The Four Forces of Nature

The word “force” is used quite a bit these days. A government may threaten the use of force on another nation. A child might scream in protest at being “forced” to clean their room. But, even though we may not automatically think there’s any kind of scientific connection to our everyday use of the word, these real-life examples are very helpful in helping us understand the forces that are unseeable, but always at work.

According to its definition, force is defined as the push or pull upon an object resulting from its interaction with another object. While the forces at play in our world might not be as obvious as one nation retaliating against another when “pushed,” they are still essential for every single aspect of our lives. Without the four fundamental forces of nature, the universe as we know it could simply not exist. But what are these forces, and how are they responsible for everyday life?

Let’s begin with something that is probably already familiar to you: the force of gravity. Before gravity was completely understood, it was thought that planets and stars were purely a creation of a God or some unknown phenomenon, and their movements couldn’t fully be explained. It wasn’t until we got to Galileo that the world really began to question why objects move the way they do. Galileo was the first person to observe that objects thrown from the same height seemed to pick up speed at a constant rate. He also correctly observed that all bodies fall with the same acceleration, as long as air resistance and buoyancy aren’t a factor.

While he was on the right track, it wasn’t until a few decades after Galileo’s death that the theory of gravity was officially presented by Isaac Newton. As the story goes, just a single apple changed the course of science forever… maybe. Newton correctly concluded that gravity was a force that existed between all objects with mass. It pulls objects towards each other, and the more massive the object, the greater the pull. That’s exactly why when we jump into the air, we don’t just leave the planet - the earth is huge, its gravitational pull is too strong for us, keeping us all squarely on the ground.

This is good because… well we aren’t flying away, but when it comes to us actually wanting to leave the planet, well it just sucks, literally. Gravity is the one thing holding us back from easily accessing space. If gravity was just a bit more forgiving, well, we might already be living on the Moon or Mars. Except, we really wouldn’t. We need gravity. Gravity is what keeps the planets orbiting the sun, our moon in orbit around us, but it isn’t exactly what’s holding our galaxy together. There, we venture to dark matter and dark energy. Those are separate videos.

But just note, without gravity, the planets would have wandered off long ago, the sun wouldn’t have heated the earth, and none of us would be living to watch this video. Gravity is still an important area of study today, and more discoveries have been made since Newton. Most notably, Einstein’s discovery that the force of gravity works not only on mass, but on light as well. Of course, this isn’t visible to the naked eye, but it is measurable, and this discovery added valuable knowledge to our understanding of gravity and how it works. General and special relativity… well, we’ll talk about those another time.

But as important as it is, gravity really isn’t that strong. Next to gravity, something called the “weak force” might not sound so impressive, but it’s a force that is even more powerful than gravity, albeit only at very short distances; to be more precise, at the distance of about 0.1 percent of the diameter of a proton. While this distance is obviously not perceptible to humans, it more than does the job. The weak force is an interaction that happens exclusively between subatomic particles. When the weak force is at play, they can exchange three different force carriers, known as bosons. These are essentially tiny little bundles ...