Around about 1978, cosmologists (the scientists who study the universe as a whole) were puzzled by a problem of fine-tuning. They had figured out that the expansion rate of the very early universe (at the time of the Big Bang) seems to have been incredibly fine-tuned, apparently to about one part in ten to the sixtieth power. This dilemma was known as the flatness problem.
Around 1980 Alan Guth (an MIT professor) proposed a way to solve the flatness problem. Guth proposed that for a tiny fraction of its first second (for less than a trillionth of a trillionth of a second), the universe expanded at an exponential rate. The universe is not expanding at any such rate, but Guth proposed that after a very brief instant of exponential expansion, the universe switched back to the normal, linear expansion that it now has. The theory was devised to get rid of some fine-tuning, but it turned out that the theory required fine-tuning of its own in multiple places. So we had a kind of "rob Peter to pay Paul" situation in which it was unclear that the need for fine-tuning had been reduced. A recent paper says this: "It actually requires much
more fine-tuning for the Universe to have inflated than for it
to have been placed in some low-entropy initial state (Carroll
& Chen 2004)." The paper also refers to "the highly fine-tuned initial conditions required
for inflation to work."
There was never any observational evidence for the idea of primordial exponential expansion (typically called the cosmic inflation theory), and the idea was very far-fetched from the beginning, depending on the existence of a never-observed "inflaton field." But despite such flaws, Guth's idea became very popular among the small tribe of cosmologists. Between 1980 and 2020 the Guth-following cosmologists spent decades cranking out many hundreds of different versions of the cosmic inflation theory, which appeared in thousands of different speculative physics papers. It's actually a big sign of weakness when theorists have to keep grinding out countless different versions of a theory. Good theories usually don't have to go through hundreds of iterations.
It is now the year 2022, and there is still no evidence for the theory of cosmic inflation. Supporters of the theory sometimes claim that the theory predicts this or that which has been observed. The fact that a theory may predict something that was observed does nothing to show that the theory is correct. Many false theories predict (without any great precision) something that was actually observed. A theory is only supported by successful predictions if the theory uniquely predicts something correctly (being the only theory predicting that thing) or correctly predicts things with high numerical precision (such as when a gravitational theory correctly predicts that some asteroid will crash into Jupiter in exactly 32 days, 7 hours and 23 minutes).
For many decades cosmologists have been lost in a strange little world of fantasy whenever they dealt with this cosmic inflation theory. As different versions of the theory have kept failing, cosmologists have kept producing new versions of the theory; and by now there are many hundreds of versions of it, making predictions all over the map. All attempts to provide some empirical support for cosmic inflation theory have failed.
The main prediction of cosmic inflation theories have been that there would be observed something called primordial gravitational waves, gravitational waves coming from the very early history of the universe. Although non-primordial gravitational waves have been detected (arising from times when the universe was already billions of years old), nothing has come from searches for primordial gravitational waves, which have gone on for years with ever-more-fancy and ever-more-expensive equipment. A 2019 article states, "Models such as natural and quadratic inflation that were popular several years ago no longer seem tenable, says theorist Marc Kamionkowski of Johns Hopkins University." A late 2021 article (based on this paper) is entitled "Primordial Gravitational Waves Continue to Elude Astronomers." But rather than discarding a theoretical approach that isn't working, our cosmologists keep tying themselves into knots by spinning out more and more speculative ornate versions of the theory (which already has many hundreds of different versions). This has all been a giant waste of time, without any real success.
It is interesting that when scientists release papers telling us that they still can't find any sign of something they have long been looking for, something predicted by some theory they cherish, the scientists often use paper titles that don't mention any failure, and try to give their observational failure some kind of positive sound. The latest big paper announcing that nothing has been found in the search for primordial gravitational waves has a title mentioning "improved constraints on primordial gravitational waves," and the "improved" makes it sound like something positive has happened, although the observational result is purely negative.
Another "high priest of speculation" professor comparable to Guth is Edward Witten of Princeton. For many years Witten was a leading champion of the empirically unsuccessful theories called supersymmetry and string theory. They are both wildly speculative theores that have no observations supporting them.
Like the cosmic inflation theory, the supersymmetry theory arose as a speculative attempt to explain away (or kind of sweep under the rug) a case of cosmic fine-tuning that bothered scientists. The issue of the fine-tuning of the Higgs mass (the mass of the Higgs boson) was skillfully explained by physicist Ben Allanach in a previous article at the Aeon site:
"Behind the question of mass, an even bigger and uglier problem was lurking in the background of the Standard Model: why is the Higgs boson so light? In experiments it weighed in at 125 times the mass of a proton. But calculations using the theory implied that it should be much bigger – roughly ten million billion times bigger, in fact....Quantum fluctuations of ultra-heavy particle pairs should have a profound effect on the Higgs boson, whose mass is very sensitive to them....One logical option is that nature has chosen the initial value of the Higgs boson mass to precisely offset these quantum fluctuations, to an accuracy of one in 1016. However, that possibility seems remote at best, because the initial value and the quantum fluctuation have nothing to do with each other. It would be akin to dropping a sharp pencil onto a table and having it land exactly upright, balanced on its point. In physics terms, the configuration of the pencil is unnatural or fine-tuned. Just as the movement of air or tiny vibrations should make the pencil fall over, the mass of the Higgs shouldn’t be so perfectly calibrated that it has the ability to cancel out quantum fluctuations. However, instead of an uncanny correspondence, maybe the naturalness problem with the Higgs boson could be explained away by a new, more foundational theory: supersymmetry."
In an article in Symmetry magazine, we have a similar explanation:
"To understand what’s fishy about the observable Higgs mass being so low, first you must know that it is actually the sum of two inputs: the bare Higgs mass (which we don’t know) plus contributions from all the other Standard Model particles, contributions collectively known as “quantum corrections.” The second number in the equation is an enormous negative, coming in around minus 1018 GeV. Compared to that, the result of the equation, 125 GeV, is extremely small, close to zero. That means the first number, the bare Higgs mass, must be almost the opposite, to so nearly cancel it out. To some physicists, this is an unacceptably strange coincidence."
How big a coincidence? The Symmetry article later quotes physicist Lawrence Lee Jr. as saying “the conundrum with the Higgs mass, which would require fine-tuning on the order of 1-in-1034,” which is a coincidence like the coincidence of you correctly guessing the full phone numbers of three consecutive strangers.
Scientists should have just accepted this case of very precise fine-tuning in nature. But instead, many of them made a long, quixotic, futile attempt to overthrow it (like someone trying to overthrow the observation that the sun is hot, with some elaborate theory trying to explain how the sun isn't really hot). Why did they do that? Because they had a motivation, an ideological motivation rather than the motivation of simply discovering truth. Their ideological motivation was related to a belief that the universe should not be anything that looked like a product of design. This ideological motivation is clearly stated in the Symmetry article by physicist Lee, who states it as follows: “In general, what we want from our theories—and in some way, our universe—is that nothing seems too contrived.” If you want for the universe to not "seem too contrived," then you may twist yourself into knots trying to explain away cases of apparent fine-tuning in the universe.
An article this year makes it rather clear that the supersymmetry theory was mainly motivated by a desire to get rid of a case of fine-tuning, and make the universe look like it was a little less lucky, a little less providentially blessed. We read this:
"For example, the small mass of the Higgs boson is notoriously difficult to explain—its calculation requires subtracting two very large numbers that just happen to be slightly different from each other. 'But if you add supersymmetry, this takes care of all these cancellations such that you can get a light Higgs mass without needing to have such luck,' says Elodie Resseguie, a postdoc at the US Department of Energy’s Lawrence Berkeley National Laboratory."
Like the cosmic inflation theory originated by Guth, the supersymmetry theory championed by Witten was a case of "twist yourself into knots trying to explain away a case of apparent fine-tuning in the universe." It advanced elaborate speculations about undiscovered "superpartner" particles that might help sweep under the rug the fine-tuning involving the Higgs mass or Higgs boson. Just as the cosmic inflation theory has failed all empirical tests (with its predicted primordial gravitational waves never being found), the supersymmetry theory has failed all tests. It was hoped that the Large Hadron Collider would find evidence of these "superpartner" particles predicted by supersymmetry theory, but it has found no such thing.
Just as there is no evidence for the supersymmetry theory championed by Witten, there is no evidence for the string theory speculations he has advanced. But for decades physicists have wasted time cranking out thousands of speculative papers on string theory and supersymmetry theory. For decades physicists regarded Witten as kind of the High Priest of string theory, and they kept saying he was the smartest physicist. But what has come from all these string theory papers? Just a lot of speculation and mathematical gymnastics.
A recent interview with Witten is a sad affair with a "sound of failure" ring to it. He rather seems to acknowledge the failure of supersymmetry, saying that "it has been very hard to find a conventional natural explanation of the dark energy and hierarchy problems," and that "it seems that the ideas of naturalness that we grew up with are failing us in at least these two cases." He mentions two great fine-tuning problems, one the Higgs mass fine-tuning problem, the other the dark energy fine-tuning problem, involving even greater apparent fine tuning. Both involve involve apparent fine-tuning of greater than 1 part in 1030, as does the fine-tuning of the universe's initial expansion rate. Witten seems to throw his hands up and reluctantly express sympathy for the idea of the multiverse "landscape," under which there are an infinite or near infinite number of universes, each with different physics. He says he resisted this idea before, but is now warming to it. The idea was dreamed up by another string theorist (Leonard Susskind), specifically for the purpose of evading evidence for design in the universe (we can tell this from the title of a book Susskind wrote introducing the term "landscape" for such an imagined multiverse).
Such a multiverse is a "when all else fails" type of last-resort fallback. Physicists and cosmologists will try desperately to explain away various types of cosmic fine-tuning, speculating like crazy, and trying to come up with some scenario that helps sweep some of the fine-tuning under the rug. When after decades of fiddling with such flights of fancy, they find all such efforts flopping and failing everywhere, their desperate last resort is to "grasp at straws" by appealing to some "all possibilities realized" multiverse.
Resorting to such a thing is futile. The issue is why our universe would have such almost infinitely improbable favorable conditions. You do not increase the probability of such a thing by even 1% by imagining some infinity of universes, each with different conditions. Such a multiverse may increase the likelihood of some universe being habitable, but does nothing to increase the likelihood of our universe being habitable. Similarly, I do not even increase by 1% the chance that I will get ten consecutive royal flushes when playing poker if I postulate that there are an infinity of poker players.
Our multiverse theorists are guilty of the most elementary error in logic, failing to distinguish between a "some universe" likelihood and an "our universe" likelihood, or conflating the two. Below are some good principles to remember:
(1) Never assume that because some person is very smart and has learned very much that he would not commit the most elementary and obvious error in logic.
(2) Never assume that his "singing from the same choir book" colleagues (spellbound by groupthink and hero idolizing) would fail to recognize such an elementary and obvious error in logic.
(3) Never assume that because some person is very smart and has learned very much that he would not advance some theory that is absurd or groundless, and utterly unworthy of belief.
(4) Never assume that any theory lacking a sound observational basis is science rather than ideology mixed up with speculative narration or mathematics, what we may call metaphysics wearing an "I'm science!" T-shirt.
From the standpoint of advancing human knowledge, theories such as the cosmic inflation theory (not to be confused with the more general Big Bang theory), supersymmetry and string theory have been futile flops. They went viral, but were never validated by observations. There is only one standpoint from which such theories have been successful: they have provided a type of lucrative busy work for physicists and cosmologists, who have received tons of government money for the armchair activity of writing wildly speculative papers. A similar thing would have gone on if the government had paid theologians very many millions to speculate about the living conditions of angels and the visual characteristics of heaven.
The latest Symmetry magazine article on supersymmetry gives us some quotes that should cause a chuckle, such as this one:
"The lack of evidence for supersymmetry at the LHC does not signify a death knell for the idea. Nevertheless, 'now the community is going off in a large number of different directions,' Peskin says. 'We’re all pretty confused right now.' ”
The article also makes it clear that the supersymmetry faithful will cling to their cherished speculations for a long, long time, kind of like some religious community waiting for centuries for its promised messiah. We read this:
"It could be decades before physicists know the truth about supersymmetry. If superpartners exist, Gates says that up to a century could pass before their discovery. But 'we know how to be patient as a community,' Herwig says."
No comments:
Post a Comment