Chandra Telescope Data Throws Shade on 'Theory of Everything'

Recently analyzed data from Chandra throws shade on string theory because expected particles — similar to one called 'axion' — didn't show up.
Brad Bergan

In physics, there's an idea about the universe — some more theoretical than others — that every force, particle, and interaction is connected in one network described by a single, elegant theory. String theory is one popular proposal for such a "theory of everything," and — while there are many takes on string theory throughout the physics community — few exist with experimental bases.

Until now.

Recently, a new study sought specific particles predicted by several models of string theory, and found nothing, lowering the credibility of some models, reports


Axions are crucial for string theory

Researchers of the study sought a unique particle called "axion." No one had yet detected these particles of exceptionally low mass. No one even knew the range of masses these particles should span. But — while non-detection doesn't cancel their theoretical viability completely — it strikes a critical blow to some models within the family of ideas about string theory.

"Until recently I had no idea just how much X-ray astronomers bring to the table when it comes to string theory, but we could play a major role," said the University of Cambridge's Christopher Reynolds, who led the study. "If these particles are eventually detected it would change physics forever."

One wild property of these ultra-low-mass particles is their capacity to sporadically convert into photons (they mean light) as they (or it) move(s) through magnetic fields. But the opposite happens too: sometimes circumstances turn photons back into axions. How often conversions happen depends on their "convertibility."

However, some scientists have suggested the existence of a broader class of ultra-low-mass particles — similar in properties to axions — but more flexible.

Axion-like particles, the flexible alternative

Where ordinary axions would have one lone convertibility value at each specific mass, these alternative "axion-like particles" would display a range of convertibility values at the same mass.

"While it may sound like a long shot to look for tiny particles like axions in gigantic structures like galaxy clusters, they are actually great places to look," said David Marsh, co-author of the study, from Stockholm University in Sweden, according to "Galaxy clusters contain magnetic fields over giant distances, and they also often contain bright X-ray sources. Together these properties enhance the chances that conversion of axion-like particles would be detectable."

Throwing shade on the 'theory of everything'

Looking for signs of axion-like particle conversion, the team of astronomers assessed more than five days of Chandra observations of X-rays from material falling helplessly toward the supermassive black hole at the center of the Perseus galaxy cluster. The team's study of the bright X-ray source unveiled a spectrum with a sensitivity at which distortions were predicted to occur in the presence of axion-like particles.

Since no distortions of this kind were detected, the researchers ruled out the presence of most kinds of axion-like particles in the requisite mass range — roughly one-millionth of a billionth of an electron's mass. 

While their research doesn't rule out the existence of axion-like particles completely, this represents an "underrated tweet" of science: progress made by disconfirming scientific theories is just as important as (although less exciting than) affirmative discoveries. It will be less exciting, but more significant when scientists declare the COVID-19 coronavirus is no longer a threat — than it was when the novel virus first swept across the planet.

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