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I feel like this was too much a diatribe on why supersymmetry is not a good solution and didn't spend enough time on evaluating what the actual implications are

I feel like this was too much a diatribe on why supersymmetry is not a good solution and didn't spend enough time on evaluating what the actual implications are of this result holding.

mannykannot 4y ago
On the one hand, it does not strike me as unreasonable to point out that experience suggests that this, too, will turn out to be an experimental or methodological error. Nor do I think it is unreasonable to point out that this result, if correct, would not validate supersymmetry (if that is, in fact, the case.) On the other hand, the fact that supersymmetry isn’t a theory, but a property of a class of models that can be tweaked to fit a broad range of experimental results (again, if that is, in fact, the case) does not rule out the possibility that the LHC could have found evidence that strongly supported one specific theory that happens to be supersymmetric. Hossenfelder seems to be saying that the LHC definitively ruled out what was considered to be the most plausible candidate(s), which would imply there was at least one such falsifiable theory. Allegations of incompetence or mendacity should not be made lightly, and unless the promoters of the LHC routinely said supersymmetry in general might be disproved, the allegations seem unwarranted.
- lisper 4y ago
  Falsifying supersymmetry is like falsifying Ptolemaic epicycles. You can never falsify it with data because epicycles can always be constructed to fit any data set [1]. Likewise, a sypersymmetric theory can be constructed to fit any set of parameters. But fitting the data is not enough. You have to fit the data with substantially fewer parameters than data points. That's the challenge. [1] https://www.youtube.com/watch?v=qS4H6PEcCCA https://www.youtube.com/watch?v=qS4H6PEcCCA
  - mannykannot 4y ago
    Indeed. Are you suggesting, perhaps, that the promoters of the LHC were making claims that they knew could not be satisfied by it - or, perhaps, that nothing they said could reasonably be interpreted as such a claim? The trouble is, I don't know which specific claims Hossenfelder is basing her allegations on.
    - robonerd 4y ago
      She explains that here http://backreaction.blogspot.com/2018/03/the-multiworse-is-coming.html http://backreaction.blogspot.com/2018/03/the-multiworse-is-c... Quote: Before the LHC’s launch in 2008, many theorists expressed themselves confident the collider would produce new particles besides the Higgs boson. That hasn’t happened. And the public isn’t remotely as dumb as many academics wish. They’ll remember next time we come ask for money. The big proclamations came almost exclusively from theoretical physicists; CERN didn’t promise anything they didn’t deliver. That is an important distinction, but I am afraid in the public perception the subtler differences won’t matter. It’s “physicists said.” And what physicists said was wrong. Like hair, trust is hard to split. And like hair, trust is easier to lose than to grow. What the particle physicists got wrong was an argument based on a mathematical criterion called “naturalness”. If the laws of nature were “natural” according to this definition, then the LHC should have seen something besides the Higgs. The data analysis isn’t yet completed, but at this point it seems unlikely something more than statistical anomalies will show up. I must have sat through hundreds of seminars in which naturalness arguments were repeated. Let me just flash you a representative slide from a 2007 talk by Michelangelo L. Mangano (full pdf here), so you get the idea. The punchline is at the very top: “new particles must appear” in an energy range of about a TeV (ie accessible at the LHC) “to avoid finetuning.” I don’t mean to pick on Mangano in particular; his slides are just the first example that Google brought up. This was the argument why the LHC should see something new: To avoid finetuning and to preserve naturalness. I explained many times previously why the conclusions based on naturalness were not predictions, but merely pleas for the laws of nature to be pretty. Luckily I no longer have to repeat these warnings, because the data agree that naturalness isn’t a good argument.
      - mannykannot 4y ago
        Thanks for this information. I agree with Dr. Hossenfelder about naturalness, but personally, I don't think that (or anything else here) justifies saying, about those who promoted the LHC with their expectations, that they were "either incompetent or lying or both." Irresponsible? maybe, depending on how influential their position was and how forcefully they made the claim.
  - ravi-delia 4y ago
    I feel like that example assumes the conclusion. A better analogy would be "spinning objects theories". It's a category so broad you could always find something which works, but since it's not really thought of as a particular solution, it isn't so vulnerable to overfitting. Epicycles were bad largely because they gave a false impression of closing in on reality; every new round of additions consisted of smaller and smaller tweaks. Spinning object theories are even more broad and adaptable, but since they aren't basically one solution you don't have the same issue. When Kepler found a spinning object theory which worked, it wasn't overfitting.
    - lisper 4y ago
      What on earth is a "spinning object theory"???
      - ravi-delia 4y ago
        Planets and sun in epicycles around the earth, planets and moons in cycles around the sun, planets in cycles around the sun and moons in cycles around planets, that sort of thing. I used it as an example because "supersymmetry" is more a descriptor, than a theory unto itself. If you make your "theory" big enough it's going to technically be unfalsifiable, but that's more because you drew too large a bound than any mark against it.
        lisper 4y ago
        Ah. OK, in that case... > When Kepler found a spinning object theory which worked, it wasn't overfitting. Well, yeah, that's true, but the important thing about Kepler was not the fact that it was a "spinning object theory", it was the switch from a "circular theory" to an "elliptical theory". (Also the switch from geocentrism to heliocentrism, but that was Copernicus, not Kepler). This is the sort of thing that the supersymmetrists are hoping to achieve, but have not yet achieved, most likely because nature is not supersymmetric in point of actual fact.
gus_massa 4y ago
The problem is that (if confirmed) no one has any clue about how to fix the Standard Model to fix this. It will be a small fix, not a total rewrite like other alarmist articles claim. Anyway, no one know how exactly will be the fix. So each one propose her/his own pet theory. Supersymmetry? A second Higgs boson? Other ...???? She doesn't like supersymmetry, and rants too much about the people that guess the fix will use supersymmetry. (I like supersymmetry, but this is not my research area, so she knows much more about this than me about this.)

I feel like this was too much a diatribe on why supersymmetry is not a good solution and didn't spend enough time on evaluating what the actual implications are of this result holding.

mannykannot 4y ago

On the one hand, it does not strike me as unreasonable to point out that experience suggests that this, too, will turn out to be an experimental or methodological error. Nor do I think it is unreasonable to point out that this result, if correct, would not validate supersymmetry (if that is, in fact, the case.) On the other hand, the fact that supersymmetry isn’t a theory, but a property of a class of models that can be tweaked to fit a broad range of experimental results (again, if that is, in fact, the case) does not rule out the possibility that the LHC could have found evidence that strongly supported one specific theory that happens to be supersymmetric. Hossenfelder seems to be saying that the LHC definitively ruled out what was considered to be the most plausible candidate(s), which would imply there was at least one such falsifiable theory. Allegations of incompetence or mendacity should not be made lightly, and unless the promoters of the LHC routinely said supersymmetry in general might be disproved, the allegations seem unwarranted.

lisper 4y ago
Falsifying supersymmetry is like falsifying Ptolemaic epicycles. You can never falsify it with data because epicycles can always be constructed to fit any data set [1]. Likewise, a sypersymmetric theory can be constructed to fit any set of parameters. But fitting the data is not enough. You have to fit the data with substantially fewer parameters than data points. That's the challenge. [1] https://www.youtube.com/watch?v=qS4H6PEcCCA https://www.youtube.com/watch?v=qS4H6PEcCCA
- mannykannot 4y ago
  Indeed. Are you suggesting, perhaps, that the promoters of the LHC were making claims that they knew could not be satisfied by it - or, perhaps, that nothing they said could reasonably be interpreted as such a claim? The trouble is, I don't know which specific claims Hossenfelder is basing her allegations on.
  - robonerd 4y ago
    She explains that here http://backreaction.blogspot.com/2018/03/the-multiworse-is-coming.html http://backreaction.blogspot.com/2018/03/the-multiworse-is-c... Quote: Before the LHC’s launch in 2008, many theorists expressed themselves confident the collider would produce new particles besides the Higgs boson. That hasn’t happened. And the public isn’t remotely as dumb as many academics wish. They’ll remember next time we come ask for money. The big proclamations came almost exclusively from theoretical physicists; CERN didn’t promise anything they didn’t deliver. That is an important distinction, but I am afraid in the public perception the subtler differences won’t matter. It’s “physicists said.” And what physicists said was wrong. Like hair, trust is hard to split. And like hair, trust is easier to lose than to grow. What the particle physicists got wrong was an argument based on a mathematical criterion called “naturalness”. If the laws of nature were “natural” according to this definition, then the LHC should have seen something besides the Higgs. The data analysis isn’t yet completed, but at this point it seems unlikely something more than statistical anomalies will show up. I must have sat through hundreds of seminars in which naturalness arguments were repeated. Let me just flash you a representative slide from a 2007 talk by Michelangelo L. Mangano (full pdf here), so you get the idea. The punchline is at the very top: “new particles must appear” in an energy range of about a TeV (ie accessible at the LHC) “to avoid finetuning.” I don’t mean to pick on Mangano in particular; his slides are just the first example that Google brought up. This was the argument why the LHC should see something new: To avoid finetuning and to preserve naturalness. I explained many times previously why the conclusions based on naturalness were not predictions, but merely pleas for the laws of nature to be pretty. Luckily I no longer have to repeat these warnings, because the data agree that naturalness isn’t a good argument.
    - mannykannot 4y ago
      Thanks for this information. I agree with Dr. Hossenfelder about naturalness, but personally, I don't think that (or anything else here) justifies saying, about those who promoted the LHC with their expectations, that they were "either incompetent or lying or both." Irresponsible? maybe, depending on how influential their position was and how forcefully they made the claim.
- ravi-delia 4y ago
  I feel like that example assumes the conclusion. A better analogy would be "spinning objects theories". It's a category so broad you could always find something which works, but since it's not really thought of as a particular solution, it isn't so vulnerable to overfitting. Epicycles were bad largely because they gave a false impression of closing in on reality; every new round of additions consisted of smaller and smaller tweaks. Spinning object theories are even more broad and adaptable, but since they aren't basically one solution you don't have the same issue. When Kepler found a spinning object theory which worked, it wasn't overfitting.
  - lisper 4y ago
    What on earth is a "spinning object theory"???
    - ravi-delia 4y ago
      Planets and sun in epicycles around the earth, planets and moons in cycles around the sun, planets in cycles around the sun and moons in cycles around planets, that sort of thing. I used it as an example because "supersymmetry" is more a descriptor, than a theory unto itself. If you make your "theory" big enough it's going to technically be unfalsifiable, but that's more because you drew too large a bound than any mark against it.
      - lisper 4y ago
        Ah. OK, in that case... > When Kepler found a spinning object theory which worked, it wasn't overfitting. Well, yeah, that's true, but the important thing about Kepler was not the fact that it was a "spinning object theory", it was the switch from a "circular theory" to an "elliptical theory". (Also the switch from geocentrism to heliocentrism, but that was Copernicus, not Kepler). This is the sort of thing that the supersymmetrists are hoping to achieve, but have not yet achieved, most likely because nature is not supersymmetric in point of actual fact.

gus_massa 4y ago

The problem is that (if confirmed) no one has any clue about how to fix the Standard Model to fix this. It will be a small fix, not a total rewrite like other alarmist articles claim. Anyway, no one know how exactly will be the fix. So each one propose her/his own pet theory. Supersymmetry? A second Higgs boson? Other ...???? She doesn't like supersymmetry, and rants too much about the people that guess the fix will use supersymmetry. (I like supersymmetry, but this is not my research area, so she knows much more about this than me about this.)