Random particle movement (with pictures!)

  • #1
I'm trying to understand the movement of particles due to quantum mechanics. I made this image. It is a magical receptor box. Every time an H atom strikes a receptor, the letter associated with that receptor shows up as a read out on a computer. For example if a H atom hits the top receptor, it would read out "a". Every time a receptor is hit, another letter is added. You might see "abebdceavaaabedcdea" after a second.

What I want to know is, if you could have two "universes" (this has nothing to do with alternate universes) each with its own receptor box, with the EXACT SAME initial conditions for EVERY variable (same temperature, same exact position of H atoms, etc), and after 10 seconds, you freeze time and look at the computers, will the read outs be the same? Would one say "cebeadcbea" and once say "decbccbbaaaebca"?

Basically, do they move randomly? If they do, does decoherence stop their random movement since they will obviously collide with each other or the walls of the box. [edit] When I say random movement, I do NOT mean normal bouncing around like a bunch of rubber balls in a box. I mean random movement because of whatever quantum forces.

[PLAIN]http://img9.imageshack.us/img9/7637/tankdu.jpg [Broken]
 
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  • #2
ZapperZ
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I don't see how this any different that classical statistical mechanics. What am I missing here?

Zz.
 
  • #3
While it seems similar, I was under the impression from three Physics professors that small particles move in a random, uncaused fashion. Something about particle scattering?
 
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  • #4
Fredrik
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will the read outs be the same? Would one say "cebeadcbea" and once say "decbccbbaaaebca"?
They wouldn't be the same, so the result would be something like what you're suggesting.

It seems that what you're visualizing is an essentially classical view of what's going on. In particular, you're assuming that particles have positions. Since QM doesn't actually say that they do, we shouldn't assume that they do.

These things are discussed in this thread. See post #51 for my conclusion.
 
  • #5
Basically, particles have a mind of their own? That's all I'm trying to find out.
 
  • #6
Fredrik
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QM doesn't tell you what the particles are doing. It just tells you how to calculate the probability of each result like decbccbbaaaebca.
 
  • #7
Okay, so why would you get different combinations of letters each time then?
 
  • #8
Fredrik
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If you want an answer that has something to do with QM, all I can say is "because the probabilities assigned by QM aren't always 0 or 1". I can't tell you why a quantum theory makes better predictions than all classical theories. I don't think anyone can.
 
  • #9
I don't mean why as in "Why?". I'm aware no one knows. I mean, what actually goes on physically, to create the randomness.
 
  • #10
Fredrik
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As I said, QM doesn't tell you that. So what theory do you want me to use to answer it?
 
  • #11
Sorry, I didn't know you meant it like that. Does this apply to particles larger than atoms? The double slit experiment was preformed with carbon fullerenes but I'm not sure if that applies to this.
 
  • #12
Fredrik
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Yes, my answer applies in that case too.
 
  • #13
Last question then. Do the effects of constructive and destructive interference remove any of this randomness?
 
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  • #14
Fredrik
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It can change the probabilities to either 0 or 1 in some very specific situations, but we would still have to use QM to find that result, so those situations aren't fundamentally different.
 
  • #15
Would coming in contact with each other very often as in particles in a gas or liquid be one of those cases?
 

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