# Casimir effect limit

1. Oct 26, 2015

### _PJ_

I was thinking recently about the Casimir Effect and at what distance does the effect become negligible?

Is there any relevance on the surface area (or difference in areas) between the plates (I personally held the opposite, that any point can be considered to have equivalent pressure as any other approximated over time).

Naturally, this distance would entail the point at which there is a balance between the internal (i.e. between plates) and external pressures is when the plates are no longer 'pushed' together as result, but at what length does this occur? Presumably there will always be a very slight imbalance one way or the other due to continuous fluctuation, although at the given length there will be an overall equilibrium so as there is no net change in the plate positions over time.

----

ALMOST related, and perhaps worthy of its own thread, but it is relevant enough to be here I felt, is there any evidence or possibility for "capillary action" or suitable equivalent analogue with Casimir effect type small spaces and quantum foam 'fluidity'?

2. Oct 26, 2015

### Staff: Mentor

At what distance does the gravitational attraction of Earth become negligible? There is no sharp border, it just gets weaker and weaker.

For parallel plates of ideal conductivity, it is $\displaystyle {F_c \over A} = -\frac {\hbar c \pi^2} {240 a^4}$ with the distance a.

3. Oct 27, 2015

### Khashishi

Negligible only has meaning with respect to some kind of comparison.

4. Dec 21, 2015

### _PJ_

Thank you so much!

As is usually the case with such questions, with hindsight it seems remarkably obvious!

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook