A general qustion on expansion

[mubashirmansoor]

A general qustion on expansion...

Hello,
As I was thinking about the expansion of the universe I couldn't understand a specific part of it which is if the space time dimensions are increasing in size or not(being under a geometrical streach). Once I heard that the expansion of the universe and the increasing distance between the galaxies is just like a balloon filing with air and that the galaxies are like the points on the surface of the ballon... Acoording to this example I thought that the universe is actually under a streach... So that means we are increasing in volume each second but as the expansion is uniform to evrything and that relative to us evrything will be seen the same... I'm not a professional, so I'd be glad to know what is really going on... :)

The module I mean is attached to the post.
Thankyou once again.

 

[lippyka]

The answer to your question is that the space-time dimensions are not actually increasing in size, but instead the galaxies are moving apart from each other due to the expansion of space. The expansion of space can be thought of as stretching out the fabric of space-time, like a rubber sheet being stretched out. The galaxies remain at their fixed positions on the sheet, but the distance between them increases as the sheet is stretched. Therefore, the expansion of the universe does not involve an increase in the size of the space-time dimensions, but rather an increase in the distance between galaxies.