It took time for science to realize that we live in a reality bubble. Maxwell’s equations describe light as a wave so in the nineteenth century, a superfine ether was assumed to propagate it in space. The earth orbits the sun to give the seasons and spins to give night and day, so that ether can’t always be stationary (Figure 5.3). The speed of light should vary as the ether moves – light going against it should go slower, and light going with it should go faster. But in 1887, Michelson and Morley found, to everyone’s surprise, that the speed of light on earth was the same in every direction, so there was no ether wind because the earth’s movement didn’t alter the speed of light.
Then in 1904, Lorentz showed that the speed of light would remain constant if the space and time of all reference frames changed by what became known as the Lorentz transformation. Shortly after, in 1905, Poincare deduced the relativity principle, that the laws of physics stayed the same regardless of how a reference frame moved, so a ball thrown in a moving car behaves the same as in a stationary car. In general, swinging a pendulum or shining a flashlight is the same on a satellite orbiting the earth at thousands of miles per hour as it is on earth.
This is fortunate, because our earth actually is a planetary platform carrying us through the cosmos. Its spin whirls us around at about 1,000mph, it goes around the sun at about 66,000mph, and around the galaxy at an amazing 483,000mph. Our speed relative to the cosmic background radiation is estimated to be 1,300,000mph, yet science still works on earth as it does in the rest of the universe. Einstein then wondered what others didn’t, which is why doesn’t reality change when we move?