So, some people might be wondering, what was the gyroscope question about? And why was it swiftly followed by another post on relativity?
Good questions! In my meanderings across the internet, I occasionally stumble upon strange things and stranger people. Most recently, I stumbled upon someone who seriously believes in geocentricity (no, Mr Gates, that was not a typo). Trinity (a prolific denizen of Craig-Land) believes that the Earth does not orbit the sun, but rather the sun orbits the earth. And his big challenge, the one he throws out regularly, is to show how the speed of our orbit around the sun can be measured.
Now, as far as I can tell, this person is not Robert Sungenis, but rather he is a follower of Sungenis which means that he does not base his geocentrism on the Ptolemaic system with all the complicated epicycles and so on, but rather on a simpler model which approaches the Tychonic system. Sungenis too has put out a "Heliocentric Challenge", which calls for evidence that "the Earth revolves around the Sun" – and offers $100,000 to anyone who successfully meets the challenge.
The first problem to get out of the way is terminology. If we are going to be technical, I feel it is better to say that the Earth orbits the Sun, and more accurately the centre of the combined mass of the Earth and Sun, and even more accurately the centre of the combined mass of the entire solar system. But if we are going to be loose with the terminology, then I guess we can say that the Earth moves in what is very close to a circular orbit around the Sun and we can call that "revolving around the Sun".
Then we need to consider the stars and the CMB. These are important because we need to work out whether, in Sungenis' model, the Earth rotates on its axis. According to this discussion, it would appear that everything moves around the Earth in Sungenis' view, which explains the use of the term "revolves around" rather than "orbits". Under any reasonable and strict definition of the term "orbit", it could not be said that the CMB orbits the Earth, but it does appear to revolve around the Earth. Why it should actually revolve around the Earth is a little unclear, but I guess it has something to do with Sungenis' god.
So, in the model that I am attempting to show to be wrong, the Earth sits fast, and everything else moves around it.
To show this to be wrong, we need only consider the gyroscope that, in a viscous fluid or when appropriately weighted, tends to point north. We can apply other forces to gyroscopes, greater than the centripetal force imbued by the Earth's rotation, to see how the gyroscope reacts to forces in general. Then we can see that, in the absence of any other forces, the combination of gravity and centripetal force has a similar effect on the gyro – from which we can deduce the reality of the centripetal force. Which means that the Earth is actually rotating.
Once we have a rotating Earth, Sungenis' model begins to fall apart. The "rest of the universe" no longer revolves around the Earth. There will be an apparent movement of the Sun relative to the rotating Earth, and once it is all worked through, the Sun will be shown to be almost entirely stationary, with only relative movement that can be (almost entirely) accounted for by the orbit of the Earth around the Sun (there'll be minor wobbles due to the Moon and other planets).
Now that we know that the Earth orbits the Sun, it becomes relatively trivial to work out its speed. Perhaps Sungenis (and Trinity) will quibble about the distance from the Sun to the Earth, but this will only introduce a question regarding the magnitude of the orbital velocity – not about the fact of an orbital velocity. As soon as they accept that the Earth has an orbital velocity, their model is destroyed anyway.
Of course, it is possible that Sungenis has an argument as to why gyrocompasses work, but it would have to be convincing and it cannot be ad hoc. "Aha, but god makes them work by means of directional magic" simply won't do.
The above doesn't explain the newest foray into special relativity. I put that together because Trinity blandly stated that he doesn’t believe in relativity but instead believes in classical physics. As if it were choice!
Perhaps it's entirely wasted effort, since Sungenis' website has the title "Galileo was Wrong", but I am pretty sure this is a reference to Galileo's support of Copernicus, not what later became Newtonian (or classical) mechanics. My point is that relativity is right there, embedded in classical mechanics.
To deny it, one has to deny that light (and thus the transfer of information) has a particular speed. Sungenis doesn't appear to do that, although he (and Trinity after him) does deny that the speed of light is a limit. It is possible to suggest that light travels at all sorts of speeds, depending on who-knows-what, but as I point out in Galilean to Special in One Page, this won't save him.
The only escape appears to be wholesale denial of physics (or wholesale obfuscation combined with copious amounts of hand-waving). Or maybe, just maybe, a commitment to abandon the Book of Genesis as a guide for celestial mechanics.
Perhaps we will see which he will go for.