scotmon Posted March 24, 2014 Share Posted March 24, 2014 1. lets take first things first... there is no real proof the there is such a thing as a black hole. 2. fact...we know from observation that all matter is attracted to all matter... 3. fact...we know that the larger the mass of matter is the greater its pull of gravity... 4. fact...when a mass of matter has a gravitational of pull more than the speed of light...it can not emit any light or reflect any light... 5. fact...it has became a ball of gravitational mass...a black hole... 6. fact...nothing can escape from this condition of matter...nothing means nothing no light no radiation no matter no anything... no one has any idea as to how much pressure that a mass of matter can build up. it may be that there is a limit it may reach and it would explode...if this the is the case...this may be where dark matter comes from...and what generates dark energy...since energy cannot be destroyed it would surely spread an enormous amount of energy into the universe...such an explosion may not be observable...i don't know...it appears that such an explosion has yet to be observed... Link to comment Share on other sites More sharing options...
Dissily Mordentroge Posted March 25, 2014 Share Posted March 25, 2014 At this point I suggest it would be a good idea if we all arrived at an agreed definition of 'fact'. 1 Link to comment Share on other sites More sharing options...
Strange Posted March 25, 2014 Share Posted March 25, 2014 1. lets take first things first... there is no real proof the there is such a thing as a black hole. There are, however, a lot of observations that are consistent with black holes. Which is how science works, not by proof or declaring things to be "fact". 2. fact...we know from observation that all matter is attracted to all matter... And don't forget the role of energy. And pressure. And momentum flow. And ... 4. fact...when a mass of matter has a gravitational of pull more than the speed of light...it can not emit any light or reflect any light... Gravitational pull can be described in terms of a force or an acceleration. Would you like to explain what a "pull more than the speed of light" is ? no one has any idea as to how much pressure that a mass of matter can build up. it may be that there is a limit it may reach and it would explode... Actually, we have very good, well-tested theories of gravity which tell us what will happen. So saying that "no one has any ideas" is rather inaccurate. There is no reason to believe there is any such limit or that there will be an explosion. Note that scientific theories make quantitative predictions, rather than the sort of vague assertions here. Also, scientists know the limits of their models and would never declare anything as "fact". Link to comment Share on other sites More sharing options...
imatfaal Posted March 25, 2014 Share Posted March 25, 2014 \snipped as all agreed... Actually, we have very good, well-tested theories of gravity which tell us what will happen. So saying that "no one has any ideas" is rather inaccurate. There is no reason to believe there is any such limit or that there will be an explosion. Note that scientific theories make quantitative predictions, rather than the sort of vague assertions here. Also, scientists know the limits of their models and would never declare anything as "fact". Do we really have theories that tell us what happens that we are happy with? GR predicts a singularity - and even Penrose and Hawking who first did the maths would tell you that an actual physical singularity is very very unlikely. On a cosmological scale we are happy - there is an object with certain astronomical characteristics we can use, but what happens to the matter is still completely open. We are pretty sure it doesn't explode as suggested by the OP - but other than that... Everyone thinks that quantum theory of gravity will provide an answer -but we do not know what that is yet. We have shown how action of neutron degeneracy under extreme pressure will lead to a neutron star for those stars with a mass between chandrasekhar and tolman-oppenheimer-volkoff limits - but we really have no idea what happens to the matter of stars over the T-O-V limit Link to comment Share on other sites More sharing options...
Dissily Mordentroge Posted March 25, 2014 Share Posted March 25, 2014 . . . . . . . . .stars with a mass between chandrasekhar and tolman-oppenheimer-volkoff limits - . . . . . . . . . Without resorting to equations, can anyone please give a brief description of what these limits consist of and why it's thought they apply. Thanks. Link to comment Share on other sites More sharing options...
ajb Posted March 25, 2014 Share Posted March 25, 2014 Chandrasekhar limit is the maximum mass that a stable white dwarf star can have. It is due to the electron degeneracy pressure (due to the exclusion principal) not being able to cancel the tendency of the star to collapse under its own gravity past a certain mass. The Tolman–Oppenheimer–Volkoff limit is almost the same thing, but now for neutron stars. Link to comment Share on other sites More sharing options...
imatfaal Posted March 25, 2014 Share Posted March 25, 2014 Without resorting to equations, can anyone please give a brief description of what these limits consist of and why it's thought they apply. Thanks. A star (non-main sequence) with a mass below the Chandrasekhar limit will most likely finish its life quietly as a white dwarf and then as it runs out of fuel just slow down till it starts cooling. It is held apart (note not held together - gravity holds it together) by electron degeneracy - this is a state in which pressure causes the electrons to be stripped from the nuclei; you end up with positive nuclei in a sea of free floating electrons. This is a fairly stable limit as the Pauli exclusion principle stops electrons from sharing lower energy states - they are all as low as possible. But if the mass is greater than the Chandrasehkar limit then electron degeneracy pressure is not enough to withstand the inward pull of gravity and a new form of degenerate matter is created that is even denser. That is neutron degenerate matter in which the electrons are "forced" to combine with protons to form neutrons. Again no two neutrons can share the same state so there is an outward pressure resisting the now huge gravity inwards. Above the T-O-V limit we know that even neutron degeneracy will not hold against gravity and something else happens - it is at this point we have guesswork of quark degeneracy (a sea of mixed quarks and gluons) or prion degeneracy (not sure) Main sequence White Dwarf Electron Degeneracy Neutron Degeneracy Link to comment Share on other sites More sharing options...
Dissily Mordentroge Posted March 25, 2014 Share Posted March 25, 2014 Chandrasekhar limit is the maximum mass that a stable white dwarf star can have. It is due to the electron degeneracy pressure (due to the exclusion principal) not being able to cancel the tendency of the star to collapse under its own gravity past a certain mass. The Tolman–Oppenheimer–Volkoff limit is almost the same thing, but now for neutron stars. Is this idea obtained from astronomical observation, theory, experiment or maybe all three? Link to comment Share on other sites More sharing options...
imatfaal Posted March 25, 2014 Share Posted March 25, 2014 Is this idea obtained from astronomical observation, theory, experiment or maybe all three? Theory http://en.wikipedia.org/wiki/Tolman%E2%80%93Oppenheimer%E2%80%93Volkoff_equation Link to comment Share on other sites More sharing options...
Strange Posted March 25, 2014 Share Posted March 25, 2014 Do we really have theories that tell us what happens that we are happy with? Not really. Which is why I include the last point about knowing the limitations of our models. Even when it comes to the limits, in general, we know what they are. So neither "no one knows" or "fact" are useful descriptions of scientific knowledge. Link to comment Share on other sites More sharing options...
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