Johanluus

yes I have but I am still not clear on some of their their interpretations. To be more specific: Wikipedia's "Classification by Schwarzschild radius:" "if one accumulates matter at normal density (1 g/cm³, for example, the density of water) up to about 150,000,000 times the mass of the Sun, such an accumulation will fall inside its own Schwarzschild radius and thus it would be a supermassive black hole of 150,000,000 solar masses" I can understand why this would happen due to gravity.But why does it end at the Schwarzschild radius. But Calculating force of accelleration just outside the schwarzschild radius of different stellar masses gives enourmous values. Each value differes by many orders of magnitude for different values of M. What is the correlation of the "Schwarzschild radius" and the degeneracy of all matter. And what is the critical factor that determines the raduis. From the formula the Schwarzschild radius is proportional to the mass with a proportionality constant involving the gravitational constant and the speed of light: I do not understand the significance of this radius. To formulate my question better , why would an object need different amounts of energy( using newtons law) to escape a mass inside its "Schwarzschild radius" if the object were just outside the radius? Why is the accelleration different just outside ,but just inside everything breaks down to a singularity.(if that is true)?

"In a typical Type II supernova the newly formed neutron core has an initial temperature of about 100 billion kelvin (100 GK), 6000 times the temperature of the sun's core. A further release of neutrinos carries away much of the thermal energy, allowing a stable neutron star to form (the neutrons would "boil away" if this cooling did not occur)." The above explanation raises further questions for me: Would I be right to deduce that a collapsing typical Type II supernova forms a stable Neutron Star IF the initial mass of the star ~ Chandrasekhar limit. Around 1.4 solar masses. If that is the case what is the critical mass limit required by a star , if it were to collapes into a black hole ? Furthemore what is the final degeneracy force( particle) that we know of that the accelleration would need to overcome(collapse-degenerate)? Finally what would this accelleration be in terms of c? Im not sure if my questions make sense , but there seems to be some fundamental correlations with the Accelleration, mass of star, and Degeneracy Force, to what the star ultimately produces when it 'dies', which I have not yet understood. Can anybody point me into the right direction to get further reading material on these questions?

Agreed there is nothing special about earth.But there is something special about who makes the measurment, because it will differ for different inhertial frames.

"Once you hypothesize a physically impossible situation, you can't draw any valid conclusions" agreed

Yes he can measure his accelleration ,which is the rate of change of velocity . But his velocity ( rate of change of distance) , had to be measured WRT somewhere "local". And only according to that reference frame, he may need infinite energy if he tries to reach c( according to that reference frame). Merged post follows: Consecutive posts merged"Why would it take an infinite amount of mass or energy to push an object a finite speed? That finite speed being 186,000 miles a second." I think the origional question is a very valid one. As far as i can deduce it is a direct result of Einstein's 2nd Postulate 2: The speed of light in a vaccum is completely independent of the motion of the source emitting it. And it is a constant.

yes then i agree we would be able to see it if such an oblect existed, one that could move faster than c , relative to us, and it emitted photons . Providing the space between us and it was static.i.e no expansion. Merged post follows: Consecutive posts mergedyes then i agree , if such a object existed , and it emitted photons. we would see it if the space between us was static. Merged post follows: Consecutive posts mergedwhat would happen if such an object was moving toward you , it would pass you before you "see" it.

"The infinite increase of mass & energy is as seen from Earth, not as lived by the moving object. The astronaut on the spaceship can assume that the Earth is moving at near C speed, not him. Nothing strange happens to the spaceship, and it can increase its speed as the commander wishes without annoyance. But that is not what someone upon Earth will observe: this one will observe that the spaceship will never reach C." My question is this "how does the commander measure his speed" relative to what ... he could theoretically be boosting his rockets and actually slowing down relative to a gravitational accelleration in the opposite direction. so he thinks he's going faster , but he may just be escaping some supermassive black hole ....what as his marker?If we on earth are discussing him we are his marker.. but thats only relative to us?

"I think the above statement is wrong." explain i'm curious?

The way i analize the question is to break it down into events and some statments. 1. A galaxy can't have a velocity greater than C relative to our spot here on earth. This would violate Einstein's Special relativity ( one would need infinite energy to achieve this) from our point of view. 2. The real question IMO is : WHEN that galaxy emitted that photon LONG AGO . If the distance between us and that galaxy was expanding faster than c AT THAT TIME , we would never see it. It is out of our observable horizon or "future". But if the distance WAS expanding at a rate slower than c , then some time in the FUTURE after that event , the photon will eventually reach us , with a redshift relating to the recession speed. WHEN it does eventually hit US ( SAY NOW) , the galaxy will be much further away and the recession speed could NOW be greater than c . In this case we have detected a photon that WAS emitted some time in the past from a galaxy that was receeding at a speed less than c at THAT time. But NOW it is receeding faster than c and any photons emitted NOW will not be seen in our future. What i find amazing is this: If we(hypothetical observer) were hitching a ride on that photon from when it left the galaxy(THEN), to when it hit earth(NOW). We would say that NO time has passed, due to time dilation( I.E the events were spontaneous)! Furthermore the distance we would have travelled would be zero , due to length contraction. All because of relativity. Again it depends on the observers point of view!

thank you martin I believe verilinde is onto something , using the holographic principal and entropy down to the planck area of the event horizon seems to bring out a deeper understanding to me on the "fabric of space" , whether we call it geometry , gravity or whatever .. it is ultimately a form of information i like his comment " gravity is the cost of moving information around" whatever form of information we may choose.

Thank you for all your inputs and viewpoints which I appreciate. I understand the concept of the gravitational field and the metric that defines the distance. This is good.I am not interested in the mathematics however. The way in which I interperated the response from AJB is that , Gravitational field theory is what we currently have to describe our interpretation for "fabric" of space. Hence he's answer "The thing is this metric is time dependant. So the distance between any two points can change with time. This is what we see as an expansion" And obviously many people have the same viewpoint. Quantum Gravitational field theory is one of the great advancements to better describe our classical view of gravity and even space itself. But I am not yet convinced that it is the fundemental principal describing expansion. The one is the canvas and the other, the paint on which this dynamic canvas ,changes. It is the expansion of the former that puzzels me. I chose a hypothetical cubed meter , trying to eliminate any local effects. The reason why I divulged into the wave properties of all photons , is because they seem to have the property to "occupy" all that "space" simoultaneously, since the dawn of radiation.Until something actually interacts with them , collapsing their wavefunction, back down to our reality. All these concepts lead to a deeper understanding of our universe , but it is far from complete. If it was the complete truth we would all agree 100%. Anybodies viewpoint can still be considered as a cheap answer, until then.

Distances must change dynamically according to the law of GR, the einstein field equation. my question was not to describe how interpret the "gravitational field between points or mass " as their position changes. But rather why we believe that our universe , the very fabric of space is expanding , and try and isolate what this dynamic quantity really is.

yes i am Its a facinating experiment , which confirms the wave nature of a photon. But "waving in probability" is a little abstract for me. For me the bright lines on the detector in the experiment illustrates that the photons energy is concentrated there . Whereas the dark patches ( wave cancellation), indicates that the energy is absent there. Why then define a "probability" stating whether it could be there or not! If one photon indeed , went through both slits and interfered with "itself" then its energy has been spread or "smeared out" over an area on the detector. this leads to another puzzel , what exactly difines "ONE PHOTON"

"The photons are "smeared" out all over the place, which means that one photon is at many different places at the same time" And they overlap with eachother?? That is the key to my puzzel. How does one arrive at such a wave function?(many places at the same time). Given only that the photons are "free moving" in a relatively flat 3 dimensional cubic meter of "vacuum" or "field" Are there any good references for us novices , that anybody can suggest. My mathematics is adaquate at best, but my imagination is infinite.

"There are still fields in the "void". This means we may have non-zero energy" This statment implies that "fields" are massless particles( or waves) with energy, i.e bosons ( photons) or force carriers. IF this is so , are they expanding . What determines the boundary in the space they (photons) occupy. If there are many force carriers in the cubic meter what is between the force carriers. My origional question seems to be repeated but instead we are replacing " void" with a "Quantum field theory". i am still puzzelled.

If the void between the filamentary clusters is a "vacuum" as we know it. No particles no energy i.e "absolutely nothing". Except mabey for CBR. And I choose one cubic meter , smack bang in the middle of such a void . What is expandinfg inside of that cubic meter. The concept of an expanding vacuum is puzzeling me, where am i going wrong?

Yes that sounds like a reasonable conclusion thank you for your input

"When more matter is forced into the event horizon than can enter the black hole the run off is twisted by magnetic fields into opposing jets. This is not material from inside the black hole. SMBHs do not recycle matter. This is a misconception that proponents of the steady state theory use (misuse)." This is how i interpret it as well. ajb you have elegantly demonstrated to my inferior brain how to calculate the density of a black hole , using first principals. and i actually understand it. thank you. But in my previous post i mentioned. This is the "average" within the Schwarzschild radius as you noted , but what about the density of the volume of the actual "matter" within the Radius (if one could still call it matter/energy). This matter/energy must occupy SOME volume. An that volume must have an upper limit( with respect to density), to which no more matter/energy can be added. down to plank quantum energy levels. "A kind space with no more space to fit anything". All that happens is that vulume increases , increasing the (SR). Is there no maximum energy density of space? I guess this is my question. comparable to the other extremes absolute temp = 0k; velocity c; remember a black hole by definition , evolves because the volume of the "actual matter" is less than the volume of the Schwarzschild radius(SR) . which would suggest that there is a "layer" within the SR that does not contain matter. Does this sound plausable?

i understand the "concept" of singularity , i just question why they have to exist, even in theory?

" don't know if there is a maximum energy density in space" honest answer! My view on the matter is this. If the singularity did exist within the black hole (which im inclined not to support). Then we cannot put an upper limit for Energy density in space. A singularity IMPLIES , the mass within the supermassive black hole can approach infinity, which in turn implies that there can exist a black hole with a Schwarzschild radius that can also be infinately large).As time tends to infinity everything will become one black hole. Then why have all the galaxies not yet been swollowed up by these singularities. This is not what we observe today. There are galaxies , there are black holes at there centres, all of different sizes, and different stages of their evolution. Some are active and some are dormant. There is a upper limit , which keeps the balance. Just like an electron in the box , if we reduce the size of the potential walls , at some limit the electron cannot exits within its boundaries , due to its wavelength , so it will be ejected. That is my analagy of the upper limit of energy density of space.

thanks for your response. it does shed light. "the average density of a large supermassive black hole is comparable to that of water" This is astounding! This is the "average" within the Schwarzschild radius as you noted , but what about the density of the volume of the actual "matter" within the Radius (if one could still call it matter/energy). This matter/energy must occupy SOME volume. An that volume must have an upper limit, to which no more matter/energy can be added. down to plank quantum energy levels. "A kind space with no more space to fit anything". Is there no maximum energy density of space? I guess this is my question. comparable to the other extremes Absolute zero for temprature ( 0 k). c for velocity.

yes they are "purely theoretical " ?? thats why we speculate?

Hi im Johan and im facinated about cosmology.

I have some questions on black holes. 1. Is there any information regarding the ratio of how much matter/energy supermassive black holes swollow in relation to how much they eject in the form of plasma jets (blasars) or any other radiation. my reason for this question is is related to my next question. 2. Will black holes ever reach a "maximum" filled state where it cannot consume anymore due to space energy density limits , and then only spew out these jets we now observe in blasars. There may be an effective upper boundary ( radius) as to where black holes cannot grow larger. Then they would only serve as catalysts for converting matter to energy and redistrubuting them into the universe for other galaxies and stars to form.