1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Can superconductors conduct electricity at absolute zero?

  1. Oct 9, 2015 #1
    I've just learnt that the conductivity of super conductors increases with decrease in temperature and it becomes infinite at absolute zero. But I thought that all motion ceases at absolute zero. So how can current flow in such conditions? And how can its resistance become zero as some resistance is also offered by the positive ions or maybe the positive charge?
  2. jcsd
  3. Oct 9, 2015 #2
    In superconducting materials electrons form pairs known as cooper pairs.When two electrons move towards a positive ion they tend to reach an equilibrium state and become electrically bonded.These cooper pairs are responsible of electrical conductivity in a superconductor.The movement of these cooper pairs lead to photon emission making them to propagate easily through the lattice.Refer BCS theory for more info. figure8.jpg
  4. Oct 9, 2015 #3
    But can you clear the point that how can current flow at absolute zero when it is theoretically said that all motion ceases at absolute zero.
  5. Oct 10, 2015 #4
    Yes at absolute zero the current flow. From my point of view the atoms have zero kinetic energy but electrons continue to move.
  6. Oct 10, 2015 #5
    Ok. Thanks anyways.
  7. Oct 10, 2015 #6


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    Please note that for superconductors, the DC conductivity goes to infinity at and below Tc, the superconducting critical temperature, and not just at absolute zero. This means that for some superconducting compound, this critical temperature can be as high at 130 K.

  8. Oct 10, 2015 #7
    Its very hard to freeze a electron.Since electrons are leptons they do not react by mass,that loss of kinetic energy of a substance doesnt stop all electrons.Its because the no of electrons is far greater than the number of positive ions.Hence there is always electromagnetic fluxuations in a substance.So electrons do move due to flux variations.This makes it very difficult to reach absolute temperature.
  9. Oct 10, 2015 #8


    User Avatar
    Staff Emeritus
    Science Advisor

    I don't think this is correct. Absolute zero is impossible to reach because it is impossible to exactly cancel out all the different vibrations, rotations, and translations that the particles composing a material are undergoing. In addition, the existence of a ground state prevents electrons from losing all of their momentum anyways.

    I don't know what 'react by mass' means.
  10. Oct 11, 2015 #9
    I said that because electrons has less mass compared to a positive ion,they react electromagnetically rather than gravitationally(ie.by mass).
    I may be wrong but i still dont see any plausible explanation to her question.
    Thanks for correcting me anyways.
  11. Oct 11, 2015 #10


    User Avatar
    Staff Emeritus
    Science Advisor

    Well, no, that's not correct either. We can effectively ignore gravitation here, as it has little to nothing to do with why absolute zero is impossible to reach or why superconductors behave the way they do.

    That's a misconception. Motion does not cease at absolute zero. Instead, the particles making up the material would be in their ground state, which is a minimum energy level. They literally cannot lose any more energy and stop moving.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook