Today, during work, I was reading the space special of a popsci magazine called KnowHow. I have a weak spot for these kind of magazines, being interested in science but not educated in it. In this space special, that was created for the NASA exposition that`s coming up in Utrecht soon, there was an article about the search for extraterrestrial life. It mentioned all the typical arguments for why certain planets can or can not inhabit life.
A lot of the arguments for planets with possible life on them were as following:
-the planet needs to have some sort of solid ground (so not gas as with Jupiter)
-there needs to be a proper atmosphere
-there needs to be oxygen
-the gravity levels have to be similar to earth
-there has to be water
-it needs to be the correct space (i.e. earth-like) away from the sun. Not too close, not too hot.
And like this there are many more requirements before a planet even gets considered.
I`m not even sure where to begin with “this is stupid”. There is no guarantee alien life actually has the same requirements as we do. We don`t know if the micro organisms all life on earth evolved from are themselves even from earth or space. They might have evolved from a chance development between several building blocks like amino acids, that are found in space as well. But isn`t there a really big chance everything evolved the way it did because of how earth is, instead of earth providing the perfect environment?
This logic aside, I do see why scientists work like this. You need a starting point, you need to exclude planets and focus on other, more likely ones. But are they really more likely?
To the basis of all this is a very fundamental, even philosophical question: how do you define life?
Think about it. How is life defined? By having a beating heart? Plants and trees don`t have hearts. Is it defined by how much gravity (and thus pressure) it needs/can handle? There are many creatures on the bottom of the ocean, where humans would be crushed, that thrive there with insane amounts of pressure and no light. Is life defined by having some sort of conscience? By being able to move? By growing? By dying at some point? There are animals and plants living up to thousands of years and still going strong.
And here lies the very problem: life as it is, is extremely difficult to define. And I suppose scientists are doing a decent job if they look at what micro organisms and bacteria need in order to survive, when looking at possible planets. But I`m pretty sure these little critters can survive everywhere, even in the harshest of conditions. Life has a tendency of surprising us, of surpassing logic.
I think we need a more open mind in the search of alien life. Alien life could be anything, not just what we define as life. It`s hard to imagine anything else, just like it`s hard to imagine there are colours we can`t see because we don`t have the colour receptors for them. But it`s still going to be necessary if we want to actually find alien life.
Speaking of a more open mind: I also read that a lot of people consider the lack of contact proof that life doesn`t exist anywhere else.
Again: where do I even begin.
We assume (again! Enough with the assuming! We`re talking about alien life here) that aliens know how our radio systems work. We assume they can pick up our signals, and know how to decipher them. We assume they have a way to listen to our messages, or a way to see our pictures. They might not even have sight for all we know. And even if they do see/hear us, we have no means of knowing if they understand the message, or have a way to respond. They could be like us, sending us messages except that we don`t have the right technology to pick up their messages.
I guess, what I`m trying to say is that, try as we might, I consider it very unlikely that we`ll ever pick up anything with the way we`re handling things now. We have a better chance at finding alien life, once we get out there and see for ourselves. It will take a while longer, yes, but I`m pretty sure human kind will at some point move to other planets. And from there, we can start spreading out, increasing our chances of meeting alien life considerably.
And then there`s only one question remaining: do we actually want to meet alien life? But I`ll leave that for another time.