strubenuff

Bill said I myself am a believer in a pre-determined reality. However, many have tried to persuade me by means of quantum uncertainty; claiming that, even with an infinite knowledge of all factors, it is still impossible to make completely accurate predictions at the quantum level. Is it still possible that "randomness" on smaller level can produce a coherent and determined existence on "macro" levels?

I didn't see this point brought up in the other two threads (free will vs determinism), so I apologize if this is redundant.

K

I would assert that if the randomness inherent in quantum mechanics is truly an attribute of the physical world (which it appears to be), then the state of the universe can not be strictly deterministic even on the macroscopic level. This can be seen when we do experiments where we force the breakdown of quantum coherency through observation. The result would be that the randomness would then operate on the macroscopic world through the subsequent actions of the observer.

Despite the lack of absolute determinism, I still think that the brain behaves in a deterministic manner on the macroscopic level. There is no real free will because the output of a brain will be determined by its structure and the sum of all of its previous inputs. It's just that those inputs aren't strictly determined if the randomness of quantum mechanics prove true.

tronvillain

Well, the effects of quantum mechanics are real and they do produce a deterministic world, regardless of whether they involve actual randomness or merely pseudo-randomness. All that would be affected one way or the other would be whether determinism is strict or probablistic, but at our scale the two are relatively indistinguishable - quantum effects simply average out to give us the world we see around us regardless of whether they are truly random or not.

K

tronvillian:

I think I understand what you are saying, but I'm not sure I agree. Quantum mechanics implies non-causality at the quantum level. The output can not be determined solely by the initial conditions. The same experiment can give two different results even with the EXACT same initial conditions. The definition of determinism that I'm using is:

Belief that, since each momentary state of the world entails all of its future states, it must be possible (in principle) to offer a causal explanation for everything that happens.

This is clearly contrary to the underlying features of quantum mechanics. I've never heard of probablistic determinism. Please provide a definition.

I understand that we don't generally see quantum effects at the macroscopic level. However, I was pointing out that we can do experiments that produce a result based on breaking the coherency of a quantum superposition. When we see the result of the experiment, the quantum uncertainty has now become a macroscopic part of our world.

If the non-causal foundation of quantum mechanics is an accurate reflection of the real world (and so far every indication says that it is), then the universe really can't be deterministic.

The brain can still behave in a deterministic macroscopic way, though. A state machine is deterministic for an initial starting state and a sequence of input pattern. But, the system is not deterministic if the inputs to the state machine can be influenced by quntum mechanical indeterminacy.

99Percent

The way I look it at is that at the quantum level states are definitely undetermined (pun intended), but on the human level states looked determinable. This is because at the human level the quantum states for trillions of particles for trillions of instants have already been defined.

The analogy I like to use is that of a casino. On a single bet you might win, but as time and bets are executed, the casino eventually wins. Likewise at the quantum level a particle might be or not be, but in the long run and considering all the other factors the particle is or is not set, even though with fantastic odds the particle cannot be set at all even though it is supposed to be set.

For example it is possible that a can of beer to unmaterialize on my desk and rematerialized instantly in another part of the universe, but given the ammount of particles a can of beer is composed, the odds are so astronomical that it is virtually impossible - yet quantum physics disallows discarding its impossibility absolutely! Likewise breaking a casino with just one penny is virtually impossible, but not absolutely so.

[ August 23, 2002: Message edited by: 99Percent ]</p>