• Question: Will the world end ? If so, how ?

    Asked by to Laurence, Greig, Dave, Chris, Aimee on 16 Jun 2014. This question was also asked by , .
    • Photo: Greig Cowan

      Greig Cowan answered on 16 Jun 2014:

      This is a big question. Our human world could end in a couple of ways such as global nuclear war, drastic climate change or global disease. However, in all of these cases, even if there were no humans left, the Earth would probably still exist.

      However, there is one case that we know of that will destroy the Earth altogether and that will happen in about 7 billion years when the Sun runs out of it’s hydrogen fuel. In this case, it will swell in size and swallow up all of the planets in the inner solar system (including the Earth). After spending a few million years as a giant star, it will move to a new phase where it will shrink down again to a tiny size and become either a neutron star or a black hole! In either case, the Earth will have been long gone by then…

    • Photo: Aimee Hopper

      Aimee Hopper answered on 16 Jun 2014:

      Will the world end… yes. Guaranteed.
      Will it end any time soon, hopefully not.
      How will it end, hopefully when the Sun expands to a Red Giant, because the view from the Earth would be awesome until that point. Also, humans will have LONG gone from the world, so we wouldn’t need to worry 🙂

    • Photo: Dave Jones

      Dave Jones answered on 16 Jun 2014:

      Important question and the answer is yes. If it happens anytime soon it will be by some kind of man-made disaster, like a war or global warming. But, it is inevitable because the Sun will eventually start running out of fuel and when it does this is will swell up in size and swallow the Earth. Afterwards it will leave a beautiful glowing shell of gas called a planetary nebula – the kind of object I study! Go to the bottom of my profile page to see an image of one. Hopefully, by then we’ll have mastered space travel (we have about 5-6 billion years!) so we can escape to a more habitable planet to watch the beautiful nebula form.

    • Photo: Laurence Perreault Levasseur

      Laurence Perreault Levasseur answered on 17 Jun 2014:

      Yes the world will end, for sure!
      Us humans will maybe destroy ourselves in the somewhat near future, but chances are life will make it until the end of the planet (life is surprisingly tough!). Like the others said, planet Earth will be destroyed by the sun in about 5 billion years (literally ‘eaten’ by the sun). By that time, I also believe that we will have mastered the technology to colonize other planets of the solar system, and even gone to other stars!

      On an even longer timescale, however, things don’t look as good. Depending on how much dark energy there is in the Universe, in 100 billion years all galaxies beyond the local group will have disappeared beyond the cosmic light horizon (that’s because of the expansion of the Universe). That’s only about 47 galaxies! (Recall that the Universe right now is only 14 billion years old, and it’s already pretty old!! So all these numbers are INSANELY big, many times the current age of the full Universe!!!)

      In about 450 billion years, all those galaxies (in particular, our Milky Way and Andromeda) will have collided into one gigantic galaxy. Between 10^12 and 10^14 years from now (that’s one trillion to 100 trillion years), there won’t be enough hydrogen left in the galaxy to ensure normal star formation, so no new stars will be formed and remaining stars will slowly burn their fuel and die.

      In about 110 to 120 trillion years, all remaining stars will have exhausted their fuel, and the only remaining objects will be star remnants ((white dwarfs, neutron stars and black holes) and brown dwarves. Sometimes collision between those things will make new stars, but we can estimate that about 100 stars will be shining in the galaxy.

      In 1 quadrillion years, the sun will have cooled down to 5 degrees above absolute zero.

      By 10^30 years from now (there is no name for such a large number), all stars remnants will either have been ejected from the galaxy or collapsed into the central black hole of the galaxy. Between 10^36 to 10^43 years, the protons of all atoms in the Universe will (probably) decay, and the only remaining objects will be black holes. This is the Black Hole Era.

      Black holes will eventually evaporate through Hawking radiation, and by 1.7×10^106 years from now, they will have disappeared. This is the heat death of the Universe.

      By this time, things look pretty dreadful, but the next thing that will happen is great, because by 10^{10^{56}} (that is an INSANE number, by the way) random quantum fluctuations will have created a new big bang, and so everything will start all over again!!

      Ok, so last note, these estimates are based on what we currently understand of physics, and so with such big extrapolations, chances are they are completely wrong (the further in the future, the higher the chances it’s wrong!). So I wouldn’t worry too much about it, we literally have many times the age of the Universe to figure it out! (but it’s important to do research to understand those things better!!)

Comments