yguy

http://www.iidb.org/vbb/showthread.p...threadid=51776

Originally posted by Doubting Didymus:

You are suggesting that with full knowledge of the forces involved, we could predict atomic motion with complete accuracy.

In fact, I believe that there are events at the quantum level that can not be predicted at all, and appear to occur with total randomness, meaning that we can never predict movements with 100% accuracy, but only speak of them as having a certain probability. Physics isn't my thing, though. Discussion of that point should be taken to science and skepticism, where I would be interested to see the discussion myself.

Here ya go, sport.

I invite interested parties to review the thread above and raise objections to anything I said there. Just to recap, my thesis is that the validity of any scientific theory is suspect to the degree to which it is based on probability, since science is that which is known - which includes knowing when something is NOT known - whereas the reliance on probability tends to be ignorance posing as knowledge, especially as evidenced in a statement like, "Your DNA is governed by random processes." This is just away of saying it's not known how it is governed - along with a tacit admission that it is governed somehow.

NialScorva

Quantum events are completely probabilistic, though as a general rule you only see the expectation value for the probability distribution on a macro scale.

It's tangentally related to your point, but in computer science there's a lot of probabilistic methods being used these days. Many problems are simply impossible to solve deterministically in a reasonable amount of time, but you can get a "good enough" answer if you use a bit of randomness.


Another thing to consider is what "random" means. In the majority of cases, random can be interpretted as meaning "exhibitting a non-deterministic relationship with the system under investigation". Another way to consider it is that "random" is almost exclusively only random in relation to a partiular system. This holds true when discussing random mutation. There may be a theoretically identifiable causality behind a particular point mutation, but the point is that it is random relative to the survival of the organism.

I think you have it backwards, actually. When someone says "process X in system Y is random", it is usually irrelavent whether X is random *outside* of system Y. Your statement is whether X is random outside of Y. It's not a weakness for biology to say "mutation is random within the context of genetics". If you want them to be non-random, you can step out of the system and say that mutations are non-random, since they're caused by radiation, chemicals, transcription errors, etc. That has no bearing on whether they're random within biology.

The reason I mention this is because in quatum physics, not only is the process random within the system, it's provably random outside the system as well. In fact, this randomness is part of what makes solid-state physics (and thus computers and other electronics) work.

Jayjay

Consider these two statements:

"X is governed by random processes"
"X is governed by deterministic processes"

Does one of them imply that we know more about X than the other? What if we extend the description of X as follows:

"X is governed by random processes A, B and C"
"X is governed by deterministic processes D, E and F"

The point of this little word play is that there's really nothing in the word "random" that says we don't know the processes themselves. It just says that the processes in question have a property of randomness, as opposed to determinism, for instance. We may or may not know what the processes are, but the sentence "X is governed by random processes" alone does not give away this piece of information.

Tabula_rasa

Just in case you all didn't have the chance to weed through the entire thread, we have this little gem from yguy on page 2 :

Tabula_rasa

Wounded King

I very much doubt anyone has claimed that your DNA is governed by random processes. If it was then I fail to see how any sort of cellular life could exist. DNA is subject to random mutations, such as those caused by UV light or mutagens, and there are specific probabilities governing a number of problems involved in DNA replication.

Your DNA is mostly goverened by a wide variety of proteins which interact to stabilise and regulate its structure, as well as to replicate it or use it as a template for mRNA. In as much as all interactions between molecules are probabilistic then these interactions are. Bring governed by probability is by no means the same thing as being random however.

There are also specific regions of DNA which are more prone to mutation than others. An admission that something is governed by the laws of probability is just that.

Shadowy Man

We have a theory.

The theory makes predictions about observables.

We make observations.

We compare the observations to the predictions.

If the theoretical predictions agree with the observations we have more reason to believe the theory. If not, then we need a better theory.

We believe the theory is accurate to the extent that the predictions agree with the observations, keeping in mind the uncertainties inherent to the observations.

Rinse. Repeat.



Another method:

We have some observations.

We come up with a theory that might explain those observations.

We check how closely that theory matches the observations, given the reasonable range of parameters in the theory.

We determine what other predictions the theory might make.

We make new observations to test the other predictions.

Then see above...

yguy

That may be, but it is NOT what makes a particle behave in an unpredictable manner. That's what I'm getting at.

yguy

That may be, but it is NOT what makes a particle behave in an unpredictable manner. That's what I'm getting at.

I'm aware of that.

If you mean that behavior of particles is unpredictable at the quantum level, I'm aware of that.

I don't question that it is the best model we have. I'm suggesting that its probablistic nature makes it a candidate for re-examination on that basis alone.

It's not the universe that I think is being dodgy, but those who claim actual physical occurrences - not the theories which describe them - are "determined by probability" when the phrase is oxymoronic.

keyser_soze

I would say MOST DEFINATELY. Are you magus, just with increased typing skills?

yguy

No, because what the biologist is essentially saying is that it's not his department. The buck stops with the physicists, it appears to me.

OK, so if I understand correctly, if electrons behaved according to Newtonian physics, semiconductors wouldn't work. Fine, but that doesn't alter the fact that it is not our perception of particle motions as random that MAKE them random. Something does, and we don't know what it is.