Quantum wavelength of gravity

[south]

TL;DR

I put the question here because I don't know where the best place is. If it is misplaced, I beg your pardon and correction.

Quantized phenomena operate with a determined or determinable wavelength. My question refers to the quantization of gravity.

Does it make sense to ask what the quantum wavelength of gravitation is? If it does make sense, is an explicit and quantitative determination possible?

 

[anuttarasammyak]

Gravitational wave was observed in 2016 as predicted by GR. But quantum plays no role there.

 

[south]

Thanks for answer.
1. How can I find an article referring to the observation made in 2016?
2. Should I discard the idea of quantum gravity?

 

[phinds]

2. Should I discard the idea of quantum gravity?

Well, there's a Nobel Prize in it for you if you can figure out a valid theory of Quantum Gravity.

 

[phinds]

. How can I find an article referring to the observation made in 2016?

Google "LIGO"

 

[south]

Thanks phinds.

1. I deduce from this that there is nothing quantum in gravity, nor can there be anything quantum as long as the standard model remains in force.
2. Why then is there this urgency to achieve a quantum theory of gravity?

 

[FactChecker]

2. Why then is there this urgency to achieve a quantum theory of gravity?

Quantum Theory and Relativity are the two main theories of modern physics, and they are not entirely compatible where they are simultaneously relevant. Finding a consistent theory combining the two is the "holy grail" of modern physics.

 

[Ibix]

I deduce from this that there is nothing quantum in gravity,

Not quite. We have never detected any quantum effects of gravity, but we don't expect them to be visible in the experiments we can do at the moment so this is no great surprise.

nor can there be anything quantum as long as the standard model remains in force.

No. It is true that the standard model of particle physics does not include gravity, but this is just because we don't knowhow it fits in. A working theory of quantum gravity would be expected to extend the standard model to include it.

Why then is there this urgency to achieve a quantum theory of gravity?

I don't think there is any urgency in the sense that it would solve any immediate practical problems. In the sense that everybody wants to be first to do it, maybe.

We need a theory of gravity that can deal with quantum sources of gravity and doesn't break down in extremely strong fields. That's the obvious hole in our fundamental physics knowledge, which is why people are interested in it.

 

[Nugatory]

Why then is there this urgency to achieve a quantum theory of gravity?

It's not so much urgent as it is important, perhaps the single most important unanswered question around these days. Quantum mechanics is a powerful and successful theory that works really well everywhere except in the presence of extreme gravitational affects; general relativity is a powerful and successful theory that works really well everywhere except in the presence of extreme quantum affects; but neither works well when both gravitational and quantum effects are involved. That's a frustrating hole in both theories and suggests that we will learn something amazing about both gravity and quantum physics when we find a theory that fills that hole.

 

[hutchphd]

I would say it is compelling. We have seen wonders emerge from the other great unifications of physical understanding: the theory of electro-magnetism being perhaps the most astonishingly fecund. What marvels may be lurking just behind this veil?

.

 

[south]

It's not so much urgent as it is important, perhaps the single most important unanswered question around these days. Quantum mechanics is a powerful and successful theory that works really well everywhere except in the presence of extreme gravitational affects; general relativity is a powerful and successful theory that works really well everywhere except in the presence of extreme quantum affects; but neither works well when both gravitational and quantum effects are involved. That's a frustrating hole in both theories and suggests that we will learn something amazing about both gravity and quantum physics when we find a theory that fills that hole.

Thanks Nugatory. I liked what you expressed regarding urgency vs. importance.---------Of all the details in physics to snoop around, I had the bad luck of choosing one like this. Next time I'll try another one. Kind regards.

 

[south]

The conversation has become extensive and I want to thank those who have helped me so far:

anuttarasammyak,
phinds,
FactChecker,
Ibix,
Nugatory,
hutchphd

Thanks to each and every one of you. Happy New Year.