Has anyone (sane) ever theorized that the ripples in spacetime in some cases may have existed before the masses of particles (ie. planets / stars) arrived at those locations?
An old theory of quantized gravity is gaining new life
21–30 of 69 posts
Re: An old theory of quantized gravity is gaining new life
#22I'm not sure I see any real change in the status of asymptotic safety. It's a hypothesis. Proving it directly is next to impossible. (Except in spacetime dimension Also, it's unwarranted hype to call asymptotic safety 'an old theory of everything'. It's explicitly not a theory of everything. It's only about gravity. Couple it to the Standard Model, and you still have a theory which breaks down at the hypercharge and Higgs Landau poles.
Re: An old theory of quantized gravity is gaining new life
#23> " In other words, gravity would be asymptotically safe if the theory at high energies remains equally well behaved as the theory at low energies. In and of itself, this is not much of an insight. The insight comes from realizing that this good behavior does not necessarily contradict what we already know about the theory at low energies (from the early works of DeWitt and Feynman). " But what are the actual expecte…
You would observe the theory not blowing up. :) The key feature she never names is known as a "UV fixed point". UV = UltraViolet, which in this context simply stands for "high energy". Fixed point... for that you need to know that the effective values of coupling "constants" aren't actually constant in quantum field theory; they depend on the interaction energy (i.e. how hard you bang your particles together). So the…
This helps, but doesn't say what the theory says gravity will do at higher energy levels.
To me it seems to imply gravity will get weaker at higher energies? Something about that makes me feel like it violates conservation of energy, so maybe that's not it.
Re: An old theory of quantized gravity is gaining new life
#24[deleted]
Re: An old theory of quantized gravity is gaining new life
#25> The theory called asymptotically (as-em-TOT-ick-lee) safe gravity was proposed in 1978 by Steven Weinberg. Would a person interested in an article about quantum gravity not be familiar with the term asymptotically?
Maybe author hears it mispronounced often and it bugs him.
Re: An old theory of quantized gravity is gaining new life
#26Gravity is measurement of the distortion of space, caused by mass. It is an emergent property. The more massive something is, the more its gravity will distort the space around it. So, a small piece of rock that you can hold in your hand, will cause a gravitational ripple in the space surrounding it. This is similar to how the Earth causes a gravitational ripple in the space around it, and it keeps us grounded to the…
From a physics perspective, the many-world, as ridiculous as it sounds, is a more sound theory (believed to be correct by some top physicists) than negative gravity. The explanation of why gravity is only positive is a complex one, but physicists believe it's almost axiomatic. This doesn't mean that you can't have repulsive type of effects, similar to one of the contributions that's believed to make the universe expa…
> The explanation of why gravity is only positive is a complex one, but physicists believe it's almost axiomatic
Isn't that a consequence of relativity, the speed of light being constant by definition? I'm not sure that makes any sense, though, what is the physical unit of gravity N? Jf you mean classical mechanics, than there has to be a negative counterforce by the three axioms of newtonian mechanics and it's just a question of frame of reference.
BTW: Stress on ax-iomatic, as in axis?!
Re: An old theory of quantized gravity is gaining new life
#27Earlier quoted context omitted.
Moreover knowing the pronunciation doesn't give you any help if you don't know the meaning.
That bothered me as well (pronouncing rather than defining)
Particularly as the pronunciation is strange. Strange place to break syllables, and I'm not sure the second vowel is a 'e' in most pronunciations.
/a-sim-TOT-i-klee/
Re: An old theory of quantized gravity is gaining new life
#28I think it is relevant to consider gravity from a more abstract standpoint as well by looking at Le Sage's theory and particularly Hyugens' comments. [1] Whether gravity is mediated by a graviton, and the intricacies that QM brings to bear, one interesting idea I took from the above hundreds of years of thought on the subject -- gravity may be a pushing force mediated by constant spherical wave emission (quantized as…
Dumb question: how do you exchange gravitons with a black hole?
Re: An old theory of quantized gravity is gaining new life
#29Earlier quoted context omitted.
You would observe the theory not blowing up. :) The key feature she never names is known as a "UV fixed point". UV = UltraViolet, which in this context simply stands for "high energy". Fixed point... for that you need to know that the effective values of coupling "constants" aren't actually constant in quantum field theory; they depend on the interaction energy (i.e. how hard you bang your particles together). So the…
This helps, but doesn't say what the theory says gravity will do at higher energy levels. To me it seems to imply gravity will get weaker at higher energies? Something about that makes me feel like it violates conservation of energy, so maybe that's not it.
Also begs the question of how that reaction could even take place if gravitons are totally unreactive with anything other than their source - mass. How would you accelerate a graviton. Gravitons always move at C just like light. Do we have any idea what kind of production and annihalation products will give us gravitons?
Just a guess - dark matter/energy might be the only way to create a graviton without associated mass generating it. That is..the pair production of a virtual dark photon and a graviton.
In that case what are our options?
Re: An old theory of quantized gravity is gaining new life
#30Gravity is measurement of the distortion of space, caused by mass. It is an emergent property. The more massive something is, the more its gravity will distort the space around it. So, a small piece of rock that you can hold in your hand, will cause a gravitational ripple in the space surrounding it. This is similar to how the Earth causes a gravitational ripple in the space around it, and it keeps us grounded to the…
The trouble with this is that an electric field causes exactly the same observed effects on an oppositely charged particle.
Why would an electric field cause this by one mechanism, and gravity by another, when the observed effect is identical?
> then I wonder if we can create a counter gravity
You can not create counter gravity any more than you can create counter electric field. What you can do is move two charges apart.
To do that with gravity you would have to find a way to make double the gravity in one place, and negative gravity in the other, and then separate them.
(Creating counter/negative gravity directly would violate conservation of energy.)