Watching a deal on Stephen Hawking and it mentioned the powerful gravitational pull of the black holle, more powerful than light itself, and it got me to thinking about a way waya that could possibly be used to break the light barrier by using a black hole, so my question is this: If a black hole's greavitational force is infinitely more powerful than light, does that mean as it pulls objects into its singularity or center, do they break the speed of light barrier? After all, as a lighter object is pulled toward the greater gravitational force, it goes faster and faster and faster. We need to go at a speed of 18,000mph to break out of orbit. And objects in orbit, as far as I know, can travel up to 24,000mph. So is it possible to use the power of the black hole to break the light speed barrier?
In the Red Dwarf novels they did just that. Let themselves get sucked towards a back hole while adding speed with their rockets, and when they got to the point in the event horizon where reality started to go distorted enough to allow it, they cracked light speed, then they pulled free and escaped. Course, Red Dwarf is a comedy, and thus loaded with BS science, but you're not the first to think of it.
Hmmmm. That's an interesting question. If an object would have to reach light speed to escape from just before the event horizon of a black hole, could an object falling past the event horizon exceed light speed? The answer is: no. The event horizon is the hypothetical surface that represents the region from within which not even light can escape. If you were in a ship falling into a black hole and went past the event horizon, you would not notice anything unusual (provided the black hole was large enough that its gravitational field didn't have a sharp gradient at that point). You would not measure yourself going faster than the speed of light because relativity still applies. Those outside the event horizon could no longer see you, so they wouldn't measure you exceeding light speed (even if, somehow, relative to them you were). No observer anywhere could see you exceed light speed. Therefore, you can't be said to have exceeded it. If matter could defy relativity and exceed light speed falling into a black hole, it would sometimes emerge from the event horizon. Imagine you fell past the event horizon but lucked out and missed the singularity. You'd be flung back out into space, kinda like a meteor that just misses the Earth. Since that never happens, we can presume that objects inside the event horizon still obey relativity. The key to understanding is that nature conspires to prevent mass from travelling faster than light no matter how much energy is involved. Have two spaceships approach each other at 75% light speed...isn't their closing speed 150% light speed? No, because of time dilation and length contraction, neither ship will appear to be moving faster than light.
I thought the amount of entropy inside a black hole was too great for the laws of physics to function.
That statement is not necessarily technically correct, but the laws of physics as we understand them do break down at the singularity.
A blackhole and the singularity at the centre of it are two seperate things depending on how you define it. The event horizon is just the point where light can't escape, apart from that there is nothing overly special about it compared to a bit further out.
A black hole is no different from any other concentration of mass apart from the fact that it is infinitely dense. It does not necessarily have a hugely strong gravitational pull - and it is only once the event horizon is crossed that its gravitational pull becomes irresistable. Therefore, objects being pulled into a black hole do not necessarily break light speed, or even approach it.
Black holes are usually misrepresented in Science Fiction as well. Sure, you don't want to get too close to one, but the same applies to any massive body. If our sun was suddenly compressed into a blackhole it wouldn't alter the Earths orbit one bit.
Um, much ado about nothing this post to be honest, and the original question asked about the singluarity at the centre. It's assumed a full theory of quantum gravity is needed to know what happens at the singularity. As Bailey said, inside the horizon is nothing special - the Schwarzchild metric describes the spacetime (not including the singluarity at r=0) inside a Schwarzschild black hole as well as outside it. It just happens that there is a radius at r =2.mass at which there is a problem with the co-ordinates usually used to describe the spacetime, but the metric is still continuous there.
First let me say, I agree with the gist of your post. But then, everything outside of the observable universe is moving away from us faster than lightspeed. Though expansion of space is no real movement. The galaxies are not moving away from us with a certain speed. Rather space itself is expanding. At least that's what analyzing red shift data from far away galaxies suggests. An event horizon might just be the sort of phenomenon that prevents information exchange between areas of space moving faster than speed of light. It's difficult to say what's inside of the event horizon of a black hole. Possibly the event horizon is there to protect Einstein's laws, to protect us from seeing something that's faster than the speed of light - in our inertial system. Also, the collapse of a star into a black hole is a never ending story. Seen from the outside, the collapse never really finishes, but rather grinds to a halt. The closer you get to Schwarzschild radius, the slower time will pass. That's why black holes are also called "frozen stars". (OK, a "black hole" in some languages also has a second, sexually loaded meaning ) Anyway, the overall theory makes my head dizzy. Assume you're falling into a black hole. To the outside observer, you'll never reach event horizon, as time slows down when you approach it. Yet in subjective time, you'll reach Schwarzschild radius in finite time. You do have a point. Personally, I think there can be no singularity - a point of infinite density. Newton/Einstein's laws say there will be one, but quantum mechanics says this can't be true. It would hurt the uncertainity principle. I guess inside of a black hole space will expand to adjust and make room for all the matter forced into it. Much like the effect we call cosmic inflation. I'll admit, that's wild speculation.
That's true. Because although no material object or information can move at a speed greater than light, it appears that space itself can be "stretched" so that two spaceships on either side of it are getting farther apart at a rate that exceeds c. Of course, neither spaceship will see the other as light cannot traverse space that is expanding at a rate greater than c! I think the observations one would get from expanding space and from objects in relative motion will be the same. The "red shift" that one sees from a distant galaxy could either be a consequence of the Doppler effect (galaxy in motion away from observer) or of the intervening space expanding, lengthening the wavelength of the light. I don't think the effect is any different. And, to pull a page from Einstein's book, if two phenomenon behave the same way for all observations, perhaps they are the same in some real sense. Here's an interesting paradox: a black hole can increase in mass and, thus, its event horizon can move outward, encompassing a larger space. However, objects falling into the event horizon--from the point of view of an outside observer--NEVER reach it. They are steadily blue-shifted, their emissions shifted towards smaller wavelengths. So how is this possible? If a particle is never seen to reach the event horizon in the observer's time, how can the event horizon increase in the observer's time? Certainly it is not a coincidence. Right. That's the paradox I'm talking about. If the cause never finishes, how can the effect be observed? *random speculation follows* I've often wondered if the event horizon isn't a "plane of symmetry" of some kind. That is, nothing passes through the event horizon, there's just symmetric phenomenon on either side of it. Imagine objects fall toward the event horizon. In objective (outside observer) time, they never make it. Perhaps they simply coalesce just outside the event horizon, forming a cloud of particles all falling toward it, but that never reach it. Still, their mass does contribute to the overall mass of the hole and makes the event horizon expand. But nothing ever gets past the event horizon! Now, on the inside... Hmmm.
Ever stop to wonder if our 'verse is simply the interior of someone else's Black Hole? (No, NOT uranus... )
*Continuing random speculation - do not use anything mentioned in the following on your physics exams - YOU WILL FAIL! * So, on the inside of the event horizon as the star forms... The material near the surface will be in one relativistic frame and the material in the center will be at another, with all points in between somewhere in the middle. I wonder if the star stops collapsing? After all, to have a collapse, material from all regions have to move toward the center, but now material near the surface is in such a large gravitational field that it takes a very long time for it to cover any kind of distance. Perhaps the star reaches some new equilibrium point inside the event horizon and merely continues to burn. Since no matter can get past the event horizon, there will NEVER be enough matter for the star to "re-collapse." So the star continues to burn, its different layers at different rates. At some point, it will have consumed all of its nuclear fuel and--in the very far future--all available useful energy will have been used up. The interior of the event horizon will be cold and dark. This avoids a singularity completely. In effect, this model of a black hole says there's just stuff crammed up against its event horizon on the outside, and a star that continues to burn on the inside (although because of the different relativistic states of its layers, may burn in interesting ways!). The collapse stops with the formation of the event horizon and, since nothing else can get in, never resumes. Hmmm...
It is indeed. We're not limited to the here and now, we can imagine things trillions of miles away and billions of years in the future.
That falls apart when you remember that the state before a black hole, a neutron star, isn't actually burning anything.
Good quote. I fully agree. However, there is a measurable difference between Doppler-shift, caused by moving objects, and Hubble shift, caused by expansion of space. When space expands it transports lightwaves with it. Therefore, we can look further than 13.7 lightyears, the age of the universe. I've thought about this many times. Not sure though, if a black hole really can grow in mass. But then there is talk about black holes colliding, so there might be some dynamics with "frozen stars". Not to mention that stuff get's worse - and way above my head - when looking at real, spinning Black Holes. Then they form an ergosphere. Whatever that is. BTW, would't we see a red shift instead of a blue shift, when the photons ascend up from the gravity well to the outside observer? Makes a lot of sense to me, indeed.
That's actually pretty interesting, but it would be damn difficult to test, as the basic premise is "neutrons can fuse into another elementary particle". I mean, if a star comprised of neutronium doesn't exhibit any evidence of this kind of fusion, what are the chances we can test it in a lab? It's damn difficult to get neutrons up to relativistic speeds using our current accelerator technology. Hell, is it even theoretically possible in any sort of controlled manner?
There's nothing preventing a situation (a universe) in which it happened that cosmological redshift (of galaxies, say), and a conventional doppler shift were indistinguishable. It just happens that we can distinguish them, which is fortunate. In fact, the two effects can be combined to consider a general redshit effect, which would, for example, be used if there was a very distant spaceship emitting radiation travelling from us perhaps.
