Do Aliens Exist?
“Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.”
- Arthur C. Clarke
The word “Alien” comes from the Latin word “Alienus”, which is used to describe a stranger, a foreigner, or more broadly “belonging somewhere else”. However, the term alien has become more of a cultural depiction of something far more bizarre. Typically, the connotations of an alien are green or grey skin, big features (head, eyes, hands), wrinkly, and very often scary. As humans, we are built to fear the unknown, and so many writers and filmmakers have exploited this and used aliens as the centre of many horror books and films. The result of this is that now, not only do we have a natural tendency to fear aliens, but we seem to instinctively think that they are going to be hostile. Cultural depictions aside, I’m going to try and evaluate whether aliens may or may not exist, and in both cases what it means for humanity.
Possibility 1: We aren’t alone
If we assume all life evolves and forms in the same way and under the same rules as humans, regardless of where they are in the universe, then we have the powerful ability to look at the evolution of ourselves and extend that beyond Earth and explore the possibilities.
So, our estimates predict that the very first life on Earth (and thus our oldest possible “ancestors”) began to form around 3 billion years ago. However, this life was very unexciting. We were originally single-celled (prokaryotic) organisms, with the most exciting physical possibility being that we were probably some form of “sludge”. Yes, you are related to “sludge”. I mean, that shouldn’t be that much of a surprise as everything alive must have evolved from something. My favourite thought is that all organic matter evolved from the same point, therefore, you can look at anything “alive”, smile, and think “I’m related to that”. Who would have thought that the banana you just ate is actually your long-lost cousin (humans actually share about 50% of our genes with bananas!)
But back to the point. Although we began to appear 3 billion years ago, for about 2.8 billion of those years, we didn’t evolve much from that prokaryotic “sludge”. It’s only in the last 200 million years that our evolution has really put the foot down. So, of the time that life has been present on Earth, only a small fraction of the time has there been sentient life.
But the reason why this is important is that you get an interesting result from comparing this time to the “age” of the universe. It has been 13.8 billion years since the Big Bang. Although we are talking in the magnitude of billions of years, when you compare these time frames relatively, it seems that it’s taken a quarter of the age of the whole universe for life to get to the point where I am writing this blog post. And given the assumption I made at the start, this applies regardless of where you look. If it takes this huge fraction of the universe’s age to evolve, then the implication is that other life may indeed exist, albeit in “sludge” form. We imagine aliens as incredibly advanced beings that have the ability to visit Earth, but clearly, there is a massive chance that if they do exist, they are just still evolving. Although these “aliens” are rather disappointing, it is an incredible thought to think there may be other life out there. I guess at this point the answer to the proposed question is: “What do you mean by alien?”
Possibility 2: We are alone
Unfortunately, the logic explained above also works in the opposite way. The Earth has existed for 4.5 billion years, life has existed on it for 3 billion years, 2.8 billion years of which we remained prokaryotic. Given the universe is only 13.8 billion years old, there isn’t actually that much time for life to appear and evolve, so perhaps we are the only life?
But we must also consider one more factor: the conditions required for life to evolve. It’s no coincidence that we have discovered thousands of planets and found essentially none like Earth, and that out of all the planets we have discovered, life is only present on Earth. What I am trying to get at is that evidently, the conditions required for life to form are extremely specific, and don’t appear to happen very often. Well, given we haven’t found anything else like Earth, then we can (until proven otherwise) say that Earth is an anomaly. So, given that Earth is such an anomaly, and that even if there was another “life capable” planet, it takes in the magnitude of billions of years for life to form, then it wouldn’t be a surprise if we were the only life in the universe.
We don’t even know what the conditions for life to form are. If we say that water is the basis of all life, then it is strongly implied that there could have been life on Mars. Evidence suggests that Mars used to be warm and wet (it was literally covered in oceans). Not only that, but the evidence seems to show that Mars was in this warm and wet state for a longer period than it took for life to appear on Earth. You can check out my blog post “The Geological History of Mars” for more on this. If we can find evidence that life was present on Mars, then this is all the evidence we need to say that life is present elsewhere in the universe, and it is likely to be very abundant too. Given the size of the observable universe, if we can find life on our neighbour planet, then I’d bet my house life is elsewhere too (and a lot of it). However, so far we haven’t found evidence of life on Mars. So, if Mars used to be like Earth, and life didn’t appear, then it seems it is an anomaly for life to appear on a habitable planet, which in itself is an anomaly.
Conclusion
If life is present elsewhere, then my guess is it is unevolved. If other life is older than humans, then why haven’t we seen them? Hear me out. Look at how much humans have progressed over the last thousand years, and then over the past hundred years, and then over the past ten years. The rate at which our science and technology are growing is exponential. Look at medicine a few hundred years ago (they would literally cut slits on your arms to make you bleed out in an attempt to release “the devil” from your body which was causing your illness). Whereas now, we have incredible scanning machines, robotics, and drugs which are curing and fixing us up on a remarkable scale and incredible rate. Hell, look at technology. Show a 60-inch 4K OLED Samsung TV to some medieval peasant: humans are progressing at an unbelievable pace. But what does this mean? Well, given our increasing rate of progression in science and technology, imagine where we’ll be in a hundred years, or a thousand, or ten thousand!? And the universe, as I said, has been around for 13.8 billion years. So, if life is older than us by just 0.001% then surely, they’d be so much more advanced than humans that they would have come and visited us or something? If they were any older than that, then my god wouldn’t they be plastered all over the sky at this point? This idea is known as the “Fermi Paradox”. Therefore, my guess is that if life does exist, it must be younger than us.
The truth is, we still can’t conclusively explain how the first life on Earth formed. Did it land here on an asteroid? Did it spontaneously generate? Did something put us here (the basis of religion)? Until we can conclude how life forms, it is incredibly difficult to say whether or not it is possible for the same process to occur elsewhere in the universe. Or perhaps, there is something else we don’t know that explains why we haven’t seen other life. Maybe we are part of a contained experiment from another form of life? Or maybe life just doesn’t evolve in the same way elsewhere in the universe? Or perhaps other life has visited us, but governments are hiding it? At this point, we enter the world of conspiracy theories, and any extravagant guess you make is as good as mine… we just don’t know!
Originally published at http://thephysicsfootprint.com on February 20, 2022.
