NEUTRINOS: The Lightest Matter in the Known Universe

neutrinos the trillions of tiny particles streaming imperceptibly through your body at this very moment could force us to question our understanding of the very laws of physics neutrinos are so obscure and difficult to detect that they break our current theories of modern physics do they have no Mass like a photon do they have a tiny amount of mass so small that it barely interacts with the higs field or could they as suggested by recent findings Based on data from the Desi survey even even have negative Mass a concept so bizarre that it defies explanation I'm Professor Brian keading and in this video I'll talk about everything we now know and plenty of things we don't about neutrinos if we can answer our questions about these all pervasive ghostly subatomic particles we may discover the key to unlocking the underlying Mysteries of the cosmos dark energy and why some galaxies form and others don't in 1930 Austrian theoretical physicist Wolf Gang poy sent a letter that would become famous in the world of particle physics a letter he wrote in response to strange observations he couldn't reconcile the letter stated that in his attempt to reconcile wrong statistics in the decay of the beta or electron emission spectrum P's observations showed that in the process of beta Decay an electron would be emitted only problem was the measured energy of the electron that was emitted was not consistent and it was a result that counteract the law of conservation of energy the most sacred law in all of physics his desperate remedy was to propose the existence of a counter particle one that would offset the changes in energy and motion that he observed unfortunately as po put it one should have seen these earlier if they really existed he famously said I have done a terrible thing I have postulated a particle that cannot be detected nearly 30 years later Po's desperate conjecture was pursued further by two Rogue physicists Clyde and Frederick rinus C and rhus were working on Atomic physics stationed at Los Alamos where the atomic bomb and the Manhattan Project took place they were working on nuclear experiments and believed that the only way they could possibly generate enough neutrinos to measure was to detonate a mere 20 kiloton nuclear bomb similar to the one dropped on hoshima and Japan this outlandish plan required creating a massive detector and then dropping it 150 ft into the Earth during the explo expon so that it could measure in midair without the shock wave of the nuclear explosion destroying the very detector itself at the last minute The two scientists realized that possibly they could get away with a less explosive environment a nuclear reactor could actually be substituted for the atomic bomb and after multiple confirmation tests they finally made the first confirmed recordings of the existence of the neutrino validating Pal's wild hypothesis and winning them the Nobel Prize as well neutrinos were determined to be subatomic parts particles Elementary particles with no electric charge and an unknown mass for most of History it was believed that they had no mass at all that was until 1998 when scientists in Japan were using the super Kam aande experiment over time the scientists found out that neutrinos come in different variations known as flavors there's three flavors electron muon and T flavors technically all neutrinos exist in a state of superposition until they're observed like trillions of subatomic shringer cats zipping around the universe electron neutrinos were the first observed variation as seen by Cowan and rhinos when measuring next to their nuclear reactors however in the super Kamia experiment Japanese scientist realized that neutrinos were able to oscillate or change from one flavor to another when measuring atmospheric neutrinos produced by cosmic rays slamming into the Earth's atmosphere the superon scientist observed that muon neutrinos coming from the opposite side of the earth were disappearing slightly more often than expected this disappearance was consist to the nutrino oscillating into another flavor in this case likely Town neutrinos which superame aande could not easily detect this aligned with earlier observations reconfirmed by the super Kamia experiment where researchers observed fewer electron neutrinos emanating from the Sun the so-called solar nutrino problem the missing neutrinos were confirmed to have made it that 93 million mile Journey but during their Voyage they had oscillated to different flavors leaving only a smaller percentage of the original nutrino flavor able to be detected flavor oscillation like this isn't possible unless neutrinos have some tiny amount of mass this was huge news as it contradicted the standard model of particle physics original prediction but according to the quantum physics of flavor oscillation neutrinos needed Mass to oscillate further experiments confirm the observations and it's been accepted that the standard models prediction was wrong and needed to be revolutionized now we've talked about mass and the tiny mass of the neutrino but what is mass and why does it matter if you forgive that Dad joke you'll probably remember that mass is a property of matter that resists acceleration what we call inertia and it causes objects to interact gravitationally with other massive objects unlike energy matter is not conserved and for most particles the Hig field provides the interaction that we call Mass the higs field is a fundamental field spread throughout the entire universe we call excitations of the higs field the higs bong and in our current model of physics particles acquire mass by interacting with the higs field confirming the exist of the higs field required detecting the associated particle which we call the higs Bon this was achieved in 2012 at cern's large hyron collider but neutrinos are still just as mysterious as they were decades ago as it comes to their interaction the mass that they acquire is so tiny it's less than 1 millionth of the mass of the next lightest particle the electron but if they do interact with the higs field it would be at an incredibly unprecedentedly weak reaction since their mass is so minimal so why don't these little vespers follow the standard rules of mass acquisition neutrinos due to their low mass stream through the universe at nearly the speed of light they pass through basically everything unimpeded only very occasionally do they interact primarily via the weak nuclear force and because of this they don't Clump together in the same way that heavier particles from electrons to protons and neutrons do when those protons and neutrons form from free quarks after the big bang they eventually molded into Atomic nuclei protons are bound together to desite their electronic repulsion by an even stronger Force which is unsurprisingly called the strong nuclear force when electrons bind to those nuclei we create atoms those atoms can then create molecules larger particles say of dust of rock of ice and eventually things like stars galaxies planets and podcasters neutrinos are more subtle though they spread out soon after the big bang and they do contribute to the amount of mass energy in the early universe but their function is to smooth it out over larger and larger structures they influence the formation of galaxies in interesting ways their tiny mass is enough to delay the formation of the onset of structure of galaxies and clusters of galaxies which led the universe to have more large galaxies than expected if these neutrinos did not have some amount of mass and this is because the fast-moving light neutrinos suppress the growth of small structures while larger structures are able to form by studying the distribution and formation of galaxies and clusters of galaxies we can indirectly extract the nutrino mass and how they affected our Cosmic architecture a measurement of their Mass this makes them unique as the only type of the 17 Elementary particles the three neutrinos are the only three whose mass is unknown and unmeasured laboratory experiments and cosmology experiments provide upper limits the maximum Mass they can have and nutrino oscillation experiments we've already discussed provide a lower limit must be bigger than a certain value but these are hardly something to write home about imagine going to a doctor and saying you weigh somewhere between 1 lb and 2,000 lb if we want to go further we need more and better data so how is it a question so seemingly fundamental has eluded us and could there be another explanation for the neutrino inexplicable interactions with the higs field and their apparently minuscule spell Mass while scientists have been unable to pin down a clear mass for the neutrino they have been hard at work looking at all possibilities narrowing it down and several attempts are underway to measure and establish a firm value for its Mass another attempt is to establish a possible floor and a given ceiling a range of possibilities for the nutrino weight class the problem is there are disagreements even in those windows and sometimes even outright contradiction let's look at the two battling factions in the quest to measure the mass of the nrin on one side there are teams looking at the particles up close to observe the effects of mass directly in Japan the descendant of the super kamande experiment the hyper kamande experiment is under construction and it will be about 20 times larger than its elder brother with a volume of 260,000 tons of Highly purified water like the superame ande detector it'll be housed deep underground in a mine to Shield it from cosmic rays and other sources of background contamination and noise this facility and similar ones like the Dune laboratory in the United States all are created to observe nutrino interactions on Earth continuing in the footsteps of the original discoveries of the nutrino oscillations themselves the other approach are those that are looked to the Heavens to infer the mass of the nutrino from large clusters and structures in the earlier Universe neutrinos created just a few seconds after the universe itself have left imprints on the cosmic microwave background radiation the cmbb which is the faint Afterglow of the Big Bang the area of research I engages by studying the cnb's temperature and polarization patterns scientists and colleagues of mine have discovered a unique phase shift caused by these neutrinos incredibly these phase shifts induced in the structure and pattern of structure the harmonics of the early Universe help us understand neutrino properties including their masses by mapping galaxies and clusters of galaxies with exquisite Precision experiments like Desi the dark energy spectroscopic instrument capture crucial data for estimating nutrino masses in April 2024 Desi released spectacular measurements that suggest a floor and a ceiling to the mass of neutrinos that contradicts our close-up observations on laboratory experiments on Earth this dramatically Narrows the Nino Mass window so much so that it approaches zero Mass which we know is in conflict with the neutrino Mass oscillation experiments this led members of a team of theorist led by Dan Green and Joel Myers and other scientists using Desi's data to speculate that perhaps the actual mass implied could be less than zero this is a result that they didn't initially assume was sensible but after they removed that constraint a measurement of negative nutrino Mass was reported and since then this has hardly been the last time that negative Mass has been proposed to solve cosmological conundrum in November 2024 scientists plugged in new values into Einstein's relativity equations to understand how the universe's increasingly expanding rate the so-called hobble tension that physicists have observed for more than a decade physicist Manu parang and sosen mabarak claimed that areas of SpaceTime could theoretically emerge as negative Mass bubbles in these Bubbles and voids our assumptions about Mass would be reversed with massive objects repelling everything that was close to them in contrast to the way normal gravity behaves likewise they would attract objects more and more strongly when they were more and more distant if negative Mass could truly exist and is connected to the unimaginable numbers of neutrinos in our universe and their properties it would certainly require us to rewrite the laws of physics as we know them and all this could shed light on cosmological law observations about the rate of expansion of the universe in the first moments of cosmic inflation immediately following the Big Bang of course not everyone's convinced by the claims of Daniel Green and Joel Meyers the idea of negative nutrino mass is essentially an athema to many colleagues in particle and fundamental physics it sparked a heated debate critics argue it's as far-fetched as claiming a perpetual motion machine even some scientists reporting their findings from the Desi experiment reported that it could be a symptom of another underlying problem in the data or a mirage a so-called systematic effect a mysterious phenomenon that's not understood whether in the data or even in the astrophysics that go into the calculations of the behavior at a theoretical level of how these galaxies should be clustered this could change the growth rate of structure suggesting that it's less dominated by neutrinos than previously accepted the battle to determine the nutrino Mass be it positive zero or even negative goes on these fundamental particles may be invisible barely registering as matter but their fingerprints as ghostly as they are everywhere from the patterns of the cosmic microwave background radiation to sculpting the clustering of galaxies on the largest scales in the cosmos while the prognosis is still speculative it's only in exploring these seemingly outrageous ideas that we continue to push the boundaries of science uncovering ideas that may one day take us to the edge of the cosmos if you enjoyed this journey into those strange and wonderful world of these Poltergeist particles called neutrinos watch my interview with Dan Green and my friend Eric Weinstein on the biggest questions in modern physics I'm Professor Brian keing and until next time keep looking up and asking and always be curious