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Will Kinney Profile picture
Will Kinney
@WKCosmo
Cosmologist, physicist, dirtbag mountain biker, expat Montanan, Copernican extremist. Part of the problem.
Oct 27 • 15 tweets • 2 min read
We shall measure stellar brightness logarithmically, and it will be called the "magnitude."

- Sir, will that logarithm be base 10, or based on Napier's constant?

Neither. It shall be of the base of the fifth root of one hundred. Image - and brighter stars will have larger magnitude?

No, it shall be the opposite.
Oct 21 • 30 tweets • 6 min read
Since it has come up, a thread on "negative energy," what it means, and why it's important in physics. 1/ Negative energy shows up all the time in classical physics, for example the potential energy in Newton's theory of gravity: 2/ Image
Apr 23 • 5 tweets • 2 min read

Image Having use for this image waaaay too often lately.
Feb 24 • 46 tweets • 10 min read
Bravo to the 22.9% who (correctly) concluded that the string connecting the rocket breaks!

Contrary to what is often taught, it is perfectly possible to handle accelerated reference frames in Special Relativity. This problem is a nice example. 🧵 1/ The rocket problem was first posed by John Bell (same guy as Bell's Theorem in quantum mechanics). The story is, he posed the problem to his colleagues at CERN, and (like the poll) most of them got it wrong!
Feb 7 • 16 tweets • 4 min read
Getting a lot of replies making various claims that this is not a quantum mechanical result, and you can't assign a velocity to electrons in atomic orbitals. Nonsense! This is ALL ABOUT quantum mechanics. Allow me to explain. 1/ Let's consider the simpler system of hydrogen first. The basic properties of the hydrogen atom are a consequence of the Heisenberg uncertainty principle relating the uncertainty of the radius of the electron in orbit to the uncertainty in its momentum, 2/ Image
Sep 28, 2023 • 20 tweets • 5 min read
The string breaks. Lots of responses to the poll, most of them wrong. Image
Jul 24, 2023 • 11 tweets • 2 min read
OK, saw Oppenheimer. A few reactions, no spoilers. 1/ Image Extraordinarily well done. Nearly flawless, IMO, and one of the most important and effective pieces of #scicomm I think I have ever seen.
Jul 21, 2023 • 43 tweets • 7 min read
A few words about this paper, which was a lot of fun to write. 1/N https://t.co/PRg3YHPvDr
Image Most of the heavy lifting on this project was done on a five-week visit to @iitmadras in Chennai in January, working with my awesome collaborators L. Sriramkumar and @suvashis_maity.
Apr 28, 2023 • 23 tweets • 4 min read
So what exactly is the Planck length? A thread. 1/ Let's start with the Heisenberg uncertainty principle, which we can write like this: 2/ Image
Mar 4, 2023 • 16 tweets • 2 min read
When I teach astronomy as a Gen Ed course, I include mythology and stories from a variety of cultures and traditions, because that is part of the history of the field, and the history of the development of the scientific method. 1/ Ancient and indigenous peoples had sophisticated and deep relationships with nature. Because they were smart humans.
Feb 26, 2023 • 25 tweets • 4 min read
It's starting to look like the problem of too many big galaxies too early for LCDM is likely to be a real thing. 1/ This, of course, is categorically NOT a problem for the Big Bang. It's about how structure formed in the late universe, starting a few hundred million years after the Big Bang itself. 2/
Feb 23, 2023 • 6 tweets • 2 min read
Wish I could tweet the smell. Image Veal liver in a brandy cream sauce with bacon and onion and snow peas tonight. Image
Dec 24, 2022 • 32 tweets • 5 min read
Since I'm in Pudecherry, India, let me tell you a bit about the world's unluckiest astronomer, one Guillaume Le Gentil. This is a crazy story, so pull up a chair. 1/ The year is 1760, and our man sets out from Paris as part of an international effort to observe the 1761 transit of Venus. 2/
Dec 2, 2022 • 4 tweets • 1 min read
GPT3 is really pretty good. Image Image
Dec 1, 2022 • 5 tweets • 2 min read
It's nice to see this from the editorial staff at @QuantaMagazine, but, with repect, the problem is not just the headline. Neither is it fair to lay this on @nattyover, who made a clear effort to accurately report what was in the paper. The people who should be taking 100% of the heat for this are the scientists who orchestrated a huge press blitz over wildly exaggerated claims in an embargoed paper. Everybody involved, including the theorists, should have known better, and probably did.
Nov 30, 2022 • 4 tweets • 1 min read
No they didn't. A better summary: Physicists created an entangled system of qubits in a quantum computer in a way that is well understood in conventional quantum mechanics, and some physicists have speculated that entangled particles are connected by wormholes.
Nov 18, 2022 • 5 tweets • 2 min read
This is just fucking amazing:

I know we've been repeating over and over that James Webb was a bigot, but it's not of any importance whether that was true or not. Just forget about that lie. Also, it doesn't matter if he was in fact a good man who was doing the right thing, we're going to smear him anyway, based on nothing. And you have to go along with it.
Sep 24, 2022 • 14 tweets • 3 min read
There were some questions about this, so a short thread. 1/ The solar system formed by the collapse of a primordial cloud of gas and dust. Which was very slowly rotating. 2/
May 12, 2022 • 23 tweets • 2 min read
So I was out riding singletrack this morning, a beautiful hot day. 1/ Just after a big stream crossing at the bottom of a steep, technical-ish downhill, I came across a dude by the side of the trail, fussing with his bike. 2/
Aug 29, 2021 • 22 tweets • 2 min read
Famous scientists on Twitter 1/N Bruno: constantly getting banned. 2/
Sep 8, 2020 • 28 tweets • 3 min read
Hi. The actual universe does not obey time translation symmetry, which means that energy is not conserved. Wow this blew up. People are really attached to energy conservation!

All right, all right. I'll try to explain. 2/