Biggest Mysteries in Physics: Antimatter, Dark Energy & ToE - Don Lincoln | Lex Fridman Podcast #497

The brilliant thing was when Newton looked at that and he thought about, maybe the moon is falling, but it's missing the Earth. So what we had is that in maybe 1650, you had what we might call the laws of celestial gravity, the gravity that governs the heavens, and terrestrial gravity, the gravity that is here on Earth. Now, we don't think of it that way anymore. We think of it as just gravity. But at that time, that wasn't at all obvious. And in fact, if you look in the books, Newton's theory is Newton's law of universal gravity. The universal is there, and the reason is because he realized these two things that seemed to have nothing to do with one another were indeed one and the same.

Captures the conceptual leap of unification by reminding us that gravity wasn't always seen as one phenomenon — a model for how future unifications might feel.

Electricity equals magnetism. And that is a staggering concept, the fact that these two things, a lightning bolt and the magnet that holds your kids' art to the refrigerator, are one and the same... So I'll tell you about some more in a moment, but one thing that's kind of important because the goal is, of course, to unify everything. That if I could do what I want to do, I would have some unified theory that would explain all the behavior of all energy, matter, space, and time, which is a grand goal.

Frames Maxwell's electromagnetic unification as the template for the ultimate physics dream — a single theory describing everything.

This very fundamental digging into the laws of nature has spinoffs, and it has spinoffs— One of the big spinoffs is our entire technological society. Without being able to govern electricity, we'd still be farmers and shoemakers in cities... It's really a lovely thing to show how this digging into deep, fundamental, not understood, mysterious things can, a hundred or two hundred years later, transform the world.

A defense of fundamental science: today's seemingly useless curiosities are tomorrow's civilization-shaping technologies.

Different people moving at different speeds with respect to one another experience time differently, which is absolutely a mind-blowing concept. Now, most people think that Einstein then said, well, he invented spacetime... But that actual insight came from one of his teachers, a guy by the name of Minkowski, who looked at Einstein's equations. Minkowski was a little bit more mathematically inclined than Einstein, and he saw that if you look at the equations, you have basically one person's space and time equals some numbers times this person's space and time.

Credits Minkowski for the spacetime insight often attributed to Einstein, complicating the standard heroic narrative of relativity.

When I first encountered this, it's pretty freaking weird. It peaks the weird meter. But as you become more familiar with it... the speed of light, it's the speed of light through spacetime. Once you embrace that, that makes a whole ton of sense... I think that there is an ultimate speed isn't that shocking. It just simply says that it's a property of space... whatever space is, and we don't know what space is, but whatever it is, it has the capability of transmitting these things at that one speed through space or time, and everything else comes from our insisting that we keep space and time different.

Reframes the speed of light not as a bizarre limit but as a natural property of spacetime — a useful intuition shift.

There's a lot about science. There's, of course, knowing what went before. There is knowing the mathematics that allows you to figure out the implications of your theory. There is the discipline to argue with yourself and other people because most ideas are wrong. But then there's what you just described, that intuitive spark, and that is something that is very, very difficult to create. There's a reason that we venerate these people, is because it is an unusual feature, and most people only have that aha moment once in their lifetime, if they have it at all.

Dissects what makes a scientific genius — the rare combination of intuition, mathematical discipline, and ruthless self-critique.

The Higgs field permeates all of space. And here's the kicker, some particles interact with the field, and some particles don't interact with the field. The ones that interact with the field get mass, and the ones that don't interact with the field don't have mass... The universe cooled, and at a certain temperature, what happened is the Higgs field turned on. And at the moment it turned on, it gave mass to the weak force particles, did not give mass to the photon. So that's what we call electroweak symmetry breaking.

A remarkably clear explanation of how the Higgs mechanism gives particles mass and how mass itself 'turned on' early in the universe's history.

What particle accelerators do, among other things, is simply transform energy into particles. And so basically, any particle that doesn't exist in nature, we can make in this way... The converse goes true... You can take matter and antimatter and bring it together, and it'll make energy. It's the process can go both ways. Energy can make matter and antimatter. Matter and antimatter can make energy, and this is just true.

Strips E=mc² down to its operational meaning: accelerators are literally energy-to-matter conversion machines.

So these are absolutely ginormous detectors, and basically they're cameras, and what they can do is they can take pictures 40 million times per second. Now, all the data comes streaming off that detector, and we can't record it all... Of the 50 million possible collisions per second, the fast electronics and then the computers pick the thousand. And then we pass those through analysis software and hand them to the graduate students, and they pick through them, looking and finding the handful that are the next Nobel Prize.

A vivid description of the staggering data-filtering pipeline at the LHC that turns 40 million collisions per second into a tractable scientific search.

Now, if we had had another two years or maybe three years of running the Fermi accelerator, Fermilab would have discovered or ruled out, or in this case, it turned out, discovered the Higgs boson, 'cause it's a real thing. We would have found it without a question. But we didn't have enough data in July of 2012... So that's where we were two days before the LHC said, 'We got it.' That was July 4th, 2012.

A poignant insider account of how close Fermilab came to discovering the Higgs before CERN — a near miss in the history of physics.

So the reason they call it the God particle is this book by Leon Lederman, and if you read his book, he says, 'Well, you know, we call it the God particle, but we should call it the goddamn particle because it's been causing us so much trouble trying to find it.'... The real truth was the book was called 'The God Particle' because his publisher thought it would sell more copies.

Debunks the religious framing of the 'God particle' nickname with the actual mundane publishing-industry origin.

So I hold personally that there are rules that govern matter and energy, space, time, and they probably are rules that I don't know... I do believe that with sufficient time, technology, effort, we will be able to figure this all out. Now, this isn't a thing in my lifetime. It's not a thing in my grandchildren's lifetime or even their grandchildren's lifetime.

Lincoln offers a sober, multi-generational timeline for achieving a theory of everything — pushing back against optimism in the field.

Suppose that you were some, you know, Joe Australopithecus 2 million years ago or something in Africa, wandering around somewhere in Kenya... He would never predict sperm whales or kraken. He would never predict what it's like the bottom of the ocean is going north... we have a realm that we can study, and we can even predict to some validity what would happen if we go some distance away. But the farther away we go, the less and less our local prediction really represents the reality of those more distant times.

A powerful analogy explaining why extrapolating known physics by 15 orders of magnitude to the Planck scale is likely doomed to miss entirely new phenomena.

It's a lot like back in the 1940s when people started thinking about the meaning of quantum mechanics. And I wanted to do that when I was a kid in the '70s. But then when I went to grad school, I realized that people, very smart people, people smarter than me, had been working on that for most of their lives and made no definitive progress. And so you have to decide, as a scientist who wants to answer questions, do I really wanna take on a question that is so hard that it will not be answered in my lifetime?

Captures the deeply personal career calculus scientists face when choosing between profound but possibly unsolvable problems and more tractable ones.

The observation of gravity waves. And it was from two neutron stars orbiting and coalescing... astronomers saw the flash. Gravitational wave astronomers saw the ripples of space-time. It was 140 million light years away... and the two incidents, light and gravity, both arrived within 1.7 seconds of one another. And that tells you that gravity travels at the speed of light.

An elegant example of a fundamental physics prediction being confirmed across 140 million light years with extraordinary precision.

So in the Casimir effect, you take two metal plates, the parallel plates, and you put them near one another, very, very close... because these plates are close to one another, this puts a constraint on the wavelength of the particles that can occur between the two plates... the net effect is there are more virtual particles outside and less particles inside, and therefore you have a net pressure which would then push those two plates together. That is a prediction we've been talking about, and guess what? It happens.

A tangible experimental confirmation that 'empty' space is full of virtual particles — the vacuum is anything but empty.

Every two point three seconds, we would smash ten to the thirteen protons into a target, and we would get out ten to the eighth antiprotons... over the course of a day, we were able to create something like one hundred billionth of a gram... If you combine one gram of antimatter and one gram of matter together, the energy release is equivalent to the combined Hiroshima and Nagasaki explosions.

Concretizes both the staggering difficulty of producing antimatter and the staggering energy density it represents.

I like the idea of antimatter, you know, but the reality is the danger, not the obvious danger of weapons, but the danger of if you wanted to be in a ship run by antimatter, if it ever got loose, well, you would never know it. That would be that.

Captures the visceral practical danger of antimatter propulsion that fascinates sci-fi fans but constrains real engineering.

Einstein says that when you take energy, you make matter and antimatter in equal quantities... We only see matter. Where'd the antimatter go? And the answer is, we don't know. However, there are some ideas... somehow in the early universe, something made a very, very tiny asymmetry, so that for every billion, billion with a B, antimatter particles that existed in the universe, there were a billion and one matter particles. The billions canceled, annihilated, destroyed each other, and that extra one that's left over is us.

A breathtakingly clear framing of baryogenesis — that everything we see exists because of a one-in-a-billion asymmetry.

So at Fermilab, we have this idea which kind of turns things on its head, and it's not baryogenesis, it's leptogenesis... we're going to make a beam of neutrinos and another beam of antimatter neutrinos, and we're going to study the oscillation behavior of the two of them. And it is possible, it is unlikely, but it is possible that the two of them will oscillate at slightly different rates... I wish I could tell you I knew what the answer is, but literally nobody knows.

Frontline experimental physics: how neutrino oscillation experiments could reveal why the universe has any matter at all.

So back in the late 1990s, some astronomers were looking at the expansion rate of the universe... There were three possibilities... So they did the measurement, and what did they found? It was door number four. The universe was not only expanding, but the expansion was speeding up, and the only way that could happen, given that gravity slows it down, is there was a repulsive force, and the name we give to that repulsive force is dark energy.

A masterful, accessible retelling of one of the most surprising discoveries in modern cosmology.

Each wavelength adds a certain amount of energy, and if you add that all up, then you get a number, and that number is the rather embarrassing 10 to the 120 power times, that's a one with 120 zeros after it, bigger than the measurement of dark energy... there is very clearly something going on, something wrong, very badly wrong in the quantum field theory.

The worst prediction in physics — a 120-orders-of-magnitude failure that signals a deep gap in our understanding.

If space is increasing and space is quantized, and I don't know if it is, then maybe what's happening is space isn't stretching, but like little space particles are appearing as the space, you know, there's like bubbles of space appearing, and each bubble contains a certain amount of dark energy... it seems to me that this is leaning towards the idea that, A, it's a property of space, B, space is quantized, C, as space is expanding, little quanta of space are appearing, and D, each one of those quanta has a certain amount of energy associated with it.

A speculative but evocative picture: dark energy as evidence that space itself is quantized into discrete bubbles.

If there were no dark matter, you would see a cluster of galaxies, cluster of galaxies, a big gas cloud in the middle... If, however, dark matter is real, the galaxies pass through one another, the cloud stops, dark matter doesn't interact with the cloud, so it passes through. In that case, you would expect to see the distortions where the galaxies are. And that's what we see. So that is strong evidence in my mind. The Bullet Cluster is strong evidence that dark matter is a real thing.

A crisp explanation of why the Bullet Cluster is the smoking gun that pushed many physicists from modified gravity toward real dark matter.

I grew up a poor kid in the boondocks. Great parents, but not ones that could guide me terribly academically, but very very nurturing... science fiction is good for fostering imagination... there were lovely science communicators that were popular in the 1970s, Isaac Asimov, Carl Sagan, a guy by the name of George Gamow. They wrote books about science aimed at a layperson.

A reminder of how popular science writing creates scientists from unlikely places.

I would, from Monday through Saturday, I would be at the lab voluntarily because I wanted to be from eight AM to midnight... there is absolutely nothing more fascinating to me than having a hard problem and figuring it out... trying to measure something and having it not work just kinda ticks me off, and I am not going to let the universe in my lab or whatever beat me... because it's just you can't imagine not knowing the answer.

A vivid portrait of the obsessive drive that distinguishes working scientists — useful for anyone choosing a vocation.