I've been tweeting a bunch of articles and threads about the #gminus2 result -- a possible indication of ✨ NEW PHYSICS ✨ coming from @Fermilab! Check my timeline for details, but I'll give a very brief and simplified summary here...
An experiment at @Fermilab is measuring a property of muons -- subatomic particles similar to electrons, but heavier -- to try to determine if our current understanding of particle physics is correct or not. The experiment hinges on the fact that muons are a tiny bit magnetic 🧲
The "Muon g-2" experiment measures how muons spin around and how that spin wobbles when they're sent around a circular track in the presence of strong magnetic and electric fields. That depends on how the muon spins and its "g-factor", related to its magnetism.
The muon's g-factor should be a number close to 2. It's calculated to be a LITTLE different from 2 because of a weirdness of quantum physics. Turns out empty space is full of a kind of roiling quantum energy in the form of "virtual particles" that pop up and vanish all the time.
Virtual particles interacting with the muon very slightly tweak its g-factor by an amount that depends on how many of those particles exist and how they interact with the muon. If we calculate the g-factor carefully, and then measure the muon's behavior, we can test the theory.
The upshot of the #gminus2 experiment is that the theory calculations of the g-factor and the experimental results DO NOT AGREE, to a level of certainty that ALMOST reaches the threshold of what particle physicists would call a "discovery" (but not quite).
What does it mean that the theoretical prediction doesn't match @Fermilab's experiment? It *might* mean that there are new particles roiling around in the quantum foam that are NOT included in our Standard Model. Which could mean we can replace it with a new & better theory!
If we have FINALLY found clinching proof that the Standard Model of Particle Physics has a big hole in it, that might point us to new theories that could rewrite how we think about the forces of nature and the fundamental structure of the cosmos. It would be a REALLY big deal!
There's a caveat, which is that a NEW theoretical calculation using supercomputers and a different method (also published today!) gives a g value that just barely AGREES with the experimental result! So both theorists and experimentalists are working hard to figure out what's up.
Q: Does this have anything to do with the LHCb news two weeks ago? That also involved muons...🤔

A: We don't know! Both could be hints about new physics beyond the Standard Model -- specifically, both could tell us new particles exist! -- but that's about all we can say for now.
Q: How will we figure out *for sure* if #gminus2 is showing us new physics?

A: We're already getting more data. The result announced today was just from the first 6% of the data the Muon g-2 experiment will produce. And theorists will keep grinding away, too! Stay tuned...

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More from @AstroKatie

8 Mar
New guidelines from the CDC for what might be okay for fully vaccinated people: cdc.gov/coronavirus/20…

Note: Dr. @RWalensky emphasized during the White House press conference that this is the best guidance RIGHT NOW but may change as conditions change and the science develops.
New CDC guidance:

"Fully vaccinated" (FV) = at least 2 weeks after final vaccine dose

* FV people can hang out in small groups with each other without masks

* FV people can hang out in small groups with LOW RISK unvaccinated people

* Non-essential travel still discouraged
The reason they're not saying fully vaccinated people can "just go out and do whatever" is partly because vaccines aren't 100% effective and partly because being vaccinated might not always prevent you from carrying the disease to others. (This is still being studied.)
Read 4 tweets
5 Mar
This is an amazing optical illusion — caused by atmospheric conditions over the water bending light rays to make it look like the ship is above it. This video has a nice explanation (especially the bit starting around 1:20) . #FataMorgana
The proper term for this is “superior mirage” or “superior looming mirage” but I have seen the term “fata morgana” used for a similar phenomenon also caused by weird kinds of light bending over the ocean.
More on superior mirages from @iansample. theguardian.com/science/2021/m…

Rather than "optical illusion" it might be better to call this an "optics illusion." Your brain is processing visual information correctly, it's just that the light deflection makes that information unreliable!
Read 5 tweets
4 Mar
Here’s a long-ish excerpt from my book where I talk about THE BIG RIP, one possibility for the end of the universe. (More likely is a Heat Death, caused by endless accelerated expansion, which *doesn’t* rip things apart. But a Big Rip would be fun too.) americanscientist.org/article/tearin…
I just saw a clip of Neil deGrasse Tyson on the Late Show saying that the Big Rip is likely coming and that it’s the necessary result of endless accelerated expansion, neither of which is true! So, see above for clarification.
If you’re interested in reading about what cosmologists are discovering now about how the universe might end, check out my book, “The End of Everything (Astrophysically Speaking)”! It’s accessible and comprehensive and has lots of funny footnotes astrokatie.com/book
Read 4 tweets
19 Feb
A thing a lot of people don't seem to be aware of is that the proportion of astronomers who believe there is alien life of some sort in the universe is almost 100%. It's just the proportion who think they've *dropped by* that's almost 0.
I had a radio interview recently where the host started out all challenging saying "It's UNTHINKABLE there isn't other life out there in the cosmos!" and I was like, "yeah, pretty much" and I think he was not really prepared for that
What we know is that we find life in just about every environment we look for it on Earth, wherever there's some amount of liquid water -- sometimes even just ice. And we know there is water on other worlds. And there are a LOT of other worlds. So: life seems likely to be common!
Read 4 tweets
7 Feb
Watching the snow fall outside and thinking about terminal velocity, and how much less peaceful this whole scene would look without air resistance. ❄️💥
Terminal velocity is the final speed something reaches when falling through a fluid (like air). The force of gravity accelerates the thing, and air resistance slows it down (in proportion to the square of the speed), so at some point those things balance and it stops speeding up.
Terminal velocity for a raindrop is around 9 meters/second. For a snowflake it’s generally closer to 2 meters/second, depending on the size and fluffiness of the flake. (Some formulae here hyperphysics.phy-astr.gsu.edu/hbase/airfri2.…)
Read 4 tweets
1 Feb
Reporting on non-mainstream ideas in science is often skewed on either side, presenting them as either rare/revolutionary or totally suppressed.

In practice, there are a ton of people working on ideas their colleagues look at & say "eh, a bit niche" that might/might not pan out.
We don't invest en masse in the fringe ideas unless they pass enough rigorous tests to become the new consensus, but no one is saying "you can't publish on that." The vast majority of papers on ALL topics are ignored; the more extraordinary the claim, the more evidence it needs.
Not sure why I’m going on about this so much lately. I just think it’s important for people to know that in between all the big flashy results there are a bunch of us just chugging along trying all different things (and getting excited or not) and that’s good and normal science.
Read 5 tweets

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