The Fundamentals, Part 1: Gravity

With all the talk happening on PiPT about fictitious motion, antimatter transformations, and overly-complicated analyses of the tides, it’s about time that we went back and explored the bare necessities of the Universe, those few things it absolutely needs to be what it is today. These absolutes are called the fundamental interactions of nature: 

• Gravity
• Electromagnetism
• Strong Force
• Weak Force

They're the four things that keep everything in one piece; without them, nothing, not even atoms, would exist. 

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1. Gravity

Good ol' gravity. It's the force that most of us are probably most familiar with, though it's the weakest of the four by far. Its effects have been known for about as long as humans have been on this Earth, yet it took a long time for someone to truly see it as its own entity. Aristotle was one of the first; he described gravity as the movement of objects to their 'natural place'. Earth went the lowest, water floated on that, air floated on that. Pretty straightforward. 

Luckily, Galileo Galilei debunked this theory. He was the first scientist to try and quantify gravity in any significant way. Besides the alleged ball toss off of the Tower of Pisa, Galileo took observations by rolling balls of different masses down an incline. He discovered (to the angst of several who challenged him) that everything fell at the same rate; no matter how big or small the objects, they all hit the ground simultaneously. 

Galileo's Challengers.

Once Isaac Newton came along and started playing around with the data (creating Calculus, and all that) he found that the force was even more quantifiable than anyone had previously thought. His studies led to the development of whole systems of equations for gravitational attraction, purely based off of the movement of earthly and celestial objects. In fact, his math was so accurate, he was able to postulate the existence of Neptune purely based off an eccentricity in Uranus' orbit. 

Pictured: Uranus with a wobble. 

No one could argue that Newton's ideas of gravity held some serious... weight... in regards to the workings of the Universe. However, there were slight errors between the predicted and real experimental values of several astronomical movements that Newton's theories didn't solve, and several decades passed before a man named Albert Einstein developed a theory sound enough to account for these discrepancies. Einstein's General Theory of Relativity took into account the warping of space-time, and through his detailed analysis of gravity's effects, created the basis of modern astronomical study today.

Gravity is a little unique when compared to the other forces. For one, it has no limit. My mass affects everything in the Universe (though, as was mentioned before, gravity is too weak to actually move any of these bodies). Secondly, there's no way to be repelled by gravity like  the other fundamental interactions can; it attracts, and nothing else. Third, you can't block gravity, or redirect its influence. If something exists, it's gravitationally attracted to everything around it, no questions asked. All of these unique properties lead physicists to one unanswered question: what creates gravity? How does it do what it does? As we'll see in future posts, every other fundamental interaction has a particle associated with it; gravity has no such thing. 

At least, not yet. Many physicists advocate the existence of a 'graviton', the elementary particle of gravitational force, that's responsible for the direct attraction between objects. It would have to be massless, but intricately connected to all masses itself, making the graviton very, very hard to find. Moreover, gravity's effects are negligible in the quantum realm, making attempts to capture the trace of a single graviton even harder. Even mathematically, trying to prove the graviton messes up a physicist's calculations to the point that nothing makes sense anymore. For something so common, and so describable, gravity's reason for existence remains a mystery. 

In the meantime, don't sweat it. Gravity, through its fantastic cosmic influence, still has plenty to offer. 

Standing on the shoulders of giants, we are.