Gravity - a repulsive force???

[Rev. Green]

What's wrong with this argument?
Twelve billion years ago the Universe was less dense than it had been thirteen billion years ago, but more dense than it would be eleven billion years ago.  So when we look at an object at a distance of twelve billion light years we see denser space beyond it, and less dense space this side of it. Consequently, we would expect gravity to pull the object away from us.  This implies that gravity causes the Universe to expand!

[rojash]

Is this a joke?
When something expands it becomes less dense. The universe has expanded, therefore it is less dense - everywhere. There aren't denser bits further out.

[Zacs-Master]

v = Hod

[jake-the-peg]

Because you have massive bodies on all sides of you and gravity pulls in all directions your force from one direction is counteracted by opposite ones of (roughly) equal mass.

But I think you might be missing what is meant by an "expanding universe" it's not the stars that are being flung away from a giant explosion.

Space itself is expanding taking every thing with it like currents in a loaf of bread rising.

We know this because the further away the object is the faster it is receding you only get this if there's a constant rate of expansion between the objects

[d9f1c7]

I'd stick to religion rev if I was you.

[scowie]

We dont actually see a greater density of matter as we look further away, but supposing there was a greater density in the past (as the big bang theory suggests), since this greater density would be at an earlier time it would not be acting on us or any other galaxy at present. At any one time the density in each direction is always the same.

[cupid04]

Rev Green in the observatory with the telescope!

[scowie]

...From a galaxy twelve billion light years away, the density of their galactic neighbourhood would look pretty much the same as ours does.

Btw, imo, the universe is not actually expanding at all, and the idea that it does comes from misinterpreting galactic redshifts as a doppler effect (implying galaxies are generally flying away from each other) when they are actually a scattering effect. Light simply loses energy through it's interaction with matter in the intergalactic medium. This documentary may enlighten you... http://bit.ly/sv3MGo

[Jonathan-Joe]

Over the centuries, scientists have come to accept the idea that the earth does not occupy a special place in the universe and that the universe looks pretty much the same, from all viewpoints and directions of view.
By placing the earth in a special region of the universe, that is the region of lowest density, you challenge this idea. To support it, you must explain how we came to occupy this privileged place (unless you expect science to accept it as just co-incidence).

[Rev. Green]

If I throw a rock due South, it will land slightly to the West: I'll calculate the wrong landing site unless I include Coriolis force or, equivalently, allow for the rotation of the Earth. 
Distant objects are observed to have denser space beyond them. (Space around them looks uniform to them, but not to us.)
My question is: if I compute the gravitational force on a distant object caused by the APPARENT imbalance of objects around it, does the calculation show it to retreat at the correct speed, or do I still need a term for dark energy, just as I needed a Coriolis term in the first example. 
Distant objects which appear densely packed will be sparser now, if we could have a universal 'now', but that is irrelevant. I'm asking if the calculations give correct answers if we use observations, and the Universe unquestionably appears denser further away, having less space between objects. 

[Rev. Green]

Jonathan-Joe: The Earth APPEARS to be in the lowest density position of the Universe because we see it now (almost). Other objects APPEAR to us to be in denser regions because we see them as they were some time ago. 
Obviously, all other observers would think they were in a sparse region, and the Earth would appear to them to be in a denser region. 

[mibn2cweus]

It makes sense to me that whatever force is driving the expansion is less impeded as a result of diminished mutual gravitational attraction between objects as they move further away from one another. Could this explain the apparent acceleration in the rate of expansion? This leaves in question what the force is that is driving the expansion.

[jake-the-peg]

You have to do the numbers

Gravity is a pretty weak force and I'm not sure that over the gargantuan distances that we're talking about it amounts to a whole hill of beans

The mass of our galaxy is about 10^42Kg small estimate for the size of the universe about 10^50 G 6.67300 × 10-11

So the force between two galaxies at that range is about 10^-25 N

That is so minute that any random variations in matter distribution will have a much greater effect

Trust me - the calculations going into the models trying to explain the Universe are pretty sophisticated and the chances of people slapping their foreheads and saying "Silly us the Universe is Newtonian after all we just forgot to account fot this" is remote

http://en.wikipedia.org/wiki/Lambda-CDM_model

Is the best model so far

[weecalf]

If sitting on the back of a coal lorry with my legs dangling over the tail end .The lorry is travelling at 40 mph .I have a football which I throw in the air .What is the highest I can throw it so it still land back in my hands not on the road Does gravity kick in here too.

[albaqwerty]

my head hurts......

[New Judge]

Did you try weecalf's idea, then,albaqwerty, and the ball came back and hit you on the bonce?

[Rev. Green]

Thanks Jake. I'd Mark yours as Best Answer if I hadn't already tried to mark your previous answer as Best Answer - and made a mess of it.

[Old_Geezer]

It depends on how long your arms are weecalf. You need to calculate how long the ball will be in the air and how far that represents at 40mph. Time taken will, of course, be inversely proportional to the gravitational force. Then you can check if your arms are long enough to reach the ball. I suggest tying yourself onto the lorry because falling out when you stretch for the ball isn't recommended.

[skep]

Not sure where you get the information for your question.

Additionally, we are still trying to understand gravity and much effort is being expended in this regard.

Scientists are still trying to figure out how to add gravity to the original three basic forces in classical physics.

Usually gravity is merely included to make the four basic forces since its addition will eventually be explained.

I'm not saying that you have a proprietary interest in refuting evolution but if you do, it will not be possible to use real science to do this.