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Is that theory or observation? My understanding is that we know it doesn't react electromagnetically with other matter because we (failed to) observe that behav

by Twisol 5y ago

Is that theory or observation? My understanding is that we know it doesn't react electromagnetically with other matter because we (failed to) observe that behavior, not because we expected it to behave that way a priori. If modified Newtonian (MOND) theories won out, the theory would explain this observation by saying that there was no matter there to begin with. If neutrino theories won out, the theory would explain this observation by saying that dark matter is electromagnetically neutral. But those are two entirely different theories, trying to explain the same observations, and trying to fill the hole in our currently accepted models in different ways. EDIT: Per a child comment, you might mean "theory" as "idea", as in "the [idea] is that it doesn’t react electromagnetically with other matter." In which case, yes!

kzrdude 5y ago
There seems to be a lot of evidence for dark matter, that's how I understand it as an outsider. What it means is that there is a lot of consistency in observations, things add up, to the dark matter theory. I usually agree with your understanding of dark matter/dark energy as placeholders for missing knowledge.
- Twisol 5y ago
  Ah; I think we might only be disagreeing on terminology at this point, then. A physical "theory" is a coherent model that makes testable predictions in its own right, as in the "theory of gravitation". A hypothesis is an explanatory idea, like dark matter. There's definitely lots of evidence for dark matter, yes~!
usgroup 5y ago
a priori is the wrong term because our physical theories are not a priori. Dark matter has lots of reasons to be assumed but a common one is that when we try to explain the gravitational effects of galaxies based on a quantification of observable matter, there is a huge shortfall. That creates a space for something with a gravitational effect that is unobservable otherwise. That many of the objects of our physics are theory laden is true, but that they are therefore “unreal” or merely an artefact of theory does not necessarily follow.

by Twisol 5y ago

kzrdude 5y ago

There seems to be a lot of evidence for dark matter, that's how I understand it as an outsider. What it means is that there is a lot of consistency in observations, things add up, to the dark matter theory. I usually agree with your understanding of dark matter/dark energy as placeholders for missing knowledge.

Twisol 5y ago
Ah; I think we might only be disagreeing on terminology at this point, then. A physical "theory" is a coherent model that makes testable predictions in its own right, as in the "theory of gravitation". A hypothesis is an explanatory idea, like dark matter. There's definitely lots of evidence for dark matter, yes~!

usgroup 5y ago

a priori is the wrong term because our physical theories are not a priori. Dark matter has lots of reasons to be assumed but a common one is that when we try to explain the gravitational effects of galaxies based on a quantification of observable matter, there is a huge shortfall. That creates a space for something with a gravitational effect that is unobservable otherwise. That many of the objects of our physics are theory laden is true, but that they are therefore “unreal” or merely an artefact of theory does not necessarily follow.