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Daniel Carney

@fourform.bsky.social
74 followers 15 following 14 posts

theoretical physics. measurement at the limits of quantum mechanics and gravity (and sometimes both). Scientist @ Berkeley National Lab. qquest.lbl.gov/~carney

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Daniel Carney @fourform.bsky.social · 27/03/2025
If you want to hear me ramble about quantum noise and cosmic neutrinos, gravitational waves, and axions over zoom, this is tomorrow 4pm ET: sites.google.com/view/hepastr...
sites.google.com
HEP/Astro Results Forum
Our mission is to host in-depth and unbiased overview talks on recent experimental/observational results of interest, given by experts in the field, to a broad audience of particle physicists and astr...
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Daniel Carney @fourform.bsky.social · 27/02/2025
Probably head first!
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Daniel Carney @fourform.bsky.social · 26/02/2025
The obvious future direction is to figure out how to get a relativistic model -- i.e., recover general relativity rather than just Newton's law. Can this be done? TBD...
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Daniel Carney @fourform.bsky.social · 26/02/2025
In brief: the models have free parameters. In some regimes, the emergent gravitational interaction is indistinguishable from the usual picture involving gravitons. But in other regimes, the thermal fluctuations are large, and you can look for this in experiments.
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Daniel Carney @fourform.bsky.social · 26/02/2025
The basic idea is like two pistons being pushed around by an ideal gas. In our model, the pistons are massive objects, and the gas is the collection of thermalized qubits/oscillators. This is mostly a proof-of-concept construction, but the phenomenology is really interesting, and probably general.
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Daniel Carney @fourform.bsky.social · 26/02/2025
To do this you have to make a detailed microscopic model. In ours, there's a bunch of qubits or oscillators, and the frequencies of these depend on where massive objects are. You can engineer this so that if the qubits are thermalized, this frequency dependent coupling gives a 1/r^2 force.
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Daniel Carney @fourform.bsky.social · 26/02/2025
Jacobson and Verlinde famously suggested that gravity could come from some kind of thermal or "entropic" interaction. But their proposals were basically classical; they don't give enough details to figure out what happens when quantized matter couples to gravity. Our goal was to figure this out.
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Daniel Carney @fourform.bsky.social · 26/02/2025
People tell me that the technical discussion here is better than twitter these days. So let me try that out. Here's a sort of explainer on the paper:
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Daniel Carney @fourform.bsky.social · 26/02/2025
Gravity could come from gravitons, like light comes from photons. Or maybe, like sound waves in a gas, it could come from the entropic dynamics of some microscopic thermal system. But could that really work? And could it be tested? We think so. arxiv.org/abs/2502.17575
arxiv.org
On the quantum mechanics of entropic forces
It was conjectured thirty years ago that gravity could arise from the entropic re-arrangement of information. In this paper, we offer a set of microscopic quantum models which realize this idea in det...
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Daniel Carney @fourform.bsky.social · 28/01/2025
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Daniel Carney @fourform.bsky.social · 09/12/2024
Almost forgot to cross post 😅
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Daniel Carney @fourform.bsky.social · 09/12/2024
Could gravity be "fundamentally classical"? Akira Matsumura and I analyzed Oppenheim (@postquantum.bsky.social) et al.'s proposal. tl;dr: A. it appears to have Lorentz-covariant scattering B. 2—>2 scattering differs at O(1) from the usual Rutherford/Newton answer arxiv.org/abs/2412.04839
arxiv.org
Classical-quantum scattering
We analyze the framework recently proposed by Oppenheim et al. to model relativistic quantum fields coupled to relativistic, classical, stochastic fields (in particular, as a model of quantum matter c...
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Daniel Carney @fourform.bsky.social · 02/12/2024
I know. It's painful to me
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Daniel Carney @fourform.bsky.social · 02/12/2024
Look upon my TikZ, ye mighty, and despair.
small mass scattering on a large mass
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