Does everything have a 'cause' ? What about radioactive decay?

[plant]

unnecessary religion discussion provocative comment taken out

..but is it true that some observable events like radioactive decay really do happen for no particular reason?... are they truly random events or is it just due to current limitations in knowledge ? ....

will we eventually one day be able to say: Oh that particular uranium atom decayed then because the gluons lost a bit of energy into the 4th dimension or something.... or will this always be unknowable?

[tashirosgt]

Aristotle (as interpreted by Thomas Aquinas) pointed out that if you find A1 is "cause" for A0, then you must worry about what caused A1. If you find that A2 caused A1, you must wory about what caused A2. So you have 3 basic choices. 1) Accept that there is an infinite chain of things that caused A0 2) Accept some circular chain of causes involving A0 or 3) Believe in a "first cause", something that doesn't need anything to cause it.

Aristotle's attempts to explain physics often got tangled up in manipulating language. I don't know if this is an example of that.

[Swift]

..but is it true that some observable events like radioactive decay really do happen for no particular reason?... are they truly random events or is it just due to current limitations in knowledge ? ....

Radioactive decay does happen for a particular reason. The timing of the decay of a particular atom though is random (to the best of our current knowledge). This is true for a lot of quantum mechanical effects and QM says they are unknowable. Until a theory comes along that overturns that, that is the state of things. Personally, I don't see it happening.

[profloater]

I think random is a very dangerous word, it is not the same as unknowable. It does mean we cannot yet explain the timing of radioactive decay but perhaps there is an explanation, an information field explanation perhaps, just speculating.

[Jeff Root]

My understanding is that an unstable atomic nucleus decays
when the constituent quarks happen to come together in a way
which allows them to interact such that an energy threshold is
exceeded. The quarks are moving randomly, just like molecules
of air move randomly. With a large population of quarks, the rate
at which they come together and interact is very uniform and
predictable. But the motions of individual quarks in a nucleus
can't be followed, so there is no way to predict when the nucleus
will decay.

Profloater's reply is essentially wrong: The cause of the decay
is known, but no technology could ever make it predictable.

-- Jeff, in Minneapolis

[Glom]

How random is random? There is a probability distribution governing the timing.

[Grey]

Swift is correct that for any process governed by quantum mechanics (including radioactive decay), we are only able to give a statistical description of what will happen. That's not just a limit of how precise our measuring devices can be made, or an acknowledgment that our initial information is imperfect; it's a fundamental limitation on how much can be known even in principle about a system. From what we can tell, such processes really are fundamentally random. As far as quantum theory is concerned, if two systems are prepared in the same state, they are identical, and there is no reason that one of them gives one result when measured and a second one gives a different result, as opposed to the other way around.

However, it is also true that someone might someday come up with a replacement for quantum mechanics that is deterministic. Such a model is said to have "hidden variables", and the idea is that even if two systems are in the same state, there are some values (which we do not know how to measure, and which are probably not measurable even in principle) that further describe each system. So with such a model, the reason two systems in the same state evolve differently is that they aren't actually identical. Instead there are additional parameters that could define them, and if you knew what those parameters were, you could predict which one would go which way. It's worthwhile noting that, in order to agree with observations, any such mechanism that underlies quantum theory needs to be nonlocal. That is, the hidden variables that describe the state of a system have to be able to change in response to events or measurements that take place arbitrarily far away, without regard for the speed of light limit on communication. Models like this have been created, mostly just as an interesting exercise, since it doesn't really allow us any additional ability to predict what the results of measurements will be.

[Cobra1597]

Radioactive decay is also entropy in action. A Uranium-235 atom is larger and more ordered than its decay product, Thorium-231. It isn't happening "just because," but because the universe is constantly moving towards a more disordered state.

[Jeff Root]

Increase in entropy is a result of the decay, not a cause.

-- Jeff, in Minneapolis

[plant]

hi,

didn't mean to offend with the original post:

the question of a "1st cause' relates to the question of "what caused the big bang"?

i was asking perhaps if this is actually a non-question. Perhaps it is feasable that "nothing" caused the big bang ... just as "nothing" causes radioactive decay... just "quantum fluctuations".

so maybe a better question would be "did the big bang HAVE a cause?"

(my point about religion was that many otherwise 'agnostic' people may find the "1st cause" question a good argument for a deity...)

[Grey]

so maybe a better question would be "did the big bang HAVE a cause?"

The official mainstream answer for this one is pretty much "we have no idea". In fact, we don't really even have any good thoughts on any kind of experiment we could do or observation we could make that would let us make any headway on answering that question.

[profloater]

Swift is correct that for any process governed by quantum mechanics (including radioactive decay), we are only able to give a statistical description of what will happen. That's not just a limit of how precise our measuring devices can be made, or an acknowledgment that our initial information is imperfect; it's a fundamental limitation on how much can be known even in principle about a system. From what we can tell, such processes really are fundamentally random. As far as quantum theory is concerned, if two systems are prepared in the same state, they are identical, and there is no reason that one of them gives one result when measured and a second one gives a different result, as opposed to the other way around.

However, it is also true that someone might someday come up with a replacement for quantum mechanics that is deterministic. Such a model is said to have "hidden variables", and the idea is that even if two systems are in the same state, there are some values (which we do not know how to measure, and which are probably not measurable even in principle) that further describe each system. So with such a model, the reason two systems in the same state evolve differently is that they aren't actually identical. Instead there are additional parameters that could define them, and if you knew what those parameters were, you could predict which one would go which way. It's worthwhile noting that, in order to agree with observations, any such mechanism that underlies quantum theory needs to be nonlocal. That is, the hidden variables that describe the state of a system have to be able to change in response to events or measurements that take place arbitrarily far away, without regard for the speed of light limit on communication. Models like this have been created, mostly just as an interesting exercise, since it doesn't really allow us any additional ability to predict what the results of measurements will be.

Thank you for that, does not entanglement imply exactly such an underlying hidden variable?

[Grey]

Thank you for that, does not entanglement imply exactly such an underlying hidden variable?

Not really. Einstein was hoping that he could use entanglement, along with the assumption of locality, to show that there must be hidden variables, that quantum theory was an incomplete description of reality. Instead, Bell showed that any hidden variable model (indeed, really any mechanism that might underlie the quantum facts) must be nonlocal. It resolved the EPR "paradox" in a way that Einstein probably would have very much disliked. But there's still no requirement that there be any such hidden variables

[Ken G]

Aristotle (as interpreted by Thomas Aquinas) pointed out that if you find A1 is "cause" for A0, then you must worry about what caused A1. If you find that A2 caused A1, you must wory about what caused A2. So you have 3 basic choices. 1) Accept that there is an infinite chain of things that caused A0 2) Accept some circular chain of causes involving A0 or 3) Believe in a "first cause", something that doesn't need anything to cause it.

It seems to me that Aristotle left out a possibility, and it is the one that is the most correct: cause and effect is a convention made by intelligent analysis. There is thus no such thing as the "actual cause" of event A, it is a matter of context and what we are invoking the concept of "cause" for in the first place. Consider the old claim that "guns don't kill people, people do" followed by the joke "guns don't kill people, bullets do." A cause is what we make it, it depends on what we want from the concept. Personally, I don't think nature, independently of intelligence, has any need to distinguish a cause from an effect, there are simply interrelationships between things that happen. There are constraints, not causes.

A point I made in another thread going on right now is that the basic equations of physics are almost all time reversible. This means that on a physics exam, you could just as easily be asked to take the current data of some situation and figure out what it will likely be a second later, or a second earlier. The questions are identical, there is no difference at all between a cause and an effect. It is a convention of language.

This even extends to the second law of thermodynamics. Basically, all that law says is, if you take a situation that is special in some way, then subject to the constraints of the situation, if you run time either backward or forward it will evolve into a situation that is more generic. Hence there is no arrow of time there, and no distinction between a cause and an effect. The arrow of time, and the distinction, comes from probabilistic assumptions that we make about what class of possibilities we are choosing from. This is much like a person playing poker-- each player, even in exactly the same situation, my assess the probabilities differently, based on how they pick the classes they are choosing from. So poker strategy is an analysis technique that results in some goal being achieved, and the whole concept of cause and effect is exactly like that-- a means to an end, carried out by an intelligence.