6 ms·

A Crisis at the Edge of Physics

43 points by RyanGWU82 11y ago

ISL 11y ago
Experiment is the arbiter of truth. Without it, how could you know what's true?
- lnanek2 11y ago
  For most professionals in this field, what's true is pretty irrelevant. Only what brings in funding is what matters. That's why unprovable theories have so much success. It's much better to have something no one can prove wrong and destroy your career than have something that can be. Newton was proved wrong by Einstein, after all, being shown to just be an approximation compared to relativity. So the next step forward is to make sure your theory can't suffer like that and dry up your funding. The next step forward for these people isn't more accurate models and truth, it is more fundable ones.
  - ISL 11y ago
    I am a professional in the field :). I make precision experimental tests of gravity. If a line of physical theory never leads to something testable, is it a physical theory? Elegance and beauty are major guiding lights for theory, but they can't be the end goal if our desire is to learn the nature of Nature. Arkani-Hamed and others chasing the physical utility of the Grassmanian are a modern example of beautiful mathematics straining toward physically-testable theory. I expect you'll see more money flowing that way in the next few years.
- ctdavies 11y ago
  http://plato.stanford.edu/entries/truth/ http://plato.stanford.edu/entries/truth/
jamesrcole 11y ago
The article fails to clearly distinguish two issues: what we take to be true, and what we choose to work on for the moment. We need evidence backing up what we take to be true. But we can and must be able to work on ideas without evidence for their truth. We must be given time to flash them out, to try and find ways to get evidence for them. Wanting to pursue a possible explanation is not the same as believing that it's true.
- kijin 11y ago
  Exactly. Many of the people who work on string theory obviously believe it to be true in one way or another; it's hard to stay motivated otherwise. But the rest of the world need not care whether it is true or not. For the time being, it's just one untested hypothesis among many. It can take years (or even decades) for a theory to grow to the point where it can produce testable hypotheses, and more decades (sometimes even centuries) to test those hypotheses. This is especially true for theories that deal with extreme scales of space and/or time, such as cosmology, geology, paleontology, and (at the other extreme) anything that deals with subatomic particles. Gravitational waves [1], for example, have been predicted for almost a century now, but we still don't seem to know how to build a machine to detect them. The last time this topic came up, I wrote a response titled "Why so impatient?" I'll leave the link below [2] in case anyone is interested. [1] https://en.wikipedia.org/wiki/Gravitational_wave https://en.wikipedia.org/wiki/Gravitational_wave [2] https://www.kijinsung.com/post/why-so-impatient https://www.kijinsung.com/post/why-so-impatient
  - glaberficken 11y ago
    Really liked your article =) Long term thinking is really hard to do these days. I'm 36 and my generation seems to take for granted that everything evolves at the same pace as most 20th century technologies have done so far. This seems to be compounded by the prevalent market driven logic that prioritizes short term profit above all. Putting these things in their correct historic timescale is very insight-full. thank you =)
  - henriquemaia 11y ago
    Thanks for sharing your article on this matter. It's very enlightening.
loup-vaillant 11y ago
There's a difference between the epicycles and the multiverse (assuming we're talking about quantum decoherence, I don't really know about the others). See, the epicycles really were additional entities, and therefore a problem, with respect to Occam's razor. Quantum decoherence is different: it merely follows the equations, and do not posit any additional entity on top of them (such as a collapse). The consequence of removing that entity is multiple universes, but so what? The problem with science is that it tends to favour the first theory that fits the fact. Instead, it should favour the simplest theory that fits the fact. http://lesswrong.com/lw/qa/the_dilemma_science_or_bayes/ http://lesswrong.com/lw/qa/the_dilemma_science_or_bayes/
- z92 11y ago
  I still find basically both epicycle and multiverse theories on the same level. That multiverse theory replaced other theories (like collapse) doesn't make a meaningful difference, as probably epicycle explanation also replaced other more complex theories that were floating around at that time trying to explain the backward motion of the planets.
  - loup-vaillant 11y ago
    Ellipses are more counter-intuitive, compared to circles, but epicycles are still more complex than ellipses. Not to mention, ellipses are explained by something even simpler, namely Newton mechanics. Many World Interpretation is not like the epicycles. It is like the ellipses. It's the Copenhagen interpretation that is like the epicycles, by postulating a collapse that the equations don't mention at all. The MWI is just taking the equations at face values. Postulating a collapse on top of that makes a more complex theory. If many world came first, the collapse postulate would just be laughed at. "You're postulating a collapse in just the parts of our universe we can't observe? That reeks of "if I can't see it, it doesn't exists. If you're going to push that theory, you'd better produce empirical evidence."
    - jules 11y ago
      Note that the multiverse that this article is talking about is very different than the many worlds multiverse. The many worlds multiverse is just that the whole universe is in a quantum state. The multiverse that this article is talking about is different. Due to the expansion of space we can only see some finite region around us. If you go far enough away, then the expansion of space between that point and the earth is faster than the speed of light, so we can never reach that point, and nothing from that point can reach us. Effectively we are in a different universe than that point. The multiverse theory is that some things that appear constant in our part of the universe, such as the fine structure constant, may well be not exactly constant. Then it could be the case that the fine structure constant in that far away part of space that we can never reach is different than our fine structure constant. Then because the universe continues to expand, regions that were connected become disconnected. So one region with fine structure constant x may split into two regions one with fine structure constant x + 0.0002 and another with fine structure constant x - 0.0001. That process creates an infinite tree of regions. If a region happens to have physical "constants" that create deflation rather than inflation, that branch of the tree dies. By the anthropic principle we live in a region with properties that produce humans. By the way, I don't get the obsession with quantum mechanics interpretations. Copenhagen and many worlds give exactly the same predictions, so if one is correct then so is the other. Who cares how you choose to interpret it. By analogy to probability theory, Copenhagen is like conditioning on an observation, many worlds is like looking at the whole probability distribution. These are just two ways of looking at the same thing. It's as silly as arguing whether the Hamiltonian or Lagrangian formulation of classical mechanics is correct. Both are.
mahranch 11y ago
What this article fails to take into account is the underlying politics at play here. You might think of all places, that science would be "politics free" but it's not. Far, far from it. For example, people working on string theory and people working on say, quantum loop gravity are somewhat at odds with one another. String theory may not see the QLG people as a direct threat but the QLG people certainly sees string theory as competition. Now you may wonder, "In competition for what?" and the answer to that is a bit more obvious: Funding (money for research and their very own paychecks) and attention from their peers/media/press/etc. These people's very livelihoods are at stake. If QLG was proven wrong tomorrow, it's not like the people who were doing that for the last 15 years can just jump into another field. There's plenty of incentive for "hostile science" as I like to call it. There have been some well-known physicists who have written entire books bashing their competition for this purpose (See: Peter Woit's "Not Even Wrong", which incidentally, is chuck full of so many inaccuracies someone else wrote a book disputing his book...) So when I see articles like these, I like to check out who the author is. Do they have a reason to write this piece? In this case, it's Adam Frank and Marcelo Gleiser. Both are coincidentally astrophysicists at very respected universities. I wonder what they're working on? It appears Marcelo Gleiser, one of the authors, just published an anti-String theory book which claims that "We don't need a Theory of Everything".
- DennisP 11y ago
  Yes, but it's possible that the points they raised were the reason they took that side of the debate. I don't think it's really useful to question people's motives, rather than just considering their arguments.
  - protomyth 11y ago
    "I don't think it's really useful to question people's motives, rather than just considering their arguments." In an ideal world the argument should stand alone, but I find people's motives to be worth considering. Not for the usual you'll find in the media like looking for the corrupt or using those motives to dismiss their arguments. I find how people come to their beliefs to be really interesting. I can learn from the path they took even if I find the result to be broken. The danger is admiring the path and supporting the broken argument. As to the politics. Two people interacting means that you will have politics. Humans have conflicts from the battlefield to the soapbox to the pulpit to the lecture hall.
jordanpg 11y ago
This article strikes me as having lost its focus in editing somehow. One can hardly blame theoretical physicists for exploring above and beyond what the experimentalists are doing. It's not like there's a large body of more practical, down-to-earth problems being ignored in favor of these sexier, Nobel-bait questions. I believe the point is that we are in trouble if something exciting doesn't happen at LHC; in this case, getting the planet to fund an O($1T) accelerator to probe higher energy levels seems far-fetched. Theorists know this. This is a closely related point to the comment about the politics of theory. I don't know that this automatically spells crisis. There are plenty of problems out there that require the mathematical talent of folks that can perform at this level. Eventually, when more data is available, the pendulum will swing back towards interesting theory. After all, it's not the case that if there isn't some rush to a GUT before 2020, the human race loses.
- nn3 11y ago
  Modern physics currently cannot explain what most of the universe is made of, as in the dark matter problem. While not exactly "down to earth" this would seem like a very pressing problem to me, that may be in need of more attention.
  - jordanpg 11y ago
    While I am as convinced as you about the urgency of these issues in the context of physics itself, a crisis it is not. Not for physicists and certainly not for civilians.
    - aminorex 11y ago
      You say that now, but when your sailboat gets eaten by a dark matter kraken you will sing a different song.
coldcode 11y ago
I wonder if our understanding of the universe will ultimately exceed our ability to reason about it. Complexity can increase without bound but our brain's capacity to understand and model isn't increasing at all. Maybe we should find some way to make smarter physicists.
- escherplex 11y ago
  Very Zen. The failure to recognize the limitations of one's received cognitive instrumentation. And this instrumentation is empirically oriented so without empirical validation what have you got? And with emphasis placed on theories which are 'sufficiently elegant and explanatory' while setting aside the need for experimental confirmation merely sets the theorist up for 'The great tragedy of Science — the slaying of a beautiful hypothesis by an ugly fact' (Thomas Huxley)
javajosh 11y ago
This is very frustrating for those of us that see the rather large problem in front of us - our apparent total inability to move around the stars, and only feeble ability to move around our solar system. This caps the lifespan of humanity (and most of the life we know) at about 500k years at best. So, even if we succeed wildly at our environmental and social problems, we'll end up with a single beautiful world getting smashed to bits by a meteor, gamma burst, or other uncontrollable, unavoidable cosmic event. Physicists need to get their heads out of their political/philosophical asses and start earning their bread - which is nothing less than to justify our technological existence by discovering the knowledge that will help our species live longer. If not for this, I think we'd all be better off living on a planet of 200M people living in rural villages, leading simple lives that are as happy and fair and erudite as fate and culture allows.
- drjesusphd 11y ago
  Plenty of us are working on nuclear fusion, but funding keeps getting cut year after year. It's simply not as sexy and doesn't get as much attention as the cosmological kinds of questions.
Animats 11y ago
This is mostly a problem with string theory. Here's a popular version of a critique.[1] Smolin's 2006 "The trouble with physics" is a book-length critique of it. Peter Woit' s "Not Even Wrong: The Failure of String Theory & the Continuing Challenge to Unify the Laws of Physics" is even more critical. It's been a decade since that, and the experimental evidence for string theory remains nonexistent. As Fred Hoyle once wrote, "Science is prediction, not explanation". A theory with no experimental support cannot lead to usable technology, either. Fundamental physics is currently stuck. There's a lot of denial about this. There's a whole generation of string theory faculty in senior positions. That's the problem. [1] http://www.theguardian.com/science/2006/oct/08/research.highereducation http://www.theguardian.com/science/2006/oct/08/research.high...
- TheOtherHobbes 11y ago
  I know someone with a PhD in string theory. He eventually left the field - not just because it was (as he put it) "mostly bullshit", but because the popularity of the field was based on distortingly aggressive academic PR and self-promotion by rather too many researchers in the string theory community. The other problem for physics is that so much of the talent works on Wall St doing things that are - for all practical purposes - useless, if not counterproductive. So physics is stuck for two reasons, and won't start moving again until the culture changes enough to fix both problems. Given the declining (political) value of long-term theoretical research in academia, and the relative impossibility of doing an original PhD exploring ideas outside the mainstream, I'm not expecting change any time soon. This is beyond tragedy, because in terms of medium-term human survival, nothing is more important than new science.

43 points by RyanGWU82 11y ago

ISL 11y ago

Experiment is the arbiter of truth. Without it, how could you know what's true?

lnanek2 11y ago
For most professionals in this field, what's true is pretty irrelevant. Only what brings in funding is what matters. That's why unprovable theories have so much success. It's much better to have something no one can prove wrong and destroy your career than have something that can be. Newton was proved wrong by Einstein, after all, being shown to just be an approximation compared to relativity. So the next step forward is to make sure your theory can't suffer like that and dry up your funding. The next step forward for these people isn't more accurate models and truth, it is more fundable ones.
- ISL 11y ago
  I am a professional in the field :). I make precision experimental tests of gravity. If a line of physical theory never leads to something testable, is it a physical theory? Elegance and beauty are major guiding lights for theory, but they can't be the end goal if our desire is to learn the nature of Nature. Arkani-Hamed and others chasing the physical utility of the Grassmanian are a modern example of beautiful mathematics straining toward physically-testable theory. I expect you'll see more money flowing that way in the next few years.
ctdavies 11y ago
http://plato.stanford.edu/entries/truth/ http://plato.stanford.edu/entries/truth/

jamesrcole 11y ago

The article fails to clearly distinguish two issues: what we take to be true, and what we choose to work on for the moment. We need evidence backing up what we take to be true. But we can and must be able to work on ideas without evidence for their truth. We must be given time to flash them out, to try and find ways to get evidence for them. Wanting to pursue a possible explanation is not the same as believing that it's true.

kijin 11y ago
Exactly. Many of the people who work on string theory obviously believe it to be true in one way or another; it's hard to stay motivated otherwise. But the rest of the world need not care whether it is true or not. For the time being, it's just one untested hypothesis among many. It can take years (or even decades) for a theory to grow to the point where it can produce testable hypotheses, and more decades (sometimes even centuries) to test those hypotheses. This is especially true for theories that deal with extreme scales of space and/or time, such as cosmology, geology, paleontology, and (at the other extreme) anything that deals with subatomic particles. Gravitational waves [1], for example, have been predicted for almost a century now, but we still don't seem to know how to build a machine to detect them. The last time this topic came up, I wrote a response titled "Why so impatient?" I'll leave the link below [2] in case anyone is interested. [1] https://en.wikipedia.org/wiki/Gravitational_wave https://en.wikipedia.org/wiki/Gravitational_wave [2] https://www.kijinsung.com/post/why-so-impatient https://www.kijinsung.com/post/why-so-impatient
- glaberficken 11y ago
  Really liked your article =) Long term thinking is really hard to do these days. I'm 36 and my generation seems to take for granted that everything evolves at the same pace as most 20th century technologies have done so far. This seems to be compounded by the prevalent market driven logic that prioritizes short term profit above all. Putting these things in their correct historic timescale is very insight-full. thank you =)
- henriquemaia 11y ago
  Thanks for sharing your article on this matter. It's very enlightening.

loup-vaillant 11y ago

There's a difference between the epicycles and the multiverse (assuming we're talking about quantum decoherence, I don't really know about the others). See, the epicycles really were additional entities, and therefore a problem, with respect to Occam's razor. Quantum decoherence is different: it merely follows the equations, and do not posit any additional entity on top of them (such as a collapse). The consequence of removing that entity is multiple universes, but so what? The problem with science is that it tends to favour the first theory that fits the fact. Instead, it should favour the simplest theory that fits the fact. http://lesswrong.com/lw/qa/the_dilemma_science_or_bayes/ http://lesswrong.com/lw/qa/the_dilemma_science_or_bayes/

z92 11y ago
I still find basically both epicycle and multiverse theories on the same level. That multiverse theory replaced other theories (like collapse) doesn't make a meaningful difference, as probably epicycle explanation also replaced other more complex theories that were floating around at that time trying to explain the backward motion of the planets.
- loup-vaillant 11y ago
  Ellipses are more counter-intuitive, compared to circles, but epicycles are still more complex than ellipses. Not to mention, ellipses are explained by something even simpler, namely Newton mechanics. Many World Interpretation is not like the epicycles. It is like the ellipses. It's the Copenhagen interpretation that is like the epicycles, by postulating a collapse that the equations don't mention at all. The MWI is just taking the equations at face values. Postulating a collapse on top of that makes a more complex theory. If many world came first, the collapse postulate would just be laughed at. "You're postulating a collapse in just the parts of our universe we can't observe? That reeks of "if I can't see it, it doesn't exists. If you're going to push that theory, you'd better produce empirical evidence."
  - jules 11y ago
    Note that the multiverse that this article is talking about is very different than the many worlds multiverse. The many worlds multiverse is just that the whole universe is in a quantum state. The multiverse that this article is talking about is different. Due to the expansion of space we can only see some finite region around us. If you go far enough away, then the expansion of space between that point and the earth is faster than the speed of light, so we can never reach that point, and nothing from that point can reach us. Effectively we are in a different universe than that point. The multiverse theory is that some things that appear constant in our part of the universe, such as the fine structure constant, may well be not exactly constant. Then it could be the case that the fine structure constant in that far away part of space that we can never reach is different than our fine structure constant. Then because the universe continues to expand, regions that were connected become disconnected. So one region with fine structure constant x may split into two regions one with fine structure constant x + 0.0002 and another with fine structure constant x - 0.0001. That process creates an infinite tree of regions. If a region happens to have physical "constants" that create deflation rather than inflation, that branch of the tree dies. By the anthropic principle we live in a region with properties that produce humans. By the way, I don't get the obsession with quantum mechanics interpretations. Copenhagen and many worlds give exactly the same predictions, so if one is correct then so is the other. Who cares how you choose to interpret it. By analogy to probability theory, Copenhagen is like conditioning on an observation, many worlds is like looking at the whole probability distribution. These are just two ways of looking at the same thing. It's as silly as arguing whether the Hamiltonian or Lagrangian formulation of classical mechanics is correct. Both are.

mahranch 11y ago

What this article fails to take into account is the underlying politics at play here. You might think of all places, that science would be "politics free" but it's not. Far, far from it. For example, people working on string theory and people working on say, quantum loop gravity are somewhat at odds with one another. String theory may not see the QLG people as a direct threat but the QLG people certainly sees string theory as competition. Now you may wonder, "In competition for what?" and the answer to that is a bit more obvious: Funding (money for research and their very own paychecks) and attention from their peers/media/press/etc. These people's very livelihoods are at stake. If QLG was proven wrong tomorrow, it's not like the people who were doing that for the last 15 years can just jump into another field. There's plenty of incentive for "hostile science" as I like to call it. There have been some well-known physicists who have written entire books bashing their competition for this purpose (See: Peter Woit's "Not Even Wrong", which incidentally, is chuck full of so many inaccuracies someone else wrote a book disputing his book...) So when I see articles like these, I like to check out who the author is. Do they have a reason to write this piece? In this case, it's Adam Frank and Marcelo Gleiser. Both are coincidentally astrophysicists at very respected universities. I wonder what they're working on? It appears Marcelo Gleiser, one of the authors, just published an anti-String theory book which claims that "We don't need a Theory of Everything".

DennisP 11y ago
Yes, but it's possible that the points they raised were the reason they took that side of the debate. I don't think it's really useful to question people's motives, rather than just considering their arguments.
- protomyth 11y ago
  "I don't think it's really useful to question people's motives, rather than just considering their arguments." In an ideal world the argument should stand alone, but I find people's motives to be worth considering. Not for the usual you'll find in the media like looking for the corrupt or using those motives to dismiss their arguments. I find how people come to their beliefs to be really interesting. I can learn from the path they took even if I find the result to be broken. The danger is admiring the path and supporting the broken argument. As to the politics. Two people interacting means that you will have politics. Humans have conflicts from the battlefield to the soapbox to the pulpit to the lecture hall.

jordanpg 11y ago

This article strikes me as having lost its focus in editing somehow. One can hardly blame theoretical physicists for exploring above and beyond what the experimentalists are doing. It's not like there's a large body of more practical, down-to-earth problems being ignored in favor of these sexier, Nobel-bait questions. I believe the point is that we are in trouble if something exciting doesn't happen at LHC; in this case, getting the planet to fund an O($1T) accelerator to probe higher energy levels seems far-fetched. Theorists know this. This is a closely related point to the comment about the politics of theory. I don't know that this automatically spells crisis. There are plenty of problems out there that require the mathematical talent of folks that can perform at this level. Eventually, when more data is available, the pendulum will swing back towards interesting theory. After all, it's not the case that if there isn't some rush to a GUT before 2020, the human race loses.

nn3 11y ago
Modern physics currently cannot explain what most of the universe is made of, as in the dark matter problem. While not exactly "down to earth" this would seem like a very pressing problem to me, that may be in need of more attention.
- jordanpg 11y ago
  While I am as convinced as you about the urgency of these issues in the context of physics itself, a crisis it is not. Not for physicists and certainly not for civilians.
  - aminorex 11y ago
    You say that now, but when your sailboat gets eaten by a dark matter kraken you will sing a different song.

coldcode 11y ago

I wonder if our understanding of the universe will ultimately exceed our ability to reason about it. Complexity can increase without bound but our brain's capacity to understand and model isn't increasing at all. Maybe we should find some way to make smarter physicists.

escherplex 11y ago
Very Zen. The failure to recognize the limitations of one's received cognitive instrumentation. And this instrumentation is empirically oriented so without empirical validation what have you got? And with emphasis placed on theories which are 'sufficiently elegant and explanatory' while setting aside the need for experimental confirmation merely sets the theorist up for 'The great tragedy of Science — the slaying of a beautiful hypothesis by an ugly fact' (Thomas Huxley)

javajosh 11y ago

This is very frustrating for those of us that see the rather large problem in front of us - our apparent total inability to move around the stars, and only feeble ability to move around our solar system. This caps the lifespan of humanity (and most of the life we know) at about 500k years at best. So, even if we succeed wildly at our environmental and social problems, we'll end up with a single beautiful world getting smashed to bits by a meteor, gamma burst, or other uncontrollable, unavoidable cosmic event. Physicists need to get their heads out of their political/philosophical asses and start earning their bread - which is nothing less than to justify our technological existence by discovering the knowledge that will help our species live longer. If not for this, I think we'd all be better off living on a planet of 200M people living in rural villages, leading simple lives that are as happy and fair and erudite as fate and culture allows.

drjesusphd 11y ago
Plenty of us are working on nuclear fusion, but funding keeps getting cut year after year. It's simply not as sexy and doesn't get as much attention as the cosmological kinds of questions.

Animats 11y ago

This is mostly a problem with string theory. Here's a popular version of a critique.[1] Smolin's 2006 "The trouble with physics" is a book-length critique of it. Peter Woit' s "Not Even Wrong: The Failure of String Theory & the Continuing Challenge to Unify the Laws of Physics" is even more critical. It's been a decade since that, and the experimental evidence for string theory remains nonexistent. As Fred Hoyle once wrote, "Science is prediction, not explanation". A theory with no experimental support cannot lead to usable technology, either. Fundamental physics is currently stuck. There's a lot of denial about this. There's a whole generation of string theory faculty in senior positions. That's the problem. [1] http://www.theguardian.com/science/2006/oct/08/research.highereducation http://www.theguardian.com/science/2006/oct/08/research.high...

TheOtherHobbes 11y ago
I know someone with a PhD in string theory. He eventually left the field - not just because it was (as he put it) "mostly bullshit", but because the popularity of the field was based on distortingly aggressive academic PR and self-promotion by rather too many researchers in the string theory community. The other problem for physics is that so much of the talent works on Wall St doing things that are - for all practical purposes - useless, if not counterproductive. So physics is stuck for two reasons, and won't start moving again until the culture changes enough to fix both problems. Given the declining (political) value of long-term theoretical research in academia, and the relative impossibility of doing an original PhD exploring ideas outside the mainstream, I'm not expecting change any time soon. This is beyond tragedy, because in terms of medium-term human survival, nothing is more important than new science.