Are We Alone In the Universe?

"Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us." - Bill Watterson

Any article about life in the universe wouldn't make any sense without being introduced with the above quote. While a fun statement, it is flawed. As I'll explain in a moment, life in other parts of the universe may have already tried to contact us, but the message hasn't gotten here yet. It's something we think about a lot for sure, the question of whether or not there is life in the universe besides ours. Up to this point in our existence, there is no concrete proof to prove the existence of other intelligent life — or lack thereof. There are many theories, many ideas floating around that attempt to offer a comforting thought about life in the universe.

The caveat with these theories is that they are based on assumptions and scientific based guesses. Because no matter how hard we try, we've only visually discovered a tiny portion of the universe, and even that is an assumption. In order to understand or even comprehend the probability of even our existence, much less the existence of others, we can turn to the probability theory suggested by the famous British mathematician Roger Penrose. Penrose supposed that the odds against the existence of life on this planet were on the order of (10 to the power of 10¹²³) to 1. That's so massively unlikely it's almost impossible to fathom, but there it is.

So we could stop there and say that our creation was a complete accident and there is most likely no other life in the universe. However, the theories don't stop there and neither does our imaginations. While it's probably not like the scenario presented in Star Trek: First Contact where we have to buzz a passing spacecraft with our own warp capable spacecraft, it may have to be something just as drastic to get the attention of anyone out there. While that was science fiction, it's not unreasonable to assume that any other civilization out there is light years ahead of us in the advancement of their society.

Let me put it this way, our own galaxy - the Milky Way - is about 100,000 light years across. The Andromeda Galaxy, the closest galaxy similar to our own - is two million light years down the road. So let's assume that there is other intelligent life in the Andromeda Galaxy, and two million years ago they decided that they'd send a message out into space and see if anyone answers. Well, two million years ago was around the end of the Pliocene age. We were still halfway hunched over monkeys then, but there would be no way for them to know that. So say we got the message today. First off, how do we respond? Second, they would already be two million years more advanced than us and third, may not even exist anymore.

Even if we did have a way of communicating back, that would be a four million year round trip for the message. So we'd better have something damn good to say. I suggest a Chuck Norris fact.

Andromeda is the closest Galaxy that is constructed in a way similar to the Milky Way, that is, to support possible life. However, there could be many other galaxies outside of that, also constructed to support life. We just can't see them. Plus, the further out you go, just start tacking on the millions of light years. So whether or not there is other life out there, communicating with them might be a slight issue. Unless we are the advanced ones, in which case it'll be another two million years before we can reach out to them.

To fully suppose the possibility of other life in the universe we can apply the Drake Equation. Formulated by SETI founder and astronomer Frank Drake in 1961, the equation is a patchwork of guess work and supposition by Drake and his colleagues to predict life in the universe. Sadly, it is nothing but guesswork as some of the values cannot be known for sure, and are nothing but assumptions. It is basically meaningless, but cool to look at. To wit, the equation:

N = the number of civilizations in our galaxy with which communication might be possible;
and
R* = the average rate of star formation per year in our galaxy
fp = the fraction of those stars that have planets
ne = the average number of planets that can potentially support life per star that has planets
fℓ = the fraction of the above that actually go on to develop life at some point
fi = the fraction of the above that actually go on to develop intelligent life
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L = the length of time such civilizations release detectable signals into space.

The equation, with Drake's assumptions in place:

R* = 10/year (10 stars formed per year, on the average over the life of the galaxy)
fp = 0.5 (half of all stars formed will have planets)
ne = 2 (stars with planets will have 2 planets capable of developing life)
fl = 1 (100% of these planets will develop life)
fi = 0.01 (1% of which will be intelligent life)
fc = 0.01 (1% of which will be able to communicate)
L = 10,000 years (which will last 10,000 years).
N = 10 × 0.5 × 2 × 1 × 0.01 × 0.01 × 10,000 = 10.

So let's pretend all those numbers are nothing but exact. That puts the final value at ten. There are ten civilizations in our galaxy that we might communicate with. Where's Superman when you need him to fly around to all these planets and start knocking on doors? What this theory does is help to explain to our tiny mammal brains that perhaps we aren't all alone, that there may be someone else out there just as curious and confused as we are.

For the sake of further argument and putting you at ease with how singular we may be in the universe, let's do some further calculations based on assumptive theory. Let's assume there are roughly 50 billion galaxies that we can see, which isn't too far off from what we can see with modern telescopes. In each of those galaxies there are billions of stars, billions. I know after hearing about our national debt for so long, that number value has less meaning, but stick with me here.

Take those billions of stars, actually somewhere around 70 sextillion as supposed by the General Assembly of the International Astronomical Union back in 2003, and suppose that one in a million of those stars is in a working planetary system. Then, let's say that one in a million of those has a planet that supports life (an "M-Class" planet, as they'd say on Star Trek). So being lazy and not taking out my calculator, that's what, in the tens of billions still? It's all hyperbole anyway, but if you were feeling alone you can take those assumptions and feel a little better.

Of course, in the end, there's no way to really tell at this point whether or not we are truly alone. I think it's a bit arrogant to think that we are that special to be the only form of intelligent life in the universe, but hey, until we're shown otherwise (ie: when the invasion starts) why not be selfish?

Image credit: NASA/Swift/Stefan Immler (GSFC) and Erin Grand (UMCP)
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