# B Is it possible to create macroscopic Casimir effect?

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1. Aug 1, 2016

### Bawelna

Hello.
I read a lot about Casimir Effect. It creates attractive (or repulsive)force between two metal, parallel, electrically neutral, conducting plates. It causes that between plates, it is less electromagnetic field fluctuation wavelength than outside (vacuum). Logic tells me that if vacuum energy is zero-point energy that energy between casimir plates must be NEGATIVE! I also read that casimir effect is measurable if the gap between plates is less than 7-5 nanometers. Is it possible to operate casimir effect on macroscopic scale, say a few centimeters, meter?

2. Aug 1, 2016

### Staff: Mentor

The energy scale is arbitrary if we leave out gravity. It is convenient to set the energy density of the vacuum to zero, but it is not necessary. If you do it, you get negative energy densities between the plates.
You have it at any scale, but for a distance of more than a few nanometers it is completely negligible.

3. Aug 1, 2016

### Bawelna

Is it possible that the Casimir force on a macroscopic scale was the same as in the microscopic scale? Maybe by controlling electromagnetic field?

4. Aug 1, 2016

### Staff: Mentor

You try to make categories that do not exist. For parallel plates at distance d and area A, the force is$$F=\frac{\pi^2 \hbar c}{240} \frac{A}{d^4}$$
Plug in A = 1 mm2 and d = 5 nm and you get 2 N - a measurable force. Plug in A = 1 m2 and d = 10 cm, and you get 1.3*10-23 N - completely negligible. It is exactly the same effect described by the same formula, but on larger scales it is negligible.

Last edited: Aug 1, 2016
5. Aug 1, 2016

### gildomar

Hey @mfb, shouldn't the distance be to the 4th power, not the area?

6. Aug 1, 2016

### Staff: Mentor

Oops, typo. LaTeX tried to put the whole fraction to the 4th power.

7. Aug 1, 2016