- #1
pellman
- 684
- 5
Why should the action be Lorentz invariant? Every time I come across this it is assumed by the author without qualification. As too obvious to explain maybe? Ain't obvious to me.
Lorentz invariance is important in physics because it is a fundamental principle of special relativity. It states that the laws of physics should remain the same for all observers in uniform motion, regardless of their relative velocities. This allows for a consistent and unified understanding of space and time, and is essential for many modern theories and experiments in physics.
There is a significant amount of experimental evidence that supports Lorentz invariance. For example, the famous Michelson-Morley experiment in 1887 showed that the speed of light is constant and independent of the observer's frame of reference. This is a key tenet of Lorentz invariance. Additionally, many other experiments in particle physics, cosmology, and gravitational waves have consistently confirmed the principle of Lorentz invariance.
Lorentz invariance is closely tied to the concept of spacetime, which combines the three dimensions of space with the dimension of time. The principle of Lorentz invariance ensures that the laws of physics remain the same in all frames of reference, regardless of their relative motion. This allows for the consistent use of spacetime as a unified framework for understanding the universe.
While Lorentz invariance has been extensively tested and confirmed, there are some theories that suggest it may be violated in certain extreme conditions, such as at the Planck scale or in the presence of very strong gravitational fields. However, these violations have not yet been observed, and Lorentz invariance remains a fundamental principle in modern physics.
Lorentz invariance is essential for our understanding of time and space. It allows us to reconcile the seemingly different concepts of time and space, and to understand them as interconnected dimensions in the fabric of spacetime. Lorentz invariance also helps to explain the observed phenomena of time dilation and length contraction, which have been confirmed through experiments and are integral to modern theories such as special relativity.