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> "Is the universe fundamentally deterministic?" The best answer we have to date is "Nobody knows," to which I would add, "nor do we know how to find out." I

by spodek 13y ago

> "Is the universe fundamentally deterministic?" The best answer we have to date is "Nobody knows," to which I would add, "nor do we know how to find out." I see no shame in that answer. I'm surprised nobody suggested that answer so far, unless I missed it. That doesn't mean we'll never find out or make any progress, but we don't know now. Personally, I see value in such a direct answer. If the question is "Are the laws of physics as we know them deterministic?" that's a question about human knowledge and the most effective equations and interpretations of them we have. We can answer that question definitively, but that doesn't answer the original question about the universe itself. If the question is about the universe itself, all we can offer is the laws of physics we know, which brings us back to the first point. We have incomplete knowledge of the universe. No experiment has been done yet to conclusively answer the question, so all we have is opinion. Anyone suggesting otherwise either knows of an experiment I don't (I'd be overjoyed to find out), or stating mere opinion. Opinion is nice, but it answers the question "Do you think the universe is deterministic," which is not the question asked. Edit: I see someone put this answer on the original site.

sillysaurus2 13y ago
The best answer we have to date is "Nobody knows," to which I would add, "nor do we know how to find out." I see no shame in that answer. I'm surprised nobody suggested that answer so far, unless I missed it. Well, it's stack exchange. You can't answer in a way that implies you don't know. They force answerers to act like everything is known, and that they personally know everything. Example: http://gamedev.stackexchange.com/questions/65768/how-can-i-deal-with-actor-translations-and-other-noise-in-third-party-motion-c/65769#65769 http://gamedev.stackexchange.com/questions/65768/how-can-i-d...
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.
    - 13y ago
ambler0 13y ago
I would go even one farther: There is, in principle, no way to find out. At any level description, it's still always possible to ask whether there is an even deeper level of description, whether there are yet more undiscovered entities, etc. How would you ever know when you've reached 'the end'? While our scientific models are clearly in some sense about The World, they are still just models, and as dependent on the properties of our own minds as they are on the World. Some sort of direct-knowledge of The World is a nebulous concept. I think many people have made this point, but it is perhaps most associated with the philosophy Immanuel Kant, who made the distinction between noumena, or 'the-world-in-itself', and phenomena, 'the-world-for-us'.

by spodek 13y ago

sillysaurus2 13y ago

The best answer we have to date is "Nobody knows," to which I would add, "nor do we know how to find out." I see no shame in that answer. I'm surprised nobody suggested that answer so far, unless I missed it. Well, it's stack exchange. You can't answer in a way that implies you don't know. They force answerers to act like everything is known, and that they personally know everything. Example: http://gamedev.stackexchange.com/questions/65768/how-can-i-deal-with-actor-translations-and-other-noise-in-third-party-motion-c/65769#65769 http://gamedev.stackexchange.com/questions/65768/how-can-i-d...

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.
  - 13y ago

ambler0 13y ago

I would go even one farther: There is, in principle, no way to find out. At any level description, it's still always possible to ask whether there is an even deeper level of description, whether there are yet more undiscovered entities, etc. How would you ever know when you've reached 'the end'? While our scientific models are clearly in some sense about The World, they are still just models, and as dependent on the properties of our own minds as they are on the World. Some sort of direct-knowledge of The World is a nebulous concept. I think many people have made this point, but it is perhaps most associated with the philosophy Immanuel Kant, who made the distinction between noumena, or 'the-world-in-itself', and phenomena, 'the-world-for-us'.