Does the universe has a capacitance?

  • Context: Graduate 
  • Thread starter Thread starter shpongle
  • Start date Start date
  • Tags Tags
    Capacitance Universe
Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
4 replies · 3K views
shpongle
Does the universe has a capacitance?
 
Physics news on Phys.org
The units of permittivity of space can be written as farads/meter.
 
shpongle said:
The units of permittivity of space can be written as farads/meter.

so, do we multiply [itex]\epsilon_0[/itex] by the number of meters across the known universe (which might be something like [itex]c[/itex] times 13.7 billion years)? is the capacitance of the universe growing as the universe expands?
 
rbj said:
so, do we multiply [itex]\epsilon_0[/itex] by the number of meters across the known universe (which might be something like [itex]c[/itex] times 13.7 billion years)? is the capacitance of the universe growing as the universe expands?

That is what I meant.

I don't even know if it is a valid question but it occurred to me a few hours ago while I was trying to understand permittivity, which appears as a proportionality constant in the Gauss' Law.
 
No, because it does not have an electrically contiguous surface.

The capacitance of a thing defines its electrical potential given a state of charge on it. As the charge cannot distribute itself on any 'universal' structure (as no such structure exists), so there can be no 'universal' capacitance.