Nature Quote by Richard P. Feynman

Quantum mechanics as it stands would be perfect if we didn’t have the quantum-gravity issue and a few other very deep fundamental problems.

— Gerard 't Hooft

From a theoretical point of view, it is very hard to imagine how gravity could avoid being quantized.

— Alan Guth

The quest for a quantum gravity is one of the greatest unsolved problems in all of science.

— Michio Kaku

We're going to need a definitive quantum theory of gravity, which is part of a grand unified theory - it's the main missing piece.

— Kip Thorne

“So, in the end, the most improbable and hence the most puzzling aspect of space is its very existence. The simple fact that we…

— Lee Smolin

“Now, at the outset of the twenty-first century, we stand on the verge of a new revolution. The search for a deeper theory than…

— Marcus Chown

I am not aware of any sensible theory of how classical gravity could interact with quantum matter, and I can't imagine how such a…

— Alan Guth

“Problem 1: Combine general relativity and quantum theory into a single theory that can claim to be the complete theory of nature. This is…

— Lee Smolin

“The key question for a quantum theory of gravity is then the following: Can we extend to quantum theory the principle that space has…

— Lee Smolin

“I think that the obscurity of the theory is not the fault of quantum mechanics but is rather due to the limited capacity of…

— Carlo Rovelli

“The unsolved problems of the physical world now seem even more formidable than those solved in the twentieth century. Though in application it works…

— Gerald Holton

“The only ‘failure’ of quantum theory is its inability to provide a natural framework for our prejudices.”1”

— Matthieu Ricard