "so... you have created the worst paperweight ever"
so people already wanna make a gun out of it, that's just sad
mankind will always pervert science for power?
In fact, maybe governmental science grants should have some sort of gladiatorial combat requirements for disputed priority...
The stuff of which awesome party tricks are made. I have myself put a very small amount of liquid nitrogen in my mouth and blown it out, although I then heard that the guy who taught me that trick (Jearl Walker) cracked a tooth doing that, so I never tried it again. And for the love of god do not swallow or you will literally kill yourself very painfully -- see footnote 3 of the above Wikipedia article.
I think I'll stick with dipping fingers briefly into LN, which is way less stupid. Done that many times. Do not get it on your clothing, though, because then you can't retreat quickly and the frost is going to bite!
Yet another example of how the web makes us much, much smarter.
I estimate that I used a tiny sip, not 3 or 4 ccs, but still. Crazy risky.
He actually grips the object, and I don't see extra smoke. When I have observed the Leidenfrost effect in the past, I see a noticable increase in outgassing, and the liquid (as it usually is) skitters about freely, so it seems like it might be difficult to grasp an object through the vapor layer.
Actually, are we sure the liquid nitrogen is actually hitting his hand? The point of contact is obscured by vapour. I mean, I'm familiar with the effect, but can also believe that a big stream of liquid nitrogen is gonna hit you and it's gonna hurt.
Believe it or not you can dip your hand in liquid nitrogen for 10 seconds without it freezing immediately and breaking off. I think carbon dioxide is solid at higher temperatures than nitrogen but I could be wrong on that one.
But when you do, doesn't it start to boil? This object seems to merely vaporize without doing so any faster when in contact with his fingers.
I just saw another video and you are right that they just cool it with liquid nitro.
A guy spoke up regarding his father who works in the field. Currently doing Q&A
Additionally, the author of the paper displays some worryingly crackpot-like symptoms. He claims that it's "Nobel worthy", (!!) but Citebase can find no citations.
I know nearly nothing about condensed matter physics, but skimming the paper reveals that his theory doesn't really make any testable predictions, much less the "grand slam" predictions that would result in a Nobel, like room-temp superconductivity.
Impact factor is tremendously flawed, but as a quick sanity check, when you're not sure if something makes any sense at all, it is of great use.
As far as crackpot symptoms, it looks like he's a biblical literalist too!
Or from a "cause-and-effect" viewpoint, movement of the magnet induces a current loop in the superconductor, the creation of which creates an opposing magnetic force.
Either way I believe this is the same principle behind electric motor braking (e.g. when you short-circuit the inputs of a motor). I believe you would also see a similar effect by dropping a magnet down a tube encircled with many (or perhaps one spiral) loop of wire -- the magnet's descent will be slowed by eddy currents in the loops.
Edit: Aha, this is just half the story. The superconductor is prevented from spinning due to flux pinning: http://en.wikipedia.org/wiki/Flux_pinning (or what the researchers call quantum trapping / quantum locking)
You can get clever with pulsed electromagnets and active coils, but eddy current braking works just fine with a permanent magnet and a thick piece of copper: http://www.youtube.com/watch?v=nrw-i5Ku0mI
...I really want to hear from an actual physicist about the "quantum trapping" explanation. I feel like I must be oversimplifying but I can't find any inconsistencies in my model.
"This levitation is NOT due to the Meissner effect. It is negligible since we use thin films. If it were the Meissner effect the field would get distorted on a length scale of the diameter (~cm) and then two discs hovering above and below each other would affect it other. Which is clearly not the case. The discs are actually trapped in constant field contours rather than levitating."
In the lab we succeeded in putting up to 0.5Kg on top of one disc. Keep in mind that the thickness of the superconducting layer is ~1micron ! Its a strong effect.
So if this was demonstrated live to congress, do you think they'd finally fund a few miles of super-conducting trains for research?
Can't help wondering if perhaps 50 years ago people were also getting excited about it and expecting to see cool things to come out of it in the near future.
Not saying that there couldn't, but I can't help feeling vary about the "technology of the future claim".
Well, no more so than everything else you might happen to see in your everyday life.
But: really cool video.
So ... this is actually real? If so, that's pretty awesome :)