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+--- Thread: Colliding photons were spotted making matter + Hints of a new fundamental force (/thread-10771.html)
Colliding photons were spotted making matter + Hints of a new fundamental force - C C - Aug 10, 2021
Colliding photons were spotted making matter. But are the photons ‘real’?
https://www.sciencenews.org/article/colliding-photons-matter-particle-physics
EXCERPTS: Collide light with light, and poof, you get matter and antimatter. It sounds like a simple idea, but it turns out to be surprisingly hard to prove.
A team of physicists is now claiming the first direct observation of the long-sought Breit-Wheeler process, in which two particles of light, or photons, crash into one another and produce an electron and its antimatter counterpart, a positron. But like a discussion from an introductory philosophy course, the detection’s significance hinges on the definition of the word “real.” Some physicists argue the photons don’t qualify as real, raising questions about the observation’s implications.
Predicted more than 80 years ago, the Breit-Wheeler process had never been directly observed [...] “The idea that you can create matter from light smashing together is an interesting concept,” says Brandenburg. It’s a striking demonstration of the physics immortalized in Einstein’s equation E=mc2, which revealed that energy and mass are two sides of the same coin.
Whether the observation truly qualifies depends on whether the photons are considered “real,” as demanded by the Breit-Wheeler process, or “virtual.” In particle physics, virtual particles are ones that appear only for brief instants and don’t carry their normal masses.
Photons from a commonplace source of light, like a lightbulb or a laser, are real, physicists agree. But the bona fides of Brandenburg and colleagues’ photons are up for debate. That’s because the light the team is colliding comes from an unusual source.
In the Relativistic Heavy Ion Collider, atomic nuclei travel at nearly the speed of light before ramming into one another. Those speedy nuclei are surrounded by electromagnetic fields, and those fields have photons associated with them. Normally, such photons from electromagnetic fields are virtual. But in the experiment, the photons act as if they are real due to the high speeds at which the two nuclei are zipping along... (MORE - details)
Hints of a new fundamental force
https://iai.tv/articles/hints-of-a-new-fundamental-force-auid-1858
EXCERPT: . . . Yet almost a decade later, after literally thousands of searches performed by the four big LHC experiments, nature has stubbornly refused to give up its secrets. After the discovery of the Higgs, the LHC experiments continued to verify the predictions of the standard model, while ruling out a whole host of speculative new theories that were intended to extend it into new territory.
Some began to talk about a crisis in particle physics. Could it be that the long quest for an ever-deeper understanding of the fundamental constituents of our universe had reached a dead end? However, amid the gathering gloom, a series of unexpected chinks of light were beginning to appear.
Once again, particle physics made headline news around the world. Major discoveries seemed to be arriving like buses.
The LHCb experiment, one of the four giant detectors that study particle collisions produced by the LHC and the experiment on which I work, was reporting a growing number of ‘anomalies’; measurements that seemed to be in tension with the predictions of the standard model. While intriguing, for a long while these deviations were too subtle for physicists to have much confidence that they were anything other than random statistical wobbles in the data. That is until the 23rd March of this year.
On that day, my colleagues at LHCb announced they had found firm evidence for exotic particles known as beauty quarks decaying in ways that the standard model can’t explain. If borne out, these results suggest the existence of a brand-new force of nature, which would make it arguably the most momentous scientific discovery of the 21st century so far. The story broke out into the mainstream media, quickly making it one of the most widely covered particle physics stories since the discovery of the Higgs in 2012.
Then, just two weeks later on the 7th April, a completely different experiment at Fermilab in the United States announced a second result that seemed to suggest that fundamental particles called muons were also experiencing the tug of a hitherto undiscovered force. Once again, particle physics made headline news around the world. Major discoveries seemed to be arriving like buses.
So, what is going on? Are we really on the brink of a breakthrough, or are we being led astray by cruel quirks of the data? To answer that question, we need to delve a little deeper into what exactly these experiments have seen... (MORE - details)