Washing through a sea of wimps: the search for dark matter in strange places
Meet the scientists searching for the universe's most illusive ingredient
So, here’s something I learned while making this podcast: Most of the matter in our universe is invisible and, so far, indetectable.
And another thing: Some people make it their jobs to go looking for it.
In episode six of How to Be Anything, we meet two scientists: One of them works one mile underground in a decommissioned gold mine in the mountains of South Dakota. The other works at a desk with his feet up. (OK, that was a bad habit, but he still has the desk.)
Both of them are looking for dark matter, the unknown substance that constitutes 85% of the material universe. One of them might have found it.
What is dark matter?
Turns out, we really don’t know. According to Professor Dan Hooper—our resident astrophysicist and cosmologist (not cosmetologist, different job entirely) in episode six, “How to Search for Dark Matter Underground and in Space”—we know a few things. That dark matter is…
Made of slow-moving particles
Relatively stable and inert
Not in the habit of radiating, reflecting, or absorbing light (that’s why they call it dark matter)
And that’s…about it
Why do we care if we find it?
Glad you asked! Lots of things could happen.
The discovery of different forms of matter births entire fields of science. In the 18th century, the discovery of gases gave us chemistry. In the 20th century, the discovery of the electron gave us quantum mechanics. It’s not unreasonable to think the discovery of dark matter might do the same. So…in some ways, you might think of it as a job creator.
And another: We could get a glimpse of what our universe looked like a fraction of a second after the big bang. 💥
Where do we look for dark matter?
Because we’re not sure exactly what dark matter is, scientists are looking for different things in different places: Underground, with dark matter detectors, like the LUX-ZEPLIN, they’re looking for one type of interaction. And in space, with devices like the Fermi Gamma-ray Space Telescope, they’re looking for another.
There are a few theories of what dark matter might be.
One is that they’re weakly interacting massive particles, or wimps. And as Gavin Cox, a research support scientist at the Sanford Underground Research Facility in Lead, South Dakota, tell us in episode six, “these are very small, very dense particles that are theorized to be distributed all throughout the galaxy. So that means our solar system and our planet is washing through this sea of wimps.” Gavin works with the LZ Dark Matter Detector, waiting for one of those wimps to pass through the earth.
Another theory says dark matter might be a little unstable, so if it decays, it could spit out gamma rays. Or, two particles might smash together and, I quote astrophysicist Dan Hooper, “visible stuff comes out.”
So…
So, we send telescopes into space.
When NASA’s Fermi Telescope sent back its first data in the late 2000s, scientists absolutely lost their minds and Dan Hooper and his colleague Lisa Goodenough went full geek. The plan was to rule out some theories about what dark matter could be—because, in “the dark matter game” (Hooper’s words, not mine) most of your work is just crossing ideas off the list.
But. But! There was a bump, and “most things in nature don’t make bumps.”
Was that…? Could it be…? Is it…dark matter?
This is where I tell you to listen to the episode and find out. Find us on Apple Podcasts, Spotify, and anywhere else you listen to podcasts.
Keep learning
Here’s a list of things mentioned in this episode that you would otherwise have to go Googling for:
Info about the Sanford Underground Research Facility
A diagram of the LZ Dark Matter Detector
Dan Hooper’s book on dark matter, Dark Cosmos: In Search of Our Universe's Missing Mass and Energy
Dan Hooper’s podcast, Why This Universe? (This episode about dark matter is particularly good primer)
Dan Hooper’s band, The Spectral Distortions
And if you would like to feel very unproductive, you can read more about Enrico Fermi, who, as “a youngster in Italy, Ph.D. not yet in hand, he taught himself the novel theories of quantum physics and relativity.” (What have I done today?)
Bye and thanks for listening!
—Emily