Science - Has A New Discovery Broken Known Physics?

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Science - Has A New Discovery Broken Known Physics?
By: Don Lincoln - Science & Forbes - 11-23-19
RE: https://www.forbes.com/sites/drdonli.../#303bfdd565be

Science and the Internet have an uneasy relationship. Science is a community of sober and careful individuals who work very hard to release only solid results that have survived thorough and critical review. When that is done, the Internet can quickly disseminate the discovery quickly to a wide audience. On the other hand, the Internet frequently isn’t big on caution and nuance, and a story can spread widely before there is a scientific consensus.

Stories that report a discovery that extends or even breaks the current theoretical paradigm should be viewed extremely skeptically. A recent scientific paper claiming to have discovered a new particle that would mean a new and undiscovered force is one such paper. This doesn’t mean that the discovery is wrong – indeed a paradigm-changing discovery would look very similar – it’s just that we should remember Carl Sagan’s wise admonition that extraordinary claims require extraordinary evidence. So, just what is this new scientific announcement?

A group of scientists working at a Hungarian Research Institute called Atomki claim to have found a new particle with a mass of 17 million electron volts (MeV). This particle, if confirmed, is about 33 times heavier than an electron and about two percent the mass of a proton.

They did this by studying a nuclear transition of a helium nucleus. In this transition, a gamma ray (e.g. photon) of 21 MeV of energy is released. At such high energies, the photon can convert into an electron and antimatter electron (positron) pair, and the angle between the paths of these two particles can be measured. Standard nuclear theory makes a clear prediction of the distribution of angles between these two particles.

When the researchers made this measurement, they found an unexpected excess of pairs of particles with an angle between their trajectories of 115º. This excess can be explained if an unknown particle with a mass of 17 MeV was made.

Such a discovery, if confirmed, would be grounds for celebration. Perhaps a new particle and a new force has been discovered. The story is made even more interesting because the same group made a similar announcement back in 2015 in a similar nuclear transition in beryllium, leading to an electron/positron pair and an excess of occurrences of trajectories with an opening angle of 140º. In the context of the beryllium measurement, the excess could also be explained as the creation of a heretofore undiscovered particle with a mass of 17 MeV, representing a new and unknown force. Thus, the recent measurement could be considered a confirmation of the earlier one. Furthermore, after the earlier discovery in beryllium transitions, a group of theoretical physicists devised a theory that was (a) consistent with all previous measurements and (b) predicted a new particle with a mass of 17 MeV.

So, does this mean that the champagne should be popped, and the Nobel Prize committee be notified? Well, no; not so fast.

While word of this discovery has spread across the Internet, the scientific community is not yet convinced and not convinced for several reasons. First the positive things. The first observation of this possible new particle created in beryllium transitions was submitted for peer review and the measurement was published in Physical Review Letters, a leading and highly respected physics journal. This means that the first measurement was evaluated by peer scientists and considered worthy of dissemination. Furthermore, the theoretical physicists who devised the explanatory theory are established and well regarded, and their theory was also published in the same journal This means that the theory has withstood at least cursory critical evaluation.

But the situation is not all positive. The two measurements, both the one involving helium and the other investigating beryllium, were performed by the same group. This is not truly independent confirmation. Furthermore, other experimental groups which should have been able to detect a particle with a mass of 17 MeV and the required properties have looked and found nothing. Thus, the particle cannot really be considered confirmed. Indeed, some would say that it has been refuted.

In addition, the theoretical framework proposed to explain the new discovery was very unusual. In the theory, the new particle would not interact with protons at all, what scientists call protophobic, and could only interact with neutrons, what scientist call neutrophillic. While this is not impossible, it is a very specific prediction, without anything comparable.

Finally, the more senior scientists who announced the supposed discovery of the 17 MeV particle have, over the last few decades, claimed the observation of a series of other particles, none of which have been confirmed by other groups. While previous examples of unconfirmed discoveries do not negate this one, this fact must give one pause.

So, what does this mean? Well, it is certainly possible that researchers have stumbled on something that no other group has found – after all, they are degreed scientists, with access to professional equipment. However, their history of unconfirmed announcements and lack of confirmation by other researchers suggests that extreme caution is in order. It would be hasty to consider the 17 MeV particle as established fact.

Debates like these – with scientists making claims and others trying to confirm or disprove them – are common in the scientific community. However, the advent of the easy communication of the Internet has allowed non-scientists to see the debate – how the sausage is made, so to speak. At the moment, the most prudent course of action is to wait for other groups to either confirm the announced discovery or to make additional measurements that prove it to be an example of an interesting bit of data that didn’t live up to its original billing.

About this writer: Don Lincoln is a senior scientist at Fermilab, America’s flagship particle physics laboratory, who has coauthored over 1,200 publications and was part of the discovery of both the top quark and the Higgs boson. I write extensively for the public on the topics of particle physics in cosmology, with several books, including “The Large Hadron Collider.” I also make videos on similar topics, both with The Great Courses Company and on the Fermilab YouTube channel. I have won awards from both the European Physical Society and the American Institute of Physics for my popular science writing, and I am a Fellow of both the American Physical Society and the American Association for the Advancement of Science.