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Honest question. If the concept of dark matter flows from our current understanding of gravity, and gravity is so admittedly poorly understood, how confident a

Honest question. If the concept of dark matter flows from our current understanding of gravity, and gravity is so admittedly poorly understood, how confident are we that dark matter is "a thing"? I know an intuitive sensibility is not the best foundation for an understanding of The Universe, but every time I read about dark matter, I get a very "Aether"-ish vibe. I just imagine comments section in the 2070 version of HN getting a good natured laugh about dark matter.

genug 11y ago
Systems like the bullet cluster (https://en.wikipedia.org/wiki/Bullet_Cluster https://en.wikipedia.org/wiki/Bullet_Cluster) are taken as evidence that most of the matter in large-scale, gravitationally bound astrophysical systems does not behave like luminous matter.
ISL 11y ago
Both dark matter and dark energy are descriptive placeholders for phenomena we partially understand. With them, we can simultaneously explain lots of observed effects. But, as in the time of the aether, we know we don't have the whole story.
chunky1994 11y ago
> gravity is so admittedly poorly understood Gravity as a force/phenomena in space on its own is actually very well understood. In fact it's possibly one of the most well understood theories we have in physics because of general relativity. However, at a particle scale we lack the understanding of how gravity would work. Dark matter is the collective name for whatever "stuff" exists in the universe that we predict it should have, however because it is noninteractive in any way other than exerting a gravitational pull (it accounts for a lot of astrophysical observations that otherwise are bewildering given what we see in the universe). We know it should exist, we don't know what it is and can barely understand its current properties. So indeed, it is quite possible that it might be Aether-ish if we end up finding something else that explains our current observations or a drastic overhaul of how gravity works at large scales (the latter being very unlikely because of how well GR has stood up to experimentation so far).

genug 11y ago

Systems like the bullet cluster (https://en.wikipedia.org/wiki/Bullet_Cluster https://en.wikipedia.org/wiki/Bullet_Cluster) are taken as evidence that most of the matter in large-scale, gravitationally bound astrophysical systems does not behave like luminous matter.

ISL 11y ago

Both dark matter and dark energy are descriptive placeholders for phenomena we partially understand. With them, we can simultaneously explain lots of observed effects. But, as in the time of the aether, we know we don't have the whole story.

chunky1994 11y ago

> gravity is so admittedly poorly understood Gravity as a force/phenomena in space on its own is actually very well understood. In fact it's possibly one of the most well understood theories we have in physics because of general relativity. However, at a particle scale we lack the understanding of how gravity would work. Dark matter is the collective name for whatever "stuff" exists in the universe that we predict it should have, however because it is noninteractive in any way other than exerting a gravitational pull (it accounts for a lot of astrophysical observations that otherwise are bewildering given what we see in the universe). We know it should exist, we don't know what it is and can barely understand its current properties. So indeed, it is quite possible that it might be Aether-ish if we end up finding something else that explains our current observations or a drastic overhaul of how gravity works at large scales (the latter being very unlikely because of how well GR has stood up to experimentation so far).