We know about things; do things, have devices; are furthering science and knowledge in ways that were unthinkable a hundred years ago. To rule out any possibility just because we don't understand how it can be true or untrue is the height of arrogance. They have "discovered" the end of the universe several times in my lifetime alone, and each time they build a newer, bigger and better telescope they do it again. The Periodic Table of Elements keeps getting bigger. We are on a continuum, not at the end, maybe in the middle, or even just at very close to the beginning. Speaking in terms of, "We know this or that to be true.." needs to be rarely used and replaced with, "We think blah, blah...".
Even the color spectrum is not absolute. It all depends on the ambient light in which one views it, and individuals "see" colors differently. On another planet with a different sun, who knows? Outside of mathematics, there may be very few absolutes.