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The Egyptians and Mesopotamians thought the sky was a fixed dome, not a rotating one. The heavenly bodies were in the fabric or body of the dome but their motion did not come from the motion of the dome. They moved about inside it. The sun and moon traveled over the earth and then under it or...

There were steps between the Ptolemaic model and the modern heliocentric model. -The Copernican heliocentric model placed all 5 known planets in circular orbits around the sun while retaining epicycles and deferents. [Still quite flawed.] -The rival Tychonic system placed the earth at the...

I've made some changes.

It confuses people who: -struggle with expanding a concept -have difficulty dealing with metaphors and analogies -are overly-literal -have poor spatial reasoning Especially a group that is aggressive, engages in motivated thinking and rationalization, and unconsciously places themselves in a...

This is such a tricky question. One that can't be answered yes or no. I think I'll soon have time to expand on something I've already written in another thread. We have to talk about intuitive thinking, self-deception, aggression, rationalization, gas-lighting... I think we can all agree...

Yes, that's exactly it. Thanks for starting this thread, as I've been "meaning to do" for a long time. Procrastination. A standard argument (chestnut) you see about the ISS goes something like this: They say the ISS is about the size of a 747. How small is a 747 at 30,000 feet? But they...

I can see how a builder would think that way. For our purposes, no. For our purposes, the only measurement is in degrees. The measurement in degrees doesn't change, so the error doesn't change. You've got to stop thinking as a builder, and start thinking as a navigator/astronomer/geodesist...

I'm just the most amateur of amateur astronomers and only know the basics. I think where you're getting confused is in scale. A brick wall that's out of level by 18 inches would be a horrible bit of work. But think about scale. Eighteen inches across three miles is a tiny error in proportion.

The DIY theodolite described in this thread is a relative of the astrolabe, the theodolite and the sextant. They all measure in degrees. Yes, there's an error involved, but it's a DIY device. The error isn't very large. What Mick was trying to do here is give FE Believers a tool and method...

A vintage theodolite used in geodetic surveying. The wheels are marked in degrees. Is this what you would consider the third point for reference?

You've returned to talking about seeing a distance in feet. Use our spirit level to set up a sheet of (darkly tinted) plate glass on saw horses perfectly level, i.e. perpendicular to the way a plumb bob would hang. If you put a marble on the sheet of glass, the marble would not roll. There's...

FE Believers would resolve the problem by claiming some unknown newly discovered optical phenomenon is causing an illusion that the water level in the tubes appears to be higher than the ocean horizon level. But of course it's not, because water can't bend. And no one has seen the curve...

Example of a glider falling straight down... slowly. It doesn't have to fall nose down. I anticipate the objection that it isn't following the earth's surface - if it were following the earth's curvature it would have to nose down. But that's not true. On any part of the earth's surface...

Yes. I deleted that part, because it was getting too complicated. I really should learn to delete the whole post when I'm doing complicated re-re-edits, then just do a new post; so that people don't catch me with my pants down like this.

This is the way I think of it. There are people here much more knowledgeable in physics than I am, so I welcome corrections. In the case of the plane traveling around the globe: If it is flying level, it's actually falling straight down at the same time... slowly. At exactly the rate the...

That's not really the issue. My advice to you is to start with the basics and educate yourself to think in terms of kinetic energy and potential energy in general, and then kinetic energy and gravitational potential energy. Every object that gains altitude uses kinetic energy to do so, and...

Yes, I think this is very much the way he pictures things. Down is an immutable direction. Level is immutable. A plane surface. If he took it this far, he might think of this as a kind of reductio ad absurdum.

I was confused by Wallace's description. I had to reread it. But before that I thought you'd been confused by where the line of sight through the telescope would be, so it's lucky I deleted that before you caught me.

You caught me before my editing, and re-re-editing, was done.

(I've done some editing here.) I think I see what your reasoning is, now. The calico sheet was three feet high, and the center of the black band was probably in the center of the sheet as a whole, but how thick (vertically) was the black stripe? If it were one foot, which seems logical when...