could a black hole?

bjdfit · Mar 30, 2005

could a black hole accrete enough mass to eclipse it's event horizon? or is a black hole constantly expanding? do objects in a black hole radiate toward the event horizon, including gravitons?, making the event horizon's energy and mass equal to the energy and mass acting on it from within and outside?

CalliArcale · Mar 30, 2005

The event horizon is actually an altitude at which the escape velocity is equal to c (the speed of light). In other words, if you had a circular orbit around the black hole at that altitude, it would not be physically possible to escape. You would be trapped. As a black hole accretes mass, its gravitational force increases proportionally (since gravitational force is a factor of how massive an object is). As this happens, the event horizon moves further out. This is not dependent on anything outside the black hole; it is entirely dependent on the mass of the black hole itself. <div class="Discussion_UserSignature"> "People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff." -- The Tenth Doctor, "Blink" </div>

aaron38 · Mar 30, 2005

You're thinking of the event horizon as a physical object, which it is not. While it is a very real boundary, the point of no return, there is no more a physical event horizon than there is a line painted on the earth at the equator. With a very large black hole, a space ship could easily cross the event horizon with no ill effects, that is tidal forces would not shred the ship. But the ship is now trapped near the bottom of the gravity well and can never escape. To answer your questions: 1) No. The EH is defined to be the outer boundary of the black hole and is always outside the singularity. 2) No. A black hole only expands if mass is falling into it. If it stops feeding, it actually begins to evaporate, according to theory. 3) I don't know what the gravitons do inside the event horizon, but the EH has no mass or energy.

jindivik · Mar 31, 2005

<blockquote>In reply to:<hr />2) No. A black hole only expands if mass is falling into it. If it stops feeding, it actually begins to evaporate, according to theory. <hr /></blockquote> i know nothing of black holes, but if it evaporates, will it keep evaporating until it disappears? or leave behind an object which doesnt have enough gravity to attract more mass?

yruc · Mar 31, 2005

http://www.hawking.org.uk/info/iindex.html Professor Hawking one of my personal heros had this to say about black holes.. At the GR17 conference in Dublin, Professor Hawking gave a controversial lecture on his new calculations regarding Black Hole Information Loss. Press Release: One of the most intriguing problems in theoretical physics has been solved by Professor Stephen Hawking of the University of Cambridge. He presented his findings at GR17, an International Conference in Dublin, on Wednesday 21 July. Black holes are often thought of as being regions of space into which matter and energy can fall, and disappear forever. In 1974, Stephen Hawking discovered that when one fused the ideas of quantum mechanics with those of general relativity, it was no longer true that black holes were completely black. They emitted radiation, now known as Hawking radiation. This radiation carried energy away from the black hole which meant that the black hole would gradually shrink and then disappear in a final explosive outburst. These ideas led to a fundamental difficulty, the information paradox, the resolution of which is to be revealed in Dublin. The basic problem is that black holes, as well as eating matter, also appear to eat quantum mechanical information. Yet the most fundamental laws of physics demand that this information be preserved as the universe evolves. The information paradox was explored and formalised by Hawking in 1975. Since then, many have tried to find a solution. Whilst most physicists think that there must be a resolution of the paradox, nobody has really produced a believable explanation. In fact, seven years ago the issue prompted Hawking, together with Kip Thorne of Caltech, to make a wager against John Preskill also of Caltech, that the information swallowed by black holes could never be recovered. On Wednesday, Hawking conceded that he has

geos · Mar 31, 2005

Nonsense. "Condensed Matter" i.e. white dwarfs, neutron stars, magnetars and black holes DO NOT EXIST!! Electric forces would rip apart them way before they would ever exist. Why not look to Electricty - it is only a billion times more powerful than "gravity"

tap_sa · Mar 31, 2005

*COUGH*kook*COUGH*

geos · Mar 31, 2005

show us more Xrays Plasma I don't see Condensed Matter

geos · Mar 31, 2005

Etched Mars Grooves such as these appear etched into the surface of Mars. Although their sizes vary enormously, their outstanding features are the same: parallel, steep sides, often scalloped; flat bottoms; sharp intersections that leave each groove undisturbed by the other; flat terraces; sudden terminations that sometimes skip over intervening terrain, leaving "land-locked" basins; and everywhere an absence of the debris that familiar erosional processes should leave. The grooves indicate a removal of material by forces unknown to planetary geologists. But a force familiar to plasma physicists etches grooves with these exact characteristics: Electrical arc machining. The electrical forces constrain the arc to contact the surface at a 90-degree angle. Because the arc typically consists of one or more pairs of channels that rotate around a common axis, a stationary arc will etch a circular crater. Most of the etched material is lifted from the surface, and the material around the edge is pinched up into a sharp rim. If the rotating channels are sufficiently far apart, they may leave a "peak" of undisturbed material in the center of the crater. Fluctuations in the current may cause variations in the depth and diameter of etching, leaving terraces along the walls. If the arc travels across the surface, it will etch away material to a uniform depth and leave a groove with parallel sides exactly the width of the arc's rotation. Uneven movement may result in a series of overlapping circular craters, producing scalloped edges, or a jumping of the arc, producing linear chains of craters. When a traveling arc crosses the groove etched by a previous arc, it will be unaffected by the change in terrain. Sometimes a "ghost" of the earlier groove will be preserved as the later arc etches its uniform depth down one side and up the other. (An example of such "ghosting" can be seen at upper right in the image.) In a process similar to the jumping that pr

alokmohan · Mar 31, 2005

Geos you are interesting.

yevaud · Mar 31, 2005

Jindvik: Yes, a Black Hole can "evaporate." Steven Hawking stated the mechanism, which appears as "Hawking Radiation." This is where there is a net output of energy *from* a Black Hole that, according to earlier theories, shouldn't, couldn't happen. There's the creation of particle/anti-particle pairs, way down at the level of the Quantum "Foam," which you may also have heard of as "ZPE" (Zero Point Energy), also known as the zero-point field. Normally, they appear, and then annihilate themselves in an instant. But Hawking showed how they could literally "bleed off" energy from a singularity. If one of these pairs appears right on the edge of the event horizon, there's a finite probability that instead of annihilating each other, one member of the pair would be captured, and the other could escape. Thus the appearance of an energy output from something that shouldn't *have* an output of energy! (this doesn't count things such as infalling matter, which heat through friction, and emit high-energy gammas, x-rays, etc. Different mechanism). As well, it is possible for the escaping member of the pair to gain some energy in the process. If this happens enough times, over a very long period of time (hundreds of millions of years at least), enough energy could be drawn from a black hole to take it under the mass/energy limit to even *exist* as a black hole. At that point, according to theory, it would simply "detach" from our space/time continuum. In short, it would just vanish, never to be seen again. Hope that answers your question. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

Saiph · Mar 31, 2005

actually, if the object is electrically neutral, the electrical forces won't rip it apart. They would, however, actually help support such an object...which is what happens (sort of, it also has to do with quantum states) in a white dwarf. White dwarfs have been imaged, and detected. Neutron Stars have been imaed, and detected. Plenty of indirect evidence of black holes exist. Such things as stars orbiting nothing, incredibly small (though massive)gravitational sources have been detected. Black holes exist buddy. Or how else do you explain shoving several billion solar masses into a region no more than light hours in diameter? Electricity may be much more powerful than gravity, but it can also be negated by the presence of charges, as it is both attractive and repulsive. Not only that, but becuase clumps of opposite charges form due to electricity, it weakens itself (as it accretes more of the charge it's attracting, then the net charge decreases, and the net force decreases). Gravity, on the other hand, is only attractive, and so as it gains more mass, it gains more gravity. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

tap_sa · Mar 31, 2005

I experience trouble understanding Hawkings radiation. More precisely why the particle-antiparticle always causes the blackhole to loose mass while rest of the universe grows. I've read that when the particles get separated for good because of the event horizon, the one that loiters outside black hole becomes real while for some reason the one falling into black hole has negative mass/energy. Can't it be ever the other way around, normal particle falls in and some peculiar negative mass particle gets stuck in the rest of the universe? Another question, if we have a black hole with mass M and we throw M amount of antimatter to it, would it annihilate everything inside the black hole and cause a big boom containing 2*M worth of energy?

Saiph · Mar 31, 2005

The loss of mass of the black hole doesn't really have to do with the type of particle dragged in. If they dragged in an anti-particle, that still has the same amount of energy (even if it annihilates in the center) and energy has gravity too.. Where the mass loss occurs is in overcomming the "binding" energy of the two particles. The two particles are attracted to eachother, and by dragging them apart the BH expends energy. This would be recaptured if it absorbed both particles. But if one gets away...then that binding energy is lost to the BH, and it's more than the mass of the particle it gained. Essentially the BH just emitted a particle (matter or anti-matter, doesn't matter) and lost mass. Another way of looking at it is the Heisenberg Uncertainty principle. Basically, it says you can do anything you want, so long as you do it fast enough that no one catches you doing it. It allows particles, for an exceedingly short period of time, to exceed C (of course they also speed a lot of time under their detected speed). This alone allows some particles to escape. This is the weak "hand wavy" answer btw. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

yevaud · Mar 31, 2005

Oh. Beat me to it. Heh. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

Saiph · Mar 31, 2005

nyeh nyeh! :::sticks tongue out::: <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

tap_sa · Mar 31, 2005

Thanks to both of you. I had false impression the the separation of the pair was 'free beer', like just a matter of one of them wandering too close to the event horizon.

yevaud · Mar 31, 2005

No, not at all. ZPE is a continual process, everywhere. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

Saiph · Mar 31, 2005

Well, that's what allows the BH to split them (one is closer than the other, and crossed the event horizon, the other didn't). But yeah, I see what you mean. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

nexium · Apr 1, 2005

All are considering mainstream ideas except Geo. Some of the Geo ideas are left over from the 19th century, which does not necessarily make them wrong. It is thought that the mass loss per second from black holes is approximately independent of the mass of the black hole. That means the lowest mass black holes (if any) lose most of their mass in a nanosecond, but the large and medium mass black holes can easily eat enough to stay ahead of the evaporation. If we ever have the oportunity to get close to small black hole we will likely find that it is evaporating equal amounts of antimatter and matter, or perhaps the evaporation is mostly photons. The gravity gradiant just outside the event horizon of a small black hole is so extreme, energy/mass conversions occur, so we may not be able to determine the form of the evaporation. Clearly large and medium size black holes recapture much of that which evaporated, if they have a dense accreation disk. Please comment, refute, and/or embellish. Neil

Saiph · Apr 1, 2005

actually the evaporation of a BH is linked to it's radius, which is linked to the mass. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

geos · Apr 1, 2005

Note that the so-called condesed matter refer to areas where the Z-pinch effect has created areas where strong radiation is occurring. That proves there is strong radiation - nothing else!! This is from a Plasma Physict (Thornhill) The Electric Universe accepts the plasma cosmology version of star formation, which postulates that a star is formed in a “z-pinch” in a galactic electric discharge. It is a model that can be shown experimentally to work. In contrast, the gravity cosmology version, which postulates that a star is formed by the collapse of a cloud of gas, cannot be demonstrated experimentally nor can a collapsing cloud be identified observationally. Furthermore, this “nebular theory” is beset with theoretical contradictions of angular momentum and magnetic field distribution.

geos · Apr 1, 2005

We see electricty in atoms and plasma but the condensed matter folks have stars "collapsing" into Neutral bodies!! Thornhill and I have very different models. Stars are Anodes. That is why there are so few neurtrinos streaming from the Sun.

yevaud · Apr 2, 2005

Pardon me, but you are blithering nonsense. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

Saiph · Apr 4, 2005

Geos, care to discuss this in my "Electric Sun, energy and alternative models" thread? http://uplink.space.com/showflat.php?Cat=&Board=sciastro&Number=181568&page=1&view=collapsed&sb=5&o=0&fpart= I'd be more than happy to discuss it there (don't worry, I don't bite). <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

could a black hole?

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