Our place in time in the universe

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RedClaws

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Hello all,

First of all, I apologize if this has been posted already. I couldn't find anything with the search function.
I also apologize for my English, it is not my first language.

Yesterday I found myself contemplating our place in time in the universe and started to look some things up and I'd appreciate it if you would voice your opinion or point out errors. References to my finds are at the bottom of the post.

The current universe is 13.7 billion years old, our sun is around 4.5 billion years old. To me it seems like the universe, in relation, seems very young.

The first stars, classified as Population III stars with extremely low metallicity, were born only 200 million years after the big bang. These stars have short lifespans of less than a million years and produce the metals needed to form Population II stars. [1]

The oldest known population II star HE0107-5240 is estimated to be 12 billion years old. So population II stars began to form around 1 billion years after the big bang and they, in turn, produced the metals for the Population I stars. [2]

Around 3 billion years after the big bang, there were enough metals in the universe to start producing the first Population I stars and with them, the first planets (since a high metallicity is needed to produce planets).
These stars last for quite some time, our own sun for example has a lifespan of 10 billion years.

To me, this seems like our sun and our planets are one of the first "generations" of stars and planets.

If we look into the future of the universe we estimate that star production will continue until 10 trillion years after the big bang and that metallicity will increase even further. [3[

So that means that only 0,0137% of the time where the universe can create stars and planets has passed. And by the time our sun grows into a red giant and life in the inner solar system becomes impossible only 0,0147% of star and planet producing time has passed.

Does this surprise you or change your perspective on our place in time? It did for me if this is accurate.
How do you think metallicity will evolve with time? Will it increase slowly or simply reach a point where it will become stable? How will an extreme metallicity effect star creation?


Sidenote: Ofcourse the amount of metals are different in different regions of the universe but let's focus on our own little corner of space.


References:
1: http://mynasa1.nasa.gov/vision/universe/watchtheskies/universe_objects.html
2: Christlieb, N., Bessell, M. S., Gustafsson, B., Korn, A., Barklem, P. S., Karisson T., Mizuno-Wiedner M., and Rossi, S. "A stellar relic from the early Milky Way," Nature, 419, 904-906 (2002).
3: http://rmp.aps.org/abstract/RMP/v69/i2/p337_1
 
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neilsox

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True a star may be born between 9 trillion and ten trillion years, but my guess is star birth will be rare long before that. Why rare? 1 the Universe is expanding at an accelerating rate, so galactic groups are getting farther apart 2 Galactic groups will rarely collide in our future, reducing one of the stimulants to star birth 3 With each star birth, some mass is ejected from the galactic group. Ejected means traveling fast enough to leave eventually = the delay may be a trillion years, typically 4 the photons and neutrinos that leave galactic groups also represent a mass loss for the galactic groups and a gain for the inter galactic space. 5 Some of the star material is recycled shortly before a star becomes a compact star Almost none is recycled from compact stars which are increasing in number rapidly. 6 large nebula of gas and particles are becoming rare, so there will be few places a star can be born in a trillion years, perhaps sooner. I'm guessing, so tell me where this might be wrong. Neil
 
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origin

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Those are good points, I to have thought about our timing in the universe. However to me it is simply a reflection of our human nature to be idiocentric. The age of the universe seems special because we exist. No matter when it was that we existed, we would tend to think it is a special time. We tend to view history the same way. This is a unique period in history is often heard but the truth is it is no more unique than any other time in history.
 
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