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Quantum states & graphene

Foxbat

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Seems to me that in practical terms, this could be the next step in miniaturisation of electronic components.
 

dannymcg

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The ultimate layman (me!) wonders why they've been waffling on about graphene and how great/super/smashing it is for well over a decade but, as yet, has anything practical been produced?

Back in about 2008 there was gonna be phone batteries that charged in a few minutes and would run for 3+ days...Fermi says "where are they?"
 

Venusian Broon

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The ultimate layman (me!) wonders why they've been waffling on about graphene and how great/super/smashing it is for well over a decade but, as yet, has anything practical been produced?

Back in about 2008 there was gonna be phone batteries that charged in a few minutes and would run for 3+ days...Fermi says "where are they?"
Well the article actually states that nothing really new has been found. Although you'd think something had been from the headline.

It's the fractional quantum hall effect, something that got the nobel prize for physics in 1998, so it's reasonably old...however I think this is worth an article because it was observed in graphene, whereas before it was observed in some weird set ups.

If it's been observed in graphene, then potentially we can use it in some pretty robust situations. Graphene has loads of great properties, so if we could build stuff with it, we can now, I assume, throw in this fractional quantum hall effect. But...

Why haven't you seen much coming from it?

Well, to go back and look at other weird science (at the time) Faraday was doing public lectures, in the 1850s, demonstrating his findings in electricity and (I think) a member of parliament asked him 'what was use of all this new science'. He replied, "one day, you'll tax it.". It's going to take a while, I think, before graphene/fullerene enters actual products and devices, but eventually (assuming civilisation doesn't destroy itself) this will come through. Not ten years - there's a lot of stuff still to work out - but we're on the way. I think it's probably a bit like Nuclear fusion. It should be great when we figure that out properly and really change our world for the good.

Nuclear fusion is a bad example, it's constantly been 50 years till it will 'work'. For the past fifty years. But I do think it will eventually work.
 

Foxbat

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Another layman here but I've been reading that fusion wouldn't work without quantum tunneling. The argument being that even the high pressures and temperature are not enough to overcome the strong nuclear force that would act against protons being forced together. If this is the case, and given that quantum tunneling is a random process, it would seem to me that we will most likely never achieve fusion with the quantities we are currently using (greater numbers normally negate randomness to such an extent that it will provide enough events of this nature to make it feasible). The only way I can see to achieve this is to increase the amount of raw material. Maybe that's why stars are the size they are....or am I just talking nonsense?
 

Venusian Broon

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Another layman here but I've been reading that fusion wouldn't work without quantum tunneling. The argument being that even the high pressures and temperature are not enough to overcome the strong nuclear force that would act against protons being forced together. If this is the case, and given that quantum tunneling is a random process, it would seem to me that we will most likely never achieve fusion with the quantities we are currently using (greater numbers normally negate randomness to such an extent that it will provide enough events of this nature to make it feasible). The only way I can see to achieve this is to increase the amount of raw material. Maybe that's why stars are the size they are....or am I just talking nonsense?
I couldn't tell you how close or far away they are at the moment. They have made it work, at least in experiments, and they are upscaling it to make a more useful 500MW reactor. Apparently to start operating in 2027. And yes part of the design was to, from memory, increase the volume of the tokamak four times, from the previous design.

Stars are big because they use gravitational confinement to initiate thermonuclear fusion. And you need a lot of mass. Thankfully mass likes to accumulate into big blobs. But as we've seen we can use magnetic fields to almost get there. (I think it is controlling the plasma that is really awkward and has been the issue that has been holding up commercial use.)

But I don't think it necessary to have huge masses. We can already cause uncontrolled thermonuclear fusion with something with the mass of mere tons. We call them Hydrogen bombs. ;)

And there are a number of other ways that may bear fruit.

Yes, I think you are right, in that it's hard to smash atoms together to make bigger atoms, but...the most stable nuclei in the universe is iron, so any atoms heavier than iron are more-or-less unstable and prefer to fission down in size, and any atoms smaller, if given the chance, would actually like to bulk up. From an nucleus energy perspective at least.
 

Foxbat

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Stars are big because they use gravitational confinement to initiate thermonuclear fusion. And you need a lot of mass. Thankfully mass likes to accumulate into big blobs. But as we've seen we can use magnetic fields to almost get there. (I think it is controlling the plasma that is really awkward and has been the issue that has been holding up commercial use.)
I've read some conflicting information recently. One says that there are now proven to be three forces (the weak nuclear force is actually part of the electromagnetic force). Another still claims there are four. Either way, the fact that we can use magnetism as a kind of surrogate for gravity makes me wonder if the electromagnetic and gravity forces are more closely linked than we believe (just rambling).
 

Venusian Broon

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Depends on your energy levels. ;)

Today, the weak nuclear force and EM force are clearly different. But it is theorised that they are actually the same force, just different aspects of it. At extremely high energies (only achieved in this universe just moments after the big bang) they would operate as the same force.

I think it's part of the Standard model now. Clearly we can't attain those temperatures, but I think we've experimentally discovered all the correct 'bits' that should make it work.

From dim and distant memory, there was a push to 'unify' all forces - i.e. at very high temperatures EM/weak/strong were all one force. But I don't think that's gone well. You'll also note that this ignores gravity as part of the unification. But this is because the EM, weak and strong forces were described with Quantum mechanics, and we don't have a theory of quantum gravity. Still need that. But I suppose a 'Grand, Grand' unification theory should be trying to merge all forces into one at extremely high energies. So on that level yes, they would be linked.

So EM forces operate on charges, Gravity on the interaction of masses and spacetime. In some ways they are pretty similar - they exhibit inverse square law force interactions. But they are currently on opposite sides of the quantum/relativistic chasm that makes gravity special ;).

However...I did remember an interesting theoretical exploration, in which, someone extended the number of dimensions used in General relativity from 4 to 5. And when they did that, they found something akin to the electromagnetic force arising from it. But this is just a recollection from a John Gribben book in the 1980s and I don't see anyone from the GR side of things taking up this avenue, so I guess it was a dead end.
 

Foxbat

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So EM forces operate on charges, Gravity on the interaction of masses and spacetime. In some ways they are pretty similar - they exhibit inverse square law force interactions. But they are currently on opposite sides of the quantum/relativistic chasm that makes gravity special ;).
I probably asking that question because I've always wondered about the phenomenon of brehmsstralung - specifically how an electron being influenced by a densely populated nucleus is similar to how a spacecraft (or other small body) can be subjected to a similar effect by entering the gravitational influence of a large stellar object. Maybe I'm really just a conspiracy theorist at heart:D
 

Venusian Broon

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I probably asking that question because I've always wondered about the phenomenon of brehmsstralung - specifically how an electron being influenced by a densely populated nucleus is similar to how a spacecraft (or other small body) can be subjected to a similar effect by entering the gravitational influence of a large stellar object. Maybe I'm really just a conspiracy theorist at heart:D
Well, physics is really a bunch of independent constants and a number of (not many) principles that are liberally re-used for all sorts of modelled situations. The principles of physics used in both cases are broadly identical, both involve a masses or charges being slowed in fields, and then the conservation of energy. The electron case is mainly due to its charge, so that the result involved, must be (to my eyes) EM fields.

I'm being a bit slow today ;) :). What's the corresponding result for a spacecraft? IR heating?
 
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