As you all probably already know I am a huge science geek. So I thought I would take about 2 minutes of your time to share this momentous time in history by explaining some of this theory to you with some easy to understand examples.
What is “General Relativity”? It explains how space time is warped by objects that contain mass and why all objects that have mass in space follow an orbit. Even visible light (massless) is affected by this warping on an extreme scale (black holes)
"Space-time curvature". Licensed under CC BY-SA 3.0 via Commons - https://commons.wikimedia.org/wiki/File:Spacetime_curvature.png#/media/File:Spacetime_curvature.png
As you can see, Space-time fabric is warped and creates a curve around Earth due to its mass. (Yes, it’s not just same made up phrase from “Back to the Future”) This curve is what objects in orbit like the International Space Station, Satellites and even our own planet around the Sun follows. On a much grander scale, our entire solar system orbits the center of mass of our galaxy. Every galaxy orbits around other galaxies and so on.
But some of you may ask, this is just a theory, so how do we know this actually exists???? Simple, SCIENCE!!!!! Scientist have actually tested this theory by performing experiments based on mathematical models of general relativity. One of the most recent was using the Cassini Probe on its way to study Saturn by measuring the time it takes a Radio signal to make the round trip from Earth, to the Probe and back to the Earth.
"Cassini-science-br". Licensed under Public Domain via Commons - https://commons.wikimedia.org/wiki/File:Cassini-science-br.jpg#/media/File:Cassini-science-br.jpg
As you can see in this example, the radio signal gets warped by the orbiting planets and especially by the massive object that is our Sun. This radio signal takes longer to arrive at Earth than it would travel through empty space in a straight because of the warping of space-time, thereby proving the theory. GPS signals are actually delayed as they travel on this curve of space-time, but now we are getting into special relativity, but just take into account, engineers have to adjust the clocks using an algorithm to account for time dilation due to part of general relativity. Otherwise our cars could be off position by as much as ~50 ft per day.
This theory can go on to explain some phenomena in other places of our Cosmos including Red and Blue shifting of light from Stars, Gravitational Waves and Lensing, Black Holes, Tidal affects and even time dilation that affects GPS. But the one we experience every day is the Gravity we feel on Earth. This is because we are inside the gravitational effect/curve of the Earth’s Mass. We don’t ever think about it, because from the day we were born, we have been accustomed to it.
Ok, I’m all done, get back to what you were doing, but I do hope I expanded your scientific insight just a little on this important day in History.