How can scientests be so sure that space has no end?

Question

I just find it hard to believe that space is boundless - can we really ever be sure?

Answer 1

http://www.sciam.com/print_version.cfm?articleID=0009F0CA-C523-1213-852383414B7F0147

cosmologists use observational evidence to construct mathematical models, then they make predictions based on these models. if they then see these predictions then they can be more sure that the model is somewhat accurate, but if they then find that they do not see the predictions then they must revise the model.

the universe is four-dimensional, but if you can imagine a two-dimensional version then it seems to be something like the surface of a sphere. it is this surface that is expanding. it is finite in size yet has no center and no edge. nothing, not even space-time seems to exist "outside" the universe.

incidentally, the universe began about 13 700 000 000 (13.7 billion) years ago, and the expansion of the universe increased suddenly for a tiny fraction of a second when it was still only a slightly bigger tiny fraction of a second old. this is called the inflationary period. at the end of this period, the universe was about one meter across. after this super-fast expansion, the expansion rate began to slow.

when the universe was about 380 000 years old, it had expanded and cooled enuf for free electrons to combine with atomic nuclei to form atoms (about 74 percent hydrogen and 26 percent helium). light was then free to pass unscattered by the free electrons so the universe became transparent. before this time, the universe was much like a heavy fog. today, we see this light stretched to microwave wavelengths, and we see it in every direction we look, but the universe was much smaller then than it is now. this is the cosmic microwave background. even tho the universe is 13 700 000 000 years old, the cmb is at least 46 000 000 000 light-years away.

http://en.wikipedia.org/wiki/Physical_cosmology
http://universeadventure.org/
http://www.astro.ucla.edu/~wright/cosmo_01.htm

Answer 2

Actually, the shape and extent of the universe are among the many things that science is not sure of. Space can be boundless without being infinite, if it curves back on itself. This is hard to visualize, but it's similar to the way a circle is endless, even though it has finite size.

Answer 3

Let's imagine for a minute that our universe is "finite",or having a definable limit or border.
How would you know where the border is? It would have to be recognizable somehow.You need to see a thing (in your example,our universe) as a whole to know what its boundaries are.But you would have to be far enough away from it to determine this! How would you accomplish THAT?!
The truth is that we only have THEORIES about the extent of our universe.A good number of scholars argue about the size and form of our universe,but in reality we just don't know.We're only human.Even with all of our technological advances,we are bound by our own limited understanding of things.We just don't have the ability to step outside of the picture in a manner that lets us view it as a whole.

Answer 4

Some scientists think that space has an end. They are not sure about most things.

Answer 5

Space is a property of any two reference points or physical phenomena: it is the distance between them. As the property of distance is an idea - not physical - it is actually not bounded by physicality - it is in the realm of ideas. As ideas themselves are boundeless, so must be space - an idea, which by definition (of an idea) has no physical boundary.

Don't let the distraction of observing the space between two objects distract you from the otherwise independent notion of distance, or it's emergent structure: space.

In another perspective, if one defines any boundary to space, he or she is simply defining a reference frame - and not space itself. Note that reference frames are confounders to the study of space, but not space itself. And, thus, space has no bounds (lest we be in a reference frame). In other words, "space," can be defined as that inside AND outside reference frames; be careful though, not to define what's outside - you'd again be defining a reference frame not space.

Any constraints imposed on the definition of distance from the physical (not reference points - which are free from direct physicality) Universe become properties of identifiable physical entities, and thus is not distance itself. Space is that which is distance, and thus trully independent of physicality.

Answer 6

We could not really be sure. Yet you don't need to be there to prove to yourself that the statement is true. Just like "All men are mortal", do you have to kill everyone to prove your point?
As far as the eye can see...space goes far beyond that.

Answer 7

They can't. There are lots of things scientist can't be sure of.