See another thread here for a link to an article about the oldest known star, which formed 13-14 billion years ago. It is (was) surely a gas giant like Jupiter, incapable of supporting life.

The article mentioned that our sun is believed to be a third generation star. I always thought it was a fourth or fifth generation star.

The first generation of stars had only trace amounts of elements other than hydrogen and helium. Oxygen, carbon, and other elements essential to life are cooked in the interior of stars at the end of their life cycle.

Did second generation stars have enough carbon, oxygen, et cetera for life? When did the first third generation stars form?

Does anybody have some data about when life was first possible in the universe?

How can they be sure that the sun is a third generation star?

This question has been asked of many astronomers- one recent reply was very optimistic-

'if the oldest stars formed 13.8 billion years ago life could have formed by 13 billion years ago'...

to me that is over opimistic, and I would hesitate in expecting any life older than 8-10 billion years.
Intelligent life perhaps 5-7bilion years.

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The person who said the following knows nothing about astrophysics.'if the oldest stars formed 13.8 billion years ago life could have formed by 13 billion years ago'... At the time of the first generation stars, there was hydrogen and helium and only trace amounts of other elements.

The oxygen, carbon, and other elements required for organic chemistry were cooked at the end of the life cycle of various stars and scattered by nova events. Later solar systems were built out of gas clouds containing elements cooked by previous generations of stars.

The person who said the following knows nothing about astrophysics---
snip
ha ha!
Yes, that may well be true, but he was an assistant professor of astronomy and astrophysics at an American university which shall remain nameless...
as I said, this is a ridiculously optimistic estimate, but the early formation of the planet recently discovered in Scorpius seems to lend some weight to his opinion.

A gas giant like Jupiter cannot support life, and that is the only type of planet possible for a first generation solar system.

Life on earth started about 3.5 to 3.7 billion years ago, which was close to the earliest possible time on earth. It never got started on Jupiter.

I think the astrophysicist got caught off guard and spoke without thinking. Then again, I had some classmates in my college days who managed to get a diploma without having any critical judgment facilities.

Twelve billion years ago.

Foadi: Is 12 billion years ago a wild guess? If not, how did you derive that number?

Originally posted by Dinosaur
Foadi: Is 12 billion years ago a wild guess? If not, how did you derive that number?

Large stars don't last very long. 100 million years or so. It is entirely conceivable that second generation stars were present - perhaps even common 12 billion years ago. I believe these stars would harbor enough heavy elements to create rocky planets, or at least planets similar to the Jovian moons. What do you see wrong with my stance on this?

Foadi: Your last post seems credible, but not entirely convincing.

Do you have any idea how long it takes for a solar system to form from a cloud of interstellar gas?

What percentage of stars are the massive types that burn out in less than a billion years?

How many stars must contribute to the debris from which a solar system like ours forms?

Answers to the above questions are pertient to how soon the first life could arise.

I encountered a reference that claimed that our sun was a third generation star. I always thought it was 4th or 5th generation.

I'm not saying it's likely - hell, some people believe it is unlikely that their are other life forms anywhere in the universe. I'm just saying that it is certainly possible that life could have existed 12 billion years ago, if only on a small number of planets.

I do not feel that life was likely to have existed in the first 3 billions years of the existence of the universe. Maybe 5 billion years after the start is a good estimate.

Life here on earth seems to have occurred about one billion years after the formation of the Earth. The solar system existed as a rotating disk of dense gas for some amount of time prior to the sun and planets forming. A tenuous cloud of interstellar gas took some amount of time to form the denser disk of rotating gas.

Even if huge stars go through their life cycle in millions not billions of years, it seem to me that at least 2 billion years is required for both the cooking and the gravitational condensation of enough heavy elements to provide for the formation of planets capable of sustaining life. Add in a billion or so years after formation of a planet and you get about 3 billion years.

Add in a bit of bad luck relating to the distance between a suitable planet and its star, and you add some more time. Consider that solar systems nearer the center of a galaxy, are likely to be in a hostile environment, and you need some more time for the formation of a suitable planet.

The above having been said, I am a believer in the existence of life elsewhere in the universe. I think it exists in many places. From the hsitory of life on earth, it seems that life occurs whenever suitable conditions occur.

I am pessimistic about the possibility of discovering or communicating with intelligent life else where. I think that intelligent life is orders of magnitude rarer than life, resulting in it being extremely unlikely that any is close enough in both time and space for us to find or communicate with.

Note that the dinosaurs existed and were successful for over 100 million years without developing even the suggestion of intelligence. They were wiped out by a freak cosmic accident. This indicates that evolution does not necessarily result in intelligent life forms.