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Mild mannered
2007-Jul-02, 09:55 AM
If you stretch an elastic band you get get potential energy - IE potentially if I let go one end it can smack you in the butt with the other.

Energy and Mass are equivalent - so I wonder is the Universe (Space-Time) being stretched by it's own expansion and building up various Energies - such as potential, Kinetic, Enertia - and could these be what we perceive as Dark Matter?

Warping of Space-Time anyway it occurs gives us Gravitional effects - no?

antoniseb
2007-Jul-02, 11:01 AM
I imagine you are talking about Dark Energy here, not Dark Matter.

Mild mannered
2007-Jul-02, 12:20 PM
Sure - of course you are correct
But since matter and energy are interchangeable..?
(By the way - hi Antoniseb - it's been a while)

Cougar
2007-Jul-02, 02:10 PM
Energy and Mass are equivalent - so I wonder is the Universe (Space-Time) being stretched by it's own expansion and building up various Energies - such as potential, Kinetic, Enertia - and could these be what we perceive as Dark Matter?

Warping of Space-Time anyway it occurs gives us Gravitional effects - no?

The universe IS being stretched by its own expansion, but spacetime in the universe is not a rubber band - the expansion is not building up any comparable tension. The pervasive vacuum energy that is effecting (yes, effecting) the expansion has, as you say, a mass equivalent that is largely responsible for "flattening" the geometry of spacetime in the universe. Dark matter, on the other hand, congregates around galaxies and clusters.

Sp1ke
2007-Jul-02, 02:41 PM
And although energy and matter are interchangeable, Dark Energy and Dark Matter aren't.

Mild mannered
2007-Jul-03, 08:48 AM
Thanks for the answers - this all fascinates me even if I have a hard time getting my head around it!

Cougar: "Dark matter, on the other hand, congregates around galaxies and clusters"

Do we know this for a fact or is this just where we see the effect (affect?) - could there be clumps in the interstellar gulfs that are hanging around but with no gravitaional frame of reference remaining invisible?

Cougar
2007-Jul-03, 01:59 PM
And although energy and matter are interchangeable, Dark Energy and Dark Matter aren't.
Ha! Good point.

Cougar
2007-Jul-03, 02:06 PM
Cougar: "Dark matter, on the other hand, congregates around galaxies and clusters"

Do we know this for a fact or is this just where we see the effect (affect?) - could there be clumps in the interstellar gulfs that are hanging around but with no gravitaional frame of reference remaining invisible?
Good question. I don't know it for a fact because I have no evidence handy, but I kind of expect researchers in the field do, probably from observations of weak gravitational lensing. Theoretically, dark matter does interact gravitationally, so in general it should follow the luminous mass.

Michael Noonan
2007-Jul-03, 02:54 PM
Thanks for the answers - this all fascinates me even if I have a hard time getting my head around it!

Cougar: "Dark matter, on the other hand, congregates around galaxies and clusters"

Do we know this for a fact or is this just where we see the effect (affect?) - could there be clumps in the interstellar gulfs that are hanging around but with no gravitational frame of reference remaining invisible?

There are many ideas being floated and with each new discovery a chance the really big picture may be known.

One of the interesting ideas in this forum was that we were in a massive black hole universe size and that the far edge was a long way into the future. This sort of idea would mean that matter and space and time are being stretched. The matter sort of clumps mostly where matter can be seen so that accounts for dark matter mostly, well sort of.

The stretch is then your elastic band which is dark energy. The slight problem the reader encounters is that the end or total transition in the way off future is visible long before it happens, curious stuff this dark energy.

No doubt about it we live in exciting and interesting times. This is a great forum with many people contributing ideas, there are answers just not fully known ones yet. Douglas Adams probably said it best on the cover of "The Hitchhiker's Guide to the Galaxy" ... DONT PANIC ... in big comforting red letters. :)

Mild mannered
2007-Jul-04, 08:26 AM
Thanks all
Varied and interesting comments
Yes, Cougar, I agree it is a great forum - aside from the amateurs like me with a hobby interest there are loads of top notch brains willing to pitch in and try and help answer questions
Good stuff!