The Trouble with Gravity: Why Can't Quantum Mechanics explain it?

This video, titled "The Trouble with Gravity: Why Can't Quantum Mechanics Explain It?" was published by Arvin Ash on October 7, 2022, and discusses the challenges of explaining gravity within the framework of quantum mechanics. The video explores why gravity cannot be modeled by quantum mechanics and why quantizing gravity is so challenging. In a classical world, if we knew the position and velocity of all particles, we could predict the future and the past. However, quantum mechanics shows that reality is probabilistic. The exact location of a particle cannot be predicted in advance, even in theory. Quantum fields are the most accurate theory we have and can explain all the forces of nature except for gravity. General relativity is very accurate, so why do we need to quantize gravity? Because general relativity breaks down at quantum scales. A photon or electron, like any other quantum particle, must have a gravitational effect because that's what general relativity says. But if it's a wave before an interaction and can be anywhere until the moment we measure it, where is its gravitational effect located? General relativity can't tell us where. We don't know how this works because we don't have a quantum description of gravity. One reason for this problem is that gravity is not a fundamental force, but rather the curvature of spacetime itself. This means it cannot be described as a quantum particle or field. This makes quantizing gravity extremely difficult. There have been many attempts to develop a quantum theory of gravity, but none have been entirely successful yet. Two quantum gravity theories that have attracted the most attention are Loop Quantum Gravity and String Theory. Loop Quantum Gravity describes spacetime as a network of loops. These loops carry energy and information that result in gravity. String Theory describes reality as a network of strings vibrating in multiple dimensions. One of these strings could be the graviton, a particle that carries gravity. Quantum gravity theory remains an unsolved challenge in physics. It's an important goal because it could provide new insights into the true nature of the universe.