In my last three posts (which have conveniently been combined onto a single page in the tabs), I proposed three tests which anyone with modest resources could perform to show whether or not the Earth is flat. But lately I've been wondering if there is a similarly simple experiment that would show that the Earth is turning.
Not that a moving Earth and a sphere Earth are the same issue; educated people knew that the world was spherical long before they could tell if it moved or not. Some early thinkers, most notably Aristarchus, argued for a heliocentric model thousands of years ago, but it wasn't until the time of Copernicus and Galileo that we started having observation evidence to back it up.
Now, of course, we have lots of evidence; our entire space program depends heavily on the motion of our world and all of our solar neighbors. But flat-Earthers don't believe in any of that.
What I'm more concerned with is thinking of a way that, without the observational skills of an astronomer or sophisticated and expensive equipment, an average person could conduct a test to show that the Earth is turning.
I know of one that I find convincing, involving the Coriolis Effect. These synchronized videos show the experiment. I had another thought, but there is a problem that I'm not sure how to get around.
First, the idea. What if two people, one living very far north or south of the equator, and the other at the equator, were to weigh a standard reference weight at their respective latitudes using an accurate (but inexpensive) jeweler's scale? The precision of the scale is enough to show the difference due to gravity as long as the weight has enough mass.
Let's say that the reference weight is 100 grams. In theory, at either pole the reference weight would weigh 100 grams, and at the equator it would weight about 99.7 grams. That would show that some force is counteracting gravity at the equator. Maybe the flat-Earthers would make something up, but it seems obvious to me that the counteracting force is centrifugal (yes, I know, it's a pseudo-force, but it ACTS like a force, and shows that movement is taking place).
But there is one problem I do not have enough knowledge to overcome: calibration of the scales. When you buy a precision scale, the first thing you normally do is calibrate the scale to a reference weight just like the one I'm talking about. But, of course, when you calibrate the scale, you'd be calibrating it to local gravity, and the comparison would be invalid.
So my question to anyone who understands scales very well is this: why do you calibrate the scale? Is it because no two are exactly the same? Is it because something happens during shipping? Or is it, in fact, because of local gravity? Do you see a way around my little problem?
I'd love to hear from someone with the necessary expertise, because if this could be done with a pair of inexpensive jeweler's scales and reference weights, I think it would make a good addition to the everyman-approach to first-hand knowledge of the shape and motion of the world we live on.
Please leave comments below; I'm truly interested in hearing your thoughts on this.