We do not know for a fact that space is infinite. Light is what we use to explore distant space, the light from stars. We know how fast light travels, so if we know how far away a star is, we know how long ago the star put out the light. From motion of the Earth, looking at a star at different times of the year, we know how far away the most distant galaxies we have ever seen are located. These are stars just coming into being, very young stars. This causes scientists to believe that there aren't many stars beyond. Still, they could be. It is possible that a very distant set of galaxies exists on itown, too far away for its light to have reached us yet. We do not know for sure. Until there is something to indicate its existence, scientists will try to explain things without it. Scientists prefer to use the simplest models possible that still agree with reality. I doesn't even metter is it or is it not space infinite. What matters is that there is infinite beauty in space. A piece of that beauty we will try to capture.