A contradiction ?

[Wellsi]

My dad asked me the other day... if space orginated from a big bang as we think... does that not mean it is expanding outwards? How can it be expanding if it is infinite already.

I couldn't answer him there and its a serious paradox in thinking. So where is he wrong and what's the go with that?

 

[russ_watters]

It may or may not be infinite, but that doesn't affect whether or not it can expand. Infinity is not a number. It isn't a limit.

 

[Wellsi]

infinity is just a concept right... wow i actually learned that from maths. :)

The density affects whether it expands or not right? Omega is less than/ equal to or greater than 1 idea... and the triangle drawn onto that sheet of paper?

 

[Aschere]

The density affects whether it expands or not right? Omega is less than/ equal to or greater than 1 idea... and the triangle drawn onto that sheet of paper?

The gravitational influence of everything in the universe decides whether or not it keeps expanding (which it will) What you're talking about is, i think, the shape of the universe (saddle, sphere or flat). Dark energy gives us how fast it's expanding.

 

[matt.o]

Dark energy gives us how fast it's expanding.

Not quite. The Hubble parameter tells us the change in scale factor (ie. the rate of expansion). Dark energy is the label given to whatever it is that is causing the expansion to accelerate at the present time.