Sabine Hossenfelder on the search for new particles

[DrClaude]

TL;DR Summary

In private, many physicists admit they do not believe the particles they are paid to search for exist – they do it because their colleagues are doing it.

https://www.theguardian.com/commentisfree/2022/sep/26/physics-particles-physicists

Note: Please read what she is talking about before commenting.

 

[pinball1970]

Summary: In private, many physicists admit they do not believe the particles they are paid to search for exist – they do it because their colleagues are doing it.

https://www.theguardian.com/commentisfree/2022/sep/26/physics-particles-physicists

Note: Please read what she is talking about before commenting.

She said pretty much the same thing when they were discussing upgrades to the LHC and plans/talk build bigger accelerators a few months ago.

As an outsider who is interested in physics what is difficult to gauge is how seriously you guys look at this? If at all?

Dramatic click bate titles on YT get views = Ads = money?

She has cited claims before the LHC was switched on, these look genuine (ruling in / out super symmetry for example)

She fell out of love the field? Sour grapes? Trying to make a name?

I do not know, I do not read /write the papers work in the community or go to the conferences.

I would be interested as I recently saw this - #5!

https://academicinfluence.com/rankings/people/women-scholars/physics

 

[Vanadium 50]

She's very quick to accuse those who disagree with her of dishonesty.

 

[pinball1970]

She's very quick to accuse those who disagree with her of dishonesty.

Fair enough. I'll stick to her pop Science vids.

 

[mfb]

We do search for new species in the Arctic and in caves, and we search for signs of life on Mars. Zoologists consider in advance how to best search for them - what types of species we are the most likely to discover where. I'm not a zoologist (neither is Hossenfelder), but I'm pretty sure a 12-legged purple spider is not on that list.
The same happens in particle physics. We don't know where we might find new particles, so we search everywhere we can, and we consider in advance how to best search for it.
The analogy makes no sense at all. Zoologists just have the benefit of having far more species they can discover.

All experiments looking for those particles have come back empty-handed

(Non)-survivorship bias. We found the W and Z bosons, the tau neutrino, the top quark and the Higgs boson since 1980. Why are these particles not in her list? Because it would ruin the idea of the article, of course. We found tetraquarks, we found pentaquarks, we found a lot of charmonium and bottomonium states that still need a theoretical explanation. We discovered neutrino mixing, we are now measuring the mixing parameters with increasing precision, and we should clarify the mass order in the next years.

Are people looking for a Higgs boson decaying to an invisible Z' boson (or whatever) convinced this proposed particle exists? No. But it might exist, and we really don't want to miss it in that case. A zoologist won't be sure to find a new species under one specific rock either, but if they want to find new insect species they'll turn over many rocks.

This is yet another baseless rant to get more publicity and money.

 

[Vanadium 50]

The same happens in particle physics.

You don't really believe that, do you? You're just saying that. Just ask Prof. Hossenfelder.

Talk about your non-falsifiable predictions!

 

[strangerep]

This is yet another baseless rant to get more publicity and money.

One could attach that same epitaph to much of the hype around string theory and supersymmetry.

This is also why I avoid (anti-)social media. Some of the rants (and threats) that have been directed at Sabine are just... vile.

Although I don't necessarily agree with everything she says, I'm impressed that she's still standing.

 

[vanhees71]

as well as "quantum gravity", but I rather don't comment on colleagues working in the neighbor building...

 

[martinbn]

Not to be cynical, but is all about money? Sort of "Don't fund their field, fund mine."

 

[malawi_glenn]

Does she have anything to back up those claims?

Like this one "Talk to particle physicists in private, and many of them will admit they do not actually believe those particles exist."

 

[Vanadium 50]

The best conspiracies leave no evidence.

 

[ohwilleke]

She is dead on correct. The volume of garbage new particle papers ambulance chasing every new experimental anomaly is absurd. A hypothesis generation approach that starts from actual well established actual problems with the SM and marginalizes whimsical efforts to create solutions chasing problems would be welcome.

For example, I would never recommend hiring anyone who wrote a paper trying to devise new physics to explain the anomalous W boson mass measurement by CDF, as dozens of grown adults with physics PhDs actually did.

At a minimum, such speculative papers should be expected to seriously engage with and rule out all plausible non-BSM explanations for anomalies as opposed to their proposed alternatives, if they mean to be taken seriously as scholars.

 

[strangerep]

The best conspiracies leave no evidence.

Do you have any evidence of that? Oh,.. wait,...

 

[kodama]

She is dead on correct. The volume of garbage new particle papers ambulance chasing every new experimental anomaly is absurd.

and what If a future new experimental anomaly is verified?

 

[malawi_glenn]

The volume of garbage new particle papers ambulance chasing every new experimental anomaly is absurd.

Do you have a count for how many those are and what percentage? And what about publications in peer review journals. Only reading the ArXiV can be missleading. I recall the OPERA experiment and superluminal neutrinos. The day after the "anomaly" was presented there were about 10 papers each day on ArXiV for three weeks trying to explain those with some more or less goofy models. But IIRC, none of those were peer-review published at any point.

Anomaly is also hard to define. What count as an anomaly and what counts as a signal. It is just a matter of statistics, 3sigma or 5sigma etc.

I think the "problem" with theorists trying to explain every little 2 sigma "anomaly" is overexaggerated since far far far from the majority of peer-review published papers in theoretical particle physics are on this "theme".

Another perspective https://physics.aps.org/articles/v13/79

 

[mitchell porter]

Let's consider the proposed particles that she lists in her article:

Since the 1980s, physicists have invented an entire particle zoo, whose inhabitants carry names like preons, sfermions, dyons, magnetic monopoles, simps, wimps, wimpzillas, axions, flaxions, erebons, accelerons, cornucopions, giant magnons, maximons, macros, wisps, fips, branons, skyrmions, chameleons, cuscutons, Planckons and sterile neutrinos, to mention just a few. We even had a (luckily short-lived) fad of “unparticles”.

All experiments looking for those particles have come back empty-handed...

This is a very mixed collection.

Giant magnons and skyrmions actually exist, as quasiparticles in condensed matter.

A preon is essentially any sub-quark particle. I think most lay people would consider this a quite reasonable concept, on the general principle that humanity has repeatedly discovered deeper layers of structure in matter.

A magnetic monopole would be a particle with "magnetic charge"; a dyon, any particle with both electric charge and magnetic charge. As concepts, these may also seem reasonable, given that we have electric fields and magnetic fields, and electrically charged particles that generated the electric fields.

Wimps are weakly interacting massive particles, a candidate for the dark matter that seems to have mass but doesn't otherwise do much; and wimpzillas, simps, wisps, and fips are all variations on this concept. Perhaps the names are not very dignified. But we could translate them as follows:

Wimp = dark matter particle that is massive but interacts weakly
Wimpzilla = dark matter particle that is extremely massive but interacts weakly
Simp = dark matter particle that is massive and interacts strongly
Wisp = dark matter particle that is light and interacts weakly
Fip = "feebly interacting particle" that may or may not be dark matter

My point is that these are all variations on the same hypothesis, "dark matter particle", with slightly different properties and parameter values.

A "macro" seems to be any larger-than-microscopic object that could constitute dark matter - it need not be a particle at all, and can even be made of ordinary matter, so long as it's dark.

Then we get to some concepts whose definition and motivation is a little more technical.

The axion was originally postulated to explain why the theta parameter of QCD is zero. Now it refers to a much broader class of possible particles whose exact definition is unclear to me, but which I suppose have a dynamics similar to the axion. Hossenfelder also mentions the "flaxion", which like all the variations on "WIMP", is still just an axion, but one that also does some other things (related to "flavor").

We know about three types of neutrino; a sterile neutrino would just be another one, one that didn't interact with any standard model forces.

Sfermions are supersymmetric partners of fermions. Not a very common word, compared to names of specific superpartners like squark, slepton, gravitino, and so on.

All those were a little technical, but still fairly common. Finally, we have a collection of rarer terms - erebon, acceleron, cornucopion, maximon, branon, chameleon, cuscuton, Planckon. (The unparticles are somewhere between "technical but common" and "rare", I guess.)

Anyway, what do we learn from this review? That the "undiscovered hypothetical particles" fall into some very different groupings. Some represent quite straightforward concepts ("sub-quark particle", "particle with magnetic charge", "dark matter particle"). Others represent concepts that are more esoteric, but popular with theorists, and which are considered well-motivated. Finally, we have concepts that represent highly specific scenarios that are only studied by a few people.

 

[neilparker62]

Summary: In private, many physicists admit they do not believe the particles they are paid to search for exist – they do it because their colleagues are doing it.

https://www.theguardian.com/commentisfree/2022/sep/26/physics-particles-physicists

Note: Please read what she is talking about before commenting.

Yes - I always thought a bosun was a member of the ship's crew but now I know better

 

[malawi_glenn]

https://arxiv.org/list/hep-ph/new
25 new papers today, 0 about "anomalies"

 

[pinball1970]

https://arxiv.org/list/hep-ph/new
25 new papers today, 0 about "anomalies"

One μ to rule them all? Paper number three?

 

[apostolosdt]

https://www.math.columbia.edu/~woit/wordpress/
I often follow Peter Woit's page. In the one cited above, he makes his own remarks about Hossenfelder's article.

 

[malawi_glenn]

One μ to rule them all? Paper number three?

its more towards cosmological and about a method how "dark sector" models can be detected. It is not about a 2sigma statistical anomaly

https://www.math.columbia.edu/~woit/wordpress/
I often follow Peter Woit's page. In the one cited above, he makes his own remarks about Hossenfelder's article.

"I think she’s going after a small group of stragglers, not the center of theoretical activity"
which is more or less what I wrote earlier here

 

[pinball1970]

its more towards cosmological and about a method how "dark sector" models can be detected. It is not about a 2sigma statistical anomaly

It was a Lord of the rings query, mu does not sound like “ring” so I thought there may be some other connection.

One of those physics in jokes that I never understand!

 

[andresB]

Not to be cynical, but is all about money? Sort of "Don't fund their field, fund mine."

Well, in that case it would be a valid concern. The distribution of money and grants (and postdocs) shapes the reseach that it's done.

Take string theory for example. A lot of people go to string theory because there is money (and postdocs and positions) involved, and the money keep flowing to string theory because there is already a lot of people working in the field. It is a vicious circle in a subfield of physics that has given zero experimental results.

 

[malawi_glenn]

It is a vicious circle in a subfield of physics that has given zero experimental results.

Same could be said about many fields in math and social sciences as well. Physics is like sex, it might give practial results but its not why we do it

 

[Astronuc]

https://www.math.columbia.edu/~woit/wordpress/
I often follow Peter Woit's page. In the one cited above, he makes his own remarks about Hossenfelder's article.

Woit's page links to another page by Hossenfelder
http://backreaction.blogspot.com/2022/09/ive-said-it-all-before-but-here-we-go.html

 

[.Scott]

Physicists are looking for their diamonds and she seems to want to fence off large plots of investigative territory that she rates as far too unpromising. If she was looking to improve the situation, she should have made more specific criteria for how she would rate "promising" vs. "unpromising" - and leave it available for the consideration of those who actually make those decisions.

I read this article before this thread was created - and didn't think it worth a PF discussion.

 

[vela]

If she was looking to improve the situation, she should have made more specific criteria for how she would rate "promising" vs. "unpromising" - and leave it available for the consideration of those who actually make those decisions.

I think she does in a way. Her argument echoes what Feynman noted decades ago: because of the success of the Standard Model, theory is driving experiment rather than the other way around. To her, all these hypothetical particles are largely a waste of time and money, theoretical particle physics is a dead field until a real new experimental result is discovered suggesting where and how to modify the Standard Model, and a dead field shouldn't be allocated so many resources. Woit noted in his blog post that the LHC ruled out "a lot of bad theory." Hossenfelder would argue those bad theories shouldn't have even been considered in the first place.

 

[ohwilleke]

Do you have a count for how many those are and what percentage?

I don't have an exact tally, but I read all of the HEP papers abstracts on arXiv every day and it is a very substantial percentage of HEP-PH and the amount of effort going into LHC tests of some of the more dubious ones at HEP-EX (with very consistent null results) is large enough that given the costs of a new collider, ruling out these kinds of theories going forward isn't a very strong physics argument for the investment.

New anomalies routinely produce hundreds of such papers over a few weeks with a long steady drip afterwards.

There is also an undue share of papers rehashing dubious BSM physics efforts that have been done many, many times before that add little to the pool of knowledge (e.g. slight variations on see-saw models and group theory unifications).

I also don't take Sabine's argument to be that new papers of these kinds should be banned entirely, so much as an argument that institutionally, physics should look for ways to discourage idle, unmotivated speculation, and ambulance chasing resort to BSM explanations before carefully considering more plausible alternatives.

For example, perhaps we should treat as minus points in the promotion and hiring process, proposals that pile on to existing work, or that propose BSM explanations for experimental results that are later promptly resolved with SM physics and experimental methodology issues. This would be preferrable to blindly letting the self-reinforcing popularity contest metric of citations drive those decisions to the extent that we do now.

Proposing new physics is all good and well when there is a "real problem" motivated by the evidence or it eventually pans out or there is no other good explanation proposed.

A nihilistic "all papers are created equal" approach based only on numbers of papers produced and cited, rather than on what the papers are actually saying, is easy. But disavowing the hard work of critically evaluating the quality of physics work done also creates incentives that misallocate our scarce supply of theoretical and experimental physics resources.

 

[vanhees71]

Well, there are also even more useless pseudo-problems "solved", among them the so-called "measurement problem" or other philosophical quibbles about the foundation of quantum mechanics. There's not even an open question to be answered from a physics point of view...

 

[malawi_glenn]

I don't have an exact tally, but I read all of the HEP papers abstracts on arXiv every day and it is a very substantial percentage of HEP-PH

I gave today as an example. 0 of 25.
Will do it for a week, just for fun.

perhaps we should treat as minus points in the promotion and hiring process,

Who are "we"?

 

[kodama]

Let's consider the proposed particles that she lists in her article:

This is a very mixed collection.

Giant magnons and skyrmions actually exist, as quasiparticles in condensed matter.

A preon is essentially any sub-quark particle. I think most lay people would consider this a quite reasonable concept, on the general principle that humanity has repeatedly discovered deeper layers of structure in matter.

A magnetic monopole would be a particle with "magnetic charge"; a dyon, any particle with both electric charge and magnetic charge. As concepts, these may also seem reasonable, given that we have electric fields and magnetic fields, and electrically charged particles that generated the electric fields.

Wimps are weakly interacting massive particles, a candidate for the dark matter that seems to have mass but doesn't otherwise do much; and wimpzillas, simps, wisps, and fips are all variations on this concept. Perhaps the names are not very dignified. But we could translate them as follows:

Wimp = dark matter particle that is massive but interacts weakly
Wimpzilla = dark matter particle that is extremely massive but interacts weakly
Simp = dark matter particle that is massive and interacts strongly
Wisp = dark matter particle that is light and interacts weakly
Fip = "feebly interacting particle" that may or may not be dark matter

My point is that these are all variations on the same hypothesis, "dark matter particle", with slightly different properties and parameter values.

A "macro" seems to be any larger-than-microscopic object that could constitute dark matter - it need not be a particle at all, and can even be made of ordinary matter, so long as it's dark.

Then we get to some concepts whose definition and motivation is a little more technical.

The axion was originally postulated to explain why the theta parameter of QCD is zero. Now it refers to a much broader class of possible particles whose exact definition is unclear to me, but which I suppose have a dynamics similar to the axion. Hossenfelder also mentions the "flaxion", which like all the variations on "WIMP", is still just an axion, but one that also does some other things (related to "flavor").

We know about three types of neutrino; a sterile neutrino would just be another one, one that didn't interact with any standard model forces.

Sfermions are supersymmetric partners of fermions. Not a very common word, compared to names of specific superpartners like squark, slepton, gravitino, and so on.

All those were a little technical, but still fairly common. Finally, we have a collection of rarer terms - erebon, acceleron, cornucopion, maximon, branon, chameleon, cuscuton, Planckon. (The unparticles are somewhere between "technical but common" and "rare", I guess.)

Anyway, what do we learn from this review? That the "undiscovered hypothetical particles" fall into some very different groupings. Some represent quite straightforward concepts ("sub-quark particle", "particle with magnetic charge", "dark matter particle"). Others represent concepts that are more esoteric, but popular with theorists, and which are considered well-motivated. Finally, we have concepts that represent highly specific scenarios that are only studied by a few people.

x17 and Z' is not on the list

 

[ohwilleke]

I gave today as an example. 0 of 25.
Will do it for a week, just for fun.

You missed at least one: https://arxiv.org/abs/2209.14882 (proposing a hypothetical new light Higgs boson in a new Higgs doublet to facilitate the possible existence of sub-GeV hypothetical DM particles in a thermal freeze out model of DM particle creation).

Who are "we"?

We is the collective community of physicists with power to govern how its institutions operate, i.e. the physics community.

 

[ohwilleke]

what about publications in peer review journals.

The problem is not mostly that scientists end up relying on a lot of published papers that don't add value. The problem is that physicists waste a lot of time studying dubious models that would be better spent elsewhere. This is a problem whether the papers get published or not. The time spent writing the papers and the time by others reading the papers (who waits until publication to read papers anymore?), and not the make up of what gets actually published, is what causes the harm.

If there was less of an incentive to work on ill-motivated BSM particles, this brain power and time and the related resources available to the physics community would be spent on other research that is more likely to be fruitful.

Also, most of the resources spent searching for hypothetical particles that have no real motivation to exist in the first place on the experimental side does end up producing published papers. ATLAS and CMS kick out a fair number of these "we looked for hypothetical particle X and there were no statistically significant deviations from the SM" papers every month.

 

[Vanadium 50]

We is the collective community of physicists with power to govern how its institutions operate, i.e. the physics community.

I think at least some of the people who put themselves in the "we" category might be better characterized as "they". Just sayin'.

 

[strangerep]

Physics is like sex, it might give practial results but its not why we do it

Spoiler

Unkind people might say (theoretical) physics more like wanking...

Spoiler

... and now I wait to see if this will get past Berkeman...