Brian Cox shares the most popular theories of why haven’t we found aliens? Sharing because it allows me to expand some salient points that are not mentioned, but need to be stated for clarity.
Assumptions
1. The speed of light sets the maximum rate any species can expand, and this, along with the inverse square law, would limit detection too.
2. The average distance between stars is approximately 6 light years.
3. Space is very big. The volume of the milky way is approximately 785,398,163,397,448 light-years. That's 785 trillion light years.
So if you divide the average distance between stars into the volume, then we get 130 trillion years of travel time. Now that sets the maximum time it would take to visit every star, and of course we, or a hypothetical alien species, wouldn't need to visit every star.
I've discussed this on my other blog where I bloviated on Aliens in BattleTech, and four years ago on this blog about the Fermi Paradox. If you click the latter, I gave a ball park figure of 31 billion years to colonize the galaxy at slower than light speed.
Obviously, the assumptions will generate a different range of guesses, but that's the best we can do.
Well.
ReplyDeletehttps://en.wikipedia.org/wiki/Iosif_Shklovsky
I.S. Shklovsky: Вселенная, жизнь, разум (English: Universe, Life, Intelligence), Moscow, USSR Academy of Sciences Publisher, 1962
Revised and extended English translation of this book, coauthored with Carl Sagan, was first published in 1966, under the name Intelligent Life in the Universe, one of the latest reissues was published in 1998 by Emerson-Adams Press (ISBN 1-892803-02-X)
Stanislav Lem.
Summa technoligia.
And then... you'd be ready to discuss it... on more profound level. ;-)
Noisy anon.
Cheers for the link and recommendation.
DeleteWell... Lem is not easy thing to read.
DeleteSo.
I can propose to be a guide. Into Lem-verse. ;-)
I already tryed it in another blog, and it looks like worked out...
can give couple of links for you to decide.
Great comments from Brian Cox. Another issue is the nature of the stars themselves. It is estimated that 75% of all known stars are Red Dwarfs. We are beginning to see that exoplanets exist around some of these red dwarfs, like Trappist-1 and Gliese 581. However, solar systems surrounding red dwarfs are probably uninhabitable. First, the Goldilocks Zone around a red dwarf is so close to the star that the planets are tidally locked. This causes climatic instability inimical to life. More importantly is the wide fluctuations of energy output from red dwarfs. The have a propensity to produce dangerous solar flares. All in all, it is possible that 3/4 of all stars cannot produce planets with life.
ReplyDelete