6 ms·

Until someone can explain otherwise, I defer to Dr. Feynman, who essentially tells us that probability is intrinsic to the universe itself, and our experience o

by Arjuna 13y ago

Until someone can explain otherwise, I defer to Dr. Feynman, who essentially tells us that probability is intrinsic to the universe itself, and our experience of reality. I love the line that says (from the quote, below), "Someone has said it this way: 'nature herself doesn't know which way the electron is going to go.'" When discussing the double-slit experiment, he said: "It is not a lack of unknown gears - a lack of internal complications - that makes nature have probability in it; it seems to be in some sense intrinsic. Someone has said it this way: 'nature herself doesn't know which way the electron is going to go.' A philosopher once said (a pompous one): 'it is necessary for the very existence of science that the same conditions always produce the same result.' Well, they don't: if you set up electrons in any way - I mean, you set up the circumstance here, in the same conditions every time, and you cannot predict behind which hole you'll see the electron. They don't - and yet the science goes on in spite of him." -- Watch the full lecture here: https://www.youtube.com/watch?v=hUJfjRoxCbk https://www.youtube.com/watch?v=hUJfjRoxCbk I posted a transcribed portion previously: https://news.ycombinator.com/item?id=3756989 https://news.ycombinator.com/item?id=3756989

mtdewcmu 13y ago
I'm probably taking Feynman out of context here, but I think philosopher is almost right, and Feynman is being a tad pompous. I think it's necessary to some extent to assume that the same conditions always produce the same result in order to do science. Otherwise, why do experiments? If the universe deviated slightly from determinism, it probably wouldn't make science impossible to do, and since I don't think science can actually test determinism, it's outside the scope of science and must be assumed. It seems a bit pompous to say that we've set up electrons the same way and observed that they go in two different directions for no reason. You can't eliminate reasons that you don't know about.
- ByronT 13y ago
  It seems a bit pompous to say that we've set up electrons the same way and observed that they go in two different directions for no reason. You can't eliminate reasons that you don't know about. Have you heard about the EPR paradox [1]? Einstein, Podolsky, and Rosen believed there may have been "hidden variables" in the language of quantum mechanics which were not yet accounted for. These hidden variables, if discovered, would render quantum mechanics more deterministic. This idea was essentially shattered by Bell's theorem [2]. The universe probably is not deterministic (at least in the sense we think about determinism). That's a hard pill to swallow, and it goes against all human intuition. But the majority of physicists do seem to accept this fact, however uncomfortable it might initially feel. [1] http://en.wikipedia.org/wiki/EPR_paradox http://en.wikipedia.org/wiki/EPR_paradox [2] http://en.wikipedia.org/wiki/Bell%27s_theorem http://en.wikipedia.org/wiki/Bell%27s_theorem
  - dragonwriter 13y ago
    > The universe probably is not deterministic (at least in the sense we think about determinism). That's a hard pill to swallow, and it goes against all human intuition. It really doesn't contradict "all human intuition". Strong determinism has always been a controversial position, though its popular with the people that view science as a new complete-and-all-encompassing religion rather than a utilitarian tool.
  - mtdewcmu 13y ago
    "Probably is not deterministic" is not quite the same as "provably is not deterministic." Physicists have opinions on a lot of things, but I don't think they can fundamentally answer this.
    - ByronT 13y ago
      In your original post, you state that we might as well assume determinism. Why? Given the widely accepted nondeterminism of quantum behavior, why wouldn't we assume nondeterminism instead? I realize what you're grasping at is that deterministic behavior might somehow underly this seemingly nondeterministic behavior. Bell's theorem, however, has made it difficult to reject that the this fundamental aspect of the universe is hard to explain without assuming nondeterminism (or superdeterminism). I agree you can't prove it. You just haven't really explained why you're leaning toward the deterministic side.
      - mtdewcmu 13y ago
        I didn't make myself clear. I meant assume in the mathematical sense, as in, to take as an axiom. If you do a science experiment, you are assuming that you will get back a repeatable result, and you won't be measuring something perfectly random. Otherwise, people might assume you're crazy. :)

by Arjuna 13y ago

mtdewcmu 13y ago

I'm probably taking Feynman out of context here, but I think philosopher is almost right, and Feynman is being a tad pompous. I think it's necessary to some extent to assume that the same conditions always produce the same result in order to do science. Otherwise, why do experiments? If the universe deviated slightly from determinism, it probably wouldn't make science impossible to do, and since I don't think science can actually test determinism, it's outside the scope of science and must be assumed. It seems a bit pompous to say that we've set up electrons the same way and observed that they go in two different directions for no reason. You can't eliminate reasons that you don't know about.

ByronT 13y ago
It seems a bit pompous to say that we've set up electrons the same way and observed that they go in two different directions for no reason. You can't eliminate reasons that you don't know about. Have you heard about the EPR paradox [1]? Einstein, Podolsky, and Rosen believed there may have been "hidden variables" in the language of quantum mechanics which were not yet accounted for. These hidden variables, if discovered, would render quantum mechanics more deterministic. This idea was essentially shattered by Bell's theorem [2]. The universe probably is not deterministic (at least in the sense we think about determinism). That's a hard pill to swallow, and it goes against all human intuition. But the majority of physicists do seem to accept this fact, however uncomfortable it might initially feel. [1] http://en.wikipedia.org/wiki/EPR_paradox http://en.wikipedia.org/wiki/EPR_paradox [2] http://en.wikipedia.org/wiki/Bell%27s_theorem http://en.wikipedia.org/wiki/Bell%27s_theorem
- dragonwriter 13y ago
  > The universe probably is not deterministic (at least in the sense we think about determinism). That's a hard pill to swallow, and it goes against all human intuition. It really doesn't contradict "all human intuition". Strong determinism has always been a controversial position, though its popular with the people that view science as a new complete-and-all-encompassing religion rather than a utilitarian tool.
- mtdewcmu 13y ago
  "Probably is not deterministic" is not quite the same as "provably is not deterministic." Physicists have opinions on a lot of things, but I don't think they can fundamentally answer this.
  - ByronT 13y ago
    In your original post, you state that we might as well assume determinism. Why? Given the widely accepted nondeterminism of quantum behavior, why wouldn't we assume nondeterminism instead? I realize what you're grasping at is that deterministic behavior might somehow underly this seemingly nondeterministic behavior. Bell's theorem, however, has made it difficult to reject that the this fundamental aspect of the universe is hard to explain without assuming nondeterminism (or superdeterminism). I agree you can't prove it. You just haven't really explained why you're leaning toward the deterministic side.
    - mtdewcmu 13y ago
      I didn't make myself clear. I meant assume in the mathematical sense, as in, to take as an axiom. If you do a science experiment, you are assuming that you will get back a repeatable result, and you won't be measuring something perfectly random. Otherwise, people might assume you're crazy. :)