J.C.MacSwell

The terminal velocity caps the velocity due to aerodynamic drag, therefore capping the kinetic energy of the falling mass not the potential energy, as the drag reduces the rest of the potential energy to other forms, ultimately to heat.

This is basically about math. Regardless of how you view, or believe in, the physics, SR is consistent mathematically. So if you use SR, as an underlying assumption, in a thought experiment and come up with a conflict in the results, you have either made a mistake as to how to use the theory, or made a mathematical error, or have proven the math of SR itself incorrect. So if you are convinced you have not made an error...where exactly is the math of SR inconsistent or wrong? If you do not believe SR is mathematically consistent, point out the inconsistency.

Hmm...how much would it cost to get the weight of the components to flying altitude, plus lift related drag, 1000 times?

From Wikipedia: (last line bolded mine) Roger Penrose[4] advanced a form of this argument that has been called the Andromeda paradox in which he points out that two people walking past each other in the street could have very different present moments. If one of the people were walking towards the Andromeda Galaxy, then events in this galaxy might be hours or even days advanced of the events on Andromeda for the person walking in the other direction. If this occurs, it would have dramatic effects on our understanding of time. Penrose highlighted the consequences by discussing a potential invasion of Earth by aliens living in the Andromeda Galaxy. As Penrose put it: "people pass each other on the street; and according to one of the two people, an Andromedean space fleet has already set off on its journey, while to the other, the decision as to whether or not the journey will actually take place has not yet been made. How can there still be some uncertainty as to the outcome of that decision? If to either person the decision has already been made, then surely there cannot be any uncertainty. The launching of the space fleet is an inevitability. In fact neither of the people can yet know of the launching of the space fleet. They can know only later, when telescopic observations from earth reveal that the fleet is indeed on its way. Then they can hark back to that chance encounter, and come to the conclusion that at that time, according to one of them, the decision lay in the uncertain future, while to the other, it lay in the certain past. Was there then any uncertainty about that future? Or was the future of both people already 'fixed'?"[5] Literally...that, and the Invasion story, was part and parcel to the Andromeda Paradox, regardless of whether the questions are scientific or not, or what you, I, or anyone else thinks about it ...it's simply a historical fact, not my opinion, and not something I made up

...and to add to that, the paradox is that if one assumes a "now" with certain but as yet unknown events taking place on Andromeda, where the other, at the same time and location on Earth but their "now" being days earlier on Andromeda...then what does that say about uncertainty, or inevitability, wrt the future in general?

Sorry, but you are not getting it. We all realize that motion is relative. Forget that I (where did you get that?), or anyone else, insist (again, we don't... it doesn't matter) that Earth is fixed wrt Andromeda. The paradox (and, unlike the twin pseudo paradox, it is a paradox, notwithstanding it is outside and beyond causal/temporal distance) holds for the true/apparent relative velocities of Andromeda and Earth. It is about subtle, seemingly insignificant, changes in velocity of an extremely remote observer/calculator, and how it effects his sense/calculation of what is a simultaneous event at that considerable distance....and it has nothing to do with the relative velocities of Earth and Andromeda.

Sorry, xyzt. You may be very clear on your understanding, and in that you may be correct, but the paradox is not about the relative speeds of Earth and Andromeda. It is about the distance between them, and how the subtle difference in walking speed of the Earthly observer, in the direction of Andromeda, having a very significant effect on what day it is on Andromeda when he/she considers his/her now. Try not to focus on the simplification "assume Earth and Andromeda are at rest/in the same frame". It is unfortunate that it was used in one example, as it is irrelevant and unnecessary to explain the paradox.

If that is the case, then I'm wrong calling a standard hovercraft a ground effect vehicle. It is supported by the ground due to an increased pressure, rather than thrust or deflection, but not due to an aerodynamic interaction.

There are ground effects on cars, planes, helicopters near the surface...I think the term comes into play when that becomes a significant effect in the design

It is supported by the ground underneath the vehicle, not the thrust from the accelerated air. Compare to a helicopter or plane which power or deflect air downward.

These are primarily ground effect vehicles so the thrust formulas don't really apply. It comes down to area and how much pressure can be maintained underneath the craft against the considerable leakage taking place.

That's not correct. For, say, the moon orbiting the Earth, the Earth is greater than the sum of it's parts...all the kinetic energy bound in the system (just like the runner on the oval track) adds to both the gravitational, and equally the inertial, mass of the Earth. Note how this is effectively different from a straight line kinetic energy. edit: essentially changed to effectively

If he could, somehow, go fast enough around the oval track of an Olympic Stadium, he would indeed create a blackhole. His own mass would not increase, but the mass of the system he is part of would.

In SR: As the clock reaches motionlessness in our frame, it measures the rate of time passage of our frame...we would observe/calculate it as having sped up to match our rate from a previously slower pace. Since it was previously slower, less time would have passed for it. The reading on it would show less time lapsed, since the time it had escaped from us, than any clock of our own that had remained stationary in our frame.

Each World would be a total re-creation/addition of every possible affected frame including all mass and energy in a consistent manner. What would be considered remote or very far away in a process such as this? Occam would very quickly need a chainsaw to shave with... Essentially, same way it "knows" locally, since it equates to the same thing

I think the same way it gets there in a one World interpretation. Both the new paths have common "ancestors" with exponential creation of Worlds. It is a very "busy" theory.

As per 7 years ago, my point is that there is nothing in principle that prevents it being done...

A fan on a boat can generate thrust. A sail or sails can be used to redirect the thrust, including reversing it 180 degrees. The fan without the sail has net thrust, and the fan/sail system can have net thrust. Momentum and energy are of course conserved. Think of a pump (fan) and a hose (arguably a "sail") you can get net thrust in any direction you wish...it is just a little trickier setting up actual sails in the right way but it can be done.

Hi Avner...this is an old thread! Particles carry momentum not force. For a boat and air particle initially at rest: If the force accelerating the particle is the same but opposite in each case, and for the same duration, the particle (and boat) will again be stationary...but the boat will be displaced to the left (not as much as the presumably lighter particle is displaced to the right) You may of course consider this displacement insignificant and ignore it If the force accelerating the particle is the same but opposite, but for more or less duration in each case, the boat will be in motion at some velocity, with momentum equal to but opposite that of the particle.

If it arrived at 1 foot up at 2s; from which direction would it arrive? If it arrived at the top at 60s; from which direction would it arrive?

A spring...to the degree that it is also a damper (almost insignificant for a good spring) . Only an ideal spring does not have any hysteresis. But I think you are after something else...

How do we know it's not reversing right now?

Espergalacanto

In a "perfect world" the perfect cosmological principal would hold: http://en.wikipedia.org/wiki/Perfect_cosmological_principle The Perfect Cosmological Principle states that the Universe is homogeneous and isotropic in space and time. In this view the universe looks the same everywhere (on the large scale), the same as it always has and always will. It is the principle underpinning steady-state theory and emerging from Chaotic inflation theory.[1][2][3] The Perfect Cosmological Principle is an extension of the Cosmological Principle, which accepts that the universe changes its gross feature with time, but not across space.

The unbolded is what Jacques is getting at. The bolded contradicts what was just stated. If the natural rate of expansion (assuming there is one) is being retarded by gravity, but that effect is reduced over time from the expansion, then the expansion will increase over time (accelerate) as it approaches that natural rate. The rate of acceleration will diminish but always be positive. Edit: not sure if that actually fits the data just that it is based on Jacque's assumptions