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Errata: * purported dark matter * purported dark energy * purported black holes * purported big bang

codethief 8y ago
I wouldn't put dark energy, black holes and the big bang on a level with dark matter. Dark energy is just a name for what's otherwise known as cosmological constant. Yes, some people might believe that it's unnatural for the cosmological constant to be as small as it is and others might believe that it should really follow from a proper quantum theory, so there are definitely a bunch of open questions. But that doesn't change the fact that it's there. The same thing goes for the Big Bang and black holes. We have absolutely no reason to believe they don't exist. (To the contrary, we have every reason to believe so.) Dark matter, however, is just one possible (and comparatively speculative) explanation for various experimental deviations from theoretical predictions, regarding among others the stellar velocity distribution within galaxies, gravitational lensing and structure formation.
cambalache 8y ago
* purported atoms * purported molecules * purported cells * purported persons
rstuart4133 8y ago
Yes, you are right, dark matter,and the big bang are just the leading theories explaining an observed feature of our universe: - What is holding the galaxies together, given they are rotating faster than gravity from observable matter can cope with? - Why is the Universe so uniform, given parts of it we can see are outside of each others light cones? I read the OP as using the names of these theories as a handle for the effects they account for, which is fairly standard practice. Even physicists investigating other explanations do this. I'm not sure dark energy or black holes fit that description. "Dark energy" is a reference to something that is causing distance objects to accelerate away from us faster than near objects. Obviously that takes energy. Dark energy is just a place holder name for that energy given we don't have a clue what it is or where it comes from. A black hole is a name for enormously heavy, small (smaller than the schwartz radius) and very dark objects whose existence is inferred from the their gravitational effects. They are found at the centre of galaxies, among other places.

I wouldn't put dark energy, black holes and the big bang on a level with dark matter. Dark energy is just a name for what's otherwise known as cosmological constant. Yes, some people might believe that it's unnatural for the cosmological constant to be as small as it is and others might believe that it should really follow from a proper quantum theory, so there are definitely a bunch of open questions. But that doesn't change the fact that it's there. The same thing goes for the Big Bang and black holes. We have absolutely no reason to believe they don't exist. (To the contrary, we have every reason to believe so.) Dark matter, however, is just one possible (and comparatively speculative) explanation for various experimental deviations from theoretical predictions, regarding among others the stellar velocity distribution within galaxies, gravitational lensing and structure formation.

cambalache 8y ago

* purported atoms * purported molecules * purported cells * purported persons

rstuart4133 8y ago

Yes, you are right, dark matter,and the big bang are just the leading theories explaining an observed feature of our universe: - What is holding the galaxies together, given they are rotating faster than gravity from observable matter can cope with? - Why is the Universe so uniform, given parts of it we can see are outside of each others light cones? I read the OP as using the names of these theories as a handle for the effects they account for, which is fairly standard practice. Even physicists investigating other explanations do this. I'm not sure dark energy or black holes fit that description. "Dark energy" is a reference to something that is causing distance objects to accelerate away from us faster than near objects. Obviously that takes energy. Dark energy is just a place holder name for that energy given we don't have a clue what it is or where it comes from. A black hole is a name for enormously heavy, small (smaller than the schwartz radius) and very dark objects whose existence is inferred from the their gravitational effects. They are found at the centre of galaxies, among other places.