Does Particle Physics Have A Future On Earth?
“Will it be successful? Regardless of what we find, that answer is unequivocally yes. In experimental physics, success does not equate to finding something, as some might erroneously believe. Instead, success means knowing something, post-experiment, that you did not know before you did the experiment. To push beyond the presently known frontiers, we’d ideally want both a lepton and a proton collider, at the highest energies and collision rates we can achieve.
There is no doubt that new technologies and spinoffs will come from whichever collider or colliders come next, but that’s not why we do it. We are after the deepest secrets of nature, the ones that will remain elusive even after the Large Hadron Collider finishes. We have the technical capabilities, the personnel, and the expertise to build it right at our fingertips. All we need is the political and financial will, as a civilization, to seek the ultimate truths about nature.”
With the discovery of the Higgs boson and nothing else at the LHC, many physicists are legitimately entertaining what’s been called the “nightmare scenario,” where no new particles exist beyond the Standard Model that can be discovered by terrestrial colliders. But it isn’t a foregone conclusion that there aren’t such particles, and there are two generic types of plan for how we might find any new particles that do exist beyond the LHC’s reach. If the experimental particle physics community comes together to develop a single, coherent proposal for their future, we could probe the frontiers of nature as never before.
Does particle physics have a future on Earth? It should, and here’s what I would recommend they choose if they have the political and financial will to do so.
No, Physicists Still Don’t Know Why Matter (And Not Antimatter) Dominates Our Universe
“According to the hot Big Bang, the Universe as we know it today was born 13.8 billion years ago, and was filled with energy in the form of photons, particles, and antiparticles. The Universe was hot, dense, and expanding extremely rapidly under those early conditions, which caused the Universe to cool. By the time less than a single second had passed, practically all of the antimatter had annihilated away, leaving approximately 1 proton and 1 electron for every 1 billion photons.
The Universe was thought to be born matter-antimatter symmetric, as the laws of physics dictate. But something must have happened during that first fraction-of-a-second to preferentially create matter and/or destroy antimatter, leaving an overall imbalance. By the time we get to today, only the matter survives.”
In a really cool experiment at CERN, enormous numbers of particles called mesons, containing one quark and one antiquark, are produced and studied. Some of those particles contained charm quarks, while others contained charm antiquarks. When they decayed, there was a slight difference in the ratios of what their decay products were, indicating a fundamental asymmetry between matter and antimatter.
But this was already seen in both strange quark and bottom quark systems, and doesn’t explain our Universe’s matter-antimatter asymmetry. Get the full story here.
Why Physics Needs, And Deserves, A Post-LHC Collider
“If what we observe and measure is identical to what the Standard Model predicts, then we haven’t found anything new. So far, that’s what the LHC has revealed: particles that behave in perfect accord with the Standard Model.
But there might be new particles out there. There might be new physics, new forces, new interactions, new couplings, or any slew of exotic scenarios. Some of them are scenarios we haven’t even yet envisioned, but the dream of particle physics is that new data will lead the way. As we peel back the veil of our cosmic ignorance; as we probe the energy frontiers; as we produce more and more events, we start obtaining data like we’ve never had before.”
There are some big differences between theorists and experimentalists. Theorists look at the big picture, come up with their preferred hypotheses and ideas, and work to create a consistent, predictive framework that provide possible signatures of what might extend our knowledge of the Universe. But experimentalists have, as their main goal, to gather more data and probe what is currently unknown. Both work hard to extend our knowledge of the Universe, but experimental results are useful and interesting in their own right, regardless of what truths they do or do not reveal. To some, the LHC’s results, discovering a Standard Model Higgs, and nothing else new, have led to a nightmare scenario.
But the real nightmare would be if we didn’t ask the Universe the next set of questions that a future collider experiment could answer. Learn what could come next today!
Is Anti-Gravity Real? Science Is About To Find Out
“It’s an incredible possibility, one that’s considered wildly unlikely by practically all theoretical physicists. But no matter how wild or tame your theories are, you must absolutely confront them with experimental data; only through measuring the Universe and putting it to the test can you ever accurately determine how the laws of nature work.
Until we measure the gravitational acceleration of antimatter to the precision necessary to determine whether it falls up or down, we must keep ourselves open to the possibility that nature might not behave as we expect. The equivalence principle may not be true for antimatter; it may, in fact, be 100% anti-true. But if that’s the case, a whole new world of possibilities will be unlocked. We could change the currently-known limits of what humans can create in the Universe. And we’ll learn the answer in just a few years through the simplest of all experiments: putting an anti-atom in a gravitational field, and watching which way it falls.”
One of the biggest problems with manipulating gravity is that there’s only one type of gravitational charge: the positive kind. Mass has positive gravity, and it attracts all other masses. Energy also has positive gravity, and attracts and is attracted to all other forms of energy. The curvature of spacetime can only be positive or zero; negative gravitational attraction is impossible in a Universe without negative gravitational mass. But we’ve never measured the gravitational effects on antimatter, and a new experiment just might be the first to get there.
If antimatter anti-gravitates, our sci-fi dreams like artificial gravity and warp drive will suddenly become possible. Keep your mind open and your dreams alive.
Has The Large Hadron Collider Accidentally Thrown Away The Evidence For New Physics?
“It’s eminently possible that the LHC created new particles, saw evidence of new interactions, and observed and recorded all the signs of new physics. And it’s also possible, due to our ignorance of what we were looking for, we’ve thrown it all away, and will continue to do so. The nightmare scenario — of no new physics beyond the Standard Model — appears to be coming true. But the real nightmare is the very real possibility that the new physics is there, we’ve built the perfect machine to find it, we’ve found it, and we’ll never realize it because of the decisions and assumptions we’ve made. The real nightmare is that we’ve fooled ourselves into believing the Standard Model is right, because we only looked at one-millionth of the data that’s out there.”
Ten years. Over 200 Petabytes of data. That’s how long it’s been and how much data has been collected since the Large Hadron Collider first turned on. During its data-taking runs, the LHC collided bunches of protons at the incredible speed of 299,792,455 m/s: just 3 m/s slower than the speed of light. Bunches smashed together roughly every 25 nanoseconds inside each detector, and we’ve written that data down as fast as our electronics and the limits of physics will allow.
But even at that, it means that 99.9999% of the collision data needed to be discarded. We’ve only collected data from 1-in-a-million collisions, and that’s a big potential problem. We haven’t seen any evidence for physics beyond the Standard Model there, and one can’t help but wonder if maybe there’s an alternative to the nightmare scenario.
Perhaps new physics is out there, right at our fingertips, and we’ve simply missed it because of what we’ve thrown away. Perhaps the “nightmare” is one we brought upon ourselves.
Five Years After The Higgs, What Else Has The LHC Found?
“There is every reason to be optimistic, since the LHC will produce tons of b-mesons and b-baryons, as well as more Higgs bosons than every other particle source combined. Sure, the biggest breakthrough we could hope for would be the detection of a brand new particle, and evidence for one of the great theoretical breakthroughs that have dominated particle physics in recent decades: supersymmetry, extra dimensions, technicolor, or grand unification. But even in the absence of that, there is plenty to learn, at a fundamental level, about how the Universe works. There are plenty of indicators that nature plays by rules we have not yet fully discovered, and that’s more than enough motivation to keep looking. We already have the machine, and the data will be on its way in unprecedented amounts very soon. Whatever new hints are hiding at the TeV scale will soon be within reach.”
There are lots of calls out there for the LHC to be the last great particle physics collider out there, as fears that there’s nothing new to discover at the energies we can create grip the community. After all, the great hope was that they would find new, unexpected particles at CERN, and that would guide the way forward in the field with experimental evidence. Well, we didn’t get as lucky as we could have, but there are plenty of reasons to be optimistic: there appears to be new physics in the b-quark sector; we’re entering the era of precision Higgs measurements; and the total amount of data we’ve obtained at the LHC is just 1/50th of the total amount we’ll wind up with after Runs III, IV and V are complete. Just because the greatest victory we could have imagined didn’t come true doesn’t mean there isn’t an incredible amount left to learn from this remarkable machine.
Come see, five years on, what we have and haven’t found. The future of particle physics is bright even without made-up evidence for our favored hypotheses!
Nuclear Physics Might Hold The Key To Cracking Open The Standard Model
“Interestingly, this could also lead to a renewed interest in the search for glueballs, which would be the first ever direct evidence of a bound state of gluons in nature! If the exotic QCD predictions of tetraquarks and pentaquarks are borne out in our Universe, it stands to reason that glueballs should be there as well. Perhaps the existence of these composite particles will be verified at the LHC as well, with incredible implications for how our Universe works either way.”
Nuclear physics has, for decades now, been regarded less as a window into fundamental physics and more of a derived science. As we’ve discovered that nuclei, baryons, and mesons are all composite particles made out of quarks, antiquarks, and gluons, though, we’ve realized that there are other possible combinations that nature allows, that should exist. In recent years, we’ve discovered tetraquark and pentaquark states of quarks and antiquarks, and yet there should be even more. QCD, our theory of the strong interactions, predicts that a set of exotic states of bound gluons – known as a glueball – should exist. Finding them, or proving that they don’t exist, might be a way to crack open the Standard Model in an entirely new way.
Nuclear physics might, after all these years, hold the key to going beyond the current limitations of physics.