For over a century, the two leading theories in physics have had irreconcilable differences, and scientists have scrambled to find ways to square them, to no avail. An experiment proposed in 1957 by American luminary Richard Feynman, is now getting a makeover, and the results could be significant.
Scientists at Oxford University and University College London (UCL), are attempting to overhaul one of the late Nobel Laurette’s experiments and in doing so, hope to heal the rift in a dramatic fashion. Could a Theory of Everything be near? This would be incorporating all four physical forces: gravity, electromagnetism, and the strong and weak nuclear forces, into one solid working theory.
Thus far, theoretical physicist Steven Weinberg, himself a Nobel Laurette, has only been able to combine electromagnetism and the weak nuclear force. A final theory—as Weinberg calls it, would mark the end of physics as we know it. Although the laws of general relativity and quantum mechanics work exceptionally well in their own spheres, some of the rules that govern one area don’t work in the other, and vice-versa. For instance, Relativity explains the gravitational force as it relates to bodies on Earth or in space. But it falls apart on the quantum level.
The current upgrade to Feynman’s proposal focuses on quantum gravity. Two papers on the upcoming experiment were published in the journal Physical Review Letters. In the first researchers write, “Understanding gravity in the framework of quantum mechanics is one of the great challenges in modern physics.” A lot of experiments have been proposed, but it’s proven extremely difficult to test quantum gravity in the lab.
One of the reasons, researchers write in the second paper, “Quantum effects in the gravitational field are exceptionally small, unlike those in the electromagnetic field.” Sougato Bose leads the UCL team. He told Physics World, “For example, even the electrostatic force between two electrons overtakes the gravitational force between two kilogram masses by several orders of magnitude.”
These physicists believe if they can detect gravity on the quantum level, it would help us better understand why it operates so differently there, and perhaps reveal the secret to navigating between our two prevailing theories. Feynman’s idea to test for quantum gravity surrounds something known as superposition. A particle is thought to exist in all possible states or positions at once, until measured. Then you can nail down its exact location (or velocity, but not both).
Feynman speculated that using quantum entanglement, one could take a small mass and place it inside a gravitational field, causing it to become entangled with the field on the quantum level. Then, the physicist would be able to detect the field’s interference, before indicating the mass’s position. The interference itself would cause the mass to take a single, specific location or form, which would occur before the mass separated itself from the field. And so in this way, quantum gravity could be detected.
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