I'm a mathematical physicist who likes explaining stuff. Sometimes I work at the Topos Institute. Check out my blog! I'm also a member of the n-Category Café, a group blog on math with an emphasis on category theory. I also have a YouTube channel, full of talks about math, physics and the future.
Maybe you've heard the big news about LUX-ZEPLIN, the dark matter detector. They put 10 tonnes of liquid xenon in a tank, 1.5 kilometers down in a mine. The idea is if that if dark matter is made of weakly interacting massive particles, these might hit a xenon nucleus and make it emit some light.
They've been waiting for 280 days and they haven't seen anything interesting. That's the big news. 😕 They claim this rules out the possibility that dark matter is made of weakly interacting massive particles that are more than 9 times as heavy as a proton.
It must be somewhat discouraging doing this work. To paraphrase one of the team members: "we are the world leaders in not detecting dark matter". But it's good that people are trying. While you may have already decided physicists will never find dark matter, they have to actually look. In particle physics, you never discover a new particle until you do.
Alas, it's completely possible that dark matter is made of stuff that 𝑜𝑛𝑙𝑦 interacts gravitationally with other matter, so that we'll never find it with detectors like LUX-ZEPLIN, yet it still exists.
It's also completely possible that something other than dark matter - something we don't understand yet - is making galaxies spin faster than they should given the matter we see, and form earlier than they should given the matter we see, and so on. But while this is easy to say, it's incredibly hard to make up a theory that explains all these phenomena without dark matter! People are trying to make up new theories of gravity that do the job, but these theories have a lot of problems.
Maybe you've heard the big news about LUX-ZEPLIN, the dark matter detector. They put 10 tonnes of liquid xenon in a tank, 1.5 kilometers down in a mine. The idea is if that if dark matter is made of weakly interacting massive particles, these might hit a xenon nucleus and make it emit some light.
They've been waiting for 280 days and they haven't seen anything interesting. That's the big news. 😕 They claim this rules out the possibility that dark matter is made of weakly interacting massive particles...
@johncarlosbaez the fate of dark matter experiments. I once saw a cartoon by Sidney Harris of mounteners walking down a hole, saying: " Because it's not there"
@johncarlosbaez If I'm reading this chart from WP right, 9GeV/c2 mass cuts out WIMPs as explanation. Would it also detect composite/macroscopic DM, non-topological solitons?
I want to read this book: A Darwinian Survival Guide. Sounds like a realistic view of what we need to do now. You can read an interview with one author, the biologist Daniel Brooks. A quote:
...
Daniel Brooks: What can we begin doing now that will increase the chances that those elements of technologically-dependent humanity will survive a general collapse, if that happens as a result of our unwillingness to begin to do anything effective with respect to climate change and human existence?
Peter Watts: So to be clear, you’re not talking about forestalling the collapse —
Daniel Brooks: No.
Peter Watts: — you’re talking about passing through that bottleneck and coming out the other side with some semblance of what we value intact.
Daniel Brooks: Yeah, that’s right. It is conceivable that if all of humanity suddenly decided to change its behavior, right now, we would emerge after 2050 with most everything intact, and we would be “OK.” We don’t think that’s realistic. It is a possibility, but we don’t think that’s a realistic possibility. We think that, in fact, most of humanity is committed to business as usual, and that’s what we’re really talking about: What can we begin doing now to try to shorten the period of time after the collapse, before we “recover”? In other words — and this is in analogy with Asimov’s Foundation trilogy — if we do nothing, there’s going to be a collapse and it’ll take 30,000 years for the galaxy to recover. But if we start doing things now, then it maybe only takes 1,000 years to recover. So using that analogy, what can some human beings start to do now that would shorten the period of time necessary to recover?
I want to read this book: A Darwinian Survival Guide. Sounds like a realistic view of what we need to do now. You can read an interview with one author, the biologist Daniel Brooks. A quote:
...
Daniel Brooks: What can we begin doing now that will increase the chances that those elements of technologically-dependent humanity will survive a general collapse, if that happens as a result of our unwillingness to begin to do anything effective with respect to climate change and human existence?
"Stepping back a bit. Darwin told us in 1859 that what we had been doing for the last 10,000 or so years was not going to work. But people didn’t want to hear that message. So along came a sociologist who said, “It’s OK; I can fix Darwinism.” This guy’s name was Herbert Spencer, and he said, “I can fix Darwinism. We’ll just call it natural selection, but instead of survival of what’s-good-enough-to-survive-in-the-future, we’re going to call it survival of the fittest, and it’s whatever is best now.” Herbert Spencer was instrumental in convincing most biologists to change their perspective from “evolution is long-term survival” to “evolution is short-term adaptation.” And that was consistent with the notion of maximizing short term profits economically, maximizing your chances of being reelected, maximizing the collection plate every Sunday in the churches, and people were quite happy with this."
"Stepping back a bit. Darwin told us in 1859 that what we had been doing for the last 10,000 or so years was not going to work. But people didn’t want to hear that message. So along came a sociologist who said, “It’s OK; I can fix Darwinism.” This guy’s name was Herbert Spencer, and he said, “I can fix Darwinism. We’ll just call it natural selection, but instead of survival of what’s-good-enough-to-survive-in-the-future, we’re going to call it survival of the...
@johncarlosbaez "most of humanity is committed to business as usual" I'm not sure this is correct. Absolutely most of humanity scaled by their energy usage is, but this is a very different thing than most of humanity. Far fewer minds to change, much more entrenched opinions.
If our civilization collapses, extraterrestrial archeologists can look at this and be impressed. Three satellites following the Earth in an equilateral triangle, each 2.5 million kilometers from the other two. Each contains two gold cubes in free-fall. The satellites accelerate just enough so they don't get blown off course by the solar wind. The gold cubes inside feel nothing but gravity.
Lasers bounce between each cube and its partner in another satellite, measuring the distance between them to an accuracy of 20 picometers: less than the diameter of a helium atom! This lets the satellites detect gravitational waves — ripples in the curvature of spacetime — with very long wavelengths, and correspondingly low frequencies.
It should see so many binary white dwarfs, neutron stars and black holes in the Milky Way that these will be nothing but foreground noise. More excitingly, it should see mergers of supermassive black holes at the centers of galaxies as far as... the dawn of time, or whenever such black holes were first formed. (The farther you look, the older things you see.)
It may even be able to see the "gravitational background radiation": the thrumming vibrations in the fabric of spacetime left over from the Big Bang. These gravitational waves were created before the hot gas in the Universe cooled down enough to become transparent to light. So they're older than the microwave background radiation, which is the oldest thing we see now.
It's called LISA - the Laser Interferometric Satellite Antenna. And we're in luck: ESA has just decided to launch it in 2035.
If our civilization collapses, extraterrestrial archeologists can look at this and be impressed. Three satellites following the Earth in an equilateral triangle, each 2.5 million kilometers from the other two. Each contains two gold cubes in free-fall. The satellites accelerate just enough so they don't get blown off course by the solar wind. The gold cubes inside feel nothing but gravity.
The University of Pennsylvania is acting proud of Katalin Karikó now that she's won a Nobel. But they kicked her out of her research assistant professor job when she insisted on doing the work that won her that prize:
"She recalls spending one Christmas and New Year’s Eve conducting experiments and writing grant applications. But many other scientists were turning away from the field, and her bosses at UPenn felt mRNA had shown itself to be impractical and she was wasting her time. They issued an ultimatum: if she wanted to continue working with mRNA she would lose her prestigious faculty position, and face a substantial pay cut.
”It was particularly horrible as that same week, I had just been diagnosed with cancer,” said Karikó. “I was facing two operations, and my husband, who had gone back to Hungary to pick up his green card, had got stranded there because of some visa issue, meaning he couldn’t come back for six months. I was really struggling, and then they told me this."
"While undergoing surgery, Karikó assessed her options. She decided to stay, accept the humiliation of being demoted, and continue to doggedly pursue the problem. This led to a chance meeting which would both change the course of her career, and that of science."
Elsewhere she recalled:
“I thought of going somewhere else, or doing something else. I also thought maybe I’m not good enough, not smart enough."
She's now an adjunct in UPenn's neurosurgery department. Will they fast-track her for tenure now that she has a Nobel, or just live with the shame?
Both quotes here come from interesting stories. The first is from here:
The University of Pennsylvania is acting proud of Katalin Karikó now that she's won a Nobel. But they kicked her out of her research assistant professor job when she insisted on doing the work that won her that prize:
"She recalls spending one Christmas and New Year’s Eve conducting experiments and writing grant applications. But many other scientists were turning away from the field, and her bosses at UPenn felt mRNA had shown itself to be impractical and she was wasting her time. They issued an...
@johncarlosbaez if they gave people with “Nobel Prizes” tenure, there won’t be enough tenured positions left for very serious, academically rigorous people like Amy Wax.
Suppose you were trying to invent a bright orange powder that could easily dye clothes and be hard to wash off. Using your knowledge of quantum mechanics you'd design this symmetrical molecule where an electron's wavefunction can vibrate back and forth along a chain of carbons at the frequency of green light. Absorbing green light makes it look orange! And this molecule doesn't dissolve in water.
Yes: you'd invent turmeric!
Or more precisely 'curcurmin', the molecule that gives turmeric its special properties.
The black atoms are carbons, the white are hydrogens and the red are oxygens.
Read on and check out what pure curcurmin looks like.
(1/n)
Suppose you were trying to invent a bright orange powder that could easily dye clothes and be hard to wash off. Using your knowledge of quantum mechanics you'd design this symmetrical molecule where an electron's wavefunction can vibrate back and forth along a chain of carbons at the frequency of green light. Absorbing green light makes it look orange! And this molecule doesn't dissolve in water.
Gregory's Server
@johncarlosbaez These results must have them dazed and confused
@johncarlosbaez the fate of dark matter experiments. I once saw a cartoon by Sidney Harris of mounteners walking down a hole, saying: " Because it's not there"
@johncarlosbaez If I'm reading this chart from WP right, 9GeV/c2 mass cuts out WIMPs as explanation. Would it also detect composite/macroscopic DM, non-topological solitons?