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>Universes do not split like that. That would mean many universes were being created from nothing every instant. What actually happens is there are already infi

>Universes do not split like that. That would mean many universes were being created from nothing every instant. What actually happens is there are already infinitely many "universes" and they become different. And not one per outcome, but in proportion to the probability of outcomes. It's not the writers of the article who have no clue. It's quantum physicists themselves. In the Copenhagen interpretation of QM, a conscious observer induces wave collapse (a random process). In this interpretation, there are no other worlds. In Wave Collapse/Many Worlds, a parallel universe is created in which wave collapse occured but gave a different outcome. There are different interpretations of QM (e.g. bohmian mechanics or GRW/stochastic collapse) which don't have this problem. If you are interested in QM, I strongly suggest looking these theories up. But Copenhagen QM (the theory in most textbooks) does have this problem. The reporter did an adequate job of explaining the consensus view. The problem is really that the consensus view can allow for nonsense such as what was described in the article.

pfedor 19y ago
"There are different interpretations of QM (e.g. bohmian mechanics or GRW/stochastic collapse) which don't have this problem. If you are interested in QM, I strongly suggest looking these theories up." I respectfully disagree. You can spend years reading about interpretations and the gain in terms of your understanding of Quantum Mechanics will be zero. For anyone interested in Quantum Mechanics, I strongly suggest actually trying to learn it, instead of dabbling into confusing popular articles the authors of the majority of which have never studied theoretical physics themselves. Please note I'm not saying that you don't know Quantum Mechanics. I just think your advice is bad. So here's my advice to anyone out there who feels that they want to know more. See the Schroedinger equation. Learn how to calculate energy levels for the harmonic oscillator and for the hydrogen atom. Read first six chapter's of Paul Dirac's "The principles of quantum mechanics". The time spent reading about interpretations and philosophical implications of QM is wasted. People who do research in theoretical physics devote very little time to such considerations, or no at all.
curi 19y ago
In Wave Collapse/Many Worlds, a parallel universe is created in which wave collapse occured but gave a different outcome. That is incorrect. Many Worlds does not say universes are created all the time, it says they already exist and become differentiated. BTW all the other interpretations are ridiculous attempts to avoid facing counter-intuitive facts. See, for example, David Deutsch's speech at the recent Everett conference http://www.philosophy.ox.ac.uk/misc/everett/Deutsch%20-%20Apart.wmv http://www.philosophy.ox.ac.uk/misc/everett/Deutsch%20-%20Ap...
- hugh 19y ago
  <i>That is incorrect. Many Worlds does not say universes are created all the time, it says they already exist and become differentiated.</i> Actually there's no real consensus on that point, even among many-worlds theorists. Some folks suggest that universes "split", others suggest that they "become differentiated", and a third set of folks say that they do something which isn't really properly described by either of the above options. Deutsch has one of the more widely publicised many-worlds interpretations, but it's not the only one out there, and it's not necessarily the most widely accepted.
  - curi 19y ago
    I don't really care what views are popular, (though MWI is popular among top experts to whom it matters), I care which views are true. So what matters to me is which proponents say things that make sense and give good explanations and arguments. Deutsch does, including a powerful and concise argument in chapter 2 of his book. When someone gives a reasonable counter argument then I will reconsider, but that has not happened. And, of course, Deutsch isn't the only example of the MWI side making more sense. Here is another source: http://www.hedweb.com/manworld.htm http://www.hedweb.com/manworld.htm Edit: If you can give a non-ridiculous summary of any other interpretation, go ahead...
    - angryprofessor 19y ago
      Some of the many worlds variants make sense. I prefer bohmian mechanics (I can reason about it better), but I have no objection to MW. Ultimately I don't care one way or the other: the predictions for MY universe are the same, whether or not it is unique or one amoung many. However, the point I was making is that most physicists believe in wave collapse. The writer of the article was simply providing a reasonably good summary of QM with wave collapse. According to Q1 of your article, this is still a mainstream belief except amoung string theorists, apparently. I agree, it's almost certainly wrong. But that's not yet a mainstream position. As for other non-ridiculous interpretations, just look at bohmian mechanics or GRW. Bohmian mechanics postulates that particles exist and are guided by the wave function. The testable physical predictions are identical to many worlds. GRW makes different physical predictions (possibly testable in the near future), but the theory makes sense as well.

pfedor 19y ago

"There are different interpretations of QM (e.g. bohmian mechanics or GRW/stochastic collapse) which don't have this problem. If you are interested in QM, I strongly suggest looking these theories up." I respectfully disagree. You can spend years reading about interpretations and the gain in terms of your understanding of Quantum Mechanics will be zero. For anyone interested in Quantum Mechanics, I strongly suggest actually trying to learn it, instead of dabbling into confusing popular articles the authors of the majority of which have never studied theoretical physics themselves. Please note I'm not saying that you don't know Quantum Mechanics. I just think your advice is bad. So here's my advice to anyone out there who feels that they want to know more. See the Schroedinger equation. Learn how to calculate energy levels for the harmonic oscillator and for the hydrogen atom. Read first six chapter's of Paul Dirac's "The principles of quantum mechanics". The time spent reading about interpretations and philosophical implications of QM is wasted. People who do research in theoretical physics devote very little time to such considerations, or no at all.

curi 19y ago

In Wave Collapse/Many Worlds, a parallel universe is created in which wave collapse occured but gave a different outcome. That is incorrect. Many Worlds does not say universes are created all the time, it says they already exist and become differentiated. BTW all the other interpretations are ridiculous attempts to avoid facing counter-intuitive facts. See, for example, David Deutsch's speech at the recent Everett conference http://www.philosophy.ox.ac.uk/misc/everett/Deutsch%20-%20Apart.wmv http://www.philosophy.ox.ac.uk/misc/everett/Deutsch%20-%20Ap...

hugh 19y ago
<i>That is incorrect. Many Worlds does not say universes are created all the time, it says they already exist and become differentiated.</i> Actually there's no real consensus on that point, even among many-worlds theorists. Some folks suggest that universes "split", others suggest that they "become differentiated", and a third set of folks say that they do something which isn't really properly described by either of the above options. Deutsch has one of the more widely publicised many-worlds interpretations, but it's not the only one out there, and it's not necessarily the most widely accepted.
- curi 19y ago
  I don't really care what views are popular, (though MWI is popular among top experts to whom it matters), I care which views are true. So what matters to me is which proponents say things that make sense and give good explanations and arguments. Deutsch does, including a powerful and concise argument in chapter 2 of his book. When someone gives a reasonable counter argument then I will reconsider, but that has not happened. And, of course, Deutsch isn't the only example of the MWI side making more sense. Here is another source: http://www.hedweb.com/manworld.htm http://www.hedweb.com/manworld.htm Edit: If you can give a non-ridiculous summary of any other interpretation, go ahead...
  - angryprofessor 19y ago
    Some of the many worlds variants make sense. I prefer bohmian mechanics (I can reason about it better), but I have no objection to MW. Ultimately I don't care one way or the other: the predictions for MY universe are the same, whether or not it is unique or one amoung many. However, the point I was making is that most physicists believe in wave collapse. The writer of the article was simply providing a reasonably good summary of QM with wave collapse. According to Q1 of your article, this is still a mainstream belief except amoung string theorists, apparently. I agree, it's almost certainly wrong. But that's not yet a mainstream position. As for other non-ridiculous interpretations, just look at bohmian mechanics or GRW. Bohmian mechanics postulates that particles exist and are guided by the wave function. The testable physical predictions are identical to many worlds. GRW makes different physical predictions (possibly testable in the near future), but the theory makes sense as well.