It's All Relative. Really.

In the wonderful world of Physics, everything can be categorized with four adjectives: big, small, fast, slow.

Physics is pretty much like Sesame
Street, in that sense.

Seriously, though, these qualifiers are what physicists focus on when evaluating anything. In fact, there’s a branch of physics for each combination, and unbeknownst to you (or perhaps fully beknownst), we’ve already covered a lot of these concepts ourselves:

Slow and Big:	Classical Physics (The Tides, Gravity)
Slow and Small:	Quantum Mechanics (Quantum Dots)
Fast and Big:	General Relativity (Time Travel)
Fast and Small:	Quantum Field Theory (Higgs Boson)

The fascinating thing is that one man almost single-handedly made all of these possible: Albert Einstein. In 1905, Einstein published a set of papers establishing his ideas on Special Relativity, considered by far the most groundbreaking theory in modern physics. They revolutionized the way scientists thought of the Universe, and made further developments in both science and technology possible. This is all great news, and I’m sure you’re jumping out of your chair with joy, but… what did his papers actually say? What makes Special Relativity so special?

Nope. 

There are two main ideas to Einstein’s theory of relativity. The first is that the laws of physics are the same in any inertial frame, i.e. from a point of view that isn’t accelerating. No matter where you are, the physics never changes. In other words, there is never an absolute frame of reference from which everything measured is more correct than anywhere else; it’s all relative to the observer.

His second, and more counter-intuitive point, is that light is the fastest thing in the universe, no matter what kind of frame of reference you’re in. This can be a bit tough to wrap your head around; no matter how fast you’re going, light always appears to go the same speed c (that is, 299,792,458 m/s).

Though the scientific community was a little surprised at this notion, there was quick acceptance. Many experiments in the years leading up to Einstein’s paper had tried to prove the existence of an otherworldly ether that controlled the speed of light, but test after test only proved that, well, there was no such thing. When Einstein published his conclusion about the constancy of light, there was minimal disagreement.

The Physical Society of London got a little whimsical
with their review letters.

This brings us to the most famous equation in Physics: E = mc^2. In Newtonian mechanics (that is, big things that go slow), energy and momentum are two totally separate things; though there are equations that relate them, the entities themselves aren’t the same due to the distinction between space and time. However, Einstein formulated his theories so that space and time were unified, a.k.a. spacetime. The mathematics of the derivation is a bit complicated, but using spacetime allowed him to prove that the energy of a particle and its momentum were intricately related on a relativistic scale. His resulting equation, 

Newtonian Mass = Energy divided by the Speed of Light squared

…gave mathematical life to his theory.

The thing that makes Einstein’s theory of Special Relativity so amazing is the sheer number of ‘paradoxes’ that come out of it. Depending on how close to the speed of light you are, time can slow, your body can shrink, and even your mass can increase until it’s nearly infinite. Because of Relativity’s speed-of-light restriction and the relation between energy and mass, everything gathering speed tends to compensate through different physical shifts. That being said, only the fastest moving objects can feel these kinds of shifts in any dramatic way; in a normal situation, the relativistic time shift is a fraction of a fraction of a nanosecond, and the change in length is virtually nil.

Going close to the speed of light is kind of like changing time
zones, except not at all. 

With the properties outlined above, Einstein paved the way for the study of modern physics. Everything in a modern physics textbook can be described using his equations… well, almost everything. Once things get too small and transfer into the quantum sciences, Einstein’s theories begin to get a little shaky. In fact, this discrepancy between fields is the fundamental problem in Physics today. Laboratories all around the world are searching as we speak for a way to unify Physics into one grand theory; it’s one of the most important undertakings of our time. If teams like CERN actually end up finding the missing pieces, like the Higgs Boson and the graviton, we may find ourselves in a bona fide scientific renaissance, the likes of which would hold amazing potential for science as a whole. But, until then…

There's really not much else to do.