My Problem with UA 2

Sorry about starting a second thread but the first one has gone from an intelligent discussion to meaningless scrutiny.

Quote from: socrates on August 13, 2007, 03:15:52 PM

But is all the stuff accelerating? Is the sun accelerating? The Moon? The stars?  Or just the earth? Also acceleration is known as a vector quantity, so it has a magnitude (9.81m/s²) and a direction. Where is it acclerating? Please be specific.

Yes, all the stuff we can see, is accelerating.  And it's all accelerating in a direction normal to the planar surface of the Earth. 

But if everything in the universe is accelerating, then there is no force pulling you back, you are moving with the universe at 9.81m/s², and when you jump you will be moving at 9.81m/s²+the force of your jump, I don't see how you somehow forfeit the force of the universal accelerator when you jump, and your jump becomes just the force of your jump.
For example if I were floating in a river next to a boat, with the river moving at a constant acceleration of 9.81m/s², and i began swimming until i was 3m ahead of the boat, then I would remain 3m ahead of the boat unless something were to pull me back to it. Because me and the boat are moving in the same medium. Just substitute river with UA, the boat with the Earth, and swimming with jumping. Unless somehow humans are independant of the UA your argument fails.

Edit: Please leave the question of gravity out of this thread, make your own "My problem with Gravity" Thread, don't put it in mine!

But if everything in the universe is accelerating, then there is no force pulling you back, you are moving with the universe at 9.81m/s², and when you jump you will be moving at 9.81m/s²+the force of your jump, I don't see how you somehow forfeit the force of the universal accelerator when you jump, and your jump becomes just the force of your jump.

Run-on sentence.

Quote from: socrates on August 13, 2007, 03:58:15 PM

But if everything in the universe is accelerating, then there is no force pulling you back, you are moving with the universe at 9.81m/s², and when you jump you will be moving at 9.81m/s²+the force of your jump, I don't see how you somehow forfeit the force of the universal accelerator when you jump, and your jump becomes just the force of your jump.

Run-on sentence.

Lol, sorry, grammar isn't my strong point especially when i get all riled up.

Sorry about starting a second thread but the first one has gone from an intelligent discussion to meaningless scrutiny.

Quote from: TheEngineer on August 13, 2007, 03:30:23 PM

Quote from: socrates on August 13, 2007, 03:15:52 PM

But is all the stuff accelerating? Is the sun accelerating? The Moon? The stars?  Or just the earth? Also acceleration is known as a vector quantity, so it has a magnitude (9.81m/s²) and a direction. Where is it acclerating? Please be specific.

Yes, all the stuff we can see, is accelerating.  And it's all accelerating in a direction normal to the planar surface of the Earth. 

But if everything in the universe is accelerating, then there is no force pulling you back, you are moving with the universe at 9.81m/s², and when you jump you will be moving at 9.81m/s²+the force of your jump, I don't see how you somehow forfeit the force of the universal accelerator when you jump, and your jump becomes just the force of your jump.
For example if I were floating in a river next to a boat, with the river moving at a constant acceleration of 9.81m/s², and i began swimming until i was 3m ahead of the boat, then I would remain 3m ahead of the boat unless something were to pull me back to it. Because me and the boat are moving in the same medium. Just substitute river with UA, the boat with the Earth, and swimming with jumping. Unless somehow humans are independant of the UA your argument fails.

Edit: Please leave the question of gravity out of this thread, make your own "My problem with Gravity" Thread, don't put it in mine!

You're confusing velocity with acceleration. The river is also a bad analogy as a river carries along most all of its contents while an accelerating upwards FE would not.

You do forfeit the effect of the UA when you're not in contact with it. That contact may be lift from an airfoil, a post for a mailbox, or buoyancy for a lighter-than-air balloon. If you jump off of the accelerating FE and you're heavier than air, then you "fall" back to FE.

The RE Primer does have a section on this issue.

When you're traveling in a car, throw a ball in the air. Observe.

When you're traveling in a car, throw a ball in the air. Observe.

You're confusing velocity with acceleration too. What's going on there is wind resistance outside the car, not acceleration. The causes are completely different.

True. I misread what he originally wrote. Sadface 

Actually acceleration would approximate the effects of gravity, except for the fact that it would need to be maintained infinitely which can not happen.  As you approach light speed, acceleration becomes nearly impossible by any force.  Also, visual distortion would become apparent as the speed of light is approached; looking "down" (the direction from which one is accelerating) objects would appear red, looking "up" (the direction to which one is accelerating) objects would appear blue.  This is the Doppler shift; as light always travels at a constant speed, relative to the near-light-speed object (us) the frequency of light would change based on the direction of movement.

Unless Einstein was an exceptionally gifted liar.  Then all bets are off.  But this also causes some embarrassing problems with the fact that the sun's gravity actually bends light emitted from the stars, allowing us to calculate its mass.  There must be some other convenient excuse for this, or else someone had better start working on one.

Actually acceleration would approximate the effects of gravity, except for the fact that it would need to be maintained infinitely which can not happen.  As you approach light speed, acceleration becomes nearly impossible by any force.  Also, visual distortion would become apparent as the speed of light is approached; looking "down" (the direction from which one is accelerating) objects would appear red, looking "up" (the direction to which one is accelerating) objects would appear blue.  This is the Doppler shift; as light always travels at a constant speed, relative to the near-light-speed object (us) the frequency of light would change based on the direction of movement.

Unless Einstein was an exceptionally gifted liar.  Then all bets are off.  But this also causes some embarrassing problems with the fact that the sun's gravity actually bends light emitted from the stars, allowing us to calculate its mass.  There must be some other convenient excuse for this, or else someone had better start working on one.

Sorry. No.

You see FE says that the "felt" acceleration is constantly 1g, not that the FE is accelerating at constant 1g. The effects about which you're concerned here are based on an independent observer, not on the FE. Since we don't have a report from that observer, we can't confirm or deny FE's claim this way.

FE does fail to explain variances in gravity by altitude and latitude and tidal forces.

We've written up the RE Team's consensus on these items in the RE Primer.

Red-shift and blue-shift are also nonexistent, because the observer is travelling at the same rate as the objects he is observing. There would be a very slight red or blue shift because of the difference in speed between the time the light is reflected and the time the observer sees it, but it is exceedingly minute, and GR predicts the exact same thing in a gravitational field, so it doesn't distinguish the two situations. Indeed, it is impossible to distinguish an accelerating reference frame from a reference frame in a constant gravitational field according to modern physics, so the only experiments that have a chance of working are those which detect the nonuniformity of the gravitational field because it is generated by a planet and not because of an accelerating reference frame.

As for the speed of light issue - as gulliver said, it's nonsense. The acceleration is only constant from the point of view of people living on the FE, in the FE model, but actually decreases in any inertial reference frame as the speed of the FE in that frame approaches c. This should be well covered in the FAQ, I imagine, although I haven't bothered to read the updated version.

Red-shift and blue-shift are also nonexistent, because the observer is travelling at the same rate as the objects he is observing

This is irrelevant.  The speed of light is a constant, there is no such thing as the speed of light plus the speed of an object.  The speed of light is the same regardless of reflected object speed, acceleration, wavelength, or any other known factor.

You must have a change in position relative to another object to observe shifting.  If they are both traveling at the same speed, there will be no shift.

Quote from: socrates on August 13, 2007, 03:58:15 PM

But if everything in the universe is accelerating, then there is no force pulling you back, you are moving with the universe at 9.81m/s², and when you jump you will be moving at 9.81m/s²+the force of your jump, I don't see how you somehow forfeit the force of the universal accelerator when you jump, and your jump becomes just the force of your jump.

Run-on sentence.

Another victory for FE!

Now you're getting into the spirit! 

True. I misread what he originally wrote. Sadface 

*fail-o-meter twitch*

Quote

Red-shift and blue-shift are also nonexistent, because the observer is travelling at the same rate as the objects he is observing

This is irrelevant.  The speed of light is a constant, there is no such thing as the speed of light plus the speed of an object.  The speed of light is the same regardless of reflected object speed, acceleration, wavelength, or any other known factor.

TheEngineer is correct. We can do this in either of two reference frames. In one reference frame the ground and the viewer are both stationary. In this reference frame, light moves at the speed of light. Therefore nothing gets shifted, because everyone is stationary.
Now let's do it in a reference frame in which the ground and the viewer are both moving upwards at a great speed. In this reference frame, light moves at the speed of light, of course, because the speed of light is the same in all inertial reference frames. Now the light emitted upwards from the upward travelling ground will be extremely blue shifted due to it's velocity. Now the viewer sees blue-shifted light emitted from the ground. But since he is moving upwards as he sees the upwards travelling light, it is red-shifted by his motion. Since he is moving at the same speed as the ground, the red-shift exactly cancels the blue-shift, and the light appears completely unaffected to him.
Of course, I have only discussed the velocity of the flat earth here, and not the acceleration; in point of fact the light bouncing off the ground will be very slightly red-shifted because the viewer will be going slightly faster when he sees the light than the ground was moving when it reflected the light. But as I said before, this effect is extremely minute due to the short times involved, and is exactly the same as the red-shift due to gravity predicted by general relativity anyways.

Now the viewer sees blue-shifted light emitted from the ground. But since he is moving upwards as he sees the upwards travelling light, it is red-shifted by his motion. Since he is moving at the same speed as the ground, the red-shift exactly cancels the blue-shift, and the light appears completely unaffected to him.

I can't believe I never saw it like that before.  I concede this point, well explained and thank you. 

But the objects would become infinite in mass as they approach light speed unless they actually have no mass in the first place, in which case there is no explanation for the way light from the stars bends as it passes close to the sun's gravitational field.  This also raises questions about how we can measure distant stars' movements by the red/blue shift when they are, according to FE, not far enough away to move that much in the first place.

But the objects would become infinite in mass as they approach light speed

Again, not in our frame of reference.