The Big Picture: A 4D Slinky
Gravity and light form a slinky in four dimensions (one for time, three for space).
- A slinky wobbles.
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The Earth has wobbled around the Sun 4 billion times.
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Light is caused by electrons wobbling.
Want a description of all the interactions in a volume (called a Lagrange
density) that can be used to create 4 differential equations (a 4D wave
equation). The solutions to those equations must then be linked to the simple
harmonic oscillations displayed by gravitational and electronic systems.
Thought experiment: slow neutrinos could wobble through the Earth act as a SHO, cycling to the other side of the Earth and back every 88 minutes. This is a longitudinal wave, because the acceleration is in the direction of the velocity.
Slide 39 likes his cocoa frozen.