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BB84

@ BB84 @mander.xyz

Posts
11
Comments
92
Joined
2 yr. ago

  • vibes-based astrophysics

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  • It's a classic MEMRI TV meme. What MEMRI TV is would require a ..... "nuanced" explanation that I don't want to get into here. Look it up on Reddit or start a thread on !nostupidquestions@lemmy.ml

  • vibes-based astrophysics

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  • WIMP is only one model of dark matter. A favorite of particle physicists. But from a purely astrophysics point of view there is little reason to believe dark matter to have any interaction beyond gravity.

  • vibes-based astrophysics

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  • But it is a model we invented no? To explain the astrophysical and cosmological observations.

    Among all those observations, a commonality is that it looks like there is something that behaves like matter (as opposed to vacuum or radiation) and interact mostly via gravity (as opposed to electromagnetically, etc.). That's why we invented dark matter.

    The "it is unsuited" opinion in this meme is to poke at internet commentators who say that there must be an alternate explanation that does not involve new matter, because according to them all things must reflect light otherwise it would feel off.

    Once you believe dark matter exists, you still need to come up with an explanation of what that matter actually is. That's a separate question.

    (I'm not trying to make fun of people who study MOND or the like of that. just the people who non-constructively deny dark matter based on vibes.)

  • vibes-based astrophysics

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  • Particle physicists love the Weakly-Interacting Massive Particle dark matter model. But from a purely astrophysics point of view there is little reason to believe dark matter to have any interaction beyond gravity.

  • vibes-based astrophysics

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  • I'm still far from convinced about MOND. But I guess now I'm less confident in lambda CDM too -_-

    I'm inclined to believe it's one or many of the potential explanations in your second link. But even then, those explanations are mostly postdictions so they hold less weight.

  • vibes-based astrophysics

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  • MOND is a wonderful way to explain rotation curves but since then with new observations (bullet cluster, gravitational lensing, ...) MOND doesn't really hold up.

  • vibes-based astrophysics

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  • I've heard of something similar that is able to predict an effect of dark matter (the rotation curves), but AFAIK it couldn't match other observations (bullet clusters, etc.) correctly.

    Do you have a link for the model you're talking about. I'm curious.

  • vibes-based astrophysics

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  • This is a very fair take, but I'd say dark matter is harder to falsify, but not totally unfalsifiable.

    You can't see it, true. But what makes sight so special? We can't smell stars either. You just need to sense dark matter in some other way. Namely gravity! We have seen the way visible matter orbit, and that points to dark matter. We have seen gravitational lensing due to dark matter. Hopefully soon we'll observe gravitational waves well enough to sense dark matter around the regions the waves are being emitted from.

    Most individual dark matter models are falsifiable (and many have already been falsified) through non-gravitational means too. People have been building all sorts of detectors. The problem with this is that detectors are expensive and there are always more models beyond any detector's reaches.

  • OpenAI announces plan to transform into a for-profit company

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  • Okay that sounds like the best one could get without self-hosting. Shame they don’t have the latest open-weight models, but I’ll try it out nonetheless.

  • OpenAI announces plan to transform into a for-profit company

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  • Interesting. So they mix the requests between all DDG users before sending them to “underlying model providers”. The providers like OAI and Anthropic will likely log the requests, but mixing is still a big step forward. My question is what do they do with the open-weight models? Do they also use some external inference provider that may log the requests? Or does DDG control the inference process?

  • OpenAI announces plan to transform into a for-profit company

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  • Stop depending on these proprietary LLMs. Go to !localllama@sh.itjust.works.

    There are open-source LLMs you can run on your own computer if you have a powerful GPU. Models like OLMo and Falcon are made by true non-profits and universities, and they reach GPT-3.5 level of capability.

    There are also open-weight models that you can run locally and fine-tune to your liking (although these don’t have open-source training data or code). The best of these (Alibaba’s Qwen, Meta’s llama, Mistral, Deepseek, etc.) match and sometimes exceed GPT 4o capabilities.

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  • ur dada so buff he falls significantly faster than g

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  • even light can stop following null geodesics because the curvature can be too big compared to the wavelength

    Very interesting! How do you study something like this? Is it classical E&M in a curved space time, or do you need to do QED in curved space time?

    Also, are there phenomena where this effect is significant? I’m assuming something like lensing is already captured very well by treating light as point particles?

  • ur dada so buff he falls significantly faster than g

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  • So if I have a spherically symmetric object in GR I can write the Schwarzschild metric that does not depend on the radial mass distribution. But once I add a second spherically symmetric object, the metric now depends on the mass distribution of both objects?

    Your point about linearity is that if GR was linear, I could’ve instead add two Schwarzschild metrics together to get a new metric that depends only on each object’s position and total mass?

    Anyway, assuming we are in a situation with only one source, will the shell theorem still work in GR? Say I put a infinitely light spherical shell close to a black hole. Would it follow the same trajectory as a point particle?

  • ur dada so buff he falls significantly faster than g

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  • For the bowling ball, Newton’s shell theorem applies, right?

  • ur dada so buff he falls significantly faster than g

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  • Earth is in this case not an inertial reference frame. If you want to apply Newton's second law you must go to an inertial reference frame. The 9.81m/s/s is relative to that frame, not to earth.

  • ur dada so buff he falls significantly faster than g

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  • That is one very impressive feather.

    Restricting ourselves to feathers made by non-human animals

    🤔🤔🤔

  • ur dada so buff he falls significantly faster than g

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  • Newton's second law works in inertial frames. The acceleration of both objects would be the same in the inertial frame. But in the inertial frame, the earth would accelerate faster toward the object if the object was a bowling ball than if it was a feather.

  • ur dada so buff he falls significantly faster than g

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  • the original title was “your mom falls significantly faster than g”