Mar 12, 2024 06:33 PM
https://iai.tv/articles/we-dont-need-a-q..._auid=2020
INTRO: Much of the physics world, and millions in funding, is spent on the ceaseless hunt for a theory of everything which unites general relativity and quantum mechanics. Quantum gravity – a description of gravity that obeys the principles of quantum mechanics – is held up as the holy grail that will lead our discovery, however Isaac Layton argues this search is misguided.
EXCERPTS: . . . The key takeaway from this example is that classical systems can coexist with quantum systems when the classical parts act like they are measuring the quantum ones. Since measurements in quantum mechanics are fundamentally random, this means that any theory describing interacting classical and quantum systems must also be fundamentally random.
The fact that classical and quantum systems can coexist, contrary to early assumptions, implies an alternative to upgrading gravity to a quantum theory: keep gravity classical, but modify it to be random so that it can coexist with existing quantum theories.
[...] The exciting thing about a random classical theory of gravity coupled to quantum matter is that experimental answers may not be too far around the corner. An important feature of these theories is that they inherit the properties of measurement in quantum mechanics, namely that the classical part has random motion, while the quantum part collapses into a definite state, just as the Schrodinger’s cat becomes either alive or dead. It turns out that the rate of these two things are inversely related: the more random the classical motion is, the slower the cat becomes either alive or dead, while the more predictable the classical particle is, the faster the quantum system collapses into a definite state.
This provides a way of testing a stochastic classical theory of gravity. If we experimentally determine that the randomness in the gravitational field is very small, but that quantum systems don’t collapse as fast as expected, we can definitively rule out a classical theory of gravity. Although this may sound bad, ensuring that a theory can be easily falsified is an important feature of any good theory, and distinguishes this proposal for random classical gravity from some of its quantum gravity counterparts.
Before getting too excited and making big claims, it is worth emphasising that there are many theoretical details still to be worked out... (MORE - missing details)
INTRO: Much of the physics world, and millions in funding, is spent on the ceaseless hunt for a theory of everything which unites general relativity and quantum mechanics. Quantum gravity – a description of gravity that obeys the principles of quantum mechanics – is held up as the holy grail that will lead our discovery, however Isaac Layton argues this search is misguided.
EXCERPTS: . . . The key takeaway from this example is that classical systems can coexist with quantum systems when the classical parts act like they are measuring the quantum ones. Since measurements in quantum mechanics are fundamentally random, this means that any theory describing interacting classical and quantum systems must also be fundamentally random.
The fact that classical and quantum systems can coexist, contrary to early assumptions, implies an alternative to upgrading gravity to a quantum theory: keep gravity classical, but modify it to be random so that it can coexist with existing quantum theories.
[...] The exciting thing about a random classical theory of gravity coupled to quantum matter is that experimental answers may not be too far around the corner. An important feature of these theories is that they inherit the properties of measurement in quantum mechanics, namely that the classical part has random motion, while the quantum part collapses into a definite state, just as the Schrodinger’s cat becomes either alive or dead. It turns out that the rate of these two things are inversely related: the more random the classical motion is, the slower the cat becomes either alive or dead, while the more predictable the classical particle is, the faster the quantum system collapses into a definite state.
This provides a way of testing a stochastic classical theory of gravity. If we experimentally determine that the randomness in the gravitational field is very small, but that quantum systems don’t collapse as fast as expected, we can definitively rule out a classical theory of gravity. Although this may sound bad, ensuring that a theory can be easily falsified is an important feature of any good theory, and distinguishes this proposal for random classical gravity from some of its quantum gravity counterparts.
Before getting too excited and making big claims, it is worth emphasising that there are many theoretical details still to be worked out... (MORE - missing details)