In this post, I want to continue, in a more limited way, from the post I made last week, about traveling the universe, or at least our Milky Way galaxy. Last week’s post was about why we haven’t been visited by aliens from other planets, and I gave some reasons why this hasn’t taken place. One of my favorite theories about this is that the distances between star systems is so great and so immense that simply traveling them is untenable, or at the very least, unlikely with the technological systems we have and understand here on Earth at the present time. For example, the nearest star system to Earth is the Alpha I & II/Proxima Centauri system, 4.37 light years away. As I write this, the Artemis II spaceship has just returned to Earth from an amazing flyby of the moon, and it took them farther from Earth than any human has ever gone. Well done, guys.
But compared to traveling the galaxy, that’s a puny trip, miniscule in its distance traveled. If we were to try to travel to the nearest star at that same speed those astronauts went, and we tried to do it by using only the same rocket power they used, that trip would take thousands of years. That’s ridiculous on the face of it. How would they take enough fuel to make the trip, or carry enough food and water, or rid itself of wastes over the whole distance? It’s not like a trip on the interstate where gas stations and restaurants are available at intervals along the way. Could you ask some astronauts to begin a trip like that knowing they would live out the rest of their lives on the ship, and that their descendants will live and die in that ship for hundreds of generations, just to reach the nearest star? Such a trip is unlikely and unrealistic even from its very conception. I imagine somewhere along the way, at some level of procreation, they’d go mad and destroy themselves well before they got there. It’s possible a new form of propulsion will be developed in the future and make that trip realistic, but at this time I don’t know what it will (or might) be. It will have to be powerful.
So, if interstellar travel is ever possible, it may wind up being under circumstances that we cannot conceive of right now. By worm hole, perhaps?
Any civilization that can make such a trip will have to be much farther advanced than we are. Let us define such a civilization as populated by a species that can utilize that kind of spaceship that can travel between star systems as easily as we travel the interstate. We would have to call them a “superintelligent species,” who have developed forms of travel we haven’t begun to think about. Science fiction produces these kinds of species with amazing regularity, but science fiction isn’t reality (for obvious reasons) and that doesn’t mean that because a fictional character goes off to, say, Betelgeuse to watch the coming supernova, that we can also do so in in real life. We’ll just have to watch it from our position here on Earth. (It’s safer that way, anyway.) Admittedly, I have used some of these unrealistic forms of propulsion in my sci-fi novels, not because I expect it to actually be developed someday, but to move the plot along. I don’t want to keep my characters trapped inside a spaceship for thousands, or tens of thousands, or hundreds of thousands of years, doing nothing but waiting to get where they’re going. That’s not good plotting.
All of this helps explain why, or at least one reason why, we haven’t been visited by aliens from outer space. The distances are so huge, that, in the absence of some form of power we don’t know of, it’s just too far. Can you imagine trying to travel to another galaxy by just using rocket power?