If the universe is expanding, what is outside it? If there is nothing outside it, how does it expand to create void?
Answers
If the universe is expanding, what is outside it? If there is nothing outside it, how does it expand to create a void?
There is nothing outside our universe. If there were, it would be incorporated into our universe and then again there is nothing outside our universe.
A void is a space with nothing in it. Our universe has no voids in it. Pick any volume within our universe and you will find something in that volume. You will find some CMB at very least. Outside of our universe there is nothing…certainly no CMB . NOTHING. So our universe does not create any voids. Actually our universe hates voids. finds them appalling and if ever a void showed up in our universe it would be filled at the speed of light.
Our universe is composed of physical space, matter and energy. Without matter and energy there is nothing, a void. So physical space is the space that separates things. without the things there is no physical space. connect any two objects with a line. that line spans the physical space between them. you cannot have physical space unless it is contained between objects. outside of our universe there are no objects so there is no physical space.
Our universe does not create voids. There are none within our universe and all that is not in our universe is a void. Since that void is totally empty and contains nothing there is nothing to prevent the objects in our universe from moving away from each other. And they do move away from each other.
In order for something to have a shape it must have a boundary. Since the universe is bounded by nothing, it cannot have a shape. There is a lot of discussion about whether the universe is flat or concave or convex: what is its geometry?
There is lots of speculation. But a geometry is a shape and since the universe has no shape these speculations are a form of mental cosmobation.
Occam's razor suggests that if everything is moving away from everything else there must be a center to all of it. To have a center we would need another physical dimension. Like a balloon with a 3 dimensional surface expanding in 4 dimensional space. That is the simplest view. But since a 4th dimension cannot be demonstrated through experiment the idea is avoided. this suggests the myopia of today’s view of physics.
Khadijah21
Answer:
But no matter what shape the universe is, it's not expanding into anything. There's nothing outside of the universe because the universe has no edge.