What’s at the End of the Universe? Here’s Journey to the End of the Universe
The universe, as far as we can tell, has no edge. Space spreads infinitely in all directions. Also, galaxies fill all space throughout the entire infinite universe. This conclusion is reached by logically combining the two observations.
First, the portion of the universe we can see is uniform and flat on the cosmic scale. The uniformity of the universe means that galaxy groups are more or less evenly distributed on the cosmic scale. The flatness of the universe means that the geometry of space-time is not curved or curved on the cosmic scale. This means that the universe does not wrap and self-connect like the surface of a sphere, resulting in a finite universe.
The flatness of the universe is actually a result of the uniformity of the universe, because dense collections of mass cause space-time to curve. Moons, planets, stars, and galaxies are all examples of dense collections of mass, and so they do indeed bend space-time in the space around them. However, these objects are so small compared to the cosmic scale that the space-time curvature they cause is negligible at the cosmic scale. If you average all the moons, planets, stars, and galaxies in the universe to get a large-scale expression for the mass distribution of the universe, you’ll find that this is constant.
The second observation is that our corner of the universe is not special or different. Since the part of the universe we can see is flat and uniform, and our corner of the universe is not special, all parts of the universe must be flat and uniform. The only way the world can be flat and uniform literally everywhere is if the world is infinite and has no edges. Although this conclusion is difficult to understand to our feeble human mind, it is the most logical one according to scientific observations. If you fly a spaceship in a straight line forever through space, you will never reach a wall, border, edge, or even a region of the universe without groups of galaxies.
But if the universe was created in the Big Bang, how could it not have an edge? If the universe started out as finite in size, shouldn’t it still be finite? The answer is that the world did not begin as finite in size. The Big Bang wasn’t like a bomb exploding on a table and expanding to fill a room with debris. The Big Bang didn’t happen at one point.
It happened all over the universe at the same time. Therefore, the remnant of the Big Bang, the cosmic microwave background radiation, is ubiquitous in space. Even today we can look at any corner of it and see the cosmic microwave background radiation. The explosive expansion of the universe was not the case of a physical object expanding into space. Rather, it was a case of space itself expanding. The world started out as an infinitely large object and evolved into an even larger, infinitely large object. Although infinity is difficult for humans to understand, it is an extremely valid mathematical and scientific concept. Indeed, increasing the size of an infinitely large being is a perfectly reasonable concept in science.
Remember that people can only see some of them. We call this piece the “observable universe”. Since light travels at a finite speed, it takes a certain amount of time for light to travel a certain distance. Many points in the world are so far away that the light coming from these points is the same as the universe’s. Since its inception, it has not yet had enough time to reach the world. And since light travels at the highest possible speed, that’s it.
It means that no information or signal of any kind has time to reach the earth from these distant points. Such locations are currently basically outside of our field of observation, that is, outside of our observable universe. Every place in the universe has its own field of observation, beyond which it cannot see. Since our observable world is not infinite, it has an edge. This does not mean that there is an energy wall or a giant abyss at the edge of our observable world. Edge is simply where earthlings can see right now. It marks the dividing line between places we can’t see right now. And although our observable universe has an edge, the universe as a whole is infinite and has no edge.
As time progressed, more points in space had time for their light to reach us. Therefore, the size of our observable universe is constantly increasing. Therefore, you might think that after an infinite time it will be observable to all. However, there is a complication that prevents this. It is still expanding. While the current expansion of the world is not as rapid as it was during the Big Bang, it is equally real and important. As a result of its expansion, all groups of galaxies are constantly moving away from each other. Many galaxies are so far from Earth.
Its expansion causes them to move away from the earth at a faster-than-light speed. Special relativity prevents two local objects from traveling faster than the speed of light relative to each other. As a result of its expansion, it does not prevent two distant objects from moving away from each other faster than the speed of light. No matter how long we wait, as these distant galaxies are moving away from Earth at a faster-than-light speed. The light from these galaxies will never reach us. Therefore, these galaxies are always outside of our observable world. Another way of saying this is that although the size of the observable is increasing, its actual size is also increasing. The observable limit cannot keep up with its expansion, so many galaxies are forever beyond our observation. Despite this limitation in his observation abilities, he still doesn’t have an edge.