Sarpedon

The universe is not limited by physical barriers. It is limited only by the extent of Time and Space. General Relativity explains that these are the same thing. They are also believed to be produced by mass and energy. So...beyond a certain distance (which I don't know) from objects with mass and or energy (the two also being basically the same) space and time do not exist. therefore the universe is limited by the phemonenon that space and time exist only around mass.

Seraphim

The universe is not limited by physical barriers. It is limited only by the extent of Time and Space. General Relativity explains that these are the same thing. They are also believed to be produced by mass and energy. So...beyond a certain distance (which I don't know) from objects with mass and or energy (the two also being basically the same) space and time do not exist. therefore the universe is limited by the phemonenon that space and time exist only around mass.

My reply : I think I can understand this. Space can be understood by logic but Time ... I thought Time is constant no matter where you are.

I think the limitation of Time and Space is like water, poured onto the floor and spread in all direction to a certain length before stopping due to its own quantity. It cannot spread more because it's quantity (which in this context is the Mass of whatever started the Big Bang) is to a certain limit and it will break up when it spread more. Is this a logical assumption?

Sarpedon

According to accepted physics, time is similar in space in that it can be distorted by mass and motion. When moving at great speeds, time seems to slow down, and space is foreshortened. Nearby to objects with mass, both time and space are distorted. We experience the space distortion as gravity, but the time distortion is much more subtle. But I do believe that it has been measured. try visiting some science websites, you can find better sources than me.

As to your second question, the fact that galaxies are zooming away from each other at an ever increasing speed, scientists postulate that eventually this speed will reach the speed of light, and the galaxies will become, for all intents and purposes, seperate universes. It is possible that this increasing speed is a result of a time distortion between the galaxies. As the mass gets further apart, the space-time between them gets more stretched, and eventually (when the relative speed reaches the speed of light) the connection snaps, leaving two bubbles of space-time which are completely separate.

(caution! I am not a physicist! If any scientist contradicts me, believe him!)

andy_d

I remember reading that somewhere too. They stuck two atomic clocks at the top and bottom of a very tall building and left them to run for a while. Eventually there was a slight discrepancy due to the difference in gravity. Gravity is simply accelaration, so causes the same effects as motion.

Basically time, like space, is relative. Clever bloke, that Einstein.

It's actually more correct to say that they are the same thing. You can't have just space or just time, you have to have both: Spacetime. If one is relative, the other one must be, because they're actually different properties of a single phenomenon.