Given a black hole what happens if you collide it with an equivalent mass of antimatter? Since matter disappears in matter/antimatter collisions leaving only photons, whose energy exerts gravity, would you then indeed wind up with a black hole composed only of photons? What does an atom ultimately turn into in a black hole anyway?
When matter combines with antimatter the two don't negate each other, they combine and transition to their combined energy via E=MC2. If you combine 1 KG of matter and 1 KG of antimatter, the result is 2KG * (C*C) = E... which is to say a really really big explosion of energy. Furthermore, photons don't possess mass, and so can't "exert" gravity. If they could exert any gravity whatsoever, they would be the most massive things in the universe due to relativistic mass dilation. I believe what you mean is that photons travel in space-time, which is bent by gravity... meaning photons are subject to the effects of gravity just like the rest of us. As to what happens to matter beyond the schwarzschild radius (inside the black hole)... well, here there be dragons. QM is good at describing small things, but is currently useless when describing massive things. GR is good at describing massive things, but has no framework whatsoever to address small things. This means that something which is both very small and very massive is a total question mark to modern physics. There is some organization of the matter, but we are unable to describe it with any degree of certainty. The above paragraph is important to understand before you can address your "black hole composed only of photons" assertion. Whatever becomes of the matter after it crosses over the schwarzschild radius, it is very likely that using terms like "photons" are not going to accurately describe it. In any event, I believe that the black hole would "freeze" the photon back to a matter state from its energetic state. Meaning shining a flashlight into a black hole adds to its mass. That said, your fundamental question was "what would happen if you dropped an equal mass of antimatter into a black hole?" The answer is the result would be a black hole which has twice its original mass. Black holes just sit there and eat. They don't care if they are eating photons, matter or anti matter. If something has mass (or its equivalent in energy) and falls into a black hole, then it increases the mass of the black hole. Anti-matter has the same mass of its matter equivalent... and so that mass is added to the black hole. It should be noted that it is accepted by modern theorists that Black Holes are losing mass due to Hawking Radiation. I am not a physicist, rather a cosmology hobbyist, and I have to admit, I don't really get Hawking Radiation. That said, what I do understand of it involves a process very close to what you originally offer (virtual particles being created and one falls into the black hole the other escapes), and the result is (after enough iterations) no black hole. So your original question is not exactly a novice question. Does that get at what you were asking?
I just reread my post, and I think I could simplify it tremendously on a second attempt... here goes. Gravity is an attractive force only, and there is no repulsive gravity. Like OU, gravity can't do anything but suck. Gravity's effect on space-time relates specifically to the mass of the matter in question, and does not care about the source of that mass. Since an anti-particle of any flavor possesses the same mass of its particle equivalent (a positron weighs the same as an electron), the result of combining the two without letting any energy escape (since nothing escapes a black hole) is that you've simply added 1+1 and gotten 2. As to photons, you must remember that photons do not possess mass. An infinite number of photons would weigh literally nothing at all. Since the black hole describes the shape of space-time as the result of the interaction with mass... there is no number of photons in any density which would result in a black hole. E=mc² describes the equivalence of matter and energy. You should think of that relationship similarly (though not exactly) as the difference between water and ice, transitions of a single thing. Extending that metaphor, matter would be analogous to ice... as it represents the less energetic state. Extending that metaphor even further, a black hole can be thought of as a freezer. If you pour energy into a black hole, the result is going to be an increase in mass. Since energy can't possess mass, the explanation is that the energy has been frozen into matter. In summary, if you put matter in a black hole, it gets bigger... if you put anti-matter into a black hole, it gets bigger... if you put energy into a black hole, it gets bigger. There is to my knowledge only one exception to this which is Hawking Radiation... but I don't understand it well enough to explain it.
My answer to the original question is that the black hole would cease to exist. Black holes exist because they have so much mass in an infinitely small space. When matter comes into contact with an equal amount of antimatter, the result is an explosion of energy leaving neither matter nor antimatter behind. Therefore, if the matter of a black hole came into contact with an equal amount of antimatter, then the two would annihilate each other leaving only energy and photons, neither of which has mass to exert gravity. It would be a hell of an explosion.
We don't know if antimatter behaves like matter or even opposite to it. Anti-matter may not form blackholes. If so, how can you get an equivalent amount of anti-matter for your collision? We don't know how much anti-matter exists in the universe.
Let me get this straight. OU is like gravity: It sucks. Aggie is like Hawking Radiation: No one understands it. However, somehow through enormous sucking powers, Aggie is shunned and manages to screw everything up.
If the matter and antimatter annihilate each other, then what would cause the gravity of the black hole to keep the energy from being released?
mia1994 is a lot more eloquent than most of the stuff I read for half an hour before I posted. At first glance I too would think the black hole would disappear in a massive photon explosion since there would be no mass to exert gravity any longer. Apparently some believe the energy of photons exert the gravity. Some describe a photon as an alternating collapsing and reanimating wave of the electric and then magnetic force along a path. If space time curvature is the reality, and not a mediating particle like a graviton, then I would think mia1994's description would then at least beg into existence some theories as to what is going on inside the event horizon of a black hole at the time of collision. If space time does curve, then its lattice work might react like an atmosphere when near a black hole. If matter and antimatter do indeed collide, photons form and gravity lessens, then space time curvature snaps back and becomes less dense. Perhaps the photons recondense/decay like water vapor back to matter, gravity kicks in again and prevents the photon explosion. So what good are dimensions if space-time curves? Wouldn't there be reality beyond space-time that would have to contain space-time that didn't curve? And mia1994 you might be the one to ask why time slows down for matter accelerated to near the speed of light. All I can figure is that is is a subjective localized thing as matter becomes more laden with mass, it slows down sort of like atmos and molecules slowing down as tempurature falls. The more massive you get the harder it is to slug that mass around, including chemical reactions. So time doesn't really slow down, it just seems that way.
Don't have a lot of time, I'll post more later... that said, time doesn't "seem" to slow, it actually slows relativistically. This is a function of relativity and it is not theoretical, it has been observed repeatedly. It must be accounted for in GPS satellites otherwise they return incorrect locations. Relativity may be incorrect, but time/mass dilation and length contraction (predictions of special relativity) have been observed and are fact.
I'm going to stick to the relativity bits for this post, because those are the parts that I'm comfortable with. The discussion of the interiors of black holes are beyond modern physics, so I'm content to let opinions differ until someone can source a physicist. First off, let us be clear and precise. The difference between time being slow and seeming slow due at relativistic speeds, is the same as the speed of light being constant and the speed of light "seeming" constant. This is not said as an analogy, but rather as a fact... one requires the other. We know that the speed of light is constant because it has been observed. Furthermore, we know that relativistic speeds result in time dilation because it has been observed. Second, General Relativity says that objects influenced by gravity are the same as objects traveling at relativistic speed, and are also subject to time/mass dilation and length contraction. This has also been observed... in fact one of the ways (but not the only way) it is observed is as gravity. In General Relativity gravity is not recognized as a force, but rather as a geometry of space-time... or dimensionality (length times 3 + time). That's the 30,000 ft view. It is the accepted physics and many of the technological innovations we enjoy either operate because of these principals or have to be tuned to account for them. The things they predict are practical and we experience them daily. Much of what you wrote, Bettik, I frankly don't understand where you are coming from. That said, this one stood out to me:
The original question could be rephrased as "What happens when two black holes collide if one of them is composed of antimatter?" First of all, the approximation of two black holes would cause some very interesting effects as their gravitational wells interacted; the nature of the effects would depend on the approach angle and velocity. Secondly, we don't know what particles do with their identity inside the event horizon, but it is not unreasonable to suppose that they do not all become and remain generic matterons (antimatterons). Anti-up quarks would likely interact differently with up quarks than with other particles. The distorting effect of the other hole's gravity and the possible (likely?) nonuniform nature of the mass therein contained mean that we are not looking at one big annihilation, but rather at a complex series of collisions. In the end, I suspect mia1994's prediction of a bigger black hole is most likely what would occur, but depending on the collision vectors and other factors far beyond my ken, there may well be quite a few particles and photons (assuming one doesn't count them as particles) emitted. By quite stretched analogy, I imagine two mud pies colliding: they stick, but the energy of the collision is sufficient to free formerly entrapped bits of mud from each. No, I am not a physicist either. Sorry.
This is my problem with the annihilation conclusion... unless we are presuming that all mass of the black hole is contained in a single point coordinate, then the interaction can't be gravitationally simultaneous (relativity of simultaneity). If all of the gravity is not instantly and entirely negated then any resulting "explosion" is going to be contained by the gravity well (not even light could escape). If the energy is contained entirely, then equivalency would seem to require that the energy express mass (condensing the energy to matter), thus not allowing any future interaction to result in escape velocity either. Picture the mass of the black hole being contained in an area the size of a golf ball. Even if the entire golf ball is instantly converted to energy, gravity can still only be communicated at c... meaning the "new" energy on the left side of the ball is still going to be experiencing the gravity of the "old" matter from the right side of the ball. That gravity will still be enough to prevent left energy from escaping, while left's former gravity will prevent right from escaping. That energy contained in such a small area, even if for the shortest instant, is going to result in the creation of massive particles. These new massive particles would be sufficient to maintain the gravitational curvature of the black hole, while the gravity continues to freeze out new particles from the rest of the energy. Again, this presumes that the singularity would allow distinctions like "matter/antimatter" to remain relevant, and I don't believe that is the case. As to your points on approach angle and velocity... I absolutely agree, and I think you should add angular momentum (spin). All of these factors could easily be sufficient to cast away the "colliding" body before the two mass bodies could ever meet. The result would be the two black holes pushing each other away with great velocities.
I'm only a musician. But my guess would be that gravity affects antimatter and matter the same way, as they would both have mass. So whatever happens when matter and antimatter colide would happen within the singularity (as the singularity would most likely also pull in regular matter), in the exact same way as usual--however since we can't look into a singularity (and as I understand it we aren't completely sure what happens insde). I always wondered this: I'm completely in the dark on the scientific side of things, but are there any theories about singularities can reach a critical mass of their own? I always wondered if the big bang could have been singularity-related--that maybe stars go supernova, turn into singularities, the singularities collide, and eventually you might have another big bang...this is all based on my fond imaginings and certainly not any deeper scientific reasoning, but I always imagined that it might be so.
If there was a big bang, then it would not be "singularity related" it would in fact be a singularity. I see no problem with your theory specifically, as long as you recognize the constancy of mass/energy. Which is to say, each explosion would result in a smaller (less massive) "universe" than the one which preceded it. The one potential catch would have to be that in the time between the black hole forming and the singularity "erupting", all of the mass/energy of the old universe would have to pass beyond observation... otherwise the universe we observe would not be isotropic... which it seems to be. There may a problem with scale here, meaning that it may not be possible for all of the mass/energy of our universe to have been contained within a single stellar body which could then collapse to form a black hole... but I wouldn't even know where to start with that.
Here is the antimatter podcast. There are lots of sections which are near the point... but they don't address it directly... I'm still looking. The Link
Found it! There is a problem on the site, but I found it in the google cache for episode 73 (question show 8). This question is answered over a much longer area than what I've quoted here, but I thought this was the most relevant bit. If you want to read the whole question here is teh cahced version:The Link
On the subject of curved space-time... It is important to understand that in General Relativity "space-time" does not represent some other fundamental element or property of space, rather it is the the actual physical geometry of space itself. Special Relativity argued that distance and time were not desperate concepts but were expressions of the same concepts of dimensionality. Altering the expression of one, changes the expression of the other. This is a fundamental requirement to have the speed of light be a constant. Special Relativity said that movement fundamentally warps space and time between observational vantage points... which is to say, that something in motion experiences less time relative to something which is relatively stationary. As an aside, it is a SR mind bender to point out that Relativity does NOT recognize a fundamental state of motion. If two objects are separating at 2mph it is valid to say that either is in motion while the other is at rest. This is to say, that both bodies will CORRECTLY observe time slowing down for the other. This is freaky. General Relativity takes that a step further and says that those individual warps to space and time which are made by individual velocity, can also be made by the influence of mass. Which is to say, that you can warp space and time for you, by moving fast... but you can warp space and time for a region by introducing mass. The warp of space and time will introduce a number of phenomena predicted within Special Relativity, but would also make any objects in this warped space and time "fall" in on each other. This is a description of gravity, where gravity is NOT a force being exerted between objects, but rather a flexing of the geometry of space (and time) we inhabit. If it was the former, then only massive bodies could interact... but the latter, since it addresses the entire geometry of space and time, effects ALL bodies occupying space and time whether they have mass or not. A black hole is the description NOT of an object, but rather what that mass of an object has done to its surrounding space-time. Specifically it refers to a warp or curvature of space and time so severe that there is no amount of energy which can safely traverse it. Unfortunately, General Relativity describes in detail what this means for space-time only. What the individual pieces of matter are doing, simply isn't part of the theory. There are some individual constraints applied by relativity, but not enough to answer the fundamental question of what happens to the matter. In practice, when you reach the limits of what GR can describe, you fill in the gaps with Quantum Mechanics. The problem is, at this point, Quantum Mechanics has no expression for mass... what it is, or how it works. Simply put, gravity is just too weak of a force ordinarily for QM to even have to bother to account for, so it has simply not done so. So the point were we would turn to QM for answers, QM has none. What we can say is that curvature of space-time can only be communicated at the speed of light. If the sun were to suddenly vanish, we would continue to orbit where it used to be for 8 minutes until its absence was communicated to us. This fact requires that for a black hole to vanish, all sources of mass within it must be simultaneously destroyed. If however, the mass is contained in a space larger than a single point, this is impossible to achieve... since "simultaneous" is limited by the speed of light which is conveyed less than instantly. The result being, in this case, there is nothing you can add to a black hole to reduce its total mass... outside of Hawking Radiation... which, as I said, I don't get.
mia, what is the relation btw gravity and energy. If E=MC^2 and mass exerts gravitational forces, one would expect energy to exert gravitational forces as well. Also, can gravitons be observed.
Energy and mass are exchangeable, but they do not possess the same properties. Energy does not have mass, mass can't travel at c. Remember, energy is conveyed at the speed of light, and as something which possesses mass gets closer to the speed of light its mass increases. Which is to say, it would take more energy than what is in the universe to accelerate a single massive particle to the speed of light. Gravitons are a theoretical QM gravity boson. They do not exist in relativity. If they do exist at all they could theoretically be observed... but not with the equipment we currently have.
I would think the existence of black holes rather convincingly undermines the concept of a gravity messenger particle (graviton). Think about it, if black holes represent space-time so curved that not even light (which travels at c) can escape... then how would a graviton (which also travels at c) escape? If gravitons couldn't escape, then how is the mass of the black hole conveyed to anything outside of it? If I'm not mistaken, the current QM best guess is the Higgs boson, which communicates mass as attachment to the Higgs Field... a sort of QM version of space-time.
