Daniel WhiteSon: Particle PHysicist
"Is string theory a good contender for a deeper, more fundamental explanation, the idea that all 12 particles in the standard model are just the products of tiny vibrating strings?"
"I’d say string theory is a beautiful piece of mathematics, but it’s not science. Science requires falsifiability and string theory is at a level so tiny that we have no way to probe it. There are many beautiful mathematical theories that are not theories of nature and have been disproven and tossed aside even though they were gorgeous. So we don’t know whether string theory is just beautiful mathematics in the abstract or if it represents the way things really work."
"Are there any macroscopic manifestations of string theory? Even if we can’t look at strings, couldn’t we use it to make testable predictions at the subatomic level?"
"That’s the goal, but nobody’s devised an experiment at the subatomic or macroscopic level that would give you a different answer if string theory were true or false. For example, classical physics gives very very precise answers for baseball and cannon ball trajectories, but we know that it isn’t true in any fundamental way because it excludes quantum mechanics. And so you can't test quantum mechanics by playing a game of pool and measuring the balls very precisely. In the same way, you can’t test string theory with particle colliders. Not yet, not until we build a collider the size of the solar system or someone figures out a way to more directly connect string theory to the macroscopic world. But it’s gorgeous. I hope it’s true."
"We recently wrote an app that turns your smartphone into a particle detector."
"How does it do that?"
"Well, the camera in your smartphone has a lens, and behind the lens is a CMOS device which is basically a square of silicon, and the silicon is divided up into tiny cells, each one for a pixel, and each pixel is sensitive to light. The device collects light, turns it into electrons, and then measures the current. But it’s not just sensitive to light, it’s also sensitive to particles from space, cosmic rays, and we use the same technology to detect particles at the Large Hadron Collider. We realized that every phone contains this little CMOS device along with GPS, WIFI, and a little computer, so we wrote an app that turns your phone into a particle detector. And then we thought, 'That’s cool, but can we do real science with this?' So we did a calculation. How many people would have to run the app to build a cosmic ray telescope the size of the planet, and our calculation said about a million people."
"Only a million!?"
"Only a million! I know, only, right? We didn’t know if the answer was going to be a trillion or a hundred, so a million phones, that’s not bad, especially because there are 3 billion devices out there. So we wrote the app and people seem excited. 100,000 people signed up in the first two weeks."
"What will do once you get a million people to download the app?"
"There’s really interesting questions. Where are the cosmic rays coming from? We see particles at very very high energies, a million times more energetic than the particle collisions we make at the Large Hadron Collider. There’s something out there in universe capable of creating particles at super duper high energies, more energetic than anything we know about, and it’s shooting particles at us. The problem is these particles are really rare, about one per square kilometer per hundred years, so seeing them is hard. You need a detector that either runs for a very long time or is really big. So we thought, 'Can we build an Earth-sized detector with smartphones and see where these particles are coming from? Are they everywhere in the sky? Are they all coming from one planet as if someone was sending us a message?' A recent paper suggested that they may be pollution from an alien solar-system-sized particle accelerator. I read another paper a few weeks ago suggesting that the entire universe is a simulation inside a massive computer and that we could figure this out by looking at the high energy cosmic ray spectrum. I don’t understand the details, but wow, that’s crazy. We could measure these cosmic rays at a rate nobody’s seen before and gather a lot of data. Plus, in astronomy, every time you build a new kind of instrument, you find crazy stuff. Build a new kind of telescope, point it into space, just wait, and you’ll see some bizarre things.
Also, this is fun for us because I usually work on a huge collaboration at the Large Hadron Collider, and every time I have a paper, there’s like 3000 authors in alphabetical order because that’s how many people it takes to build a 10 billion dollar science experiment. But it costs 0 dollars to create a great telescope with smart phones and it’s totally under our control, and we have no idea whether it’s going to work."
"100 years ago, people thought physics was mostly figured out and universe was like a big watch, and once you knew the rules and the positions of everything, time would just march forward deterministically. That’s a little scary if you believe in free will because that sort of makes it impossible. But bring in quantum mechanics and now the universe looks completely different because there’s a fundamental raw randomness at the lowest level. That’s a bit scary because the universe is completely different from how we understand it. Although quantum mechanics is now associated with a whole swath of quacks, it brings up a lot of questions about free will and consciousness. For example, you cannot describe the universe without the presence of a conscious observer. Observation of the data changes the outcome of the experiment. It’s bizarre."
"It’s interesting that almost everything that is fundamentally true about the universe is absent from our common sense and is completely counterintuitive."
"I mean, our intuition is designed for the scale of our experience, about 1 meter length, about room temperature, about 1 m/s. And at different speeds and time scales, things work completely differently. But at every scale, amazingly, you can describe the emergent phenomena with a set of fairly simple rules. Like, why is it possible to come up with classical physics? Why isn’t classical physics hopelessly complicated because, in the end, you have to integrate over a bajillion tiny particles all doing crazy quantum mechanical things? Why is it possible to ignore all of that and create a simple set of rules that mostly work? You can do physics of galaxies and brush over entire solar systems, approximating them away, and it works! Physics at the tiniest levels also works. The trick is, can you connect these different scales? Is it even possible for a single theory to unify every scale? I don’t know, but it’s amazing to me that the universe seems to follow rules and that those rules are discoverable by us. It’s a pretty amazing world we live in."
"We’re trying to answer some very basic questions. What is the universe made of? What are the basic building blocks of everything? Our hope is that the answer is pretty simple, but the universe is very complicated."
"What would you say to people who view the standard model as a list of particles with little explanatory value?"
"If I asked you what the universe is made out of and you answered with a list of everything in the universe, it would technically be correct but totally unsatisfying. A list of everything would not give you any insight, but the list becomes interesting once it’s simplified, once we describe everything with a small number of things. So I would say it’s a huge step forward from an infinitely long list to a list of 12 particles in the standard model. That’s pretty impressive. However, we also know that the standard model is not the final answer because organizing that list of particles produces patterns and weird things we don’t understand. When you find patterns and various emergent phenomena in the periodic table, they're indicators of a deeper, more fundamental phenomena, electron orbitals. In the same way, we see patterns in our table of fundamental particles we don’t understand and we hope they’re indicators of a deeper, more fundamental theory we haven’t yet figured out."
"You’re involved in animated comics. How’d that happen?"
"When Google put out Chrome, they made a comic describing the development of the browser, and I thought it was a really nice way to convey something technical to a large audience. So I thought, can I do that for physics? And of course, I’m a fan of Jorge Cham (creator of PHD comics) as almost everyone in academia is, so my wife suggested, 'Why don’t you email Jorge Cham and see if he’s interested?' I thought that was sort of like calling up Brad Pitt and saying, 'Hey, would you like to do a movie with me?' But he responded right away and thought it was interesting, so we got together, talked about it, and that’s how the comic came to be."
"So this is an ongoing thing."
"Yah, we’re working on another one right now about our crazy mad scientist smart phone project."
"Can the universe be built out of different combinations of one or two little objects? We’re trying to answer this question by breaking things up, looking inside them, and figuring out what they’re made of. I work at the Large Hadron Collider, a 33 km tunnel just outside of Geneva, Switzerland. Every 25 nanoseconds, we shoot protons one way and protons the other way and, at some point around the ring, they collide creating locations ofreally high energy density. And 1 in a trillion times, something interesting happens. You create a new kind of particle or observe a new kind of force or something crazy. Most of the time, nothing very interesting happens. Two protons come in, two protons go out. Yawn."
"The Large Hadron Collider was launched in 2008 and the Higgs Boson was discovered in 2012, so it took 4 years of continuous collisions to discover it?"
"Well, it wasn’t running for a year because part of the machine blew up and we had to repair it, and then we ran for a year on lower energy, so it was really the last year of data that was critical to finding the Higgs Boson."
"In laymen’s terms, please explain the significance of discovering the Higgs Boson."
"There are two different things, the Higgs field and the Higgs particle. The Higgs field is the important bit. It’s an idea from Peter Higgs in the 1960s; he imagined that the universe was filled with an invisible field we hadn’t yet detected (and by field, we mean something with energy at every place in the universe) and this field had the bizarre property of interacting with things to give them inertia. So if this field interacts with a particle very strongly, that particle will be hard to speed up and slow down. And that effect, giving something inertia, is what we call mass. So this bizarre field that fills the universe is responsible for giving mass to all particles and the Higgs boson is evidence, a prediction, of that field. Sometimes, the field will have a local bit of energy and a boson will pop out."
"Let me try to wrap my head around this. The Higgs particle is concentrated energy."
"Mhm. It’s an excited state of the Higgs field."
"That excited state produces a particle and that’s what you observed in the collider."
"Every particle is an excited state of a field. Our modern view of particles is less like little bits of matter, a d more like excited states of field."
"So how is this analogous to say, an electron and an electromagnetic field?"
"An electron is not an excitation of the electromagnetic field. An excitation of an electromagnetic field is a photon, but there’s another field, a leptonic field, of which the excitation is an electron."
"So there’s kind of a hierarchy of fields and particles where excitations of fields produce particles and particles produce other fields."
"Mhm. Like, how do two electrons repel each other? How does that actually happen? Well, you can say that electrons produce electromagnetic fields, that’s true. And because excitations of the electromagnetic field are photons, you can also say that electrons pass photons back and forth. That’s how electrons repel each other, when one passes a photon to the other one, sending it momentum and kicking it away. That’s actually how it works."