dark matter is just space

[doctor-bond]

Brilliant forum. As an inquisitive naif, it struck me that the puzzle of the ~ 85% (yep, wikipedia) missing matter in the universe might easily be solved if we conceived of space itself as having some substance. (I think in previous centuries it may have been called 'the ether'?)

 

Why bother with dark matter if space is stuff too?

 

 

I'd love to know why this is wrong.

 

 

 

 

 

[EdEarl]

The exact nature of dark matter is unknown. The ether has been discounted as incorrect. I believe many physicists think there are dark matter particles, but none have been discovered yet. We need to wait until more is known about dark matter.

[md65536]

Dark matter isn't distributed evenly through space. For example, gravitational lensing can show where matter is vs where visible matter is:

http://en.wikipedia.org/wiki/Bullet_Cluster#Significance_to_dark_matter

Two galaxies collide; normal matter interacts and slows more than non-interacting dark matter which passes right through.

 

Isn't dark energy evenly distributed through space ("vacuum energy")? It has a repulsive effect, and can't meaningfully be called "stuff" or matter.

[Bignose]

but as near as we can tell, space alone doesn't have the necessary attributes. That is, space itself doesn't seem to exert and experience the gravitational forces needed to prevent galaxies from flying apart. And, because we don't see galaxies flying apart and we don't see enough visible (or light) matter in those galaxies for all the gravity that ought to be there, we figure there is something we're not seeing keeping the galaxies together.

 

As alluded to above, we can actually make maps of where dark matter is most likely to be. http://www.scientificamerican.com/article.cfm?id=biggest-map-yet-of-universes

 

Dark matter isn't just space because space doesn't have higher and lower densities like that map.

 

But, it certainly has a significant number of unanswered questions at the moment.

[Dekan]

What about nebulae, such as M.42 in Orion. This is a huge cloud of gas with very hot stars embedded in it. The stars make the cloud glow like a cosmic aurora. You can see it in the night sky now that we're in winter. In the middle of the sword of Orion, a fine sight in 7 X 50 binoculars! Yet within bright M.42 is something startlingly different, the famous "Horsehead Nebula".

 

This looks like a black knight in chess. It doesn't glow - it's dark. The darkness is attributed by conventional theory to a mere contrast effect. But is that plausible? Couldn't the Horsehead be a local agglomeration of dark matter?

 

Also, sunspots are supposed to be dark only by contrast with the bright solar photosphere. But they might be nodules of real dark matter.

 

The point is this - suppose DM exists, and constitutes the majority of matter in the cosmos Then it must be everywhere, including on Earth. So shouldn't we see it all around us?

Edited November 16, 2013 by Dekan

[EdEarl]

The idea behind "dark matter" is that it cannot be seen, not that it can be seen as black or darker than elsewhere. Nebulas are made of cold regular matter. Since cold matter does not glow from heat, it is black or darker than surrounding stars. However, cold matter, such as ice can be seen. Dark matter is completely invisible, and does not interact with light except that dark matter has mass and gravity; thus, dark matter bends space-time and causes gravitational lensing.

Edited November 16, 2013 by EdEarl

[Dekan]

Thanks EdEarl, you say Dark Matter is completely invisible.

Don't you remember the Emperor's New Clothes as a past example of such ideas.

[EdEarl]

The Emperor's new clothes did not have mass (weight). Dark matter does; thus, it exists. One cannot see an atom, a quark, an electron or a neutrino, but they exist. Although, matter or light have an effect on atoms, quarks, electrons and neutrinos; only gravity affects dark matter as far as is currently known. Experiments at CERN may create dark matter and give us a better understanding of it.

Edited November 16, 2013 by EdEarl

[Bill Angel]

I would like to inject a speculative idea. There is a form of matter that would only interact with visible matter gravitationally, i.e. only through the exchange of gravitons. This would be matter that existed IN ANOTHER UNIVERSE. The idea that matter in our universe could be interacting with matter in another universe is an idea taken seriously by string theorists. For example, the idea is discussed in the book "The Hidden Reality, Parallel Universes and the Deep Laws of the Cosmos" by Brian Greene.

[Ringer]

Thanks EdEarl, you say Dark Matter is completely invisible.

Don't you remember the Emperor's New Clothes as a past example of such ideas.

But the reason it's invisible is the exact same reason its lensing effects can be seen when galaxies collide. It doesn't interact electromagnetically, it not being visible is just a extension of that attribute. Just because it can't be seen doesn't mean it can't be detected.

[DimaMazin]

Simply you should use exacter equation of force

For example

 

F=Gm1m2/r²+Gm1m2/10²⁰r

 

10²⁰meters - distance of change

Edited November 17, 2013 by DimaMazin

[Mr Monkeybat]

I have read that decreasing the attenuation of gravity slightly from the usual inverse square law provides a good description of the observed galactic rotations. So I have wondered myself whether Dark Matter could be explained by the mass of virtual particles in the quantum foam which would presumably be denser inside the galactic gravity well.

[Bill Angel]

I would like to inject a speculative idea. There is a form of matter that would only interact with visible matter gravitationally, i.e. only through the exchange of gravitons. This would be matter that existed IN ANOTHER UNIVERSE. The idea that matter in our universe could be interacting with matter in another universe is an idea taken seriously by string theorists. For example, the idea is discussed in the book "The Hidden Reality, Parallel Universes and the Deep Laws of the Cosmos" by Brian Greene.

There is also a tie in between what I suggested (above) and the so called Ekpyrotic Universe, which is based on the idea that our hot big bang universe was created from the collision of two three-dimensianal worlds moving along a hidden, extra dimension. See http://wwwphy.princeton.edu/~steinh/npr/

[swansont]

!

Moderator Note

The thread is not an invitation to discuss other alternate hypotheses. Please stick to explaining why the OP is wrong.

[DimaMazin]

but as near as we can tell, space alone doesn't have the necessary attributes. That is, space itself doesn't seem to exert and experience the gravitational forces needed to prevent galaxies from flying apart. And, because we don't see galaxies flying apart and we don't see enough visible (or light) matter in those galaxies for all the gravity that ought to be there, we figure there is something we're not seeing keeping the galaxies together.

 

As alluded to above, we can actually make maps of where dark matter is most likely to be. http://www.scientificamerican.com/article.cfm?id=biggest-map-yet-of-universes

 

Dark matter isn't just space because space doesn't have higher and lower densities like that map.

 

But, it certainly has a significant number of unanswered questions at the moment.

Doctor-bond didn't explain property of space of the OP. But space theoretically may work as gravitational mass, only when gravitational fields of masses cause this work.Then the space creates additional gravitation .

[Ringer]

Doctor-bond didn't explain property of space of the OP. But space theoretically may work as gravitational mass, only when gravitational fields of masses cause this work.Then the space creates additional gravitation .

So instead of a simple assumption (that there is matter that does not interact electromagnetically) you are making assumptions of space working in a way that is far from norm, and uses an unknown mechanism? We already know there are types of particles that can interact selectively with forces (photons interact electromagnetically but not gravitationally IIRC), so the assumption that there is a type of matter that won't interact electromagnetically isn't reaching very far.

[DimaMazin]

So instead of a simple assumption (that there is matter that does not interact electromagnetically) you are making assumptions of space working in a way that is far from norm, and uses an unknown mechanism? We already know there are types of particles that can interact selectively with forces (photons interact electromagnetically but not gravitationally IIRC), so the assumption that there is a type of matter that won't interact electromagnetically isn't reaching very far.

Usually a particle has some quantity of energy. And the any energy usually lets the particle be free from gravitational masses when the particle is free from electromagnetic force. Why "dark particles" aren't free from galactic congestions?