Does Physics Have a Default View on Causation?

[Fifty]

Does physics have a generally accepted view on causation?

If so, what is it?

When I say "what is it", I mean:

-What sort of things can cause?
-What sorts of things can be caused?
-How would the sentence "x causes y if and only if __________" be filled in?

If necessary, you could seperate your answer into what non-QM physics (relativity? classical physics?) says, and what QM says.


Thanks,

Fifty Fiftyson
Historian, Antiquarian, Dentist

 

[Perfection]

Well, in classical mechanics causation is instant and universal. If a planet exploded on the other side of the galaxy, we'd feel its (extremely slight) effect on us immediately

Relativity limits the propogation to light speed.

Quantum mechanics adds some other weirdnesses. For example certain particles can only interact with certain other particles (but they can indirectly interact through intermediate particles).

A weird thing about causation in physics is that most (if not all) fundamental physics laws are the same when going backwards or forwards through time. That is if you were to watch a planet orbit around a star in reverse time, you would not notice anything unusual. It is only when the statistical behavior of many particles comes into play do laws come out that are not the same for forwards and backwards time.

 

[Kal'thzar]

wiki has it

http://en.wikipedia.org/wiki/Causality_(physics)
You should really check out all the links there

The World Line is also intresting:
http://en.wikipedia.org/wiki/World_line

Sorry I'm just C+P'ing but I've been living on wiki ever since I moved to Switzerland for the year.

 

[Mise]

I think Perf captures the essence of causality, but I'm not sure if that's what Fifty's after. If you want a strict intensional definition of causality in Physics then I'm not sure anyone here can give you one. But I can point at experiments and say what's causing what, how, and why, if you tell me what experiments to point at.

 

[Tibur753]

Well, in classical mechanics causation is instant and universal. If a planet exploded on the other side of the galaxy, we'd feel its (extremely slight) effect on us immediately

Relativity limits the propogation to light speed.

Quantum mechanics adds some other weirdnesses. For example certain particles can only interact with certain other particles (but they can indirectly interact through intermediate particles).

A better example might be that if the sun were to suddenly dissapear into nothing (If that were possible).

Classical Physics- The Earth would instanty be plunged into darkness and would continue moving in a relatively straight line in the direction that it was going before.

Relativity- We wouldn't notice any change for a few minutes because light and gravity travel at the speed of light instead of instantly. After that time, the same thing would happen.

Quantum Mechanics- I don't think that this would be any different than with relativity.

 

[Riffraff]

Maybe a more general answer would somehow simply connect particles, fields, forces and movement. I'm scared of formulating the sentance though.