The Flat Earth Society

Flat Earth Discussion Boards => Flat Earth Theory => Topic started by: fozington on May 16, 2017, 12:57:56 PM

Title: Question from a physicist
Post by: fozington on May 16, 2017, 12:57:56 PM
Hello everyone. 

I have a question for you all.  I've been through the FAQ and, although the concept of gravity is discussed, I couldn't see any reference to this particular point.

Imagine that you're travelling around with an accurate accelerometer (a device which measures acceleration).  At various places you stop and take a measurement, and after a while start to notice that these measurements differ from each other by a small amount.  This shows that the strength of gravity is different at different places on the planet. 

In classical physics this is well documented and can be explained by a number of different phenomena.  For example, according to Newton's law of gravitation [F=G(Mm)/r^2] if you are at the top of a mountain, gravity should be slightly weaker than if you were at sea level.  Also, the non-uniform mass density of the planet can account for some considerable variation, even if measurements are taken at the same altitude.  In fact, the measurement you take can vary by as much as 0.7% from place to place.

Now, as I understand it (and do please correct me if I've got the wrong idea) you suggest that the flat Earth is being accelerated upwards at a constant 9.8m/s^2.  Surely, if that were the case, the acceleration measured at any point on the planet would be exactly the same.

Thanks for taking the time to read this, and I look forward to hearing what you have to say.  Please note, I'm not here as a troll, I just find the whole topic fascinating.

Thanks!

F
Title: Re: Question from a physicist
Post by: Dither on May 17, 2017, 04:54:01 AM
you suggest that the flat Earth is being accelerated upwards at a constant 9.8m/s^2.  Surely, if that were the case, the acceleration measured at any point on the planet would be exactly the same.

Not every FE believes this, some work by density alone.

I'm a bit out of my league now so I'll await someone else's response.
Title: Re: Question from a physicist
Post by: rabinoz on May 17, 2017, 06:23:55 AM
Hello everyone. 

I have a question for you all.  I've been through the FAQ and, although the concept of gravity is discussed, I couldn't see any reference to this particular point.

Imagine that you're travelling around with an accurate accelerometer (a device which measures acceleration).  At various places you stop and take a measurement, and after a while start to notice that these measurements differ from each other by a small amount.  This shows that the strength of gravity is different at different places on the planet. 

In classical physics this is well documented and can be explained by a number of different phenomena.  For example, according to Newton's law of gravitation [F=G(Mm)/r^2] if you are at the top of a mountain, gravity should be slightly weaker than if you were at sea level.  Also, the non-uniform mass density of the planet can account for some considerable variation, even if measurements are taken at the same altitude.  In fact, the measurement you take can vary by as much as 0.7% from place to place.

Now, as I understand it (and do please correct me if I've got the wrong idea) you suggest that the flat Earth is being accelerated upwards at a constant 9.8m/s^2.  Surely, if that were the case, the acceleration measured at any point on the planet would be exactly the same.

Thanks for taking the time to read this, and I look forward to hearing what you have to say.  Please note, I'm not here as a troll, I just find the whole topic fascinating.

Thanks!

F
Junker advises us
"Please make sure to check out these resources to ensure that your time at tfes.org is enjoyable and productive."
so we do that and find: I still query:
I'd like to hear your ideas.
Title: Re: Question from a physicist
Post by: İntikam on May 17, 2017, 08:14:47 AM
Hello everyone. 

I have a question for you all.  I've been through the FAQ and, although the concept of gravity is discussed, I couldn't see any reference to this particular point.

Imagine that you're travelling around with an accurate accelerometer (a device which measures acceleration).  At various places you stop and take a measurement, and after a while start to notice that these measurements differ from each other by a small amount.  This shows that the strength of gravity is different at different places on the planet. 

In classical physics this is well documented and can be explained by a number of different phenomena.  For example, according to Newton's law of gravitation [F=G(Mm)/r^2] if you are at the top of a mountain, gravity should be slightly weaker than if you were at sea level.  Also, the non-uniform mass density of the planet can account for some considerable variation, even if measurements are taken at the same altitude.  In fact, the measurement you take can vary by as much as 0.7% from place to place.

Now, as I understand it (and do please correct me if I've got the wrong idea) you suggest that the flat Earth is being accelerated upwards at a constant 9.8m/s^2.  Surely, if that were the case, the acceleration measured at any point on the planet would be exactly the same.

Thanks for taking the time to read this, and I look forward to hearing what you have to say.  Please note, I'm not here as a troll, I just find the whole topic fascinating.

Thanks!

F

Hello.

Firstly, the earth is stationary and doesn't move to anywhere. That knowledge is "old theory" and debunked several times, also by ourselves.

Most part believers accept the "gravity effect" as caused by atmospheric stringency. You may think it as atmospheric pressure. They are not same by phsically but are about same as effective.

In nature, everything pushes others, including atmospher. So when you are on a mountain, there is less atmospher upper side of you and so, it causes less force to down you. So the gravity is less.

In ground level, the atmospher on your upper side is more than the mountain level, so the gravity effect increases. Thats all.

You can explain every type of gravity effects by changing the atmospheric weight/or hight which effect to the object.

PS: I'm an engineer from 20 years.
Title: Re: Question from a physicist
Post by: Flatout on May 17, 2017, 09:28:32 AM
Hello everyone. 

I have a question for you all.  I've been through the FAQ and, although the concept of gravity is discussed, I couldn't see any reference to this particular point.

Imagine that you're travelling around with an accurate accelerometer (a device which measures acceleration).  At various places you stop and take a measurement, and after a while start to notice that these measurements differ from each other by a small amount.  This shows that the strength of gravity is different at different places on the planet. 

In classical physics this is well documented and can be explained by a number of different phenomena.  For example, according to Newton's law of gravitation [F=G(Mm)/r^2] if you are at the top of a mountain, gravity should be slightly weaker than if you were at sea level.  Also, the non-uniform mass density of the planet can account for some considerable variation, even if measurements are taken at the same altitude.  In fact, the measurement you take can vary by as much as 0.7% from place to place.

Now, as I understand it (and do please correct me if I've got the wrong idea) you suggest that the flat Earth is being accelerated upwards at a constant 9.8m/s^2.  Surely, if that were the case, the acceleration measured at any point on the planet would be exactly the same.

Thanks for taking the time to read this, and I look forward to hearing what you have to say.  Please note, I'm not here as a troll, I just find the whole topic fascinating.

Thanks!

F

Hello.

Firstly, the earth is stationary and doesn't move to anywhere. That knowledge is "old theory" and debunked several times, also by ourselves.

Most part believers accept the "gravity effect" as caused by atmospheric stringency. You may think it as atmospheric pressure. They are not same by phsically but are about same as effective.

In nature, everything pushes others, including atmospher. So when you are on a mountain, there is less atmospher upper side of you and so, it causes less force to down you. So the gravity is less.

In ground level, the atmospher on your upper side is more than the mountain level, so the gravity effect increases. Thats all.

You can explain every type of gravity effects by changing the atmospheric weight/or hight which effect to the object.

PS: I'm an engineer from 20 years.
You are incorrect in your understanding of the role of atmospheric pressure and the measured weight of a object.  An object of constant density and volume will weigh more when the air pressure decreases.  The phenomenon is known as air buoyancy.  There are correction formulas established to accommodate for this effect when doing mass calibrations.  The less dense the object is the more pronounced the weight increase will be as elevation increases.

http://metrology.burtini.ca/grav_air.html

http://www.npl.co.uk/reference/faqs/how-do-i-calculate-and-apply-air-buoyancy-corrections-(faq-mass-and-density)

https://youtu.be/ZrC8rKNufMI

Title: Re: Question from a physicist
Post by: İntikam on May 17, 2017, 09:30:34 AM
Hello everyone. 

I have a question for you all.  I've been through the FAQ and, although the concept of gravity is discussed, I couldn't see any reference to this particular point.

Imagine that you're travelling around with an accurate accelerometer (a device which measures acceleration).  At various places you stop and take a measurement, and after a while start to notice that these measurements differ from each other by a small amount.  This shows that the strength of gravity is different at different places on the planet. 

In classical physics this is well documented and can be explained by a number of different phenomena.  For example, according to Newton's law of gravitation [F=G(Mm)/r^2] if you are at the top of a mountain, gravity should be slightly weaker than if you were at sea level.  Also, the non-uniform mass density of the planet can account for some considerable variation, even if measurements are taken at the same altitude.  In fact, the measurement you take can vary by as much as 0.7% from place to place.

Now, as I understand it (and do please correct me if I've got the wrong idea) you suggest that the flat Earth is being accelerated upwards at a constant 9.8m/s^2.  Surely, if that were the case, the acceleration measured at any point on the planet would be exactly the same.

Thanks for taking the time to read this, and I look forward to hearing what you have to say.  Please note, I'm not here as a troll, I just find the whole topic fascinating.

Thanks!

F

Hello.

Firstly, the earth is stationary and doesn't move to anywhere. That knowledge is "old theory" and debunked several times, also by ourselves.

Most part believers accept the "gravity effect" as caused by atmospheric stringency. You may think it as atmospheric pressure. They are not same by phsically but are about same as effective.

In nature, everything pushes others, including atmospher. So when you are on a mountain, there is less atmospher upper side of you and so, it causes less force to down you. So the gravity is less.

In ground level, the atmospher on your upper side is more than the mountain level, so the gravity effect increases. Thats all.

You can explain every type of gravity effects by changing the atmospheric weight/or hight which effect to the object.

PS: I'm an engineer from 20 years.
You are incorrect in your understanding of the role of atmospheric pressure and the measured weight of a object.  An object of constant density and volume will weigh more when the air pressure decreases.  The phenomenon is known as air buoyancy.  There are correction formulas established to accommodate for this effect when doing mass calibrations.

http://metrology.burtini.ca/grav_air.html

http://www.npl.co.uk/reference/faqs/how-do-i-calculate-and-apply-air-buoyancy-corrections-(faq-mass-and-density)

https://youtu.be/ZrC8rKNufMI

I am correct and your post is completely an hoax. You are already an anti flat earth fascist. You have none of reliablity.
Title: Re: Question from a physicist
Post by: Flatout on May 17, 2017, 10:15:56 AM
Here is some more info on the effects of air pressure and measured weight. All of them show that a decrease in air pressure causes an increase in weight. These are pretty standard engineering calculations​.

Can you back up your claim that weight decreases as air density decreases with any evidence?

https://chem.libretexts.org/Reference/Reference_Tables/Analytic_References/Appendix_09%3A_Correcting_Mass_for_the_Buoyancy_of_Air

https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.npl.co.uk/content/ConMediaFile/1069&ved=0ahUKEwiUptqh1vbTAhWG44MKHRBoCI0QFggpMAA&usg=AFQjCNFFNRwADzn9-EAmadPUyyJGfReT3Q&sig2=mwfXzyyLVj8zMN4wRxZg5g

https://www.google.com/url?sa=t&source=web&rct=j&url=http://radwag.com/pliki/artykuly/buoyancy_force_in_mass_measurement.pdf&ved=0ahUKEwiUptqh1vbTAhWG44MKHRBoCI0QFghOMAY&usg=AFQjCNEK4QPtbTHv4ENIPJ-JT6MgFpQMwg&sig2=f2Sfj_y9sDkM2p2rg_pSXA

https://youtu.be/eOhW-zIwgBQ



Title: Re: Question from a physicist
Post by: fozington on May 17, 2017, 03:50:38 PM
Dear all,

Thank you for the replies that have come in so far, they have been interesting to read.  As a scientist, one universal truth I've come to understand is that answering one question creates innumerable additional questions.  So, I hope you'll permit me to keep this conversation going.  Please try to keep it civil and respectful though, it's important (and extremely interesting) that everyone has a chance to express their opinion. 

I'd like to address some specific points:

Searching "the Wiki" for "gravity" leads to: Universal Acceleration (http://wiki.tfes.org/Universal_Acceleration) where this is particularly relevant to your query
Quote
Tidal Effects
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.
Q: Why does gravity vary with altitude?
A: The moon and stars have a slight gravitational pull.

Thanks, Rabinoz, for finding that for me.  Looks like I must have missed it when I was reading the FAQ.

This point has lead me down a whole path of questions; far too many for this conversation.  I guess the thing that really sticks out to me though is this:  surely that would mean any two locations which have the same altitude would have an identical gravitational force, but this is demonstrably untrue.  Perhaps I'm missing something.

Rabinoz also said:

I still query:
  • How the "gravitation" can exist between "other celestial bodies" and objects on earth
    and not between the massive earth and objects on earth.
  • What explains the variation of gravity with latitude, north and south of the equator.
  • How Einstein's Special Relativity can be accepted,
    but not General Relativity, which reduces to Newton's Laws of Motion and Gravitation.

These are all interesting questions, and I'd like to play devil's advocate here (if you'll pardon the expression) with your first point.  I suppose that, if we assume the flat Earth is an infinite plane of limited depth, then (in classical physics) the main pull of gravity will be in all directions horizontally.  The net effect would be a very slight downward acceleration (caused by the depth of the plane), but nothing like the 9.8m/s^2 we experience.  Hmmm... I'm far from convinced about this, but it's going to be a fun thing to think about later!  Thanks again, Rabinoz, your questions are very interesting and I'd love to hear what others have to say about them.

Most part believers accept the "gravity effect" as caused by atmospheric stringency.

Thanks, İntikam.  Your explanation leads me to two questions/observations:
An object of constant density and volume will weigh more when the air pressure decreases.  The phenomenon is known as air buoyancy.  There are correction formulas established to accommodate for this effect when doing mass calibrations.  The less dense the object is the more pronounced the weight increase will be as elevation increases.

Thanks, Flatout.  The videos you attached were a good example of this phenomenon and I enjoyed watching them.  Now, I'm being a bit pedantic here, but I think I see a problem with this explanation.  Imagine we've got a buoyant object (for example a boat) floating in a fluid medium (like water).  If the density of the fluid increases (maybe you change it for liquid mercury) then the boat will be raised higher, making it appear to have a lower weight.  In fact the weight of the boat remains constant (please note, I'm using the word "weight" as being synonymous with "mass" here.  I understand this is inaccurate, but it keeps things simple.) The apparent mass is what changes here.

So, after saying that, the question I have is this:  In flat Earth theory, what is the difference between weight and mass?  In classical physics weight is the force of an object due to its mass and the acceleration of gravity.  How would it be described in the absence of gravity?

You are already an anti flat earth fascist. You have none of reliablity.

İntikam, please don't say things like that.  It is disrespectful and upsetting.

Thank you all very much for your replies.  As a research physicist I often encounter people with views that are different from my own, and I very much enjoy trying to understand them.  If you have any questions for me, I'll be happy to try to answer them.

F
Title: Re: Question from a physicist
Post by: TomInAustin on May 17, 2017, 06:54:45 PM
Hello everyone. 

I have a question for you all.  I've been through the FAQ and, although the concept of gravity is discussed, I couldn't see any reference to this particular point.

Imagine that you're travelling around with an accurate accelerometer (a device which measures acceleration).  At various places you stop and take a measurement, and after a while start to notice that these measurements differ from each other by a small amount.  This shows that the strength of gravity is different at different places on the planet. 

In classical physics this is well documented and can be explained by a number of different phenomena.  For example, according to Newton's law of gravitation [F=G(Mm)/r^2] if you are at the top of a mountain, gravity should be slightly weaker than if you were at sea level.  Also, the non-uniform mass density of the planet can account for some considerable variation, even if measurements are taken at the same altitude.  In fact, the measurement you take can vary by as much as 0.7% from place to place.

Now, as I understand it (and do please correct me if I've got the wrong idea) you suggest that the flat Earth is being accelerated upwards at a constant 9.8m/s^2.  Surely, if that were the case, the acceleration measured at any point on the planet would be exactly the same.

Thanks for taking the time to read this, and I look forward to hearing what you have to say.  Please note, I'm not here as a troll, I just find the whole topic fascinating.

Thanks!

F

Hello.

Firstly, the earth is stationary and doesn't move to anywhere. That knowledge is "old theory" and debunked several times, also by ourselves.

Most part believers accept the "gravity effect" as caused by atmospheric stringency. You may think it as atmospheric pressure. They are not same by phsically but are about same as effective.

In nature, everything pushes others, including atmospher. So when you are on a mountain, there is less atmospher upper side of you and so, it causes less force to down you. So the gravity is less.

In ground level, the atmospher on your upper side is more than the mountain level, so the gravity effect increases. Thats all.

You can explain every type of gravity effects by changing the atmospheric weight/or hight which effect to the object.

PS: I'm an engineer from 20 years.

Then why does an object not float in a vacuum?  Surely you took a few physics courses in your engineering curriculum?
Title: Re: Question from a physicist
Post by: 3DGeek on May 17, 2017, 09:46:16 PM
So from what I've been reading, there are at least three FE theories for why things fall to the floor when you drop them? (What RE calls "gravity").

1) The Earth is accelerating upwards at 9.8 m/s/s.
2) That the air presses down on things to make them fall.
3) That there actually is gravity (like in RE) but the earth is infinite in extent.

Then maybe some people believe combinations of these - so accelerating upwards AND air pressing downwards...or that AND that the sun, moon and stars do have actual gravity and pull upwards to make things lighter on mountain tops.

My problem is that I don't see how any of these - in any combination - explains the observation that gravity is less at the equator than at the poles.

It's very difficult to discuss FE theories when there are so many of them, and they are (frankly) contradictory.

It would be nice to have some kind of clarification of all of them.  The Wiki doesn't really lay them all out clearly.
Title: Re: Question from a physicist
Post by: Flatout on May 17, 2017, 10:27:52 PM
The effects of gravity are also different when objects are in motion going east vs West and in motion at different latitudes.
Title: Re: Question from a physicist
Post by: 3DGeek on May 18, 2017, 12:28:34 PM
The effects of gravity are also different when objects are in motion going east vs West and in motion at different latitudes.

Oh!?   That's odd.   What is the cause and effect of that one?
Title: Re: Question from a physicist
Post by: Flatout on May 18, 2017, 12:46:08 PM
The effects of gravity are also different when objects are in motion going east vs West and in motion at different latitudes.

Oh!?   That's odd.   What is the cause and effect of that one?
When traveling east your total velocity (velocity plus earth spin) is greater than when traveling due west (earth spin minus velocity).   The centripetal acceleration is greater when traveling east resulting in lower measured weight. It's called the Eotvos Effect.

 http://www.cleonis.nl/physics/phys256/eotvos.php

Title: Re: Question from a physicist
Post by: 3DGeek on May 18, 2017, 03:54:06 PM

When traveling east your total velocity (velocity plus earth spin) is greater than when traveling due west (earth spin minus velocity).   The centripetal acceleration is greater when traveling east resulting in lower measured weight. It's called the Eotvos Effect.

 http://www.cleonis.nl/physics/phys256/eotvos.php

Oh - yeah - I'd forgotten about that result.  Weird.  Makes sense in RE - but less so in FE.

It's almost like the laws of FE physics cunningly conspire to make it seem like the Earth is round!
Title: Re: Question from a physicist
Post by: Pete Svarrior on May 18, 2017, 05:00:04 PM
I still query:
  • How the "gravitation" can exist between "other celestial bodies" and objects on earth
    and not between the massive earth and objects on earth.
You assume without evidence that there is a correlation between mass and gravitational pull.

  • How Einstein's Special Relativity can be accepted,
    but not General Relativity, which reduces to Newton's Laws of Motion and Gravitation.
Given that the two are entirely separate, I don't see why you would necessarily expect anyone to either accept or reject both. It's like saying that all vegetarians must be left-wingers.
Title: Re: Question from a physicist
Post by: Flatout on May 19, 2017, 12:47:28 PM
    I still query:
    • How the "gravitation" can exist between "other celestial bodies" and objects on earth
      and not between the massive earth and objects on earth.
    You assume without evidence that there is a correlation between mass and gravitational pull.
    You assume that science just makes stuff up.  We have been doing measured mass attraction experiments since the mid 1800's.   Our present understanding of gravity and mass were derived from those experiments. 
      https://youtu.be/Ym6nlwvQZnE[/list]
    Title: Re: Question from a physicist
    Post by: Loránd Eötvös on April 22, 2018, 03:05:22 AM
    According to RE physics, they should take hours to collide. The fact that it happens rapidly proves that this isn't the case.
    Title: Re: Question from a physicist
    Post by: Macarios on April 22, 2018, 06:33:00 AM
    According to RE physics, they should take hours to collide. The fact that it happens rapidly proves that this isn't the case.

    How many hours?
    0.1?

    If we estimate bigger ball to be 10 centimeters in diameter, it is 5 cm in radius.
    Volume of 523.6 cm3 would have mass of 5.94 kg.
    Acceleration of such ball at the distance of 0.1 meter will be a = GM/d2 = 39.6e-9 m/s2
    (G is gravitational constant, 6.67408e-11)
    Considering that from the other side another ball of the same mass pulls together, total acceleration will be 79.2e-9 m/s2

    Now we can calculate how many hours would take for smaller balls to move for 1 cm.
    If d = at2 / 2 then t = SQRT(2d/a) = 502.5 seconds, or little over 8 minutes.

    Ok, I was wrong.
    It will not be 0.1 hour, it will be 0.14 hours.
    Would you expect people to wait, or you'd rather speed up the video?
    Would you wait 8 minutes to see smaller ball move?

    Ofcourse, you don't have to trust anything at all.
    You can always hang your own balls or bricks and measure.
    There you can wait as much as accuracy needs.

    Author of the video knew that anyone can repeat the experiment and see the result.
    After all, that's how "independent confirmation" works in every discipline.
    Title: Re: Question from a physicist
    Post by: AATW on April 22, 2018, 07:36:58 AM
    I see this thread followed the usual "story arc" on here,
    Some wild, baseless FE assertions with no evidence provided
    Some explanations from RE
    FE claiming there is no evidence for those explanations
    RE posting some actual experiments demonstrating the explanations
    FE either calling them fake or, in this instance, willfully misunderstanding them.
    RE explaining them more clearly.
    End of thread. No further rebuttals by FE or any conceding of ground by FE.
    Rinse and repeat.

    This is another experiment which can be easily repeated, if FE is about empiricism then why not have a go?
    Title: Re: Question from a physicist
    Post by: Tontogary on April 22, 2018, 11:08:04 AM
    Objects displace air, and its the displacement of the air that causes the object to weight less in air than a vacuum.

    The idea is similar, and the principle is the same as Archimedes principle for floating objects, or submerged objects.

    That is that a floating object displaces the same mass of liquid as its own mass when afloat. Also if it sinks, it means the mass of the liquid it displaces is less than the mass of the object.

    So in very basic terms, if an object of 1 cubic meter has a mass of less than 1Mt then it will float, if it has a mass of more than 1 Mt then it sinks, but in doing so will weigh what it did before being immersed, minus 1MT. 1 cubic metre of fresh water weighs 1Mt.

    Now substitute air for water, and you have an understanding that an object weighs what it does in no air MINUS the mass of the air it displaces.

    Therefore an object will weigh more in a Vacuum than it does in air.

    I am hoping people agree basic principles of floatation here, as you can see it all the time. If not so there would be no ships, boats, and you wouldn’t be able to float in your pool, you would sink!
    Title: Re: Question from a physicist
    Post by: Sturmlied on April 22, 2018, 01:54:58 PM
    I am correct and your post is completely an hoax. You are already an anti flat earth fascist. You have none of reliablity.

    You posted an argument and someone posted a counter argument, instead of addressing the counter argument you resorted to ad hominem attacks and you think that this supports your argument?

    I see this thread followed the usual "story arc" on here,
    Some wild, baseless FE assertions with no evidence provided
    Some explanations from RE
    FE claiming there is no evidence for those explanations
    RE posting some actual experiments demonstrating the explanations
    FE either calling them fake or, in this instance, willfully misunderstanding them.
    RE explaining them more clearly.
    End of thread. No further rebuttals by FE or any conceding of ground by FE.
    Rinse and repeat.

    This is another experiment which can be easily repeated, if FE is about empiricism then why not have a go?

    Is this not always the case? I am reading forum like this on and off for a while now and this pattern is staggeringly obvious.
    Title: Re: Question from a physicist
    Post by: Obviously on April 23, 2018, 06:27:08 AM
    Given that the two are entirely separate, I don't see why you would necessarily expect anyone to either accept or reject both. It's like saying that all vegetarians must be left-wingers.

    Special Relativity is a subset of General Relativity, so this is not at all like all vegetarians being left-wingers (although there does seem to be a pattern there...), but nice try )
    Title: Re: Question from a physicist
    Post by: Westprog on April 23, 2018, 06:58:19 AM
    I am correct and your post is completely an hoax. You are already an anti flat earth fascist. You have none of reliablity.

    I find this fascinating. Why claim to be an engineer and not be familiar with Archimedes Principle, one of the most famous discoveries in physics and something that it's impossible to avoid if you've taken any kind of engineering training?

    It's very easy to verify that something weighs less when immersed in a dense medium. It's the reason that we can have ships made out of iron. Or is that a hoax too?

    As always, we see a simple experiment shown here, and it's dismissed as being propaganda. Will this experiment be repeated by any FE advocates to demonstrate that it's a fraud? Of course it isn't. If they are eventually forced to accept that the experiment (repeated in many forms over many years) is actually real, then it will suddenly become peripheral.

    I note as an aside, as I come off another lengthy ban, that the above post didn't garner as much as a warning.

    Title: Re: Question from a physicist
    Post by: hexagon on April 23, 2018, 12:43:54 PM
    The whole universal acceleration idea is a good example of who people come to wrong conclusion if they do not have a real understanding of the expression they using. This idea is based on the equivalence principle, that, in very simple words, says, that you cannot distinguish the effect of a gravitational field from that of a constant acceleration. But this was never supposed to be valid for the gravitational field of a whole planet. It is only valid for homogeneous gravitational field, but the field of a planet is not homogeneous it changes with the distance from the center of the planet. So you can find a certain non-inertial system for each point around the planet, but they're all different from each other depending on their distance from the center. There's no universal non-inertial system that includes the whole planet and everything above it, therefor there is no universal acceleration.       
    Title: Re: Question from a physicist
    Post by: Westprog on April 23, 2018, 04:24:34 PM
    The whole universal acceleration idea is a good example of who people come to wrong conclusion if they do not have a real understanding of the expression they using. This idea is based on the equivalence principle, that, in very simple words, says, that you cannot distinguish the effect of a gravitational field from that of a constant acceleration. But this was never supposed to be valid for the gravitational field of a whole planet. It is only valid for homogeneous gravitational field, but the field of a planet is not homogeneous it changes with the distance from the center of the planet. So you can find a certain non-inertial system for each point around the planet, but they're all different from each other depending on their distance from the center. There's no universal non-inertial system that includes the whole planet and everything above it, therefor there is no universal acceleration.     

    Aside from the evidence which clearly shows that the Earth is not accelerating, imagine the effect of sufficient acceleration to maintain gravity for 6,000 years*. Whether one accepts special relativity, or allows velocities beyond the speed of light (and who knows what any given flat Earther at any given time will believe), the Earth will clearly be moving PDQ. What happens if it hits something? The velocity of the Earth would be such that hitting a speck of dust would cause a massive explosion.

    Of course, this won't be an issue because the entire universe is accelerating through... actually, what is it accelerating through? We can never know, because everything is glued to the celestial dome. A completely empty infinite tube, without beginning or end. We must hope, at least, because if it ever hits something, that will be pretty disastrous.
    Title: Re: Question from a physicist
    Post by: hexagon on April 24, 2018, 12:14:35 PM
    The problem is not the sufficient acceleration, it's the force that leads to this acceleration. If you take relativity theory serious, the mass of the earth would continuously increase with its speed. If the force is constant, according to F = m*a, the acceleration is inverse proportional to the mass. But if the acceleration is constant, the force has to increase in the same way as the mass. And with this the energy that is needed maintain the force is also increasing... And now think about how fast the earth would be already, how large the mass would be and therefore the force and therefore the energy...   
    Title: Re: Question from a physicist
    Post by: Stagiri on April 24, 2018, 02:46:57 PM
    The problem is not the sufficient acceleration, it's the force that leads to this acceleration. If you take relativity theory serious, the mass of the earth would continuously increase with its speed. If the force is constant, according to F = m*a, the acceleration is inverse proportional to the mass. But if the acceleration is constant, the force has to increase in the same way as the mass. And with this the energy that is needed maintain the force is also increasing... And now think about how fast the earth would be already, how large the mass would be and therefore the force and therefore the energy...

    From our perspective (and due to relativity), the force (and the mass) would remain the same.
    Title: Re: Question from a physicist
    Post by: AATW on April 24, 2018, 03:08:48 PM
    The problem is not the sufficient acceleration, it's the force that leads to this acceleration. If you take relativity theory serious, the mass of the earth would continuously increase with its speed. If the force is constant, according to F = m*a, the acceleration is inverse proportional to the mass. But if the acceleration is constant, the force has to increase in the same way as the mass. And with this the energy that is needed maintain the force is also increasing... And now think about how fast the earth would be already, how large the mass would be and therefore the force and therefore the energy...

    From our perspective (and due to relativity), the force (and the mass) would remain the same.
    Even so, that is still a metric shit-ton of force though to accelerate a mass the size of the earth at 9.8m/s/s
    Title: Re: Question from a physicist
    Post by: hexagon on April 24, 2018, 03:35:24 PM
    Our perspective is not relevant, as we are inside the accelerated system. The force is acting on the entire system, you have to look at it from the inertia system where everything in embedded inside. And it goes beyond my imagination how this inertia system should look like in which something like our whole visible universe is accelerated at near light speed with a therefore almost infinite force along a straight line...   
    Title: Re: Question from a physicist
    Post by: 9 out of 10 doctors agree on April 24, 2018, 05:01:36 PM
    The problem is not the sufficient acceleration, it's the force that leads to this acceleration. If you take relativity theory serious, the mass of the earth would continuously increase with its speed. If the force is constant, according to F = m*a, the acceleration is inverse proportional to the mass. But if the acceleration is constant, the force has to increase in the same way as the mass. And with this the energy that is needed maintain the force is also increasing... And now think about how fast the earth would be already, how large the mass would be and therefore the force and therefore the energy...

    From our perspective (and due to relativity), the force (and the mass) would remain the same.
    Even so, that is still a metric shit-ton of force though to accelerate a mass the size of the earth at 9.8m/s/s
    Just a comparison: if the Earth was propelled by rocket engines, then the least amount of fuel needed to maintain Earth gravity for the 6000 years since God allegedly created it would be around 102700 kilograms. Plus or minus a few dozen orders of magnitude.
    Title: Re: Question from a physicist
    Post by: AATW on April 24, 2018, 05:12:12 PM
    The problem is not the sufficient acceleration, it's the force that leads to this acceleration. If you take relativity theory serious, the mass of the earth would continuously increase with its speed. If the force is constant, according to F = m*a, the acceleration is inverse proportional to the mass. But if the acceleration is constant, the force has to increase in the same way as the mass. And with this the energy that is needed maintain the force is also increasing... And now think about how fast the earth would be already, how large the mass would be and therefore the force and therefore the energy...

    From our perspective (and due to relativity), the force (and the mass) would remain the same.
    Even so, that is still a metric shit-ton of force though to accelerate a mass the size of the earth at 9.8m/s/s
    Just a comparison: if the Earth was propelled by rocket engines, then the least amount of fuel needed to maintain Earth gravity for the 6000 years since God allegedly created it would be around 102700 kilograms. Plus or minus a few dozen orders of magnitude.
    I think you'll find that 102700 kilograms is exactly 1 metric shit-ton.
    I rest my case.

    I always find it odd that some people sniff at gravity because it's not fully understood and yet quite happily accept that an INCREDIBLE amount of "dark energy" would have to be accelerating the earth upwards with no explanation as to how that might work and where all that energy is coming from.
    Title: Re: Question from a physicist
    Post by: Stagiri on April 24, 2018, 05:17:44 PM
    (...) I always find it odd that some people sniff at gravity because it's not fully understood (...)

    Wait, I've thought that we understand gravity very well... What did I miss?
    Title: Re: Question from a physicist
    Post by: AATW on April 24, 2018, 05:23:17 PM
    (...) I always find it odd that some people sniff at gravity because it's not fully understood (...)

    Wait, I've thought that we understand gravity very well... What did I miss?
    I've seen Tom muttering about gravitons which are admittedly theoretical.
    I thought there were still some things not well understood about it but this is a bit above my level of understanding of physics tbh.
    Title: Re: Question from a physicist
    Post by: Stagiri on April 24, 2018, 05:32:23 PM
    (...) I always find it odd that some people sniff at gravity because it's not fully understood (...)

    Wait, I've thought that we understand gravity very well... What did I miss?
    I've seen Tom muttering about gravitons which are admittedly theoretical.
    I thought there were still some things not well understood about it but this is a bit above my level of understanding of physics tbh.

    The only thing we don't understand is how gravity behaves in the realm of quantum mechanics (that's where gravitons, the hypothetical elementary particles that mediate gravity, come from). However, the rest is very well understood (thanks to Sir Newton and Mr. Einstein).

    EDIT: some hypotheses uniting gravity and quantum mechanics: string theory, superstring theory, M-theory, Verlinde's entropic gravity, ...
    Title: Re: Question from a physicist
    Post by: Westprog on April 24, 2018, 07:19:56 PM

    I thought there were still some things not well understood about it but this is a bit above my level of understanding of physics tbh.

    Nothing is fully understood in physics. Full understanding is never possible. What we do is produce a model which seems to explain things, and to make predictions. The predictions of the Newtonian model worked very well for a very long time, and are still accurate for most purposes. The Einsteinian model turns out to very slightly better fit observation.
    Title: Re: Question from a physicist
    Post by: JohnAdams1145 on April 25, 2018, 05:57:21 AM
    The problem is not the sufficient acceleration, it's the force that leads to this acceleration. If you take relativity theory serious, the mass of the earth would continuously increase with its speed. If the force is constant, according to F = m*a, the acceleration is inverse proportional to the mass. But if the acceleration is constant, the force has to increase in the same way as the mass. And with this the energy that is needed maintain the force is also increasing... And now think about how fast the earth would be already, how large the mass would be and therefore the force and therefore the energy...

    From our perspective (and due to relativity), the force (and the mass) would remain the same.
    Even so, that is still a metric shit-ton of force though to accelerate a mass the size of the earth at 9.8m/s/s
    Just a comparison: if the Earth was propelled by rocket engines, then the least amount of fuel needed to maintain Earth gravity for the 6000 years since God allegedly created it would be around 102700 kilograms. Plus or minus a few dozen orders of magnitude.
    I think you'll find that 102700 kilograms is exactly 1 metric shit-ton.
    I rest my case.

    I always find it odd that some people sniff at gravity because it's not fully understood and yet quite happily accept that an INCREDIBLE amount of "dark energy" would have to be accelerating the earth upwards with no explanation as to how that might work and where all that energy is coming from.

    The force argument for accelerating the Earth doesn't work because of what FE predicts: the physical effects of UA disappear as you get away from Earth. So essentially what they're posing (in an unnecessarily roundabout way) is that the force that pulls things to the Flat Earth's surface is magically there. Of course, it doesn't help that they refuse to actually make a position on what "gravitation" depends on (and how it's modeled) instead of just stuffing it in there as a correction to make things align with reality; in other words, gravitation just magically makes their model work by applying just the right amount of force everywhere. Sounds like moving the goalposts. And if you think this is unfair treatment of FE, then I challenge you to point me to a single place in this forum/wiki where there is an empirically-verified equation for describing gravitational force. There isn't one. It's just inserted to patch the horribly leaky UA.

    Nobody has also posed the question of why the planets and stars are spherical if this so-called Universal Acceleration is shielded by massive objects (as opposed to some contrived special characteristic of Earth). If UA were the result of mass-shielding, we'd expect the planets/stars to be significantly flattened as there would be an asymmetric compressive force on it, much as we see on Earth today.

    To clarify why the energy/force arguments do not work, I'll contrive a scenario. You jump into your car and drive in a perfectly straight line. By relativity, your house is moving in the opposite direction in your reference frame. Therefore, your house has a tremendous amount of kinetic energy that seems counterintuitive. Energy is not invariant across reference frames, but it is still conserved within the same frame. Of course, the previous reasoning doesn't exactly parallel this, as it deals with acceleration, which is considered non-relative even in special relativity. Nevertheless, general relativity treats it differently.
    Title: Re: Question from a physicist
    Post by: Macarios on April 25, 2018, 08:00:06 AM
    The force argument for accelerating the Earth doesn't work because of what FE predicts: the physical effects of UA disappear as you get away from Earth. So essentially what they're posing (in an unnecessarily roundabout way) is that the force that pulls things to the Flat Earth's surface is magically there.

    As far as I could understand the Flat Earthers, "there is no escape".
    There's nothing left or right from Ice Wall, everything that exists is above the ground (land or sea).
    At whichever altitude object is, Earth will catch up by own acceleration.
    In the case of free fall they just switch reference point to falling object, claiming that Earth actualy accelerates towards objects.

    First of all, not all Flat Earthers support UA hypothesis.
    Second, the main problem with UA is uniformity.
    Earth will either have constant g at any point, or get heavily distorted very quickly in very short time.

    And we know very well that g is not only variable with latitude, but with altitude as well.
    What Flat Earthers are trying to do is to sweep under the carpet all those differences in g all over the place, and to skip the fact that g depends on distance from the Earth's center.
    (And slightly from the local density of the ground.)

    I already gave the example of different acceleration of poles and equator.
    In only 30 minutes, if initial speed was zero, UA would make poles (North pole and Ice Wall) higher than the Equator for d = at2 / 2, where a = gpole - gequator = 9.832 - 9.78 = 0.052 m/s2.
    So, d = 0.052 * 18002 / 2 = 84 240 m.

    Does anyone see mountain 84 km high on North pole?

    But let me repeat: not all FE-rs support UA.
    Smarter ones are aware of two things:
    - if Earth accelerates, it has to be "through something" which will allow existence of the Universe
    - Universal Accelerator directly contradicts with "static, unmovable, firm" Earth.

    Complaining about "mind-blowing 30 km/s around Sun" and "outrageous 230 km/s around galactic core" is counterproductive if your alternative is "lousy 99.99% of light speed (300 000 km/s)".
    Title: Re: Question from a physicist
    Post by: Tumeni on April 25, 2018, 08:02:01 AM
    Wait, I've thought that we understand gravity very well... What did I miss?

    Most every flattie on YouTube, who thinks gravity is "just an unproven theory"
    Title: Re: Question from a physicist
    Post by: hexagon on April 25, 2018, 08:04:44 AM
    It is not the house, it is the whole earth that is moving relative to you. But in any case the example is not valid, you need the energy to accelerate against the reference system of the earth therefore the two reference frames are not equivalent. As soon as you stop to accelerate (and assuming there are no losses due to friction, and so on) there is no more energy transfer needed. The same if you stop the car.

    You can also look at everything from a reference frame outside the earth, also in that case you would see, that only the car is accelerating, not the earth relative to the car.

    Anyway, you cannot refer to the equivalence principle and claim because of that you can replace gravity by an acceleration without taking the other consequences of general relativity into account.       
    Title: Re: Question from a physicist
    Post by: JohnAdams1145 on April 25, 2018, 10:56:14 AM
    Macarios, as far as I know, the FE people believe that they have addressed the different perceived accelerations around the Earth.

    Their idea, and I may be a little wrong on it, is that UA + "celestial gravitation" (a leaky patch without even the slightest of quantifications) combine to produce the effects of gravity on Earth. So that's what keeps the Earth in one piece. The variations in altitude are caused by a reduction of the "shielding" effect, and the variations in latitude are magically fixed by a specially-designed "celestial gravitation" force.

    I believe I heard from Parsifal that the entire universe accelerates along with the Earth (by the invisible dark energy nonsense); otherwise, we'd see micrometeorites smashing into us at relativistic speeds and extreme length contraction amongst the stars and planets. However, the magical "shielding" effect of the Earth (and presumably other large masses) makes people on the surface of the Earth a special case that need to be accelerated via a normal force, making us feel weight.

    hexagon,
    I'm aware that the particular example involving a house and a car does not completely justify the particular rebuttal I made; it just provides some intuition for it. Energy is not invariant across reference frames, and therefore any energy arguments made against UA in the particular invocation that I describe it in are flawed. Instead of imagining the car accelerating, you can just imagine that it started out at a certain speed. Clearly, the kinetic energies are different in different reference frames, both of which may be inertial (and therefore not preferred).


    Effectively, I can describe "gravitation" as a magical force that exists only on the surfaces and interiors of planets. In the case of Earth, it's a magical force normal to the surface that conforms exactly to reality. My model posits that it will read on a scale exactly what it predicts. While my model seems like a piece of garbage pulled from the machinations of my mind, you should note that it is just as valid as the UA explanation because:
    1. It makes assumptions of about the same strength. (UA assumes celestial gravitation, I assume a gravitation that just works)
    2. It makes exactly the same predictions in all cases. (UA says celestial gravitation fixes the variations in gravity; I say my gravitational force is completely correct in the first place).

    And, so, you can't really falsify UA unless you actually disprove the assumptions (show that the Earth is not flat). Of course, if FE were willing to come up with equations/laws governing the application of celestial gravitation, then my model would be assuming far more, and we could indeed falsify UA by checking measurements of the celestial gravitation.

    Of course, we can simply reject UA on the grounds that the assumptions make it effectively unfalsifiable and useless in terms of predictive power, and recognize that the idea that "gravity is complicated so it can't exist" is inherently hypocritical.
    Title: Re: Question from a physicist
    Post by: hexagon on April 25, 2018, 11:46:06 AM
    The fundamental problem with equivalence principle is, that it's only valid for homogeneous gravitational fields, which are equivalent to a constant acceleration. Real gravitational fields, i.e. fields originating in mass, are not homogeneous, and can only be replaced locally by an acceleration. The whole concept was introduced by Einstein to allow the use of special relativity at least on a local scale in a gravitational field before he invented the concept of general relativity.

    Therefor inherently you have to come up with additional explanations outside the framework of general relativity if you want to use a concept like universal acceleration.

    And whatever is pushing the earth in this concept, feels an increasing mass and has therefor to push harder to keep the acceleration constant. And any force needs energy and an infinite force needs infinite energy.

    And, finally, it is not a god idea to use special relativity examples (constant velocity) to explain general relativity (constant acceleration) scenarios. It is misleading.             
    Title: Re: Question from a physicist
    Post by: TomInAustin on April 25, 2018, 06:50:54 PM
    The fundamental problem with equivalence principle is, that it's only valid for homogeneous gravitational fields, which are equivalent to a constant acceleration. Real gravitational fields, i.e. fields originating in mass, are not homogeneous, and can only be replaced locally by an acceleration. The whole concept was introduced by Einstein to allow the use of special relativity at least on a local scale in a gravitational field before he invented the concept of general relativity.

    Therefor inherently you have to come up with additional explanations outside the framework of general relativity if you want to use a concept like universal acceleration.

    And whatever is pushing the earth in this concept, feels an increasing mass and has therefor to push harder to keep the acceleration constant. And any force needs energy and an infinite force needs infinite energy.

    And, finally, it is not a god idea to use special relativity examples (constant velocity) to explain general relativity (constant acceleration) scenarios. It is misleading.           

    More questions about this mysterious force that accelerates the earth.   What is it?  What is the source?  What is the medium the earth is in?  Is the force applied equally or is the earth structurally sound to have a central point the force is applied to?  Is it pushing or pulling?  Will it ever run out of energy?  Will the earth ever run out of space to accelerate in?
    Title: Re: Question from a physicist
    Post by: Stagiri on April 25, 2018, 07:43:25 PM
    (..)
    And whatever is pushing the earth in this concept, feels an increasing mass and has therefor to push harder to keep the acceleration constant. And any force needs energy and an infinite force needs infinite energy.
    (...)         

    Well, due to relativity, it's a bit more complicated.
    From the perspective of an outside observer, as the speed of the Earth would approach the speed of light its acceleration would signifantly decrease. Thus the force/the energy would "only" approach infinity.
    However, from our perspective, the acceleration wouldn't change and neither would the mass/the force/the energy. The FES actually got this right.

    Nevertheless, UA cannot explain the non-homogeneity, such as the Eötvös effect and so on.
    Title: Re: Question from a physicist
    Post by: Macarios on April 25, 2018, 09:11:10 PM
    Macarios, as far as I know, the FE people believe that they have addressed the different perceived accelerations around the Earth.

    Their idea, and I may be a little wrong on it, is that UA + "celestial gravitation" (a leaky patch without even the slightest of quantifications) combine to produce the effects of gravity on Earth. So that's what keeps the Earth in one piece. The variations in altitude are caused by a reduction of the "shielding" effect, and the variations in latitude are magically fixed by a specially-designed "celestial gravitation" force.

    Speaking of Celestial Gravitation, it inflicts force on what?
    On objects with mass?
    Or on objects selected by "celestial imaginary friend"?

    We also have this:
    Quote
    Acceleration at the top of Mount Everest is 9.77015 m/s2.
    Acceleration in Tampa is 9.79736 m/s2.
    (from: http://www.wolframalpha.com/widgets/view.jsp?id=e856809e0d522d3153e2e7e8ec263bf2)
    Mount Everest is at 27.98 degrees north, at 8848 meters above sea level.
    Tampa, FL is also 27.98 degrees north, at 1 meter above sea level.

    Moving closer to the source of the celestial gravitation above Mount Everest for 8847 meters makes the acceleration lower 1.002812649 times.
    It means the distance was changed SQRT(1.002812649) = 1.001405337 times. Let's call it k.
    Since (D-1) = (D-8848)*k it makes D = (8848*k-1) / (k-1) = 6 304 135 m from the sea level (6 305 km).
    This is consistent with height of the Sun to be 5005 km.

    On North pole and on Ice Wall g is 9.832 m/s2,
    Knowing that, we can calculate the distance from celestial source to be 6304135 * SQRT(9.832 / 9.79736) = 6 315 270 m.
    6 315 270 - 6 304 135 = 11 135
    It means the North pole and Ice Wall are both 11 135 meters below sea level.
    It is somewhere around the bottom of Mariana Trench.

    Ok, now we have another question here.
    Since the "dome rotates" above the Earth's surface, whatever configuration it has, it must be circular, similar to vinyl record, or Fresnel lens.
    For example, above Mount Everest must be the same distance regardless of the angle of the "dome" above the Earth.
    Same goes for Aconcagua, Rocky Mountains, Appalachians, Alps, Carpathians, and the rest of the Earth's surface.

    However, instead of poles (North pole and Ice Wall) being at the depth of Mariana trench, center and edges of dome can be for those 11 135 m higher than the part above equator.
    Now imagine simultaneous sky observation from multiple locations, permanently done not only by professional astronomers, but amateurs too.

    About "Universe is accelerating with Earth", the claim only redefines "Universe" into "Local Universe".
    (Changes focus of the meaning of the word.)
    It doesn't eliminate the question "through what?".
    Title: Re: Question from a physicist
    Post by: hexagon on April 26, 2018, 08:29:12 AM
    (..)
    And whatever is pushing the earth in this concept, feels an increasing mass and has therefor to push harder to keep the acceleration constant. And any force needs energy and an infinite force needs infinite energy.
    (...)         

    Well, due to relativity, it's a bit more complicated.
    From the perspective of an outside observer, as the speed of the Earth would approach the speed of light its acceleration would signifantly decrease. Thus the force/the energy would "only" approach infinity.
    However, from our perspective, the acceleration wouldn't change and neither would the mass/the force/the energy. The FES actually got this right.

    Nevertheless, UA cannot explain the non-homogeneity, such as the Eötvös effect and so on.

    I think I already mentioned, that of course from the earths point of view, you would not notice the changes, but if you think about the plausibility of the whole concept of universal acceleration, you have to look from the reference frame in which you see the force acting on the earth. And an observer in that reference frame would see an almost infinite force acting on the earth. And that doesn't make any sense at all.

    No one of them got it right, cause they're only looking at half of the story.

    That would be like saying I don't care of the energy consumption of a big particle accelerator cause the particles don't feel their increase of mass. From the point of view of the accelerator the energy consumption is real. The same is true from the point of view of whatever is pushing the earth... 
    Title: Re: Question from a physicist
    Post by: JohnAdams1145 on April 27, 2018, 09:54:10 PM
    (..)
    And whatever is pushing the earth in this concept, feels an increasing mass and has therefor to push harder to keep the acceleration constant. And any force needs energy and an infinite force needs infinite energy.
    (...)         

    Well, due to relativity, it's a bit more complicated.
    From the perspective of an outside observer, as the speed of the Earth would approach the speed of light its acceleration would signifantly decrease. Thus the force/the energy would "only" approach infinity.
    However, from our perspective, the acceleration wouldn't change and neither would the mass/the force/the energy. The FES actually got this right.

    Nevertheless, UA cannot explain the non-homogeneity, such as the Eötvös effect and so on.

    I think I already mentioned, that of course from the earths point of view, you would not notice the changes, but if you think about the plausibility of the whole concept of universal acceleration, you have to look from the reference frame in which you see the force acting on the earth. And an observer in that reference frame would see an almost infinite force acting on the earth. And that doesn't make any sense at all.

    No one of them got it right, cause they're only looking at half of the story.

    That would be like saying I don't care of the energy consumption of a big particle accelerator cause the particles don't feel their increase of mass. From the point of view of the accelerator the energy consumption is real. The same is true from the point of view of whatever is pushing the earth...

    The problem is that FES asserts that there isn't a reference frame where you can actually see the truly massive Earth's acceleration, since if you sit "behind" Earth, you're not shielded as much from UA so you travel along with it.

    But as I think about it more, perhaps when you're in free fall, you may be able to make the energy argument, since it's really hard to argue that the ground is accelerating toward you (for what reason?). I'll have to read up more on general relativity for that one, but I believe that if you're in free fall, your proper acceleration is 0, but the ground is moving toward you at an increasing rate, so you must conclude that you're under the influence of gravity or that the ground is magically accelerating toward you.