the Casimir effect


Not sure if I should be ashamed of this or not, but the Casimir effect was mentioned on Lost. I’m a fan of the show, but that’s not the point. I googled it and the Wikipedia sounds like technical gibberish. Please ELI5.

In: Physics

> the Wikipedia sounds like technical gibberish.

That is often the case with quantum physics, but luckily it can be simplified greatly. The big difference between quantum physics and classical physics is the idea that the behavior of the universe can be described in “quanta” (plural of “quantum”), the minimum amount of a physical entity involved in an interaction. While classical physics would say that I could push on a box, then push on the box half as hard, then keep cutting that push’s strength in half forever, quantum physics would say that there is some minimum amount of push that could ever take place. That smallest amount would be a quantum, an indivisible unit of interaction.

One of the fundamental properties of the universe is the idea of an electromagnetic field that extends across all of reality. This field is what carries disturbances called electromagnetic waves (light, radio waves, magnetism, etc.), and the force carrier for this field is called a “photon”.

It is also theorized that this electromagnetic field has a net positive amount of energy even in a complete vacuum. This “vacuum energy” is the result of oscillations of the electromagnetic field that average out to nothing on the large scale (cancelling each other out) but are always fluctuating.

What the Casimir effect demonstrates is that if you take two uncharged conductive plates and place them very close together you can create a space where electromagnetic waves of too great a size cannot fit due to the limitations in the quanta of the electromagnetic field. Only photons which have a wavelength that will fit an even number of times into the gap should form part of the vacuum energy, and so the vacuum energy between the plates should be less than that of the ambient vacuum resulting in an apparent attractive force between the plates (really a compressive force from outside vacuum energy).