370 | Daniel Akerib on a Faint Hint of Dark Matter

Sean Carroll (0:00)

Hello, everyone. Welcome to the Mindscape Podcast. I'm your host, Sean Carroll. You might have heard in the news, we're not up on the news here at Mindscape. We don't actually chase after every ambulance and try to fill you in on the latest wrinkle in scientific or other intellectual discovery, but occasionally, it's worth changing the rules a little bit, doing something a little bit different. So you may have heard that there was a press release out from the Lux-Zeplin experiment, or just the LZ experiment. This is an experiment deep underground looking for dark matter, looking for the occasional dark matter particle that will come into their detector, bump into a nucleus, and leave a signal.

The new result is, there's many experiments that have been doing this for quite a while. Now, they've seen an event that they can't explain, and we're going to dig into this for two reasons. One is, it might be the dark matter, and that would be very exciting. It's not at all super statistical significant right now. It's a little hint of a clue. It's absolutely not something you should get overly excited about, but it's also respectable. These are people who know what they're doing. They tried very hard to kill it. This is what good experimenters do when they get a weird signal, something they didn't anticipate or something that would be very exciting. They really put a lot of effort into figuring out, could it have been something else?

They can't figure out that it could have been anything else, even though it's only one event, it still sticks out like a sore thumb. I think it's worth getting on top of that, figuring out what might it be, why are we interested in this, that kind of thing. But the other reason is it is a good lesson in how science works. It's how things actually get done to find something and not know, whether or not it's the final answer or not. We get a lot of, in the modern age, nonsense out there about how science works, and it's good to really hear from a true expert, the process by which we gather data and then interpret the data and try very hard to understand what it could be, and all the different people working on this, and whether or not it turns out to actually be the dark matter. This is top-notch science in action, as it's supposed to be done. So today's guest is Daniel Akerib, who is a physicist at SLAC.

I think SLAC keeps changing its acronym, but it's the Stanford Linear Accelerator, is what it used to be. Anyway, it's the Particle Physics Laboratory, associated with Stanford. And Dan is someone I've known for a long time. He's been working on dark matter searches for a long time. There's different kinds of dark matter, as we'll talk about, different kinds of searches. He and his teams have been looking for WIMPs, Weakly Interacting Massive Particles. For a long time, WIMPs were the leaders, as the theoretical candidates for dark matter. They're not the only ones out there, but we've been looking for a long time and we haven't seen them yet. That doesn't mean they're not there. Maybe they're just out of reach. Maybe this is the first hint that we are seeing them. So I love it as an example of real science, of the care, the level headedness, the tentativeness, that real scientists have to go through every day. There's no answers in the back of the book. You can't hurry the process. You have to sit through it and be careful. So whether they get more data points, whether there are more events, and we figure out this is the dark matter, or whether it someday goes away, or whether it's just a mistake of some sort, all these are possible. We'll know it's good science in the meantime. We'll learn a lot. You folks who are listening here will be on top of what needs to be understood when more information comes in, both from this experiment and from other experiments doing similar things. So let's go.

Dan Akerib, welcome to the Mindscape Podcast.

Daniel Akerib (4:18)

Sean, it's great to be here. It's good to see you.

Sean Carroll (4:20)

It's been a long time. Dan and I have known each other for a long time, both when we were at different Midwest institutions, but now scattered to different coasts, but it's good to catch up again.

Now, you have devoted your life to looking for something that nobody has ever seen. So tell us a little bit about dark matter. What is it? Let's go very general here.

Daniel Akerib (4:42)