Earlier quoted context omitted.
This is the first time i see this word so I'm thankful.
In France we use it in our Math curriculum.
It is probably in math curricula everywhere but not everyone studies math.
An old theory of quantized gravity is gaining new life
51–60 of 69 posts
Re: An old theory of quantized gravity is gaining new life
#52I think the author completely glosses over the fact that Loop Quantum Gravity actually does make predictions, and could provide the explanation for fast radio bursts. Also, the theory is so intuitive and follows such a straightforward logical path from Quantum Mechanics and Relativity, that I would be incredibly surprised if it wasn't the theory closest to actual reality.
By any chance, we’re you ALSO in Carlo Rovelli’s lecture a few days ago? ;)
Re: An old theory of quantized gravity is gaining new life
#53I think the author completely glosses over the fact that Loop Quantum Gravity actually does make predictions, and could provide the explanation for fast radio bursts. Also, the theory is so intuitive and follows such a straightforward logical path from Quantum Mechanics and Relativity, that I would be incredibly surprised if it wasn't the theory closest to actual reality.
By any chance, we’re you ALSO in Carlo Rovelli’s lecture a few days ago? ;)
I've literally watched every lecture he has out there lol :)
Re: An old theory of quantized gravity is gaining new life
#54> 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?
Theoretically, yes. Asymptotically is one of those words that you often read about, but rarely hear in speech. There are plenty of words I come across in text that I understand the meaning of, but often am not familiar with the correct pronunciation as nobody I interact with in daily life use them. I can see this one falling into that category quite easily.
Whether or not the pronunciation is valuable information given that the communication method is again text remains to be seen.
Re: An old theory of quantized gravity is gaining new life
#55> 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?
Theoretically, yes. Asymptotically is one of those words that you often read about, but rarely hear in speech. There are plenty of words I come across in text that I understand the meaning of, but often am not familiar with the correct pronunciation as nobody I interact with in daily life use them. I can see this one falling into that category quite easily. Whether or not the pronunciation is valuable information giv…
Since I finished school, my frequency of hearing that word seems to be asymptotically approaching zero.
Re: An old theory of quantized gravity is gaining new life
#56Earlier quoted context omitted.
There's no particular need for a special explanation of how particle exchange could produce an attractive force: as unlikely as it seems in classicical physics, it's how the forces (electromagnetic) arise in QED. The exchange of virtual photons can transport momentum any way you like.
'Exchange of virtual photons' is a metaphorical expression used to describe artifacts of perturbation theory, it is not necessarily a real process. There is no widely accepted model of what really happens on microscopic scales, we only have equations and those are often replaced by simpler perturbation scheme. So, explanations of attractive force are welcome, Le Sage - type models including.
>There is no widely accepted model of what really happens on microscopic scales,
There's no experimental reason to come up with one - virtual photons work, which means anything else is at this point a matter of philosophy. That's not to cast off philosophy, of course.
Re: An old theory of quantized gravity is gaining new life
#57Earlier quoted context omitted.
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 m…
Are gravitons a thing - i.e.a generally accepted concept in the scientific community? I thought their very existence was highly controversial...
I've always had the naive and hand-wavey understanding that gravity is spacetime, while all the other quantum fields happen in spacetime.
So there may be issues trying to use a particle theory to describe something that may be more fundamental than the other fields.
But IANAP, so this could be completely wrong.
Re: An old theory of quantized gravity is gaining new life
#58> 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?
I was amazed by this too. Why focus on how one pronounces it rather than the mathematical properties of asymptotic behaviour (i.e., that one gradually approaches but never reaches something)?
Yeah, this is a little odd. But in the writer's defense, I read a lot more than I speak, and I often comically mispronounce a useful word when I have to use it in speech, so while I'm familiar with this particular word, I do wish writers would do this with words a little more often than they do.
Re: An old theory of quantized gravity is gaining new life
#59Re: An old theory of quantized gravity is gaining new life
#60Earlier quoted context omitted.
The 'non-kinetic' parts are just geometry, which we already understand and incorporate into general relativity.
Just as there is a huge difference between Maxwell's laws and QED -- the same gap lies with relativity and the graviton. Knowing the gravitational field as full fidelity partial differential equations based on the stress energy tensors is a great achievement. But it alone does not tell the full story as to how that field is mediated. Just as EM is mediated via virtual photons, we wish to know more..
I just want to point out that, in my experience, "alternate theories of gravity" and especially those derived from a kinetic basis, tend to be a field that's extremely ripe with crackpots and pseudo-scientists. This is because what tends to happen is - people take some simple math, low-level enough that they can comprehend it, and apply it to this very intricate reality, hoping to strike gold somehow. The kinetic model is simple enough, and understood well enough that you could use math that's accessible even to those who are not actual scientists. Of course, it's never worked. It's a very, very common scenario.
Be careful.