## Centimetre scale models could compute Casimir forces

The Casimir force is notoriously difficult to measure. So tricky is it, that the first accurate measurements weren’t made until 1997 and even today only a handful of labs around the world of capable of taking its measure.

Of course there are various ways of modelling what goes on theoretically but even the most powerful simulations these struggle to cope with simple shapes let alone complex geometries. Consequently, our knowledge of the Casimir  force and how to exploit it is poor.

Now John Joannopoulos and pals at MIT are suggesting a rather entertaining third way: to calculate Casimir forces using scale models that work like analogue computers.

What the team has noticed is a mathematical analogy between the Casimir force acting on microscopic bodies in a vacuum and the electromagnetic behaviour of macroscopic bodies floating in a conducting fluid.

So imagine you want to know what Casimir forces will act on a particular geometry. The idea is to build a centimetre scale metal model of this set up and place it in a conducting liquid such as saline. Then bombard it with microwaves and see what happens.

The result should give an accurate representation of the Casimir forces that would act on the microscopic scale.

The group explains:

Such a centimeter-scale model is not a Casimir “simulator,” in that one is not measuring forces, but rather a quantity that is mathematical related to the micron-scale Casimir force. In this sense, it is a kind of analog computer.

There’s no reason why those kinds of tests can’t be done now.  And that should give researchers a way of testing machines designed to reliably exploit the Casimir force for the first time.

Ref: arxiv.org/abs/0903.0599: Ingredients of a Casimir Analog Computer

### 4 Responses to “Centimetre scale models could compute Casimir forces”

1. Bryan says:

Note really an accurate ‘representation,’ right? It’s rather a closely related analogy. These kind of analogies are very interesting, but in the end, they’re still just analogies. It’s not clear to me what is really learned by studying such things, as the analogy inevitably break down when you get down to the details…

Still, it’s an interesting result nevertheless!

2. ZEPHIR says:

The only problem is, Casimir force is manifestation of shielding force (LeSage gravity model) in five to six hidden dimensions, as the distance dependence of Casimir force constant illustrates.

So I don’t understand, what the water surface model is supposed to illustrate.

3. Igor Bukanov says:

> what the water surface model is supposed to illustrate.

As the article has pointed out, this is not a model but rather an analogue computer.

We cannot solve explicitly the equations for models of Casimir force but, since the equations as the same as for bodies floating in a conducting fluid, we can find the answers for particular set of parameters by simply measuring the behavior of floating things.

4. Zephir says:

I’m just saying, real massive body behaves like dense cluster of another particle clusters with respect to field of virtual photons, so that solid sphere is very simplified model of reality here.