<p>Not that easy way. Only stars heavy enough will undergo a <a href="http://en.wikipedia.org/wiki/Supernova" rel="nofollow">supernova</a> explosion. The majority of stars is too light. The lifetime of a star is mostly determined by its <a href="http://en.wikipedia.org/wiki/Stellar_mass" rel="nofollow">mass</a>. In some cases (supernova type Ia) a companion star provides mass to white dwarf, which originally has been too light to explode as a supernova.</p>

<p>Hence your technique can only work, if it is applied to stars of a certain mass and composition separately, and then summed or integrated up over all these restricted classes of stars. All together you'll get results for stars which eventually will end up as supernova, i.e. the heavy ones with more than about 8 solar masses.</p>

<p>... And in the meanwhile <a href="http://en.wikipedia.org/wiki/Star_formation" rel="nofollow">new stars will form</a>.</p>

CC BY-SA 3.0
2014-03-02T18:54:16.190Z
and binary stars count as well. Where 1 is a red giant and 1 is a white dwarf. Would ternary stars which are 3 stars orbiting around themselves have a supernova type 1a? Yes new stars will form but you know there might be a point in time very far in which there are no more stars and stars have to form from the atoms once again, like a second big bang.
Caters
CC BY-SA 3.0
2014-03-02T19:52:16.240Z
@caters In the long run fuel for star formation will run short, and the longest-living stars will cool down, yes. If a ternary contains a white dwarf and a giant, close enough to each other, a type 1a supernova can be the result.
Gerald
CC BY-SA 3.0
2014-03-02T20:28:51.943Z
but why? I mean in all these supernovas you have not only heavier metals forming like gold but also the smaller atoms like hydrogen released so isn't there like an equilibrium between hydrogen used and hydrogen released?
Caters
CC BY-SA 3.0
2014-03-02T21:34:18.877Z
@caters No, part of the hydrogen is fused to heavier elements, releasing energy. Fusing or splitting iron nuclei needs energy. Most of the hydrogen released by supernovae has never been fused, but has been in the outer shell of the collapsing star. There is no equilibrium, because there is no source of energy needed to split heavier nuclei to hydrogen.
Gerald
CC BY-SA 3.0
2014-03-02T21:44:54.793Z
yes but there are regions in the star where a certain element never fuses. That is what is released to make new stars. Why wouldn't the energy released from the supernova form heavier elements and split atoms into alpha particles and smaller atoms and sort of forcing alpha decay?
Caters
CC BY-SA 3.0
2014-03-02T22:09:58.693Z
@caters This may occur to some degree, but most of the fused hydrogen is lost due to the formation of stable heavier elements, like carbon, oxygen, silicon or iron. Most of the fusion energy released during the lifetime of the star has been radiated away, and isn't available any more to split up heavy nuclei into hydrogen. Some of the iron is fused to heavier elements like lead or uranium, consuming part of the energy released by the collapse of the core.
Gerald
CC BY-SA 3.0
2014-04-25T19:16:38.400Z
there is a reccurence time for our universe where a second big bang will happen, a second earth like ours will form, life will form again, people recording videos will record videos again, and lots of other things. That is after all the stars die out as white dwarfs or supernovae or black holes and after all the black holes die out from their radiation.
Caters
CC BY-SA 3.0
2014-04-26T03:21:23.017Z
@caters It doesn't look like, based on the current main stream model, but we can't tell for sure.
Gerald
CC BY-SA 3.0
2014-04-26T03:26:26.700Z
A numberphile video on youtube told me about it. You should check it out.
Caters
CC BY-SA 3.0
2014-04-26T03:46:22.330Z
@caters (http://www.youtube.com/watch?v=1GCf29FPM4k) funny, thanks! But I'm sorry, not conclusive. First, it's assumed, that the universe can obtain only a finite set of states; that's not proven. Second, assumed there is only a finite set of possible states, they may repeat periodically at some late state of the universe, without warranty that it restarts from the beginning.
Gerald
CC BY-SA 3.0
2014-04-26T03:56:18.900Z
yeah but still all the things that have happened in the universe will happen again at the recurrence time including the big bang and formation of life.
Caters
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2014-10-10T01:33:01.177Z
@caters No, we have no reason to think this will happen.
HDE 226868
CC BY-SA 3.0
2014-10-10T03:34:18.863Z
There has to be a finite number of quantum states. Nothing in real life can reach infinity. Not even quantum states of our universe(I say our universe because we might be in a multiverse where matter is exchanged via black holes and white holes so that we are at equilibrium in a multiverse).
Caters
CC BY-SA 3.0
2014-10-10T03:36:10.573Z
And even if it weren't finite, if we are in a multiverse, a second big bang that leads to similar things as the first one did would still be a possibility.
Caters
CC BY-SA 3.0
2014-03-02T14:10:47.500Z
2014-03-02T14:10:47.500Z
Gerald
<p>If we would take the average number of supernovae per year and multiply that by the number of stars, could we figure out how many years it will be before all stars are gone?</p>

<star><supernova>
Average rate of supernova x number of stars
Caters
# Average rate of supernova x number of stars

(Asked by: username_0 on 2014-03-02)

If we would take the average number of supernovae per year and multiply that by the number of stars, could we figure out how many years it will be before all stars are gone?

**Tags:** star, supernova

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## 1 answers

### Answer by username_1 on 2014-03-02. Score: 4

Not that easy way. Only stars heavy enough will undergo a [supernova](http://en.wikipedia.org/wiki/Supernova) explosion. The majority of stars is too light. The lifetime of a star is mostly determined by its [mass](http://en.wikipedia.org/wiki/Stellar_mass). In some cases (supernova type Ia) a companion star provides mass to white dwarf, which originally has been too light to explode as a supernova.

Hence your technique can only work, if it is applied to stars of a certain mass and composition separately, and then summed or integrated up over all these restricted classes of stars. All together you'll get results for stars which eventually will end up as supernova, i.e. the heavy ones with more than about 8 solar masses.

... And in the meanwhile [new stars will form](http://en.wikipedia.org/wiki/Star_formation).

> **Comments:**
> **username_0**: and binary stars count as well. Where 1 is a red giant and 1 is a white dwarf. Would ternary stars which are 3 stars orbiting around themselves have a supernova type 1a? Yes new stars will form but you know there might be a point in time very far in which there are no more stars and stars have to form from the atoms once again, like a second big bang.  
> **username_1**: @caters In the long run fuel for star formation will run short, and the longest-living stars will cool down, yes. If a ternary contains a white dwarf and a giant, close enough to each other, a type 1a supernova can be the result.  
> **username_0**: but why? I mean in all these supernovas you have not only heavier metals forming like gold but also the smaller atoms like hydrogen released so isn't there like an equilibrium between hydrogen used and hydrogen released?  
> **username_1**: @caters No, part of the hydrogen is fused to heavier elements, releasing energy. Fusing or splitting iron nuclei needs energy. Most of the hydrogen released by supernovae has never been fused, but has been in the outer shell of the collapsing star. There is no equilibrium, because there is no source of energy needed to split heavier nuclei to hydrogen.  
> **username_0**: yes but there are regions in the star where a certain element never fuses. That is what is released to make new stars. Why wouldn't the energy released from the supernova form heavier elements and split atoms into alpha particles and smaller atoms and sort of forcing alpha decay?  
> **username_1**: @caters This may occur to some degree, but most of the fused hydrogen is lost due to the formation of stable heavier elements, like carbon, oxygen, silicon or iron. Most of the fusion energy released during the lifetime of the star has been radiated away, and isn't available any more to split up heavy nuclei into hydrogen. Some of the iron is fused to heavier elements like lead or uranium, consuming part of the energy released by the collapse of the core.  
> **username_0**: there is a reccurence time for our universe where a second big bang will happen, a second earth like ours will form, life will form again, people recording videos will record videos again, and lots of other things. That is after all the stars die out as white dwarfs or supernovae or black holes and after all the black holes die out from their radiation.  
> **username_1**: @caters It doesn't look like, based on the current main stream model, but we can't tell for sure.  
> **username_0**: A numberphile video on youtube told me about it. You should check it out.  
> **username_1**: @caters (http://www.youtube.com/watch?v=1GCf29FPM4k) funny, thanks! But I'm sorry, not conclusive. First, it's assumed, that the universe can obtain only a finite set of states; that's not proven. Second, assumed there is only a finite set of possible states, they may repeat periodically at some late state of the universe, without warranty that it restarts from the beginning.  
> **username_0**: yeah but still all the things that have happened in the universe will happen again at the recurrence time including the big bang and formation of life.  
> **username_2**: @caters No, we have no reason to think this will happen.  
> **username_0**: There has to be a finite number of quantum states. Nothing in real life can reach infinity. Not even quantum states of our universe(I say our universe because we might be in a multiverse where matter is exchanged via black holes and white holes so that we are at equilibrium in a multiverse).  
> **username_0**: And even if it weren't finite, if we are in a multiverse, a second big bang that leads to similar things as the first one did would still be a possibility.  

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