# 12 Beyond Fascinating Facts About The Theory Of Relativity

People love to drop Albert Einstein's theory of relativity into conversation, whether they're discussing the latest Hollywood blockbuster or just trying to look smart. But what is the theory of relativity? You may know that it involves gravity pulling objects and some possible time dilation, but probably don't know that it is a whole new way of describing reality itself. You may take for granted that you have to meet a friend for breakfast at your favorite place at ten in the morning, but without the forces outlined in the general theory of relativity you would meet at a completely different place at a different time.

First published in 1915, Einstein's theory of relativity managed to solve problems physicists and astronomers had been grappling with for centuries. It's revealed secrets about black holes, planetary orbits, and space travel. And as you learn more facts about the theory of relativity and spacetime, you'll discover just how mind-blowing it is.

In 1905, Einstein published his theory of special relativity, which proved to be a pretty big deal in the mathematics and physics communities. The basic theory states that the laws of physics are exactly the same between objects moving at the same speed. The key is that those objects can't be accelerating - they have to be at a constant speed. It also states that despite your acceleration or speed, the speed of light in a vacuum is the same for everyone.

For ten years after creating the theory of special relativity, Einstein worked to add acceleration into the mix. He had determined that the laws of physics (as in, space and time) were the same for two people moving at the same constant speed. The minute one starts accelerating, however, then you run into problems. The faster you accelerate, the more of a time difference you'll have when observing occurrences with others at different speeds.

In 1911, Einstein created the "equivalence principle," which essentially states that gravity from the mass of an object or from the acceleration of a vessel are the same effect.

If you've ever wondered why a space shuttle launch is so hard on the astronauts, it's because the constant acceleration needed to break the Earth's gravity actually imposes gravitational forces on the people inside the craft. G-Force Centrifuge training prepares astronauts for the effects of that force on their bodies.

In order for all these theories to work, the Universe has to be measured in a different way. Standard X and Y coordinates describe a position in a two-dimensional plane, but because the Universe is a three-dimensional space, a Z coordinate is needed as well. But there's actually a fourth dimension at play in reality: time. "Spacetime" refers to this fusing of time and three dimensional space, and it gave physicists a whole new perspective on understanding the Universe.