Pastabake

Latest adventure into the universe: the unlikelihood of life in the 20 nearest star systems

Take a read if you fancy, I liked writing it so you never know it might be alright to read

Well it’s quite depressing, just to warn you

Yes I’m a nerd 

In the twenty nearest star systems including our own there are 29 different stars. Life on earth has evolved due to a particular set of conditions and as this is the only occurrence of life we know of, this is the basis of the chain of reasoning that leads me to believe that it is highly unlikely that any of the other 28 nearby stars are host to a planet bearing intelligent life. Firstly there needs to be a suitable sun. The sun needs to be on the main sequence, so it is stable with constant light. Stability is important because solar eruptions could harm the inhabitants of the planet. It should also be the right spectral type in order to have a long life so that life on the planet has time to arise and evolve (on earth this took 4.6 billion years), and the right amount of light, so that plants have enough light to photosynthesise. The star needs to be old enough to have a planet which has had long enough to developed intelligent life and the star also needs to be metal rich so that rocky planets that are able to support life as we know it are formed from the heavy element matter surrounding it.  After all 28 nearby stars have been scrutinised by these conditions only three stars remain; Alpha Centauri A and B and Tau Ceti. Tau Ceti’s metallicity is low compared to that of the sun so the probability of rocky planets forming around it is reduced. And having planets at all would be difficult for Alpha Centauri A and B as the stars form a double with an eccentric orbit around each other which could potentially upset the orbit of any planets on either star.

Even after this a planet is still needed. The conditions for this are almost as restrictive as those for the planet’s sun, such as; the planet must be the right distance to the sun to be warm and have liquid water which is a very thin band width in the solar system, and it must also be massive enough to retain it’s atmosphere. Even if conditions were perfect and an earth-like planet was orbiting a sun-like star at a good distance, intelligent or even primitive life may not form. As scientists do not know the exact way life started on earth, it is impossible to be sure of exactly what it is that could start it off on other planets. Primitive life may occur but it may not evolve into more complex beings. And intelligent life could easily be killed off by comets or dramatic climate changes like ice ages or even stronger, faster animals. Human’s intelligence is the key to their success, as speed, strength, thick skin and vicious teeth or claws are assets we do not possess. This may be less important on other planets and so life may evolve without any being in possession of particularly great intelligence. All of this leads me to believe that within the twenty nearest star systems, intelligent life is extremely unlikely.