3 ms·

There's a lot more to it than galaxy rotation curves. https://en.wikipedia.org/wiki/Dark_matter https://en.wikipedia.org/wiki/Dark_matter is worth a read, espe

by mkl 4y ago

There's a lot more to it than galaxy rotation curves. https://en.wikipedia.org/wiki/Dark_matter https://en.wikipedia.org/wiki/Dark_matter is worth a read, especially the Observational Evidence section. Also, general relativity has had considerable predictive success, so replacing it with something else that works the same in some situations but differently in others seems more complicated than "there's mass here in some form we don't understand yet", though people have of course tried to find such replacements. Physicists have been trying all the hypotheses they can think of and dark matter currently fits the evidence best, they didn't jump straight to dark matter or fixate on it without considering anything else.

Beldin 4y ago
> general relativity has had considerable predictive success, so replacing it with something else that works the same in some situations but differently in others seems more complicated than [...] First: you're very correct - we shouldn't expect an easy solution. Second: precisely the same argument applies to Newtonian gravity. It was phenomenally successful. The mismatch between observations and its model were more easily explained by lack in observations - and they were! We found Neptune because of that! That role (of plugging holes in observations) is currently being played by dark matter. So chances for dark matter existing in some form are good from a historical perspective. On the other hand, from that same perspective, chances of gravity theory being slightly(1) updated for extreme cases are also good. (1) "slightly" in the sense that the difference with the current theory, GR, would be nil or negligible in most cases.
the__alchemist 4y ago
>general relativity has had considerable predictive success, so replacing it with something else that works the same in some situations but differently in others seems more complicated than "there's mass here in some form we don't understand yet", though people have of course tried to find such replacements. Do the models use GR? My understanding is that they make the assumption that Newtoninan gravity models are sufficient.

by mkl 4y ago

Beldin 4y ago

> general relativity has had considerable predictive success, so replacing it with something else that works the same in some situations but differently in others seems more complicated than [...] First: you're very correct - we shouldn't expect an easy solution. Second: precisely the same argument applies to Newtonian gravity. It was phenomenally successful. The mismatch between observations and its model were more easily explained by lack in observations - and they were! We found Neptune because of that! That role (of plugging holes in observations) is currently being played by dark matter. So chances for dark matter existing in some form are good from a historical perspective. On the other hand, from that same perspective, chances of gravity theory being slightly(1) updated for extreme cases are also good. (1) "slightly" in the sense that the difference with the current theory, GR, would be nil or negligible in most cases.

the__alchemist 4y ago

>general relativity has had considerable predictive success, so replacing it with something else that works the same in some situations but differently in others seems more complicated than "there's mass here in some form we don't understand yet", though people have of course tried to find such replacements. Do the models use GR? My understanding is that they make the assumption that Newtoninan gravity models are sufficient.