Andrew Jaffe

Parliament seems to understand that the cuts to particle physics, astronomy, and nuclear physics don’t make sense.

Andrew Jaffe: The Planck Satellite observes the Random Universe youtube.com/shorts/z8IzkiK… via @YouTube

You can hear me discuss my new book, The Random Universe, with my colleague Brian Keating on his excellent Into the Impossible podcast. yalebooks.yale.edu/book/978030025…

Is the Universe pre-determined or random? In this conversation, @defjaf dives deep into why the universe may be fundamentally, intrinsically random. Plus: Is inflation on life support? What's the truth behind the Hubble tension? Is cosmology is approaching the event horizon, limits beyond which humans can never know?

@CburgesCliff @WKCosmo I suppose that’s technically true, but I’m not sure it’s a useful way to describe anything which compares a local (more traditionally gauge-invariant) quantity with other quantities chosen on some hypersurface (e.g., overdensities, or anything defined by harmonic transforms).

@WKCosmo Agree. Scalars are gauge *co*variant as opposed to *in*variant. But still think observables are gauge invariant (even though I also agree we choose a gauge when measuring them in practice).

When field theorists talk about the concept of a gauge, they mean something slightly different than when relativists talk about a gauge. This sometimes leads to really wrong statements like "scalars (or obsevables) are automatically gauge-invariant."

@martinmbauer Except that Δ is absolutely horrible notation for the Laplacian.

Name an equation that looks crazy, but every physicist or mathematicians immediately knows it’s true.

@AnkerOfficial I am in Japan and would like to purchase a portable wall charger (like the 737 or 747). Which of your chargers feature interchangeable plug adapters? Is this information listed anywhere?

Nobel prize in physics for the development of machine learning techniques. Interesting choice — incredibly consequential (it lies behind large language models like ChatGPT etc), but arguably not “physics”. nytimes.com/2024/10/08/sci…

Running the @X iPad app on macOS has started crashing on launch for me. Anyone else? Any ideas? Bug or feature?

"The Bizarre Shape of the Universe" Watch this YouTube video about COMPACT (@CompactCollab) and our PRL paper on cosmic topology: youtu.be/xqDmTBa3nr4?si… Thanks a lot, Elizabeth Fernandez (@SparkDialog), Jade Tan-Holmes and Tom Groenestyn for creating such an incredible video!

@PenguinUKBooks Any plans for an ebook edition of Robert Caro’s The Power Broker now that one is available in the US?

@skdh Mathematics is an analogy.

If you want to understand modern physics -- or really any abstract ideas -- you have to take it for what it is and stop trying to understand it through something else like it. There isn't anything else like it. This is the problem with well-indended analogies like the rubber sheet for gravity or pairs of shoes for entangled particles or a spinning ball for spin or the like. They're all wrong and if you take them seriously they will just confuse you. Yes, it helps if you can read the maths. And I would argue that anyone can learn how to read it. (Using it is another thing.) But as a first step get over analogies. Gravity is a theory for the curvature of a four dimensional space-time and it's described by 10 non-linear coupled partial differential equations sourced by the stress-energy tensor. Then you need to know what properties space-time has and what curvature means and what's in the stress-energy tensor and so on. It's not super complicated and I am not joking. Fwiw, human psychology is considerably more complicated and you deal with that every day! x.com/QiaochuYuan/st…

12/ 📚🔬 We chat about Marc's paper with Wang & @defjaf called the Polarization Pursuers Guide. The paper presented the possibility of measuring B-mode polarization of the CMB experimentally, inspiring me to design the experiment called BICEP which led to @BICEPTWO & @BICEP_Keck.

Aha, the problem goes away when I turn on a VPN. But why?

@TripIt I can’t seem to access your services from the web or app right now:

@DScol @abigail_j_lee Seems like the bottom line is “underestimation of systematic errors” rather than “supports the Hubble tension story”?

Two new interesting H0 measurements on arxiv last night: arxiv.org/abs/2408.03660 (Boubel et al.). - and arxiv.org/abs/2408.03474 (Lee et al. - @abigail_j_lee). The first does new Tully-Fisher and gets high H0, the second does JAGB and gets lower. Interestingly, I think both support the hubble tension story after you unpack them. A wonky thread.

@joezuntz Congratulations!

It's very nice to be able to share that I've been promoted to Professor of Cosmology at the University of Edinburgh.

It is extraordinary that the USA gets treated to a dismantling of the Tory party orders of magnitude better than the tame efforts anyone dares attempt here. (And no, it's not the swearing that makes the difference - it's the accuracy of the attacks.)

Me, talking topology.

I sometimes forget how important R.E.M. were to me, for a very long time. pitchfork.com/news/watch-rem…