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Mild mannered
2009-Feb-11, 09:37 AM
Hi,
Just a query - not a theory - I'm no boffin, just interested.
I was wondering about Dark matter - could it be a form of pure Gravity?
I was thinking of a very massive object - say a Galaxy! charging through space churning up Space/time and spinning bits of it into swirling vortexes like eddies in a river.

I know planets drag Spacetime as they spin.

I also thought of a blackhole spinning and doing crazy stuff to Spacetime but simultaneously in motion as the Universe expands - what would the effect on Gravity that it leaves in it's wake be like?

As stated not a theory just an innocent question to ponder.
Cheers
Mild

Krowser
2009-Feb-11, 02:51 PM
Now thats just silly.

Everyone knows that dark matter is excreted by Niblonians and makes for excellent starship fuel. (Futurama, anyone? :P)

Cougar
2009-Feb-11, 04:00 PM
...Dark Matter... swirling vortexes like eddies in a river...?

Before giving this much thought about why it wouldn't work, I kinda like the idea....

Oops - reality just crashed the party. The observed effect of dark matter is at least 5 times greater than the effect of regular, baryonic matter. It doesn't make sense that such a "spin-off" could be larger than the thing it spun off of.

Mild mannered
2009-Feb-12, 10:05 AM
Thanks for the reply
I can tell there's no point continuing this - I just wondered is all.
But what does happen to spacetime as very massive objects pass through? Does it just snap back and smooth out or is there a residual warpage?
If this is also plain silly then sorry - but I'm never afraid to ask.

Before giving this much thought about why it wouldn't work, I kinda like the idea....

Oops - reality just crashed the party. The observed effect of dark matter is at least 5 times greater than the effect of regular, baryonic matter. It doesn't make sense that such a "spin-off" could be larger than the thing it spun off of.

mugaliens
2009-Feb-14, 09:33 PM
Hey, no - I like this. When you mentioned eddies, I immediately pictured my younger days swimming in a turbulent river, where clamber on top of a rock to regain my breath and watch the eddies created by the current continue in mini-whirlpools which lingered downstream for many times the distance as the diameter of the rock which created them.

Gravitational eddies? Hmmm...

Cougar, your rationalization is spoiling all the fun! I wonder if it's necessary, though... How long would gravitational eddies last? They wouldn't necessarily die out as water eddies do from the friction with the surrounding water. Frame-dragging "friction?" Sure. But to what effect? And if baryonic matter approaches one of these eddies, what happens? It's not a mass, per se', so I would imagine the effect would be to move the mass one way as the leading edge of the eddy swirls one way, then the other as the eddy swirls the other way.

The net change on the velocity vector would be zero. Still, there would be some serious sheer forces as the baryonic matter passed through the eddy.

Ok, Cougar - now you can tear down the sandcastles.

slang
2009-Feb-14, 10:46 PM
Gravitational eddies? Hmmm...

'Eddies,' said Ford, 'in the space-time continuum.'
'Ah,' nodded Arthur, 'is he? Is he?'

(src (http://www.saunalahti.fi/~huuhilo/dna3.html))

Mild mannered
2009-Feb-18, 12:07 PM
Thanks again to all who took time to reply - I know most were tongue in cheek but I just wondered - mugaliens, joking aside what do you think Spacetime does after a massive spinning body passes at high speed? Does it leave a residual wake or possible eddy?

Hey, no - I like this. When you mentioned eddies, I immediately pictured my younger days swimming in a turbulent river, where clamber on top of a rock to regain my breath and watch the eddies created by the current continue in mini-whirlpools which lingered downstream for many times the distance as the diameter of the rock which created them.

Gravitational eddies? Hmmm...

Cougar, your rationalization is spoiling all the fun! I wonder if it's necessary, though... How long would gravitational eddies last? They wouldn't necessarily die out as water eddies do from the friction with the surrounding water. Frame-dragging "friction?" Sure. But to what effect? And if baryonic matter approaches one of these eddies, what happens? It's not a mass, per se', so I would imagine the effect would be to move the mass one way as the leading edge of the eddy swirls one way, then the other as the eddy swirls the other way.

The net change on the velocity vector would be zero. Still, there would be some serious sheer forces as the baryonic matter passed through the eddy.

Ok, Cougar - now you can tear down the sandcastles.

mugaliens
2009-Feb-18, 09:44 PM
Thanks again to all who took time to reply - I know most were tongue in cheek but I just wondered - mugaliens, joking aside what do you think Spacetime does after a massive spinning body passes at high speed? Does it leave a residual wake or possible eddy?

If you've ever done any baking, using a hand mixer, try mixing some batter with just one beater instead of two. As you drag the beater sideways through the batter, you see as each unit of batter gets progressively closer to the beater, the beater beats the batter better, besting the batter beautifically...

[jar-jar wwwbbbwpbwbppbpwwW!!)

...as you drag the beater sideways through the batter, you see the batter swirling around the beater much as space-time would swirl around a rapidly spinning, rapidly moving black hole.

But no, no eddies.

Frankly, I thought my "Eddies" concept was rather neat, but know of no possible mechanism by which it might actually exist given real-world physics.

Perhaps Ed or Ed knows... :)

trinitree88
2009-Feb-18, 09:54 PM
If you've ever done any baking, using a hand mixer, try mixing some batter with just one beater instead of two. As you drag the beater sideways through the batter, you see as each unit of batter gets progressively closer to the beater, the beater beats the batter better, besting the batter beautifically...

[jar-jar wwwbbbwpbwbppbpwwW!!)

...as you drag the beater sideways through the batter, you see the batter swirling around the beater much as space-time would swirl around a rapidly spinning, rapidly moving black hole.

But no, no eddies.

Frankly, I thought my "Eddies" concept was rather neat, but know of no possible mechanism by which it might actually exist given real-world physics.

Perhaps Ed or Ed knows... :)

Mugs...'Just believe everything I tell you, and it will all be very, very simple.'
'Ah, well I'm not sure I believe that.'
stole one of your lines...fortunately there are enough skeptical minds out there, but it's still surprising what a lot of people buy into..:shifty:.pete