Suppose we have a plain coherent light wave impinging on a double-slit. From electromagnetic theory we can calculate an interference pattern on a detector screen behind the double slit screen.

But from quantum mechanics we know that if we allow only one photon at a time to pass through the slits, the location of the photon detection on the detector screen could be anywhere in the interference pattern except at its nulls.. It is only after numerous photons are so detected that the interference pattern emerges.

So the interference pattern is the probability of where a single photon might be detected.

Now let's compare this to the process of throwing dice. Can I get your agreement that what number comes up for a particular throw is random with probability of 1/6 for each of the numbers?

If so then the dice experiment and the double-slit experiment behaves exactly the same. The randomness is evident for a few trials. But if we get enough trials, each of the dice numbers comes up roughly the same number of times. We can even calculate the deviation away from the norm.

So it is in this sense that physical processes are random. If we knew all the forces acting on the dice all the time, we could calculate what number comes up each time. But that does not mean that the process of throwing dice is not random. If you define randomness differently, then you are not using convention.

• Excuse me for being picky - aurino - August 15, 2001 - 16:12 UTC
  • By your definition there is ni randomness - yanniru - August 15, 2001 - 16:54 UTC
    • So randomness really means "we have no clue"? - aurino - August 15, 2001 - 18:11 UTC
      • On this basis quantum mechanics is theistic - yanniru - August 15, 2001 - 20:18 UTC
        • Do you think Steven Weinberg would agree? (nt) - harvey1 - August 15, 2001 - 21:18 UTC
        • Not that fast! - aurino - August 15, 2001 - 21:20 UTC
          • Your definitions, not mine - yanniru - August 15, 2001 - 22:58 UTC
            • That's not what I said - aurino - August 16, 2001 - 14:07 UTC