A few questions about size and shape

[iDimension]

When science makes observations on the universe and combines those observations with common sense, at least for me it generates extremely peculiar results. For example if the universe is infinite, does this exclude the 'multiverse theory'? After all if an object is infinite, then that object is the outer most layer of something which can exist. A football and a baseball cannot both be infinite at the same time. If our universe is infinite, then everything which exists MUST be inside of our universe.

Secondly, observation tells us that the universe doesn't have an arc or 'horizon' so does this not support an infinite, shapeless universe?

I understand that science cannot publish anything without direct unequivocal proof but what constitutes as direct proof in the case of whether the universe is infinite or not? What are we looking for? What do we need to discover or know in order for a concrete scientifically backed answer?

Thanks.

 

[Mordred]

Space-time geometry is essentially an energy-density distribution relation, its a comparison of the universes actual density to its critical density. You can find the details here

http://cosmology101.wikidot.com/universe-geometry
page 2 is here

http://cosmology101.wikidot.com/geometry-flrw-metric/.

as far as multiverse theories goes an infinite universe does not preclude the possibility of a multiverse.

an infinite universe can be divided an infinite number of times and each universe can also be infinite.
multi-verse theories are at best sketchy though. There are so many theories, proposals etc that a straight answer cannot be given that would be accurate.

 

[bapowell]

Secondly, observation tells us that the universe doesn't have an arc or 'horizon' so does this not support an infinite, shapeless universe?

These observations pertain to the observable universe; we cannot extrapolate the apparent flatness of the local universe globally.

I understand that science cannot publish anything without direct unequivocal proof but what constitutes as direct proof in the case of whether the universe is infinite or not? What are we looking for? What do we need to discover or know in order for a concrete scientifically backed answer?

Science never proves anything. All we can do is assemble evidence that either falsifies or helps corroborates hypotheses. As for whether the universe is infinite or not, science simply doesn't know. All we can access observationally is a (likely) small part of what's out there. There have been some studies searching for the characteristics of a topologically closed (and hence finite) universe, but these have been inconclusive. For now, we must content ourselves with a limited understanding of the global geometry and topology of the universe.