We Need Warp Engines Now Scotty!
Did you know that there was a cosmic speed limit? This speed limit is the speed of light, and there was a time when it was considered that nothing with mass could travel at or beyond this speed. It would appear that several things out there are speeding. One of these things appears to be space itself.
13.8 billion years ago the big bang occurred. There was a time after this called inflation. During this time the universe expanded exponentially over a very brief period of time. Over the billions of years of a much slower expansion the universe is so large we can't see the end of it, nor will we ever. This begs the question if the speed of light is a cosmic speed limit, how could there possibly be regions of space forever out of reach. It's not traveling faster than the speed of light is it? Short answer yes it is.
As is known by the many Potatoes out there everything in the universe attempts to exist in the lowest possible energy state. However in infinitesimally small amount of time after the Big Bang many scientists believe that the cosmos was at a state of rest in what is called false vacuum energy. In this incredibly tiny span of time the universe increased in size by a factor of 10 to the 50th power. That's big and fast.
Almost expansion has occurred since this time it has been at a much slower rate. As stars emit photons or galaxies grow and move across the universe this stretching causes them to lose energy when the photons reach Earth their wavelengths have been red shifted dependent upon the amount of distance they have traveled. This redshift can be measured and used to determine the distance that the light traveled and therefore how far away the celestial body is.
This shift in light allows earthbound scientists to see objects like stars or galaxies as they existed in the distant past. It would seem however that as our cosmos is ever-expanding that some objects are simply too far away first you ever see the light that emanated from them.
This means that some aspects of our universe will remain mysterious forever. Our observable universe lives on one side of what is referred to as the particle horizon. This is what marks the distance to the farthest light that we can see at this moment in time. This means that light waves have had time to either catch up to, remain within, or spam beyond the sphere.
In order for us to see beyond the particle horizon it will become necessary for our scientists to be able to travel faster than the speed of light. This would allow us to "catch up to" the particle horizon and see beyond it. In order to do this we will need to either find a way to cause mass to travel faster than the speed of light or warp space-time and a way for us to close the distance instantly. Although theoretically possible neither are currently in the works.