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Wow, this part blew my mind: > What most intrigued physicists about graphene was how the carbon flatland transformed electrons: Nothing could slow them down. E

Wow, this part blew my mind: > What most intrigued physicists about graphene was how the carbon flatland transformed electrons: Nothing could slow them down. Electrons often get tripped up by the lattice of atoms through which they move, acting heavier than their textbook mass (an insulator’s immobile electrons act as if they have infinite mass). Graphene’s flat lattice, however, let electrons whiz around at a 1,000,000 meters per second — only a few hundred times slower than the speed of light. At that constant, blistering speed, the electrons flew as if they had no mass at all, blessing graphene with extreme (though not super) conductivity. I never thought electron drift velocity could be 1E6 m/s. That's wild. (For comparison, in copper it's closer to 1E-3 m/s.) Related: https://physics.stackexchange.com/q/709168 https://physics.stackexchange.com/q/709168

jonsen 4y ago
Did you ever consider what happens inside a CRT? "In the cathode ray tube, electrons are ejected from the cathode and accelerated through a voltage, gaining some 600 km/s for every volt they are accelerated through.", from: https://www2.physics.ox.ac.uk/accelerate/resources/demonstrations/cathode-ray-tube https://www2.physics.ox.ac.uk/accelerate/resources/demonstra...
- dataflow 4y ago
  A CRT is an approximate vacuum though, right? Quite a world of a difference from drifting through a material at that speed.
  - jonsen 4y ago
    Material is mostly vacuum: "The diameter of the nucleus is in the range of 1.70 fm (1.70×10−15 m ...", from: https://en.m.wikipedia.org/wiki/Atomic_nucleus https://en.m.wikipedia.org/wiki/Atomic_nucleus
    - deleted 4y ago
      [deleted]
    - atoav 4y ago
      Depends for whom. If you punch your fist into a brick wall, neither your fist nor the brick wall will experience the other as mostly vacuum.
      - pmontra 4y ago
        A wall of electrons against anther wall of electrons, same charge, no luck moving through with only our muscles' strength. But if suddenly at least one of those walls can move through electrons it finds mostly vacuum in front of itself. I think this is what happens in that material.
        ctrlmeta 4y ago
        The visual we draw in our mind that the atom is mostly vacuum inside is due to taking our intuition about classical physical world and misapplying it into the world inside an atom where classical physics intuition is not relevant. In quantum physics, an atom is not mostly vacuum. It is filled with wavefunctions of the electrons.
        altruios 4y ago
        people say this casually... and fail to define what a wave-function is physically. It sounds like a non-sense answer. if there is matter there, in the form of a 'wave function', what is the matter of a 'wave function' (other than just the electron zipping about)? no: a wave function is a mathematical construct we use to predict where an electron might appear... (well, not exactly the wave function, but we get the probability of an electron's appearance by squaring the wave function). A wave function (probably), doesn't 'physically' exist. it's just a useful model to predict probabilities... waves exist only in a medium of expressive material - if that material is a single electron, there isn't magically more material there once we use a wave function to predict it's location - it's still only one electron - it's position predicted by the square of the wave function - but that doesn't mean the wave function is a physical entity. And it's not like the electron is 'going faster than light' and 'blurring frames in reality'... it's just the electron there - the squaring wavefunction is just a way to predict it's location: just because it (seems to) works doesn't mean it physically exists. but if it DOES exist physically (in a concrete way) - I would love an explanation or link to that proof - as that would be news to me. fundamentally this might just be a semantics issue on the word physical
howmayiannoyyou 4y ago
Energy weapons. These will greatly benefit from this presuming the energy storage/supply side can be addressed.
jpmattia 4y ago
> I never thought electron drift velocity could be 1E6 m/s. That's wild. GaAs, InP, and InAs have measured max electron velocities in the ballpark of 300,000 m/s, which is ~ 1/1000 of c. So they're listing graphene at around 3x of pretty standard III-V materials. (It's a nice improvement in speed, but building good electronic devices involves much more than electron velocity.)

jonsen 4y ago

Did you ever consider what happens inside a CRT? "In the cathode ray tube, electrons are ejected from the cathode and accelerated through a voltage, gaining some 600 km/s for every volt they are accelerated through.", from: https://www2.physics.ox.ac.uk/accelerate/resources/demonstrations/cathode-ray-tube https://www2.physics.ox.ac.uk/accelerate/resources/demonstra...

dataflow 4y ago
A CRT is an approximate vacuum though, right? Quite a world of a difference from drifting through a material at that speed.
- jonsen 4y ago
  Material is mostly vacuum: "The diameter of the nucleus is in the range of 1.70 fm (1.70×10−15 m ...", from: https://en.m.wikipedia.org/wiki/Atomic_nucleus https://en.m.wikipedia.org/wiki/Atomic_nucleus
  - deleted 4y ago
    [deleted]
  - atoav 4y ago
    Depends for whom. If you punch your fist into a brick wall, neither your fist nor the brick wall will experience the other as mostly vacuum.
    - pmontra 4y ago
      A wall of electrons against anther wall of electrons, same charge, no luck moving through with only our muscles' strength. But if suddenly at least one of those walls can move through electrons it finds mostly vacuum in front of itself. I think this is what happens in that material.
      - ctrlmeta 4y ago
        The visual we draw in our mind that the atom is mostly vacuum inside is due to taking our intuition about classical physical world and misapplying it into the world inside an atom where classical physics intuition is not relevant. In quantum physics, an atom is not mostly vacuum. It is filled with wavefunctions of the electrons.
        altruios 4y ago
        people say this casually... and fail to define what a wave-function is physically. It sounds like a non-sense answer. if there is matter there, in the form of a 'wave function', what is the matter of a 'wave function' (other than just the electron zipping about)? no: a wave function is a mathematical construct we use to predict where an electron might appear... (well, not exactly the wave function, but we get the probability of an electron's appearance by squaring the wave function). A wave function (probably), doesn't 'physically' exist. it's just a useful model to predict probabilities... waves exist only in a medium of expressive material - if that material is a single electron, there isn't magically more material there once we use a wave function to predict it's location - it's still only one electron - it's position predicted by the square of the wave function - but that doesn't mean the wave function is a physical entity. And it's not like the electron is 'going faster than light' and 'blurring frames in reality'... it's just the electron there - the squaring wavefunction is just a way to predict it's location: just because it (seems to) works doesn't mean it physically exists. but if it DOES exist physically (in a concrete way) - I would love an explanation or link to that proof - as that would be news to me. fundamentally this might just be a semantics issue on the word physical

howmayiannoyyou 4y ago

Energy weapons. These will greatly benefit from this presuming the energy storage/supply side can be addressed.

jpmattia 4y ago

> I never thought electron drift velocity could be 1E6 m/s. That's wild. GaAs, InP, and InAs have measured max electron velocities in the ballpark of 300,000 m/s, which is ~ 1/1000 of c. So they're listing graphene at around 3x of pretty standard III-V materials. (It's a nice improvement in speed, but building good electronic devices involves much more than electron velocity.)