Category: particle

How Do We Know How Small An Elementary Particl…

How Do We Know How Small An Elementary Particle Is?

“But here’s the thing: we don’t know that this is true. Sure, the Standard Model says that this is the way that things are, but we know that the Standard Model doesn’t give us the final answer to everything. In fact, we know that at some level, the Standard Model must break down and be wrong, because it doesn’t account for gravity, dark matter, dark energy, or the preponderance of matter (and not antimatter) in the Universe.

There has to be something out there more to nature than this. And maybe it’s because the particles that we think are fundamental, point-like, and indivisible today actually aren’t. Perhaps, if we go to high-enough energies and small-enough wavelengths, we’ll be able to see that at some point, between our current energy scales and the Planck energy scale, there’s actually more to the Universe than we presently know.”

Are the fundamental particles that we know of truly fundamental? Are they point-like entities, with no finite size, no internal structure, and no capacity to ever be split apart into smaller entities? According to the Standard Model, they are. But observationally, we know that the Standard Model isn’t all that there is. Moreover, we’ve got a long way to go (some 16 orders of magnitude) from our present experimental limits to the Planck scale, and what we think of as “fundamental” could undergo a revolution at any place, without any warning, if only we dare to look.

Right now, the particles we know of appear fundamental down to a limit of about 10^-19 meters, but it’s a long way down to forever. Here’s what we know today.

This Is How Physicists Trick Particles Into Go…

This Is How Physicists Trick Particles Into Going Faster Than Light

“Čerenkov radiation is such a remarkable phenomenon that when the first accelerated electrons, in the early days of particle physics in the United States, physicists would close one eye and put it in the path of where the electron beam ought to have been. If the beam was on, the electrons would produce Čerenkov radiation in the aqueous environment of the physicist’s eyeball, and those flashes of light would indicate that relativistic electrons were being produced. Once the effects of radiation on the human body became better understood, safety precautions were put in place to prevent physicists from poisoning themselves.

But the underlying phenomenon is the same no matter where you go: a charged particle moving faster than light moves in a medium will emit a cone of blue radiation, slowing down while revealing information about its energy and momentum. You still can’t break the ultimate cosmic speed limit, but unless you’re in a true, perfect vacuum, you can always go faster than light. All you need is enough energy.”

It’s true, you can’t go faster than light in a vacuum. But if you’re not in a vacuum, but in any medium like glass, water, or even rarefied air, you can absolutely exceed the speed of light there. Once you do, the forces of electromagnetism will slow you down, causing you to emit a spectacular form of radiation that emits a characteristic blue glow. This light is now deliberately created by the setup of clever physics experiments to measure everything from radioactive decays to ultra-elusive cosmic particles.

Come learn how physicists trick particles into going faster than light, and why this is such a useful technique for uncovering the secrets of the relativistic universe!

How Many Fundamental Constants Does It Take To…

How Many Fundamental Constants Does It Take To Explain The Universe?

“Our Universe is an intricate, amazing place, and yet our greatest hopes of a unified theory — a theory of everything — seek to decrease the number of fundamental constants we need. In reality, though, the more we learn about the Universe, the more parameters we’re learning it takes to fully describe it. It’s important to recognize where we are and what it takes, today, to describe the entirety of what’s known.

But we still don’t know everything, and so it’s also important to keep searching for a more complete paradigm. If we’re successful, it will give us absolutely everything the Universe has in it, including solutions to our current mysteries. The hope of many, but not a requirement, is that the Universe will wind up being simpler than we currently know. Right now, unfortunately, anything simpler than what’s been put forth here is too simple to work. Our Universe may not be elegant, after all.”

Think about everything that exists in our Universe. We have the four fundamental forces: gravity, electromagnetism, and the strong and weak nuclear forces. We have all the particles and antiparticles of the Standard Model; we have the bosons; we have the ways that particle behavior changes dependent on energy. We have hundreds of known composite particles and the ways that they interact, couple and decay. For everything that’s known, there are at least 26 fundamental constants required to explain the Universe on top of the laws of physics themselves, and still, they don’t give us everything.

Could there be a deeper explanation? Or are things only going to get messier from here? Here are the constants to describe what’s known so far!


Found this overpressured carbon piece

Ask Ethan: Could Dark Matter Not Be A Particle…

Ask Ethan: Could Dark Matter Not Be A Particle At All?

“If dark energy can be interpreted as an energy inherent to the fabric of space itself, could it also be possible that what we perceive as “dark matter” is also an inherent function of space itself – either tightly or loosely coupled to dark energy? That is, instead of dark matter being particulate, could it permeate all of space with (homogeneous or heterogeneous) gravitational effects that would explain our observations – more of a “dark mass”?”

When it comes to all the matter and radiation in the Universe that we know of, at a fundamental level, every bit of it is made out of particles. From photons to neutrinos to leptons and quarks, there’s a quantum of energy for every type of energy we know of. Except, that is, for dark energy, which appears to be inherent to space itself, and doesn’t have a particle counterpart. There’s no evidence for clumping, inhomogeneities, or changes in dark energy over time. Well, what about dark matter, then? Is it possible that the most elusive form of mass in our Universe isn’t a particle at all, but rather can be interpreted as some sort of function inherent to space itself? While it does need to clump, and drives the formation of galaxies and the other structure in the Universe, it doesn’t necessarily need to be particle-based in nature.

It could, in fact, behave as a perfect cosmological fluid! What are the alternatives, constraints, and how do we know? Find out on this week’s Ask Ethan!

Ask Ethan: What’s So ‘Anti’ …

Ask Ethan: What’s So ‘Anti’ About Antimatter?

“On a fundamental level, what is the difference between matter and its counterpart antimatter? Is there some sort of intrinsic property that causes a particle to be matter or antimatter? Is there some intrinsic property (like spin) that distinguishes quarks and antiquarks? What what puts the ‘anti’ in anti matter?”

Every particle that exists has an antiparticle counterpart, with some particles behaving as their own antiparticles. Every time a particle collides with its antiparticle, it can annihilate away into pure energy; every time two particles collide with enough free energy, they can create particle/antiparticle pairs. But the key is that there are a whole slew of quantum numbers that must be conserved, and conserving energy is just the start of the story. Not every particle is matter; not every antiparticle is antimatter. Only fermions can have that designation. In fact, every fermion is a matter particle, and every anti-fermion is an antimatter particle, while the bosons, regardless of their other properties, are neither matter nor antimatter. Why is that? Because there are only two quantum numbers that are relevant to the question of whether you’re matter or not: baryon number and lepton number.

How do these come together to put the “matter” in normal matter, and the “anti” in antimatter? Find out on this edition of Ask Ethan!

No, Melting Quarks Will Never Work As An Energy Source“In order…

No, Melting Quarks Will Never Work As An Energy Source

“In order to create a particle with a heavy quark (strange, charm, bottom, etc.) in it, you have to collide other particles together at extremely high energies: enough to make equal amounts of matter and antimatter. Assuming you then make the two baryons you need (two charmed or two bottomed baryons, for instance), you must then have them interact under the right conditions — fast and energetic, but not too fast or too energetic — to cause that fusion reaction. And then, at last, you get that ~3-4% energy gain out.

But it cost you over 100% to make these particles in the first place! They’re also incredibly unstable, meaning they’ll decay to lighter particles on incredibly short timescales: a nanosecond or less. And, finally, when they do decay, you get 100% of your energy back, in the form of new particles and their kinetic energies. In other words, you don’t get any net energy out; you simply get out what you put in, but in a lot of different, hard-to-harness ways.”

Nuclear fusion is often hailed as the future of energy, as it converts more mass into energy via Einstein’s E = mc^2 than any other reaction we’ve ever produced in large quantities. But even though the fusion of hydrogen into helium causes such a large energy release, it’s still less than 1% of the mass you begin with. On the other hand, a new set of simulations involving a recently discovered particle indicates that, by fusing charmed baryons with one another, you can produce a doubly-charmed baryon and get up to 4% of your mass converted into energy. While many are touting this as a potential game-changer, the reality is much more sobering. Nuclear fusion is promising not just for the large yield, but because its reactants are abundant and stable, because the energy outputted is easy to harness, and the reaction is controllable. “Melting quarks” offer none of these, and as such, will never work as an energy source.

Come get the science explaining why this new discovery is so interesting, but also why it isn’t going to deliver an energy revolution anytime soon!

Five Discoveries In Fundamental Physics That Came As Total…

Five Discoveries In Fundamental Physics That Came As Total Surprises

“It was quite the most incredible event that has ever happened to me in my life. It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you.”

It’s often said that advanced in physics aren’t met with “eureka!” but rather with “that’s funny,” but the truth is even stranger sometimes. Rather than the scientific method of: hypothesis, method, experiment, results, conclusion, revise, repeat, etc., many times throughout history, it’s been a series of surprise observations that have often led to our greatest leaps forward. When the speed of light was discovered not to differ when you moved with or against it, it was so revolutionary it was the only Nobel Prize ever awarded for a null result. When the gold foil experiment resulted in high-energy recoils, it surprised Rutherford so thoroughly it was the most incredible thing to ever happen to him in his life. The leftover glow from the Big Bang was discovered quite by accident; the neutrino was a crazy hypothesis that many abandoned; and the discovery of the muon, perhaps the most unexpected particle of all, literally was met with a cry of, “who ordered that?” from Nobel Laureate I.I. Rabi.

These five discoveries changed the course of physics forever, but they came as total surprises to practically everyone. Sometimes, the answer is in the place you least expect.

Break The Standard Model? An Ultra-Rare Decay Threatens To Do…

Break The Standard Model? An Ultra-Rare Decay Threatens To Do What The LHC Can’t

“Just by sitting around with a bunch of unstable atoms, waiting for them to decay and measuring the decay products to incredible accuracy, we have the potential to finally break the Standard Model. Neutrinos are already the one type of particle known to go beyond the original Standard Model predictions, with potential ties to dark matter, dark energy, and baryogenesis in addition to their mass problem. Discovering that they undergo this bizarre, never-before-seen decay would make them their own antiparticles, and would introduce Majorana Fermions into the real world. If nature is kind to us, a box full of radioactive material might at last do what the LHC can’t: shed light on some of the deepest, most fundamental mysteries about the nature of our Universe.”

Want to uncover the secrets to the Universe? Find out what particles and interactions there are beyond the Standard Model? The conventional approach is to take particles up to extremely high energies and smash them together, hoping that something new and exciting comes out. That’s a solid approach, but it has its limits. In particular, we haven’t seen anything new at the LHC other than the Higgs Boson, and might not even if we run it forever. But another, more subtle approach might yield heavy dividends: simply gathering a very large number of unstable atoms and looking for a special type of decay: neutrinoless double beta decay. If this decay actually occurs in nature, it would mean that neutrinos aren’t like the other particles we know of, but rather that neutrinos and antineutrinos are the same particles: Majorana particles!

What would all of this mean, and what would it teach us about our Universe? Find out about our simplest hope for going beyond the Standard Model today!

Nuclear Physics Might Hold The Key To Cracking Open The Standard…

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.