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Thread: Nothing can travel faster than light, but nothing slower?

  1. #1 Nothing can travel faster than light, but nothing slower? 
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    Just wondering considering that the speed of light is an oft discussed topic in physics that it's not looked at in the way of how slowly an object can move?

    I think it obvious btw that I have no education whatsoever in physics, so it's probabaly a really dumb question

    So the point is, there must be a minimum distance an object must move or else it doesn't exist?

    In any case, this is too much for my puny brain, just looking for views from smart people :-D


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  3. #2  
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    Ordinary objects (mass > 0) have only relative speeds (although always < speed of light). An object can have 0 speed relative to another object, but absolute speed of 0 is meaningless.


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    In macroscopic physics, zero velocity is of course possible. An object does not simply seize to exist just because it does not move.

    But there are really strange configurations on quantum levels like the so called Fermi gas. On subatomic levels, the Pauli principle postulates that two fermions cannot co-exist having the identical energetic configuration. Therefore, if you have a group of fermions (e.g. electrons), they all have to have different velocities. So, if there are already electrons having zero velocity, then any other electron added to that ensemble of particles cannot fall below a certain velocity. So, in this case, such a configuration of fermions determines a characteristic lower limit of velocity for any additional fermion.

    Such entities do exist, like a White Dwarf. Their cooling is inefficient, because temperature is the macroscopic quantity that describes the velocity distribution of e.g. electrons in a plasma. Since a White Dwarf is a very special thing, the fastest electrons of the stellar plasma cannot reduce speed, because the energy level that represents this speed is already occupied by another electron. However, the plasma also contains bosons (e.g. helium nuclei) to which the Pauli principle does not apply and that can do the cooling.
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