Yeah, it’s a pretty disturbing video.
Thought experiments allow you to address fundamental questions about the universe - in this case, the nature of the speed of light limit and its consequences - without having to worry about mundane practical obstacles that prevent the experiment from being done in reality. In this case, we have managed to figure out why you can’t send information faster than the speed of light without having to build a 200,000 mile rod in deep space. That’s a significant savings of tax money, which savings is passed on to you and allows you to buy new televisions.
I’m going to stick my nose in here just to say something that’s been on my mind for some time now. While I’m familiar with the concept of the “thought experiment,” I have always hated the term. It’s an oxymoron.
In my understanding of the scientific method, before one conducts an experiment (an actual one), one must form a hypothesis, which is essentially a prediction of what will happen during the experiment.
If we’re physically unable to perform an experiment, it certainly can be interesting and enlightening to discuss and debate our hypotheses, which is what is going on in this (quite engaging) thread. However, IMO that doesn’t constitute an experiment at all, “thought” or otherwise.
Sorry to interrupt. Carry on.
Thought experiments are useful when they are set up to examine the interaction of various configurations of already-known/understood phenomena and laws - many of the exercises set by school geometry textbooks are thought experiments, for example - you can work out the angle subtended at the observer’s eye when viewing a 20 metre tall tree at a distance of 50 metres, without actually needing to leave the room and find a suitable tree.
The value of a thought experiment is that it helps us to determine reality. Knowing what is possible is essential if we’re ever going to get there.
Your “who cares?” attitude is a little like someone in 1940 saying “Who cares about nuclear fission? It’s not like we know how to build a bomb out of it.”
A rod made of Unobtanium, with a single line of atoms in a perfectly straight rigid line. Would still not oscillate faster than an unimpeded photon in a vacuum by virtue of the distance between the atoms.
How many atoms in 200,000 m + the spaces x time per each oscillation = slower than light speed over that distance in my thought experiment.
:dubious:
(oscillation means whack it with a neutronium phase hammer)
I care about research, I care about inovations.
What I do NOT care for is knowing if someone can move a 200,000 miles long rod faster than the speed of light.
If a thought experiment can help us determine reality, that’s fine, but again, a 200,000 miles long rod is not reality and that’s what I was trying to say.
The trouble is, you don’t know what you don’t know - it is not possible at the outset, to (completely) reliably predict which lines of inquiry are productive and which are frivolous. The ponderings about 200,000 mile long rods are an entirely necessary facet of the same human curiosity that brought about the transistors in the computer on which you are reading this.
Or more to the point, general relativity was discovered at least in part because Einstein wondered if gravity jerked everything instantly at a distance, or if there’s some lag. It’s the same question.
the length of 200,000 miles is technically irrelevant. it may serve a purpose in helping someone visualize the scenario but the point of the experiment is: does the movement of a pole act instantaneously? if so, doesn’t that violate the speed of causation - the speed of light?
all in all, relativity may not have much of a practical consequence… not as much as other scientific theories anyway. otoh, didn’t your mother teach you that if you didn’t have anything nice to say, don’t say anything nice at all? leave these ponderers be.
I’ll take a stab at this and guess that he’s referring to a rod string in wells that are rod pumped. Typically due to weight considerations these rod strings are tapered and so slightly different then what is proposed in the thought experiment. I can go further into detail if you want but I don’t want to hijack the thread for no reason.
Actually, relativity has considerable practical consequence. GPS satellites, for example, have to account for relativistic effects to achieve level of accuracy we’ve been able to obtain from them. If you have one of those handy GPS devices in your car, you are navigating courtesy of Albert Einstein. 
Infinitely? If your rod remains rigid for even four hours, please seek medical attention.
J-P L, is it possible you have wandered into the wrong thread? It’s not very likely you’re going to be part of an important innovation by joining an internet conversation about a thought experiment. As far as research, how does anybody know where it will eventually lead? We don’t need to tell the Moon where to go, for example, but find all sorts of uses now for the calculus.