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The growing number of elementary particles reminds me of the epicycles-upon-epicycles in the Ptolemaic system of astronomy. The question is when are we going to

by jarin 16y ago

The growing number of elementary particles reminds me of the epicycles-upon-epicycles in the Ptolemaic system of astronomy. The question is when are we going to have our "Newton moment" and figure out that they're all just manifestations of one elementary particle or string or something else?

Luc 16y ago
That would be nice, but isn't that metaphysics? The thought that there is something simple underneath it all appeals to our aesthetics, but it needn't be that way...
- jarin 16y ago
  No you're totally right, there's nothing that says it has to be that way. But since it seems that all of the elementary particles coalesced out of a relatively homogenous energy field after the Big Bang, it doesn't seem unlikely that all of the particles could be explained by tiny permutations in an underlying universal field.
- jessriedel 16y ago
  If that's metaphysics, then every famous physicist--Newton to Einstein to Feynmann--has been a strong believer in the power of metaphysics.
  - Luc 16y ago
    Well, I agree with that, it's been a fruitful heuristic, but it doesn't need to hold in every case.
  - aswanson 16y ago
    Fine, but that doesn't make the "power " any more or less valid, only that it seems to be useful thus far.
    - jessriedel 16y ago
      Well, then this just basically becomes a philosophical argument about the justification for empiricism/inductive-reasoning. Can we axiomatically prove that just because the sun has risen in the morning for the last 10,000 mornings that it will do so tomorrow? No. Neither can be sure that just because every single major advance in physics has come because of simplification/beauty that the next one will come the same way. But you'd be a fool to bet otherwise.
      - Luc 16y ago
        Well, I certainly wouldn't want to be a fool. I might be of course, especially compared to the many people I know who are smarter than myself. I think though that your argument is basically an 'appeal to ridicule' fallacy. You are making it sound like my statement is the philosophical equivalent of 'we can't be sure the sun will rise tomorrow'. It isn't, it is simple the statement that the current zoo of particles may well all be fundamental, with no 'simpler' theory underlying them. Secondly, I think your statement that 'every single major advance in physics' has been a simplification is debatable. Thirdly, extrapolating from that that every new advance will be found using the same heuristic is also debatable. If there really is to be a scientific breakthrough of the magnitude of a Newton, it seems likely (almost by definition) that it will be from an unexpected avenue of thought - seeing that the expected ones have been well researched and haven't been all that productive. I guess it makes sense to bet on a unifying theory if you are a career particle physicist. There's a Nobel prize in it. It doesn't make sense to bet on the opposite notion, since there are probably no breakthroughs that way.
        jessriedel 16y ago
        I do think your statement is the philosophical equivalent of 'we can't be sure the sun will rise tomorrow', except that it differs by degree. (The sun has risen thousands of times in my personal experience, and bazillions of times in the experience of humans, while only a handful of fundamental physics discoveries have been made.) In either case, it's a question of justifying the claim that "In situations of type A, X has always been true in the past. Therefore, in situations of type A in the future, X will be true". Likewise your simple statement that "the current zoo of particles may well all be fundamental, with no 'simpler' theory underlying them." is analogous to "the sun will collapse into a black hole tomorrow". Again, just a difference of degree. [I should stress here that the justification for empiricism is an age-old philosophical problem which isn't easy to understand, much less solve. However, I think that a proper understanding of the history of physics gives very convincing (though maybe not the-sun-will-rise convincing) evidence that simplicity and beauty will be found at the bottom of the particle zoo.] I don't understand what the true statement >If there really is to be a scientific breakthrough of the magnitude of a Newton, it seems likely (almost by definition) that it will be from an unexpected avenue of thought - seeing that the expected ones have been well researched and haven't been all that productive. has to do with our current discussion. Lastly, (basically) no career particle physicist think that any Nobel prizes will be awarded for a unifying theory in their lifetime. (See, for instance, http://www.math.columbia.edu/~woit/wordpress/?p=2998 http://www.math.columbia.edu/~woit/wordpress/?p=2998). Perhaps, if we're lucky, there will be a somewhat simplifying theory (which gets a Nobel prize) but that certainly couldn't come from the dominant research avenue, string theory.
  - tel 16y ago
    It's not just metaphysics though, right? More complex models have more moving parts and require more energy and information to specify. I feel like, in a wholly qualitative but empirically guided fashion, there is a natural savings to simplicity.
seanstickle 16y ago
Ptolemy, and his intellectual descendants, didn't actually use epicycles-on-epicycles. Just a single epicycle on a deferent. Although "epicycles-on-epicycles" might be traditionally emblematic of "incorrectly formulated over-complicated theories", it has no sound basis in the history of astronomy. The Ptolemaic model, while ineffective at meeting the measurements of planetary movement, was a fairly simple, and elegant, mathematical model.
pfedor 16y ago
Where have you seen a growing number of elementary particles? The number hasn't changed since the formulation of the Standard Model some thirty years ago.
fhars 16y ago
That has already happend in the 70ies when the unexplained zoo of hundreds of elemenary particles has been reduced to a handful of more elementary particles (12, called quarsks and leptons) and a set of dynamic theories that use even fewer bosons to describe the interactions between them. This post-copernican model of elementary particle physics is the standard model. Particle physicist have been expecting the next copernican revolution that replaces this model really soon now with the next accelerator upgrade since at least 1980 (look for example for conference talks by Haim Hariri from that time), but fundamental shifts don't happen that often.

by jarin 16y ago

Luc 16y ago

That would be nice, but isn't that metaphysics? The thought that there is something simple underneath it all appeals to our aesthetics, but it needn't be that way...

jarin 16y ago
No you're totally right, there's nothing that says it has to be that way. But since it seems that all of the elementary particles coalesced out of a relatively homogenous energy field after the Big Bang, it doesn't seem unlikely that all of the particles could be explained by tiny permutations in an underlying universal field.
jessriedel 16y ago
If that's metaphysics, then every famous physicist--Newton to Einstein to Feynmann--has been a strong believer in the power of metaphysics.
- Luc 16y ago
  Well, I agree with that, it's been a fruitful heuristic, but it doesn't need to hold in every case.
- aswanson 16y ago
  Fine, but that doesn't make the "power " any more or less valid, only that it seems to be useful thus far.
  - jessriedel 16y ago
    Well, then this just basically becomes a philosophical argument about the justification for empiricism/inductive-reasoning. Can we axiomatically prove that just because the sun has risen in the morning for the last 10,000 mornings that it will do so tomorrow? No. Neither can be sure that just because every single major advance in physics has come because of simplification/beauty that the next one will come the same way. But you'd be a fool to bet otherwise.
    - Luc 16y ago
      Well, I certainly wouldn't want to be a fool. I might be of course, especially compared to the many people I know who are smarter than myself. I think though that your argument is basically an 'appeal to ridicule' fallacy. You are making it sound like my statement is the philosophical equivalent of 'we can't be sure the sun will rise tomorrow'. It isn't, it is simple the statement that the current zoo of particles may well all be fundamental, with no 'simpler' theory underlying them. Secondly, I think your statement that 'every single major advance in physics' has been a simplification is debatable. Thirdly, extrapolating from that that every new advance will be found using the same heuristic is also debatable. If there really is to be a scientific breakthrough of the magnitude of a Newton, it seems likely (almost by definition) that it will be from an unexpected avenue of thought - seeing that the expected ones have been well researched and haven't been all that productive. I guess it makes sense to bet on a unifying theory if you are a career particle physicist. There's a Nobel prize in it. It doesn't make sense to bet on the opposite notion, since there are probably no breakthroughs that way.
      - jessriedel 16y ago
        I do think your statement is the philosophical equivalent of 'we can't be sure the sun will rise tomorrow', except that it differs by degree. (The sun has risen thousands of times in my personal experience, and bazillions of times in the experience of humans, while only a handful of fundamental physics discoveries have been made.) In either case, it's a question of justifying the claim that "In situations of type A, X has always been true in the past. Therefore, in situations of type A in the future, X will be true". Likewise your simple statement that "the current zoo of particles may well all be fundamental, with no 'simpler' theory underlying them." is analogous to "the sun will collapse into a black hole tomorrow". Again, just a difference of degree. [I should stress here that the justification for empiricism is an age-old philosophical problem which isn't easy to understand, much less solve. However, I think that a proper understanding of the history of physics gives very convincing (though maybe not the-sun-will-rise convincing) evidence that simplicity and beauty will be found at the bottom of the particle zoo.] I don't understand what the true statement >If there really is to be a scientific breakthrough of the magnitude of a Newton, it seems likely (almost by definition) that it will be from an unexpected avenue of thought - seeing that the expected ones have been well researched and haven't been all that productive. has to do with our current discussion. Lastly, (basically) no career particle physicist think that any Nobel prizes will be awarded for a unifying theory in their lifetime. (See, for instance, http://www.math.columbia.edu/~woit/wordpress/?p=2998 http://www.math.columbia.edu/~woit/wordpress/?p=2998). Perhaps, if we're lucky, there will be a somewhat simplifying theory (which gets a Nobel prize) but that certainly couldn't come from the dominant research avenue, string theory.
- tel 16y ago
  It's not just metaphysics though, right? More complex models have more moving parts and require more energy and information to specify. I feel like, in a wholly qualitative but empirically guided fashion, there is a natural savings to simplicity.

seanstickle 16y ago

Ptolemy, and his intellectual descendants, didn't actually use epicycles-on-epicycles. Just a single epicycle on a deferent. Although "epicycles-on-epicycles" might be traditionally emblematic of "incorrectly formulated over-complicated theories", it has no sound basis in the history of astronomy. The Ptolemaic model, while ineffective at meeting the measurements of planetary movement, was a fairly simple, and elegant, mathematical model.

pfedor 16y ago

Where have you seen a growing number of elementary particles? The number hasn't changed since the formulation of the Standard Model some thirty years ago.

fhars 16y ago

That has already happend in the 70ies when the unexplained zoo of hundreds of elemenary particles has been reduced to a handful of more elementary particles (12, called quarsks and leptons) and a set of dynamic theories that use even fewer bosons to describe the interactions between them. This post-copernican model of elementary particle physics is the standard model. Particle physicist have been expecting the next copernican revolution that replaces this model really soon now with the next accelerator upgrade since at least 1980 (look for example for conference talks by Haim Hariri from that time), but fundamental shifts don't happen that often.