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juan_rod
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What is Quantum Gravity and the Curvature of Spacetime and how is it all relevant to one another?
Oh, I did not see your most recent post. This is a reply to your original post.juan_rod said:What is Quantum Gravity and the Curvature of Spacetime and how is it all relevant to one another?
If and when someone can do it I suppose they might, but being able to give a correct way to start would mean you knew were you were going.MeJennifer said:Actually how quantum gravity relates to curvature of space-time seems like an interesting question. Is it really impossible to give some overview on the general approach on how to introduce backgound independence into quantum theory?
marcus said:Oh, I did not see your most recent post. This is a reply to your original post.
Juan, the first thing to understand is the classical idea of the curvature of space, from back in 1915 before quantum theory entered the picture
it was Einstein's insight that what we experience as gravity is really geometry, and the Einstein equation of 1915 shows how the distribution of matter determines the shape of space around it-----this is the main equation of Gen Rel
a famous physicist later put that equation into words: "Matter tells spacetime how to curve. Spacetime tells matter how to move."
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starting in 1919 the geometrical theory of gravity (Gen Rel) was tested---repeatedly and with increasing precision. It really does predicts what will happen more accurately than non-geometric theories----theories in which space is a rigid rectilinear framework and gravity is explained by force vectors
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so after 80 years of testing Gen Rel, we pretty much accept that space is a dynamic, changing, active thing-----its shape changes as matter moves around in it.
fortunately it doesn't change very much except for very dense massive things, so we don't notice------it is still approximately the foresquare rigid spacetime that Newton imagined, so for practical purposes we still think of it like that.
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quantum theory comes in when you try to give this dynamic geometry, interacting with matter, a QUANTUM description-----that means using stuff like wave-functions, and having uncertainty built in.
it doesn't mean that space has to be divided up into little bits:rofl:
(sometimes people think space must be made of quanta)
it means that things that you observe and measure about the geometry of space----like SURFACE AREA, and ANGLE, and VOLUME, and even the dimensionality itself-----are no longer fixed definite things but are instead quantum observables (which can incorporate uncertainty)
For example, in a quantum model of a region of spacetime, the curvature is allowed to have some uncertainty---and depend on the quantum state of the system.
that's all I can provide as an introduction. the main thing is to understand the pre-quantum 1915 business first-----when that is assimilated it is easier to think about shifting to a quantum version of it.
juan_rod said:Thank you, this clears up a lot. But how is it all relevant to a black hole and it's properties?
Anonym said:juan_rod:” But how is it all relevant to a black hole and it's properties?”
I have no idea.
Well you seem more advanced than I thought your OP indicated.juan_rod said:Hence my problem... thanks a lot everyone.
With regards to this question I am interested to see what the members here think of integrating quantum theory with the priniciple of general covariance. Is it at all possible or would it indicate a fundamental flaw in at least one of the theories?juan_rod said:What is Quantum Gravity and the Curvature of Spacetime and how is it all relevant to one another?
Anonym said:DocN:” what happens to RT at this singularity?”
I beg your pardon for my ignorance, what RT stands for?
...when I was a student, I attended the seminar given by Y.Zeldovich at Moskow Stecklov Institute. The issue was not a particular problem or particular solution of some problem. Y.Zeldovich presented analysis whether the Einstein GR contains essential singularity. If I understood him correctly, the answer was no.
However, I agree to wait
DocN said:doestn't relativity theory "collapse" at the singularity just like all physics laws?
Doc
DocN said:doestn't relativity theory "collapse" at the singularity just like all physics laws?
Doc
Anonym; And what are substitutions? Hollywood movies? I guess that it is the collapse of wave packet speaking (transition from Quantum world to Classical world: E. Schrödinger Cat). BH out said:My original question consisted of a general and or limited understanding of Quantum physics and the curvature of space-time. now you have introduced electrodynamics, how is this relevant to the properties of a BH?
For the described reasons I consider our debate about BH very interesting but at present status of the theory groundless. I have no required background in gravitation (I did not work in that area of scientific research said:it seems maybe, that i am trying to put things together in my own terms using only limited knowledge. thank you all for your help. Because no one fully understands the properties and the behavioral activity of a BH it seems that one must wait and see what answers comes with time.
Juan_Rod
DocN said:Can one say that at the singularity, we would find such a transition from GR to quantum states? It appears that even the black hole itself is circular in shape--still a classical formation?
I hope you don't mean that "Quantum Gravity" implies making use of gravitons. There are other approaches too, such as described inRandallB said:“Quantum Gravity” - Fundamentally based a quantum approach, utilizing QM (its derivatives or equivalents) and uses the Standard Model including the idea of particle exchange of gravitons (yet to be discovered) to account for gravity.
Blackhaven said:Why does the curvature of spacetime cause matter to experience gravity?
Actually: curvature of worldlines would be better, since curved spacetime is a misnomer.Blackhaven said:Why does the curvature of spacetime cause matter to experience gravity?
A black hole is a region in space where the gravitational pull is so strong that nothing, including light, can escape from it. This happens when a massive star dies and collapses under its own gravity.
Quantum gravity is a theory that attempts to reconcile the principles of general relativity (which explains gravity on a large scale) with those of quantum mechanics (which explains the behavior of particles on a small scale). Black holes are important in the study of quantum gravity because they are regions of extreme gravity, where the effects of both theories are believed to be significant.
The curvature of spacetime is a concept in general relativity that describes how mass and energy can bend the fabric of space and time. This curvature is what causes objects to move towards each other due to the force of gravity.
Black holes have an immense amount of mass and therefore create a significant curvature in spacetime. This curvature becomes infinitely strong at the center of the black hole, known as the singularity.
Currently, we do not have the technology to directly observe the effects of quantum gravity and the curvature of spacetime. However, scientists use mathematical models and observations of black holes and other extreme objects in space to study these phenomena and make predictions about their behavior.