Curiosity About Gravity

Written by Jamie Fall

Gravity Is Mysterious

I've been reading about gravity, and I was surprised about how much I did not know. Perhaps you will be just as surprised as I was about some of these gravity facts as I was. Some I don't completely understand, but I will share with you my basic understanding in the hopes it will inspire you to learn more from other sources.

Why Do Astronauts Float?

Do you know why astronauts float around in space, like those on the International Space Station or in a rocket ship? Most people assume it is because there is no gravity in space (that's what I had thought too!), but actually, this is not the case. The space station and all the rocket launches since Apollo are still close enough to Earth that they retain 90% of their gravity. They are only 200 miles up. The reason why these astronauts can "float around" has nothing to do with them being in space; it is actually because they are orbiting Earth (rotating around it). This flying around the planet puts them in a perfect balance between the gravity pulling them to Earth and the rocket's speed pushing them around it (17 thousand mph). This seems to create a sort of constant free fall so that people float around in the space station. Because there is a perfect balance between push and pull against and of gravity on their bodies, they don't fall to the Earth. To me, this is very hard to intuitively grasp because I would assume the rocket would fall still since gravity is a constant pull on it. Or, at the very least, I would assume they would be pressed against the back of the ship from the constant flying forward. But in actuality, they float around exactly as if there were zero gravity. And the space station doesn't even need to use its thrusters to stay in orbit. The only reason they need to fly so high up before going into orbit is that the air is too thick in the atmosphere, whereas up so high, it is very thin, so there is no air resistance. An interesting thought scenario from this is that if you had a planet with no atmosphere and was perfectly smooth, then you could theoretically fly a space station in orbit that was only a few feet off the ground. You could float around in the station. Of course, it would need to be going 17 thousand mph. 

The Earth's Gravity On The Moon

So, this floating effect is only apparent when you are in orbit rotating around Earth. But if you stopped orbiting and instead went outwards, you would stop floating. So, the astronauts on their way to the Moon could not float around until they got far enough away from Earth to not be affected by Earth's gravity. How long would this take? Well, farther than the space station, but not as far as you might think; only going 200 miles up, their gravity is reduced by 10%. That shows you just how quickly the force of gravity weakens as you travel away from Earth's surface. At about halfway to the Moon, the gravity effect on the astronauts is 1 part of 1000. So 1/1000 percent. Basically zero. At this point, they could float around freely. By the time they reach the Moon, it is even less. Very very near zero percent. At this far away, with the gravity being so low, you might wonder how the Moon is able to stay in orbit around Earth? After all, a body in motion, such as the Moon, wants to continue in the direction it's going. It takes force to change it. Having it instead curve around Earth takes a great deal of force from Earth's gravity. But out this far, the gravity is super weak, so how does it do it? You might suggest that the larger size of the Moon would cause it to affect it differently, but from what I have read, this doesn't seem to be the case. All objects are affected equally by gravity regardless of size (feather and a rock fall at the same speed in a vacuum). 

The answer is I don't really know. I believe it may have something to do with relativity and spacetime or the motion of orbits that I don't understand. Or maybe it doesn't take much force to move the Moon around the Earth. So, for now, it's a bit of a mystery to me how the Moon is pulled around the planet when the gravity is so weak at this distance. But I will study it more; I'm sure there is an answer.

Why Don't We Fall Into The Sun?

It turns out the reason we don't fall into the Sun is the same reason the space station doesn't fall back to Earth, which is because we are in a perfectly balanced orbit. It is something of a miracle that the other planets do not affect our gravity enough to disrupt our perfect orbit, especially for over 6 billion rotations. It shows you how perfectly placed they must have been. You might expect our trajectory to be a perfect circle around the Sun to keep such a stable orbit, but in actuality, it is an elliptical orbit. As the Earth approaches the Sun it speeds up, and then as it approaches the farthest point away from the Sun, it slows down. You don't feel this change in speed because the Earth is so big that you won't notice it, but it does affect the length of the day by a few seconds. If you were like me, you might assume this would be what causes the seasons (when we are closer or farther from the Sun), but surprisingly it does not affect our seasons. In fact, the Earth is closest to the Sun during January, and farthest from the Sun during July (opposite of what you might expect!), and the seasons are actually entirely from the tilt of the Earth facing the Sun more or less.  

The Wall To Truly Understanding Scientific Fundamentals

The more I learn about gravity and our solar system, the more I am surprised to learn things that I thought I understood but never actually really thought about. The solar system is truly more mysterious and surprising than I ever thought possible. I would encourage everyone to learn more about these things, and I believe you too will be surprised. One difficulty I do find is if you dig deep into science questions, you will eventually hit the "math wall" as I call it. These being mathematical equations that you won't understand. And even if you can solve them, they don't really make intuitive sense (for me, anyway) for explaining things. I took math in college but to understand the equations for any real fundamental problem (how gravity works, how atoms work, how light works, etc.), you will always eventually come to mathematics that is so beyond your skill level that they basically will force you to give up genuinely questioning further. I'm more of a visual learner. I wish there were a way to visually represent these complex equations in a visual simulation of sorts. If there truly is no way to explain the fundamentals simpler, I feel like 99.9 percent of people are doomed to just trust that someone smarter than them understands the fundamentals of the Universe and just hope they are right. Of course, the common argument is that they've created such incredible technology based on these equations and physics (that most of us will never truly understand) that they must be right. And smart people I think I trust to tell us the math works. But it still leaves us rather separated, I feel. I hate to compare science to religion, but it almost feels like the theory of gravity is written in Latin, and only the priest can interpret the holy book of laws for the common folk. It's probably not so purposefully nefarious, but there is a similar disconnect between scientists and the common people, especially nowadays with the rise of conspiracy theorists distrusting everything the mainstream tells them. I admit that I am not great at math, and this feeling of "them" hiding knowledge is probably just a natural frustration of not understanding the complexities. 

Compromise Of Understanding 

Maybe there's a compromise here that could help bridge the gap between scientists and people who do not necessarily have a traditional background in science or mathematics but are equally curious about understanding and questioning the Universe. Maybe scientists could start publishing two versions of their papers; one version that is the normal scientific paper, complicated and full of equations that other scientists could check in the standard peer-reviewed process, and a second that is a layman's simplified explanation paper for the general public to read over. I know they already have simplified explanations for these theories. Still, these are usually done after they are (supposedly) proven, sort of as a way to inform us on what they already decided. But I would like the simplified paper to be about trying to prove the theory, to us, the general public. This way, it would let the individual people try to decide if it seems correct or not as well. I know it may not be possible for everything, but I think it would be a step in the right direction. There may even be some real benefit to trying to simplify your theory down to its basics. Maybe people in other professions may even make some insightful comments! Perhaps an artist would have a unique interpretation of string theory. Or a surfer would have an insight into quantum mechanics that most physicists never considered (this actually happened). I don't mean to dilute the integrity of highly trained physicists or mathematicians.

I think it's just sometimes they can get stuck in their own bubble of understanding things and don't consider other ways of viewing the world. Math is a cool way of explaining the world, but what about music? Or art? Or psychology? Could you explain the Universe through these lenses? Everyone should be welcome to contribute to these great theories of explaining the Universe. I know for me personally if they are deciding great fundamentals of how the world works for all of humanity, like that we are all vibrating strings, or that time goes backward as you speed up, or things can be in two places at the same time, or how gravity works, I just would like to be more part of the discussion!

About the author: 

I'm Jamie Fall. I'm from the US. I studied fine arts in college and went back later for my teaching degree. I teach Art in China to elementary and high school students. My goal is to help my students learn to express their natural creativity and learn that they can use this creative ability to change the world positively.

I'm also an artist myself, working in various mediums, including oil paints, watercolor, digital, and others. I also enjoy game design and stories. I believe you can create art through any medium that expresses yourself creatively. For me, often, the ideas behind the art are the most important part. I've always been interested in spirituality and philosophy, as well as science and fictional stories. Oftentimes my art reflects these ideas in abstract ways. More recently, I've tried to do more formal writing on some of these ideas. I don't claim to be an expert on most of the spiritual or scientific topics I write about. Rather, I consider them more of a creative exercise in thinking. Like a journey through ideas and wondering that hopefully leads us closer to the truth. I hope you can find some inspiration in my thoughts that helps you on your own spiritual journey.