No Naked Singularity After Black Hole Collision

Black holes cannot be naked... the event horizon will always be there to cover them up...

Black holes cannot be naked... the event horizon will always be there to cover them up...

You can manipulate a black hole as much as you like but you’ll never get rid of its event horizon, a new study suggests. This may sound a little odd, the event horizon is what makes the black hole, well… black. However, in the centre of a black hole, hidden deep inside the event horizon, is a singularity. A singularity is a mathematical consequence, it is also a point in space where the laws of physics do not apply. Mathematics also predicts that singularities can exist without an associated event horizon, but this means that we’d be able to physically see a black hole’s singularity. This theoretical entity is known as a “naked singularity” and physicists are at a loss to explain what one would look like.

Like any good physics experiment, an international team from the US, Germany, Portugal and Mexico have decided to simulate the most extreme situation possible in the aim of stripping a pair of black holes of their event horizons. They did this by constructing an energetic collision between two black holes travelling close to the speed of light, crashing head-on. Here’s what they discovered…

A computer simulation shows that two black holes of equal mass colliding at close to the speed of light — an extreme scenario — form a new black hole and release energy in the form of gravitational waves (Sperhake et al.)

A computer simulation shows that two black holes of equal mass colliding at close to the speed of light — an extreme scenario — form a new black hole and release energy in the form of gravitational waves (Sperhake et al.)

Actually, Emanuele Berti (JPL/Caltech) and his collaborators didn’t set out to embarrass a black hole; they were simulating some extreme collisions between two massive bodies, watching the ripples in space-time (gravitational waves) propagate. In this case, they were using the computer simulation (carried out by Uli Sperhake, who was working in Germany at the time and has since begun work at Caltech) to examine the gravitational waves generated when two black holes of equal mass were driven together, head-on, close to the speed of light. The two black holes then merged to form one large black hole.

The results from Sperhake’s simulation were very interesting. Unlike previous simulations examining lower-energy collisions, far more energetic gravitational waves were produced. So much so that 14% of the total masses of the colliding black holes were converted into gravitational wave energy. So far so good. If this extreme (and unlikely) scenario were to occur, perhaps we’d know what to look out for in the noisy LIGO data, and we might gain an estimate of how much mass black holes shed in these encounters. However, there’s another outcome to this research: black holes keep their event horizons no matter what is thrown at them.

This may seem like an obvious outcome to this experiment, but it has some significant implications for how our Universe works. In 1969, mathematical physicist Roger Penrose conceived the cosmic censorship hypothesis which states that no naked singularities can exist in nature (apart from the Big Bang 13.73 billion years ago). A space-time singularity is the point at which the quantities used to measure the gravitational field become infinite (i.e. a large star collapses due to lack of fusion and the stellar matter is too massive to support itself; it collapses to a single point, creating the singularity inside a black hole). Because space-time becomes extremely warped in the vicinity around this gravitationally dominant point, a boundary surrounding the singularity called the “event horizon” will form, marking the distance from the singularity that even light cannot escape. Any light emitted inside the event horizon can never escape beyond this boundary; anything straying too close to the horizon risk falling into the boundary of the black hole, never to return.

Comparison of space time warping due to several bodies (NASA)

Comparison of space time warping due to several bodies (NASA)

The event horizon is what gives black holes their name. If no light travels beyond the event horizon, and only stuff can fall in, a black sphere remains in three dimensional space (with a radius dependent on the mass held in the singularity, see Schwarzschild radius). So, any gravitational singularity should be dressed with an event horizon. However, mathematics predicts that singularities can exist without an event horizon, thereby making them naked singularities.

This is where Penrose’s cosmic censorship hypothesis comes in. Our Universe must have some natural ability where an event horizon will always be associated with a singularity. It would seem this new research confirms the British professor’s 40 year-old theory that a black hole cannot be stripped of its event horizon, no matter how violently it is treated. This is fortunate, as modern physics has no way to describe what a naked singularity would look like.

We hope it’s true,” Berti says of the cosmic censorship hypothesis, “because it basically hides the failures of general relativity behind the event horizon.”

Original source: Science News

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10 responses to “No Naked Singularity After Black Hole Collision

  1. I recall some speculation (a while back) that a very rapidly rotating black hole might create a naked singularity. While I don’t suppose the forces are even close to a near c headon, I can’t help wondering if anyone ever simulated that?

  2. “We hope it’s true,” Berti says of the cosmic censorship hypothesis, “because it basically hides the failures of general relativity behind the event horizon.”

    i realize that statement is somewhat tongue in cheek.

    But, practically speaking, if you can not test something even in principle, does it even make sense to talk about it from a scientific standpoint?

  3. Pingback: Centauri Dreams » Blog Archive » The Space Outlook from Kentucky

  4. Hi, Astrophysicists engaged in this area of research should simulate Triple Triangular (Pawnbroker) configured Collisions of Black Holes.
    These collisions create an Internal / External, Event Horizon Continuum, as each Black Hole sacrifices a sector of its External Event Horizon, which becomes the Internal Event Horizon. The Internal / External Event Horizon Continuum is the Event Horizon of a Black Torus. As the Internal Event Horizons interact, (negate each other) core collapse initiates jetting (twin jets). The torus
    becomes Gravitaionally open. It is a Jetting Black Toroidaal Object.
    Kevin Wilson
    CFSS
    London

  5. Pingback: The Naked Singularity Recipe: Spin a Black Hole, Add Mass | Astroengine.com

  6. event horizon must contain a singularity .It is true.But a singularity need not required horizon.Because existence of mass and energy or exchange situation of these two depends upon schwardzschild radius. There will be three types of black holes.1. A black hole with in schwarzschild radius.(contains mass and radiation energy)2.A black hole equal to schwarzschild radius.(contains only mass)3.A black hole out side schwarzcshild radius.(contains only radiation)A naked singularity comes under third category.Refer:1. Kodukula,S.P.: Heart of the god with grand proof equation – A classical approach to quantum theory , Lulu.com (2009) ISBN 9780557089956 2. Kodukula,S.P.: Cosmological focus on Particle Physics and Genetics, lulu.com(2009) ISBN 9780557077243 3. Kodukula,S.P.: Double Relativity Effect & Film Theory Of theUniverse,Lulu.com(2009) ISBN 9780557077120

  7. BLACK HOLE
    — James Ph. Kotsybar

    Containing nothing that’s ambivalent,
    more than dark, which would only be dreary,
    death’s non-spiritual equivalent
    crushes our intellect to theory.
    Passage through is most certainly
    one way, and thus it incites our speculation.
    What would occur, if we wandered astray
    into this singular aberration?
    It’s relative to where you’ve placed your clocks.
    From outside, we’d seem to fall forever.
    Beyond that, it’s puzzling paradox.
    We only know that we’d leave it never.
    A downward orbit is how it begins,
    and nothing’s jolly when gravity wins.

    PENT SILLS
    — James Ph. Kotsybar

    These graphite singularities
    contain universes
    unconceived,
    awaiting
    the Big Bang
    of inspiration, but
    narrative particles
    escape like
    Hawking radiation —
    gravity’s diminution
    evaporatively slow,
    nearly virtual,
    and random.

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