Originally posted by: Blouge
>Yes, it is random.
That's not a scientific statement. It's not possible to measure a process and establish that its random. You can only establish that the process obeys a given statistical model. QM, for example, is a deterministic theory that yields precise statistical distributions, which are backed up by experiment. You might go further and claim there's randomness yielding the distribution, but that's only for reasons of convenience. For example, Einstein used randomness in his model of Brownian motion, yet he remained a staunch determinist. To jump to conclusions and embrace QM and randomness as the foundation of the universe is foolhardy, in light of QM's flaws (intractable GR incompatibility) and our primitive state of knowledge. There's no laboratory equipment to distinguish "randomness" from pseudorandomness, human conciousness, God's will, each particle has its own free will (heard this one recently), Everett's many worlds, and who knows what else.Perhaps we'll find nonlocal hidden variables, a possibility which could actually be scientifically verified. For now, I suggest using Occam's razor and admitting that the answer is just our own plain ignorance.
Techically you are almost right, but you are again confusing philosophy with science.
The problem with your argument is that it makes it impossible to "know" anything.
QM does, as you say, make it possible to calculate the distribution function of a certain process. Now, if I then perform a measurement and the result does indeed agree with the QM prediction I would say that QM was correct, the process is random (remember that the "randomness"-property was used when I calculated the disitribution.
Now, of course I can't be sure of this in the "philosophical" sense, since it enirely possible that I will get a result that
does not agree with QM if I repeat the same experiment the following day
but that is true for all theories. It is impossible to PROVE a theory, you can only prove it wrong.
Hence, from a "philopsophical" point of view we can never know anything for sure but that does not stop us from using QM or any other good theories in e.g. engineering and when we do that we generally speak about results being correct or not: which is why I gave the answer "yes, it is random".
While saying "we don't know anything" might be interesting from a philosophical standpoint it doesn't really help if you want to e.g. calculate how much concrete you need to build a bridge ("According to the theory I need 10 tons, but since we can't be sure the theory is correct I will use 3 instead")
Also, note that I said "almost" in my first sentence. There are ways to test QM (and local realism in particular) which DO NOT direcly rely on calculating distributions.
In the latest issue of Nature (vol 445, pp. 723) there is an interesting article by Gregor Weihs where he is commenting on some recent experiment using neutron diffraction to test "quantum realism" (Hasegawa et al, Phys. Rev. Lett vol 97, 230401). The experiment is relevant here since it directly test for local variables (in this case non-contextual variables, which are more general than "ordinary" hidden variables) and specifically "randomness" (using Kochen-Specker inequalities).
Not surprissingly, the QM predictions are correct.
I can reallly recommend Weihs article for those of you who have access to Nature, there is no math involved so it is relatively easy to read.
Hasegawas paper is on the other hand quite techical so unless you have a background in neutron diffraction (I don't) it is not very helpfull.
The conclusion by Weihs based on this (and other earlier experiements) is that the world is "fundamentally random", at least in the scientific sense.