[timey]

But free fall is indicating that velocity isn't mass dependent, so why would mass be velocity dependent?

[Mike Gale]

You're confusing the classical concept of free fall with the relativistic one. The equation of motion v=at holds in both cases. It is only the momentum (or energy) associated with v that is different.

[timey]

Well since relativistic effects have been experimentally confirmed at speeds under 30 miles an hour, then I think we can ditch the classical approach
And if it is momentum that changes with v = a, then in the case of free fall surely the energy change in momentum is due to that which is the cause of the acceleration, and not that which is being accelerated.

[Mike Gale]

It's a bit of both. Mass increases with velocity and velocity increases with acceleration. That's why GR theorists prefer 4-momentum. It reminds them that relativistic mass is a consequence of spacetime dilation. It's typical insider terminology though. They want to make you feel stupid if you prefer to think in terms of relativistic mass. It's so passe.

[timey]

Space time dilation of space, or space time dilation of time?

[Mike Gale]

Both. That's what SR teaches us.

[timey]

I've taken last few posts to your thread not to clog up Jeff's because we are getting off topic, but there's something I need to ask you.

[timey]

However... which I think that is relevant to this thread, I have said:

And if it is momentum that changes with v = a, then in the case of free fall surely the energy change in momentum is due to that which is the cause of the acceleration, and not that which is being accelerated.

... and you have said:

It's a bit of both. Mass increases with velocity and velocity increases with acceleration.

So the fact that velocity increases with acceleration is due to the energy of the accelerant, surely?
How can it be anything to do with the mass value when any value of mass accelerates at same rate in free fall?

[Mike Gale]

Free fall is really a classical concept. The relativistic equivalent is uniform motion along geodesics. The difference is that Newton "makes no hypothesis" about the cause of the force whereas Einstein attributes it to spacetime dilation.
Geodesics are easy to visualize when the test mass is spiralling around the gravitating mass. Falling straight down is a bit of a mind bender. GR theorists like to think of it as space flowing towards the central mass, dragging the test mass with it. (Or is it away from? I can never remember.) The alternative view is space getting squashed, but it's harder to account for motion in that case because you have to represent the test mass as a wave (or rather two of them, one in each reference frame.) In either case, it's much easier to understand if you can think of it in mathematical terms.

[jeffreyH (OP)]

Neither of you know what I am getting at since I haven't declared intent.

[syhprum]

The statement that a body falls to the Earth with an acceleration of 9.8m/s/s is an approximation that is only correct if it is falling from a short distance away the further away it starts from the weaker the gravitational attraction.

[timey]

Neither of you know what I am getting at since I haven't declared intent.

Jeff this is true - but the post below gives an inkling...

Now if the velocity isn't constant we have a way of linking time dilation to particles with rest mass via the change in the wave characteristics.

Free fall is really a classical concept. The relativistic equivalent is uniform motion along geodesics. The difference is that Newton "makes no hypothesis" about the cause of the force whereas Einstein attributes it to spacetime dilation.
Geodesics are easy to visualize when the test mass is spiralling around the gravitating mass. Falling straight down is a bit of a mind bender. GR theorists like to think of it as space flowing towards the central mass, dragging the test mass with it. (Or is it away from? I can never remember.) The alternative view is space getting squashed, but it's harder to account for motion in that case because you have to represent the test mass as a wave (or rather two of them, one in each reference frame.) In either case, it's much easier to understand if you can think of it in mathematical terms.

Mike - If the accelerative force is temporally derived, then one can explain the acceleration in physical terms as well as being able to calculate.

Edit:  This would mean that the g-field is temporally spatial, instead of spatially spatial, and lights wavelength will get shorter, and it's frequency will escalate in the greater g-field closer to M.
Test particles with mass will be accelerated into the greater g-field by the accelerative phenomenon of seconds becoming shorter in the g-field, but being of rest mass - they will themselves be inherent with longer wavelengths and a decreasing frequency as they are accelerated by the temporally derived g-field into the lower gravity potential.

[Mike Gale]

Neither of you know what I am getting at since I haven't declared intent.

Are you going to? I am intrigued.

[Mike Gale]

The statement that a body falls to the Earth with an acceleration of 9.8m/s/s is an approximation that is only correct if it is falling from a short distance away the further away it starts from the weaker the gravitational attraction.

Of course. It's just lazy language. Acceleration is obviously not constant in free fall.

[Mike Gale]

Mike - If the accelerative force is temporally derived, then one can explain the acceleration in physical terms as well as being able to calculate.

I think you meant to say that acceleration changes over time. That is correct for the free fall case, but it doesn't make the math any easier. Quite the contrary. It's probably easier to think of acceleration as a function of position rather than time because it doesn't change if you hold your position. I think that's the point you were trying to make in your edit.

[timey]

No - I'm suggesting that acceleration is due to time dilation.  That it is changes in the rate of time inherent to the g-field itself that causes the phenomenon.

[jeffreyH (OP)]

Neither of you know what I am getting at since I haven't declared intent.

Are you going to? I am intrigued.

I still need to review a few things first. Then I'll be writing it up.

[jeffreyH (OP)]

Now that I have a little more time here is why this is not valid for photons. If E = wfp then since for the photon p = h/w then the equation becomes E = wfh/w = fh. So that we end up with fh = h/w. This then gives fw = h/h meaning that fw = 1. This cannot be true.
Scrub that it should be fh = hc/w. Which gives fw/c = h/h which is valid. Not the direction I was going in but interesting. I think I need a holiday!

[jeffreyH (OP)]

Ok so here is a conundrum. We can say that w = E/pf. If we want to define dw = ? for a remote frame in a far lower potential then what changes on the right hand side in order for us to calculate the change in wavelength? Is it everything in proportion? Just frequency? Energy or momentum? Will wf still equal c? Is this due to time dilation?

[Mike Gale]

No - I'm suggesting that acceleration is due to time dilation.  That it is changes in the rate of time inherent to the g-field itself that causes the phenomenon.

It amounts to the same thing. If you give me something that depends on time, I can multiply by c and turn it into a spatial dependency. The question is whether the something actually changes over time when it's sitting still. If not then it is a spatial dependency.