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.”
Space ping
Is this article talking about the national debt?
I have a question if anyone here is enough of an astrophysics professional to answer it. As gravity increases, time slows and at the event horizon, time essentially stops. If that’s the case, then as a star collapses, time slows and slows as the gravity increases but if the collapse slows, how can it every finish and reach the point where time stops? Wouldn’t each black hole essentially be forever trying to finish forming but not finish forming until the “end of time”?
What, those modern physicists have never seen a National Geographics?
That doesn’t really answer my question. The equation for velocity is v = d/t or vt = d so as time (t) approaches zero, the distance covered also approaches zero. So it’s not simply a matter of the image being frozen but of the actual movement being frozen, too, at least from the outside frame of reference.
Well, that’s good. I don’t want a naked singularity in the first place.
If you were there, though, would it seem like not forever but as a very short amount of time, all things being relative.
Not touching that one at all...
But personally, I believe if B Hussein Obama is elected we'll all be living in a black hole (no racial connotations intended!).
Ray-Zizt! Now you peeps be callin’ Obama a black hole!
IOW: “Have you ever seen a grown singularity nekkid?”
What about 3 colliding singularities?...
Obama, Pelosi, Reid
“where the laws of physics do not apply”
If things really work differently at a singularity, then that’s part of the laws of physics too, and the laws of physics need to be revised to include that.
Problem is scientists really think that their “laws” rule and control the universe.
Wrong.
Scientific “laws” are an attempt to understand and describe the workings of the Universe. If the “laws” are wrong, they must be revised.
Since present scientific “laws” don’t explain the origin of the Universe, often referred to as the “big bang”, they are in question.
ttiwwp
ttiwwp
Does the singularity look like Sarah or like Hillary?
Alas, father time has greatly diminished my naked singularity!
Zeno’s paradox? Similar to the problem of movement toward a threshold. You can always divide the distance needed in half. So if you go halfway, you can then go halfway again, then halfway again, ad infinitum. Thus you never reach the threshold.
No to naked sigularityism. I you allow just one singularity to be naked you must allow them all. Stand up of the rights of the cloaked singularity.
;P
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.