The Flat Earth Society
Flat Earth Discussion Boards => Flat Earth Theory => Topic started by: fisherman on October 08, 2020, 04:18:35 PM
-
The reason I ask is because UA rises and falls (pun intended) on the equivalence principle, but the equivalence principle logically leads (at least according to Einstein) to the gravitational and inertial effects of falling bodies as determined by spacetime...or as he calls it in the quote below the "g-field"
Inertia and gravity are phenomena identical in nature. From this and from the special theory of relativity it follows necessarily that the symmetric "fundamental tensor" determines the metric properties of space, the inertial behavior of bodies in space, as well as the gravitational effects. We shall call the state of space which is described by this fundamental tensor, the "g-field"
https://einsteinpapers.press.princeton.edu/vol7-trans/49?highlightText=metric
-
In GR the surface of the earth is accelerating upwards through spacetime. It is Einstein's way of getting the upwardly accelerating Earth concept to work in RE, since experimental evidence and lack of inertial resistance shows that the Earth is accelerating upwards and that it is not an invisible phenomenon pulling bodies down to the Earth.
Gravity: A Very Short Introduction (https://books.google.com/books?id=FFQjDgAAQBAJ&pg=PT34&lpg=PT34&dq=%22earth+pushing+you%22&source=bl&ots=MV9ROmx5Eu&sig=ACfU3U17gR2YnIJbxFhEuRhKz2cR-mVBgQ&hl=en&sa=X&ved=2ahUKEwjaoLf6xMHiAhUPpFkKHTqqAMwQ6AEwDXoECB0QAQ#v=onepage&q=%22earth%20pushing%20you%22&f=false) by Cosmologist Timothy Clifton:
“ Consider a skydiver jumping out of an airplane. The skydiver falls freely, up to the effects of air resistance. According to Einstein, the skydiver's path is the straightest line possible through the curved space-time around the Earth. From the skydiver's perspective this seems quite natural. Except for the air rushing past her, the skydiver feels no perturbing forces at all. In fact, if it weren't for the air resistance, she would experience weightlessness in the same way that an astronaut does in orbit. The only reason we think the skydiver is accelerating is because we are used to using the surface of the Earth as our frame of reference. If we free ourselves from this convention, then we have no reason to think the skydiver is accelerating at all.
Now consider yourself on the ground, looking up at the falling daredevil. Normally, your intuitive description of your own motion would be that you are stationary. But again this is only because of our slavish regard to the Earth as the arbiter of what is at rest and what is moving. Free yourself from this prison, and you realize that you are, in fact, accelerating. You feel a force on the soles of your feet that pushes you upwards, in the same way that you would if you were in a lift that accelerated upwards very quickly. In Einstein's picture there is no difference between your experience sanding on Earth and your experience in the lift. In both situations you are accelerating upwards. In the latter situation it is the lift that is responsible for your acceleration. In the former, it is the fact that the Earth is solid that pushes you upwards through space-time, knocking you off your free-fall trajectory. That the surface of the Earth can accelerate upwards at every point on its surface, and remain as a solid object, is because it exists in a curved space-time and not in a flat space.
With this change in perspective the true nature of gravity becomes apparent. The free falling skydiver is brought to Earth because the space-time through which she falls is curved. It is not an external force that tugs her downwards, but her own natural motion through a curved space. On the other hand, as a person standing on the ground, the pressure you feel on the soles of your feet is due to the rigidity of the Earth pushing you upwards. Again, there is no external force pulling you to Earth. It is only the electrostatic forces in the rocks below your feet that keep the ground rigid, and that prevents you from taking what would be your natural motion (which would also be free fall).
So, if we free ourselves from defining our motion with respect to the surface of the Earth we realize that the skydiver is not accelerating, while the person who stands on the surface of the Earth is accelerating. Just the opposite of what we usually think. Going back to Galileo's experiment on the leaning tower of Pisa, we can now see why he observed all of his cannonballs to fall at the same rate. It wasn't really the cannonballs that were accelerating away from Galileo at all, it was Galileo that was accelerating away from the cannonballs! ”
-
In GR the surface of the earth is accelerating upwards through spacetime. It is Einstein's way of getting the upwardly accelerating Earth concept to work in RE, since experimental evidence and lack of inertial resistance shows that the Earth is accelerating upwards and that it is not an invisible phenomenon pulling bodies down to the Earth.
I get that in GR, gravity is not a force per se. But it is still a process (for lack of a better term) which causes objects to be attracted to one another. This process is caused by the warping of spacetime.
Gravity as a force and gravity as warping of spacetime may be two different things, but they have the same effect. In order to maintain a flat earth, it seems to me that both would have to be rejected.
And what experimental evidence is there that the earth is accelerating upwards?
-
In GR the surface of the earth is accelerating upwards through spacetime. It is Einstein's way of getting the upwardly accelerating Earth concept to work in RE
In the same paper quoted by fisherman (last paragraph), Einstein says:
The universe then must be closed in itself, and its geometry deviates from that of a spherical or elliptical space only little, and only locally, as, for example, the shape of the earth’s surface deviates from that of an ellipsoid.
You are confusing frames of reference, as used in GR, with reality. Einstein does not have an actual flat Earth actually accelerating upwards; he acknowledges in that quote above that Earth is ellipsoid-like in shape.
You should remember what AATW said in a very recent post, that you step off a chair and see the world accelerate upwards towards you: AATW, who is standing nearby, sees you step off a chair and fall. Both views are valid, but neither in itself proves or disproves a flat, upwards accelerating world. You might as well adopt the view of a skydiver falling headfirst who sees the world accelerating downwards towards her.
-
You are confusing frames of reference, as used in GR, with reality.
He also says in the same paper that the g-field is caused and determined by the energy tensor of matter...he doesn't say that an accelerating earth causes the g-field.
I will add to this with another quote from Einstein. You'll need to read the first part of the paper to get the the context, but the point he makes here is important.
I must warn the reader against a misconception suggested by these considerations. A gravitational field exists for the man in the chest, despite the fact that there was no such field for the co-ordinate system first chosen. We might also think that, regardless of the kind of gravitational field which may be present, we could always choose another reference body such that no gravitational field exists with reference to it. This is by no means true for all gravitational fields, but only for those of a quite special form. It is, for instance, impossible to choose a body of reference such that, as judged from it, the gravitational field of the earth (in its entirety) vanishes.
https://einsteinpapers.press.princeton.edu/vol6-trans/333
The wiki implies that an accelerating earth is the only logical explanation for the equality of gravitational and inertial mass. It is misleading to use so heavily the work and reasoning of Einstein , when he came up with an entirely different explanation.
-
No. There is a reason for why Einstein and physicists have the upwardly accelerating elevator and rocket analogies. It's because experimental evidence shows that gravity behaves as if the Earth were accelerating upwards. These experiments are why Newton's theory of objects falling down through space to the earth was rejected. Gravity operates as if the Earth is accelerating upwards, and this is reflected in the equivalence principle experiments.
https://wiki.tfes.org/Evidence_for_Universal_Acceleration
The Pound–Rebka Experiment
The Pound-Rebka experiment and Pound-Rebka-Snyder experiments are optical tests of the Equivalence Principle, where light redshifts or blueshifts when traveling vertically upwards or downwards. Like with the previous section, light behaves differently when traveling upwards or downwards. In General Relativity (Archive) by Prof. Benjamin Crowell, its author explains that the experiment is a test of the Equivalence Principle:
“ The Pound-Rebka Experiment
The 1959 Pound-Rebka experiment at Harvard was one of the first high-precision, relativistic tests of the equivalence principle to be carried out under controlled conditions ”
From Special and General Relativity (Archive) by Norman K Glendenning on p.28 we read an analogy with an upwardly accelerating spaceship:
“ One can also see the role of the equivalence principle by considering a pulse of light emitted over a distance h along the axis of a spaceship in uniform acceleration g in outer space. The time taken for the light to reach the detector is t = h (we use units G = c = 1). The difference in velocity of the detector acquired during the light travel time is v = gt = gh, the Doppler shift z in the detected light. This experiment, carried out in the gravity-free environment of a spaceship whose rockets produce an acceleration g, must yield the same result for the energy shift of the photon in a uniform gravitational field f according to the equivalence principle. The Pound-Rebka-Snyder experiments can therefore be regarded as an experimental proof of the equivalence principle. ”
The Pound-Rebka-Snyder experiments are the same 1959 experiment, conducted with an additional researcher, which has been improved and repeated over the years to increasing precision (Archive).
Summarily, light will be redshifted or blueshifted when traveling upwards or downwards because "gravity" operates exactly as if the earth were accelerating upwards. When light is traveling downwards from a light source on the ceiling to a detector on the ground, the earth is rising quicker into the photons and will cause a blueshift (its frequency will increase). When light is traveling upwards from the ground to a detector on the ceiling, the detector on the ceiling is moving away from the photons and they will redshift (frequency will decrease).
Experiment Overview Diagram
(https://wiki.tfes.org/images/thumb/5/5c/Pound-rebka-diag.png/375px-Pound-rebka-diag.png)
Left: Light moving downwards - Blueshifted
Right: Light moving upwards - Redshifted
(Source) (Archive)
Redshift and Blueshift of Light
In connection with the above, in the following Redshift-Blueshift Doppler Shift of Light diagram we can see that when a body that emits light is receding from you it would cause a red shift, and when is approaching you quicker it will cause a blue shift:
(https://wiki.tfes.org/images/thumb/d/d3/Doppler_effect.jpg/700px-Doppler_effect.jpg)
(Source) (Archive)
In the Pound–Rebka Experiment when the light suspended on a ceiling travels downwards towards the upwardly moving earth it blueshifts (approaches the detector quicker), and when the light travels away from the earth to the upwardly moving ceiling it redshifts (approaches the detector slower), just as would happen if the building were sitting on an upwardly accelerating earth. Light behaves differently when moving with the motion of the earth than against it.
Sometimes this experiment is called a "proof of General Relativity," but it is a test of the Equivalence Principle which exists within General Relativity. The Equivalence Principle was created years prior to GR. The Equivalence Principle, with the same experimental results, would need to exist in any alternative theory of gravity, such as the theory of the Graviton messenger particles as proposed by Quantum Mechanics. The cornerstone of the Equivalence Principle maintains that gravity and all physical effects operates as if the earth were accelerating upwards.
-
The cornerstone of the Equivalence Principle maintains that gravity and all physical effects operates as if the earth were accelerating upwards.
The operative words here are "as if". "As if", not that the earth is actually accelerating upwards.
In the links I provided, AE himself defined the equivalence principle "as the symmetric "fundamental tensor" determines the metric properties of space, the inertial behavior of bodies in space, as well as the gravitational effects." And he specifically warns against doing exactly what you are doing, taking the analogy literally and trying to make it mean that there is no actual gravitational field.
The EFE can thus also be written as
{\displaystyle R_{\mu \nu }-{\tfrac {1}{2}}Rg_{\mu \nu }+\Lambda g_{\mu \nu }=\kappa T_{\mu \nu }.} {\displaystyle R_{\mu \nu }-{\tfrac {1}{2}}Rg_{\mu \nu }+\Lambda g_{\mu \nu }=\kappa T_{\mu \nu }.}
In standard units, each term on the left has units of 1/length2.
The expression on the left represents the curvature of spacetime as determined by the metric; the expression on the right represents the matter–energy content of spacetime. The EFE can then be interpreted as a set of equations dictating how matter–energy determines the curvature of spacetime.
https://en.wikipedia.org/wiki/Einstein_field_equations
The field equations only include calculation for the curvature of spacetime, not for acceleration of the earth.
-
Gravity operates as if the Earth is accelerating upwards, and this is reflected in the equivalence principle experiments.
Which only holds in the local context. In the local context you can't tell whether a force is pulling you down or something is pushing you up.
Gravitational variations across the globe show that we don't live on an upwardly accelerating plane, and the Einstein quote which has been highlighted to you shows that he was clear about the shape of the earth.
-
You should remember what AATW said in a very recent post, that you step off a chair and see the world accelerate upwards towards you: AATW, who is standing nearby, sees you step off a chair and fall. Both views are valid, but neither in itself proves or disproves a flat, upwards accelerating world.
This is a good point, but I would add that in order for both viewpoints to be valid, there must be a physical cause of the acceleration in both view points. Acceleration requires a force...or a cause if you don't want to define gravity as a force.
The person in the air can assign UA as the reason the ground is rising up. But what cause for accelerating down can the person on the ground assign to the person in the air if there is no gravity? If there is no cause for the person to accelerate down, then both scenarios cannot be equally valid.
This is where the logic that the equivalence principle does away with gravity falls apart. It only works if you assume that a gravitational field exists in the first place.
"Principle of Equivalence. Starting from this limiting case of the special theory of relativity, one can ask oneself whether an observer, uniformly accelerated relative to [inertial coordinate sytem] K in the region considered, must understand his condition as accelerated, or whether there remains a point of view for him, in accord with the (approximately) known laws of nature, by which he can interpret his condition as "rest."...
The answer runs: As far as we really know the laws of nature, nothing stops us from considering the system K' as at rest, if we assume the presence of a gravitational field (homogeneous in the first approximation) relative to K'; for all bodies fall with the same acceleration independent of their physical nature in a homogeneous gravitational field as well as with respect to our system K'.
The assumption that one may treat K' as at rest in all strictness without any laws of nature not being fulfilled with respect to K', I call the "principle of equivalence."
https://einsteinpapers.press.princeton.edu/vol6-trans/249?highlightText=Kottler
-
Although it should be clear from my user tag (or distinct lack thereof), I should preface with saying that my views are my own. I do not speak for "flat earthers", other flat earth researchers, or the flat earth society (including UA). I can only speak for myself.
Spacetime is a joke. It's profoundly stupid. It's supposed to keep an idiot busy and it's been, sadly, effective.
There is no time of any kind. It is not a dimension, it cannot be an independent variable; it is a fictional human concept with no reality. There is no time dilation, travel, or manipulation of any kind. Light's path can only be diverted by direct interaction with matter. Most all of relativity is junk/wrong, but like most all of the incorrect frameworks that came before it - it has limited use.
-
Jack, your unsupported opinions are no more credible than the strange guy on the street on a Saturday afternoon shouting about the Martians planning to kill us all. You need to back up your claims with evidence if they’re to be considered seriously. Other people here, on both sides, produce grounds for their opinions - facts, observations, experimental evidence, and the debate goes on. You just insist something is bunk but don’t back it up, so there’s no debate or conversation to be had.
-
@longitube
Jack, your unsupported opinions are no more credible than the strange guy on the street on a Saturday afternoon shouting about the Martians planning to kill us all.
You are clearly hanging out on some wacky streetcorners! Are you in mesa or phoenix?
I state facts, "matter-of-fact"ly, as most people do. If you want to know more, you should try asking questions!
You need to back up your claims with evidence if they’re to be considered seriously.
What evidence do you require? What evidence do you have now that needs refuting or is contradicted by the facts I listed?
Other people here, on both sides, produce grounds for their opinions - facts, observations, experimental evidence, and the debate goes on.
I don't engage in debate. It is beneath me, and all intellectuals. It's just a silly game / base pageantry for the egotistical sycophants that perform and the entertainment of the audience and judges. It has no place in establishing what is, or isn't. It has no place in science. The fallacies are worth learning, but don't forget about the fallacy fallacy!
You just insist something is bunk but don’t back it up, so there’s no debate or conversation to be had.
That's because you don't ask questions (or disagree, or otherwise "converse" in any way)! I am not here to submit research papers with detailed citation - I'm here for rational discourse! You are always free to ignore me, and learn nothing new!
-
That's because you don't ask questions (or disagree, or otherwise "converse" in any way)!
Yes, we do.
We just don't ask the questions you want to hear, so you either ignore them, or evade them by rambling about why you ignore them.
-
@Tumeni
Do you have an example?
There are many questions I don't have answers to - is that "evading" to you? Or is it because you find my answers unfulfilling / unsatisfying that you think I am doing so intentionally?
-
I state facts, "matter-of-fact"ly...
I don't engage in debate. It is beneath me ...
I'm here for rational discourse! You are always free to ignore me ...
“Facts” likeSpacetime is a joke.
or There is no time of any kind.
These are unsubstantiated opinions, with no reason to believe them given.
However, since debate is beneath you and I’m free to ignore you, forgive me for wasting your valuable time and thank you for the option.
-
@Longitube
These are unsubstantiated opinions, with no reason to believe them given.
They are facts with no evidence to the contrary. Sorry time travel nerds, it's all fantasy!
Thermodynamic process is unidirectional. There is no past, there is no future. There is only now.
However, since debate is beneath you and I’m free to ignore you, forgive me for wasting your valuable time and thank you for the option.
Debate is beneath me, and all smart people - perhaps you as well? I engage for discussion! I am happy for you to supply any evidence for your fiction, at your leisure!
-
All this means that the Earth has infinite space above to move into.
The existance of infinity in one direction shows the existance of infinity in all other directions.
What is in that infinite space?
Other "Earths"?
-
No. There is a reason for why Einstein and physicists have the upwardly accelerating elevator and rocket analogies. It's because experimental evidence shows that gravity behaves as if the Earth were accelerating upwards. These experiments are why Newton's theory of objects falling down through space to the earth was rejected. Gravity operates as if the Earth is accelerating upwards, and this is reflected in the equivalence principle experiments.
As @AllAroundTheWorld mentioned, this only applies at a local level, and the key word is “as if” the Earth is accelerating upwards. It all just depends on the frame of reference. To Isaac Newton sat on the ground, it looked like the apple was falling from the tree towards the Earth. To the apple, it will have felt like the Earth was rising up towards. It doesn’t mean that the Earth is actually accelerating upwards, just feels it is, but its impossible to differentiate without further experimentation. That he did, at a micro and macro scale, and came up with the theories we now call Classical Mechanics.
With his observation, deduction, and verification through experimentation, Newton was able to come up with models for motion and gravitation that accurately predict the motion and position of not only things on Earth like projectiles, but astronomical bodies in orbit around each other. No such testable model or theory exists under FET, just an ascertain that because the observation is like the Earth is constantly accelerating upwards at 9.81 m/s, it must therefore be the case.
As time went on, and understanding increased, the phenomenon we call gravity was explained by curved space, which is a completely equivalent principle. Under this model, gravity is not a force, it’s a geodesic through space, and only felt if one deviates away from that geodesic. The following recent (at the time of writing) is an interesting presentation of the principles:
https://www.youtube.com/watch?v=XRr1kaXKBsU
But, let’s assume that under FET, the Earth is accelerating upwards. Under FET, that also means that everything we see above us is also moving upwards with the same acceleration, including the planets, stars and galaxies, right? If this is the case, why are the effects of gravity different on different sized planets? The planets are used to help slingshot probes into outer reaches of space, and so the acceleration due to gravity is well known. Or are such launches just faked, there are no probes and the photos are all made up? That’s not a condescending question, it’s a probing one (no pun intended).
In your post you also make reference to the effect of redshift and blueshift, which means you must accept the phenomenon, right? Objects moving away from us exhibit redshift and vice versa. Experimental observation of thousands of galaxies shows that they are all exhibiting redshift, indicating they are all moving away from us, and at a rate of around 67 km/s/Mpc. Stars in our local galaxy also exhibit redshift and blueshift.
Assuming FET is true and the stars and galaxies are just points of light in the dome, it would mean that something is slowly changing the colour of those lights. Who or what is controlling the colour of those lights? If they are close in a layer above the Sun and Moon, it all seems like a bit of an extraordinary effort to individually control the colour of thousands/millions of different objects to give the impression that the distance to them is changing.
-
The experiments showing gravitational variations are not controlled - https://wiki.tfes.org/Weight_Variation_by_Latitude
The redshift of galaxies doesn't necessarily mean velocity - https://wiki.tfes.org/Doppler_Shift
-
The experiments showing gravitational variations are not controlled - https://wiki.tfes.org/Weight_Variation_by_Latitude
https://www.jpl.nasa.gov/missions/gravity-recovery-and-climate-experiment-grace/ (https://www.jpl.nasa.gov/missions/gravity-recovery-and-climate-experiment-grace/)
Hardly spring scales and a weight eh? Funny how the evidence put forward literally talks about the use of household equipment and everyday precision scales as used in laboratories, yet chooses to ignore all the other science that is happening. Nevertheless, when conducted with enough precision, and in controlled conditions factoring in air pressure, properly calibrated laboratory scales can be accurate enough. But yeah, as I said, there are far more advanced methods and experimentation techniques out there using highly sophisticated equipment to detect such things. Of course, one could just put forward the claim that NASA are making things up and faking it but this would ideally be backed up by a rational justification and modicum of proof.
We also failed to get an explanation for why the gravity on different planets is different if they are all accelerating at the same rate. Remember, the gravity of the planets has been calculated, tested, and proven by the use of said planets in calculating slingshot trajectories.
The redshift of galaxies doesn't necessarily mean velocity - https://wiki.tfes.org/Doppler_Shift
The Wiki article, like a lot that I've read on here, is full of references and carefully selected snippets where the general direction is one of dismissing that which favours RET and accepted, tested, scientific theory. The fact of the matter is, all of the galaxies are redshifted, and so are some stars in our own galaxy. Some of the stars are blueshifted. Here's a more accurate and fair reflection of what redshift is and means:
https://en.wikipedia.org/wiki/Redshift (https://en.wikipedia.org/wiki/Redshift)
Redshift occurs because of three main reasons:
1. Astronomical bodies are moving away from each other (doppler effect)
2. Space itself is expanding, causing light to be redshifted (cosmological redshift)
3. Distortion due to strong gravitational fields (gravitational redshift)
Regardless of reason, redshift is measured. So, how does FET account for it in the galaxies and stars that said to be small points of light in a celestial dome just a few thousand miles above the surface of the Earth? What, or who accounts for, and changes the colour of literally thousands/millions of small spots of light, just to make it look like they are redshifted or blueshifted relative to Earth? What purpose would that serve in a flat Earth model?
-
The experiments showing gravitational variations are not controlled - https://wiki.tfes.org/Weight_Variation_by_Latitude
Apparently the NIST experiment referencing gravitational time dilation was sufficiently controlled for you. It demonstrates gravitational variations.
No. There is a reason for why Einstein and physicists have the upwardly accelerating elevator and rocket analogies. It's because experimental evidence shows that gravity behaves as if the Earth were accelerating upwards. These experiments are why Newton's theory of objects falling down through space to the earth was rejected. Gravity operates as if the Earth is accelerating upwards, and this is reflected in the equivalence principle experiments
.
As has been pointed out to you numerous times, and you keep ignoring...this only applies locally. More importantly, it only applies to objects that are in free fall. Gravity effects countless things that have nothing to do with free fall...from circulatory systems, the way plants grow to roller coasters.
-
What, or who accounts for, and changes the colour of literally thousands/millions of small spots of light, just to make it look like they are redshifted or blueshifted relative to Earth? What purpose would that serve in a flat Earth model?
Whoah, tiger. Redshift doesn’t change the colour of the stars as we see them: Betelgeuse isn’t reddish because of redshift, nor is Sirius blueish because of blueshift. You’re not alone, I’ve seen others here make the same mistake, but redshift or blueshift in astronomy is the absorption spectra of eg helium within starlight shifting from their regular positions towards the red or blue end of visible light due to Doppler effect. That Wikipedia article you linked explains it.
-
Whoah, tiger. Redshift doesn’t change the colour of the stars as we see them: Betelgeuse isn’t reddish because of redshift, nor is Sirius blueish because of blueshift. You’re not alone, I’ve seen others here make the same mistake, but redshift or blueshift in astronomy is the absorption spectra of eg helium within starlight shifting from their regular positions towards the red or blue end of visible light due to Doppler effect. That Wikipedia article you linked explains it.
OK, I like your style, and yes, you’re right it’s not a humanly detectable change in colour per se, it’s a shift towards the red or blue end of the spectrum relative to where it would be expected if it were not moving with respect to us.
https://lco.global/spacebook/light/redshift/ (https://lco.global/spacebook/light/redshift/)
What I’m not clear on is how FET accounts for this observation. All I seem to find are articles that claim redshift is caused by other things, not just relative motion/velocity, so astronomical doppler effect is ruled out. We know that expanding space would cause the same effect, and we know that strong gravitational fields can also cause the effect. So which is it?