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| Colbert’s legendary quadruple facepalm. |
Needless to say, we have not seen signs of a mirror universe we are not building portals to parallel universes. And if we did, trust me, you wouldn’t hear about it from New Scientist. To first approximation it is safe to assume that whatever you read in New Scientist is either not new or not science, or both.
This story is a case of both, neither new nor science. It is really – once again – about hypothetical particles that physicists have invented just because. In this case it’s particles which are exact copies of the ones that we already know, except for their handedness. These mirror-particles* do not interact with the normal particles, which is supposedly why we haven’t measured them so far. (You find instructions for how to invent particles yourself in my book, Chapter 9 in the section “Laws Like Sausages”.)
The idea of mirror-particles has been around since at least the 1960s. It’s not particularly popular among physicists, because what little we know about dark matter tells us exactly that it does not behave the same way as normal matter. So, to make mirror dark matter fit the data, you have to invent some reason for why, in the end, it is not a mirror copy of normal matter.
And then there is the problem that if the mirror matter really doesn’t interact with our normal matter you cannot measure it. So, if you want to get an experimental search funded, you have to postulate that it does interact. Why? Because otherwise you can’t measure it. Sounds like circular reasoning? That’s what it is.
Now once you have postulated that the hypothetical particles may interact in a way that makes them measureable, then you can make an experiment and try to actually measure them. It is such an measurement that this story is about.
Concretely, it seems to be about the experiment laid out in this paper:
- New Search for Mirror Neutrons at HFIR
arXiv:1710.00767 [hep-ex]
Now, look, this is exactly the type of ill-motivated experiment that I complained about the other day. Can you do this experiment? Sure. Will it help you solve any of the open problems in the foundations of physics? Almost certainly not. Why not? Because we have no reason to think that these particular particles exist and interact with normal matter in just the way necessary to measure them.
It is not a coincidence that we see so many of these small scale experiments now because this is a strategic decision of the community. Indeed, you find this strategy quoted in the paper for justification: “The 2014 Report of the Particle Physics Project Prioritization Panel (P5) stressed the importance of considering “every feasible avenue,”” to look for new types of dark matter particle.
It adds to this that, some months ago, the Department of Energy announced a plan to provide $24 million for the development of new projects to study dark matter which will undoubtedly fuel physicists’ enthusiasm for thinking up even more new particles.
This, folks, is only the beginning.
I cannot stress enough how idiotic this so-called “strategy” is. You will see million after million vanish into searches for particles invented simply because you can look for them.
If you do not understand why I say this is insanity and not proper science, please read my article in which I explain that falsifiability is necessary but not sufficient to make a hypothesis scientific. This strategy is based on a basic misunderstanding of science philosophy. It is an institutionalized form of motivated reasoning, a mistake that will cost taxpayers tens of millions.
The only good thing about this strategy is that hopefully the media will soon get tired writing about each and every little lab’s search for non-existing particles.
* Not to be confused with supersymmetric partner particles. Different story entirely.
I received today a pop-science report
ReplyDeletehttps://www.nbcnews.com/mach/science/scientists-are-searching-mirror-universe-it-could-be-sitting-right-ncna1023206?cid=sm_npd_nn_tw_ma
That features the experiments by Broussard. This claims the experiment is done with spare equipment, so I suppose it is not that expensive. The cited motivation is on a time discrepancy between the time of decay for a free neutron and one in a magnetic bottle. Now if you were to ask me I would say this might have something to do with QED interaction with quarks. It seems to me this would have to do with flavor change or weak nuclear interactions and QED, which might involve physics not currently understood. At least this seems to be more minimal than assumptions about parallel universes.
There are portholes of sorts that permit you to look into other universes, or other regions of a single universe. They are black holes. The Penrose conformal diagram might be considered to be an entanglement between two black holes, this is what Lenny Susskind thinks, and if you enter the black hole the split horizon permits you to peer into the other world. There is a minor problem that you can't get out and in a pretty short finite time you reach a region with divergent Weyl curvature. Maybe more realistically a black hole has a distribution of states determined by an integer partition of states with many other black holes. I don't think the neutron and its anomalous decay rate has much to do with this.
I suppose the physics community is a Warhol 15 minutes of fame phase. There are so many people out there who command attention who are completely wrong. A big example is Wharton who erroneously thinks we can get around Bell's theorem with time reversed actions. There are plenty more.Broussard is maybe the latest, but at least she is doing some honest experimental work.
Lawrence,
DeleteYes, I also saw this. But it's not mentioned in the paper, so I'm not sure exactly what the relation is. I don't see how you need a whole mirror universe just to explain what's with the neutron.
There has been a storm of controversy about variability in the nuclear decay rates being affected by solar activity and the regular changing relationship between the sun and earth.
DeleteThis all goes back to 2006, when physicists at Purdue, Stanford and other places noticed something that at first defied physical explanation: Radioactive elements were changing their decay rates. This flew in the face of long-accepted physics theory, which held that these rates are constant. Radioactive decay apparently grew more pronounced in winter than in summer, and when scientists went looking for an explanation, they noticed this appeared to correlate with solar flares.
During that time, we learned from Purdue physicist Ephraim Fischbach that this kept happening. He noticed a change in the radioactive decay rate of a manganese isotope, and also tied it to a solar flare that happened a night before. So that meant something came out of the sun, went through the Earth, hit a piece of manganese-54 and changed the rate at which it decays into chromium-54, spewing out ionizing particles. This also happened to an isotope called chlorine-36, in different experiments at different labs. The unusual decay change has happened during 10 solar flares since 2006, and the song remains the same.
The consensus hypothesis to explain this decay rate variability was grounded on the effects of solar neutrinos on decay rates inspired by the simple fact that the sun produces boatloads of solar neutrinos.
I never liked this neutrino explanation mainly because neutrinos have little if any impact on anything that they come near. Instead, I believe this issue revolves around the common magnetic connection that exists between the sun and the earth. Solar flares are produced by massive magnetic fluxuations in the sun’s corona especially just before the eruption of a coronal flare. Furthermore, the increase activity in the solar wind also wreaks havoc with the earth’s magnetic fields.
Zooming into deeper speculation about basic causation, the fluctuations in the ambient magnetic environment could change the nature of the vacuum which supplies virtual particles to enable and fundamental action of the nuclear decay process. Since the concept of vacuum fluctuations arises in Quantum Field Theory (QFT), in connection to the zero-point energy of the electromagnetic field, magnetic perturbations in the ambient magnetic environment could vary the probability of how readily W and Z particles are formed from the vacuum.
This hypothesis fits nicely into this magnetic connection to the variability of the decay rate of the neutron.
"A big example is Wharton who erroneously thinks we can get around Bell's theorem"
DeletePhysics is not the catechism of a fundamentalist religion.
@Axil: the case for variability in the nuclear decay rates being affected by solar activity is weak.
Delete"The instabilities in the radon measurements at the Geological Survey of Israel [reported by Fischbach and collaborators] are obviously related with solar irradiance and rainfall and cannot be ascribed to neutrinos. Besides sensitivity of the electronics, free movement of radon gas inside the tank along temperature gradients is the most likely mechanism behind the diurnal and seasonal decay rate changes in the small gas volumes monitored by the detectors.
The observation of “neutrino-induced decay” appears to be an illusion fed by confirmation bias. The experiment has not been conducted with sufficient care to eliminate environmental influences and counter-evidence has been systematically ignored to maintain the claim of new physical discoveries. The evidence does not suggest that radioactive decay is triggered by neutrinos. The subsequently emitted radiation is not aligned with neutrino flux. There are no cyclic deviations from the exponential decay law. Ensuing inference about solar dynamics is unfounded."
From "Solar influence on radon decay rates: irradiance or neutrinos?"
S. Pommé, Published in Eur.Phys.J. C79 (2019) no.1, 73
Thanks, I fixed that!
ReplyDeleteIf an as of yet unidentified quantum mechanical based process make matter and/or energy disappear from within a totally enclosed space without a trace through a macro type of quantum superposition, say from inside and totally enclosed by diamond or quartz, would that matter and/or energy be a candidate for consideration as dark matter?
ReplyDeleteI agree with most of the content, and the headlines are definitely far too sensationalized, but your evaluation is too harsh for a number of reasons.
ReplyDelete- There really are known anomalies that mirror matter could help explain, such as in neutron lifetime measurements. Mirror matter isn't just postulated for no reason.
- The experiment is extremely low cost: it doesn't even require building anything new, but rather just uses a little beam time from an existing experiment.
- Even if mirror matter weren't an idea, and there weren't existing anomalies with neutrons, it is still interesting to measure them because they are one of only ~4 common particles in the universe that are stable for at least a few seconds. This isn't exactly a Rube Goldburg machine they're using here. These are some of the simplest ingredients you can get, anywhere.
- Constraints from such exploratory experiments have a way of ruling out theories later that weren't even dreamt of at the time the experiment was run, which helps narrow down the pool. Other examples would be photon masses, Lorentz violation, or equivalence principle violation. You could say they'll "almost certainly" find nothing, because such theoretical possibilities just sound unlikely, but that same attitude would have kept us from discovering parity violation, which is equally "obviously" impossible. If experimentalists find they can do something new, quickly and cheaply, they should go ahead! If such experiments are not done, it costs more in the long run, since a lot of new theories will begin completely unconstrained.
- Depending on your personal sense of aesthetics, mirror matter could be one of the simplest possible theories you could write down. After all, it uses the simplest possible symmetry, a Z_2 "X is the same as Y". Others could say that mirror matter actually makes the Standard Model simpler, because it takes equally as long to specify but gets rid of the parity violation. Now, you could say that mirror symmetry is contrived because this symmetry results in a lot of new particles, and there's too much freedom in how you can break it. But this is _also_ an aesthetic judgment. There just isn't a neutral objective stance one can take on theory evaluation. If we actually had a crystal ball saying which theories were good and which weren't, physics would be easy.
- Most physicists already agree with your judgment of mirror matter, which is why not that many people work on it. But I still think it's a good idea for _somebody_ to work on it, and that results naturally if people differ in their judgment and taste. Because of this, I find it difficult to be upset that an experiment like this is happening!
I am not "upset" that the experiment is happening.
Delete"Now, you could say that mirror symmetry is contrived because this symmetry results in a lot of new particles, and there's too much freedom in how you can break it. But this is _also_ an aesthetic judgment. There just isn't a neutral objective stance one can take on theory evaluation."
Yes there is. Do what worked in the past. Arguments from beauty have not historically been correlated with success.
Doing what worked in the past is also ambiguous.
DeleteBuilding ever larger and larger colliders worked great in the past. Model building by trying to fit meson and baryon masses into a "beautiful" framework worked great too (in the sense that, of course, 99% of attempts were wrong, but one of them gave us quarks). A lot of great experiments in the early 20th century just consisted of putting a cloud chamber or a phosphor next to some random stuff and just seeing what happened, without any theoretical reason to expect anything at all. A lot of great early 20th century theorists preached the value of beauty in theory until their deaths.
I suspect anybody who knows enough history can use it to argue for, or against, any theory whatsoever. There isn't a single clean lesson here.
Does the discrete P symmetry require a mirror universe? The weak interactions are funny with parity or chirality, in that such interactions violate this symmetry. The parity is left handed. The decay of a neutron is n → p + e^+ + ν_e, which on the quark level is d → u + e^+ + ν_e. The weak interaction transformed the flavor of the quarks and produced the positron and neutrino with zero net lepton number. The neutrinos are always left handed. The motivation for this idea is that neutrons the fly freely and those in a magnetic bottle seem to exhibit different decay rates. That is a bit of a head scratcher, and the data does seem to be drifting in this direction. The d-quark with charge ⅓e transforms into an u-quark with ⅔e. The d-quark has 4.8MeV mass and the u-quark about half of that. So in terms of energy this looks right, but the slow flavor changing interaction can be thought of as a tunneling barrier that must be overcome. So is the presence of a magnetic field in bottling up the neutrons presenting additional energy to this barrier to the decay? To answer this, at least theoretically, would seem to entail some QED and IR low energy weak interaction physics.
DeleteThe idea of the mirror universe is there is a world with left handed chirality and another with right handed. This is a much bigger proposal than what I outline above. There is maybe nothing impossible about a particle in this world fluctuating between this an a mirror world, so its occurrence in a sense toggles. However, this is a very speculative proposal, far more than what I sketch above.
Ms. Hossenfelder has a tweet here on the simulation hypothesis. This is the idea our universe is some computer coded simulation. Now this matrix idea is almost infinitely speculative, and it is borders on religion with the programmer of this world being synonymous with a god. Yet some big name people are taking this seriously, such as Neil deGrasse-Tyson. Though he does not perform as a scientist that much any more he is a big exponent for science. I regard the whole idea as virtually preposterous, and its popularity seems to reflect the old Twilight Zone episode, The Monsters are Due on Maple Street, where a kid sounds off on a lot of wacky stuff that gets people wound up. We seem to be in a time where the most extreme speculation is most likely to get journalistic attention.
Kevin,
DeleteYou are not following. Building colliders has worked in the past because there were good reasons to think particles were to find, and also the costs were not prohibitive. This is no longer the case.
And saying that beautiful ideas sometimes work does not mean that they are good guides. Placebos also sometimes "work" in the sense that people happen to get better after taking them. If you look at the history of physics you will notice that there is no correlation between the beauty of an idea and its success. Therefore, one should not rely on beauty the same way one should not try to infer causal relations by only looking at instances that confirm your hypothesis.
There is, however, a very strong correlation between arguments from consistency and breakthroughs.
"I suspect anybody who knows enough history can use it to argue for, or against, any theory whatsoever. There isn't a single clean lesson here."
If you find anything wrong with my argument, please explain what. You seem to be discarding it merely because you do not like the conclusions.
Hi SABINE, !!!
ReplyDeleteThanks for that.
-. I Really needed a laugh.
Thank You.
You bring to mind
something I read
not too long ago.
-the origin of which escapes me.
( I'm glad for that )
It had to do with the idea
of 'minni' black holes
cropping up all over
this planet.
Ok. ( in reading) I'll bite)
They then went on to postulate
that you could create one
in your kitchen...
I shouldn't have to tell you
the first thought in my head
that translated to language
was
Oh, Really ?
Now, I consider myself
extremely open minded.
( possibility over probability)
Even So .
I couldn't imagine
a fantastic, hypothetical
practicality to this notion.
except,. oh, wait...
If,after a party,
you find yourself standing
in your kitchen staring
at a mess. ..
( sink full of dishes,
garbage that needs to be taken
out,etc.)
And you feel a bit tired
for the task...
That's It !
Minni Black Holes.,.!!!!
Why didn't I think of that.
Damn.
- I won't tell you how long
I laughed about this .
it might shame me. lol
Thanks again,Sabine
You made my day.!
Love Your Work.
I am an outsider to the details of this debate but I am moved to
ReplyDeletecomment by your emphatic repetition of the idea that falisifiability is necessary for a hypothesis to be truly scientific. I wrote to you in detail about this. A hypothesis may be verifiable without being falisifiable - it may even be verifiable by experimental test. The current search for magnetic monopols is an example [courtesy of Roger Penrose in The Road to Reality where he rightly rejects falsifiability an a necessary condition]. That search may end in finding one, in which case the hypothesis that they exist will be verified, or it may continue forever not finding one in which case we will not know whether they exist and we have not found them or they do not exist. And that search is certainly acceptable science.
As I understand it a parallel universe would be in contact with our universe in infinity. So what is the use of opening a portal in the first place?
ReplyDeleteHey Marten,
DeleteApologies for a late reply.In answer to your question, I hate to come off as a cynic...
However, using history and human nature as our guide, two uses ( off the top of my head).
1.) Exploration
to pillage, and exploit resources.
and ( that being done)
2.) A place to put
our garbage, trash
- and people we don't
like anymore lol.
Oh, and yeah;
I could see a couple of wars. down the road.
All the best,
Is it just a coincidence that this story drop simultaneously with the Netflix premiere of Stranger Things 3? The one sci-fi show out there with just a single parallel world (no multiverse afaik) full of mischief?
ReplyDeleteThere have been some famous high-profile bets in science. Why not bet a substantial sum that no particle dark matter will be detected in, say, the next 10 years. No risk to you, because you are confident that no experiment will turn up anything. That means that you get to pocket a substantial sum in time for retirement. Sure, most scientists wouldn't be able to put up that much, but a group of them could. By putting their money where their mouths are, if 100 people, say, pledge EUR 500 each, then that's 50,000 for you.
ReplyDeletePhillip Helbig: When did science become pugilism?
ReplyDeleteWhat exactly is the scientific argument behind betting money you are right? How does that improve your logic or your argument?
It doesn't, and it isn't science, personal conviction has nothing to do with science. There are millions of deluded people in the world willing to bet their lives (and their children's lives) on all sorts of supernatural hokum, do you find their arguments more compelling for that?
Science is not won by assertion, or bets, or fist fights, or by pounding on the podium, or by waving the flag of some country.
When people run out of cogent arguments, they either admit they are wrong, or they resort to emotional arguments, insults and other forms of ad hominem attack (like 'put your money where your mouth is'), and ultimately threats of violence and actual violence. The latter happens when they don't have any rational reason to believe in something, they are emotionally committed to the belief and were just pretending it was rational. Exposing their irrationality reverts them to emotional defenses, including yours above.
I presume you have run out of cogent arguments.