J.C.MacSwell

Tell him he's crazy...6 THOUSAND years! Tell him the Universe was created 5 minutes ago and unfolded from there. Get him to prove you wrong.

There is an impulse/reaction when the photon is created. So there is, presumably, a force for some duration.

That was my point, though I don't see it as a contradiction. Any nonzero distance (as measured in every current rest frame) between two objects cannot be maintained while they are accelerating (in the direction of the distance between them) while they stay in shared rest frames. A distance (a maximum of which is limited by their separation and rate of acceleration...ie. Frank can't break the laws of physics) can be maintained with respect to the rest frame of one or the other, but not both.

No. Bert would require Frank to finish adjacent to the bow of the Old Model Spaceship, which would have required him to move in the opposite direction at much higher than light speed, yet remain at rest with respect to him at the same time.

I would say it implies that Frank and Bert can not remained synchronized.

Let's say we have a Docking Station 1 light year long, with an additional extention on each end, 2 light seconds long. Brand New Spaceship tied to it, also 1 light year in length. Sister ship to Old Model Spaceship which is identical but has "old technology" propulsion, that limits the acceleration capability. The new rockets on Brand New Spaceship are so powerful that they can accelerate mass to 0.866c in 1 second. To minimize the stresses during acceleration Brand New Spaceship has many of the new rockets spread out along it's length and will be synchronized to work together by a number of well trained Operators. For the maiden voyage they have decided to have an impressive start with a full acceleration take off. Chief Operator Captain "Bert" is at the back of the ship waving to Dockyard Worker "Betty". Some months earlier they had noticed the front of Old Model Spaceship pass by in the direction of the front of their new craft. It was still passing by even though they estimated her speed to be 0.866c. First Mate Operator "Frank" is at the front of the ship waving to Dockyard Worker "Fiona". They had still seen no sign of Old Model Spaceship even though they new she was scheduled to fly by. All the Operators had their watches synchronized and were ready to engage there rockets at the agreed upon time. They understood the importance of the timing to the structure of Brand New Spaceship. As the start time approached, Bert and Betty noticed the stern end of Old Model Spaceship finally approaching. Still no sign of Old Model Spaceship for Frank and Fiona. The start time came, and all operators engaged their rockets for a full and smooth 1 second "burn". Each rocket accelerated perfectly and after 1 second "rocket time" each portion of Brand New Spaceship was at 0.866c, as measured from the Dock. Betty and Fiona, after allowing for the transmission time, considered this to have taken more than 1 second, but still less than 2, so they considered this at least a partial, if not overwhelming, success. Bert was ecstatic. Referencing the Dock, he knew he had reached 0.866c. Not only that, but he glanced over to see a number of cheering passengers on the stern end of Old Model Spaceship. In only 1 second, from a dead start, he had matched their speed. He was now in the same rest frame as Old Model Spaceship. Frank was also ecstatic. He also knew he was at 0.866c relative to the extension at his end of the Dock. But he still saw no sign of Old Model Spaceship. Nor did Fiona. For them it was no where in sight. Not that it surprised them, as Fiona still wasn't expecting to see it for months. What happened? Is Frank in the same rest frame as Old Model Spaceship? Is he in the same rest frame as Bert? Is Brand New Spaceship still intact? Is there an absolute limit on acceleration that depends on length? Can anything accelerate while all it's parts stay in exactly the same shared rest frame at all times?

Isn't that regarding velocity of the receiver? The OP seems to be concerning velocity of the emitter.

It's usually not significant because no rockets are a light year in length, or even anything close to a light second, nor do they accelerate instantaneously to .866c. A relative rocket avoids contracting because the front end and back end accelerate differently, and until they stop accelerating they are actually in slightly different rest frames This effect would be superimposed, or additional to the other physical/structural effects you are suggesting, so setting them aside for now there would still be additional stresses and strains on the rocket. All points along the rocket cannot remain at rest with respect to each other while accelerating. If the front and back synchronized to an agreed on 1 second acceleration to .866c, and started at the agreed on time, would they later, after the acceleration, agree that they had both started at the same time? Finished the acceleration at the same time? If they cannot, then how could they have always shared the same rest frame?

It won't work in the second case when they are a light year apart. At a light second apart it's closer, but I think they are still too far apart for it to work at 0.866c, unless the observers accelerations were more gradual. The "appearance", makes it a little more complicated. It is somewhat tricky just maintaining the displacement wrt the observer alone.

Because of length contraction. Until they are back to the initial rest frame the distance in their frame of rest would have changed. An extra displacement of one is required to maintain the separation distance as measured in their current rest frame. So they cannot be at rest with respect to each other and maintain that same distance at all times. A distance can be maintained, from the viewpoint of the observer or the object, but not both. The farther apart the observer object are, the more gradual the observers acceleration must be to allow enough time for the extra displacement of the object. For a light year distance to change to 1/2 a light year in the changing frame of the observer, the object would have to displace that much distance again, and of course this cannot exceed c in any inertial frame. So even if he left early to allow for the lag, the distance is to great in this set up. It has to be much closer, slower, and at a more gradual acceleration.

If they synchronized clocks and performed the same actions the distance between them would have changed. (unless they are back to the initial rest frame)

That is not what I said. Other than that, only your last sentence, if velocity is taken in the context that I specifically stated, is correct. Everything else is wrong.

I don't think they can, even in the theory, coordinate to maintain the distance and stay at rest wrt each other at all times during accelerations.

You can get a trademark on it, if it is a unique enough design of "isosceles triangle", though if it is actually just a triangle and nothing more, of course it will be rejected for lack of uniqueness.

As long as you recognize what it is that you measuring, average speed in terms of the traveler's moving and accelerating reference frame, while displacing a distance measured in their starting and final inertial frame; then you can make that claim. It is certainly valid for the traveler. There is no limitation of 1.0 c when measured this way. ...and it still is 0.866c measured in the inertial frame where the less than 1.0 c speed limit applies.

Are the wind generators not placed along the route/track? The advantage would be less transmission losses and of course generating electricity from the wind itself, not the apparent wind produced from the train's movement.

No. (obviously, though great question) My take: First of all if n the universe is infinite in size (we don't know) then it would require infinite energy for infinitely long to still not succeed. If the universe is finite then it would require more energy than the universe has to accelerate the spaceship to the "necessary approaching light speed" to accomplish this. In each case, the faster you go...the faster you are displaced toward an area of the universe that has most of it's mass that is at rest in your new inertial frame (due to the expansion)...so the behinder you get. Again great question. Sometimes looking at things from extremes brings up a lot of interesting ideas.

It's an analogy. I think it is an appropriate one. If you are confident in your logic and arrive at an incorrect answer then you should check your assumptions. Your post only makes sense if you assume or believe velocity is something that it is not. Velocity simply does not add the way you would like it to though the difference is not obvious until relativistic speeds become significant.

Lets suppose you are on a circle of 5 mile radius at point A. You walk along the circumference until you are at point B, exactly 1 mile from A. You then walk further on the circle until you are at point C, exactly 1 mile from B. However, you are not 2 miles from point A. Does this prove that not all points on a circle are equivalent? That there are preferred positions? Or does it tell you something about your path?

They are all photons. If you bounce (or absorb) them off something hard enough, you should hear the result.

Interesting idea with the car cooler, though you would have to make absolutely sure it would not let exhaust from a faulty exhaust system into the car when running. That used to kill quite a number of people every year though you hear it less now. It might be better to let the air in from the sides and out the top.

Especially after that Ark fiasco!

The minimum work required is the same, so if you disregard inefficiencies and kinetic energies on arrival (assuming stationary start) you are correct. That is very different from "energy expended" though, which may be your friends point (which he may be holding back?... and if it's not exactly East West he may have a trick!)

Energy expended may not be the same. In each case, I'm sure you would both agree that the potential energy, PE, at the top is the same, and the kinetic energy, KE, as well if you arrive at the same speed still weighing the same (regardless who took how long to get there). But in either case your energy expended will be much greater than your PE and KE at the top. Which took more energy depends on a lot of variables.

I've never done it intentionally, but I'm pretty sure I've done it accidentally, overcooking the core of something I've reheated by leaving it go too long.