The popular web portal Bigthink has calculated that even if humanity could travel at the speed of light, it would only be able to reach 6% of the galaxies within our observable Universe.
The universe itself is constantly expanding, and most galaxies have traveled enormous distances and continue to move away from us.
According to this analysis, no matter how long such a hypothetical journey would take, humanity would not be able to catch up with 94% of the galaxies.
From Earth, we can observe space objects up to 46.1 billion light years away. According to scientists, our visible universe contains about 2 trillion galaxies.
But at distances greater than 14.5 billion light years, galaxies are moving away extremely fast. Their speed decreases over time, but remains relatively high.
The reachable limit of the Universe is 18 billion light years from Earth.
If humanity began exploring the cosmos today at the speed of light, it could reach galaxies up to that limit. But that's only 6% of the currently visible universe.
Every year, about 160 billion stars, sufficient to form a small galaxy, move away from Earth to unreachable distances.
Thus, with each passing year, there are fewer and fewer cosmic objects that mankind can theoretically reach.
Source: Big Think