Drake equation

[Liz]

A nice, stimulating start to the day :) ..... Carl Sagan is/was a great presenter, and I enjoyed this.

http://www.freesciencelectures.com/video/carl-sagan-explains-the-drake-equation/

[xelasnave]

Thanks Liz...
Some folk grab at this equation almost as if it offers proof I feel ...it is great to speculate but we need to remember it is just that.
The big numbers we have to work with means the smallest percentages placed will give us opportunity...
makes you wonder however...

alex

[jungle11]

It's a well thought out assumption, but we have so little knowledge it's bound to be updated in future history i think.

We don't know yet if life could arise from alternative processes (ie other than amino acids) Perhaps many different worlds are capable of supporting one sort or another.

Also, if one of the rare advanced civilizations spread out into the galaxy, taking their terrestrial ecosystems with them, things could be vastly different.

Of course if the second proposition is true, then Fermi's Paradox comes into play as well....

It's a cool subject...I think life is far and away the most incredible process we know of in the universe.:thumbsup:

[Paddy]

I remember Carl Sagan going through this on Cosmos in the early 80's and being struck by the dramatic effect of including, as he so eloquently put it, the trap of the combination of technology and passions leading to the early end of civilizations.

I also recall an astronomer on the radio last year when asked whether there was intelligent life on other planets saying rather wisely that we should try to find intelligent life on Earth as a starting point.

Thanks for the posting Liz - and love his 70's hairstyle & clothes!

[Enchilada]

The only Drake equation I know is
....don't trust anyone from Spain. :lol:

[Liz]

http://www.freesciencelectures.com/video/carl-sagan-on-planet-venus/

check out a very cool, young Carl in this short video.

wow, there is some very interesting info on this site

http://www.freesciencelectures.com/video/the-search-for-extraterrestrial-intelligence-by-carl-sagan/

[Paddy]

Young! He looks like he's about 12!

[Liz]

I know, made me laugh :lol:

[renormalised]

I'm back!!!!!....been away for quite some time.

About the Drake Equ' and the Fermi Paradox...Liz's sig sums it all up. The reason why we (supposedly) don't see all the little critters from upstairs is simple. Why would you want to visit the inmates at the loony bin??!!:P:D

[g__day]

I've read about the number of factors (about 31 key ones) that have to align for a plamet to support life - this was the the Ne factor in this famous equation. I think the best estimate for any planet in the Universe to have conditions suitable to support life are extremely low - roughly less than one in google chance for any life - let alone advanced life. You really have to fluke many factors that include:

1. Age of Sun
2. Size and mass of Sun
3. Distance of Sun from galactic core (about 2/3's out is optimal)
4. Size of planet
5. Mass of planet (no more or less than 10% Earth's weight)
6. Distance of planet from Sun (You need the right temperatures to support life)
7. Presence of Moon
8. Size of Moon and distance from planet
9. Planet requires and Iron core (you need a magnetic shield to eliminate radition that would otherwise sterilise all life)
10. Planet requires abundant water in liquid form (to mix chemicals, act as a heat buffer and resevior etc)
11. Planet requires plate tectonics
12. Planet requires silica balance
13. Planet requires one or more gas giants further out in solar system (to vaccuum up killer asteroids during solar system creation and the next few billion years)
14. Presence of Ozone (need to deflect ultra violet radiation)

And so on for another twenty factors - any one of which being set wrong means the raw building blocks of life aren't likely to form or be preserved.

Basically you're cross multiplying 31 factors that might have a one in a hundred to one in a billion. Say on average a one in then thousand chance - then that is 10 ^ 31 * 4 or 10 ^ 120.

We guesstimate there is around 10 ^ 26 planets in our Hubble sphere.

[renormalised]

The problem with the Drake Equation is that it is ultimately based on the only example of life that we know of, and even in this instance they've found life in places and situations which have and are still completely confounding the scientists. It's based completely on suppositions predicated on mostly guesstimates about conditions to which they really know very little to nothing about. Like all mathematical equations you get out of it what you put into it....basically it's a fanciful thought experiment. Something interesting to wile away the time and generate a debate of "maybes". But in the end it's basically meaningless, simply because there's no real answer to the equation.

You can either get N=0, so we don't exist, or you get N=10's of billions (at least within the Galaxy), and we're upto our armpits in "martians":eyepop::P:D