Posted on 10/13/2008 12:28:52 AM PDT by LibWhacker
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…
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.
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.”
Let me see if I have this right:
A black hole is a pile of matter so dense that it’s gravity sucks in photons.
The event horizon is the spot where the gravity is so great that it sucks in photons. Outside of the event horizon, photons can escape.
You ram one black hole into another and their gravity makes them stick together, making a bigger black hole. Presumably, the event horizon moves out a little because of the increased gravity of the increased mass of the black hole.
How many scientists did it take how long to figure this out?
Duh!
Not a big deal; they usually go away after a while.
Pictures?
There’s an NObama joke in there somewhere.
Ahh, Zeno's paradox. The solution (I believe) basically comes down to Plancks Constants, these are units so small that they can't be divided. It is also the idea behind Quantum Mechanics. A singularity would simply be all the Planck constants in a single point.
I was naked and single once.
Well, that’s good. I don’t want a naked singularity in the first place.
You and me both!...............
This is all on paper, right?
There’s an NObama joke in there somewhere.
Having zero instruments that have ever reported what happens inside a black hole, we have zero idea about the physics that goes on there.
Your post about time stopping is conjecture.
Further, we have no idea if time itself is quantized (comes in small indivisible units like a tickin clock) or if space is quantized (comes in small indivisible units).
The reasoning in your post fails to take the quantum nature of things into account.
Time is not standing still at the event horizon. That is only the ‘barrier’ where light cannot escape the gravitation field.
Your question is covered by Einstein’s Theory of Special Relativity. Time and distance is relative to the observer.
The effects on time and space at the singularity are still up for debate. I’ve seen different ideas from twisting space to create a wormhole to twisting time for time travel or even dimensional travel. Theoretical physicists love this stuff.
“14% of the total masses of the colliding black holes were converted into gravitational wave energy”
I wonder if they really said this using these words. This almost implies that gravity is a type of energy wave that can be emitted, comparable to eletromagnetic energy. The implications of that are staggering.
The way I understand it, it is not an “image”, it is the actual object. It is not frozen, but slowed down tremendously relative to the outside observer.
I would submit it does answer the question.
For an object falling into a singularity, time is unaltered, in much the same way as a traveler on a lightspeed spacecraft would experience it. It is only altered from the perspective of the observer.
I suppose that if a star were collapsing into a black hole, initially, the observer would see the star’s death frozen in time until the singularity had accumulated enough mass from its surroundings to “grow” the event horizon beyond the star’s initial mass, at which point the “blackness” would swallow up the ghost image.
This is a very racist projection, and I REALLY do NOT want to think about the physicals of “naked singularities” of most of the liberals in Washington who are voting for the next black hole ......
I've always opposed naked singularity.
Is the site down? I notice no new articles going up, or at least very few.
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