571–580 of 906 posts
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That looks like a chunk of pyrolytic carbon, which can also float above a magnet.
AFAIK doesn't pyrolytic carbon need a N-S field in order to levitate? That's the one key difference I can see - this looks like the traditional superconductor trick of just levitating in a simple field. i.e. not like some of the ones you'd see here: https://www.youtube.com/watch?v=Vy9uWXgbKy0
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And I think that's what we are seeing in the video. The eddy current effect isn't permanent like in superconductivity. They have to keep moving the magnet around.
Ah, that's not the video I saw. I was referring to this one : https://sciencecast.org/casts/suc384jly50n
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My favorite example is the hydrogen fuel cell. It was invented before the lead acid battery back in the 1800s. PEM gave it a boost around the Apollo era, but that wasn't enough to make it widespread either. Lead-Acid went through its whole 100+ year character arc and hydrogen fuel cells still haven't found product market fit. Sometimes that's how it is.
There are plenty of commercial applications of hydrogen fuel cells though. The biggest issue has been pretty much a constant over the time since it has been invented: keeping the membranes free from impurities is hard. But there are all kinds of transportation devices using hydrogen in production today.
Revolutionary tech does change normal peoples lives, and sometimes very rapidly, but a lot of stuff that looks revolutionary just kind of never works out.
I'd say nuclear power is probably the prime example of this. It was supposed to bring us electricity too cheap to meter, but it's actually the most expensive form of generation that anyone bothers to build.
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I've forgotten how many times one of the most important thresholds in our times has been bumped up a bit. Now we seem to be offered heaven on a plate. If superconductance can be reliably demonstrated at RTP (you wear a light cotton shirt, instead of 1cm thick fancy weaves involving an awful lot of rubber) then we are laughing all the way to ameliorating climate change. Even if this result is confirmed then I think it…
If the argument is that superconductivity = better efficiency = less energy use, then I am afraid that Jevon's Paradox has some bad news: https://en.wikipedia.org/wiki/Jevons_paradox
Ah, I see, they decided to start leaking some of the alien stuff they recovered from UFO crash sites in the 50s.
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> what we are doing is in fact to re-create conditions roughly on par with what is happening in the core of the sun My understanding is we are not. (Not an expert!) The Sun's core runs around 15 MK [1]. A tokamak, 150 MK [2]. Orders of magnitude rarely come for free in physics. We need those higher energies because we can't, like the Sun, swaddle with the mass of a hundred thousand worlds a low-temperature, low-frequ…
If you start to think of 'temperature' of individual particles as 'speed with which they move' that is a useful rough approximation of trying to figure out what it means that something has a particular temperature. Containing the plasma is hard not just because of the temperature it is at but simply because it tends to destroy anything that contains it and that doesn't really change all that much for 15 million degre…
It's also nice when your reaction quits flinging antimatter at your containment vessel :)
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They've just proven (if true of course) that it's possible at all. That is a massive, massive leap. And once it's possible, it won't be long until it's optimized. We've seen this everywhere -- transistors were once huge and now nanometers; solar cells have improved in every where; batteries are cheaper and better than ever.
Many years ago, as an undergrad, I was telling a grad student friend how I'd been learning about the Selection algorithm- it lets you pick the Kth largest element from an unsorted list in linear time, which is pretty neat. I said "It's O(n), but the constant is ridiculous in most implementations so it's usually better just to sort and then pick the kth element". The grad student friend said something that stuck with…
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Superconductivity is not enough for a cpu that doesn't generate heat, you would need a cpu built of reversible logic gate. Thermodynamics requires that when you destroy a bit of information you generate at least 2.9×10−21 J. It's the Landauer's principle.
Say we use this (or any other) superconductor to build an AND gate. Assume one input is zero, so the information of the other input is lost. I assume the energy lost as heat occurs due to the "current" going into the and gate having "nowhere else to go" other than to dissapate as heat? If that's the case, simply redesigning our logic gates to have as many outputs as they have inputs, with some of these outputs feedin…
Not quite, it's a thermodynamic principle that applies to any way you could possibly compute AND. Basically, the laws of physics are reversible, so your computation must be reversible too. There are 4 possible inputs to an AND gate, so to be reversible there must be 4 possible outputs, one for each input. But we only want one output for the rest of our computation, so the other one dump into the environment somehow.
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If you start to think of 'temperature' of individual particles as 'speed with which they move' that is a useful rough approximation of trying to figure out what it means that something has a particular temperature. Containing the plasma is hard not just because of the temperature it is at but simply because it tends to destroy anything that contains it and that doesn't really change all that much for 15 million degre…
> What it does change is that at 150 million degrees Celsius you have some hope of extracting useful work from a very small quantity of plasma It's also nice when your reaction quits flinging antimatter at your containment vessel :)