A wobble from Mars could be sign of dark matter
phys.org
phys.org
FTA: "'I think someone asked me what would happen if a primordial black hole passed through a human body,' recalls Tung, who did a quick pencil-and-paper calculation to find that if such a black hole zinged within 1 meter of a person, the force of the black hole would push the person 6 meters, or about 20 feet away in a single second. Tung also found that the odds were astronomically unlikely that a primordial black hole would pass anywhere near a person on Earth."
*Answer:*
Approximately 27 trillion kilograms—the black hole would need about 2.7 × 10¹³ kg of mass to exert tidal forces strong enough at 1 meter to tear off an arm. - This radius is much smaller than an atomic nucleus, so at a distance of 1 meter, the person is far outside the event horizon.
No, the black hole with a mass of approximately \( 2.7 \times 10^{13} \) kilograms would not evaporate quickly due to Hawking radiation. Even though this mass is relatively small compared to stellar black holes, such a black hole would have an extremely long evaporation time—*on the order of \( 5 \times 10^{16} \) years, which is about 50 quadrillion years*. This duration is vastly longer than the current age of the universe, which is approximately \( 13.8 \times 10^{9} \) years (13.8 billion years).
Only the tiniest black holes would have hawking temperature high enough to evaporate given the presence of the CMB
The apparent rarity of intelligent life might be a statistical matter of there being lots of opportunities for such life to arise, but also lots of hazards of random destruction.
... on reflection, while this might be intellectually satisfying, it's not particularly nice to contemplate.
Plus the rate at which a black hole can consume mass is proportional to mass/radius. If it's too small, it can only consume matter very slowly, which means the accretion disk would be cold and quiet.
I'd recommend watching a video from PBS Spacetime if you want to learn about it. They have several.
Dark matter has a roughly 50/50 track record.
https://www.earth.com/news/dark-matter-does-not-exist-univer...
Also no WIMPs were found so far.
https://www.newscientist.com/article/2445058-another-blow-fo...
Now we're doing Mars shots to prove it.
https://news.ycombinator.com/item?id=39726388
I'm not qualified to judge the merit of that theory, really... but my impression is that it doesn't have the explanatory power to be a great candidate.
Einstein and Planck just solved stuff, with a fraction of the talk and resources.
Now Physics seems to be so stagnant it's mostly an exercise in making descriptions for the things it's failing at, as though a problem can somehow match the value of a solution if you give it a cool name and talk about it enough.
Their ideas, solutions, and problems didn't come about from magic.
That's right. There is not yet a definitive answer on what dark matter is, just several theories. WIMPs, MOND, primordial black holes...
> Now Physics seems to be so stagnant
Crapping on modern physics for a lack of progress seems a popular thing amongst us lay people, but despite all the credit you give them (and that they deserve,) I doubt Einstein or Planck would have just intuited the right solution to dark matter.
That would be easy enough to explain away as an incomplete model, except we have observed galaxies which do fit our models. The only way to explain that is if those galaxies are missing this invisible mass. There's no other way to reconcile these observations.
How would you square these observations? Under our models of gravity, most galaxies behave as though they contain much more mass than what we observe. However, some behave exactly as Newton would predict. The misbehaving galaxies can be made to fit the model by adding mass in very particular locations, mainly as a halo or shell around the outside.
We can show how much mass and where it must be to make galaxies behave as expected. These calculations are the same for most galaxies with dark matter, and galaxies without dark matter require no correction. At this point we have two explanations: either gravity behaves radically differently in different places in the universe, or there's a new type of massive particle that we haven't discovered.
We know already that the standard model of particle physics is incomplete, and there are more particles to be discovered. We are also very confident that the laws of physics are the same throughout space and time, and we are very confident that our models of gravity are correct on large scales.
The simplest explanation that fits all available data is dark matter. Positing that there's a new type of massive particle that we haven't discovered isn't really a shocking revelation.
And use things like pi=3=1 and a whole bunch of other simplifications.
It’s a miracle it predicts anything at all.
Besides, this also ignores the fact that we observe galaxies both with and without dark matter. These galaixes have very different structures that cannot arise from the same physics unless we consider dark matter.
If the basic assumptions of your calculations are wrong it’s not surprising if your conclusions are as well.
Here a link for one of the simple explanations they didn’t take into account leading to wrong redshift measurements https://www.mdpi.com/2571-712X/7/3/41