Please elaborate on the UA

Oh gosh, I didn't know velocity and acceleration are different things. Thanks for telling me! 

I'll assume you're too high and proud to admit you were wrong.

Puttah, Ski, this is REALLY pointless. One of you be the bigger person and just let it go.

The energy requirement may be finite at any time, but it's potentially infinite, it's unbounded. As you said, it approaches infinity as the velocity approaches c, which we've agreed it's doing. So the energy is constantly increasing. This is not impossible, but we can agree that the UA is pretty weird to do this. It's quite considerate, making sure that we don't get a wobbly impression of gravity by always increasing its energy by the right amount.

Puttah, Ski, this is REALLY pointless. One of you be the bigger person and just let it go.

The energy requirement may be finite at any time, but it's potentially infinite, it's unbounded. As you said, it approaches infinity as the velocity approaches c, which we've agreed it's doing. So the energy is constantly increasing. This is not impossible, but we can agree that the UA is pretty weird to do this. It's quite considerate, making sure that we don't get a wobbly impression of gravity by always increasing its energy by the right amount.

This is a "fine-tuning" arguement which is not very convincing.  There are many aspects of the universe that appear finely-tuned, which you are free to believe as a curiosity, but is utterly unprovable, and therefore has little value.

It's a matter of Occam's razor. We can assume a constant force, observed in the lab (and which explains orbits and non-uniform gravity as well), or we can assume a force of ever increasing magnitude which manifests itself as the appearance of a constant force when it could follow any other curve.

Also, fine tuning arguments are really only used when an aspect of the universe appears fine tuned for our survival, e.g. the values of fundamental constants which prevent the universe from blowing up. They can all be refuted by the anthropic principle. Unless perfectly constant gravity, without any temporary fluctuations at all, is essential for survival, this cannot be refuted as such.

Finally, there's a big difference between fine tuning a number and fine tuning a function.

. As you said, it approaches infinity as the velocity approaches c, which we've agreed it's doing. So the energy is constantly increasing.

It is also possible that the energy is not constantly increasing.

Quote from: alexhall on April 10, 2013, 10:00:42 AM

. As you said, it approaches infinity as the velocity approaches c, which we've agreed it's doing. So the energy is constantly increasing.

It is also possible that the energy is not constantly increasing.

The energy requirements would constantly increase as the relativistic mass of the Earth increased.

Quote from: alexhall on April 10, 2013, 10:00:42 AM

. As you said, it approaches infinity as the velocity approaches c, which we've agreed it's doing. So the energy is constantly increasing.

It is also possible that the energy is not constantly increasing.

Ok you really need to explain this.

Quote from: Ski on April 10, 2013, 05:57:26 PM

Quote from: alexhall on April 10, 2013, 10:00:42 AM

. As you said, it approaches infinity as the velocity approaches c, which we've agreed it's doing. So the energy is constantly increasing.

It is also possible that the energy is not constantly increasing.

Ok you really need to explain this.

Because the velocity is wholly dependent on the frame. Thus too, is the relativistic mass/momentum/energy requirement.

Quote from: jason_85 on April 10, 2013, 10:22:36 PM

Quote from: Ski on April 10, 2013, 05:57:26 PM

Quote from: alexhall on April 10, 2013, 10:00:42 AM

. As you said, it approaches infinity as the velocity approaches c, which we've agreed it's doing. So the energy is constantly increasing.

It is also possible that the energy is not constantly increasing.

Ok you really need to explain this.

Because the velocity is wholly dependent on the frame. Thus too, is the relativistic mass/momentum/energy requirement.

Ah, sorry I misunderstood. I thought you meant that the kinetic energy of the UA (from its own reference point) is not constantly increasing, which wouldn't really make sense.

The kinetic energy of the UA from it's own FoR would be zero 

The kinetic energy of the UA from it's own FoR would be zero 

Hmm, yes and no. Let me rephrase the statement to remove ambiguity;

The rate of change of momentum of the UA from an inertial reference frame traveling with the UA should be constant and positive.

(ie. the UA is accelerating, I only phrased it this way because I had mistakenly thought you were referring to that earlier)

It certainly seems to be...

It certainly seems to be...

Yes, it's a very interesting question (the necessary acceleration of the UA), and that's what I was trying to get some answers to in the other thread..