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Dark matter is so-named because scientists can't see it or detect it - so what's the evidence that it actually exists?
I wonder why the possibility that one of our tenants might not apply equally at large distances never occurs to us? For instance, If F = ma was only valid locally that would explain all of your proofs.
In other words, could the presence of matter in space attenuate the gravitational effect? I'm sure there must be some analogies for this, but I just can't think of any right now!
So gravity provides negative feedback for gravity.
We can always say, "Hey, maybe physics in far away places is just crazy!" But this is just to give up. And it's not really that likely an answer, since assuming that physics in far away places isn't crazy actually gives us good results.
For example, it is commonly accepted that gravity is the result of matter distorting spacetime. We observe gravitational effects in our "near space" where there is, relatively speaking, a lot of matter, and, therefore, our "near space" is considerably distorted. Are we sure that gravitational effects are the same in volumes of space that contain relatively little matter and are, therefore much less distorted?In otherwords, could the presence of matter in space attenuate the gravitational effect? I'm sure there must be some analogies for this, but I just can't think of any right now!
Do you mean that, for example, gravity constant G is stronger if the density of matter is lower? Then we could invoke void polarization and negative energy: a great density of matter would generate greater negative energy and so lower gravitational interaction. Dark matter and dark energy explained together!
The Pioneer anomaly is the perfect example of something being slightly wrong with F = ma.
So all the evidence would indicate that the standard model is at best 10% correct as we are unable to account for 90% of the universe using current mass attraction theory.
But what if there is a magnetic binding force which turned out to be nine times stronger than gravity? Google magnoflux for an alternative electro-magnetic view of the universe.
If you mean the standard model of cosmology, then the evidence is that the standard model is incredibly well supported, as this model takes into account dark matter.
Both the standard models have been conceived assuming that electricity in space can be neglected. This could be accepted before the solar wind was identified but not now. In fact voyager has just reported flying through a magnetic fluff cloud that should not be there; far out in the solar system. But magnetism is there??? and it has an effect!!RegardsCliveS
But what if there is a magnetic binding force which turned out to be nine times stronger than gravity?
I totally agree, but what I was getting at was the so called 90% may not actually be 90% exotic matter. Brown dwarfs are quite unique in that they don't have to be formed on the disc, for example in the halo most of the stars are part of globular clusters low mass and old but some could be failed stars. As you rightly say we are still in the process of mapping our own galaxy let alone others but just as we have made ball park figures for the number of galaxies in the universe and distribution of certain stars, distribution calculations have also been made for brown dwarf which of course is far below 90%. Although they still indicate towards there being a lot and this would definitely affect the overall figure of 90% exotic matter and therefore should (and already is) considered when mapping dark matter distribution in the universe.
Hmm I am not so sure I agree that having say a 80% -20% or 70%-30% distribution would effect the deviations so much that they would not be observable. Dark matter is still unknown and the sloan and wmap rely on detecting the effects of gravity from dark matter, in fact all matter has a relationship with gravity.
1. Rotation curves of galaxies: We can look at how fast a galaxy is rotating and use that to calculate how much matter is in the galaxy (and roughly its distribution). We can also look at how much light is coming from the galaxy and use that to tell how much matter is there (and roughly its distribution). These two do not match up.