h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

If the cat is constantly interacting with (the rest of the entire universe) by gravity / electromagnetism, etc (exchanging gravitons, virtual photons, whatever) surely the cat is in a continuous process of observation, anyway...???

One could come up with a more efficacious box that is proof against these phenomena.

That's why it's a thought experiment, there is no realistic way to put the cat in a box that seoerates if from all observers.

You can however do it with small particles, as gravity and other forces have a much smaller effect on them.

Is 'Observation by environment' believed?

What is the answer to the objection that the universe has no environment, so its wavefunction shouldn't collapse?

Again, that's one of the problems: "Does the fact the universe is watching make any difference to the cat?"

Presumably that's what keeps you from banging into coffee tables from anotehr universe while you walk about the house in the dark at night, searching for the light switch.

The thought experiment does not itself require a cat. Suppose instead that you place a firecracker in a thick soundproof box, with a fuse connected to some sort of random number generator that would have a 50/50 chance of lighting the fuse. That way, the firecracker is both exploded and not exploded until the box is open, and there's no issue of a consious observer.

Good point.

However, one of the tennants is that the box seperates the firecracker from the rest of the universe, so that nothing outside the box can influence the items in the box. At the scale of cat or firecracker, this is effectively impossible.

I't isn't that it separates the firecracker apart from the rest of the universe, it just sets it out of observation to the rest of the Universe

Well, yes, but there is a thinking amoung some scientists that you need to seperate it from all *possible* forms of observation, effectively this translates as "cut off from the universe", but I can't remember why.

In any case, it's not like this is a practical experiment. Anyway, it could be argued that the operation of whatever device is governed by the state of the photon is a measurement in and of itself.

Myself I prefer the "Many Worlds" take on the issue, because it makes more sense that instead of two superimposed cats, there are merely two (among an infinite number of) superimposed universes. Furthermore, when you combine it to chaos theory, one can only wonder what crazy things exist in these other universes.

In any case, this discussion is by far more interesting than the impression one often is given of quantam mechanics by all of the strags who shy away from it.

Yes, the many worlds theory is a method of quantum computing.

If you could tap into it, you could break a combination lock with one code, never having to try any of the wrong combinations that set off the alarm.

The device would "unfold" many universes, try every possible combination in them, and tell you which one worked.

It has been used as a plot device in many sci-fi stories.