©Saurav Baglari
Is there a barrier we can never cross? Are there places we’ll never reach, no matter how hard we try? How far can we go? What are the Limits of Humanity?
Turns out, there are places we won’t ever reach; things we won’t ever find. Even with science fiction we are trapped in our pocket of the universe.
We live in a quiet are of the Milky Way, a spiral galaxy which is of average size i.e. about 100,000 light years across, consisting of billions of stars, gas clouds, dark matter, black holes, neutron star and planets; with a supermassive black hole in the galactic centre (Sagittarius A). From afar, our galaxy seems dense but in reality it is mostly empty space. With our current technology, sending a human to the closest star would take thousands of years. Thus, our Milky Way galaxy is pretty big.
However, it isn’t alone though. Along with the Andromeda and more than 50 dwarf galaxies, it comprises the ‘local group.‘ The local group is a region of space which is about 10 million light years in diameter. It is one of hundreds of galaxy groups in the Laniakea Supercluster; which itself is one of millions of superclusters that make up the observable universe.
Now, let’s imagine we, humans, have a bright future. Say, humanity becomes a type-3 civilization, does not get wiped by aliens or due to some galactic disasters; and develops interstellar travel based on our current understanding of physics. In this best-case-scenario, how far can we go?
Well, the Local Group. It is the biggest structure or community that humanity will ever be a part of. Even though it is huge, it accounts for just 0.00000000001% of the observable universe. Try imagining this number, and let it sink in. In simple words, we are restricted to a 100 billionth of a percent of the observable universe. The fact that there is a limit for us and that there is so much of the universe we will never know of, is kinda frightening.
Why can’t we go further? Let’s go back to the beginning of everything. Yes, 13.8 billion years ago, when the fabric of space consisted of nothing at all. Right after the Big Bang, in an event known as the Cosmic Inflation, the observable universe expanded from the size of a marble to trillions of kilometres in just mere fractions of a second. These event was so fast and extreme that even the quantum fluctuations were stretched as well, and subatomic distances became galactic distances.
After inflation, gravity started to pull everything back together. At the larger scale, the expansion was too quick and powerful to overcome, but at smaller scales gravity emerged victorious. So, overtime, the pockets of the universe grew into groups of galaxies like the one we live in today. Only stuff inside our Local Group is bound to us gravitationally? So, what’s the problem then? Why can’t we travel from our pocket to the next one?
Here, dark energy makes everything complicated. About 6 billion years ago, dark energy took over. It is basically an invisible force or effect that causes and speeds up the expansion of our universe. We don’t know why or what it is. But we can observe its effects clearly. We are surrounded by a lot of stuff but none of those structures and galaxies outside the Local Group are bound to us gravitationally.
So the more the universe expands, the larger the distance between us and other gravitational pockets becomes. Overtime, dark energy will push the rest of the universe away from us; thus, making all those clusters, galaxies and groups eventually unreachable. The next galaxy group is already millions of light years away but all of such groups are moving away from us at speeds we can’t even hope to match. We could leave the local group and fly through intergalactic space into the darkness, but we would never arrive anywhere.
As we would become more and more stranded, the Local group will become more and more tightly bound, and merge to form a giant elliptical galaxy, with an unoriginal name: Milkdromeda, in a few billion years.
But, it becomes more depressing. At some point, the galaxies outside the Local Group will be so far away that they will be faint to detect. The few photons that brought us info would become undetectable as they too will travel much longer distances. So, it is safe to say that, the beautiful night sky filled with stars that we enjoy today, will be nothing but completely dark in a few billion years. It will appear dark in all directions, forever.
The future beings of Milkdromeda will think there’s nothing but its own galaxy in the entire universe; they won’t be able to see Cosmic Background Radiation, and they won’t be able to learn about the Big Bang. They’ll think the universe is static and eternal. Milkdromeda will be an island in the darkness, slowly getting darker and darker.
Still, with its trillions of stars, the Local group is still large enough for humanity. After all, we still haven’t left our Solar System yet and we still have billions of years to explore our own galaxy.
We exist at the perfect moment in time, to be lucky enough, to see not only our future but also our most distant past. As isolated and remote our Local Group is, we can perceive the entire universe, grand & spectacular, as it is right now.
*Written by: Saurav Baglari*
Lost Writer 