Physics is often considered to be a challenging subject because of mathematics, but the problem with physics is that people have incomplete or wrong ideas that they build their mental models from. Incomplete ideas are made worse when we give students phrasing that allows them to build around incomplete ideas.
There is gravity in space. There is a lot of gravity in space. The International Space Station (ISS) is about 400 km from the surface and the radius of the earth is about 6400 km. The gravitational force is about 90% of what is experienced on the surface of the earth. So when we see astronauts floating in space, it has nothing to do with a change in gravity. You don’t need to change gravity at all to float or experience zero-gravity. You just need to be falling with your container. You can even fly on planes now that drop and allow you to experience zero-gravity as you and the earth plummet towards each other.
My purpose in this post though is not to convince you that there is gravity in space or to explain why it looks like there’s no gravity when there is a lot of it. I want to convince people that the term zero-gravity itself is harmful and it’s past time to stop using it. Understanding how physics works while in orbit is a complicated topic and it should require a lot of thinking and questions for someone to really understand at a deep level. But terms like zero-gravity are misleading and prevent those questions from being asked by people of all ages.
There are two systems in your brain. System 1 does all of the automatic thinking. System 2 is how you learn new things when you learn complex things such as models for physics in orbit. Your system 1 is probably already equipped with phrases and words for you to use when describing space. Phrases like “For every action there is an equal and opposite reaction” and words like “inertia” are ready to be used by system 1 when you are presented with phenomenon about space. So when you see a person floating you might think that since the astronaut isn’t moving towards the floor of the ship that gravity must not be pulling. But that astronaut is accelerating towards the earth, and the earth is accelerating towards the astronaut. You just don’t notice because you’re comparing the astronaut to the ship.
Engaging system 2 thinking is not easy to do. Conflicts can do this sometimes. If I say there is gravity in space and that does not fit into your set of mental models about zero-gravity, you might read carefully looking for evidence or logic to challenge your thinking. This would be system 2 at work, and this system is needed for most people to improve their understanding of orbit. But when we give students terms like zero-gravity it becomes more difficult for them to do this engagement. They have the official term. When we change the term from zero-gravity to microgravity or low gravity that becomes even more entrenched.
We screwed up. We should never have created the term zero-gravity. It aligns with too many misconceptions of motion and the term also limits the ability to engage system 2 thinking. When we changed the term we could have made a new term that would force people to engage with those issues, but instead we chose words that reinforce them. Microgravity is going to help people incorrectly say “well I know there’s some gravity, it’s just barely any gravity” when there is a substantial amount of gravity between the astronauts and the earth.
This issue permeates in science. When we complain about people who do not listen to science such as those that oppose vaccines, climate change deniers or the discrepancies between environmental activism and environmental science, these same issues are at play. People are being given phrasing and terms that prevent them from using logic and evidence to understand the correct science. This is why people think organic means pesticide free when the reality is that organic farming is worse for the environment. But for people to believe that becomes very difficult because of a successful (?) marketing campaign that uses emotion to prevent system 2 thinking. This is why so many anti-science people believe in conspiracy theories where scientists are acting out of financial motivations.
And we push back hard against anti-vaxxers, people fearful of artificial sweeteners and climate change deniers. But maybe we’d be more successful if we could use science like a ship orbiting the earth to teach people how to use system 2 thinking effectively. Maybe then we would be able to bypass these emotional stunts that prevent them from refining their mental models instead of relying on phrases and terms. We could teach how to think in the most non-threatening manners.
Instead many cling to their concepts by using advanced science. I routinely see smart people defend the term zero-gravity. They do this by using systems. You can define a system in the most convenient way. You can say a car that is accelerating uniformly from rest to 40 m/s is not actually accelerating because you can define a frame of reference that has that same acceleration. Because of this people argue that centrifugal force is an actual force because it appears within a rotating frame of reference. And these people are technically right but incredibly misleading and for no gain other than being technically right in an extreme and useless example. It’s time to push people to be educated rather than trying to be right.
I don’t have the reach to replace zero-gravity with something such as notevenclosetozero-zero-gravity or waymorethanzero-zero-gravity. But if you do, or will one day, do something to get people to understand science instead of “learning” terms.
