back to article Black holes can briefly bring dead white dwarf stars back to life

Black holes can bring dead stars back to life - even if it’s just for a few seconds, according to a new study. When stars teeter too close to the menacing voids, they can kickstart tidal disruption events (TDEs). Stars are yanked in towards the black hole by its strong gravitational field, and are eventually ripped apart by …

  1. Rich 11 Silver badge

    And at No.1 with a bullet...

    Black holes can bring dead stars back to life - even if it’s just for a few seconds

    Can anyone remember what we did with the body of David Bowie? I want to hear what he has to say about the afterlife. Give him a guitar, quick.

    1. SVV Silver badge

      Careful now...

      That headline seems to be bait for a joke so offensive and tasteless that it might lead to a permanent ban from this site.

      1. Anonymous Coward
        Anonymous Coward

        Re: Careful now...

        That headline seems to be bait for a joke so offensive and tasteless that it might lead to a permanent ban from this site.

        Wee Jimmie Krankie's still with us, so that'll reduce the tastelessness quotient, and you'll probably get away with the post being deleted by the moderator.

        Give it a try. If your pseud gets fried, I'll post a fulsome ebituary in the general comments forum of the Reg, to accompany the tumbleweed and lost souls there.

  2. Anonymous Coward
    Anonymous Coward

    Avengers Infinity War


    Restart the forge?


  3. This post has been deleted by its author

  4. TRT Silver badge


    that the headline lacks the word "suck".

  5. Sgt_Oddball Silver badge

    so let me get this straight..

    Sucking it up makes it go nuclear for a few seconds... realatively speaking.

    How long of you were watching a tad closer?

  6. David Roberts

    End of the world as we know it?

    Over a very long timescale super massive black holes are consuming everything.

    What happens next?

    1. John Brown (no body) Silver badge

      Re: End of the world as we know it?

      It all sucks up into a primordial superblack hole, then it belches and a new universe is created?

    2. Monty Cantsin

      Re: End of the world as we know it?

      Since the universe is expanding, there'll always be stuff out of the reach of black holes. Eventually, even the black holes will evaporate due to Hawking radiation. Over a big enough time scale, all particles will decay and we'll be left with a universe populated only by leptons and photos, each so far apart from each other that they never get the chance to interact. An ever expanding cold, dark universe where even entropy no longer exists, continuing for eternity.

      But the good news is that the canteen has burgers on today.

      1. The First Dave Silver badge

        Re: End of the world as we know it?

        What do photo's interact with now? I thought they were passive objects...

    3. Ken 16 Silver badge

      Re: End of the world as we know it?

      Wait and see, like the rest of us.

    4. Anonymous Coward
      Anonymous Coward

      Re: End of the world as we know it? - What happens next?

      I don't know, but if it involves supermassive black holes Rule 34 applies.

  7. 89724102172714182892114I7551670349743096734346773478647892349863592355648544996312855148587659264921 Bronze badge

    Very worrying, the prospect of white dwarfs in Uranus.

    1. Spherical Cow Bronze badge

      Is that an I or an l in your username?

      (Uppercase 9th letter of the alphabet vs lowercase 12th letter of the alphabet)

      1. Anonymous Coward
        Anonymous Coward

        Is that an I or an l in your username

        OT but that is surely one of the most annoying bad decisions in designing a typeface ever made.

        I keep all my passwords in a secure local app on my phone. The other day I had to use one of them on a laptop. After three attempts I realised what the problem was.

        The answer was to paste into an office application and change the face, thus finding where the problem was (one capital I and one lowercase l). But whoever decided to omit the crossbars on capital I should be taken out and shot. As I'm not vindictive and nasty, just shot in the backside with BBs. But still, shot.

        1. Chris G Silver badge

          Re: Is that an I or an l in your username

          That's the case with modem passwords too, when you read off the initial password from the label, I have had a few with confusing 'I's 'l's and 'O's '0's.

          1. jmch Silver badge

            Re: Is that an I or an l in your username

            O vs 0 - that's why I like fonts with the diagonal crossbar across the 0, although usually the width of the O is also (upon closer inspection) distinguishable from the narrower 0.

            I vs l on the other hand is awful!!

            1. Symon Silver badge
              Paris Hilton

              Re: Is that an I or an l in your username


              "Use only Easy-to-read characters"

              c.f. A Farewell to Anus.


      2. This post has been deleted by its author

      3. This post has been deleted by its author

  8. Anonymous Coward
    Anonymous Coward

    Unintelligent design

    The more that is found out about this kind of thing the more apparent it is that life in the universe is incredibly insignificant. There was a happy period in astronomy when it seemed that everything was nicely ordered - from the time of Brahe to the mid-20th century. Smaller things went round bigger things and so up to the level of galaxies. And now it turns out the universe is full of black holes, stars being destroyed, radiation sources that if they happen to point in the wrong direction could sterilise planets, or at least wipe out all our electronics...if the Judaeo-Christian god wasn't a myth, we'd have to postulate a most unpleasant sense of humour.

    1. Chris G Silver badge

      Re: Unintelligent design

      Cue ' The Church of God the Utterly Indifferent' courtey of Kurt Vonnegut jr.

      1. Michael H.F. Wilkinson Silver badge

        Re: Unintelligent design

        Utterly indifferent indeed. Whenever you shake your fist at the universe, shouting "It's not fair!!" the only answer you can expect is "So?" although no answer will be forthcoming, of course. I tend to think that if a god exists it can either be omnipotent or benevolent, but not both at the same time, given the indifference of the universe to all we hold dear on our little blue dot. I therefore cannot be bothered to believe in any of that kind of mythology, although creation myths are very interesting, not because of what they say about cosmology, but what they say about people, as Terry Pratchett put it so eloquently.

    2. jmch Silver badge

      Re: Unintelligent design

      "if the Judaeo-Christian god wasn't a myth, we'd have to postulate a most unpleasant sense of humour"

      Well, you just have to read some old testament to realise that ol' Yahweh not only has a most unpleasant sense of humour, but is, in effect, a narcissistic, egotistical, petty, vengeful and all-round unpleasant bastard.

    3. Destroy All Monsters Silver badge

      Re: Unintelligent design

      That's what comes from living in an exploding clockwork.

      I'm still of the opinion that the best times where Epsilon to 10^(-32) s. Such richness and dense diversity. Now it's just a cooling dumpster fire.

      > Judaeo-Christian god

      Btw, these two entities aren't the same at all. Yes, it is traditional to cover the divergences by a nice gaily colored tapestry. Probably better that way. But still fake.

      1. Anonymous Coward
        Anonymous Coward

        Re: Unintelligent design

        Yes, tribal thunder god vs Osiris cover band.

      2. Anonymous Coward
        Anonymous Coward

        Re: Unintelligent design

        "Btw, these two entities aren't the same at all."

        My theology degree says you are wrong, but probably not for the reason you think. The concept of "God" changes throughout the OT and the NT; it takes about half the OT before the Hebrews decide that the One God they worship is the Only God* (a different concept), and it takes 300 years for the Christians to persuade the Roman Empire of the same thing. The fact that the Catholic Church backslid into Trinitarianism is neither here nor there, since many religions do this. The Jewish equivalent is that some sects go in for a kind of rabbi-worship, just as do some Muslim sects.

        Of course, the first step on the way to No God is to realise that there can be at most One God, which is why it's so dangerous, if you want to keep people subjected to a paternalistic system.

        *Ba'al and Rimmon get press in the OT which makes it clear that they are the gods of people who haven't signed the contract. But the Ba'alists held down the Yahwists for over a hundred years, as is darkly hinted at in the story of Ahab and Jezebel. Personally, I root for Jezebel.

        1. Paul Crawford Silver badge

          Re: Unintelligent design

          I think most would root Jezebel

  9. Named coward

    understatement of the year?

    If a black hole is too small, its gravitational effects are minimal.

  10. Reid Barnes

    We have been fascinated by Stephen Hawking’s black holes for over a third of a century based on Einstein’s General Theory of Relativity, but eventually Hawking informed us they are not really black and there is no event horizon exactly. Everything from ‘black holes’ to dark energy and the accelerating universe is theorized using Einstein’s theory. Einstein claimed that the bending of light passing near the Sun, famously measured by Arthur Eddington during a solar eclipse, and also that the precession of the orbit of Mercury around the Sun were due to space-time deformation as characterized by his theory. In essence, he claimed that the explanation for the phenomena is that the geometry near massive objects is not Euclidean. Einstein said that “in the presence of a gravitational field, the geometry is not Euclidean.” But if that non-Euclidean geometry is self-contradicting, then Einstein’s explanation and his theory cannot be correct. How can it be correct if the title of the Facebook Note, “Einstein’s General Theory of Relativity Is Based on Self-contradicting Non-Euclidean Geometry,” is a true statement? Just check out the FB Note, at the link:

    1. Solarflare

      I'm sorry, you've confused me here. I'm not sure if it is the way you've written things, but you've lost me somewhere by Venus, I believe. You seem to have created an account on here just to link to a note you have posted on your Facebook account, and you are saying that essentially 'Einstein was wrong if Einstein was wrong!'. I believe that's called tautology. Now, I could go on to Facebook to read your post, but I have no wish to log in to that site, so either post what your point is here (not sure how it is relevant regardless) or give it up and toddle on.

    2. fajensen Silver badge

      Who Cares if it is "correct"?

      It's a model, we can calculate and even predict stuff with it, quite a lot of stuff actually. Which means it is a very good model. When a more "correct" model comes along, we can calculate and predict even better. Even then "Einstein" will still work, just like Newton and Maxwells models still work as long as one is not doing Quantum Electrodynamics (where they kinda work).

    3. Little Mouse

      "the geometry near massive objects is not Euclidean"

      Ok, I'll bite.

      The bending of space/time means that space is "non-Euclidian" everywhere, but the effects are more noticeable closer to massive objects, and as close-to-negligible-as-makes-no-difference away from them.

      There's no contradiction. The same effect is happening everywhere. It's just hard to observe or measure in most places.

  11. Rol Silver badge

    Join the Q

    The thing that puzzles me the most about black holes is the way that particles and radiation manage to inexplicably escape the inescapable.

    I have a theory though!

    Welcome to Q space (short for quantum space, but also a tip of the hat to Star Trek)

    Q space is a dimension that from our perspective lacks time. From the perspective of something entering it, not so.

    A particle will enter Q space if its energy level rises above the threshold level for that particle, and remain in Q space until that excess energy is dissipated, at which point it exits Q space and returns to normal space.

    We see all the time how molecules transcend states from liquid to gas based on the amount of energy present, and so it isn't such a huge leap to consider fundamental particles also transcend to a state that better accommodates their energy level.

    In quantum tunnelling, the electron does not pass through the insulating layer, but instead traverses that space in the Q dimension where the obstructing insulator doesn't exist. So, the probability curve is actually the likelihood of an electron getting a sufficient boost of energy to carry it into Q space for the time required to jump the insulating gap. Although precise measurement would show that not a jot of time had passed between the the particles disappearance and reappearance.

    At this point I'd like to mention the observations made while firing neutrinos through the Alps, and that some of these particles appeared to travel faster than light. Yes, those particles got an energy bump along the way and spent some of the time in Q space, which as I explained, is no time at all, and thus would give rise to the faster than light results.

    Now I've postulated that Q space is beyond our time frame, and it might also be true that normal space gravity has no sway in this dimension. In which case I have satisfied myself as to how particles manage to escape a black hole, but if this isn't the case then let me introduce you to Z space, which is the next energy level up from Q space, where the gravity of our, and Q space doesn't exist, thus allowing particles to break free from a black hole.

    Now what about Q space v's Inflation theory...the more I think about Q space the more I like it.

    In short, if by using all of the dimensions you are familiar with, you still can't describe the phenomena that you see, then you're toolbox is clearly lacking a dimension or two.

    1. Anonymous Coward
      Anonymous Coward

      Re: Join the Q

      I assume that's a joke post (the superluminal neutrinos) but I downvoted it because it isn't funny or witty.

      The way particles escape black holes is easy to understand, see Hawking radiation.

      1. Rol Silver badge

        Re: Join the Q

        You don't need to be able to understand what I've said. Just accepting that current theories are even more of a joke would be a good start.

        It's a pity teaching imagination has an upper age limit in single figures.

  12. bombastic bob Silver badge

    'source level' reactions and reactivity addition

    Just to add a little physics here...

    The problem I see with eddy currents 'kick starting' a reaction in the white dwarf is that the sudden addition of reactivity [i.e. the gravitational compression] is *ALSO* likely to cause an uncontrolled reaction and *EXPLOSION* rather than a 'kick start' of the star.

    Here's why:

    Fusion and fission share a few similar *kinds* of parameters, reactivity being one of them. In the case of fusion, a major part of the reactivity consists of heat and density. The fusion reaction in a star is stable because the expansion force from the fusion reaction is balanced by gravity. Too much of one, the star goes 'boom', or collapses onto itself and goes out.

    I would expect that because one fusion leads to another, you'd have a lifecycle time, delaying effects, and 'reactivity' (related to the effective neutron multiplication factor for fission; for fusion, it would be related to the ability of the energy from one fusion reaction to trigger others). When you have a sudden increase in reactivity, it's likely in a fusion reaction (as it is in a fission reaction) that you get a sudden 'jump' in the reaction rate that's somewhat proportional to the reactivity addition rate (this would be due to various factors that would be common in the reactivity equations of both fusion and fission). When the power levels of a nuclear reactor are unstable [a lot of chaotic activity, like a shut down fission reactor or a 'brown dwarf' star] then sudden spikes in the reaction rate might trigger an unknowable "super power level surge", high enough to explode instead of 'just starting up'. Or not.

    The SL-1 incident (see ) was a case where a shut down fission reactor went 'prompt critical' due to sudden reactivity addition, and experienced a 'prompt jump' in power levels (followed by 'prompt criticality' where power multiplied in microseconds instead of 100's of milliseconds) from a shut down condition to a 'thousands times maximum' power level (20GW according to the article, in a 3MW reactor) in a few milliseconds, burned nearly ALL of the nuclear fuel in that time period, and caused a 'water hammer' when all of the cooling water covering the core suddenly flashed to steam and pushed the remaining water up like a big piston, faster than you can blink, forcing the reactor vessel and attached components to jump 9 feet into the air, etc. etc. very very bad contamination, core meltdown, dead people, yotta yotta. Yuck. Photo of what was left of the the melted/sploded core on the web page.

    Assuming that sudden dwarf star restarts might act *like* *that*, because of the addition of reactivity by tidal forces and other 'black hole' things, if it's too quick, dwarf star go *BOOM*. My opinion.

    1. fajensen Silver badge

      Re: 'source level' reactions and reactivity addition

      *ALSO* likely to cause an uncontrolled reaction and *EXPLOSION*

      I think nobody will notice a mere Teraton "nuke" going off near a black hole - too noisy there. With all those GeV X-rays being sloshed about by that mass being sucked in and the polar mass ejections at about light speed.

    2. tfb Silver badge

      Re: 'source level' reactions and reactivity addition

      Yes, the reignition events are similar to type I supernovae so, yes, they're pretty big bangs. Type Ia supernovae are also related to events that happen with white dwarfs: in that case it's when they're in a binary of some kind and accrete enough matter from their partner to reignite fusion.

  13. Anonymous Coward

    Considering that tidal forces normally pull bodies apart, I wondered what forces were involved, and in the PDF found this:

    "Several deformation modes are active during typical disruption encounters. In the x-y orbital plane of the binary system, the star will experience tidal stretching along the direction connecting the black hole to the WD, and tidal compression perpendicular to this direction. The star will also undergo tidal compression in the direction perpendicular to the orbital plane. Compression perpendicular to the orbital plane is significantly greater than that in the orbital plane, and is the primary mechanism that could, in principle, ignite nuclear reactions in the WD."

    So parts of bodies not on the orbital plane don't like their own orbits and try to follow ones that cross thru the main plane, and this effect is great enough to trigger fusion during closest approach (several Schwarzschild radii they say). And a white dwarf could make repeated passes, getting a fusion booster shot each time...

    Sounds like the setting for an SF story by Robert Forward. :-)

  14. Anonymous Coward
    Anonymous Coward

    Wow! signal

    I did have a thought that this *might* also explain some FRBs as well.

    If the events are normally quite rare then perhaps some radio bursts are geometrically different to others accounting for the strange polarisation and other anomalies.

    Could the Wow! signal have been an early and as-yet-unexplained slower radio burst at a lower frequency and "Big Ear" picked up a harmonic? Its just possible.

    (scuttles off to do some more calculations, given event was at minimum D/2 based on the observation in only one horn rather than the other and essentially frequency stable over that time)

    Similar events might be seen on satellite TVs if they had a wide enough bandwidth using a temporal phase sequencing system based on locking the receivers to MSF or GPSDO and off-site data processing.

    In this case the harmonics might make detecting them harder but compensated by larger number of nodes in the system (eg tens of thousands over the UK) using the lower band on the LNBs around 10 GHz and

    have it "lock in" when it detects something strange.

    FRB@Home anyone?

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