Aethari

My one friend and I got into a little debate over whether anything is truly 'random'. Before I say anything else, I should explain what I mean by random-- something that, literally, occurs for no reason, an event which had no causal influence acting to intiate it.

We got into talking about quantum theory, and the probabalistic interpretation of things, that given a particle set up identically multiple times, it would end up in different places for no apparant reason. Hence, probability is assigned to events, and in the large-scale movements of matter things appear to be deterministic in the classical Newtonian sense.

My question is this: are physicists saying that elementary particle movement is truly random, or that they simply do not know why the particles behave as they do? I found it deeply unscientific to say that particle movement is random-- that is, they move as they do for no distinct reason. I hope I'm making sense. I argued that scientists aren't saying that particles move randomly without reason, but rather that they move as they do for reasons beyond our scope or ability to analyze. Isn't labelling the movement as 'random' simply giving up? Who is right here?

Thanks for any help.

~Aethari

Oxymoron

Some aspects of a particle's states are truly random. "Movement" is too vague to be considered random. However, radioactive decay is a truly random quantum process - you can never say when the decay of a particular atom will take place in principle as well as empirically.

Aethari

I don't want to annoy, but that doesn't seem to satisfy me =p. Do we know that the decay is "truly random", or do we just not know why it happens, and are labelling it random out of ignorance? This is what I don't understand-- how can we ever say that something is random, and not simply the result of processes we have yet to discover?

~Aethari

[ November 14, 2002: Message edited by: Aethari ]</p>

Butters

I allways find it strange that so many people (theists) are afraid of a random universe. For some reason it is comforting to know that every thing is random, rather than trying to figure out what is causing what. God works in mysterious ways is really unsatisfiying.

Hawkingfan

In regards to Heisenberg's uncertainty principle, he discovered the following in 1925:
--You cannot precisely locate the position of a subatomic particle, unless you are willing to be very sure about it's velocity.
--You cannot precisely determine the particle's velocity, unless you're willing to be very unsure about it's precise location.

It's not that we can't measure both the position and velocity, but that a particle does not have BOTH a precise location and a precise momentum at THE SAME TIME. At any point in time, a particle such as an electron cannot itself know both where it is and where it is going. It's a fact of nature. Like trying to physically look at both sides of a coin at the same time. It can't be done.

Oxymoron

It's not annoying! (Not yet, anyway ). Yes, there are indeed ways to determine if certain quantum processes are random, or are controlled by some "hidden" regularity. They are pretty deep, and very mathematical, and I'd be lying if I said I understood them enough to defend them. Anyway, long story short, it turns out that experiments have verified that there are (and CAN BE) no hidden variables regulating random processes.

What remains for you is to either accept this at face value, or to read - a lot! - about this till you can understand the arguments. Try a Google search for "Bell Inequality", but if you are new to Quantum Physics you might need to do a lot of background reading.

Aethari

Thank-you Hawkingfan, but that I'm still left wondering. Are we saying that things like quantum decay are not the result of a specific causal sequence, or just that we do not know now or can never know that sequence? It seems presumptious to declare something as random...wouldn't we have to know everything in order to conclude that something is caused by nothing?

~Aethari

EDIT: Oh, crossposted and missed Oxy's response.

[ November 14, 2002: Message edited by: Aethari ]</p>

Aethari

Oxy-

Ok, I'll take your word on it. That seems deeply unsettling though-- things happening for absolutely no reason. That will take some thought on my part, because I find it very disturbing philosophically that something could happen without a causal sequence leading into it. I don't know if this is a conceptual difficulty or what, but I can't understand how anything could happen without something, anything, causing it to happen. True randomness seems nonsensical, at least to me. Hum.

*Marches off to think deep thoughts about physics and philosophy*

~Aethari

Oxymoron

Quote from Niels Bohr: "If Quantum Mechanics hasn't shocked you, then you haven't understood it yet".

At a deeper level, there's no a priori reason for the workings of the universe to be palatable - or even understandable - to us. We just have to deal with it as we find it.

Aethari

Wow! Isn't that something. I searched for 'Bell Inequality' as you suggested, and found this interesting site:

<a href="http://www.telp.com/philosophy/qw3.htm" target="_blank">Quantum Weirdness</a>

This is perhaps why I found the concept so weird-- I have a deep attachment to metaphysical realism, and I realized full well the problems that true randomness would present

So, along those lines-- is the author's thought, and my own accurate when we assess the Copenhagen Interpretation of Q.M. to be throughly undermining of metaphysical realism? Thoughts on that?

~Aethari