Daniel Carney

theoretical physics. measurement at the limits of quantum mechanics and gravity (and sometimes both).

[Daniel Carney @four_form]

Very inspiring. The universe remains full of mystery

[Quanta Magazine @QuantaMagazine]

Mysterious little red dots. Impossibly large black holes. Galaxies that shouldn’t exist. Since coming online in 2022, the James Webb Space Telescope has revealed a series of cosmic enigmas that challenge our very understanding of astrophysics. https://t.co/8bu0Wa35kn

[Sridhar Ramesh @RadishHarmers]

Wittgenstein passes over of this in silence.

[Daniel Carney @four_form]

@bcubeddd @arxiv https://t.co/kKzEYxBYMG

[Daniel Carney @four_form]

@PeterMorganQF I agree that "explain classically" is way too broad in general. That's why I use a very specific set of Hamiltonian models, one of which can be viewed as classical, and talk about excluding it

[Daniel Carney @four_form]

Can you "test the quantization of gravity" with gravitational wave experiments?

Last week I was asked for an overview on this question. This was a nice chance to spell out some details I usually have to trim, so I'm sharing the slides:

https://t.co/EbPas6aCJk

[Daniel Carney @four_form]

Butokuden, Kyoto.

[Daniel Carney @four_form]

@bcubeddd @NanoscaleViews I think doug is correctly interpreting the paper. They are using “ER=EPR” to literally mean that there is a physical spacetime wormhole connecting the proton and electron. Pretty different from the original meaning where the wormhole would be a dual description

[Daniel Carney @four_form]

Paper link: https://t.co/djB5vAmWWA

[Daniel Carney @four_form]

Cute observation, which can be summarized in two lines:

1. Nonlinear QM models can solve NP problems in polynomial time (Abrams & Lloyd, 1998)
2. Taking G_mn = <T_mn> at face value, the result is a nonlinear QM model.

However, modern "classical" gravity models do not obey 2.

[Daniel Carney @four_form]

So... yet another reason to not use G_mn = <T_mn> as a defining equation of matter coupled to gravity. But there are plenty of other "semiclassical" gravity models that, presumably, do not give polynomial time solutions of NP problems. Still have to kill those with experiment :)

[Physics Today @PhysicsToday]

Gravity is unique among the known fundamental forces: There is currently no experimental result that requires a quantum theory of gravity. Markus Aspelmeyer and @four_form explore what’s needed to identify elusive signatures and finally connect gravity to quantum mechanics.

https://t.co/R1i6mAWybN

[Daniel Carney @four_form]

Not sure if RIKEN is a national lab exactly, but it feels a lot like Berkeley Lab…

[ArtButMakeItSports @ArtButSports]

Hercules and Nessus, by Giambologna, 1599

[Daniel Carney @four_form]

@karch_andreas Rogan should invite you to the show now, it would be nice to see the contrast in public

[Daniel Carney @four_form]

As an American who has been in this specific competition for my entire life, the main result has been that my work is better precisely because I had to compete against the rest of the world for my jobs

Artificially restricting open competition is un-American to the core

[Lauren Chen @TheLaurenChen]

My hot take is that it's OK for Americans to not want to compete against the entire world for a job in their hometown.

[Daniel Litt @littmath]

@Noahpinion I think your commentary on this stuff would be improved by learning something about what professional mathematicians do.

[Daniel Carney @four_form]

https://t.co/XFas8mq6gD

[Daniel Carney @four_form]

"Why doesn't a charge sitting still on the surface of Earth radiate" has many good answers but this paper is my new favorite.

If the earth was big enough that the radiation zone of the charge was within the "approximately flat" local region, the earth would be a black hole 😎

[Daniel Carney @four_form]

@martinmbauer All true, but many of those effects can also be explained by classical or semiclassical radiation. To really nail it down, add sub-Poisson photocounting, Bell violations with light, entanglement in light-matter experiments…