back to article What would happen if Earth fell into a black hole?

Black holes have long been a source of much excitement and intrigue. And interest regarding black holes will surely grow now that gravitational waves have been discovered. Many of the questions I am asked regard how “true” science fiction concerning black holes might be, and whether worm holes, such as those featured in …

  1. Anonymous Coward
    Anonymous Coward

    Naturally, we would no notice

    We'd be dead. Or rather that the (AFAIK) the gravitational waves that pulls us into the Black hole would tear us apart long before we reached it. What could survive? Perhaps an ant or a cockroach but not much else.

    Anyways, I won't (along with all the other commentards) be alive to try it out.

    1. Anonymous Coward
      Anonymous Coward

      Re: Naturally, we would no notice

      "the gravitational waves"

      gravity != gravitational waves

      1. Ian Michael Gumby
        Boffin

        AC's don't surf! Re: Naturally, we would no notice

        "gravity != gravitational waves"

        I don't think the AC or those who up voted him thought this through.

        What happens to the space time fabric if suddenly a massive black hole appeared inside this solar system?

        Hint. Find a pond / pool and toss a massive rock in to it. It goes splash now doesn't it?

        So yes, the waves would rip us apart long before what remains is sucked in to the event horizon.

        But don't worry... we wouldn't feel a thing. Since the wave front is traveling at the speed of light, we'd be torn apart before our nervous system could make sense of what is happening.

        So while the first AC was wrong about the waves pulling the planet in (That is gravity), he was right that it will be the gravitational waves created by the sudden appearance of a black hole that will kill us.

        1. Anonymous Coward
          Anonymous Coward

          Re: AC's don't surf! Naturally, we would no notice

          "I don't think the AC or those who up voted him thought this through"

          Same AC here - just to note that all I was commenting on was the (unfortunately) now widespread misconception that gravity was mediated by gravity waves.

          The instantaneous appearance of a black hole next to earth is such a bizarre event that I'm struggling to see the source of the gravitation waves BTW

        2. Rich 11 Silver badge

          Re: AC's don't surf! Naturally, we would no notice

          So yes, the waves would rip us apart long before what remains is sucked in to the event horizon.

          The figures given for the recently-detected black hole merger can give some context. If the merger happened 1.3Gly away and the signal only created a disturbance a thousandth of the width of a proton, then it would only disturb something one lightyear away from it by about a millimetre. Knock that down to 1AU and the disturbance would be on the order of 300,000km. Having, say, an 8 solar mass black hole suddenly appear in our solar system would be a lot, lot less violent an intrusion into spacetime. Earth might not be ripped apart, although I wouldn't want to be living on a fault line or on a coast at the time.

          1. Wzrd1

            Re: AC's don't surf! Naturally, we would no notice

            "The figures given for the recently-detected black hole merger can give some context. If the merger happened 1.3Gly away and the signal only created a disturbance a thousandth of the width of a proton, then it would only disturb something one lightyear away from it by about a millimetre."

            Two black holes merging does not make a solar system merging with a black hole - it'd be the equivalent of dropping a drop of water into the ocean of Europa, unnoticeable.

        3. Anonymous Coward
          Anonymous Coward

          Re: AC's don't surf! Naturally, we would no notice

          "Hint. Find a pond / pool and toss a massive rock in to it. It goes splash now doesn't it?"

          I'm not sure the analogy fits. A simple black hole doesn't emit sig. gw (AFAIK) except when another very large mass is in mutual close orbit. The two black holes that merged 'last week' emitted the largest amplitude waves at the point of merger but before the resultant object became symmetrical.

          Are you suggesting that the hypothetical 'appearance' of a black hole next to Earht would generate large amplitude gw just by 'appearing' ?

          (An interesting snippet is that the gw emitted by the Sun/Earth system are of the order of ~200W) BTW

        4. Wzrd1

          Re: AC's don't surf! Naturally, we would no notice

          "Hint. Find a pond / pool and toss a massive rock in to it. It goes splash now doesn't it?"

          Not really, gravity waves that would be that disruptive would have to originate from two black holes or a black hole and a neutron star, Sol couldn't produce such gravity waves when interacting with a black hole.

          Indeed, it's likely that the entire solar system could enter a galactic core sized black hole intact-ish.

    2. MyffyW Silver badge

      Re: Naturally, we would not notice

      the Black hole would tear us apart

      And there was I, at age 17, thinking Love will tear us apart

    3. Wzrd1

      Re: Naturally, we would no notice

      Not necessarily, a supermassive black hole, such as a galactic core singularity could actually bring a planet in intact.

      To be blasted by the incoming radiation below the event horizon.

  2. BoldMan

    Another reprint from The Conversation? Really?

    Bring back Tim Worstall if this is the level of articles we're going to continue to be subjected to.

    1. GrumpenKraut

      > Another reprint from The Conversation? Really?

      Why not? I much enjoyed reading it.

      > ...if this is the level of articles we're going to continue to be subjected to.

      What exactly do you criticize?

      1. Robert Helpmann??
        Childcatcher

        What exactly do you criticize?

        In the article? Given that it is presented in layman's terms (good deal, too, as I am not the best with physics), it should perhaps mention time dilation as a reason that no-one would notice a black hole popping up next to Earth. If we are going to indulge ourselves by using that as a scenario, we might better first discuss the black hole's motivation in doing so.

        This article is posted under the Science section. It would have been better to place it directly in Forums or Bootnotes as it does not even pretend to be news... wait a minute... I just went outside to have a look and no black hole, at least none that I noticed.

        1. mosw

          "we might better first discuss the black hole's motivation in doing so."

          Don't panic, it is clearly just to make way for a hyperspace bypass. I'm sure they will send us notice before doing so.

    2. Anonymous Coward
      Anonymous Coward

      Find Tim's blog and read a few articles, and you might change your mind. Toxic is the first word that springs to mind. He definitely toned it down for the Reg.

      1. Chris Miller

        Do you usually find it 'toxic' to have your preconceptions challenged? For Tim's own pieces there's certainly some NSFW language ("Flatulent Tosspottery" being one of his sections), but there's little in there that wasn't covered at some point in his Reg articles. The comments (largely unmoderated) are a whole 'nuther matter.

        1. Androgynous Cupboard Silver badge

          Well you've got this headline, or his scary views to choose from. Although this one really takes the biscuit.

          I did quite enjoy some of his articles here, although I didn't always agree with them. I have said that before. But he's still a certifiable, misanthropic loon.

          1. MyffyW Silver badge

            @Androgynous_Cupboard he's still a certifiable, misanthropic loon

            He is, isn't he? We do miss him...

      2. caffeine addict

        I'll admit I only read the first dozen or so articles on his blog, but they look pretty tame to me.

    3. Dan 55 Silver badge

      Aren't you comparing apples with oranges, since when did Tim write about science? (Apart from when he tried to claim the economy was a science.)

  3. This post has been deleted by its author

  4. Neil Barnes Silver badge
    Happy

    That's a first

    I've never had my food used to illustrated a black hole article before. I'm not sure if there's a moral there..

  5. Robert Ramsay
    Trollface

    Black Hole Firewalls

    ...or we might all vanish in a brief puff of smoke...

    http://www.scientificamerican.com/article/black-hole-firewalls-confound-theoretical-physicists/

    1. Anonymous Coward
      Anonymous Coward

      Re: Black Hole Firewalls

      Babel Fish...

  6. Ralph the Wonder Llama
    Happy

    For the Pastafarians among us...

    ...this is tantamount to The Rapture.

    1. TitterYeNot
      Coat

      Re: For the Pastafarians among us...

      "...this is tantamount to The Rapture."

      Praise be! All the faithful know that black holes are just manifestations of the Holy Colander, sent by His Noodliness to gather our eternal spaghetti...

      ~;;O;oo;O;;~

  7. WibbleMe

    You would think outer planets might go missing might be a clue

    Worse than being sucked into a black hole is colliding with the sun in the process

    1. Anonymous Coward
      Anonymous Coward

      Worse than being sucked into a black hole is colliding with the sun in the process

      That you all comment as if it mattered a fuck and we'd still be discussing it after?

      1. Grikath

        Re: Worse than being sucked into a black hole is colliding with the sun in the process

        Before that would happen the earth's glowy, and quite hot, inner bits would have come through the quite significant cracks in the crust. We'd have been reduced to greasy vapour well before any spaghettyfication could possibly affect us.

        1. Mark 85 Silver badge

          @Grikath -- Re: Worse than being sucked into a black hole is colliding with the sun in the process

          Not to mention that the atmosphere and basically anything not bolted down would have been sucked away first.

  8. Rol

    Obvious when you think about it

    A black hole consists of Higgs Bosun particles and nothing else.

    Matter falling into a black hole has their Higgs torn out and the rest passes through to another dimension.

    This is because Gandalf cast a spell insisting that Higgs cannot pass, and so the rest of the atom divested themselves of Higg and carried on into a dimension that has no gravity.

    If you were to find yourself on the other side of a black hole, it would appear like a sun, issuing fantastical amounts of energy.

    Interestingly, this energy, has proved itself to be a great protector of our bit of the universe, because the entities that live on the other side of a black hole, are extremely dangerous, what with their ability to ignore the affects of gravity, they could fly around on a whim swooping down to feast on us, like we were a Cornish pasty in the beady eye of a seagull.

    I will be starting a Kickstarter project soon, to try and capture one of them, if anyone is interested.

    1. Anonymous Coward
      Anonymous Coward

      Re: Obvious when you think about it

      YOU are one hillarious cat..

      1. Fibbles

        Re: Obvious when you think about it

        hillarious cat

        I believe the preferred nomenclature is 'hoopy frood'.

    2. Unep Eurobats
      Joke

      Re: Obvious when you think about it

      Stephen ... is that you?

    3. frank ly

      Re: Obvious when you think about it

      "... Higgs Bosun particles ..."

      Mr Higgs, stop disintegrating on the poop deck!

  9. Evil Auditor Silver badge

    I seem to remember having recently read something by someone who explained that black holes are indeed hairy. Can't be bothered to search the source though. But now for the most important questions: What would happen, hypothetically, if a black hole appeared out of nowhere next to Earth?

    Quite a lot of things, one would imagine. But the probably most devastating effect would be that the universe would be deprived of our heritage of cats and porn videos (cats' porn videos, anyone?). What a bummer.

    1. Captain DaFt

      "the universe would be deprived of our heritage of cats and porn videos (cats' porn videos, anyone?)."

      Which would explain why someone'd want to launch a black hole at us in the first place. :)

  10. GrumpenKraut
    Trollface

    Breaking news!

    Black holes suck even more than Windows 10.

    1. Mark Fenton
      Coat

      Re: Breaking news!

      When doing code reviews I used to refer to functions that return type "void *" as the blackhole of programming.

      :)

      Sorry sorry. I thought it was funny.

    2. Captain DaFt

      Re: Breaking news!

      "Black holes suck even more than Windows 10."[Citation needed]

      1. GrumpenKraut

        Re: Breaking news!

        > "Black holes suck even more than Windows 10."[Citation needed]

        Source: my funny south pole, spontaneously trolling.

  11. Mark Fenton

    Spaghettification - not always

    Being stretched out depends on the gravitational gradient - however for a given event horizon diameter the gradient could be pretty much any value.

    A very dense mass being a small sphere at the centre of the event horizon would have a much steeper gradient than a less dense mass that was just very big.

    Also - many people forget that escape velocity (and hence escaping from a black hole) only applies to projectiles.

    You don't need to reach escape velocity to get to the moon - you could walk there if there was a staircase long enough - in that case you are under power. The reason why our rockets go so quickly has little to do with escape velocity and more to do with energy density.

    You could drive a car to the moon (250,000 miles). But you need fuel. So you pull a fuel tanker. And your fuel consumption goes up. So you need more fuel...and so on.

    So you get a kind of fuel that is more energy dense - until the payload to the moon isn't quite such a tiny percentage of the mass of the fuel/payload combination.

    Trouble is, with the fuels that we currently use that are energy dense enough - they are hard to control - and go off, well, like a rocket.

    Got off track there a bit I think.

    1. Neil Barnes Silver badge

      Re: Spaghettification - not always

      Aye, but the point remains: if the gradient is small enough, spaghettification need not occur. If the mass is big enough, the event horizon is far enough from the point mass that the gradient need not concern you. But I have a vague idea that the mass needs to be on the order of a few galaxies, or maybe more.

      1. Mark Fenton

        Re: Spaghettification - not always

        The mass required depends on the radius of the event horizon...

        V = sqr (2.G.M/r)

        1. Anonymous Coward
          Anonymous Coward

          Re: Spaghettification - not always

          Here are some numbers using the mass of Earth (M) as a guideline...

          c= 299792458 m/s

          G= 6.6740831e-11

          M= 5.97237e+24 kg

          Key: Schwarzschild Radius = rs, Escape velocity at rs = evrs, Escape velocity at rs + 2m = evrs+2m

          I give the evrs+2m i.e. two metres out from rs to give an idea of the relative escape velocity, and thus the gravitational gradient that a tall person would experience.

          Mass= 5.97e+024 kg, rs= 0.0088700671 m, evrs= 299792458 m/s, evrs+2m= 19920866.79 m/s.

          So the Schwarzchild radius for an Earth sized mass is a smidge under 9 mm and the difference in escape velocity 2m from its event horizon is about 279871591 m/s - that's a pretty steep and unhealthy gradient.

          At ten times the Earth's mass...

          Mass= 5.97e+25 kg, rs= 0.088700671 m, evrs= 299792458 m/s, evrs+2m= 61779736.59 m/s

          The Schwarzchild radius is now a little under 90 mm and the +2m escape velocity difference is now about 238012721 m/s - still far too steep.

          At one hundred times the Earth's mass...

          Mass= 5.97e+26 kg, rs= 0.88700671 m, evrs= 299792458 m/s, evrs+2m= 166172922.8 m/s

          ...the ev difference has come down to 133619535.2 m/s - still too steep... In fact, it's not until we get to around a mass of 5.97e+35 that the ev difference is less than 1 m/s...

          Mass= 5.97e+35 kg, rs= 887006709 m, evrs= 299792458 m/s, evrs+2m= 299792457.6 m/s

          ...the Schwarzchild radius is now 887,006.09 km and whilst you might survive the difference in ev it would still be uncomfortable. To get to less than 1 mm/s difference in escape velocity we need to increase the mass by another factor of 1000, to 5.97e+38 kg, at which point the Schwarzchild radius becomes 887006709435 m, or 887,006,709.4 km - that's pretty big. In fact, that radius is about 44 times greater than the current distance of Voyager 1 from Sol.

          However, the estimated mass of our galaxy is between 1.15e+42 kg and 1.69e+42 kg, so it would seem that a sufficiently large BH would be between about 1/1930th and 1/2829th of our galaxy.

          Proviso: I think I've got the numbers right but wouldn't mind someone checking them.

          As DNA said "Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space..."

  12. Stevie

    Bah!

    What would happen?

    Maybe Donald Trump. It's as good an explanation as any.

  13. akeane
    Thumb Down

    Interstellar

    A weird, miserable looking bloke flying around to eqully miserable music, and a crap robot!

  14. adnim
    Joke

    What would happen if the Earth fell into a black hole?

    The Universe would be a much safer saner place.

    1. allthecoolshortnamesweretaken

      Re: What would happen if the Earth fell into a black hole?

      My dear mother-in-law would blame ME, that's what would happen!

  15. artificial bitterness

    Good GReith

    I always read black hole articles in Stephen Hawking's voice.

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