Post by: ExplorerJade on May 27, 2020, 04:54:19 PM
According to the FE theory, the Earth moves upwards due to a constant acceleration caused by dark energy/the Davis plane.
Since as it is mentioned in the Wiki that the Davis Plane theory is still in progress, I'm going to assume that the dark energy is the explanation most Flat Earthers agree on.
Dark energy was discovered by two international teams that included astronomers.
But, according to the sub-topic on this website- The Cosmos- it states that astronomy is 'pseudoscience', the reason being that astronomers cannot experiment to prove their hypotheses.
And also, on the same page and I'm pretty sure on every other page on this website, it states that experimentation is required to prove a hypothesis (which I agree with).
"Without experimentation, the steps of the Scientific Method are unable to be fulfilled. The researcher of the science is left in the dark to build one hypothesis upon the next: A 'house of cards' model of nature without solid empirical foundations. - https://wiki.tfes.org/Astronomy_is_a_Pseudoscience
Do you see where I'm getting with this?
So, doesn't it seem almost hypocritical when you create a theory (in this case, the dark energy theory) based off of hypotheses made by astronomers?
If there are other theories on universal acceleration, please let me know.
I'm merely trying to understand how the Flat Earth Theory works and I'm simply confused due to all this contradicting points.
Post by: Pete Svarrior on May 27, 2020, 05:44:15 PM
Dark energy was discovered by two international teams that included astronomers.The FE term "Dark Energy" is not to be confused with dark energy as defined within astronomy. While both refer to a largely unknown force, they are not one and the same.
Do you see where I'm getting with this?No. If you want to make a point, make it. We won't be trying to guess.
Post by: Regicide on May 27, 2020, 09:04:06 PM
Post by: Clyde Frog on May 27, 2020, 09:18:04 PM
Post by: Regicide on May 27, 2020, 10:18:28 PM
It’s only a problem if you are mistakenly under the impression that something is somehow prohibited from undergoing constant acceleration for an arbitrary length of time. Which would put you at odds with long established theory from some great scientific minds, but you’d be far from the first person to plant a flag on that hill just to die on it.I'm unsure as to why you think that I am mistaken. You have made a statement but failed to provide any evidence. What theory, what scientists? I'm honestly unsure as to whether this is authentic or a joke. The speed of light in a certain medium is a speed barrier that cannot be surpassed, numerous experiments have proved this. One such example is the phenomenon of Cherenkov radiation, which is the blue glow observed in nuclear coolant pools. Light travels much slower underwater than in a vacuum, so nuclear material can emit radiation that would be traveling faster than light in water. This cannot happen, and so the particles emit photons to release energy.
If you are referring to linear acceleration, then I am right. An object is prohibited from undergoing linear acceleration for an arbitrary length of time. Acceleration is change of velocity. For a linearly accelerated flat earth to match empirical observations of gravity, the world would have to constantly increase it's velocity. At some point, in this case just under a year as I previously mentioned, the world would reach the speed of light. The idea of the speed of light then has to either be dispelled with, which contrasts with observations, or has to be somehow overcome. The acceleration cannot be changed, because that would result in a perceived change of gravity. The speed of the earth cannot be changed, because then everyone would smack into the ceiling at the speed of light (which would be quite a sight).
If you are talking about centrifugal acceleration, on the other hand, there is quite another problem. Centrifugal acceleration is observably different from gravity. Just watch this amazing video by Tom Scott:
https://www.youtube.com/watch?v=bJ_seXo-Enc
Flat Earthers and Round Earthers generally agree that linear acceleration and gravity are indistinguishable. That's the only reason the idea of a universal accelerator works.
However, since a centrifugal accelerator is distinguishable from gravity, a centrifugal accelerator cannot be used. No matter how much the inconstancies are removed by scaling up the contraption, they will still be there.
Post by: iamcpc on May 27, 2020, 10:23:14 PM
Okay, here's the thing.
According to the FE theory, the Earth moves upwards due to a constant acceleration caused by dark energy/the Davis plane.
I first had an issue with UA because I'm able to sense acceleration and I don't sense the ground i'm standing on accelerating up.
Pete had offered a pretty sound explanation that, being born into this acceleration, you would not be able to sense it the same way you can sense other acceleration which, to me, made perfect sense. Sound logical explanation.
Another thing is that i'm not able to sense the acceleration of other things. Just myself. If a ball suddenly started accelerating toward me and I was not looking I could not sense that. If I was blindfolded in a car I could still sense the acceleration of the car.
Then I fell down today. When I fell I DEFINITELY sensed acceleration which I had previously discussed. This, to me at least, shows that I am the one accelerating down because i'm unable to sense the acceleration of objects outside of my body.
The same thing happened when I jumped off the diving board. I didn't sense that I was floating weightless. I sensed that I was accelerating down toward the water. I wonder how this observation is possible in the UA model.
Post by: Clyde Frog on May 27, 2020, 10:33:33 PM
I'm quite certain you can't demonstrate that you are right, because doing so would violate General Relativity, which I strongly suspect is the very theoretical framework you are referring to when you say nothing can travel faster than "the speed of light" (which you probably meant to call simply c, or the vacuum speed of light, but whatever it doesn't matter). The issue is that you are defining the speed of something either against some sort of a preferred FoR (which doesn't exist) or from some independent observer's FoR, which is necessarily going to be different than that of an observer standing on the surface of a constantly accelerating disc.It’s only a problem if you are mistakenly under the impression that something is somehow prohibited from undergoing constant acceleration for an arbitrary length of time. Which would put you at odds with long established theory from some great scientific minds, but you’d be far from the first person to plant a flag on that hill just to die on it.I'm unsure as to why you think that I am mistaken. You have made a statement but failed to provide any evidence. What theory, what scientists? I'm honestly unsure as to whether this is authentic or a joke. The speed of light in a certain medium is a speed barrier that cannot be surpassed, numerous experiments have proved this. One such example is the phenomenon of Cherenkov radiation, which is the blue glow observed in nuclear coolant pools. Light travels much slower underwater than in a vacuum, so nuclear material can emit radiation that would be traveling faster than light in water. This cannot happen, and so the particles emit photons to release energy.
If you are referring to linear acceleration, then I am right. An object is prohibited from undergoing linear acceleration for an arbitrary length of time. Acceleration is change of velocity. For a linearly accelerated flat earth to match empirical observations of gravity, the world would have to constantly increase it's velocity. At some point, in this case just under a year as I previously mentioned, the world would reach the speed of light. The idea of the speed of light then has to either be dispelled with, which contrasts with observations, or has to be somehow overcome. The acceleration cannot be changed, because that would result in a perceived change of gravity. The speed of the earth cannot be changed, because then everyone would smack into the ceiling at the speed of light (which would be quite a sight).
So. The ball is in your court. If you'd like to disprove Relativity, have at it, but you own the burden of proof if that's the path you want to go down. I'll pick Einstein in this particular battle of wits though. At least he knew his own model.
Post by: Regicide on May 27, 2020, 10:42:06 PM
Post by: Pete Svarrior on May 27, 2020, 10:51:42 PM
Then I fell down today. When I fell I DEFINITELY sensed acceleration which I had previously discussed. This, to me at least, shows that I am the one accelerating down because i'm unable to sense the acceleration of objects outside of my body.It sounds to me like you misunderstood what I said previously. You can certainly feel your own weight. Lie down on your back and you can feel your back pressing against the floor (and vice versa). Sit in an accelerating car* and you can feel the car seat press against your back. That's all that "feeling acceleration" is in everyday scenarios.
The same thing happened when I jumped off the diving board. I didn't sense that I was floating weightless. I sensed that I was accelerating down toward the water. I wonder how this observation is possible in the UA model.
What you felt when you fell was a brief experience of weightlessness/free-fall. This, too, can be colloquially described as "feeling acceleration", but it's a wholly distinct phenomenon. It sounds to me that by using an ambiguous term, you accidentally drew an equivalence between the two.
In the free-fall scenario, it follows from Einstein's Equivalence Principle that you cannot tell the difference between yourself falling down and yourself being perfectly still in an ever-accelerating body of air. To disagree with this principle is not to highlight an "issue" with UA - it's just a case of dismissing modern physics based on nothing other than a flawed intuition. You cannot claim to support RET while discarding some of its core aspects.
* - technically, the car would have to be accelerating at a perfect constant rate for this analogy to work, which might not be very easy to ensure in practice
As for Regicide: your question is already answered in the article on Universal Acceleration. In short, your impression of how acceleration works is rooted in classical mechanics, which doesn't provide reliable results at relativistic velocities. You need to read up on Special Relativity to be able to argue this reliably.
Post by: existoid on May 27, 2020, 11:41:32 PM
you cannot tell the difference between yourself falling down and yourself being perfectly still in an ever-accelerating body of air.
I'm not so sure.
Thought experiment -
Imagine you are blindfolded and placed on a chair on a platform near the top of a tall, empty silo. The chair is attached to silent bungee cords.
There are also fans below.
You are told that EITHER the platform will be silently and swiftly removed, and you'll fall OR the fans will blow air that is accelerating at exactly 9.8 m/s squared (or whatever it is).
The bungee cords have been engineered to slow your descent and stop at a specified gently rate, and the fans would slow the airflow at the same rate.
Do you believe you would definitely not be able to tell whether you were actually falling, or whether there was simply a body of air accelerating around you?
(I've probably gone a little overboard and could have made this thought experiment a little simpler).
Is this yet another body of science that FET will have to contend with? (not referring to a "science of falling" ;D but biology and our understanding of the inner ear that tells us about balance, motion, acceleration of our body).
https://en.wikipedia.org/wiki/Falling_(sensation)
Post by: Pete Svarrior on May 28, 2020, 12:33:39 AM
Unfortunately, it is you who will have to "contend" with physics to make your claim work. Namely, the Equivalence Principle. If you find a way to disprove this principle, you will have completely destroyed the foundations of the Round Earth Theory. Aside from being an own goal, I somehow doubt your chances of success.
Your anecdote on the inner ear makes things even more complicated. You're no longer just discussing free-fall (which was already too complex for you to appropriately work with), but you are now introducing additional momenta and rotation. If you want to rely on that particular sensation, you'll have to adjust your experiment to include those factors. Notably, this is another case of abusing ambiguous terms - falling over is not free-fall, but you chose to refer to both as "falling".
This discussion will be useless unless you choose a scenario and describe it accurately. Mixing them up, or picking and choosing from completely different scenarios, is not going to help you understand the physics here.
Note that none of this touches on FET, not yet. We're just discussing high school physics.
Post by: Regicide on May 28, 2020, 01:35:32 AM
However, Pete, Equivalence Principle is not a foundation of Round Earth Theory, unless I'm somehow mistaken. I agree that, since none of us are Einsteins, it will be nigh impossible to disprove Equivalence Theory. However, Equivalence Theory is unrelated to either school of thought.
Any further discussion of Equivalence theory would not only be beating a dead horse, but also beating a horse that belongs to neither of the beaters and is actually a donkey.
Post by: Pete Svarrior on May 28, 2020, 01:53:33 AM
However, Equivalence Theory is unrelated to either school of thought.This is untrue. The consequences of the physics behind EP are essential for either model to work. If you prove that it doesn't actually work, you've disproved RET.
Sadly, the horse is far from dead. So far, we have two people here who claim that EP doesn't work, and then we have you who thinks Lorentz transformations don't apply. We can't have people claiming to defend RET while just throwing physics out the window.
Post by: Stagiri on May 28, 2020, 06:33:49 AM
It’s only a problem if you are mistakenly under the impression that something is somehow prohibited from undergoing constant acceleration for an arbitrary length of time. Which would put you at odds with long established theory from some great scientific minds, but you’d be far from the first person to plant a flag on that hill just to die on it.I'm unsure as to why you think that I am mistaken. You have made a statement but failed to provide any evidence. What theory, what scientists? I'm honestly unsure as to whether this is authentic or a joke. The speed of light in a certain medium is a speed barrier that cannot be surpassed, numerous experiments have proved this. One such example is the phenomenon of Cherenkov radiation, which is the blue glow observed in nuclear coolant pools. Light travels much slower underwater than in a vacuum, so nuclear material can emit radiation that would be traveling faster than light in water. This cannot happen, and so the particles emit photons to release energy.
If you are referring to linear acceleration, then I am right. An object is prohibited from undergoing linear acceleration for an arbitrary length of time. Acceleration is change of velocity. For a linearly accelerated flat earth to match empirical observations of gravity, the world would have to constantly increase it's velocity. At some point, in this case just under a year as I previously mentioned, the world would reach the speed of light. The idea of the speed of light then has to either be dispelled with, which contrasts with observations, or has to be somehow overcome. The acceleration cannot be changed, because that would result in a perceived change of gravity. The speed of the earth cannot be changed, because then everyone would smack into the ceiling at the speed of light (which would be quite a sight).
(...)
Actually, as TheRealDave has mentioned, that wouldn't be a problem, at least according to Einstein's theory of relativity. It just depends on how you look at it.
Let's suppose there's an outer space where one's somehow free from the influence of the UA. In that outer space, an observer is watching the FE being accelerated by the UA. Let's call him Adam. Let's also say that Adam has a really god eyesight and so is able to oversee the entire trajectory of the FE.
From Adam's perspective, the FE is accelerating and thus gaining speed. As you've correctly said, no object with mass - and the FE definitely has mass - can achieve the speed of light. So, as the speed of the FE in relation to Adam's FoR gets closer and closer to the speed of light, the acceleration starts to noticeably decrease. The FE could accelerate for eternity but since the acceleration diminishes it would never reach the speed of light, just get closer and closer to it.
However, that's just what would seem to be going on from Adam's perspective. For an observer living on the FE, let's call her Eve, things would be different. She lives on the FE and she is accelerated along with it. Her FoR is non-inertial so she experiences the inertial force of gravitation. However, in her FoR, the FE is in relative rest, there's no speeding up and so there's no getting close to the speed of light. So from Eve's perspective, this could go on for ever even as the inertial force of gravitation stays constant.
Post by: Stagiri on May 28, 2020, 09:24:04 AM
(...)
If you are talking about centrifugal acceleration, on the other hand, there is quite another problem. Centrifugal acceleration is observably different from gravity. Just watch this amazing video by Tom Scott:
https://www.youtube.com/watch?v=bJ_seXo-Enc
(...)
That difference would diminish if you increased the radius of rotation. For a radius large enough, it could be too small to observe. Also, in the video it's said that you would gradually adapt.
Post by: Clyde Frog on May 28, 2020, 12:11:21 PM
Before I go on, Dave, I am unsure as to what you are arguing. Your arguments seem to support a round earth, which is what I support. Are we beating a dead horse, because I am an RE supporter. We seem to be arguing the same point.No, you were arguing that an object cannot undergo constant acceleration indefinitely because it would eventually exceed c, therefore the Universal Acceleration model for FE is impossible.
You began with a false premise, your argument is unsupported. I'm basing my response on the same set of principles you invoked when you brought up the universal speed limit.
Post by: Regicide on May 28, 2020, 07:08:30 PM
Post by: Groit on May 28, 2020, 08:43:25 PM
All we need now is a rocket ;D
Post by: Pete Svarrior on May 28, 2020, 09:24:09 PM
There's only one way to test this, and that is to build a rocket, accelerate it upwards at around 3g until it reaches a velocity of a little over 11 km s-1 relative to the surface of the Earth. If the rocket escapes the Earth carries on into space with the same relative velocity then RE gravity is correct. If however, the Earth slams into the back of the rocket after some period of time since the Earth is accelerating, then FE Universal Acceleration is correct.This, once again, defies the equivalence principle or the definition of gravity under the FE model - it's hard to say which one because you provided very little information on your actual reasoning. Whenever you say that you've found a way to distinguish things that are indistinguishable by definition, you probably did a dumb.
In short: no, FET does not go against the idea of escape velocities.
Post by: Groit on May 28, 2020, 09:38:04 PM
In short: no, FET does not go against the idea of escape velocities.
Is there anything in the wiki on this?
Post by: Pete Svarrior on May 28, 2020, 09:52:01 PM
Is there anything in the wiki on this?Yes, it's described in the "The Basics" paragraph of the UA page (https://wiki.tfes.org/Universal_Acceleration#The_Basics). Universal Acceleration is, well, universal. The main (but likely not only) reason for objects immediately above the Earth not being affected by it is that the Earth's mass shields us from the effect. Once you're sufficiently far away, you will have escaped the Earth's "gravitational" effect, or the nullification thereof.
For other factors, you could consult the Variations in Gravity (https://wiki.tfes.org/Variations_in_Gravity) page.
Post by: Groit on May 28, 2020, 10:21:29 PM
Yes, it's described in the "The Basics" paragraph of the UA page (https://wiki.tfes.org/Universal_Acceleration#The_Basics). Universal Acceleration is, well, universal. The main (but likely not only) reason for objects immediately above the Earth not being affected by it is that the Earth's mass shields us from the effect. Once you're sufficiently far away, you will have escaped the Earth's "gravitational" effect, or the nullification thereof.
So would i be right in saying that when you reach a certain height above the Earth's surface, then you will start to feel the effects of universal acceleration?
Post by: Stagiri on May 29, 2020, 07:49:04 AM
Post by: ExplorerJade on May 29, 2020, 11:29:17 AM
The FE term "Dark Energy" is not to be confused with dark energy as defined within astronomy. While both refer to a largely unknown force, they are not one and the same.
Then can you explain to me, with proof, as to what is 'dark energy' in the FE theory?
Post by: Pete Svarrior on May 29, 2020, 02:09:51 PM
So would i be right in saying that when you reach a certain height above the Earth's surface, then you will start to feel the effects of universal acceleration?Yes, you would be right in repeating what I just said. But before you jump to your next "gotcha!", you might want to familiarise yourself with the resources I linked you to.
Then can you explain to me, with proof, as to what is 'dark energy' in the FE theory?No, I cannot explain to you what an unknown force is. If I could, it wouldn't be described as unknown.
Post by: iamcpc on May 29, 2020, 03:24:22 PM
It sounds to me like you misunderstood what I said previously. You can certainly feel your own weight. Lie down on your back and you can feel your back pressing against the floor (and vice versa). Sit in an accelerating car* and you can feel the car seat press against your back. That's all that "feeling acceleration" is in everyday scenarios.
What you felt when you fell was a brief experience of weightlessness/free-fall. This, too, can be colloquially described as "feeling acceleration", but it's a wholly distinct phenomenon. It sounds to me that by using an ambiguous term, you accidentally drew an equivalence between the two.
In the free-fall scenario, it follows from Einstein's Equivalence Principle that you cannot tell the difference between yourself falling down and yourself being perfectly still in an ever-accelerating body of air.
I did some research and found this video which explains this in great detail. Would there be any benefit to having this video on the wiki? It clearly demonstrates how it would be impossible to tell the difference between acceleration and a gravitational field.
https://www.youtube.com/watch?v=mAtRD9_4Oa0
Post by: ExplorerJade on May 29, 2020, 03:38:39 PM
So would i be right in saying that when you reach a certain height above the Earth's surface, then you will start to feel the effects of universal acceleration?Yes, you would be right in repeating what I just said. But before you jump to your next "gotcha!", you might want to familiarise yourself with the resources I linked you to.Then can you explain to me, with proof, as to what is 'dark energy' in the FE theory?No, I cannot explain to you what an unknown force is. If I could, it wouldn't be described as unknown.
Okay, then can you submit proof that the said force exists?
Post by: Clyde Frog on May 29, 2020, 04:43:36 PM
On a disc-shaped FE, the proof would be that things fall down. A force that makes things fall down on Earth exists. The shape of the Earth will put some parameters around what that force might be and how it might work.So would i be right in saying that when you reach a certain height above the Earth's surface, then you will start to feel the effects of universal acceleration?Yes, you would be right in repeating what I just said. But before you jump to your next "gotcha!", you might want to familiarise yourself with the resources I linked you to.Then can you explain to me, with proof, as to what is 'dark energy' in the FE theory?No, I cannot explain to you what an unknown force is. If I could, it wouldn't be described as unknown.
Okay, then can you submit proof that the said force exists?
Post by: iamcpc on May 29, 2020, 07:41:44 PM
This analogy is not appropriate. In order to correctly simulate this, you'd have to find a way to switch gravity/UA off and on on demand. Bungee cords, platforms, or any other form of suspension won't do it.
Unfortunately, it is you who will have to "contend" with physics to make your claim work. Namely, the Equivalence Principle. If you find a way to disprove this principle, you will have completely destroyed the foundations of the Round Earth Theory. Aside from being an own goal, I somehow doubt your chances of success.
Your anecdote on the inner ear makes things even more complicated. You're no longer just discussing free-fall (which was already too complex for you to appropriately work with), but you are now introducing additional momenta and rotation. If you want to rely on that particular sensation, you'll have to adjust your experiment to include those factors. Notably, this is another case of abusing ambiguous terms - falling over is not free-fall, but you chose to refer to both as "falling".
This discussion will be useless unless you choose a scenario and describe it accurately. Mixing them up, or picking and choosing from completely different scenarios, is not going to help you understand the physics here.
Note that none of this touches on FET, not yet. We're just discussing high school physics.
I agree. After researching this the below video really clarified this for me.
https://www.youtube.com/watch?v=mAtRD9_4Oa0
After researching the Equivalence principle this makes a lot more sense. Thank you so much Pete! I understand now that a humans sense of acceleration vs our feeling of a gravitational field could not tell the difference. I love how people are able to make these things more clear.
Would it be a good idea to put this video on the wiki?
Post by: Tom Bishop on May 30, 2020, 02:22:55 PM
It also explains why multiple objects of different masses fall without exhibiting the inertial resistance which normally occurs when bodies are pulled or pushed through space. It takes more force to roll a bowling ball across the floor than a marble. So it is curious how 'gravity' knows how to equalize the inertial resistance all bodies naturally exhibit when they are pulled or pushed through space so they fall at the same rate.
Post by: Stagiri on May 30, 2020, 02:55:06 PM
(...) It takes more force to roll a bowling ball across the floor than a marble. So it is curious how 'gravity' knows how to equalize the inertial resistance all bodies naturally exhibit when they are pulled or pushed through space so they fall at the same rate.
It's not curious at all, it's interesting at most. Yes, it takes more force to accelerate a heavier object. On the other hand, since it's heavier, the gravitational force is also greater.
If
F = the force affecting an object
m = the mass of the object
a = the acceleration of the object
M = the mass of the Earth
then according to the Newton's law:
(https://i.imgur.com/07g9Oi2.png)
So, the difference cancels out, i. e. the acceleration of an object in a gravity field does not depend on the mass of said object, just on the mass of what's attracting it.
Post by: Tom Bishop on May 30, 2020, 04:33:23 PM
What about on another planet like the conventional Saturn where, assuming that it had a surface that you could stand on, g is stronger? The inertial resistance of a body stays the same throughout the universe (on Earth, in weightless space, on Saturn), but g can change.
Why should the Earth be so special that gravity exactly cancels out with inertial resistance on Earth to a very high precision but not on any other planet or environment?
Post by: Stagiri on May 30, 2020, 08:20:19 PM
Really? Gravity cancels out exactly with inertial resistance by pulling harder for heavier objects?
(...)
Yes, exactly. Inertial mass and gravitational mass are the same thing, mass, so of course that while the inertia is bigger so is the intensity of the force.
(...)
What about on another planet like the conventional Saturn where, assuming that it had a surface that you could stand on, g is stronger? The inertial resistance of a body stays the same throughout the universe (on Earth, in weightless space, on Saturn), but g can change.
(...)
The g is the same thing as the a from the equations above, i. e. the gravitational acceleration of objects. As you can see from said equations, it is proportional to the mass M of the planet and not dependant on the mass of an object. Having greater mass M, Saturn attracts any object much more than Earth does, hence the greater g / a.
Why should the Earth be so special that gravity exactly cancels out with inertial resistance on Earth to a very high precision but not on any other planet or environment?
It isn't special. The mass of an object is the mass of an object, it does not depend on what planet you are closer to. It cancels out with itself the same way 2/2, 3/3, n/n cancels out to 1. You can see that from the equations above (or you can, you know, google it as you are supposed to).
Post by: Tom Bishop on May 30, 2020, 09:12:48 PM
Can you clarify this? Why is the inertial force of a bullet or bowling ball approaching you the same in weightless space and on Earth? According to that logic inertial resistance should disappear in a weightless environment far from gravitational fields.
If a bowling ball is in vertical free fall towards the surface of Saturn, are you claiming that it would take more force to move it sideways horizontally during its downwards descent than on Earth, since the bowling ball now has a greater inertial mass? And if not, why should the force to move that object sideways horizontally be the same as on Earth or in weightless space?
Post by: Stagiri on May 31, 2020, 12:57:31 PM
Sorry, can you clarify? You appear to be claiming that a body's inertial mass and inertial resistance changes when under different levels of gravity.
Can you clarify this? Why is the inertial force of a bullet or bowling ball approaching you the same in weightless space and on Earth? According to that logic inertial resistance should disappear in a weightless environment far from gravitational fields.
If a bowling ball is in vertical free fall towards the surface of Saturn, are you claiming that it would take more force to move it sideways horizontally during its downwards descent than on Earth, since the bowling ball now has a greater inertial mass? And if not, why should the force to move that object sideways horizontally be the same as on Earth or in weightless space?
Sorry, perhaps I've expressed it poorly but I am not claiming that a body's mass changes. It stays the same.
F = m*a. F is the force applied to a body, m its mass and a its acceleration. From that, you can see that a = F/m, that is that the acceleration of a body is proportional to the force applied to it divided by its mass.
Suppose we have an object A and a two times heavier object B. The same force will accelerate B less (by a half) because it has two times greater mass. Alternatively, a two times greater force has to be applied to B if you want both objects to accelerate the same way. So far so good?
Now, let's take the Newton's law of gravity F_g = k*m*M/r^2. F_g is the gravitational force, k is a constant, m and M are masses of two bodies and r is the distance between them. If the distance increases the gravitational force decreases. If one (or both) of the masses increases the gravitational force increases too.
Let's return to objects A and B and let's drop them on the Earth's surface. Object A has a mass m and is accelerated towards the Earth by gravitational force F, so it achieves acceleration a. Object B has a mass 2m so it's two times harder to accelerate. At the same time, object B has mass 2m so the gravitational force between object B and the Earth is 2F. It's two times harder to accelerate object B but the force accelerating it towards the Earth is two times greater as well. So, 2F/2m = F/m = the same acceleration a towards the Earth. In conclusion, A and B are accelerated identically towards the Earth.
Now, let's take objects A and B to Saturn and drop them there. Object A has the same mass m but Saturn's mass is much greater than Earth's mass. So, the gravitational force is greater, not because object A's mass m would be different but because the planet's mass M is greater. So on Saturn, object A achieves much larger gravitational acceleration a (or g) than on Earth. Nevertheless, the same that applied to the relation between objects A and B on Earth applies on Saturn. Object B still has the same mass 2m so it's still two times harder to accelerate. At the same time, object B still has the same mass 2m so the gravitational force between object B and Satrun is again twice greater. It's two times harder to accelerate object B but the force accelerating it towards Saturn's core is two times greater as well. In conclusion, A and B are accelerated identically even when on Saturn.
The same goes for any planet/star/whatever. Bodies with different mass are harder (or easier) to accelerate but at the same time the gravitational force between a body and the planet/star/... is greater(/smaller). So in conclusion, all the bodies on the same planet/star/... are acceleratde the same way, none, every has the same acceleration g. However, the particular value of acceleration depends on the mass of the planet/star/... so different planets/stars/... have different gs, different values of acceleration of bodies on their surface.
Is it clearer now?
Post by: Groit on June 07, 2020, 01:00:17 PM
However, Equivalence Theory is unrelated to either school of thought.This is untrue. The consequences of the physics behind EP are essential for either model to work. If you prove that it doesn't actually work, you've disproved RET.
Why would it disprove RET?
If there are any subtle flaws within the Equivalence Principle then we could use this to determine whether we are accelerating due to gravity or UA. It would actually prove on or the other.
Post by: Bikini Polaris on June 07, 2020, 03:55:19 PM
I also have some doubts over the Universal accelerator. If the earth were really accelerating constantly at approximately 9.8 meters per second^2, then from a halt it would reach the speed of light in just under a year. Does this mean that FET denies the speed of light as a universal speed limit? I know that there is some disagreement in the community over this, but this is a problem that has to be avoided somehow.
As far as I understand no, the speed of light is a limit only in relativistic terms, but from your own perspective it's not. I.e., on your own spaceship with infinite energy you can accelerate to a speed much faster than light and reach a destination whose distance has been covered faster than light. *But* for someone watching you from Earth, you aren't going faster than light. The trick here is that you will age at a slower rate than those people on Earth, so from their perspective it indeed took you the "right slower than speed of light" time to reach your destination. See here: https://www.quora.com/Is-it-possible-to-accelerate-at-a-constant-rate-until-reaching-the-speed-of-light
Once you're sufficiently far away, you will have escaped the Earth's "gravitational" effect, or the nullification thereof.
That's at odds with the fact that the flat surface we would be on is now travelling upwards at quite a fast speed (incredibly greater than the speed of light).
Post by: Pete Svarrior on June 07, 2020, 06:41:02 PM
Why would it disprove RET?Well, if you declare a central tenet of your model to be false, that necessarily requires you to decline the model in its current form. It's really not much more profound than that - if you conclude that RET is false, then you conclude that RET is false.
If there are any subtle flaws within the Equivalence PrincipleWe are not discussing "subtle flaws" here. The contention is whether or not the Equivalence Principle should be discarded. I propose that it shouldn't.
That's at odds with the fact that the flat surface we would be on is now travelling upwards at quite a fast speed (incredibly greater than the speed of light).Please complete your assertion by answering the following question: Relative to what frame of reference?
Once your assertion has been made complete and coherent, please explain: How have you concluded this?
Post by: Regicide on June 09, 2020, 03:49:53 PM
However.
I find it odd that FET states that the effects of the universal accelerator begin to take effect as one gets further away from Earth. It's almost as if as someone moved further away from the earth they would begin to experience some sort of difference in their attraction to Earth. Almost some sort of weightlessness...
Post by: Groit on June 09, 2020, 10:31:52 PM
(https://i.imgur.com/iWp7LsF.png)
So, according to the diagram light moving downwards will be blueshifted.
In FET all celestial bodies are accelerating at the same rate, but at the same time the stars and all those smudges of light that we call galaxies also rotate around the Earth. So if we were to observe the stars (and those smudges of light) when they are directly above us, according to EP, they should all be blueshifted, because the time from light emitted to it reaching our eyes the Earth has accelerated and thus the light will be blueshifted.
So how come we don't observe this?! in fact most of those smudges of light that we call galaxies are actually redshifted!
How does FET explain this? please don't tell me its to do with bendy light ;)
Post by: Tom Bishop on June 09, 2020, 10:57:56 PM
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So how come we don't observe this?! in fact most of those smudges of light that we call galaxies are actually redshifted!
Redshifted compared to what? The Sun?
Post by: IronHorse on June 09, 2020, 11:06:44 PM
It's just doppler effect except at the wavelengths of light rather than sound.
Post by: Pete Svarrior on June 10, 2020, 10:42:55 AM
I'll say it again slowly. Equivalence Theory is not a central part of either model.It doesn't matter how slowly you type, you continue to be wrong. If you disprove EP, then you disprove the physics that directly concludes EP. In doing so, you disprove RET in its current form.
My proposal is that you won't be able to accomplish this, but also that you probably don't want to.
I find it odd that FET states that the effects of the universal accelerator begin to take effect as one gets further away from Earth.You are expected to develop an understanding of the basics before posting here. Please do so before continuing with the debate.
In FET all celestial bodies are accelerating at the same rateThis statement is false. Your issue stems from making poor assumptions.
All celestial bodies (that we know) share UA, but UA is not the only contributing factor to their motion. If it was, we'd perceive all celestial bodies as stationary relative to one another. Surely you knew this is not the case, so why waste our time with something so poorly thought out?
Post by: AATW on June 10, 2020, 12:04:02 PM
Right, but you're using RET here to mean "the whole of physics". And yeah, it would fundamentally change our understanding of things. But I think Regicide is talking about RET in the more literal sense of the theory that the earth is round [shouldn't it really be GET, btw?]I'll say it again slowly. Equivalence Theory is not a central part of either model.It doesn't matter how slowly you type, you continue to be wrong. If you disprove EP, then you disprove the physics that directly concludes EP. In doing so, you disprove RET in its current form.
The shape of the earth (either way) isn't contingent on Equivalence Theory being true.
Post by: IronHorse on June 10, 2020, 12:06:33 PM
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All celestial bodies (that we know) share UA, but UA is not the only contributing factor to their motion.
So what are these other contributing factors to their motion?
Post by: Pete Svarrior on June 10, 2020, 02:33:06 PM
Right, but you're using RET here to mean "the whole of physics".More or less, yes. Does that affect the validity of my argument, in your mind?
If xXx_SuperScienceMan69_xXx comes to the Flat Earth Society to explain how big-brained he is and how he totally pwned FET with FACTS and LOGIC, should he be allowed to just conclude that "basic physics is false, ergo FET debunked"? In my view, the answer is "no", because in doing so he'd be debunking RET as well. This is necessarily the case, because RET (regardless of whether you go for the more broad meaning of the term or a very minimalistic and literal one) is strictly a subset of "the whole of physics".
Similarly, EP is not some novel idea that can be just extracted from physics without breaking everything. If you conclude that EP is false, then you necessarily conclude that the physics that led to it is false. Once again, this does not help defend RET from scrutiny.
So what are these other contributing factors to their motion?
You are expected to develop an understanding of the basics before posting here. Please do so before continuing with the debate.
Post by: Groit on June 10, 2020, 09:11:10 PM
In FET all celestial bodies are accelerating at the same rateThis statement is false. Your issue stems from making poor assumptions.
All celestial bodies (that we know) share UA, but UA is not the only contributing factor to their motion. If it was, we'd perceive all celestial bodies as stationary relative to one another. Surely you knew this is not the case, so why waste our time with something so poorly thought out?
I'm talking about the stars. In FET the stars are in a layer just a few thousand km above the Earth, and at that distance, if they were not moving with the Earth then we would see their positions move in the sky and the constellations would change before our eyes. The stars must be accelerating at the same rate in FET, don't you think?
If we observe the light from stars that are directly above us, then we should observe a blueshift because the Earth has accelerated from time of emission to time observed on Earth and since Light travels at c in all reference frames then it would be blueshifted.
Post by: Pete Svarrior on June 10, 2020, 11:17:57 PM
The stars must be accelerating at the same rate in FET, don't you think?Given that the stars are in motion relative to an Earthbound observer, this is entirely impossible. I already told you that. Asking me again won't change this. If you disagree that we can observe stars moving relative to us, I can't really help you.
Your understanding of redshift and blueshift also appears to be fundamentally flawed, though you haven't been forthcoming enough for it to be completely clear how/why. Somehow, you're trying to tie it to acceleration relative to an external inertial observer rather than objects moving apart/closer together. You're also discussing the speed of the light instead of its wavelength. It's quite messy.
In FET the stars are in a layer just a few thousand km above the EarthI can't say I agree, but perhaps you're addressing a specific claim made by someone else. Nonetheless, your view that stars are motionless relative to the Earth is going to be a bit of a showstopper.
Post by: Bikini Polaris on June 11, 2020, 03:49:35 PM
That's at odds with the fact that the flat surface we would be on is now travelling upwards at quite a fast speed (incredibly greater than the speed of light).Please complete your assertion by answering the following question: Relative to what frame of reference?
Once your assertion has been made complete and coherent, please explain: How have you concluded this?
The frame of reference is irrelevant. If I'm accelerated in a direction and nothing is stopping me, I will acquire speed. In the wiki there's clearly written "Since the Earth is pushing you upwards, you are moving at the same speed as the Earth". So, that's the speed I'm talking about.
How do you conclude this? Well, again basing myself on the wiki, you just realize that if you never apply the Lorentz transformation, because you're not in a different system S' but you are on S, nothing prevents you from having a speed that is faster than light. In RE, a spaceship accelerating at 1g will eventually go faster than light and reach its destination as that was the case (but for the fact that time will have run faster at destination).
Another way to see this is that UA assumes the presence of an energy that act accelerating the earth. But energy is conserved, and so earth must acquire that energy in form of kinetic energy, and that's proportional to speed. The direction of the speed is, of course, 'upward'.
Post by: Groit on June 11, 2020, 05:38:09 PM
Your understanding of redshift and blueshift also appears to be fundamentally flawed, though you haven't been forthcoming enough for it to be completely clear how/why. Somehow, you're trying to tie it to acceleration relative to an external inertial observer rather than objects moving apart/closer together. You're also discussing the speed of the light instead of its wavelength. It's quite messy.
Its not messy, I'm talking about redshift/blueshift for uniform acceleration which is part of EP and is used as evidence to back UA.
For example, if we have a rocket accelerating at 1g away from any gravitational field with two observers onboard, with observer A at the front of the rocket and observer B at the back. If B sends a light signal to A then A will see the signal redshifted. If A sends a signal to B then B will see it blueshifted, even though both observers have remained the same distance apart.
(https://i.imgur.com/B30dOxw.png)
So if the Earth and the stars are accelerating at 1g due to UA, using the rocket anology, with the stars at the front of the rocket and the Earth at the back. The light from the stars directly above the Earth would be blueshifted and an observer on one of those stars would see the Earth being redshifted.
Post by: Pete Svarrior on June 11, 2020, 11:31:57 PM
The frame of reference is irrelevant.Incorrect. The frame of reference is absolutely crucial. If you believe it to be irrelevant, simply choose your favourite one. I'll give you a hint, there are three FoR's that are worth considering here: a local observer standing atop the Earth, a local observer located immediately above the Earth who is initally at rest relative to the Earth, and an external inertial observer.
If I'm accelerated in a direction and nothing is stopping me, I will acquire speed.Correct, but entirely irrelevant. The magnitude of that speed is the key point here, not the fact that it's increasing. Specifically, your claim that "the flat surface we would be on is now travelling upwards at quite a fast speed (incredibly greater than the speed of light)" contradicts basic physics. You cannot identify a frame of reference in which the Earth is moving faster than c without contradicting Special Relativity. As was the case previously, I suggest that throwing physics out the window is not the best way for you to defend RET.
because you're not in a different system S' but you are on SIf you're on S, your speed relative to S is 0m/s, and the speed of S relative to you is 0m/s. That's significantly lower than c.
Its not messy, I'm talking about redshift/blueshift for uniform acceleration which is part of EP and is used as evidence to back UA.So, here's the thing. I raised specific objections to what you're saying. Responding with nothing other than "it's not messy" is not going to cut it.
For example, if we have a rocket accelerating at 1g away from any gravitational field with two observers onboardThis is where you fail. The Doppler Effect is experienced when two bodies are in motion relative to one another. I already explained this to you, but you chose to ignore it. Two bodies accelerating upwards at the same rate and with no initial velocity will be stationary relative to one another. Thus, UA itself is not going to have any impact on the Doppler Effect.
The light from the stars directly above the Earth would be blueshifted and an observer on one of those stars would see the Earth being redshifted.This would be true if the stars were accelerating away from the Earth. As far as UA is concerned, they're not.
Post by: Bikini Polaris on June 12, 2020, 09:28:46 AM
The frame of reference is absolutely crucial. If you believe it to be irrelevant, simply choose your favourite one. I'll give you a hint, there are three FoR's that are worth considering here: a local observer standing atop the Earth, a local observer located immediately above the Earth who is initally at rest relative to the Earth, and an external inertial observer.
I said it's irrelevant because for an internal observer, the observed speed is zero (like it would be for an astronaut sitting on an accelerating spaceship) and, on the other hand, UA excludes the possibility of talking about "external" observers, let's say someone just below the place where an energy becomes acceleration, or someone outside the ice wall. UA is silent on the current knowledge of what is outside, but it doesn't deny it's existence, because it assumes that there is an energy the converts into movement in a direction.
If I'm accelerated in a direction and nothing is stopping me, I will acquire speed.Correct, but entirely irrelevant. The magnitude of that speed is the key point here, not the fact that it's increasing. Specifically, your claim that "the flat surface we would be on is now travelling upwards at quite a fast speed (incredibly greater than the speed of light)" contradicts basic physics. You cannot identify a frame of reference in which the Earth is moving faster than c without contradicting Special Relativity. As was the case previously, I suggest that throwing physics out the window is not the best way for you to defend RET.
Special Relativiy is safe, because what you cannot do is *measure* a speed faster than light in any frame of reference. But a traveller on a spaceship that is constantly accelerating at g toward a, let's say ten light years afar, star will reach it quicker than the speed of light, according *on the spaceship clock*, so it's indirectly a travel faster than the speed of light. The important difference with a travel that would really contradict SR is that the clocks on departure and destination will have run normally, that is faster than the spaceship clocks, and for them the spaceship has never went faster than the speed of light. But again, my main point is that the energy poured by the spaceship engines *must go somewhere*.
because you're not in a different system S' but you are on SIf you're on S, your speed relative to S is 0m/s, and the speed of S relative to you is 0m/s. That's significantly lower than c.
I'm referring to the whole system S, unknown-form-of-energy+earth-surface+the-visible-sky.
Summing up, I do understand that the whole UA describes the known universe as the inside of a spaceship, but still it doesn't rule out that fact that an energy is converting into acceleration in a direction. And this has, as a consequence, that we would *really* be on some sort of spaceship!
Post by: TomInAustin on June 12, 2020, 06:42:20 PM
What you felt when you fell was a brief experience of weightlessness/free-fall. This, too, can be colloquially described as "feeling acceleration", but it's a wholly distinct phenomenon. It sounds to me that by using an ambiguous term, you accidentally drew an equivalence between the two.
I think I can speak about freefall with as much or more authority than anyone here. I have 926 skydives and hold a master USPA D license. When one exits an aircraft moving through the air (90 to 100 mph on average) there are little to no feelings of acceleration. Mainly because it's a slow transition from 90 to 100 to 120 mph (average freefall speed) and that takes 9 seconds. However, when one starts falling from a very slow speed there is a huge feeling of acceleration. That gut thing like what you get on a roller coaster as it goes over that first drop. Out of 926 jumps all but 4 were regular moving airplanes to freefall to normal deployment. The 4 in question, one was from a hot air balloon, one from a helicopter in a near hover, and 2 low-speed* malfunctions that required cutting away the main and deploying the reserve. In each of these 4 examples, the feeling of falling was very dramatic, and nothing at all like hovering while the ground rushed up.
What would explain that? Yes, Einstein said acceleration and gravity produce the same effects but that does not come close to explaining why you can feel the acceleration.
* Low-speed malfunction is one where the canopy is deployed but not landable. A high-speed malfunction is one where there is not enough nylon deployed to slow you from freefall speeds. https://en.wikipedia.org/wiki/Malfunction_(parachuting)
Post by: pricelesspearl on June 12, 2020, 08:02:34 PM
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Special Relativiy is safe, because what you cannot do is *measure* a speed faster than light in any frame of reference. But a traveller on a spaceship that is constantly accelerating at g toward a, let's say ten light years afar, star will reach it quicker than the speed of light, according *on the spaceship clock*, so it's indirectly a travel faster than the speed of light.
This is proper velocity, or sometimes called celerity. Observer measured distance/elapsed time on the traveling clock. It has no limit.
Post by: Pete Svarrior on June 13, 2020, 05:01:39 AM
But a traveller on a spaceship that is constantly accelerating at g toward a, let's say ten light years afar, star will reach it quicker than the speed of light, according *on the spaceship clock*, so it's indirectly a travel faster than the speed of light.That has nothing go do with speed, and everything to do with spacetime.
What would explain that? Yes, Einstein said acceleration and gravity produce the same effects but that does not come close to explaining why you can feel the acceleration.Didn't we already discuss this in the part you've quoted? The feeling you've described is created by your inner ear, and is not exclusively tied to acceleration.
You say that "the feeling of falling was very dramatic, and nothing at all like hovering while the ground rushed up", but you have no way of contrasting the two. They are, as you've admitted, equivalent.
As for the acceleration component, you've already answered your own question. When you're close to terminal velocity, the forces at play are closed to balanced. The resultant acceleration you perceive is smaller than if you were accelerating downward at g relative to the Earth.
Post by: Groit on June 13, 2020, 05:57:38 PM
For example, if we have a rocket accelerating at 1g away from any gravitational field with two observers onboardThis is where you fail. The Doppler Effect is experienced when two bodies are in motion relative to one another. I already explained this to you, but you chose to ignore it. Two bodies accelerating upwards at the same rate and with no initial velocity will be stationary relative to one another. Thus, UA itself is not going to have any impact on the Doppler Effect.
I'm afraid this is where you fail Pete.
Two observers on a rocket accelerating at the same rate will indeed see the effects of Doppler shifts, Its part of GR and EP.
Have a look at the diagram below:
(https://i.imgur.com/5Hjcdnl.png)
For the accelerating rocket, observer A emits a photon at time
During the time from emission to receiving, observer B has accelerated so the distance for the photon to travel has increased to
And That distance is:
Since the distance has increased then observer B will see the light as redshifted.
The opposite effect happens when observer B emits a photon to observer A, the distance for the light to travel decreases given by:
Therefore observer A will see the light as blueshifted.
This is just the 'Equivalence Principle' at work and as you can see from the diagram both observers remain the same distance apart.
Post by: TomInAustin on June 15, 2020, 07:11:52 PM
What would explain that? Yes, Einstein said acceleration and gravity produce the same effects but that does not come close to explaining why you can feel the acceleration.Didn't we already discuss this in the part you've quoted? The feeling you've described is created by your inner ear, and is not exclusively tied to acceleration.
Yes, we did discuss it but I came to a new way of thinking about it. 4/900 is not a big sample size and I normally associate freefall with terminal velocities. Your explanation does not explain anything. The inner ear sensation of falling at the exact moment one starts falling seems pretty clear. If I was stationary and the ground came up to me I would feel nothing, but the perfect frame of reference is to be hanging in the air and cutting away to freefall.
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You say that "the feeling of falling was very dramatic, and nothing at all like hovering while the ground rushed up", but you have no way of
contrasting the two. They are, as you've admitted, equivalent.
How's this for a contrast? If I was in a stationary car and another car was 100 meters from me and started to accelerate towards me I would feel nothing, If the car I was in started to accelerate I would feel it. What am I missing?
This all sounds like a very Zetetic way to look at this.
Post by: Pete Svarrior on June 15, 2020, 10:45:05 PM
Two observers on a rocket accelerating at the same rateAt the same rate relative to what? In what direction? It's impossible to judge the correctness of your statement because it doesn't even come close to being complete. In the specific scenario you proposed (Earth and stars under UA), the Earth and stars are stationary relative to one another as far as UA is concerned. In other words, a=0.
Once again, you talk of speed, distance, and an individual photon (for which the concept of Doppler shifts is meaningless). You need to be talking about waves and wavelengths. Until you do so, you're not even discussing the Doppler effect in any meaningful fashion. There's a reason this failure is significant. As much as your upward acceleration will speed up the rate at which the waves hit you, the upward acceleration of the source will slow that rate down. If the two vectors are identical, the effect will cancel out. This is why the Doppler effect concerns the effect of the relative motion of two bodies on the wavelengths of the wave.
What am I missing?The air. A car accelerating towards you doesn't cause your entire surroundings to start zooming around you. The sensation of falling does.
Post by: Bikini Polaris on June 16, 2020, 01:59:17 PM
But a traveller on a spaceship that is constantly accelerating at g toward a, let's say ten light years afar, star will reach it quicker than the speed of light, according *on the spaceship clock*, so it's indirectly a travel faster than the speed of light.That has nothing go do with speed, and everything to do with spacetime.
Yeah. My point is that if something is above us and it's not "universally accelerated", or accelerated at less than 1 g upwards, we will arrive there pretty quickly (and we would crash with the incredible kinetic energy that we now have). That's the main problem an accelerating spaceship travelling the universe would have (after solving the energy problem etc...).
Post by: TomInAustin on June 16, 2020, 04:17:54 PM
What am I missing?The air. A car accelerating towards you doesn't cause your entire surroundings to start zooming around you. The sensation of falling does.
There is still no explanation of why you feel that sensation of falling. It makes no sense. Even with airflow. Freefall at terminal is a very noisy place but there is no sensation of falling at all. Only pre terminal.
Post by: Groit on June 16, 2020, 07:58:31 PM
Two observers on a rocket accelerating at the same rateAt the same rate relative to what? In what direction? It's impossible to judge the correctness of your statement because it doesn't even come close to being complete. In the specific scenario you proposed (Earth and stars under UA), the Earth and stars are stationary relative to one another as far as UA is concerned. In other words, a=0.
Once again, you talk of speed, distance, and an individual photon (for which the concept of Doppler shifts is meaningless). You need to be talking about waves and wavelengths. Until you do so, you're not even discussing the Doppler effect in any meaningful fashion. There's a reason this failure is significant. As much as your upward acceleration will speed up the rate at which the waves hit you, the upward acceleration of the source will slow that rate down. If the two vectors are identical, the effect will cancel out. This is why the Doppler effect concerns the effect of the relative motion of two bodies on the wavelengths of the wave.
I'm not sure you understand how the Equivalence Principle works where Doppler effects are concerned.
EP says that the gravitational redshifts / blueshifts observed near the surface of the Earth, is the same when observed inside a rocket accelerating with the same magnitude.
For example, if two observers on a rocket that's stood upright on the surface of the Earth were to send light pulses to one another, then the light detected at the top of the rocket will be Redshifted (longer wavelength) and the light received at the bottom will be blueshifted (shorter wavelength). This has been verified by the Pound–Rebka experiment.
The change in wavelength is given by:
Where
On the same rocket but now accelerating at 1g in space away from any gravity, light signals sent from the bottom and top of the rocket will be reshifted and blueshifted respectively.
The change in wavelength is given by:
Where
Light doesn't travel within reference frames, it propagates through space independently, however all observers in their reference frames will observe the light travelling at c. on the accelerated rocket, when light is emitted from the top of the rocket , then the bottom of the rocket is travelling towards it and thus will see it blueshifted (shorter wavelength).
Post by: omikun on June 18, 2020, 12:51:19 AM
Two observers on a rocket accelerating at the same rateAt the same rate relative to what? In what direction? It's impossible to judge the correctness of your statement because it doesn't even come close to being complete. In the specific scenario you proposed (Earth and stars under UA), the Earth and stars are stationary relative to one another as far as UA is concerned. In other words, a=0.
I think you have it exactly right. If UA is accelerating everything, the earth and stars are stationary relative to each other, and a=0. Like wise, we should be under the influence of UA, and we should experience a=0.
But when you drop a ball, that ball is not being accelerated by UA. The ground is, and it rushes up to the ball. When you pick a piece of dirt off the ground, that also is not accelerated by UA, so it too will "fall" when let go. In short, nothing that we know of on earth is accelerated by UA, only whatever underneath the known "earth" is accelerated by UA. If that is the case, UA isn't universal.
If UA is universal, we would all be floating about and feel no acceleration, because, as you say, a=0. Just as the stars and earth is stationary relative to each other, you, me, this keyboard, etc, we should all be stationary relative to each other.
Post by: Pete Svarrior on June 18, 2020, 08:55:18 AM
Freefall at terminal is a very noisy place but there is no sensation of falling at all. Only pre terminal.Well, yes, once you stop accelerating, your inner ear stops perceiving the effects of the air's acceleration relative to you. What... what exactly is your objection here?
Like wise, we should be under the influence of UA, and we should experience a=0.Incorrect. Please, at the very least read the article describing UA before posting here.
On the same rocket but now accelerating at 1g in space away from any gravityOnce again, for those in the back: the stars are not a rocket, and they are not accelerating away from the Earth. They are not moving away from the Earth, or at least are not doing so due to UA. As far as UA is concerned, the height of the stars relative to the Earth's surface remains static.
Your analogy would make some sense if you were to replace your source of gravity with an upward acceleration of a rocket. However, you're not doing that. You're adding more acceleration to the mix and acting surprised that your results have changed. That's not equivalence, now is it?
Wherea is 0. Therefore,is the acceleration
The Doppler effect occurs when two bodies are in motion relative to one another. Reference frames don't come into this. You can use one of the bodies as a frame of reference to help you simplify the task of drawing a diagram, but you can just as well do it from an external inertial FoR.
I would strongly suggest that you do this, even if just in your imagination. I'll borrow some diagrams from Wikipedia. Consider a source of waves like this:
(https://upload.wikimedia.org/wikipedia/commons/e/e3/Dopplereffectstationary.gif)
Now imagine it's moving away from you. Imagine the observer is located in the middle of the left-hand-side y axis. Whether the source accelerates or not is not important, since we're only discussing whether the effect is present at all, not its magnitude. The presence of relative motion will therefore be good enough.
(https://upload.wikimedia.org/wikipedia/commons/c/c9/Dopplereffectsourcemovingrightatmach0.7.gif)
You can, of course, see that a point on the left y axis would now observe a Doppler shift.
Finally, imagine that the point is not stationary on the y axis, but is rather moving in sync with the source. We can draw it from two perspectives. One of them uses the source as a frame of reference. That's just a repeat of the first diagram I've linked. But we can also draw it from an inertial perspective for your benefit.
(https://i.imgur.com/zoKGBbR.gif)
Even though the source is moving, so is the observer. Since their speeds are matched, the observer picks up the waves' peaks at the exact same rate as if both objects were stationary. Consequently, the wavelength is unchanged compared to the two objects being stationary within the inertial FoR.
The Doppler effect occurs when the source and observer are in motion relative to one another. The Equivalence Principle doesn't come into this. The two bodies are not in motion relative to one another (as far as UA is concerned), so there is no possible Doppler shift to be seen as a result of UA.
Post by: Groit on June 18, 2020, 02:25:50 PM
On the same rocket but now accelerating at 1g in space away from any gravityOnce again, for those in the back: the stars are not a rocket, and they are not accelerating away from the Earth. They are not moving away from the Earth, or at least are not doing so due to UA. As far as UA is concerned, the height of the stars relative to the Earth's surface remains static.
Your analogy would make some sense if you were to replace your source of gravity with an upward acceleration of a rocket. However, you're not doing that. You're adding more acceleration to the mix and acting surprised that your results have changed. That's not equivalence, now is it?Wherea is 0. Therefore,. I'll let you crunch the numbers from there.
The Doppler effect occurs when two bodies are in motion relative to one another. Reference frames don't come into this. You can use one of the bodies as a frame of reference to help you simplify the task of drawing a diagram, but you can just as well do it from an external inertial FoR.
I would strongly suggest that you do this, even if just in your imagination. I'll borrow some diagrams from Wikipedia. Consider a source of waves like this:
(https://upload.wikimedia.org/wikipedia/commons/e/e3/Dopplereffectstationary.gif)
Now imagine it's moving away from you. Imagine the observer is located in the middle of the left-hand-side y axis. Whether the source accelerates or not is not important, since we're only discussing whether the effect is present at all, not its magnitude. The presence of relative motion will therefore be good enough.
(https://upload.wikimedia.org/wikipedia/commons/c/c9/Dopplereffectsourcemovingrightatmach0.7.gif)
You can, of course, see that a point on the left y axis would now observe a Doppler shift.
Finally, imagine that the point is not stationary on the y axis, but is rather moving in sync with the source. We can draw it from two perspectives. One of them uses the source as a frame of reference. That's just a repeat of the first diagram I've linked. But we can also draw it from an inertial perspective for your benefit.
(https://i.imgur.com/zoKGBbR.gif)
Even though the source is moving, so is the observer. Since their speeds are matched, the observer picks up the waves' peaks at the exact same rate as if both objects were stationary. Consequently, the wavelength is unchanged compared to the two objects being stationary within the inertial FoR.
The Doppler effect occurs when the source and observer are in motion relative to one another. The Equivalence Principle doesn't come into this. The two bodies are not in motion relative to one another (as far as UA is concerned), so there is no possible Doppler shift to be seen as a result of UA.
Pete, all those diagrams you have used above are Doppler shifts for 'sound waves', so are not relevant for this discussion as we are talking about light waves. I suppose the last diagram is a little bit more on the lines but its still sound waves and the source and observer are travelling at constant speed they are nor accelerating.
It seems you are going against the Equivalence principle here Pete. I've just had a look on your wiki and it even states what I'm trying to explain to you, here:
Quote
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. ”
In the The Pound-Rebka Experiment light pulses were emitted from source to detector with a height of 22.5 m (note, source and detector are NOT moving relative to one another) and yet they detected a 'Doppler shift' due to gravity. Einstein's EP says that if you carry out the same experiment onboard a rocket accelerating at the same magnitude 1g, then you will see the same Doppler effects. Do you agree?
Post by: Pete Svarrior on June 18, 2020, 03:49:37 PM
Pete, all those diagrams you have used above are Doppler shifts for 'sound waves', so are not relevant for this discussion as we are talking about light waves.The Doppler effect applies to all waves. It applies to sound waves, light waves, ripples in a disturbed body of water, vibrations of a piece of string - waves. If you believe that sound waves would behave differently in your scenario, you'll have to state why. If you believe that the diagrams do not apply to the perception of light, please feel free to provide ones of your own which illustrate the same scenario, and highlight any corrections that you believe are necessary.
I suppose the last diagram is a little bit more on the lines but its still sound waves and the source and observer are travelling at constant speed they are nor accelerating.I already explained why this is irrelevant. One: the bodies are stationary relative to one another - this will not change if you accelerate the entire system. Two: we are discussing the presence of a Doppler shift, not its magnitude over time. As such, we only need to concern ourselves with the relative motion of the two bodies (or lack thereof, as the case may be). The magnitudes of said (non-)motion are irrelevant. If you disagree, you will have to state why. Specifically, you will have to address my position.
It seems you are going against the Equivalence principle here Pete.Not at all. You made two errors:
- You chose one two scenarios which are not equivalent: gravity, and gravity plus acceleration. This is incorrect. For EP to apply, the gravitational element would have to be absent in the second scenario.
- You assumed that the Doppler effect will occur between two bodies who are stationary to each other, as long as they're in motion relative to some other observer. This is a complete misunderstanding of the Doppler effect.
There is one more failure that I raised early on (https://forum.tfes.org/index.php?topic=16458.msg214157#msg214157), which I don't want you to forget just yet:
- You assume that UA is the only source of motion/acceleration of the stars relative to the Earth.
The Pound-Rebka ExperimentI already explained this to you several times. You're taking an experiment which concerns a gravity-free environment, thwacking it into an environment that is not gravity-free, and pondering super hard about why your results are not working out for you. You'd have to remove gravity/UA from your scenario to obtain reasonable results.
You cannot discuss RET vs FET with such an abysmal understanding of RET. Pick up a physics book and start learning. In the meantime, I'm not interested in more "nuh-uh!" responses. Either state your logic, or start improving your education.
Post by: Groit on June 18, 2020, 10:24:16 PM
I suppose the last diagram is a little bit more on the lines but its still sound waves and the source and observer are travelling at constant speed they are nor accelerating.I already explained why this is irrelevant. One: the bodies are stationary relative to one another - this will not change if you accelerate the entire system. Two: we are discussing the presence of a Doppler shift, not its magnitude over time. As such, we only need to concern ourselves with the relative motion of the two bodies (or lack thereof, as the case may be). The magnitudes of said (non-)motion are irrelevant. If you disagree, you will have to state why. Specifically, you will have to address my position.It seems you are going against the Equivalence principle here Pete.Not at all. You made two errors:
- You chose one two scenarios which are not equivalent: gravity, and gravity plus acceleration. This is incorrect. For EP to apply, the gravitational element would have to be absent in the second scenario.
- You assumed that the Doppler effect will occur between two bodies who are stationary to each other, as long as they're in motion relative to some other observer. This is a complete misunderstanding of the Doppler effect.
I will try to explain (again) how we can see Doppler shifts when two observers are stationary relative to one another in a uniform accelerating frame.
Einstein's elevator, have a look at this:
(https://i.imgur.com/mk5Ty4T.png)
(https://i.imgur.com/1vgswde.png)
If the Pound-Rebka experiment was carried out on the accelerating elevator away from any gravity then according to Einstein they would've had the same results with a Doppler shift z of
Using the Doppler shift formula in my earlier post you can see that the expected value for a Doppler shift in an accelerating frame where both observer are 22.6 m apart and do not move relative to one another is:
plug in the values to give
Not only would both observers see Doppler shifts, they would also see the effects of time dilation, the clock at the top of the elevator will tick faster that the one at the bottom one, which is same effects in gravity close to the surface of the Earth.
Are you winding me up Pete or what? ;)
link for the diagram: http://www.astro.ucla.edu/~wright/relatvty.htm
Post by: Pete Svarrior on June 20, 2020, 11:47:08 AM
I will try to explain (again) how we can see Doppler shifts when two observers are stationary relative to one another in a uniform accelerating frame.You don't need to keep re-explaining it. You need to fix the errors in your claims. I even provided you with a handy list. Are you going to get started, or are we done here?
Once again, in case you forgot: Your failure is not in thinking that UA should produce an identical shift to RET's gravity. Your failure is in thinking that it doesn't, or, to be more precise, that it's not being outweighed by factors external to UA. Your abysmal misuse of formulae doesn't help, but it's your lack of basic understanding that's leading you there in the first place. Start unraveling the failures I've listed and it'll click. If you don't want to, well, I can't force you.
Post by: Groit on June 20, 2020, 07:41:17 PM
I have just edited 4 of my posts in this thread that should have had diagrams. Here's my last post with the diagram that i thought was included before, and if you would like to go back to my previous posts (and any others interested) then it should become much clearer. Sorry about this.
I suppose the last diagram is a little bit more on the lines but its still sound waves and the source and observer are travelling at constant speed they are nor accelerating.I already explained why this is irrelevant. One: the bodies are stationary relative to one another - this will not change if you accelerate the entire system. Two: we are discussing the presence of a Doppler shift, not its magnitude over time. As such, we only need to concern ourselves with the relative motion of the two bodies (or lack thereof, as the case may be). The magnitudes of said (non-)motion are irrelevant. If you disagree, you will have to state why. Specifically, you will have to address my position.It seems you are going against the Equivalence principle here Pete.Not at all. You made two errors:
- You chose one two scenarios which are not equivalent: gravity, and gravity plus acceleration. This is incorrect. For EP to apply, the gravitational element would have to be absent in the second scenario.
- You assumed that the Doppler effect will occur between two bodies who are stationary to each other, as long as they're in motion relative to some other observer. This is a complete misunderstanding of the Doppler effect.
I will try to explain (again) how we can see Doppler shifts when two observers are stationary relative to one another in a uniform accelerating frame.
Einstein's elevator, have a look at this:
(https://i.imgur.com/mk5Ty4T.png)
(https://i.imgur.com/1vgswde.png)
If the Pound-Rebka experiment was carried out on the accelerating elevator away from any gravity then according to Einstein they would've had the same results with a Doppler shift z of
Using the Doppler shift formula in my earlier post you can see that the expected value for a Doppler shift in an accelerating frame where both observer are 22.6 m apart and do not move relative to one another is:
plug in the values to give
Not only would both observers see Doppler shifts, they would also see the effects of time dilation, the clock at the top of the elevator will tick faster that the one at the bottom one, which is same effects in gravity close to the surface of the Earth.
Are you winding me up Pete or what? ;)
link for the diagram: http://www.astro.ucla.edu/~wright/relatvty.htm
Post by: Groit on June 20, 2020, 10:37:19 PM
Not at all. You made two errors:
- You chose one two scenarios which are not equivalent: gravity, and gravity plus acceleration. This is incorrect. For EP to apply, the gravitational element would have to be absent in the second scenario.
Where did i say gravity plus acceleration?
- You assumed that the Doppler effect will occur between two bodies who are stationary to each other, as long as they're in motion relative to some other observer. This is a complete misunderstanding of the Doppler effect.
Pete, two observers that are stationary to each other in an accelerating frame, away from any gravity, really do see the Doppler effect. Its part of the equivalence principle. Have a look at the diagrams i just recently added. If you are saying this is wrong, then you are saying Einstein is wrong also.
There is one more failure that I raised early on (https://forum.tfes.org/index.php?topic=16458.msg214157#msg214157), which I don't want you to forget just yet:
- You assume that UA is the only source of motion/acceleration of the stars relative to the Earth.
Once you've tidied up your messy claims, resolving this failure will finally eliminate all outstanding contradictions.
Lets forget about the stars for now and just concentrate on the Earth. In FET the Earth is accelerating upwards at 1g correct? If this was true then not only would we observe Doppler shifts equivalent to a gravitational redshift which has been verified in many experiments such as the Pound-Rebka experiment, but we would also observe a redshift / blueshift drift that will be time dependent.
This is one difference between gravity and acceleration and the 'equivalence principle' only holds from the first moments of acceleration.
Here's a diagram showing the redshift drift for uniform accelerating frames, and also a link to the paper which is from a good source. The math gets pretty intense for further reading, because it talks about Rindler coordinates etc and i don't think any of us on here are experts in GR are we? anyway the first section should be enough to get the drift. ;)
(https://i.imgur.com/ONQ0XW4.png)
https://arxiv.org/pdf/1907.06332.pdf
[/list][/list]
Post by: Pete Svarrior on June 21, 2020, 12:03:40 AM
Where did i say gravity plus acceleration?Every time you describe "a rocket accelerating away from any gravity". In other words: all the time, everywhere, without respite.
Pete, two observers that are stationary to each other in an accelerating frame, away from any gravity, really do see the Doppler effect.Right, but that's not the signifciant factor in the shift you're observing from the stars. I pointed this out very early on, so there's no way you could possibly still be rambling about that. You're talking about the shift that supposedly contradicts observation. Hint: it doesn't, and as soon as you've tidied up your mess, that much will be obvious.
Lets forget about the stars for now and just concentrate on the Earth.No, let's not. I'm not interested in your excuses and diversions. Fix your messy claims. If you do not want to take responsibility for your failures, then stop wasting our time.
Post by: Groit on July 04, 2020, 10:44:40 PM
Lets forget about the stars for now and just concentrate on the Earth.No, let's not. I'm not interested in your excuses and diversions. Fix your messy claims. If you do not want to take responsibility for your failures, then stop wasting our time.
We don't need to use the stars, as we could perform an experiment at the Earth's surface to determine whether we are accelerating due to 'gravity' or 'UA'.
In fact the Pound-Rebka (and more recent) experiments have done just that.
These experiments were carried out to test GR and show that light will lose or gain energy in a gravitational field depending which way the photons are emitted and received. For the Pound-Rebka experiment, photons were dropped from a height of 22.6 m towards the surface of the Earth and they successfully detected a blueshift close to the predicted value.
This experiment was repeated many times over long periods and always gave the same results with a blueshift (z) of:
If the Pound-Rebka experiment was carried out in an accelerating frame (without gravity) such as a rocket or in this case the Earth accelerating upwards (UA), then the results would be somewhat different. This is due to the 'blueshift drift' effect for accelerating frames. The formula for the expected z values is given by:
The plot below shows blueshift (z) against time, if the same experiment was carried out in gravity (red line) and an accelerating frame such as UA (blue line). For the accelerating frame, we have blueshift drift, and for gravity no blueshift drift would be detected. The time axis is in seconds and goes to six months.
(https://i.imgur.com/crCSZ2hl.png)
The Pound-Rebka (and other) experiments never detected any blueshift drift over time, therefore we must be in a gravitational field.
Using the Equivalence Principle as evidence to support UA is fine for things like how objects fall, projectile motion etc... but when it comes to the nature of light and how we observe its Doppler shifts over periods of time then it no longer holds. This flaw within the Equivalence Principle is a way to distinguish between an accelerating frame and gravity.
Post by: Pete Svarrior on July 04, 2020, 10:46:35 PM
We don't need to use the starsNo, no, let's not change your claims. Let's simply correct the errors within. You were provided with a list. Get on with it.
And no, your core failure continues to become more pronounced every time you post. You assume that the only source of Doppler shitfts in light is UA/gravity, or that you can somehow isolate it within an Earth-bound observation. It isn't, and you can't.
Post by: Jeb Kermin on July 13, 2020, 11:14:07 PM
If the Pound-Rebka experiment was carried out in an accelerating frame (without gravity) such as a rocket or in this case the Earth accelerating upwards (UA), then the results would be somewhat different. This is due to the 'blueshift drift' effect for accelerating frames. The formula for the expected z values is given by:which is time dependent.
The plot below shows blueshift (z) against time, if the same experiment was carried out in gravity (red line) and an accelerating frame such as UA (blue line). For the accelerating frame, we have blueshift drift, and for gravity no blueshift drift would be detected. The time axis is in seconds and goes to six months.
Using the Equivalence Principle as evidence to support UA is fine for things like how objects fall, projectile motion etc... but when it comes to the nature of light and how we observe its Doppler shifts over periods of time then it no longer holds. This flaw within the Equivalence Principle is a way to distinguish between an accelerating frame and gravity.
Hmm, but I thought the idea of the EP, was that there was no local experiment you can do which differentiated between free fall and an accelerating frame relative to some observer who is not accelerating or experiencing free fall.
Now the catch here is "local", because as gravity falls off with the square of the distance, the acceleration is not constant, so your experiment/measurement has to take this into account. Was that the point of the experiment ?
This leads to another hypothetical experiment, which might be a bit easier to understand. I was reading the Wiki on UA. Apparently the "gravitational anomalies" as determined by things like scale measurements are dismissed out of hand because the scales aren't re calibrated (which is kind of the point, but lets ignore that for now)
I don't see a claim whehter UA is predicting an acceleration which is invariant with altitude, or makes some attempt to account for it, if it can be observed.
Edit: Sorry, there does appear to be a reference to "Celestial gravitation" which causes the acceleration to fall off with altitude, so apparently some celestial bodies exhibit gravitational pull but apparently it does not apply to Earth, at least not the same way). However, I can't find how this would be quantified. Gravitational theory predicts that g should fall off with altitude, with the square of the distance between the two bodies.
I'm wondering if an experiment whereby free fall was measured, with say with a ball bearing in a vacuum tube, perhaps suspended by an electromagnet, released with electronics which was tied to a precise timer which is demagnetizes and stops when a sensor at the bottom is hit.
In constant acceleration, the velocity v = a * t, assuming initial velocity 0. Which means the position, we'll call height h, is the antideriviative, so is h = 0.5 * a * t^2, again assuming initial height of 0. Solving for t, we get t = sqrt(h / (0.5 * a))
If the tube were 1 m, then at the surface of the Earth (g = 9.806 m/s^2), the free fall time should be the sqrt (1 m /(0.5 * 9.806 m/s^2)) = 0.4516 s, or 451.6 ms. At an altitude of 10 km, which is typical of airlines flight, g is predicted to be closer to 9.776 m/s^2, which yields a drop time of 1/(0.5 * 9.776 m/s^2) = 452.3 ms, so a difference of 0.7 ms. Not exactly easy to measure, but with decent electronics, shouldn't be hard at all, as its only a frequency of ~1500 Hz.
Of course we would have to be sure the plane is not accelerating, and that the tube was perfectly level.
Post by: ljman on July 14, 2020, 09:17:15 PM
Quote
Hmm, but I thought the idea of the EP, was that there was no local experiment you can do which differentiated between free fall and an accelerating frame relative to some observer who is not accelerating or experiencing free fall
The local aspect of the equivalence principle is mentioned, but is pretty glossed over. I'd be interested in how flat earthers define "locally"