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Ask Slashdot: How Would Room-Temp Superconductors Affect Us?
Bananatree3 writes "While we have sci-fi visions of room temperature superconductors like in the movie Avatar, the question still remains: How would the discovery of a such a material impact our everyday lives? How would the nature of warfare change? How would the global economy react? What are the cultural pros and cons of such a technological shift?" And just as important, in what contexts would you want to see it first employed?
Not really: radiative emission is the only type of cooling you can get in space. Depending how much power you're bleeding off elsewhere on your ship, it could be quite difficult to keep things suitably cool. Especially considering that any part of your ship facing the sun is going to be picking up quite a high thermal load.
Is it hell, space isn't cold, it is inert. I seriously wish people would stop thinking this.
The only way heat gets out of things in space is radiative or an infinitely small amount of conductive.
Direct sunlight on a person would burn them in space, likewise heating up metals and components.
Space is actually probably harder to cool things down in simply due to sunlight.
On earth it is pretty easy to have something in shadow and vented so that an incredible amount of heat is exchanged over to the flowing air.
In space, you can only rely on highly-resistant insulators and/or mirrors to get rid of heat unless you liquid cool things. (which is good too since you can then use that heat inside the ship)
100% computational efficiency, 0% heat release
You can't do that. Any non-reversible computation causes an increase in entropy, and reversible computation is not particularly practical. Achieving practical reversible computation would be a leap at least as large as room temperature superconductors.
Finally! A year of moderation! Ready for 2019?
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This is true but one of the great things about a superconductor is that R (and thus the power dissipated) goes to zero. So while it is difficult to dissipate heat in space, you won't be building up heat in the superconductors themselves.
Most people think of superconductors as merely a "perfectly efficient" conductor. While this is true, it just scratches the surface of what's possible with superconductors. Using superconductors just to improve efficiency wouldn't be that big a deal by itself. It would improve battery life a little bit, and maybe drop bulk electricity transmission overheads, but not by much, and certainly not immediately. Making most superconductors into high-tensile wire is a non-trivial exercise, even if cooling isn't a problem -- and it will be! Just because a material is discovered that can conduct at "room" temperature isn't helpful for wire outdoors in direct sunlight, or in a hot environment inside high-temperature machinery. Last but not least, superconductors have current and magnetic field limits that increase as they are cooled past the transition temperature. A superconductor with a transition temperature of 26C would probably have only a few limited applications above 20C.
The other uses are more interesting, and often more amenable to thermal control:
The Meissner_effect provides magnetic shielding, which is useful for all sorts of things, like amplifiers, or for protecting sensitive electronics. This is also what causes magnets to levitate above Type 2 superconductors. I assume that a room-temperature superconductor would be Type 2, so levitation would likely be possible.
The London moment could be used in gyroscopes and the like.
Josephson junctions provide all sorts of functions, like ultra-sensitive magnetic field sensors (think hard-drives and MRIs).
Still, all of that is a bit... meh. I mean sure, you get less noise in your now ultra-sensitive amplifier, and electricity will cost 10% less than it would have otherwise in 30 years. Is this life changing? Probably not really.
A much more interesting potential application than all of those combined is Rapid Single Flux Quantum digital circuitry. That stuff makes silicon look like vacuum tubes. Think 100GHz+, self-clocking, 1000x as efficient as CMOS, and manufacturable now, with only the cooling requirement the big down-side. If RSFQ could be made to work at room-temperature (or even near it), you could be looking at a sudden massive leap forward in computer power like never before. For example, with a power draw 1000x lower, it would be possible to stack every chip in a typical computer into a little "cube", with much shorter wire lengths, and hence, latencies. We can't do this now, because that cube would literally melt in seconds form the heat.
The reality-check of all this is that many MRI machines are still cooled by liquid helium, even though superconductors that work at liquid nitrogen temperatures have been available for a while. This tells you a lot about the limitations that might restrict the application of even a hypothetical room-temperature superconductor. For example, ultra-sensitive sensors and RSFQ may not work at all, because the tiny signal quanta may be swamped by the background thermal noise. Similarly, manufacturability of wire and maximum magnetic field strength is a key requirement for a lot of applications, like MRIs and electric motors.
Personally, I suspect that the first room-temperature superconductor will be initially manufacturable in bulk only as a thin-film, so expect the first decade or two to be mostly about improved circuitry and sensors more than anything else. This might be closer than people think. For example, there's a harmless quack who claims to have achieved superconductivity at 28C by manufacturing extremely complex copper-based crystals as a thin layer between two different traditional copper-based superconductors. Assuming for a second that he's onto something, it gives you an idea
No, superconductors are not thermally superconductive, just electrically. Niven made a mistake there.
In practice, you can cool satellites pretty darned far. WMAP is cooled to 90K passively. Planck is cooled to 50K passively. So yes, it is very possible to cool satellites to within the superconductivity range of modern high-temperature superconductors.
The inefficiency of modern digital circuits comes from two things:
1. Leakage through gate oxides (insulators) and switched-off transistors (semiconductor action).
2. Charging and discharging transistor gates during turn-on and turn-off (capacitance).
Unfortunately, superconductors won't help with either of those. Even switching power supplies lose a lot of power through transistor switching and diode drops. For most electronic products, imperfect semiconductor devices are a bigger problem than imperfect conductors.
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