Density of Supermassive Black Holes

day07 · Aug 28, 2005

Greetings, Can, or perhaps 'should,' Supermassive Black Holes be considered differently than Stellar Mass Black Holes? I have read a couple of things that causes me to ask this question.... - I have read recently that the Density of Supermassive BH's is actually less than that of Water because the Radius of the Black Hole increases as its Mass Increases. This confuses me because in what I have read about Hawking Radiation, (if I am correct) it states that the Area of the Event Horizon can never Increase. I am having trouble putting these two concepts together. Do Supermassive Black Holes form a 'Heliopause-type' structure.... If so does this become more Oval in Shape as the Mass of the Black Hole Increases? - Also interesting to me, the Nuker Team's finding that Supermassive Black Holes correspond to 1/2 of 1% Total Galaxy Mass regardless of the Galaxy's Size. This seems inconsistant with the Idea of Supermassive BH's forming through Accretion of Stellar Mass BH's. Is this an explination for the lack of observable 'Intermediate-Sized' BH's ?

nexium · Aug 30, 2005

If the theories are correct, super massive black holes should be considered differently than steller mass black holes, which should be considered differently than mini black holes. It is likely that mini black holes rarely, if ever, ingest mass fast enough to offset the Hawking's radiation, so the event horizon radius decreases. More massive black holes, however, typically gain mass faster than the Hawking's radiation produces mass loss, so the radius of the event horizon increases minutely most days. I can't imagine why the area of the event horizon would not increase if the radius/mass increased. Typically, supermassive blackhole accreation disks produce many millions of times more radiation than the Hawking's radiation from the event horizon, so the total radiation does produce an effect somewhat like a heliopause. My guess is the Hawking's radiation is too puny (except mini black holes) to produce a heliopause without the help of accreation disk radiation. I don't understand why you think oval instead of spherical. Neil

kmarinas86 · Aug 30, 2005

Consider this. As a photon approaches the event horizon it undergoes gravitational time dilation. By the time it reaches the center, the universe would already have gone cold and become no more (according to an accelerating universe). A black hole is more like a snow ball with suspended layers being added on as new matter adheres and hovers above the event horizon. http://www.google.com/search?hl=en&q="infinite+time+dilation"+gravity The proportionality of the Schwarzschild radius to the mass of a black hole is 1.48 E-27 m/Kg. Therefore any mass of particles greater than x(Kg) cannot have a radius of x(1.48 E-27 meters) or less. So a mass greater than 0 must have a radius greater than 0.

beilzabob · Sep 1, 2005

Thank you very much.

nexium · Sep 10, 2005

Steve is doing it again = typing authoratively about the tentative opinions of mainstream science. I think averaging the density inside the Schwartschild radius makes more sence than guessing how many angels (or quarks)can stand on the surface area of the singularity! If zero can stand there, how do infinately long quarks (or anything else) get inside the singularity? Neil

kmarinas86 · Sep 10, 2005

It impossible for a black hole to have infinite density - I think. Infinite time dilation forbids this. The universe, in theory, would be infinity years old by the time a particle reaches the schwarzchild radius, making infinite density impossible. The particle itself experiences "no time" - according to theory. However, we can concieve the following: A small black hole will have a very high density. Infact, the smaller it is, the higher its density. When mass is effectively proportional to radius, then "average" density is inversely proportional to the radius squared. The very center of the black hole (large or small) may have a near-infinite density. The density of within a particular black hole decreases from the center, like how the density of within the sun decreases from the center. The difference is that the very center has a density that approaches infinity.

jatslo · Sep 11, 2005

If the object were headed towards the black hole at velocity of "c", or greater, the event horizon would be located proportionally to its velocity. Gravitational dilation is not a factor unless the "G" forces interact with its inertia. The event horizon could be like the rings on Planet Saturn, except each ring is defined by velocity, inertia, and masses of particular matter.

jatslo · Sep 11, 2005

I really do not see any evidence that would substantiate the affects of gravity on time. I seriously think that space-time is untouchable. There is no evidence outside of fancy mathematics, in which that mathematics is based off of other assumptions, etc.

zarabtul · Sep 11, 2005

Maybe not gravity but Einstein's law could be pretty accurate in terms of time and traversing it... E=MC^2 was an interesting equation to figure from. Has anyone heard anything about the three stars found in I believe 2002 that were collapsing on themselves and were pulling in the surrounding solar system as well. What impact do those events have on us if they have any at all. Are those gravitational pulls any strong than our suns?

Saiph · Sep 11, 2005

Two immediate pieces of evidence: Mercury's orbit is correctly predicted by Einstien's General Relativity. Before that, standard newtonian mechanics was close, but didn't give the exact answer. And as the same mathematics that very accurately predicted mercury's orbit also predict that gravity affects time it's pretty good shot of being true. As a matter of fact, if gravity does not affect time, then GR is wrong, and it's predictions for mercury should be wrong as well. the GPS satellites incorporate GR equations into their electronics to provide their high accuracy measurements. If GR is wrong (a significant portion of these is the gravity effects on time) then the GPS satellites would become increasingly inaccurate over time. So it isn't just fancy math...it's been applied, and predicted observed phenomena. <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>

jatslo · Sep 11, 2005

"Chaos": Gravity effects velocity in which velocity effects time that is observed. GPS will falter; that is why some satellites have maneuverability capabilities. (GR?) General Relativity? General Relativity is partly wrong. Newton was partly right. Where does "Chaos" factor?

Saiph · Sep 11, 2005

GR is general relativity, sorry, I'm too used to that convention. The velocity and gravitational effects are different. They both affect objects. Taking into consideration only one of the two produces erroneous results. GPS faltering will not be able to be corrected by maneuvering the satellites, as it is not a positional problem. It's due to trying to communicate between the GPS satellite due to it's motion and difference in gravity, and hear on the ground. GPS also compensates for their velocity. Now, having GR be wrong, even partly, and newton partly right is an interesting proposition. GR says newton is completely correct as long as you are not at high gravity, high acceleration, or high speeds (I mean really high here btw). It's merely a matter of accuracy. General relativity gives the same answers as newton, as long as you're not going a significant fraction of light speed, and the difference in gravity isn't too high. Even mathematically GR produces newtons laws of motion if you put in low speeds and velocities. For instance, take the mechanics equation for velocity: Newton says: v=at General relativity says: v=at / sqrt(1+a*t/c^2) However, if a is small, say only 10 m/s over 10 seconds: newton says: v = 10 m/s^2 * 10 s = 100 m/s. General relativity says: v = 10 m/s^2 * 10 s / sqrt(1 + 100/ 3x10^16) 100 / 3x10^16 is very small (~1x10^-14, or 0.000000000000001) So 100 m/s / sqrt (1.000000000000001) gives...well, basically 100. mathematically, at low speeds a*t is much less than c^2, as such that term can be dropped from the general relativity equation since it produces a value so close to zero. General relativity at low speeds now says: v=at / sqrt(1+0) After simplifying it produces v=at/sqrt(1) = at. The same as Newton. <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>

jatslo · Sep 11, 2005

"Maneuverability Capabilities": Right, hardware, software maneuverability. The rest is interesting too; however, this anology is based off of assumptions that may or may not be right, so the chaos predictability or unpredictability could be off, right?

kmarinas86 · Sep 11, 2005

Gravitational Time Dilation: T=1/(1-2GM/Rc²)1/2 Velocity Time Dilation: t=1/(1-v²/c²)1/2 Velocity in Circular Orbit†= Sqrt( Acceleration * Turning Radius ) GM/R²=A GM/R=AR GM/R=V² 2GM/R=2V² V=velocity required at altitude to maintain circular orbit v=actual velocity of spacecraft Combined Time Dilation: Tt=1/[(1-v²/c²)(1-2V²/c²)]1/2 Tt=1/[1-2V²/c²-v²/c²+2V²v²/c4]1/2 Tt=1/[1-(2V²+v²)/c²+2V²v²/c4]1/2 if V=v Tt=1/[1-3(v/c)²+2(v/c)4]1/2 † For circular orbits A=4pi²R/Period² Period * (v)elocity = (C)ircumference = 2piR C²/R=4pi²R C/v=Period A=(C²/R)/(C/v)² A=v²/R AR=v²/safety_wrapper>

Saiph · Sep 11, 2005

actually, these calculations are based off of two assumptions which have never been comprimised: The speed of light is constant, and observed by everyone to be the same in all frames of reference. That the effects of gravity and acceleration are indistinguishable, and therefore gravity and acceleration are equivelant. That's it. <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>

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