Thinking and imagination have no limits. But if it is the space, then we can go beyond our imaginations, but with limitations. Yes, space travel comes with a boundary that we can’t cross. Even in science fiction, there is a limit beyond which you cannot go. There are the regions in the space that we can’t even touch actually. It seems strange, but it is true.
We are a part of our solar system, which is a part of our Milky Way galaxy. It is the spiral galaxy that has billions of massive stars, neutrons, gas clouds, asteroids, planets, moons, dark matter, black holes, and a supermassive black hole in the galactic center. It has a diameter length of about one hundred thousand light-years.
The Milky Way galaxy with Andromeda galaxy and fifty other galaxies forms a local group with a diameter of roughly ten million light-years. Hundreds of these local groups make a Laniakea supercluster. Millions of Laniakea supercluster grouped to form the observable universe. The question is, up to where can we go? – The Local Group.
Even if we develop interstellar travel (travel between the stars or planetary systems) we cannot go beyond a local group, which accounts for only 0.00000000001% of the observable universe.
What if we will not be able to develop interstellar travel? Still, can we travel up to the local group? The answer is, absolutely not.
If we send the probes and satellites to space, their travel will take thousands of years to reach the borders of the Milky Way. There are a few spacecraft named Voyager I and II, and New Horizons took more than 40 years to reach the edge of the solar system.
Therefore, we can say that even crossing the Milky Way galaxy will take thousands of years at the speed with which they are traveling right now. The local group is certainly large enough to travel right now, and unfortunately, we still have not figured out anything to go beyond our solar system.
What’s stopping us? Why can’t we be able to do that? There are certain economic, technical, and scientific reasons for this. We will discuss a few of them for a better understanding of space travel and challenges, which we need to encounter.
The nature of nothing
Space, which seems to be empty, isn’t empty actually. It has a tremendous amount of energy. That energy is the dark energy, which is the invisible force or effect that causes or speeds up the expansion of the universe. Well, we don’t have any idea about it, but we can feel its presence.
So, even if we bridge the gap between the two local groups, we can’t travel from one local group to the other group. The gravity is bound to us only for our local group. Outside the local group, the dark energy will act, which will leave us anywhere in the space, and we will not be ever able to reach our destination.
Once you leave the local group, you will get lost in the dark universe. At some point, the galaxies outside the local group will be so far away because of the expansion of the universe due to dark energy that even the photons will shift to such a long wavelength that they will be undetectable. So, leaving the local group isn’t a good idea.
The cost of doing it
We did a large number of space projects so far. We also have sent some humans to space at a distance of fewer than two light-seconds away. It costs us about a few billion dollars. NASA’s Apollo project’s today costs would be around $125 billion, a large amount to invest. Now you can imagine the cost of going too far in the universe.
It will be more than a few trillions of dollars. NASA is trying to build cost-effective robotic probes, drones, and satellites to explore the solar system. Well, maybe, in the future, we will achieve the outer space travel beyond the solar system with cost-effective science. But, crossing the Milky Way galaxy and the local group will be a challenge.
The time it will take
Space travel, even by a space probe, is time taking. Well, we are not able to achieve very high speed to compensate time. Voyager I space probe, which was being sent by NASA to study the outer space, has finally reached the outer space after 42 years of its travel. Currently, the Voyager is now only about 20 light-hours away from the earth, which means it has crossed the solar system.
At the rate of travel of Voyager I, it will take approximately 78,000 years to cover the distance of 4.37 light-years, which is the distance of the nearest star, Proxima Centauri. So, if we have to travel beyond the solar system, and far, we have to improve our technology so that the interstellar travel will not take thousands of years.
Is human ready for this?
If we talk about physical travel by a human being, at that moment, we are not able to go beyond the earth’s orbit. Astronauts have been to the moon. They are in the International Space Station. Apart from the cost, the human body is physically not ready for such harsh travel. The human body is sensitive to the change of the gravitational force, and due to the absence of it.
Even with a spacesuit, the body will go several changes like weakening of muscles and bones, the flow of fluids in the body, unconsciousness, etc. He could die if he goes too far in space. The human body is not ready for space travel, but the willingness to explore to go beyond the boundaries has always been a mindset of a human being. With this mindset, scientists are working to improve current technology.
But, we can go up to the edge of the solar system with the help of space robots, probes, and satellites just like Voyager I did for us. Maybe, in the future, we will have the technology to encounter such challenges.