It took a while 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 then 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 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 are the same regardless of the reference frame, so a ball thrown up in a moving car behaves as in a stationary car, and 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 orbits the sun at about 66,000mph, and the galaxy at an amazing 483,000mph. Our speed relative to the cosmic background radiation is said to be 1,300,000mph, but 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?