Two major themes or ideas that have permeated science fiction for decades are aliens and developing the mysterious technology that will allow humanity to travel between star systems with ease. Funnily enough, as a small kid I always imagined it was simply a matter of time before these things would become a reality. Aliens would of course one day visit us and we would shake their hands and have parties. Obviously FTL drives would then be invented and we could go on interstellar holidays. As you get older though and you learn more about the universe and how vast it is you begin to realize that these things are rather unlikely, which is putting it mildly. Many people postulate the idea the existence of aliens in some form is likely given the size of the universe. Others cling to obscure mathematical models that don’t technically conflict with the laws of physics (as we understand them) to keep their dreams of travelling to other stars, with flight times of less than a century, alive. Are such things possible? And if they are, will they have any impact on humanity in any practical way or will these ideas be doomed to remain as the subject of our dreams?
While I am not a astrophysicist, rocket scientist, or a xenobiologist, I still enjoy discussing such things and am doing so for nothing more than fun and to hear other peoples points of view. Feel free to correct me if I have made a mistake as I fumble about in ignorance of the truth. In all fairness though, even the forefront of science knows relatively little about such things which is why it is still fun to talk about!
I think it is always important to preface this discussion with a rough outline of what we are dealing with. Firstly, I fully understand that interstellar travel and FTL are two distinct subjects. I am talking about practical interstellar travel here, not starting out on a journey so that your great grandchildren might get to see some dead planets around a star. We could send some people out on slow ship with the idea that a few generations down the line will be alive when the ship reaches the destination. I think this introduces too many moral/ethical dilemmas for it to be considered. How can we doom generations of people not yet alive to live on a ship and not see their home planet? We also force them to take part in an incredibly dangerous mission they never signed up for. For that reason, I am linking the two ideas as FTL or near light speed travel are essential for practical interstellar travel. There is also preservation of the body while travelling, but you would still need to travel quickly. I don’t consider it very practical when centuries have passed while you have taken your holiday. Secondly, we need to appreciate that the universe is incomprehensibly massive and that the distance between our sun and even the closest star is vast when compared to the distances our brains are used to thinking about. Proxima Centauri (the nearest star and exoplanet) is approximately 9,000 times more distant to us than Neptune. When you consider that there are billions of stars in our galaxy and billions of galaxies in the universe your brain starts to do somersaults.
Now we can begin!
There are great thinkers out there who postulate that given the size of the universe, alien life is highly likely. This makes sense to us from a statistical point of view whereby something is likely to occur again given a large number of trials or events. The easiest thing to compare this to is the lottery. While it is extremely unlikely that you will win the lottery, it is still highly likely that someone will given the number of people that have purchased a ticket. The extremely unlikely event of an individual person winning will also happen again and again for the same reason. This logic coupled with the ideas that Earth itself does not occupy a unique position in the universe, and that life here is not special, could mean that there are countless worlds with alien life out there. The trouble is, we don’t fully understand the probabilities involved as we don’t yet fully understand how life came to be, or how likely life is to occur with differing conditions. We therefore do not understand how rare life actually is.
Assuming this way of thinking is fundamentally correct in its application, which is a rather major assumption as there are many things about the nature of the universe we do not understand, I still don’t think it really matters. Intelligent life is likely to be much much rarer meaning that in most cases you would be encountering microbial life. And then even if there is a small scattering of intelligent life out there, we will never meet. Why? Well because we can’t reach them. We not only need to meet them in space, but also in time as well. Consider that intelligent life on Earth has only existed for a micro-fraction of the total time that life has been on Earth. If aliens were to have visited our planet, it is more likely they will have introduced themselves to dinosaurs rather than humans. Hmmmmm how did the dinosaurs die out exactly? Haha only joking …although that might be an awesome idea for a book! Blowing apart dinosaurs with laser beams!
In order to take interstellar holidays and visit our alien friends we need some fancy starships equipped with buzzy-whizz-bang things that either make you go very fast or bend and manipulate the fabric of the universe. Unfortunately it’s not a simple matter of jamming enough fireworks onto the back of a skateboard. Even exploding atomic bombs to propel you through space isn’t enough! The sad thing is physics tells us that going faster than the speed of light is impossible and that going close to the speed of light requires an absolutely ridiculous amount of energy.
The first thing most people of think of is the Warp Drive, otherwise known as the Alcubierre Drive. The idea is that the ship will contract space in front of it and then expand space behind it. This would allow the ship to effectively travel faster than light without traveling faster than light. Sounds weird right? You are moving slower than light, but because you are locally manipulating the size of the space you are moving through you will reach your destination faster than light will that is travelling through unwarped space. This technology is used widely in science fiction and is the method used by ships in Star Trek. Sadly this tech would require exotic matter that may or may not exist and also appears to conflict with quantum mechanics. Damn it physics! Stop destroying my hopes and dreams!
Wormholes are also often used in science fiction as a method of interstellar travel. The idea is that a tunnel forms between two points in space-time which you can move through. The two points in space-time could be light years apart which would allow us to move between solar systems with ease and, in a sense, exceed the speed of light. Although wormholes are theoretically possible, it is not known whether they actually exist. That’s a bit of a bummer. I read that wormholes could even extend between different universes. Imagine if your wormhole malfunctioned! “Damn it, wrong universe …um okay, now how do I get back…”
Wormholes are used extensively in science fiction. Peter F. Hamilton makes use of wormholes in his Commonwealth Saga and a wormhole also featured in the hit movie Interstellar. Wormholes also feature heavily in the popular Stargate TV series. Wormholes occur in The Forever War by Joe Haldeman which was written when it was thought they might occur inside black holes.
There are various other ideas and theories milling around out there; black hole starships, antimatter rockets, ion drives, tachyons, hyperdrives …all are interesting to read about and discuss but are too numerous or detailed for me to take the time to discuss them here. Feel free however to include anything you’ve picked up in the comments section!
Of course there is always the minuscule possibility that we have it all wrong. Aliens are on their way and will be here by noon tomorrow. NASA is going to unleash their starship full of whizz-bangs any day now. It’s fun to think like this. And that is why I still enjoy picking up science fiction books and reading them.