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@astro123 There’s a tautology in your critique. You’re attempting to suggest that there is evidence for dark matter. There isn’t. Dark matter is a theory, one that has not yet produced empirical evidence to support it (& perhaps cannot ever do so.)
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Biggest takeaway from this is how many underlying presuppositions appear to be assumptions.
>It's perhaps worth stopping to ask why astrophysicists hypothesize dark matter to be everywhere in the universe? >To explain observations of galaxies inconsistent with general relativity, the existence of dark matter was posited as an unknown and invisible form of matter calculated to make up more than a quarter of all mass-energy content in the universe Food for thought: the best current evidence of dark matter is…
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When it comes to cosmology, our observations have been using light, because that's what has traveled in space. It is pretty obviously not that useful to ask a dog to sniff the sky or a homing pidgeon to navigate to Alpha Centauri, or something. We've obviously long since passed using only the visible spectrum. We also recently added gravitational wave detection to our repertoire. I seriously doubt any animals out the…
Yes and no. Yes, we're seeing gravity waves and radio waves and gamma rays and near infrared and millimeter wave and neutrinos, and maybe a few others that I forget. We're way past human senses, or any animals. And yet I keep thinking of a deaf species that runs across Beethoven's Ninth Symphony. They can put an oscilloscope on the pressure waves in the air, so they can "see" what's going on. They can study the diffe…
(Heck, you don't even need a deaf species. There's a lot of reason to believe that birds don't experience music the way we do, and they're not even strictly speaking "aliens".)
So there's no particular gain to worrying about being limited to "human" senses, because there is no actionable way to "transcend" them in that sense other than by being something other than what you are. It's certain to be true, there's nothing to be done about it that we aren't already doing, and thus, it isn't really an interesting criticism to vaguely suggest that we should somehow be something other than ourselves.
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The fact that SOME galaxies are inconsistent with the theory of Dark Matter actually strengthens that theory. If the difference in rotation curves, the usual signature of dark matter at the galaxy level, from what GR predicts based on the mass of luminous objects was due to a modification in the way gravity works, then that should apply to ALL galaxies. Modified Newtowian Dynamics (MOND) (or the relativistic TeVeS mo…
To be clear, they're not inconsistent with the theory of dark matter, they're inconsistent with those galaxies specifically having dark matter. The author was wording that in a confusing way.
I wish the article had made that apparent.
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To be clear, they're not inconsistent with the theory of dark matter, they're inconsistent with those galaxies specifically having dark matter. The author was wording that in a confusing way.
To be even more clear, "dark matter" isn't a theory. It is a name for something we need theories about. I wish the article had made that apparent.
@astro123 Sorry my comment uploaded before I was done. It is an error to state that there is evidence for dark matter. There is no evidence for it other than that as a hypothesis it adds support to a larger cosmological theory; that of the so-called Big Bang. But that is basically a circle in the proof. A tautology.
What about the Bullet Cluster?
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When it comes to cosmology, our observations have been using light, because that's what has traveled in space. It is pretty obviously not that useful to ask a dog to sniff the sky or a homing pidgeon to navigate to Alpha Centauri, or something. We've obviously long since passed using only the visible spectrum. We also recently added gravitational wave detection to our repertoire. I seriously doubt any animals out the…
About this: " It is pretty obviously not that useful to ask a dog to sniff the sky or a homing pidgeon to navigate to Alpha Centauri, or something. " That example might be bad, but there are others that are valid. For instance, in healthy human women, the menstruation cycle seems to be the exact length of the moon's orbit. Is that a coincidence, or do human bodies have a way of gaining data from the moon? If so, what…
I know that my cats notice. Indeed corals worldwide notice, despite lacking eyes.
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About this: " It is pretty obviously not that useful to ask a dog to sniff the sky or a homing pidgeon to navigate to Alpha Centauri, or something. " That example might be bad, but there are others that are valid. For instance, in healthy human women, the menstruation cycle seems to be the exact length of the moon's orbit. Is that a coincidence, or do human bodies have a way of gaining data from the moon? If so, what…
> For instance, in healthy human women, the menstruation cycle seems to be the exact length of the moon's orbit. That seems to be absolute coincidence. If there was a value in syncing to the lunar cycle it would stand to reason there would be a synchronization with the characteristics of the lunar cycle - ie ovulation on the 14th day or something. As it is, there is no link between when a woman's cycle and the lunar…
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To be even more clear, "dark matter" isn't a theory. It is a name for something we need theories about. I wish the article had made that apparent.
Sorry but that’s an intellectual dodge. A verbal fiddle. Saying it is a “name for something” doesn’t make the fact that it’s a hypothesis disappear. One is simply positing the need for more “Russian dolls” inside the Russian doll one has hypothesised to begin with.