[Tron]

well this was an interesting post.  it shed some light on the understanding Einstein and others had as they developed Relativity. 

[jack44556677]

Maybe you can show me where in any of the things he wrote he says anything like what you claim.

Perhaps I can!  However, do you know who coined the phrase - "genius is knowing how to hide your sources"?

How can something that appears to happen in nature conflict with nature?

I agree, this is a somewhat nonsensical question.  There's nothing you can say that can't be said : there's nothing that can happen in nature that conflicts with nature.

Something can appear to happen that is in conflict with nature (the limited slice of it we know) when it only APPEARS to or our understanding of nature is wrong/incomplete.

And it wasn’t  the “action at a distance” that conflicted with relativity.  It was the instantaneous action at a distance of Newton’s gravity.

Both are a major problem for gravitation.  As I said, this is something that most all physicists since newton understood.  By einsteins time it was a famous problem in physics, almost centuries old by that point.

SR showed that nothing can propagate through space faster than the speed of light, including gravity.

This would be ONE major problem for instantaneous action at a distance, yes. The major one we are discussing, however, is the acute lack of mechanism/description/definition of WHAT gravitation is and how it accomplishes its many miracles.

Newton assumed gravity acted instantaneously, so relativity was incompatible with that.  Relativity solved that by showing that gravity doesn't act instantaneously.

 

If by "solved" you mean "ignored" and "showing", you mean "assuming" - then yes, that's correct.

That’s true.  The challenge is coming up with a theory of cause is that it is consistent with the effects we perceive.

Gravitation IS the theory of cause.  It's just piss poor. 

Relativity is an aether theory (though I doubt you were taught this).  It mathematically presumes a physical substrate to "empty" reality which contorts with the presence of mass.  The contorting of this aether is the presumed cause of gravity in relativity.  Empiricism demands that we provide observational and experimental support for the theoretical entity itself (aether/spacetime) as well as the mechanism responsible for matters contortion of it from a distance.  Because we excised aether from the schools, and physics is so poorly taught generally, there was believed to be nothing to go looking for (in part because many that tried found nothing).

the spacetime curvature theory meets all the criteria for explaining how bodies (and light) move.

Not mathematically speaking.  In any case, we are talking about gravitation.  "Spacetime curvature" is just more meaningless gooblety-gook.  Nothing is proposed (or known) to do the warping, nothing is proposed for how it does so at an infinite distance, nothing (mostly) is proposed to be within the two gravitating bodies.  In newtonian theory, something (matter) acts upon nothing (space) to affect the motion of incredibly distant matter (something).  Reduced/generalized this is : Something acts upon nothing which acts upon something. This is fundamentally unacceptable in physics and also what relativity sought to change with its mathematical description of gravitation. 

GR predicts motion of bodies and light perfectly, at least so far.

Also not true, but even if it were - this is a discussion about gravitation NOT relativity.

Again, we have been able to measure those geometric differences and they are consistent with the field equations.

You can't measure something that doesn't exist (or isn't even defined well enough to know how/where to look anyway).

http://www.thephysicsmill.com/2015/12/27/measuring-the-curvature-of-spacetime-with-the-geodetic-effect/

I will check this out.  I don't think I've encountered "the geodetic effect" before.

Spacetime curvature can also be measured by testing how the gravitational field changes as over distance.

So you believe, and you MUST believe - otherwise you can't continue to measure weight and BELIEVE that an invisible undefined "magic" of gravitation is behind the scenes causing it.

The difference in the measurements can tell you how much it curves.

And ASSUME how much it curves, IF it were real, curvable, and being curved by "SOMETHING".  Do you see why this is something very different from empirical science?

[hvanmunster]

Going back to the original post: the cause of gravity may not be entirely understood yet, but that does not mean gravity does not exist.
As an analogy, the cause of universal acceleration is not known either. So why are we discussing whether or not the cause of gravity is known?

Bottom line is that the RE model for gravity better matches with what is observed than the FE model.
The FE model is incompatible with gravitational differences. So they are ignored or dismissed. Board members of this wiki take a very clear position towards gravity: it does not exist in their view and UA is the elementary replacement.
Additional problem for UA: the Sun can consist of a gas or a liquid because UA would flatten it completely - unless the Sun would be surrounded by a transparent solid shell.

[Mark1986]

The major one we are discussing, however, is the acute lack of mechanism/description/definition of WHAT gravitation is and how it accomplishes its many miracles.

Just repeating that there is no mechanism or description of what gravitation s and how it works doesn’t make it true.  GR describes both the mechanism and how it works.

If by "solved" you mean "ignored" and "showing", you mean "assuming" - then yes, that's correct.

I have no idea what you mean by that. Newton assumed that gravity acted instantaneously.  GR shows that gravity doesn’t, nor does it have to. I Nobody is ignoring anything.

Relativity is an aether theory (though I doubt you were taught this).  It mathematically presumes a physical substrate to "empty" reality which contorts with the presence of mass.  The contorting of this aether is the presumed cause of gravity in relativity.  Empiricism demands that we provide observational and experimental support for the theoretical entity itself (aether/spacetime) as well as the mechanism responsible for matters contortion of it from a distance.  Because we excised aether from the schools, and physics is so poorly taught generally, there was believed to be nothing to go looking for (in part because many that tried found nothing)

This is where you ignorance shines the brightest.  There is no shame in ignorance, it can easily be cured by a little education.

Einstein didn’t assume a physical substrate at all.  In fact, he started out trying to prove the exact opposite.  He was an admirer of Mach and like him opposed to the idea of absolute space, to which all motion is relative. If there was any philosophy guiding Einstein’s science it was that space wasn’t a “substrate” or a physical reality.

In 1918, Einstein defined three fundamental principles of GR
"(a) Principle of relativity. The laws of nature are only assertions of timespace coincidences; therefore they find their unique, natural expression in generally covariant equations.
(b) Principle of equivalence. Inertia and weight are identical in essence. From this and from the results of the special theory of relativity, it follows necessarily that the symmetric ‘fundamental tensor’ (gμν) determines the metric properties of space, the inertial relations of bodies in it, as well as gravitational effects. We will call the condition of space, described by the fundamental tensor, the ‘G-field.’
(c) Mach’s principle. The G-field is determined without residue by the masses of bodies. Since mass and energy are equivalent according to the results of the special theory of relativity and since energy is described formally by the symmetric energy tensor (Tμν), this means that the G-field is conditioned and determined by the energy tensor.

That last sentence means that the gravitational field is determined by what is in it.  All motion within the g field is relative to other matter within the field, not the field itself.

Ultimately, he was unable to incorporate Mach’s principle into GR and later disavowed Mach.  The tl:dr is that over the course of 10 years, Albert realized that even if the universe was completely void of any matter, the g field would still exist.

This is a really good account of that process if you are interested.  Like I said there is no shame in ignorance.  But there is shame (or should be) in spouting off things “you know” without any knowledge or education on the matter.

http://philsci-archive.pitt.edu/4377/1/LoveMinusZero.pdf

The first couple of chapters of Brian Greene’s “Fabric of the Cosmos” is also a good account.  I think you can download a pdf of that for free. And it’s easier to read. Anyway, we seemed to have strayed from the OP’s original intent, so if you want to start another thread, I’m happy to discuss further.

[Pete Svarrior]

Bottom line is that the RE model for gravity better matches with what is observed than the FE model.
The FE model is incompatible with gravitational differences. So they are ignored or dismissed.

This is incorrect. It would appear that you have either ignored or dismissed the parts of the model which account for variations in gravity. You'd do well to familiarise yourself with the position you're so proudly disagreeing with.

Board members of this wiki take a very clear position towards gravity

Apparently not clear enough, considering how massively you've cocked up your reading of it.

Additional problem for UA: the Sun can consist of a gas or a liquid because UA would flatten it completely - unless the Sun would be surrounded by a transparent solid shell.

Considering your extremely poor understanding of UA, I'm not expecting much reasoning from you, but you should present whatever you have instead of just stating your conclusion.

[jack44556677]

Going back to the original post: the cause of gravity may not be entirely understood yet, but that does not mean gravity does not exist.

Absolutely! Most everything is not entirely understood, but it exists just the same!

The OP is really about comparing it to magnetism. The cause of magnetism is also not understood - yet demonstrably exists.

As an analogy, the cause of universal acceleration is not known either.

True.  I presume it is the same cause as in the presumptive model.  Whatever powers matter to bend spacetime perpetually is presumably responsible for powering UA.

So why are we discussing whether or not the cause of gravity is known?

Because it has relevance to the OP.  We are comparing gravitation and magnetism.

Bottom line is that the RE model for gravity better matches with what is observed than the FE model.

What FE model?

The FE model is incompatible with gravitational differences

This is a common misconception.  It is frightfully easy to edit a model to match with observation it did not initially predict.

Board members of this wiki take a very clear position towards gravity: it does not exist in their view and UA is the elementary replacement.

I haven't found this to be the case.  Besides, not everyone here has the same views as the wiki.

Additional problem for UA: the Sun can consist of a gas or a liquid because UA would flatten it completely - unless the Sun would be surrounded by a transparent solid shell.

Did you know that every imagined problem has an imaginary solution?  It's trivial to accommodate "paradoxes" like this.

For example, what if you no longer believed the sun were gas or liquid?

[hvanmunster]

1) The FE model is incompatible with gravitational differences. So they are ignored or dismissed.
Your reply:

This is incorrect. It would appear that you have either ignored or dismissed the parts of the model which account for variations in gravity. You'd do well to familiarise yourself with the position you're so proudly disagreeing with.

See the wiki 'Variations in Gravity':
...However, the experiments either do not show variation or the few effects suggesting variations are questionable, contradicted, and may be attributed to other causes...
(this is just one example, taken from that chapter).

UA is incompatible with variations in gravity because, according to UA, the entire world (including Sun, Moon and planets) is accelerating at the same rate in the same directions. This creates a 'virtual' gravitation which is constant in the entire reference frame: same magnitude, same direction, overall

2) Board members of this wiki take a very clear position towards gravity
Your reply:

Apparently not clear enough, considering how massively you've cocked up your reading of it.

No, it's clear enough, see reply n°2 (from AllAroundTeWorld) in this thread and see also your own reply n°2 in the thread "Flat Earth Gravity Explained". You wrote:
It sounds like you have, in many words, re-invented the concept of Universal Acceleration, an inseparable element of elementary FET. Please read the FAQ and skim through the Wiki before posting.

3) Additional problem for UA: the Sun can consist of a gas or a liquid because UA would flatten it completely - unless the Sun would be surrounded by a transparent solid shell.
Your reply:

Considering your extremely poor understanding of UA, I'm not expecting much reasoning from you, but you should present whatever you have instead of just stating your conclusion.

Typo: I meant "the Sun can not consist of a gas...", but I think that was clear enough for anyone reading the post.
When a gas or liquid is subject to a unidirectional force, than this gas or liquid will be levelled out perpendicular to that force. That's what happens with water on the flat earth. So the Sun would be levelled out too, unless it is contained in a rigid shell. Similarly, the Moon and planets must always have been rigid, from the very starting point of their creation. They can never have had a liquid stage throughout their formation.

You are challenging me to reply in the same aggressive way as you are addressing me, but don't hope for that, I will never do that. I prefer to remain polite. Being rude is seen by most readers as a sign of weakness or incompetence. A frustration out of lack of reasonable arguments. I will never lower myself to that level.

[hvanmunster]

So why are we discussing whether or not the cause of gravity is known?

Because it has relevance to the OP.  We are comparing gravitation and magnetism.

I don't think so. We could ask Regicide to confirm, but it seems to me he tried to make this point:
- gravity is rejected by FE because of its 'invisible' force, yet magnetism is not rejected by FE despite that there's an invisible (and partially inexplainable) force for magnetism too.

Bottom line is that the RE model for gravity better matches with what is observed than the FE model.

What FE model?

The FE model as explained on this wiki.

Additional problem for UA: the Sun can not consist of a gas or a liquid because UA would flatten it completely - unless the Sun would be surrounded by a transparent solid shell.
(Quote edited, see word 'not' in bold)

Did you know that every imagined problem has an imaginary solution?  It's trivial to accommodate "paradoxes" like this.
For example, what if you no longer believed the sun were gas or liquid?

Indeed. If there is a UA then the Sun either needs to be a solid or - as I wrote - a gas or liquid which is kept inside a transparent shell, otherwise it would be flattened. You could argue that both are possible, but both are very unlikely.

[Pete Svarrior]

<An absolute mess of misused quote tags and attempts at "no u" responses>

I don't quite think you understand; we might be hitting a language barrier here, so let me try mimicking your blunt tone, which you somehow managed to mistake for politeness. Perhaps you'll find that more accessible.

You will not be able to have this discussion until you've familiarised yourself with the position you'd already decided to dispute. It doesn't matter that you feel very confident and that you can present your uniformed opinions as if they were fact. Until you understand what you're arguing against, your points will land so far from the mark that they won't merit much consideration. For the same reason, they will not be on topic in any thread in the upper.

The moment you revealed yourself to believe that UA would somehow "squash" the Sun was when you revealed yourself to be woefully uninformed. You need to fix this, not protest it.

In your further attempt at argumentation, you decided that UA is a unidirectional force. Considering the fact that this mistake was already corrected in this very thread (and prior to you posting!), I can only assume that you lack argumentation, or that you failed to read and understand the discussion that's being had here. Why else would you say something you already know is completely wrong?

You also argued that this is analogous to water on the Earth's surface. You know, one of those things which aren't directly subjected to UA. This is where your appalling understanding really shines through. "If UA affects the Sun, then it should act like water on the Earth" as an argument boils down to "something affected by UA should be indistinguishable from something expressly unaffected by it". Or, in terms of propositional logic: true is false. Poor effort!

Finally, your core argument is that you found a sentence which reads "However, the experiments either do not show variation or the few effects suggesting variations are questionable, contradicted, and may be attributed to other causes" and that you decided to interpret it as meaning that the effect is not observed at all, or even that it cannot be observed. As I originally suspected, your failure is one of reading comprehension. You're gonna have to fix that, my friend - no one here is going to waste too much time doing your homework for you.

[Kokorikos]

You also argued that this is analogous to water on the Earth's surface. You know, one of those things which aren't directly subjected to UA. This is where your appalling understanding really shines through. "If UA affects the Sun, then it should act like water on the Earth" as an argument boils down to "something affected by UA should be indistinguishable from something expressly unaffected by it". Or, in terms of propositional logic: true is false.

Water is not directly subjected to UA, but it is subjected indirectly by Earth pushing it upwards. This is why it is "flat". If the Earth consisted only of water then the ocean would still be flat because of UA (assuming that UA could affect water in this scenario).
So if UA applies to the Sun then it should also be flat unless it is a solid object or a liquid/gas in a container as hvanmunster suggested.

In any case this is a debate so I do not understand why one needs to be replying in an aggressive manner.

[Pete Svarrior]

Water is not directly subjected to UA, but it is subjected indirectly by Earth pushing it upwards. This is why it is "flat".

This is correct.

If the Earth consisted only of water then the ocean would still be flat because of UA

This, emphatically, is not. Over time, it would form a sphere.

(assuming that UA could affect water in this scenario)

That's not actually what you're assuming, though I can see why you would be confused. Let's try and outline the actual assumption required for your conclusion to hold and see if you can work things out from there.

For UA to "flatten" your hypothetical globe of water, it would have to not apply uniformly to all water particles. In other words, you're imagining a hypothetical force pushing just on the bottom of the sphere, thus causing it to spread out. Or, in other words, it would have to not apply to the vast majority of the water involved.

At its core, your confusion stems from the fact that you're treating UA as if it was a singular unidirectional force - something we corrected everyone on very early on in this thread.

In any case this is a debate so I do not understand why one needs to be replying in an aggressive manner.

It is entirely up to you to decide what you do and don't find aggressive. I cannot force you to interpret my writing in the way it was intended, and it's equally possible that your and hvan's intent is not making its way across. To me, the presumptuous and pompous approach of "Your theory says X! What's that? You're telling me it doesn't? Well, it clearly does, because I said so! You therefore clearly believe X and X is wrong!" is worse than being aggressive - it's intellectually dishonest and lazy. Both you and hvan need to learn what you're arguing against, preferably before you decide that you'll die on the hill of opposing it. I can help you with that, but only once you've stopped strawmanning us and started engaging in meaningful discussion.

This is significantly worsened by hvan's proud announcement of how polite he thinks he is, while simultaneously showing himself to be completely unaware of the cultural norms here. As a guest here, he'll have to adjust one way or another. Until then, he won't find much patience out of those of us who deal with dozens of similar people every day. Again, you may choose to interpret that as rude, but it's just the economy of scale at play. If you don't wanna be treated like yet another generic noob who failed to do his homework, stop being one.

[Kokorikos]

So just to check if I understood what you wrote, if the Earth was originally a globe then under UA it would remain one as all the atoms would be pushed upwards by UA with an equal force. And if it started as a flat plane then it would continue to be one for the same reason. Is this correct?

I cannot answer about havn, but I can assure you that I am simply trying to understand what it proposed by FE.
I am not an expert on it and cannot remember all the details in the wiki and more importantly I do not understand all that is proposed in there. It is very likely that on occasion I will ask something that is already covered in the wiki/forums, but please consider this as an unintentional mistake.

[Pete Svarrior]

So just to check if I understood what you wrote, if the Earth was originally a globe then under UA it would remain one as all the atoms would be pushed upwards by UA with an equal force. And if it started as a flat plane then it would continue to be one for the same reason. Is this correct?

Not necessarily. The current understanding of the UA phenomenon is that it affects all mass, but the Earth (and possibly other bodies) exhibit some sort of shielding effect (which, for example, prevents objects on the Earth's surface from being equally accelerated, thus creating the effect of gravity). This is likely somehow linked to the celestial bodies' mass or density, but we have very few means of exploring that whilst earthbound, so take that last bit as nothing more than wild speculation.

I am not an expert on it and cannot remember all the details in the wiki and more importantly I do not understand all that is proposed in there. It is very likely that on occasion I will ask something that is already covered in the wiki/forums, but please consider this as an unintentional mistake.

Noted and appreciated. I think I can speak for everyone here when I say that it's OK to ask questions, and it's also OK to make mistakes - both of these things are part of the process! It only really grinds my gears when people insist that they understand FE better than the FE'ers themselves.

[jack44556677]

Just repeating that there is no mechanism or description of what gravitation s and how it works doesn’t make it true.

Of course not!  I repeat it only in the hopes that you will understand me.  Perhaps we should try this in reverse - what is the mechanism or description of what gravitation is (not gravity, or "warped spacetime") and how it works (NOT what it is believed to do!)? First outline the theory (which does not rigorously exist to describe) and then outline the empirical/scientific support for the reality of gravitation.

Newton assumed that gravity acted instantaneously.

I would argue he concluded it from observation, but sure.

GR shows that gravity doesn’t, nor does it have to.

GR ASSUMES that gravity doesn't nor does it have to.

This is where you ignorance shines the brightest.

I assure you the feeling is mutual, however people rarely learn anything when being explained that.

There is no shame in ignorance

There doesn't have to be, anyhow.  There often is.

it can easily be cured by a little education.

If only it were so so simple! I've been educating you this whole time while you have tried to do the same...  Ignorance is a pernicious foe, and education takes time and earnest commitment!

Einstein didn’t assume a physical substrate at all. 

Wrong.  I recognize we were taught this, but it is false.  Mathematically, philosophically, and literally - relativity is an aether theory. You can hear it from the horses mouth if you wish.  I think this will take a little more discussion to fully convey - you don't seem to be following.

If there was any philosophy guiding Einstein’s science it was that space wasn’t a “substrate” or a physical reality.

Physics is a branch of philosophy.  There was lots of religious and philosophical ideology influencing einstein.  There is no trouble with a relative aether (one of the ideas/concepts floating around at the time).   A substrate is required if you are going to contort it in order to affect action at a distance by it as an intermediary.  We are discussing philosophy, if you hadn't noticed yet.

That last sentence means that the gravitational field is determined by what is in it.  All motion within the g field is relative to other matter within the field, not the field itself.

There is no gravitational field.  Except in equation/theory.  In physics, it is anathema to have something act upon nothing.  Mass cannot contort spacetime thereby affecting distant matter unless spacetime is real/physical.

Albert realized that even if the universe was completely void of any matter, the g field would still exist.

In imagination, all things are possible!

Like I said there is no shame in ignorance.

We agree there doesn't have to be, but there often is.  I would say there is no shame in being wrong (there is deep shame in refusing to recognize/admit you are)

But there is shame (or should be) in spouting off things “you know” without any knowledge or education on the matter.

Agreed.  Just as there is shame presuming someone is wrong/knowledgeless/educationless merely because their perspective differs from your own.

Anyway, we seemed to have strayed from the OP’s original intent, so if you want to start another thread, I’m happy to discuss further.

I wonder about that.  Only the op can confirm, but I think we are right on topic (more or less).  I'm also most happy to continue to discuss!

[jack44556677]

- gravity is rejected by FE because of its 'invisible' force, yet magnetism is not rejected by FE despite that there's an invisible (and partially inexplainable) force for magnetism too.

Looks like we're all on the same page then.  As I said, the op was about comparing gravity to magnetism/static and exploring why one was frequently denied to exist while the other two are accepted - when they're all "invisible".

The FE model as explained on this wiki.

The wiki is not a bible, nor an encyclopedia.  There is no accepted/agreed upon model, and the wiki outlines multiple models (that are not necessarily compatible).

Indeed. If there is a UA then the Sun either needs to be a solid or - as I wrote - a gas or liquid which is kept inside a transparent shell, otherwise it would be flattened. You could argue that both are possible, but both are very unlikely.

Through imagination, all things are possible.  We can always imagine how it might work - how we could potentially reconcile any paradox.  As you said, we could even argue that "both are possible" without difficulty.  The sense I've gotten is that UA is most often conceptualized to push on either only the world, or the world and the visible heavens at the same time.