General relativity and quantum mechanics are two of the most successful theories in modern physics, but they are fundamentally incompatible. This is because general relativity describes the behavior of gravity on a large scale, while quantum mechanics explains the behavior of particles on a small scale. Attempts to combine the two theories, such as string theory, have been made but have not yet been proven to be successful.
General relativity is a theory of gravity that explains the behavior of objects in a curved spacetime, while special relativity is a theory of spacetime and the relationship between energy, mass, and velocity. Special relativity only applies in a flat, unchanging universe, while general relativity accounts for the effects of gravity and curvature on spacetime.
According to general relativity, massive objects can cause a distortion in spacetime, creating a "gravitational well." If the object is dense enough, the escape velocity at the event horizon (the point of no return) would be greater than the speed of light. This means that even light cannot escape, making the object invisible and giving it the characteristics of a black hole.
General relativity predicts that time is relative, meaning it can pass at different rates depending on the gravitational field and relative motion. This is known as time dilation. As objects move closer to a massive object, time will appear to slow down due to the strong gravitational pull. This has been proven through experiments and is a crucial aspect of general relativity.
Yes, general relativity has been extensively tested and proven through various experiments and observations. Some of the most famous confirmations of general relativity include the bending of light near massive objects, the precession of Mercury's orbit, and the detection of gravitational waves. While it is not a complete theory and may be modified in the future, general relativity has been shown to accurately describe the behavior of gravity in our universe.