It is incredible to think that a few hundred years ago we believed that the earth was at the center of the universe. Now, we know this couldn't be further from the truth. As telescopes improved, we discovered new planets, solar systems, and even new galaxies.
Currently, we can see a large number of galaxies in the sky, but all of them are moving away from us. How is this possible?
About 100 years ago, astronomers Edwin Powell Hubble and Milton Lasell Humason realized that the galaxies in the universe are getting further and further away from our own. If you take two galaxies as a reference, you can see that the distance between them grows exponentially.
The galaxies are not exactly moving, but the space between them is multiplying rapidly, that is, the universe is expanding.
Why is this happening? The truth is that science has not been able to give a concrete answer to this problem. We only know that the expansion process does not affect gravitationally bound systems.
By this, we mean that the distance between the sun and our planet is not increasing, since the earth is pulled by the sun's gravity, for example.
The expansion of the universe is one of the great mysteries of physics today. However, it has also helped us learn a little more about the origin of our universe thanks to the Big Bang theory.
Now, it's interesting to think about what will happen when the space between galaxies is so great that none can be seen from the Milky Way. At that time, humanity will not exist, but any other civilization will only be able to see the stars in our galaxy and nothing else.