We May Be Alone In The Milky Way After All (says Brian Cox)
Discussion
http://www.bbc.co.uk/news/science-environment-2968...
(The Human Universe, BBC 2 tonight at 9pm)
That'll cheer up the god-botherers.
(The Human Universe, BBC 2 tonight at 9pm)
That'll cheer up the god-botherers.
The thing about 'other life' being out their is not the vastness (distance wise) of the universe (that does put a damper on us casually bumping into each other popping to the shops) but its the age of the universe, its so old and we are so young that the chances are that if intelligent life has existed its long gone by now or we may be long gone by the time they exist.
The vastness of the universe both in respect to distance and in age is beyond most people comprehension, watching 'cosmos, a space time odyssey' made me feel rather small.
The vastness of the universe both in respect to distance and in age is beyond most people comprehension, watching 'cosmos, a space time odyssey' made me feel rather small.
Foliage said:
The thing about 'other life' being out their is not the vastness (distance wise) of the universe (that does put a damper on us casually bumping into each other popping to the shops) but its the age of the universe, its so old and we are so young that the chances are that if intelligent life has existed its long gone by now or we may be long gone by the time they exist.
We also have to factor in the time that an intelligent race may be detectable. For example - humans may have existed for several hundred thousand years (a blink of the eye on the scale of the age of the universe), yet we have only had the technology to both detect other intelligent life forms - and broadcast our own existence for less than 150 years (a blink of the eye in terms of human existence).
For us to detect another intelligent civilisation - they would need to not only exist at the same time as us (relatively speaking), but be sufficiently advanced to be broadcasting on frequencies that we can detect, but not sufficiently too advanced that they have superseded radio and are broadcasting in ways we cannot yet detect.
On top of all this - we only have the technology to detect broadcasts from a relatively small portion of our own galaxy - let alone the universe. There could be tens of thousands of civilisations in existence - and many more that have existed and gone extinct - but the chances of us ever knowing about this is extremely remote.
http://www.nss.org/resources/books/non_fiction/NF_...
Pretty much the conclusion of this author. A good read by the way.
Pretty much the conclusion of this author. A good read by the way.
Just work through the Drake Equation
R* = the average rate of star formation 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 planets that could support life that actually develop life at some point
fi = the fraction of planets with life that actually go on to develop intelligent life (civilizations)
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L = the length of time for which such civilizations release detectable signals into space
My numbers, with help from Wikipedia:
7 stars per year
1 all stars have planets
0.2 fraction that can support life
1 all planets that can support life go on to do so
1E-20 (intelligent life is very rare)
1 all civilizations are detectable
1E9 advanced civilizations last a long time
Why such a low value for Fi?
Just look at our world. In the 3.5 billion years we have had life the first 3 billion were all taken up getting as far as jelly fish. In the time since then life has filled the Earth and then been smashed back again and again, more species have gone than currently live even though we now have a lot of species. How many species can use tools? A dozen? How many of those got as far as the wheel? Just us. Now consider how few people in any generation actually make a big contribution to technology. Hardly any. Even in a century there aren't many compared to the vast numbers that change nothing. Just a few percentage points less in brain power and the wheel might have been as good as it ever got for us.
The simple truth is that any kind of technological intelligence is very unlikely, evolution is more likely to come up with just about anything else and has done so for millions and millions of years.
So despite the high values above, including my very high life for civilizations, that 1E-20 just hammers the result.
We are freaks. The universe is full of life but its nearly all stuff on a par with jelly fish, worms and ants.
R* = the average rate of star formation 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 planets that could support life that actually develop life at some point
fi = the fraction of planets with life that actually go on to develop intelligent life (civilizations)
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L = the length of time for which such civilizations release detectable signals into space
My numbers, with help from Wikipedia:
7 stars per year
1 all stars have planets
0.2 fraction that can support life
1 all planets that can support life go on to do so
1E-20 (intelligent life is very rare)
1 all civilizations are detectable
1E9 advanced civilizations last a long time
Why such a low value for Fi?
Just look at our world. In the 3.5 billion years we have had life the first 3 billion were all taken up getting as far as jelly fish. In the time since then life has filled the Earth and then been smashed back again and again, more species have gone than currently live even though we now have a lot of species. How many species can use tools? A dozen? How many of those got as far as the wheel? Just us. Now consider how few people in any generation actually make a big contribution to technology. Hardly any. Even in a century there aren't many compared to the vast numbers that change nothing. Just a few percentage points less in brain power and the wheel might have been as good as it ever got for us.
The simple truth is that any kind of technological intelligence is very unlikely, evolution is more likely to come up with just about anything else and has done so for millions and millions of years.
So despite the high values above, including my very high life for civilizations, that 1E-20 just hammers the result.
We are freaks. The universe is full of life but its nearly all stuff on a par with jelly fish, worms and ants.
Off topic but Brian Cox on keyboards in a previous life:-
https://www.youtube.com/watch?v=DMEGgYNNrCw
https://www.youtube.com/watch?v=DMEGgYNNrCw
I thought it was the best one of the series so far...
The fateful encounter concept was interesting. The use of the 2 day flowering orchid to illustrate the civilisation window "problem" was a nice way to show it.
T think the actual conclusion was not that we may be all alone but rather than we may be the only example of complex life due to the fateful encounter probability being so very low. So lots of life out there but likely of the stromatlite type as opposed to the dolphin type.
I know it's fashionable to dismiss him and his brand of faraway, misty eyed staring, T.V. science but personally I find his programs interesting and any one who includes quotes from Carl Sagan can't be all bad surely.
If you really want to worry the god botherers you could mention that we may be alone and we may be the first and that in x many millions of years we will have "seeded" the galaxy/universe and that as such we can consider ourselves as the "creator" - we are all god
The fateful encounter concept was interesting. The use of the 2 day flowering orchid to illustrate the civilisation window "problem" was a nice way to show it.
T think the actual conclusion was not that we may be all alone but rather than we may be the only example of complex life due to the fateful encounter probability being so very low. So lots of life out there but likely of the stromatlite type as opposed to the dolphin type.
I know it's fashionable to dismiss him and his brand of faraway, misty eyed staring, T.V. science but personally I find his programs interesting and any one who includes quotes from Carl Sagan can't be all bad surely.
If you really want to worry the god botherers you could mention that we may be alone and we may be the first and that in x many millions of years we will have "seeded" the galaxy/universe and that as such we can consider ourselves as the "creator" - we are all god
jbudgie said:
The Milky Way is only our own galaxy--if there are life forms in each galaxy then there will be billions of civilizations in the universe.
I thought that this deserved a mention at the end of the programme. We'll probably never contact life in another galaxy, but it was worth at least pointing out the number of galaxies out there, perhaps illustrated with the Hubble Deep Field:
And that's a 24-millionth of the sky....
Edited by RobM77 on Wednesday 22 October 11:00
I think Douglas Adams said it best, we're not just alone, we're not even here.
It is known that there are an infinite number of worlds, simply because there is an infinite amount of space for them to be in. However, not every one of them is inhabited. Therefore, there must be a finite number of inhabited worlds. And finite number divided by infinity is as near to nothing as makes no odds, so the average population of all the planets in the Universe can be said to be zero. From this it follows that the population of the whole Universe is also zero, and that any person you may meet from time to time are merely the products of a deranged imagination.
No-one linked to the Deep Field Video?
http://www.youtube.com/watch?v=mcBV-cXVWFw
Awe inspiring and humbling.
http://www.youtube.com/watch?v=mcBV-cXVWFw
Awe inspiring and humbling.
cymtriks said:
Why such a low value for Fi?
Cox covered that; it's all down to the very lucky formation of eukaryotic cells with mitochondria. He said it's considerded so unlikely it may only have happened the once, and that some kind of energy-producing symbiosis is essential for multicellular/complex organisms.cymtriks said:
My numbers, with help from Wikipedia:
7 stars per year
1 all stars have planets
0.2 fraction that can support life
1 all planets that can support life go on to do so
1E-20 (intelligent life is very rare)
1 all civilizations are detectable
1E9 advanced civilizations last a long time
Not sure about some of your figures - but especially the last one. What units is this in (i'm presuming years). 7 stars per year
1 all stars have planets
0.2 fraction that can support life
1 all planets that can support life go on to do so
1E-20 (intelligent life is very rare)
1 all civilizations are detectable
1E9 advanced civilizations last a long time
If so - do we really have the confidence to say that a technologically advanced civilisation (i.e. advanced enough to be detectable) will last for 1 billion years on average. Our own civilisation has only been in such a state for about 150 years.
Put that timescale into context. 1 Billion years ago - life on earth was only just at the "complex multicellular" level (i.e. algae, protozoa).
Looking at our rocky accent to the pinnacle of the food chain, as long as we had an advantage of an AK47 (we could not take on a lion without help), I wonder if we are freaks in evolution. Learning to chuck spears at out dinner has no check from evolution. Scary in a way, where is the check?
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