[edby]

Objects on the earth's surface have weight because all sufficiently massive celestial bodies are accelerating upward at the rate of 9.8 m/s^2. The mass of the earth is thought to shield the objects atop it from the direct force of UA. Alternatively, it is possible that the force of UA can actually pass through objects, but its effect on smaller bodies is negligible (similar to gravity in RET cosmology, which only has a noticeable affect on very large objects).
https://wiki.tfes.org/Universal_Acceleration

Obviously at some point it occurred that if UA was actually universal, people sitting on top of the surface would be affected by it, so we would all be effectively weightless. Clearly we are propelled downwards when we jump off because while the ground is accelerating upwards, we remain at a constant velocity.

This is quite a conundrum. Some bits of matter are affected by UA, others aren’t. Which? Is it the earth and the rocks in it? Well not the immediate surface. If I pick up a rock and drop it, it falls just the same as me, at the same rate. What about below the surface? What happens in a mine? Do the bits of coal drop off the coal face just as they do on the surface? Apparently they do.

The article suggests that only ‘sufficiently massive’ objects are affected. But no explanation is given of the threshold size, nor of why the size would make a difference. Does the UA act on all parts of the massive object? If so, size would not matter. The force would act on each piece regardless of the larger body it was connected to. Or just one point? But why that point, and why does the earth not bend as a result of the push from that one point.

Separately, where does the energy come from to produce the acceleration? We know the earth is pretty massive, so the force must be massive too. Where does the energy come from? Doesn’t this violate the conservation of energy? If it does, why?

[Rama Set]

Obviously at some point it occurred that if UA was actually universal, people sitting on top of the surface would be affected by it, so we would all be effectively weightless. Clearly we are propelled downwards when we jump off because while the ground is accelerating upwards, we remain at a constant velocity.

This is incorrect. Under UA, the Earth is accelerating upwards, and when we are in contact with it, that force is transferred to us. When we jump, the Earth is no longer accelerating us upwards so we continue upwards at a constant velocity, while the Earth continues to accelerate. From our perspective the Earth rises up to meet our feet, just as it would under gravity.

The only way to distinguish UA from gravity is it’s variability across the Earth as well as tidal forces.

[edby]

Obviously at some point it occurred that if UA was actually universal, people sitting on top of the surface would be affected by it, so we would all be effectively weightless. Clearly we are propelled downwards when we jump off because while the ground is accelerating upwards, we remain at a constant velocity.

This is incorrect.. Under UA, the Earth is accelerating upwards, and when we are in contact with it, that force is transferred to us. When we jump, the Earth is no longer accelerating us upwards so we continue upwards at a constant velocity, while the Earth continues to accelerate.

I don't think I am wrong. Are people affected by UA? Clearly not, because they don't accelerate, as you agree. Is the ground beneath my feet affected by it? No, because if I dig it up, it falls back again. You will say that the ground beneath that bit of ground is the cause. Again no: I can keep in digging the hole (literally) and I will get the same effect. Take any piece of the earth at any depth, and the argument suggests it is unaffected by UA.

Also, read the wiki. "The mass of the earth is thought to shield the objects atop it from the direct force of UA." Why would it say that, if not for the problem I have suggested?

[BillO]

The equivalence principle states that you can't tell the difference between the acceleration due to gravity and an equivalent uniform acceleration.  However there is a caveat.   The observer is not allowed to change their position WRT to the direction of acceleration.  If you change your position like that the difference between uniform acceleration and gravity becomes apparent.  Gravity is a divergent field.  It is inversely dependent on the square of observer's distance from the center of the mass causing the gravity.

If the acceleration we feel on earth was due to uniform acceleration, then we'd feel the same acceleration at the top of a mountain, or even a tall building as we would on the surface.  This is not true of gravity.  Gravity predicts you will fell less acceleration on the top of a mountain or even a tall building.

One of the experiments we had to perform back when I went to university was exactly that.  We were asked to take one of these:  https://en.wikipedia.org/wiki/Gravimeter,  specifically the relative kind, take an calibration reading at the base of First Canadian Place, then take another reading on the top floor (~950') to measure the change.  The experiment was done in relation to our study of the equivalence principle and proved we experience acceleration due to gravity.

I would be very surprised if this simple experiment is not still being done by juniors at universities  all over the world to this day.

[edby]

The equivalence principle states that you can't tell the difference between the acceleration due to gravity and an equivalent uniform acceleration.  However there is a caveat.   The observer is not allowed to change their position WRT to the direction of acceleration.  If you change your position like that the difference between uniform acceleration and gravity becomes apparent.  Gravity is a divergent field.  It is inversely dependent on the square of observer's distance from the center of the mass causing the gravity.

If the acceleration we feel on earth was due to uniform acceleration, then we'd feel the same acceleration at the top of a mountain, or even a tall building as we would on the surface.  This is not true of gravity.  Gravity predicts you will fell less acceleration on the top of a mountain or even a tall building.

One of the experiments we had to perform back when I went to university was exactly that.  We were asked to take one of these:  https://en.wikipedia.org/wiki/Gravimeter,  specifically the relative kind, take an calibration reading at the base of First Canadian Place, then take another reading on the top floor (~950') to measure the change.  The experiment was done in relation to our study of the equivalence principle and proved we experience acceleration due to gravity.

I would be very surprised if this simple experiment is not still being done by juniors at universities  all over the world to this day.

Right, but this was not my point.

My point was, if UA is something like a field which causes everything to accelerate upwards, then the people on top of the earth would be affected by te field and be accelerated upwards by it directly, rather than indirectly via the earth. This clearly does not happen.

[BillO]

My point was, if UA is something like a field which causes everything to accelerate upwards, then the people on top of the earth would be affected by te field and be accelerated upwards by it directly, rather than indirectly via the earth. This clearly does not happen.

I got that and agree with you, but my post was to point out the total folly in their concept of UA.

In that wiki are things like:

Q: Why does gravity vary with altitude?

A: The moon and stars have a slight gravitational pull.

Really?  Where is their model for that.  How does one predict precisely the change in gravity?  If they can't quantify it, it is bunk.  Nothing more.  However, back in the real world all I need is Newton's law of universal gravitation, which predicts it precisely.

They also say things like:

In the FE universe, gravitation (not gravity) exists in other celestial bodies. The gravitational pull of the stars, for example, causes observable tidal effects on Earth.

Gravitation exists, but it's not gravity?  WFT!  Apparently the stars are responsible for tidal effects, even though A) the tidal effects do not follow the apparent motion of the stars but rather the apparent motions of the Sun and Moon B) they can't provide a predictive mathematical model for how this magic 'stuff' happens.  Yet in the real world we can predict tides with ease without having to invoke the stars:
http://oceanmotion.org/html/background/tides-forces.htm

The tide-generating force is produced by the combination of (1) the gravitational attraction between Earth and the moon and sun, and (2) the rotation of the Earth-moon and Earth-sun systems. Forces combine to deform Earth’s ocean surface into a roughly egg-shape with two bulges.

And we have this:

Gravity, or gravitation, is a natural phenomenon by which all things with mass or energy—including planets, stars, galaxies, and even light—are brought toward (or gravitate toward) one another.

So yeah, their UA hypothesis is just bunk and full of holes, inconsistencies and unsupported assertions.

[Pete Svarrior]

If they can't quantify it, it is bunk.

So you're one of those people who think an incomplete model is useless. Noted.

However, back in the real world all I need is Newton's law of universal gravitation, which predicts it precisely.

Ah, but we know that Newton's Law of Universal Gravitation (and, indeed, General Relativity) is incorrect in some cases. It at least indicates that it is incomplete. And we already know what your feelings are about incomplete models. They are bunk.

[edby]

Well there are degrees of incompleteness. Using the gravitational model you don’t have to explain why the earth should be different, why planets travel in epicycles around the earth, why the stars ared fixed etc. You just have a single model that applies to everything, namely matter. The earth follows the same laws as the Sun and Jupiter. You still have to explain why gravitation exists, but that is just one thing to explain, rather than a whole bunch of arbitrary things.

And that’s just Ptolemy vs Newton. With FE there are a whole bunch of extra things to ‘explain’ by ad hoc methods. Prefer the simple and universal model over the complex and specific one.  That’s what science is about, no?

[BillO]

If they can't quantify it, it is bunk.

So you're one of those people who think an incomplete model is useless. Noted.

However, back in the real world all I need is Newton's law of universal gravitation, which predicts it precisely.

Ah, but we know that Newton's Law of Universal Gravitation (and, indeed, General Relativity) is incorrect in some cases. It at least indicates that it is incomplete. And we already know what your feelings are about incomplete models. They are bunk.

Again with the straw men Pete?

More accurately, I think a hypothesis without a model is useless, or as I put it, bunk - meaning nonsense.

Also, if a model provides an erroneous prediction, it is in error, not incomplete.  It's is incomplete when it can't provide any prediction under a demonstrated circumstance within it's stated domain.  Neither Newton or Einstein ever pronounced their models were 100% error free, but they both provide useful predictions and are used all the time to get real usable results.

Your replacement, UA - not so much.  It's model is not incomplete, it is non-existent.

[Pete Svarrior]

Again with the straw men Pete?

Try to address your opponents' points without refraining to kindergarten level of insults.

Also, if a model provides an erroneous prediction, it is in error, not incomplete.  It's is incomplete when it can't provide any prediction under a demonstrated circumstance within it's stated domain.  Neither Newton or Einstein ever pronounced their models were 100% error free, but they both provide useful predictions and are used all the time to get real usable results.

Hold on - if GR is erroneous as you now assert, then how can you be so certain it's useful? The two don't exactly go hand in hand.

[edby]

Hold on - if GR is erroneous as you now assert, then how can you be so certain it's useful? The two don't exactly go hand in hand.

My 12" ruler is pretty inaccurate, measuring lengths to a precision of what - perhaps 2%? Nonetheless it is highly useful for all kinds of things.

[BillO]

In science we test a model through experimental verification.  By applying it to know situations and having it accurately predict them.  See this: https://en.wikipedia.org/wiki/Tests_of_general_relativity for the tests that were conducted on GR.


BTW

Hold on - if GR is erroneous as you now assert, then how can you be so certain it's useful? The two don't exactly go hand in hand.

Is another straw man.  Which is not an insult as I am not calling you a straw man - just your arguments.  So it is an observation of fact.

I did not assert GR was erroneous.  What I actually said was "Neither Newton or Einstein ever pronounced their models were 100% error free...".

straw man
ˌstrô ˈman/
noun
noun: straw man; plural noun: straw men; noun: strawman; plural noun: strawmen

    1.
    an intentionally misrepresented proposition that is set up because it is easier to defeat than an opponent's real argument.
    "her familiar procedure of creating a straw man by exaggerating their approach"

[HorstFue]

Getting get back to somewhat on topic:

The mass of the earth is thought to shield the objects atop it from the direct force of UA.

What's, or better where's the mass of earth? How thick is the 'plate' representing flat earth? 10km, 100km, a few thousands of km? I would more tend to the later.
With this, the much greater part of earth mass is below anything 'we are living in', even the deepest mine.
The other way round anything 'we are living in' is above that mass.... shielded by that mass from the direct force of UA.

[Pete Svarrior]

What I actually said was "Neither Newton or Einstein ever pronounced their models were 100% error free...".

You seem to simultaneously claim that GR is not error-free, and also that it is not erroneous. This appears to be a contradiction. Is it erroneous, or is it not?

[BillO]

What I actually said was "Neither Newton or Einstein ever pronounced their models were 100% error free...".

You seem to simultaneously claim that GR is not error-free, and also that it is not erroneous. This appears to be a contradiction. Is it erroneous, or is it not?

Where did I claim that?  You just printed what I said.  I never claimed GR was error free, I never claimed GR as erroneous.  All I said was that Einstein did not say it was error free. You can tell the difference, right?

Do you want my opinion on GR?  Is that what you are after?  I have yet to read a substantiated claim that it has failed in any way.  I think it remains as useful as it was back in 1915.  It has not demonstrated itself to produce erroneous predictions.

Is this a personal attack Pete?

[Pete Svarrior]

I never claimed GR was error free, I never claimed GR as erroneous.

Since the two are mutually exclusive, this makes your argument the worst kind of position - a self-defeating one.

Is this a personal attack Pete?

No, but asking me is the epitome of uselessness. If you actually think I'm personally attacking you, you should probably raise it with someone else. It would be extremely silly to expect me to self-moderate.

[edby]

On a point of semantics, "not 100% error free" is not at all the same as "erroneous". The latter implies fundamentally or essentially mistaken, the former, that it is not perfect.

[BillO]

I never claimed GR was error free, I never claimed GR as erroneous.

Since the two are mutually exclusive, this makes your argument the worst kind of position - a self-defeating one.

Well, this is just getting silly.  Once more - I never claimed either position.

Is this a personal attack Pete?

No, but asking me is the epitome of uselessness. If you actually think I'm personally attacking you, you should probably raise it with someone else. It would be extremely silly to expect me to self-moderate.

It's not a useless question if you're a person of intellectual honesty.  As a matter of point, I do expect people of good character and intellectual honesty to be self moderating.  If that makes me silly in your eyes, that tells me a lot about you.

Would it be okay if we took this thread back on topic?

[BillO]

On a point of semantics, "not 100% error free" is not at all the same as "erroneous". The latter implies fundamentally or essentially mistaken, the former, that it is not perfect.

Good point, and in discussion semantics are important.

[Pete Svarrior]

Well, this is just getting silly.  Once more - I never claimed either position.

You've explicitly claimed both. It's difficult to proceed until you've made up your mind.

It's not a useless question if you're a person of intellectual honesty.  As a matter of point, I do expect people of good character and intellectual honesty to be self moderating.  If that makes me silly in your eyes, that tells me a lot about you.

Right, and do you want me to be the person to assess my own honesty? What if we disagree in that assessment? What if in my mind you're the one who's engaging in personal attacks and trying to derail this thread with petty (and
erroneous) semantics? It would be rather unfair. This is why we don't self-moderate. Outside of extreme cases, this is done by a third party, one without a vested interest in the conversation.

Would it be okay if we took this thread back on topic?

I'd love to, but it's difficult to discuss models of gravity with someone who simultaneously thinks GR is wrong, not wrong, and neither of the former.

When your assertion is that one model is better than the other, a discussion of either becomes on-topic. You are solely responsible for your dodging of simple questions, and you're the only person who can fix your own position. The sooner, the better.