[3]Before there was relativity, there were absolutes.

[4]Aristotle, Greek philosopher and all-around badass, believed the natural state of an object was absolute rest.  [5]This jived with the universally held belief that the Earth was the center of the universe, which stayed at rest while every other heavenly body rotated it.

This belief lasted for roughly 1800 years.  It had the benefit of being both supported by the Church and being incredibly flattering to us Earthlings.

[6/7]But in 1543, Copernicus risks heresy and ridicule by suggesting that the earth itself is revolving, along with the other planets, around the sun.

 [8]Enter Galileo, who builds the first telescope and makes observations that are consistent with the Copernican model. [9]Galileo also disproves Aristotle’s belief that heavier objects will fall with greater speed by allegedly dropping two balls of unequal weight off the Leaning Tower of Pisa, proving that Galileo was more likely what we would call “book smart” rather than “street smart”.  [10] But notice that when those balls fall on those unfortunate people below, they do so at the same time.  This disproved the Aristotelian belief that objects would be forced to fall at various rates depending on their mass. 

[11]Newton compounds upon Galileo’s measurements, and forms the theory that the natural state of motion is uniform – an object in motion stays in motion – and that forces cause changes in motion.  Even more importantly, Newton’s laws of motion don’t favor a particular place or context – you can expect the laws of motion to work anywhere you go.  [12]Take the common example of a ping-pong game being played on a train.  To the players on the train, the ball moves less than three feet between bounces – [13]but to an observer outside the train, the ball moves forty feet.  Position becomes relative to the observer.

[14/15]We’ve just disproven absolute space. We’re halfway there.

Let’s talk lightwaves for a second.

[16]Meet Danish astronomer Ole Christensen Roemer, who discovers the speed of light in 1676 [17]by realizing that the orbits of the Jovian moons varied depending on where Earth was in its orbit.  His theory was that the light from the moons was taking longer to reach us. Pretty good guess, Roemer.[18]

[18.5]So we’ve established a constant speed for light – but relative to what? [19]Ocean waves move through the medium of water; [20]sound waves move through the medium of air.  Scientists believed, therefore, that there must be a medium that light waves move through – [21]and they came up with a substance they called the ether.  Yes, the ether.  I know.

Except there was one problem – no experiments and no twisting of mathematics could detect the existence of any ether.  The speed of light appeared to just be a constant, which threw a giant monkeywrench into the works for about eighteen years. Science was stumped.  [22/23]Enter our hero, Albert Einstein, who pointed out that the idea of ether was unnecessary (and let’s be honest, a little Twilight Zone-y) as long as we were willing to abandon the idea of absolute time.

[24]The core idea behind the theory of relativity is simply this: The laws of science should be the same for all freely moving observers, no matter what their speed.  The “laws of science” now includes the constant speed of light.

That sounds pretty reasonable, right?  But the ramifications of this simple, elegant idea can quickly become brain-explodingly weird.

[25]Two identical twins synchronize [26]identical Swatches.  [27]One twin boards a spaceship that will [28]travel near the speed of light, while the other [29]goes to have a pint and watch the game at the neighborhood pub.  When Twin #1 returns from his trip, a few weeks later, he finds his brother years older.  This is because, to the traveling twin, the trip has taken less time since he was moving at almost the speed of light.

The theory of relativity throws out the idea of absolute space and absolute time, and instead creates a new object referred to as space-time.  Time now becomes a fourth dimension, a way to measure distance and find your way through the universe.