Note: I'll admit as my first line that i am extremely ignorant of these subjects(on a math level), so i'm not trying to make a theory, or even a hypothesis here. Just want something explained.


As far as i understand Black Matter is, for now, an artifact we use because galaxy rotation doesn't work without more matter around the galaxy. That is, not in the center. Some Black Matter have been found, but the majority of the matter needed is still not verified.

So, studying some M-Theory(just for haha's) i got an idea. It is most likely wrong(on par with the, go out one side of the universe and come in the other, ideas you get as a 12 year old). But still.

The graviton would be a looped string, not fixed on our brane(in contrast to the other forces). Which means gravity can leave our brane, and influence other branes. So if M-Theory is actually reality, and not just a phillosophy(have there been made a test or observation that updates it to theory yet?), could it be that matter in other branes next to us, could be (some of) the Black Matter we still haven't found.

If we have a lot of branes next to each other. And look through them(for a 2d image, place them on top of each other and look down through them) have a somewhat uniform attraction across the sum of the branes. So gravity in the center of the galaxies isn't that much more than at the edges of the galaxy.

Of course it could also end up as galaxies having about the same position in all the branes, simply because they are being attracted to each other.


As i stated, i don't know that much on the subject, and this idea is most likely completely wrong, and build on the fact that there is certain information on how M-Theory works that i don't comprehend(or have never been explained to me).

But i would very much like to know why this could NOT be the case.

Sincerely
Tobias.

As a matter of fact, Stephen Hawking discusses a related possibility in his book The Universe in a Nutshell. In my edition, it's on pages 182 - 188.

Please tell me if this is too much quote:

"In this brane world, we would live on one brane but there would be another 'shadow' brane nearby. Because light would be confined to the branes . . . we could not see the shadow world. But we would feel the gravitational influence of matter on the shadow brane"

He goes on to say that we would be forced to interpret this influence as dark matter because the only way to detect it is through gravity rather than light.

Hum,
Yeah that could be possible.

During symmetry breaking in the old classic bigbang theory there was a special lie group (E8 x E8) that broke into two parts very early on.

One went on to form our universe while the other could have formed a slightly different shadow universe.
However the problem is that there still isn’t enough shadow matter created to explain what we observe (we need about ten times the amount, more).

What? there can only be one(1) other brane? i thought the number could be infinite..

Or rather, now that i think of it, i didn't see any number, but i don't understand why there would only be two branes(ours and shadow).

Hum,
Indeed comrade,
there could be a infinite amount of branes.

But I was just point out the old idea that the universe is the collision of just two of those 5 dimensional branes.

I’m not aware of any proposals of a multi brane collision. (simplest is easiest).

Blob: I was not talking about collision(which would mostly make sence with just one other brane). I was talking about an infinite amount of branes, really close to us in a higher dimensional space, would cause an effect on our brane, which would amount to the Black Matter we can't account for.

Tobias: have you ever visted Steinhardt's page? Perhaps it might address some of the answers you seek.

It's commonly called "dark" matter, rather than "black". You have part of the explanation. Back in the 1930's, Fritz Zwicky discovered that the luminosity of a galaxy cluster was not as good a tracer of the mass as was previously thought (i.e., On the Masses of Nebulae and of Clusters of Nebulae, F. Zwicky, Astrophysical Journal 86: 217, Oct, 1937, though his first paper on dark matter was in 1933). But Zwicky, and other astronomers at the time, could only assume that the "missing" mass was comprised of ordinary objects, but just dark ones, like old used up stars, clouds of dust & gas, and such.

However, studies of the cosmic microwave background (CMB), and its spatial distribution on the sky, have revealed another kind of dark matter, non baryonic dark matter, a different kind that Zwicky was talking about. It's called non baryonic because it cannot interact with photons, and therefore cannot be composed of baryons (like protons, neutrons, electrons & etc.). This kind of dark matter, which cosmologists now think makes up most of the mass of the observable universe, is derived from the spatial anisotropies in the CMB. It is derived by measuring the relative heights of the peaks you see in the plot at the bottom of the linked page.

So, there are two different kinds of "dark matter", both of which we "see" through gravity, but in remarkably different ways.

This is a large part of of what M-theory & string theory in general say. Gravity is the only force which can extend beyond the boundaries of branes. Dark matter is a "classical" solution to the observational problem, because it is the simplest solution. After all, we already know that there is such as thing as non-baryonic dark matter (neutrinos, for instance). So, dark matter is in this sense, just an assumption that we have more of the same kind of stuff. But it may well be that there is no dark matter, and that we are really seeing the effect of a slightly different formula for gravity than we think (i.e., MOND), or perhaps gravity extending between branes, as from M-theory.