Over the past few weeks, we’ve been talking about the standard model of particle physics. When we finished talking about the particles included in that model, it may have seemed like the standard model was completed, and we had nothing more to talk about on that subject. Yet, that is very incorrect. The standard model is not just an explanation of the different particles that make up our universe. Instead, it is an explanation of the interactions that exist at a subatomic level. This means that, to truly understand and talk about the current version of the Standard Model, we need to talk about quite a few more things. I am beyond excited by that fact, because it means that I get to share my knowledge with you! Our next 4 part series will be about one of my favorite pieces of quantum mechanics: The Fundamental Interaction. So sit back, relax, and enjoy Part 5 of Unlocking the Secrets of The Standard Model: Gravitation.
Before we can begin to understand the secrets behind gravity, or any of the fundamental forces, we must first understand the parent term “Fundamental Interaction.” A fundamental interaction is defined as “an interaction that cannot be reduced to more basic interactions.” Simply put, a fundamental interaction is an interaction between matter that cannot be broken down any further than itself. There are 4 fundamental interactions that we know of, each of which serving a niche, yet imperative purpose to our universe. These 4 forces are gravitation, electromagnetism, the strong nuclear force, and the weak nuclear force. During this series, we will be talking about these forces in the order that they were discovered, or proven. Today’s topic is the first of them: gravitation.
Gravity is a complex subject. When I say complex, I mean COMPLEX. We have known about Gravity for hundreds of years, yet we still have barely a rough theory as to why it exists. This theory is the ever famous Theory of General Relativity, proposed by one of the greatest scientific minds in human history: Albert Einstein. Einstein theorized that gravity was caused not by a particle, but instead by the interaction between mass and something called spacetime. Spacetime is a theorized type of matter that permeates the universe. An example of how spacetime works would be to think of it like a house. If all of the matter in the universe were the different parts of a house, spacetime would be the concrete foundation that it was built upon. It exists everywhere that matter does. According to Einstein, spacetime was a fluid substance, capable of being manipulated and warped. He theorized that objects with enormous masses, stars for example, had the ability to cause spacetime to warp in a strange way, therefore causing it to attempt to pull things towards it. According to general relativity, the sun only has gravity because it warps the spacetime around it, causing things to be pulled towards it.
Gravity is an extremely strange concept for one specific reason: it is the only fundamental interaction that does not have a particle to carry its force. Every other fundamental interaction has some sort of force carrying particle, which allows it to exert its influence over other matter. Yet gravity has no known particle, instead being caused by the interaction of theoretical spacetime, which is also not a particle. In an effort to rectify this issue, many particle accelerators have begun the search for the particle that is now being called the “graviton.” Though it has yet to be discovered, many theorists are positive that it exists. Despite the incredible strength of gravity, it is actually the weakest of the fundamental forces. It exerts the least force per area compared to all of the other particles.
Well, that’s it for this post! Catch you guys later!