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How Will the Universe End? Scientists Say They May Have an Answer (sciencemag.org) 153

sciencehabit shares a report from Science Magazine: In the unimaginably far future, cold stellar remnants known as black dwarfs will begin to explode in a spectacular series of supernovae, providing the final fireworks of all time. That's the conclusion of a new study, which posits that the universe will experience one last hurrah before everything goes dark forever. The dramatic detonations will begin to occur about 10^1100 years from now, a number the human brain can scarcely comprehend. The already unfathomable number 10^100 is known as a googol, so 10^1100 would be a googol googol googol googol googol googol googol googol googol googol googol years. The explosions would continue until 10^32000 years from now, which would require most of a magazine page to represent in a similar fashion.

A time traveler hoping to witness this last cosmic display would be disappointed. By the start of this era, the mysterious substance acting in opposition to gravity called dark energy will have driven everything in the universe apart so much that each individual black dwarf would be surrounded by vast darkness: The supernovae would even be unobservable to each another.
The study has been published in the journal Monthly Notices of the Royal Astronomical Society.
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How Will the Universe End? Scientists Say They May Have an Answer

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  • by grep -v '.*' * ( 780312 ) on Wednesday August 12, 2020 @02:10AM (#60392733)
    Sounds great -- I can hardly wait to see it. (Restaurant at the End of the Universe joke here.) Hopefully it ends "over there first" so that I get a chance to move to a new neighborhood.

    (Asimov: The Final Question [princeton.edu]
    • by NoNonAlphaCharsHere ( 2201864 ) on Wednesday August 12, 2020 @03:19AM (#60392811)
      It's "The Last Question", not "The Final Question". Greatest sci-fi short story ever written; possibly the best short story (period) ever written. Asimov always said it was his favorite.
    • by Mr. Dollar Ton ( 5495648 ) on Wednesday August 12, 2020 @03:20AM (#60392813)

      Don't get your hopes high.

      This is just your normal Hawkingism - make a dramatic "prediction" about something that cannot be tested, ever, and have fun.

      It ain't no science, it is just story-telling.

      • Re: (Score:3, Interesting)

        Except this new prediction and the Hawking heat-death prediction are mutually incompatible.

        A black hole loses mass through Hawking radiation, but a black dwarf would lose mass from radiation too, and far, far faster.

        The lifetime of a black hole increases as the cube of the mass. The smallest black hole is about 3.3 solar masses. The largest black dwarf has a mass of about 1.4 solar masses (any larger and it would be a neutron star or BH). So the black dwarf is going to evaporate an order of magnitude fas

        • by rpresser ( 610529 ) <rpresser&gmail,com> on Wednesday August 12, 2020 @08:41AM (#60393323)

          Black dwarfs do not have an event horizon, so they do not emit Hawking radiation, and do not evaporate from it (or from any other reason). Like other ordinary matter, they do emit thermal radiation, which cools them down.

          • do not evaporate from it (or from any other reason).

            Yes they do. They evaporate far faster than a BH.

            A BH of 3.3 solar masses will emit mass at a rate of 8e-30 W. A paperweight sitting on your desk will emit a quadrillion times as much.

            Like other ordinary matter, they do emit thermal radiation

            Emitting "thermal radiation" and emitting mass are the SAME THING. E=mc^2.

            • LOL, no.

              You're confusing energy equivalence with the ability to emit a particular form of energy. You cannot just say "objects of type XXX emit YYY because E=mc^2", not without telling us what decay process of the particles of which XXX is composed generates the YYY.

              White dwarfs are basically hot soup of stable particles, mostly protons, electrons and some neutrons, which cools off slowly by electromagnetic radiation. Black dwarfs are cooled down white dwarfs - they have no energy to emit, so they don't.

              The

              • by piojo ( 995934 )

                The article describes slow fusion (and antimatter reactions) which implies they will lose mass and emit heat. And to speak to the GP's comment, when a system gains any type of energy, it gains mass. And vice versa. So since he was assuming significant radiation (probably having read the article), one wouldn't question that mass is lost--however if you assume black body radiation is the only thing happening (you wrote that they are stable), this radiation would asymptotically approach zero with the temperatu

                • The article is completely irrelevant to what's discussed in the thread (and completely irrelevant anyway, as it is an empty speculation). If a system gains energy, it gains mass equivalent, not mass, and ditto for the opposite. The form of the energy/mass/whatever is what is important here, and there is no form in a black dwarf in thermodynamic equilibrium with its environment that can produce "evaporation" via EM emissions.

            • Fine, let's run some numbers. This black hole evaporation time calculator [easycalculation.com] computes that a black hole of mass 100kg will evaporate in 1.271937592821698e-19 seconds. I know several people about 100kg in weight, and none of them have evaporated yet. Arguments that they take in mass continuously through eating and breathing are irrelevant because they don't do it *that* fast.

              Clearly something is wrong here. I submit that what is wrong is your assertion that black hole evaporation times can be applied to things

        • by Bengie ( 1121981 )
          What did I miss? The black dwarf doesn't evaporate, it's goes supernova. The black dwarf is just a white dwarf that has cooled off, but due to the nature of quantum, fusion will still occur very very very slowly. Some of these fusion pathways will create positrons which will destroy electrons in the star, eventually leading to the collapse of the star resulting in a super nova. The rate this happens is driven by the rate of fusion, not some "evaporation". Or what did I miss?
      • by jbengt ( 874751 )
        TFA agrees:

        Still, “I think it’s important to stress that any investigations of the far future are necessarily tongue in cheek,” Laughlin says. “Our view of the extremely distant future is a reflection of our current understanding, and that view will change from one year to the next.”

      • Well, it can be tested. You just have to be patient.

    • Not with a bang, but a whimper.
    • Actually that depends on the nature of Dark Energy. Even after the last of these supernovae space will remain but it is possible that if Dark Energy keeps building then at some point the causally connected distance could shrink to below the planck length at which point the guess is that there may be a "big rip" since space-time itself will come apart.
  • by Evtim ( 1022085 )

    Both a bang and a whimper then?

    Gosh, this reeks of duality so much that I can't decide how to feel about such an end.

    Anyway, the number of years makes the whole thing rather......is there an emoticon for 'no words can represent this concept'? I need one now.

    • by rtb61 ( 674572 )

      Now for a touch of reality versus the known universe as far as mud monkeys are concerned. How will the universe end, it will end when it no longer has the will to exist. When the universe ceases it's quest for the future, through the expressed living will of the universe, us and every other living part of the universe, so the universe will end. The universe relatively speaking is infinite because time is life and life is time, it is all just physics, including the weird bits in quantum space and in null spa

    • by ceoyoyo ( 59147 )

      More like isolated screams in the night.

  • Googolplex, now that's a number!

    • Just where I was going...it's been a long time since I stacked exponents, but I think this is maybe 11 googleplexes?

      https://en.wikipedia.org/wiki/Googolplex

      Maybe some math major out there can keep me honest.

  • Nah (Score:4, Funny)

    by Viol8 ( 599362 ) on Wednesday August 12, 2020 @02:34AM (#60392761) Homepage

    Once its all gone dark and boring God will simply come along , bring up the console shell /big/bang and type "shutdown -r now"

  • by petes_PoV ( 912422 ) on Wednesday August 12, 2020 @02:38AM (#60392767)

    cold stellar remnants known as black dwarfs will begin to explode in a spectacular series of supernovae, providing the final fireworks of all time.

    So will there be a restaurant (at the end of the universe) where we can all watch this from?

    I'll deposit my 1 in a bank account now. The accrued interest should pay for the meal when the time comes.

  • by Rei ( 128717 ) on Wednesday August 12, 2020 @02:55AM (#60392785) Homepage

    A: Dark energy is going to explode black dwarfs in 10^1100 years.
    Q: Okay. And what exactly is Dark Energy again?
    A: No bloody idea.
    Q: But you're confident in describing how it will behave 10^1100 years from now?
    A: Yep.
    Q: Okay then.

    • by TonyJohn ( 69266 )
      That was my thought too, though to be fair the original article quotes a scientist:

      "it’s important to stress that any investigations of the far future are necessarily tongue in cheek"

      In other words, the confidence comes from the summarising and resummarising by journalists rather than the original paper.

    • by wiredog ( 43288 ) on Wednesday August 12, 2020 @06:05AM (#60393025) Journal

      Dark energy has nothing to do with the explosions. It's electron tunneling creating positrons that weaken electron pressure, leading to collapse of the stars and the final supernovae.

      Dark energy just means that the stars will all be out of sight of each other.

    • Any model which depends on an unknown for 90% of the model is just wishful thinking.
    • by jellomizer ( 103300 ) on Wednesday August 12, 2020 @07:43AM (#60393199)

      Tens of thousand years ago, people were able to predict the seasons, when the sun will rise and fall every day, to a good deal of accuracy.
      They had no idea why this happened or what really caused the patterns. However the reason why Astrology was such a popular field of study, as it did predict the future to an extent. Knowing when to plant crops, Planning to have resources available during brighter full moon night to collect crops. The moon cycles roughly the same as a humans female menstrual cycles, so advice when to get pregnant wasn't too bad of a prediction as well.
      Astrology isn't science, as the Cause and effect are not correctly mapped, and as time went on and better time tracking has appeared, the Astrologists tried to "Expand Their Craft" to make more predictions based on odder and odder patterns, to a point where it is garbage today.

      We have studied the effect of Dark Energy and Dark Matter. We do not fully understand it, but we can see how it affects the Universe. So we can extrapolate what can happen in the future.

    • by ceoyoyo ( 59147 )

      It doesn't have anything to do with dark energy. The prediction is that the black dwarfs will *very* slowly turn themselves into balls of iron 56 due to tunnelling nuclear fusion reactions. Since the neutron ratio is higher, there are fewer electrons around to provide electron degeneracy pressure, so if the star is heavy enough it will at some point exceed the Chandrasekhar limit and collapse into a neutron star.

      It's all pretty standard nuclear physics, just extrapolated over a very long time.

    • by kbahey ( 102895 )

      A: Dark energy is going to explode black dwarfs in 10^1100 years.
      Q: Okay. And what exactly is Dark Energy again?
      A: No bloody idea.
      Q: But you're confident in describing how it will behave 10^1100 years from now?
      A: Yep.
      Q: Okay then.

      "No Bloody Idea" is inaccurate ...

      The same applies to dark matter, and ... gravity!

      We don't know the particles pertaining to any of the three

      However, we can measure each of them and do useful things.

      For example, calculate the variable g on earth which is 9.807 m/s2, design rockets

      • by Rei ( 128717 )

        Extrapolation far beyond the end of a graph of a poorly defined process rarely works out well. [xkcd.com]

        For example, calculate the variable g on earth which is 9.807 m/s2

        What a perfect example! Because if you measured 9,807m/s2 as the force of gravity, and assumed it applied everywhere else too, your rockets would rapidly go offcourse. :)

        • by Rei ( 128717 )

          Even better xkcd ;) [google.com]

        • by kbahey ( 102895 )

          What a perfect example! Because if you measured 9,807m/s2 as the force of gravity, and assumed it applied everywhere else too, your rockets would rapidly go offcourse. :)

          Well, the point is that we have equations for gravity that work on Earth, the Moon and Mars.
          And based on those equations, we can launch rockets and land vehicles successfully.
          All that without gravity even being in the standard model of particle physics, and no theory of quantum gravity.
          The same goes for dark matter and dark energy: no parti

  • by backslashdot ( 95548 ) on Wednesday August 12, 2020 @03:34AM (#60392825)

    Honestly I dont think it is gonna end. I think we are stuck with it. Nice going God.

  • Honestly I dont think it is gonna end. I think we are stuck with it. Nice going God.

  • Honestly I dont think it is gonna end. I think we are stuck with it. Nice going God.

  • by De_Boswachter ( 905895 ) on Wednesday August 12, 2020 @03:58AM (#60392859) Homepage
  • Anyone who's ever played Lemmings can understand why this hypothesis could be deeply satisfying, if true.

  • by vakuona ( 788200 ) on Wednesday August 12, 2020 @04:06AM (#60392873)

    If the explosions start at 10^1100 and end at 10^32000, then can we really say this is how the universe ends. A bit like saying a 100m Olympics race is ending from about 1 nanometer in.

    • Yeah but if we can correctly model the exact abilities of all participants and have a significant confidence that all other externalities have been considered then we would be able to predict the ending of the Olympic 100m without problem.

      That is science.

      • by vakuona ( 788200 )

        I am not disputing that you may be able to predict from such a short observation period, but what they are essentially saying is that for nearly all of the life of the universe (about 99.999....999% (i.e. 30,000 9s), dwarf stars will be exploding and providing an awesome light show. That doesn't much feel like an ending but rather than pretty much from the beginning of the universe (in cosmic time), dwarf stars will be exploding.

    • The sheer size of 10^1100 makes the silliness unimaginable.

      Even if you sprint to to the end of the observable universe, that's just 10^26 m. So, the first nanometer is just a 10^-35 fraction. You'd still have to sprint back and forth 10^1065 times to get the right proportions.

      It is a nice article though. I think they're saying white dwarfs will eventually cool down enough to shrink below the Chandrasekhar limit and collapse into black holes, assuming no proton decay. If protons decay, then all matter will b

    • Good point. To put it another way, what you're saying is that if the length of the universe were equal to one day, then no matter how early we get up we're going to be watching black dwarfs exploding.

      We only exist in the moment when one day changes to the next.

      I'm bringing that up next time I get stoned.

    • by ceoyoyo ( 59147 )

      You might say a race, or a universe, ends at the point where nothing can possibly happen.

  • restaurant (Score:5, Funny)

    by aRTeeNLCH ( 6256058 ) on Wednesday August 12, 2020 @04:13AM (#60392881)
    I, for one, am most anxious about whether there will be a restaurant from which the end can be properly observed. And, honestly, a slight bit more anxious to know if by then there will be a cow willing to be eaten and capable of expressing that properly. And capable of operating a gun to shoot itself.
    • by jools33 ( 252092 )

      I've heard they do a particularly good Pan Galactic Gargle Blaster, the only problem is getting there.

    • It might be nice, but I have to admit, I am not a huge fan of Disaster Area. I think their music is rather overdone and lacks true originality. If youre going to dine at Milliways, you might as well stick around to the near end. And in that case, you will have to suffer through a a performance by Disaster Area.

  • No way! We have to find a way to reverse the process. After Big Crush another Big Bang could happen so there will be a chance for some future. If it expands forever there will just be... emptiness.
    So how can we do it? How can we destroy the universe?

  • "Computer, End Program."

    And then reality will fade away to a black room with an glowing orange-yellow grid on all surfaces, and The Picard will walk out of the room.

    The End.
    • by Nidi62 ( 1525137 )

      "Computer, End Program."

      And then reality will fade away to a black room with an glowing orange-yellow grid on all surfaces, and The Picard will walk out of the room.

      The End.

      Nah, someone will simply trip over the power cord for the server running our simulation and when they go to recover realize their backups have been corrupted for months.

  • Yes. But this one goes to 10^1100...
  • The Universe from start to finish to start to finish to star... https://youtu.be/o3Q7JYBkOHU?t... [youtu.be]
  • So what would all that mean for Earth?

  • I guess we will just have to wait and see how the universe ends, lots of love.

  • Based on what I'm reading in TFA, I'm not sure they're describing the "end" of the universe, as the /. title says, so much as the last time we see photon generation. Wouldn't there still be photons from the black-dwarf-explosion traveling through space until they get pulled into black holes? In these scenarios are neutron stars still in existence? I guess I'm realizing I'm not sure how to define the "end" of the universe, vs "the-point-when-the-universe-gets-really-boring". The beginning seems easier to

    • by ceoyoyo ( 59147 )

      It's the end of the universe because it's the last thing that happens. Those photons that get shot off can't possibly run into anything because everything that is not the star they came from is over their cosmic horizon. Neutron stars and small black dwarfs (but not black holes) exist, but you can't ever get from one to another, and they can't change in any way.

    • by flink ( 18449 )

      By the time this is happening, cosmic expansion means that there is no other object in the future light cone of the black dwarf. There is literally nothing for the photons to reach. Each photon is essentially in an empty observable universe traveling from nowhere to nowhere forever.

      The neutron stars continue to exist in a sense, but they will never interact with another celestial object, so it becomes almost a philosophical question at that point.

  • This is how the world ends, swallowed in fire, but not in darkness.

    I trust fast poison
    The stars to wink out
    And you, my love - and you.
  • The universe is a constantly expanding then collapsing entity. Once it collapses it explodes in another big bang event.

    Prove me wrong!

    -Look I'm a Scientist!
  • And then?
  • IIUC they've got several plausible answers, and no real way to choose between them. Even the "big crunch" hasn't really be ruled out, though it's less popular now then it used to be.

    • Yeah, I was gonna say there's entire books dedicated to nothing more than working through various scientific theories on how it could all end. There was just a new one released recently by Katie Mack (The End of Everything, Astrophysically Speaking) that covers several different theories. The possibility that it could just *BLINK* out of existence due to the Higgs energy field becoming unstable is a particular favorite of mine, though there are several other possibilities that are quite intriguing.

      The ide

    • The Big Crunch isn’t "less popular" as much as more and more evidence is against it. While science can’t know for sure, it is becoming increasingly unlikely that the Big Crunch will occur.
      • by HiThere ( 15173 )

        Probably so...but that's making an estimate in an area with lots of unknowns. Since nobody understands dark energy, any prediction of how it will act in the future is a shot in the dark. It *could* just reverse itself. And any estimate of the probability of that is based on gut feeling, not science.

        • What do you mean by "estimate"? All available known data says the universe is expanding with no contraction likely. This is from multiple readings from different methods and confirmed by multiple teams. This is not someone just guessing. Can scientists know 100% what will happen in the future? No, and they have never said that can predict the future with perfect accuracy.

          In the future if there is contradictory evidence, that does not mean that the existing evidence magically disappears. The existing evidenc

  • by Dunbal ( 464142 ) * on Wednesday August 12, 2020 @09:20AM (#60393433)
    Seriously there is so little we actually know, so much more we are discovering all the time, and a vast unknown well of knowledge that we can never possibly know because of the time and size scale we exist in, that making any sort of prediction like this is an exercise in fantasy only. An ant sitting on a tree in the 1400's and imagining the future of the forest could never have imagined the arrival of the gasoline powered chainsaw and the sawmill.
  • The dramatic detonations will begin to occur about 10^1100 years from now

    Whew, I originally misread that as 10^1098 and got worried the universe had cheated me out of 99% of my time.

  • Who's the moron who came up with the title. Jesus people it's a freaking thought experiment.

    "Gregory Laughlin, an astrophysicist at Yale University, praises the research as a fun thought experiment. The value of contemplating these mind-boggling timescales is that they allow scientists to consider physical processes that haven’t had enough time to unfold in the current era, he says."

    Not too mention there were already ideas for how the universe would end.

    "For example, some of the grand unifie
  • If the expansion rate will continue to increase we will expand faster then light speed at some point which would make it all go dark. Will that happens earlier than the last stars collapsing?

  • Nov 4, 2020: Trump wins second term.

  • I can hardly wait!

  • Thank goodness for that! On a first read, I thought we had just a measly 10^100 years left ;-)
  • Two years ago, there was a similar story, with numbers that are very very far away form 10^1100: https://science.slashdot.org/story/18/04/07/1856202/did-harvard-scientists-predict-the-end-of-the-universe

    What was wrong with the earlier story? Maybe we can just stop making stuff up?
  • This galaxy will only get bigger over time and is gravitationally bound. How is dark energy EVER going to change that exactly? My understanding is the Hubble constant shrinks over time meaning locally effects of expansion of the metric decrease... even as the amount of space and therefore the rate of aggregate expansion increase. So how do gravitationally bound systems get wisped away via expansion exactly?

    Sorry for the stupid question but I just don't understand.

  • When the simulation gets boring, they'll just turn it off... I predict in about 10^10 years. Wait around and see if my prediction is right!

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