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Virtually impossible on the macroscopic scale.

 
 
SMS
04:22 / 31.01.04
According to quantum mechanics, a lot of things are technically possible on the macro scale, but so improbable that it would take millions of times the age of the universe for their occurence. For instance, we may as well call it impossible that all the air molecules in this room jump over to one corner. One thing I have always wondered about, however, is how many of these virtually impossible events are possible. And most specifically, whether that number could be large enough that the virtual impossibilities in general actually become likely. One problem with this question is that there doesn't seem to be any way of testing it. One cannot set up a lab looking for things that are specified as nothing more than virtually impossible. In most labs, if that were to occur, the best explanation for it would be an equipment malfunction. However, I am curious about whether anyone knows if the theory pedicts this kind of thing will happen.
 
 
Wombat
21:38 / 10.02.04
As far as I`m aware you have it pretty much spot on.
I`m gonna give a further explanation just because you deserve a reply.

The easiest way to think of this kind of thing is to use a phase space. Where all the possibilities are represented in the volume.

For example. You have N particles in a 10*10*10 room. They don`t interact. They move at a random speed and interact randomly with the walls (otherwise it is less probable they are in the corners...imagine throwing a ball into a tri-hedral and getting it perfectly in the corner).

So for a 1 volume there is a 1 in a 1000 chance of the particle being in any 1 cubed volume. For two particles it`s 1 in (1000*1000). And so on.

Throw in temperature (where the energy of a particle is statistically 3/2 kT) and wave functions (from Quantum Mech.) you can predict the probability of any number of particles being in a volume of a room. (A subject called statistical mechanics)...which post-dicts the laws of thermodynamics.

I`m sure someone somewhere has sat down and calculated the stats for air rushing to one corner of the room. I`ve never seen it though.(the calculation...or the air rushing). It`s not gonna happen in a very long time though.
 
 
grant
13:28 / 11.02.04
Also, from the perspective of a quantum particle, something that happens to a whole molecule or even a cluster of molecules is pretty macroscopic. So air molecules could be disappearing and reappearing all the time around you, and you'd never know it.
 
  
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