Cosmologic philosophy: physics current dead end (Introduction)

by David Turell , Friday, March 04, 2022, 20:11 (776 days ago) @ David Turell

Another new analysis shows the LHC has failed:

https://www.quantamagazine.org/crisis-in-particle-physics-forces-a-rethink-of-what-is-n...

"The crisis became undeniable in 2016, when, despite a major upgrade, the Large Hadron Collider in Geneva still hadn’t conjured up any of the new elementary particles that theorists had been expecting for decades. The swarm of additional particles would have solved a major puzzle about an already known one, the famed Higgs boson. The hierarchy problem, as the puzzle is called, asks why the Higgs boson is so lightweight — a hundred million billion times less massive than the highest energy scales that exist in nature. The Higgs mass seems unnaturally dialed down relative to these higher energies, as if huge numbers in the underlying equation that determines its value all miraculously cancel out.

"The extra particles would have explained the tiny Higgs mass, restoring what physicists call “naturalness” to their equations.

***

"Their introspection is bearing fruit. Researchers are increasingly zeroing in on what they see as a weakness in the conventional reasoning about naturalness. It rests on a seemingly benign assumption, one that has been baked into scientific outlooks since ancient Greece: Big stuff consists of smaller, more fundamental stuff — an idea known as reductionism. “The reductionist paradigm … is hard-wired into the naturalness problems,” said Nima Arkani-Hamed, a theorist at the Institute for Advanced Study in Princeton, New Jersey.

"Now a growing number of particle physicists think naturalness problems and the null results at the Large Hadron Collider might be tied to reductionism’s breakdown. “Could it be that this changes the rules of the game?” Arkani-Hamed said.

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"The search for supersymmetric partner particles began at the Large Electron-Positron Collider in the 1990s. Researchers assumed the particles were just a tad heavier than their Standard Model partners, requiring more raw energy to materialize, so they accelerated particles to nearly light speed, smashed them together, and looked for heavy apparitions among the debris.

"Meanwhile, another naturalness problem surfaced.

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"...cosmologists observe that space’s expansion is accelerating only slowly, indicating that the cosmological constant is small. Measurements in 1998 pegged its value as a million million million million million times lower than the Planck energy. Again, it seems all those enormous energy injections and extractions in the equation for the cosmological constant perfectly cancel out, leaving space eerily placid.

"Both of these big naturalness problems were evident by the late 1970s, but for decades, physicists treated them as unrelated.

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"Physicists refer to low-energy, long-distance physics as “the IR,” and high-energy, short-distance physics as “the UV,” drawing an analogy with infrared and ultraviolet wavelengths of light.

"In the 1960s and ’70s, the particle physics titans Kenneth Wilson and Steven Weinberg put their finger on what’s so remarkable about nature’s hierarchical structure: It allows us to describe goings-on at some big, IR scale of interest without knowing what’s “really” happening at more microscopic, UV scales.

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"UV-IR mixing potentially resolves naturalness problems by breaking EFT’s reductionist scheme. In EFT, naturalness problems arise when quantities like the Higgs mass and the cosmological constant are UV-sensitive, yet somehow don’t blow up, as if there’s a conspiracy between all the UV physics that nullifies their effect on the IR.

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"...the CKN bound implies that there may be far, far less high-energy activity than the EFT calculation assumes — meaning precious few high-energy states available for particles to occupy. Cohen, Kaplan and Nelson did a simple calculation showing that, for a box the size of our universe, their bound predicts more or less exactly the tiny value for the cosmological constant that’s observed.

"Their calculation implies that big and small scales might correlate with each other in a way that becomes apparent when you look at an IR property of the whole universe, such as the cosmological constant.

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"Taken together, the new UV-IR mixing models illustrate the myopia of the old paradigm — one based solely on reductionism and effective field theory — and that may be a start.

“'Just the fact that you lose reductionism when you go to the Planck scale, so that gravity is anti-reductionist,” Dubovsky said, “I think it would be, in some sense, unfortunate if this fact doesn’t have deep implications for things which we observe.'”

Comment: now see Rob Sheldon's comment in Uncommon descent:

https://uncommondescent.com/intelligent-design/deepening-crisis-in-particle-physics-rob...

I'll reproduce it next.