Genady

To see if you have understood it right, think about the following question. Take a pencil 20 cm long and 0.5 cm thick. Compare the buoyancy in these two cases: 1) you push it under water while holding it vertically, 2) you push it under water while holding it horizontally. In the case 1, the pressure difference between the water underneath and above the pencil is greater than in the case 2. Is the buoyant force different in these two cases?

To be specific, let's say you are in the plane. You clock the time it takes for photon to get from the source to the seat, 0.5 m, and calculate the speed of light, c. I am on the ground. I clock the time it takes for the same photon to get from the same source to the same seat, 200+ miles, and calculate speed of light, c.

Nope. Only one photon left the light source and it did not bounce - there are no mirrors in this experiment. It just left the source and travelled to the seat. Let's to be specific, have a photosensor on the seat that received and registered one photon.

Sometimes exaggeration helps. So, in addition to wonderful explanations and examples above by Eise and others, consider this. Instead of a train, let's do it in a plane, a very fast one. The light source is installed in the plane directly above seat 17A facing straight down to the seat. The plane is flying. When it is above NYC, the flash of light goes out. After very short time it hits the seat 17A. But the plane is really fast. By the time the light hits the seat, the plane is above Boston. The seat 17A moved 200 miles, from NYC to Boston. However, the light hits it anyway. Thus, the light went 0.5 m down and 200 miles NE.

My first language was Russian, too. I don't practice it many years now, but perhaps could help you if you have problems expressing your thoughts or interpreting some responses.

I'd recommend, reading. A lot of reading.

I've interpreted this dance as a "war dance" rather than a mating dance:

I am sorry, but I don't understand the above description. It still looks to me that you are mixing different reference frames. Could you explain it referring to one frame at a time? There are two frames of interest in this situation that I see: Frame A is the one where the clock/mirror is not moving, and the light goes vertically. This is what an observer which is attached to the mirror observes. Frame B is the one where the clock/mirror is moving to the right, and the light goes diagonally. This is what an observer moving to the left relative to the mirror observes. What is your objection?

I am not sure about this. Let's see if they ask a clarifying question.

I disagree. A free falling body is at rest = not moving in its own reference frame.

Yes, it says, unavailable. But I can see other PBS videos. Also, sometimes I get a message saying something like, unavailable in your area, but this just says, "This video is not available." Well, I don't think you can do anything about it

Oops?

On the reefs of Bonaire.

Here they do:

What about unknown knowns? Why are they not on that list?

This was a mistaken conclusion in the OP. Per the data given, v=0.655c.

The clock moves .866 m in the time the light moves 1.323 m. Thus the clock speed is v=.866/1.323=.655c. The time dilation for this speed, gamma=1.323. The time of the full trip of light is (1 m)/c in the clock's reference frame, and (1.323 m)/c in the external observer reference frame. I don't see any conundrum. This is what time dilation is.

This is incorrect. In the time the clock moved .866 m the light covered not 1 m but sqrt(1+.8662)=1.323 m, i.e., 1 m vertically and .866 m horizontally.

How do you get v=.866c? Is it a given?

For me, it would be very sad. Plus, some of the goals are such that failure to achieve them might be quite painful. E.g., one of my early goals was escape from the USSR. A failure in this one meant more than just not escaping. It meant trading my warm city of Baku for much colder places.

I believe they are, although I failed to achieve some of them. E.g., my first marriage.

I measure my success against my goals.

It is so, indeed. I've watched this from within, as lived in the USSR then. The propaganda there magnified all and every failure they could find about USA, big or small. They had nothing bad to say about the Moon landing.

It does not. There is time dilation at work in this experiment, not a length contraction. PS. If there is something confusing in the equations, ask for a clarification.

No, of course not. I suggest that people came to Australia in an earlier migration event. I don't know any more details about that map. I used it to demonstrate to the OPer that the spread was long and not continuous.