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Video: Quantum Levitation
- skeletonjelly 15y agoWhen I came into work this morning this was at the top of reddit.com/r/all (got to get the procrastination out of the way first thing right!) A guy spoke up regarding his father who works in the field. Currently doing Q&A http://redd.it/lfsjn http://redd.it/lfsjn
- jmaygarden 15y agoIs there a layman's summary regarding the significance of that paper linked on reddit?
- sbierwagen 15y agoCompletely irrelevant. It's a theory explaining how Type II superconductors work, published five years ago, in a Chinese journal that has an impact factor of 0.512 (Nature scores 30.98, for comparison.)
- ehsanu1 15y agoWhat's the relevance of "impact factors"? I understand the basic idea behind them, but I don't think publishing research in a low impact factor journal should automatically make said research "completely irrelevant".
- sbierwagen 15y agoIt's completely irrelevant because it has little to nothing to do with the original post, much like how you wouldn't link to a paper on algorithmic complexity in a post about Facebook, because "they're both about computers." 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.
- blasdel 15y agoHe cited it himself in two other papers :/ As far as crackpot symptoms, it looks like he's a biblical literalist too!
- sbierwagen 15y agoAh ha, you missed my very careful weasel wording! I said that Citebase found no citations, not that it actually had no citations, mwa ha ha.
- fybren 15y agoThis is very cool. Another video with a bit of an explanation as to why - http://www.youtube.com/watch?v=VyOtIsnG71U http://www.youtube.com/watch?v=VyOtIsnG71U.
- andrewflnr 15y agoThanks. I'm not sure I understand the part about "quantum flux tubes". I take it that they're leaks through flaws in the superconductor (which should exclude the field entirely). Is the superconductor is being gripped or pinned by these lines of force running through it, like a piece of cheese on a toothpick? But that doesn't quite explain how it can move along a field.
- JangoSteve 15y agoI think the magnets on the track piece may be arranged NSN like this: NNNNNNNNNN SSSSSSSSSS ==> NNNNNNNNNN Which allows movement as indicated. In the part of the video where it's just locked stationary above a square magnet, it appears maybe the magnet as this arrangment: NNN NS NSN or SN NNN Which locks it entirely in-place, not allowing movement. And then in the part where it's spinning, I think maybe the magnet is S on the inside and N on the outside or something: NN NSSN NS SN NSSN NN Allowing it to spin. But this is speculation based on my limited understanding (but I noticed no one else was answering, so I thought I'd give a shot).
- chubs 15y agoVery good video. The 'locking' effect is simply blowing my mind. I had no idea that was possible.
- babebridou 15y agoI'm trying to figure out some practical applications for frictionless movement and positioning of small, light and cold objects without changing the scale of the system, but each of my ideas implies some heating that would probably negate the phenomenon a bit too fast (ballistics for instance). I can't resist posting one of youtube's comments on this last video: "so... you have created the worst paperweight ever"
- bgramer 15y agoHow much longer before we all drive landspeeders?
- jeffool 15y agoToo long.
- mattyohe 15y agoIs this "quantum locking" just a rebranding of the Meissner Effect? http://en.wikipedia.org/wiki/Meissner_effect http://en.wikipedia.org/wiki/Meissner_effect
- grannyg00se 15y agoQuoting a comment in the video linked to by fybren: "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."
- hugh3 15y agoNot particularly quantum mechanical. Well, no more so than everything else you might happen to see in your everyday life.
- marcamillion 15y agoFlying cars here we come?
- rcthompson 15y agoSure, but you can only fly at constant altitude along longitude lines. If I understand the effect correctly.
- michaelneale 15y agoThis would have to be over a magnetic surface - like maglev trains http://en.wikipedia.org/wiki/Maglev http://en.wikipedia.org/wiki/Maglev (which apparently are not technically trains).
- GraffitiTim 15y agoHow does this work?
- joshu 15y agoblogspam.
- morganpyne 15y agoAgreed. Several people (myself included) had already submitted the direct link to the youtube video. This blog adds absolutely nothing to the video.
- jasonadriaan 15y agonot exactly, I just posted it to tumblr. It would be blogspam if I were running ads, but I don't.
- JonnieCache 15y agoIt's still blogspam even if you're only craving attention.
- jeffool 15y agoOn a more serious note, I'd love to find out more about just how much weight they think this tech could support in the future. Those implications could be insane.
- geuis 15y agoAgreed. If the "floating" (I know its not actually floating in the traditional sense) object could carry its own light-weight cooling system then you wouldn't need to chill the entire unit to super cold temperatures. You might only need to cool the superconducting layer.
- Geee 15y agoThe thing is, we are all waiting for room temp superconductors. That paper on the Reddit post seems to have some breakthrough regarding this if I'm not wrong.
- XLcommerce 15y agofrom the comments 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.
- anigbrowl 15y agoLoads of up to 500 grams on this test rig, on what look to be about n40 magnets, according to the presenter's comment on one of the lab videos. The liquid nitrogen is a problem but that payload seems like something that could already have industrial applications.
- colanderman 15y agoSo, the electrical engineer in me says that this is because any movement of the magnet would induce an electric potential in the superconductor. But because such a potential would create an effectively infinite amount of current requiring an infinite amount of work, the magnet is unable to move. 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 http://en.wikipedia.org/wiki/Flux_pinning (or what the researchers call quantum trapping / quantum locking)
- andrewflnr 15y agoAnd it's able to move around the ring because from its perspective, the field isn't changing?
- colanderman 15y agoExactly. ...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.
- sbierwagen 15y agohttp://en.wikipedia.org/wiki/Eddy_current_brake http://en.wikipedia.org/wiki/Eddy_current_brake 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 http://www.youtube.com/watch?v=nrw-i5Ku0mI
- laughinghan 15y agoBut, it clearly does not take an infinite amount of force to move the "locked" superconductor, because you can adjust it by hand. The real question is, how much force does it take?
- latch 15y agohow much force (if any) is required to break it off the track? Could that disk be slingshotted around at hundreds of miles per hour and stay on tack?
- simcop2387 15y agoI'd imagine whatever force is needed is proportional to the strength of the magnets. Given that he can pull it off I can't imagine that specific setup requires all that much force for it.
- Pointsly 15y agoAm I really the first one who immediately thinks about Hoverboards???
- sliverstorm 15y agoQuick question: If the object is the temperature of liquid nitrogen, how can he touch it for so long?
- xutopia 15y agoThat does not look like liquid nitrogen. It's solid so that tells me it is carbon dioxide. 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.
- sliverstorm 15y agoI don't mean the object is nitrogen- I just think I caught them say it had been chilled with liquid nitrogen. 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.
- xutopia 15y agoYeah you feel it boiling on your fingers. It's really bizarre too because it feels all light compared to water. I just saw another video and you are right that they just cool it with liquid nitro.
- sbierwagen 15y agoIt's covered in water and carbon dioxide frost.
- mechanical_fish 15y agoLeidenfrost effect: http://en.wikipedia.org/wiki/Leidenfrost_effect http://en.wikipedia.org/wiki/Leidenfrost_effect 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!
- sbierwagen 15y agoPure marketing. "Quantum levitation" is just flux pinning[1] as seen in all "high temperature" superconductors. All you need a chunk of type 2 superconductor, a strong magnet, and some liquid nitrogen. Note the 852 videos on youtube: http://www.google.com/search?q=superconductor+levitation&source=univ&tbm=vid http://www.google.com/search?q=superconductor+levitation&... You can shell out 80 bucks and do it yourself: http://sargentwelch.com/superconductivity-suspension-and-levitation-kit/p/IG0038153/ http://sargentwelch.com/superconductivity-suspension-and-lev... (LN2 not provided.) There doesn't appear to be any novel physics here at all. 1: http://en.wikipedia.org/wiki/Flux_pinning http://en.wikipedia.org/wiki/Flux_pinning
- Geee 15y agoI thought first that this is the same old levitation effect, but apparently it's something new. At least the effect seems to be much stronger.
- sbierwagen 15y ago"Much stronger"? You can reposition it with your hand!
- martinkallstrom 15y agoIt's strong enough to not have the springiness you normally see with levitating superconductors.
- dhbanes 15y agoWhat's he marketing exactly? It's a Tel-Aviv University demo at ASTC.
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- altrego99 15y agoI think naming the device "Quantum Levitation" is marketing. Why can't the student call it what it is?
- ars 15y agoDirect link: http://www.youtube.com/watch?v=Ws6AAhTw7RA http://www.youtube.com/watch?v=Ws6AAhTw7RA
- ck2 15y agoWill this scale to train cars weighing a few tons each? So if this was demonstrated live to congress, do you think they'd finally fund a few miles of super-conducting trains for research?
- DanBC 15y agoIsn't there already a shortage of rare earth minerals, used to make strong magnets? Is that going to be a problem for extending uses of this outside a lab? But: really cool video.
- coldarchon 15y agothe universe is full of them ..
- kokey 15y agoYou could always use electromagnets.
- coldarchon 15y agoAt 1:30 the disc on the tracks stops without any outer interference, am I missing something in the video?
- camtarn 15y agoYeah - when I saw that after watching the Take This Lollipop video, which is an extremely well-done fake, I immediately lumped this one into the "cool special effects, but not real" category. So ... this is actually real? If so, that's pretty awesome :)
- vilda 15y agoIt's stopped with a finger. Watch carefully on the left side, frame by frame.
- zerostar07 15y agoQuantum physics professors do that in their first lecture, it's getting old.
- MarkMc 15y agoReminds me of a great quote by Benjamin Franklin: "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
- sans-serif 15y agoBenjamin Franklin would be delighted to know that he woefully underestimated science's impact on agriculture. http://en.wikipedia.org/wiki/File:Wheat_yields_in_developing_countries_1951-2004.png http://en.wikipedia.org/wiki/File:Wheat_yields_in_developing...
- Duckpaddle2 15y agoThat has to be one of the most engaging conferences I have ever seen. The science demos are just too cool. If I have the time I'm going next year!
- Tichy 15y agoHm, I remember getting excited about this about 23 years ago, when I was still at school. 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".
- DrData 15y agoPut this in a vacuum... perpetual motion?
- atte 15y agoAs a thought experiment, could the effect demonstrated here be used for a transport system on a much colder planet with a much stronger magnetic field (I do realize that these two properties tend to correlate in opposite directions)? What about in our arctic regions, potentially over a magnetic track to interconnect enclosed "settlements"? I'm guessing it would be less cost-effective than other types of transport if even possible, but many times cooler.