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Blowing up the sun?

  1. Nov 3, 2014 #1
    Let's say an alien race developed a powerful enough weapon to destroy** a star the size of our sun. How long would it take for humans on the surface of Earth or perhaps on the surface of another planet/moon in the solar system to feel the effects of this process?

    **"Destroy" is obviously ambiguous, as you might imagine several different meanings, but sadly I am not intelligent enough/educated enough to even come up with more specifics of what "destruction" of a star would entail (only one I can think of is forcing it to go supernova, but I probably sound stupid even saying that).
     
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  3. Nov 3, 2014 #2

    phinds

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    Without violating any principles of physics, the gravitational effects of such an explosion would not be felt on any object until the expanding sphere of debris goes past the object (assuming a symmetrical scattering ... a massively non-symmetrical scattering would be felt, or at least detectable, on Earth after 8 minutes)

    By the way, this forum often gets such questions (and that one specifically) so it can often be helpful to just do a forum search when you have such a question. AND ... each thread that you find will have a list of other threads at the bottom of the page that are similar in nature so a simple search can yield a lot.
     
  4. Nov 3, 2014 #3
    Ok, thank you and sorry about that.

    Edit - Did a thorough search and a lot of those threads are helpful, but none address directly and specifically what would happen to humans and in what general time period.

    I'm asking this for inspirational purposes (fiction). I was hoping to also ask the knowledgeable folks on this thread about other hypotheticals, i.e. what would happen if an alien race were somehow able to create a black hole large and nearest enough to the sun to effectively destroy the entire solar system.
     
    Last edited: Nov 3, 2014
  5. Nov 3, 2014 #4

    phinds

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    This is one of those questions that amount to asking "if the laws of physics did not apply, what would the laws of physics say about <insert any nonsense you like>" and does not, I think, have any meaningful answer.

    If by magic, and not physics, you could make the sun just go away instantaneously, without replacing it with any mass, then 8 minutes later the Earth would start moving through the solar system in a straight line (as would all the planets, at different times) and it would start getting cold. Then it would get colder. Plants would die sooner, animals would follow. Some humans would probably last for quite a while but eventually there would be no food sources.
     
  6. Nov 4, 2014 #5

    DHF

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    I think the first thing you want to figure out is why is this an important part of your plot. Why is destroying the sun needed verses simply attacking Earth directly? Our star is an ancient object that has been doing its thing for billions of years, to snuff it out instantly like you suggest would take so much energy that the story rapidly morphs into magic and not science. This in and of itself is not an issue because many soft Sci Fi tales use plot devices that require insane amounts of energy. The big problem however is: why? Why would the aliens go through all the trouble of halting a star's life like that? If the Aliens had that much energy at their disposal, they could vaporize all life on Earth instantaneously many,many,many times over. So why go through all the trouble of attacking the star? it would be like wanting to take out an ant hill by setting off a nuclear device that takes out the entire city that the ant hill resides in.

    If the main point of your story is that the aliens wanting to destroy Earth then you might want to center around a more direct route. If you really want them to attack the Sun however then I would come up with a very detailed reason for why they are focusing on the Sun. Such as perhaps they are not destroying to attack Earth but instead they are consuming it as an energy source. This still has problems of course because again, it would require unbelievable amonts of energy to stop the Sun's nuclear furnace and they would likely invest more energy consuming it then they would gain from said consumption but at least you would have a motivation that would make more sense.
     
    Last edited: Nov 4, 2014
  7. Nov 4, 2014 #6

    Ryan_m_b

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    Not really, the OP is asking if X was to happen what would the laws of physics dictate occurs next?

    Cbrons if you assume that aliens somehow make the star disappear/turn into a black hole then 8 minutes later the effects would reach Earth. The effect would be that we get cold, very fast and everything freezes and dies. Probably not instantly given how much heat is retained in the ocean but very quickly. Too quickly to do anything about.
     
  8. Nov 4, 2014 #7
    Ok thank you all.
     
  9. Nov 4, 2014 #8
    There were techno-magical reasons why I was thinking of a scenario in which they had to destroy the sun, but yes your points are very good and well taken.
     
  10. Nov 4, 2014 #9
    8 minutes is the time it would take for the light change to reach earth. if the destruction left the sun intact but snuffed out its flame we'd know it in 8 minutes. if the sun was super charged into a massive flare out the same amount of time would pass for us to see it coming/burn to a crisp. if the destruction was a more subtle type like turning down the furnace we may not see the difference until much later if no one was observing the sun for energy output at the time.. the unaided eye we might not notice the color change until long after its too late.

    a black whole would be creating vast amounts of energy wouldn't simply tossing anti-mater into the sun with the resulting cataclysmic reaction be easier for the aliens?
     
  11. Nov 16, 2014 #10
    Try calculating the Sun's gravitational self-energy some time. You will find that it is huge, larger than the mass of the Earth. So the only way to blow up the Sun with something at even vaguely approximates present-day physics is with some "conversion ray" that makes protons and neutrons decay by violating baryon number. If one converts about 10-6 - 10-5 of them, that should do it.
     
  12. Nov 18, 2014 #11
    quick question about the sun: has anyone calculated how much if any gold is produced within the sun?
     
  13. Nov 18, 2014 #12

    phinds

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    I think gold is mostly produced if/when a star goes supernova. Element production up until then is, I believe, limited to iron and below on the periodic table.

    Edit: and by the way, it's bad form to hijack a thread with an unrelated question.
     
  14. Nov 18, 2014 #13
    sorry wasn't trying to hijack it. was just curious about fusion/ fission production of heavy metals.
     
  15. Nov 18, 2014 #14

    phinds

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    Which is a perfectly good topic, but it should be in its own thread.
     
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