Does the universe has a capacitance?

AI Thread Summary
The discussion centers on whether the universe has capacitance, referencing the permittivity of space expressed in farads per meter. It questions if multiplying the permittivity by the universe's size, estimated at 13.7 billion years of light travel, could yield a capacitance value. However, it is argued that the universe lacks an electrically contiguous surface necessary for defining capacitance. Consequently, without a universal structure for charge distribution, the concept of universal capacitance is deemed invalid. The conversation highlights the complexities of relating physical constants to the universe's expansive nature.
shpongle
Does the universe has a capacitance?
 
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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 \epsilon_0 by the number of meters across the known universe (which might be something like c times 13.7 billion years)? is the capacitance of the universe growing as the universe expands?
 
rbj said:
so, do we multiply \epsilon_0 by the number of meters across the known universe (which might be something like c 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.
 

Thread 'Why measure the speed of light in one direction?'

It may be shown from the equations of electromagnetism, by James Clerk Maxwell in the 1860’s, that the speed of light in the vacuum of free space is related to electric permittivity (ϵ) and magnetic permeability (μ) by the equation: c=1/√( μ ϵ ) . This value is a constant for the vacuum of free space and is independent of the motion of the observer. It was this fact, in part, that led Albert Einstein to Special Relativity.
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