Spyman

Is the GRBs known enough to be sure that the "energetic ones" didn't have a head start ?

Yes, in the Cyclic model, Dark energy corresponds to a force between the branes. (Guessing Cyclic Universe is what you are asking about, but not sure.) Cyclic Universe: http://en.wikipedia.org/wiki/Cyclic_Universe Dark Energy: http://en.wikipedia.org/wiki/Dark_energy And here are some other links you might find worth reading: http://www.space.com/scienceastronomy/astronomy/bigbang_alternative_010413-1.html Ekpyrotic Universe: http://en.wikipedia.org/wiki/Ekpyrotic_universe Multiverse: http://en.wikipedia.org/wiki/Multiverse

For me a Vampire would be a magical and evil supernatural creature. They are undead and can't be killed.

We seems to agree, but Atheist is not convinced. The pebbles path would change even if the hole moves along with the same speed. (Try to put a pepple in the slope of a hole, both does move with the same speed.) Also the center of the hole moves with c, but the edge will move out with the speed of c. (Exept in the direction, since both move with c, the center is on the front edge.) If the light already are on the same line then they cant "bend" any closer but the beams should lose energy when in opposite direction.

PUH ! This discussion has rised to a level far to high for me. (I tried to follow the answer to woelen - got lost fast.) From my simple point of view there can only be three different outcomes of such an experiment: 1) The beams would bend independent of direction. (Always bends.) 2) The beams would bend dependent of direction. 3) The beams would never bend. (Independent of direction.) If light curves space-time I would think nr. 3 is ruled out. So what you are saying here is that nr. 2 might be correct but implies that you would give nr. 1 a higher propability ? (Or maybe you mean that they bend dependent of direction but if they are parallel there will be some cind of special condition ?)

Your experimental error is just far too large Well, if Mr.North decides to take some time off and goes to Sahara where he is "lazily drifting all over the place", and maybe even visits the pyramids, I would like to think that my compass would notice some difference or is a (nearly) 180 degrees turn to small ? Or was it just a weekend trip so he is back home in Arctic now ? LOL According to my compass the magnetic north is still in the direction it always has been and not drifting much at all. Did you not notice that I bolded the "funny" part ?

LOL According to my compass the magnetic north is still in the direction it always has been and not drifting much at all.

Even tough the Moon won't escape i think this is the thread J.C.MacSwell remembers: (It also covers the slowing rate of Earths spin.) moon is going away http://www.scienceforums.net/showthread.php?t=22011 The effect should be extremely tiny compared to the total tidal stress of Earth.

Just to verify if I understand that part correctly: Two parallel laser beams, in the same direction, will not gravitationally attract each other. (Rest mass for photons = zero.) But if they are in opposite directions and passing each other, then they will both bend. (Very slightly towards eatch other.)

Don't forget this:

Close enough, just not sure what would happen to space outside a universal sized black hole, if you actually could move all mass and energy together, (locally).

http://en.wikipedia.org/wiki/Gravity

From a human perspective it appears to be very much, but the Earth is HUGE. Cars, buildings and so forth is made from a tiny bit of the crust and the crust with all its mountains and oceans are still just a very small part of Earth. You may want to read this: http://en.wikipedia.org/wiki/Structure_of_the_Earth

awful = terribly I don't think that was what you meant because your post makes more sense with "awful" removed.

From my understanding a Big Crunch would be like the Big Bang but in reverse, any locally movement would not make any difference. There is no known escape path for a powerfull spaceship, it could take off in any 3D direction but still be caught in the crunch. If it would be similar to your local ball drop then the beings on the little blue ball should be able to measure in which direction they are moving and the speed caused by the expansion/collapse.

I think you missed a few! LOL ! BTW: I think You missed the point.

Well I did drop them and they are not crunching, maybe I dropped them in the wrong direction ?

Now I am confused... Why would a local movement of mass affect the global size or shape of the universe ?

Even if the water is moving it will still be under influence of gravity. When the piston is submerged it will be like a seesaw with the 100 kg piston on one side and 99 kg water in the plumbing on the other. The water in the cylinder and in the plumbing will have to accelerate at the same rate as the piston, otherwise a pressure that will counteract the descend will build up in the cylinder under the piston. The minimum weight on the parts to be accelerated is 199 kg, with larger plumbing more water is added and the weight raises. Now, if there was a race between to identical motorbikes, the first carrying a weight of 100 kg and the other 199 kg, which one would be able to accelerate fastest ? The only difference between the plumbing and the pool scenario would be friction inside the cylinder and the plumbing, if the friction is as low as in a pool, (which problably requires plumbing of the size of a pool), then the piston would descend with the same rate as if dropped in a pool.

I have two dogs and one cat, all three of them give me fleshwounds on a more or less regular basis, both from jaws and claws, sometimes (maybe to often) we get carried away with the fun and it gets "little" violent. If the wound is small and looks good then there is nothing to worry about. However if the skin around the wound turns dark/blue, normally the day after, you need medical care -> http://en.wikipedia.org/wiki/Sepsis Has never happend to me but I have seen it on a friend after a very nasty cat bite in the arm.

Maybe I have misinterpret the question, J.C.MacSwell will have to clarify... But I feel the question is not if a Newtonian Universe will collapse or not, the question is how fast a GR Universe will collapse if there is enough matter compared to a small locally collapse of matter in space. Since the main topic is Expansion Momentum, I assume he wants to know how the current speed of expansion will counter such a collapse.

J.C.McSwell: I apologize again, it was not my intention to bring Your thread off topic. Atheist: I am not in a position to be able to explain Professor Stephen W. Hawking's thoughts, in fact I asked for an explanation myself in this forum once. The interest was low, no one refuted or explained, so I might have ended up making wrong conclusions... Hawking's center of mass ? http://www.scienceforums.net/forums/showthread.php?t=10511

Yes, at least thats how I interpreted your question. Sorry, if I managed to get Your thread of track. It is a good question and I am also curious of the answer.

From "A brief history of time" by Stephen W. Hawking 1988: "If the numbers of stars was infinite and they where more or less evently distributed in an infinite space, wouldn't the universe collaps since the stars shouldn't have any center to be pulled against, according to Newton. This way of thinking is an example of errors of the mind when dealing with the infinite. The correct way to deal with this cind of problem - which people realized later - is to start with a finite solution and interpret how the situation changes when adding on more and more evently distributed stars outside this area. We can add how many stars we want and they will still collapse to one single body." From a more modern point of view you have to consider the shape of the universe, with a closed universe where gravity is stronger than dark energy, expansion will slowly halt and then reverse/contract. From Wikipedia "Ultimate fate of the Universe": "The fate of the universe is determined by the density of the universe. The preponderance of evidence to date, based on measurements of the rate of expansion and the mass density, favors a universe that will not collapse." But J.C.MacSwell assumes there is enough matter present to create a "big crunch".

I don't now any reson for the planes to be synchronized, when the systems form from clouds of matter they keep the momentum from the creation, which should be locally random. Most likely the planes are even rotating relative each other. The current difference between our system and Milky Way is about 60 degrees. The galactic disk has an estimated diameter of about 100,000 light-years. The distance from the Sun to the galactic center is estimated at between about 26,000 light-years and 35,000 light-years. It takes the solar system about 225-250 million years to complete one orbit. The periodic oscillation of the solar system, back and forth across the plane of the Milky Way galaxy, is about once every 30 million to 35 million years. We are only about 20 light years above the equatorial symmetry plane of Milky Way and have "recently" passed through.