Big Bang and Alternatives

Hmm yeah, but if the range of gravity wasn't limited, then could the low limit have a significant effect?

Yes. For galaxies to be able to orbit each other the minimum speed for the propagation of gravitational force would have to be large enough for that force to travel between them in a time period that is very very short compared the orbital period.

20 trillion times c ?

LB

Well, I picked some numbers, I hope they are realistic.

Assuming the range of gravity is unlimited:
Two galaxies with combined mass 2*10^40 kg
Distance 400,000 Ly (about 4*10^21 m)

Orbital speed is app. 10^4 m/s
Orbital period in the order of 10^18 s (that's ehrr 3*10^10 year, hehe)

For gravity to travel 400,000 Ly at 2*10^10 c takes 2*10^-5 year or 630 seconds.
My guess is you'ld need some patience if you want to watch these galaxies spiral away from each other.

I don't know about you, but I don't think gravity is as far reaching as is said. Now, I may just be dumb here, so just bear with me. In my opinion(be it right or wrong) is that gravity is not the cause, but the effect. Due to mass bending space and time, gravity is created. If there is no mass in a general area, there is no gravity. This applies to several parts of the universe, so I would think, because if every part of space had mass, then it would be one huge heap of mass and the gravity would be so intense we would be crushed. I believe that electro-magnetism has a far greater say and command as to what is happening in the universe than gravity. In my opinion electro-magnetism is the cause of placement of everything, and gravity is merely an after-thought. Therefore if you were to look at the movement and positions of the galiaxies and how it is reacting with everything else, you would need to look at electromagnetism. They have been able to re-create in labratories "spiral galaxy-like" creations by shooting electromagnetism through plasma. It is very interesting indeed. These are just my thoughts... what do you think?

US AIR FORCE - Korean Linguist for life

What do I think?

Cindy raised the question why galaxies don't just clot together. Larry pointed out that the range of gravity may be limited. Then I brought a possible finite propagation speed of gravity. Which doesn't seem to have a lot of impact unless m/r is very high, IOW if very heavy masses are in a very tight orbit.

Personally I like the idea of a limited gravity range and this is why: When we look out of our hubble window, we see galaxies,galaxies and more galaxies. On a rare occasion we see two galaxies collide (falling through eachother). We might as well build a model that allows for all those galaxies.

Dutch bum.

[Michiel] "Well, I picked some numbers, I hope they are realistic."

400,000 LY is not much more than the diameter of an average galaxy. I would be inclined to characterize two galaxies with a center to center distance of 400,000 LY as being in collision, or perhaps a very near miss, rather than as orbiting. Some individual stars from each will be close enough for direct gravitational interaction.

Try 4 million LY. Or 40.

LB