The Flat Earth Society
Flat Earth Discussion Boards => Flat Earth General => Topic started by: Paranoid on October 22, 2011, 03:39:35 PM
-
Sorry if this has been asked before, I used the search function but couldn't find anything.
This question is regarding the feeling all humans get when falling from a height. We've all (I assume) felt this before, jumping from a high, we get that feeling in our guts that we are falling and we wouldnt need to see what's happening to feel this as its acting on us.
If gravity works in the way the flat earth theory says, which to my understanding is that objects dont move towards the earth, the earth is constantly accellerating, the earth moves "up" to meet the object.
This would mean that a human that has jumped from a height isnt moving at all, so how is the feeling produced?
-
It is psychologic yes? Because that is the expression for the jump. So people in mind are believe.
-
The feeling of being accelerated upwards is "normal". The absence of this acceleration is the feeling you describe.
This has to do with contact forces. It is no different for a flat or round earth.
-
It is psychologic yes? Because that is the expression for the jump. So people in mind are believe.
No no, I'm refering to a physical reaction, its the same mechanisms that alert you when you've lost your balance, to help correct you.
The feeling of being accelerated upwards is "normal". The absence of this acceleration is the feeling you describe.
This has to do with contact forces. It is no different for a flat or round earth.
Hmm, interesting. Deffinitly a take on it I had not considered. Food for thought!
-
The feeling of being accelerated upwards is "normal". The absence of this acceleration is the feeling you describe.
Thanks to the equivalence principle, we can just as readily say that the feeling of being pulled down by gravity is "normal".
-
No, markjo. Thanks to the equivalence principle, we can just as readily say that the earth is accelerating us upwards on either a flat or round earth.
On a round earth the person falling is still being pulled down by the mythical force of gravity. This would not account for the "normal" sensation.
-
No, markjo. Thanks to the equivalence principle, we can just as readily say that the earth is accelerating us upwards on either a flat or round earth.
On a round earth the person falling is still being pulled down by the mythical force of gravity. This would not account for the "normal" sensation.
I'm afraid you have misunderstood the equivalence principle. It states that the effects of gravity are locally indistinguishable from those of a constant acceleration. A world where the Earth is accelerated upwards towards an object is locally indistinguishable from a world where an object and the Earth are accelerated towards each other by gravity.
However, it is easy to see that such a force accelerating the Earth is impossible due to the conservation of momentum and Energy. So you seem to have it mixed up, UA is a mythical force that pushes the Earth up.
-
Experiment: Get up on a chair and walk off the edge.
When you go into free-fall and observe the earth carefully, you can see that the earth is moving upwards. You do not see anything pulling you down towards the earth. It's absurd to believe that invisible puller particles/bendy space are responsible for your experiences when one can see, directly, that the earth is accelerating upwards.
Why believe in the invisible when the visible is an alternative explanation? This is why the concept of an upwardly accelerating earth is a stronger argument.
-
Experiment: Get up on a chair and walk off the edge.
When you go into free-fall and observe the earth carefully, you can see that the earth is moving upwards. You do not see anything pulling you down towards the earth. It's absurd to believe that invisible puller particles/bendy space are responsible for your experiences when one can see, directly, that the earth is accelerating upwards.
Why believe in the invisible when the visible is an alternative explanation? This is why the concept of an upwardly accelerating earth is a stronger argument.
In RE you have invisible puller particles, in FE you have invisible pusher particles. Both sound equally odd. But since gravity matches observations better than UA, we are brought to the conclusion that the Earth is in fact round.
-
I'm afraid you have misunderstood the equivalence principle. It states that the effects of gravity are locally indistinguishable from those of a constant acceleration. A world where the Earth is accelerated upwards towards an object is locally indistinguishable from a world where an object and the Earth are accelerated towards each other by gravity.
This is true, as far as it goes.
However, it is easy to see that such a force accelerating the Earth is impossible due to the conservation of momentum and Energy. So you seem to have it mixed up, UA is a mythical force that pushes the Earth up.
There is no force acting on a falling body. Take a sky diver, for example, Paranoid has suggested. If we give him an accelerometer and observe it during his "falling sensation" there is no acceleration measured (neglecting perhaps a small measured upward-acceleration due to air resistance).
However, when we place this accelerometer on the earth below him, we measure an upward-acceleration of approximately 9.8 meters per second per second.
The only force measured is an upward acceleration. The equivalence principle is globularism's desperate attempt to explain it away.
-
In RE you have invisible puller particles, in FE you have invisible pusher particles. Both sound equally odd.
Why does whatever is pushing the earth need to be invisible? Pusher particles don't sound odd. Puller particles sound odd. How can a particle pull?
But since gravity matches observations better than UA, we are brought to the conclusion that the Earth is in fact round.
Gravity doesn't match observations. No one has seen gravity. But everyone can see the upwards movement of the earth.
-
In RE you have invisible puller particles, in FE you have invisible pusher particles. Both sound equally odd.
Why does whatever is pushing the earth need to be invisible? Pusher particles don't sound odd. Puller particles sound odd. How can a particle pull?
You aren't aware of any force that pulls objects toward it?
-
The equivalence principle is globularism's desperate attempt to explain it away.
Say's the man who claims celestial objects have gravitation to explain local differences in acceleration.
Why does whatever is pushing the earth need to be invisible? Pusher particles don't sound odd. Puller particles sound odd. How can a particle pull?
I'm pretty sure positively charged particles can pull negatively charged particles...
-
I'm afraid you have misunderstood the equivalence principle. It states that the effects of gravity are locally indistinguishable from those of a constant acceleration. A world where the Earth is accelerated upwards towards an object is locally indistinguishable from a world where an object and the Earth are accelerated towards each other by gravity.
This is true, as far as it goes.
However, it is easy to see that such a force accelerating the Earth is impossible due to the conservation of momentum and Energy. So you seem to have it mixed up, UA is a mythical force that pushes the Earth up.
There is no force acting on a falling body. Take a sky diver, for example, Paranoid has suggested. If we give him an accelerometer and observe it during his "falling sensation" there is no acceleration measured (neglecting perhaps a small measured upward-acceleration due to air resistance).
However, when we place this accelerometer on the earth below him, we measure an upward-acceleration of approximately 9.8 meters per second per second.
The only force measured is an upward acceleration. The equivalence principle is globularism's desperate attempt to explain it away.
The equivalence principle is an empirical fact derived from logic and physical observation. It's not an attempt (desperate or otherwise), it is a success both theoretically and physically. The fact that you are attacking one of the only mechanisms under which a FE might be possible shows how desperate your attempt is.
-
In RE you have invisible puller particles, in FE you have invisible pusher particles. Both sound equally odd.
Why does whatever is pushing the earth need to be invisible? Pusher particles don't sound odd. Puller particles sound odd. How can a particle pull?
But since gravity matches observations better than UA, we are brought to the conclusion that the Earth is in fact round.
Gravity doesn't match observations. No one has seen gravity. But everyone can see the upwards movement of the earth.
If they exist, the puller particles must be fairly hard to see since they've never been observed. Also, puller particles are very much possible. For example, two oppositely charged particles will pull on each other. This attraction is understood to be an exchange of virtual photons the constitute the electromagnetic force.
-
The equivalence principle is an empirical fact derived from logic and physical observation. It's not an attempt (desperate or otherwise), it is a success both theoretically and physically. The fact that you are attacking one of the only mechanisms under which a FE might be possible shows how desperate your attempt is.
I think you greatly misunderstand. Einstein himself posited your gravitation as a fictitious force, building from the D’Alembert principle. He knew that there was no detectable force on an object in freefall. His only recourse was to postulate the bending of space-time to account for the apparent acceleration of the falling body. D'Alembert's principle and the Equivalence principle are both true as far as they go.
-
The equivalence principle is an empirical fact derived from logic and physical observation. It's not an attempt (desperate or otherwise), it is a success both theoretically and physically. The fact that you are attacking one of the only mechanisms under which a FE might be possible shows how desperate your attempt is.
I think you greatly misunderstand. Einstein himself posited your gravitation as a fictitious force, building from the D’Alembert principle. He knew that there was no detectable force on an object in freefall. His only recourse was to postulate the bending of space-time to account for the apparent acceleration of the falling body. D'Alembert's principle and the Equivalence principle are both true as far as they go.
You're right... as far as you go. The EP means that gravity can be seen locally as an acceleration. For example, if a friend (a few feet away) and I calculated our respective acceleration vectors they would point in same direction; in the small region of space that my friend and I are in, the gravitational field can be replaced by an acceleration Earth and no differences could be discerned. However, if my friend were to travel to the other side of the world and we repeated our calculations, we would find that our acceleration vectors point in opposite directions; in this case the EP no longer holds and the effects of gravity and a constant acceleration are radically different.
-
Gravitation would affect all mass including both masses in an accelerometer, eliminating any measured weight within the accelerometer. Consider an accelerometer made entirely out of iron being pulled by a magnetic field. Stick this device on the bottom of a magnet and it will measure downward acceleration, but of course it would be doing no such thing. This is because accelerometers work by resisting acceleration. If the entire device is not resisting gravitation or magnetism, it will not read a force.
-
Experiment: Get up on a chair and walk off the edge.
When you go into free-fall and observe the earth carefully, you can see that the earth is moving upwards. You do not see anything pulling you down towards the earth. It's absurd to believe that invisible puller particles/bendy space are responsible for your experiences when one can see, directly, that the earth is accelerating upwards.
No offense but thats a pretty terrible way of going about an experiment. All you would observe from that is you and the ground/earth meeting. To draw a conclusion that "The earth moves towards your stationary self" is what is absurd.
I didn't even realise this thread would keep going. hehe
-
You do not see anything pulling you down towards the earth. It's absurd to believe that invisible puller particles/bendy space are responsible for your experiences when one can see, directly, that the earth is accelerating upwards.
How do microwaves work?
-
You do not see anything pulling you down towards the earth. It's absurd to believe that invisible puller particles/bendy space are responsible for your experiences when one can see, directly, that the earth is accelerating upwards.
How do microwaves work?
Ya put the frozen dinner in, set the timer, and a yummy meal comes out. That's all you need to know, according to NASA, the ninjas, and the fairies.
-
Experiment: Get up on a chair and walk off the edge.
When you go into free-fall and observe the earth carefully, you can see that the earth is moving upwards. You do not see anything pulling you down towards the earth. It's absurd to believe that invisible puller particles/bendy space are responsible for your experiences when one can see, directly, that the earth is accelerating upwards.
When I drive down the street in my car, are the buildings really moving towards me instead of me moving towards them? Really? Then how does my steering wheel move the building out of the way? I would really like to know, Tom. I think it would be absurd to believe that.
-
The equivalence principle is an empirical fact derived from logic and physical observation. It's not an attempt (desperate or otherwise), it is a success both theoretically and physically. The fact that you are attacking one of the only mechanisms under which a FE might be possible shows how desperate your attempt is.
I think you greatly misunderstand. Einstein himself posited your gravitation as a fictitious force, building from the D’Alembert principle. He knew that there was no detectable force on an object in freefall. His only recourse was to postulate the bending of space-time to account for the apparent acceleration of the falling body. D'Alembert's principle and the Equivalence principle are both true as far as they go.
You are not quite understanding Einstein either. To quote from Warren on physicsforums.com, since he says it better than I could;
In the parlance of general relativity, gravity is not a force. The only situations that forces are involved are those situations in which a body is not allowed to follow its natural trajectory. The chair you're sitting on is preventing you from following the trajectory you'd otherwise follow, onto the ground. When you're freely falling, you don't feel your own weight, which means no forces are acting upon you.
Yes Einstein did not consider an object in freefall to be subject to "forces" as such, but no, he did not take this to be a refutating of gravity. Gravity is not a force, it's more to do with the "shape" of space. In the analogous manner, when travelling up a hill the shape of the hill is not a force pushing you upwards, yet you ARE moving upwards. But we don't call hills "forces".
-
No, markjo. Thanks to the equivalence principle, we can just as readily say that the earth is accelerating us upwards on either a flat or round earth.
On a round earth the person falling is still being pulled down by the mythical force of gravity. This would not account for the "normal" sensation.
The feeling of weightlessness is what causes the "falling" sensation; specifically in the stomach, where weightlessness is more evident to the human senses. So In either FE or RE scenarios a "falling" sensation will be felt when in freefall.
-
No, markjo. Thanks to the equivalence principle, we can just as readily say that the earth is accelerating us upwards on either a flat or round earth.
On a round earth the person falling is still being pulled down by the mythical force of gravity. This would not account for the "normal" sensation.
The feeling of weightlessness is what causes the "falling" sensation; specifically in the stomach, where weightlessness is more evident to the human senses. So In either FE or RE scenarios a "falling" sensation will be felt when in freefall.
I agree. I was refuting markjo's interpretation of the data.
I think you greatly misunderstand. Einstein himself posited your gravitation as a fictitious force, building from the D’Alembert principle. He knew that there was no detectable force on an object in freefall. His only recourse was to postulate the bending of space-time to account for the apparent acceleration of the falling body. D'Alembert's principle and the Equivalence principle are both true as far as they go.
You are not quite understanding Einstein either.
I don't think I did misunderstand. There is nothing in the quote you provided that disagrees with what I stated.
-
I think you greatly misunderstand. Einstein himself posited your gravitation as a fictitious force, building from the D’Alembert principle. He knew that there was no detectable force on an object in freefall. His only recourse was to postulate the bending of space-time to account for the apparent acceleration of the falling body. D'Alembert's principle and the Equivalence principle are both true as far as they go.
You are not quite understanding Einstein either.
I don't think I did misunderstand. There is nothing in the quote you provided that disagrees with what I stated.
The point is that Einstein was not proposing that Gravity was fictitious at all, only that it is not a force as such. If you think that he was, then you fail to understand The Theory of Relativity.
-
What about my post inclines you to believe I said something contrary to your post?
-
What about my post inclines you to believe I said something contrary to your post?
I understood you to be inferring that gravity is not acting on a falling body. You then claimed that Einstein called gravity a fictitious force which is not correct or at best missing the point. It may not be called a 'force' in the context of relativity, but that is quite a different thing to claiming gravity doesn't exist. Einstein most definitely believed in gravity.
And as far as Newtonian Mechanics is concerned, the affect of gravity is an observable force, whether it actually is a force or not is more an issue of semantics.
-
I said there is no measurable force being applied to a falling body. Einstein did call gravitation a fictitious force. He postulated that we exist in non-inertial frames of reference. If relativity were to be true, it would be a fictitious force by definition. Perhaps you should read up on fictitious forces.
As far as Newtonian Mechanics is concerned gravity is a force. Newtonian Gravity assumes inertial frames of reference.
-
I said there is no measurable force being applied to a falling body. Einstein did call gravitation a fictitious force. He postulated that we exist in non-inertial frames of reference. If relativity were to be true, it would be a fictitious force by definition. Perhaps you should read up on fictitious forces.
As far as Newtonian Mechanics is concerned gravity is a force. Newtonian Gravity assumes inertial frames of reference.
You use the term ficticious to insinuate something that doesn't exist. The term ficticious force refers to an inertial force. It's real and it exists, but it's not a force that acts on the body, it is an apparent force that manifests when a body undergoes acceleration. Centrifugal force is also a ficticious force, are you going to say that the centrifugal affect is not real?
When you accelerate in a car, there is an apparent force pushing you back in your seat. You can't measure that either, there is nothing pushing on you at all, yet the fact remains SOMETHING is pressing you into the seat.
Gravity is real. It causes an apparent force to act on bodies within it's field.
You are arguing semantics, the bottomline is that gravity is a well measured phenomenon and even though it's not known what actually causes gravity, it's affects are well understood and offer a far better explanation than UA (the cause of which is even less understood) for the shape of the earth and for the phenomena of 'falling'.
-
Gravity is a dis-proven theory, and gravitation stands not much better. That gravitation exists in some form, I am prepared to grant. I never said that gravitation was fictitious. Only that Einstein posited that his own form of gravitation was a fictitious force. Whether you decided to argue in ignorance or just to disagree, I do not care.
-
Gravity is a dis-proven theory, and gravitation stands not much better. That gravitation exists in some form, I am prepared to grant. I never said that gravitation was fictitious. Only that Einstein posited that his own form of gravitation was a fictitious force. Whether you decided to argue in ignorance or just to disagree, I do not care.
Your understanding of the use of the term fictitious is flawed. It's not gravity, or it's affects, that are being called fictitious, but it's manifestation as a force. In curved space/time, something can appear to be affected by a force when it isn't.
Regarding the so called disproof of gravity, it is not gravity that has been disproved, but the theory of how gravity works ie: in light of discoveries in quantum mechanics, the previous theory of gravity has been shown to be incomplete. This is no different essentially to how Einstein's Theory of Relativity modified Newtonian Gravity.
The Theory of Gravity as elucidated by Relativity was not 'disproved' until 2004. This was long after Einstein's death and his statement about fictitious forces was not meant to imply Gravity didn't exist. His Theory of Gravity was compatible with the idea of fictitious forces infact it was the idea that Gravity might be fictitious (inertial) that led him on to develop a theory of gravity. The idea also forms the basis for General Relativity.
Neither Einstein's Theory of Gravity nor his Theory of General Relativity are disproved by quantum field discoveries; rather they have been found to be incomplete and in need of modification to work at a quantum level.
The other three base forces of nature have been reconciled with quantum mechanics, the fact that gravity has not yet been reconciled means nothing.
We can argue about it all day, but the fact remains you cannot claim that Einstein's work somehow supports the proposition that the Earth rushes up to meet you when you step off a chair.
-
I'm not sure if you're being deliberately obtuse or if your desire to argue is overcoming your reading comprehension.
-
Ok, explain this. If gravity really is the earth moving upwards, why is it that Canada has a section that has less gravity than the rest of the world. Is that part accelerating slower?
And what about the earths magnetic field? Is magnetic north just a figment of our imagination or was it somehow put there by the "conspiracy?"
-
I'm not sure if you're being deliberately obtuse or if your desire to argue is overcoming your reading comprehension.
If you can't understand what I'm saying just say so don't accuse me of being obtuse...
If you are claiming that Einstein refuted gravity then we have something to continue to argue about, if not, then I must have misunderstand where you are coming from.
If it's the former, and you can't grasp the fact that "fictitious" as used by Einstein does not mean "the affect doesn't exist" then you need to read a little more yourself. The centrifugal force is also "fictitious" yet you can't deny it's affect any time you go around a corner in a car. The affect is real, and it's due to inertia, not due to a force, hence it can't be measured in the classical way that a force would be measured.
-
I'm not sure if you're being deliberately obtuse or if your desire to argue is overcoming your reading comprehension.
If you are claiming that Einstein refuted gravity then we have something to continue to argue about, if not, then I must have misunderstand where you are coming from.
Then you have misunderstood. Einstein is refuting gravity, but obviously not gravitation.
-
I'm not sure if you're being deliberately obtuse or if your desire to argue is overcoming your reading comprehension.
If you are claiming that Einstein refuted gravity then we have something to continue to argue about, if not, then I must have misunderstand where you are coming from.
Then you have misunderstood. Einstein is refuting gravity, but obviously not gravitation.
grav·i·ty
noun, often attributive \ˈgra-və-tē\
plural grav·i·ties
Definition of GRAVITY
1
a : dignity or sobriety of bearing b : importance, significance; especially : seriousness c : a serious situation or problem
2
: weight
3
a (1) : the gravitational attraction of the mass of the earth, the moon, or a planet for bodies at or near its surface (2) : a fundamental physical force that is responsible for interactions which occur because of mass between particles, between aggregations of matter (as stars and planets), and between particles (as photons) and aggregations of matter, that is 10-39 times the strength of the strong force, and that extends over infinite distances but is dominant over macroscopic distances especially between aggregations of matter —called also gravitation, gravitational force — compare electromagnetism 2a, strong force, weak force b : acceleration of gravity c : specific gravity
http://www.merriam-webster.com/dictionary/gravity (http://www.merriam-webster.com/dictionary/gravity)
-
I'm not sure if you're being deliberately obtuse or if your desire to argue is overcoming your reading comprehension.
If you are claiming that Einstein refuted gravity then we have something to continue to argue about, if not, then I must have misunderstand where you are coming from.
Then you have misunderstood. Einstein is refuting gravity, but obviously not gravitation.
grav·i·ty
noun, often attributive \ˈgra-və-tē\
plural grav·i·ties
Definition of GRAVITY
1
a : dignity or sobriety of bearing b : importance, significance; especially : seriousness c : a serious situation or problem
2
: weight
3
a (1) : the gravitational attraction of the mass of the earth, the moon, or a planet for bodies at or near its surface (2) : a fundamental physical force that is responsible for interactions which occur because of mass between particles, between aggregations of matter (as stars and planets), and between particles (as photons) and aggregations of matter, that is 10-39 times the strength of the strong force, and that extends over infinite distances but is dominant over macroscopic distances especially between aggregations of matter —called also gravitation, gravitational force — compare electromagnetism 2a, strong force, weak force b : acceleration of gravity c : specific gravity
http://www.merriam-webster.com/dictionary/gravity (http://www.merriam-webster.com/dictionary/gravity)
They aren't the same except in common speech. Merriam webster isn't an appropriate source for this.
From what little I've read of this thread, ski is correct.
Gravity is a pseudoforce. Objects travel their inertial paths. When something falls, it goes in a straight line.
-
When something falls, it goes in a straight line.
Or a parabola.
-
When something falls, it goes in a straight line.
Or a parabola.
Nope, always a straight line unless acted upon by a real force.
-
When something falls, it goes in a straight line.
Or a parabola.
Nope, always a straight line unless acted upon by a real force.
If that is true and gravity doesn't count as a "real" force, then it must be concluded that the only way that objects can travel in "straight lines" that matches everyday experience, it must be concluded that space must be warping.
-
When something falls, it goes in a straight line.
Or a parabola.
Nope, always a straight line unless acted upon by a real force.
If that is true and gravity doesn't count as a "real" force, then it must be concluded that the only way that objects can travel in "straight lines" that matches everyday experience, it must be concluded that space must be warping.
Correct.
Gravity isn't a real force in relativity. That has been the whole point of the last page of posts. Its a pseudoforce or ficticious force. And yes "space is warping" so to speak. Things travel their inertial path (a straight line).
-
When something falls, it goes in a straight line.
Or a parabola.
Nope, always a straight line unless acted upon by a real force.
Think about projectile motion. A rock thrown by a trebuchet, once released, has no forces acting on it except air resistance, which is minimal. The rock follows a parabolic arc, as it's both accelerating towards the ground, and moving at a constant horizontal speed.
-
When something falls, it goes in a straight line.
Or a parabola.
Nope, always a straight line unless acted upon by a real force.
Think about projectile motion. A rock thrown by a trebuchet, once released, has no forces acting on it except air resistance, which is minimal. The rock follows a parabolic arc, as it's both accelerating towards the ground, and moving at a constant horizontal speed.
I'm sorry, but it only follows a parabolic arc from an inertial frame of reference. From a non-inertial stand-point it travels in a straight line.
-
I'm sorry, but it only follows a parabolic arc from an inertial frame of reference. From a non-inertial stand-point it travels in a straight line.
I think I know what you're trying to say, but I understand it to be the other way around. Taking an accelerating earth, for example, the earth itself is a non-inertial frame as it is accelerating. From this non-inertial frame, the rock follows the parabola. From an inertial frame, say, another rock thrown straight up, the original rock appears to move straight horizontally. Also, from the original rock's inertial frame of reference, the earth is following a parabolic trajectory.
-
I'm sorry, but it only follows a parabolic arc from an inertial frame of reference. From a non-inertial stand-point it travels in a straight line.
I think I know what you're trying to say, but I understand it to be the other way around. Taking an accelerating earth, for example, the earth itself is a non-inertial frame as it is accelerating. From this non-inertial frame, the rock follows the parabola. From an inertial frame, say, another rock thrown straight up, the original rock appears to move straight horizontally. Also, from the original rock's inertial frame of reference, the earth is following a parabolic trajectory.
A non-intertial FoR is a FoR that is accelerating. The earth is not following a parabolic trajectory, its just that parallel lines can intersect.
-
The earth is not following a parabolic trajectory, its just that parallel lines can intersect.
If I jump down a couple steps off a porch, the earth appears to follow a parabolic arc, relative to my inertial frame of reference. To the non inertial FOR of the earth, I am the one following the parabola. Not sure where parallel lines are relevant. Also, if two lines intersect, they are by definition not parallel. Why would you suggest otherwise?
-
Not sure where parallel lines are relevant. Also, if two lines intersect, they are by definition not parallel. Why would you suggest otherwise?
Because space is non Euclidean. I think thats the piece of the puzzle you are missing and its key to understanding this. I'm about to go offline for a bit, but I'll talk about this more with you at a later time, if you'd like.
-
I think that limes are yellow because of a strange kind of sound that is produced only by the inverse kinematics of a former yesterday. As this with my logic, when scissors shut they are only purposed to cut whatever lay ahead and not any light or Tupperware. And it is for this reason that ;D is a trademark of Google, Inc. Anyone who has any comment on my basic theory of spider webs please insert ticket here.
-
When something falls, it goes in a straight line.
Or a parabola.
Nope, always a straight line unless acted upon by a real force.
If that is true and gravity doesn't count as a "real" force, then it must be concluded that the only way that objects can travel in "straight lines" that matches everyday experience, it must be concluded that space must be warping.
Correct.
Gravity isn't a real force in relativity. That has been the whole point of the last page of posts. Its a pseudoforce or ficticious force. And yes "space is warping" so to speak. Things travel their inertial path (a straight line).
I'm well aware of the difference between gravity and gravitation, but the fact remains, Einstein WAS NOT proposing that gravity doesn't exist, he was proposing that it is not a force.
This was Ski's quote that started this little sub-debate:On a round earth the person falling is still being pulled down by the mythical force of gravity. This would not account for the "normal" sensation.
In fact, Ski was trying to refute Markjo's invocation of the equivalence principle. As Ski himself says, a falling body is not subject to any forces; therefore the feeling of weightlessness that one feels while falling (after having reached terminal velocity) is not evidence of the earth rushing up to meet the "falling" person. The falling scenario is as Markjo stated, subject to the equivalence principle.
-
No. Markjo completely misapplied the equivalence principle to explain the scenario. The "falling sensation" has to do with contact force. It matters not whether the earth is round or flat in this scenario. The earth is accelerating upward, as is easily measured by an accelerometer. No measurable force is being applied to a falling-body. In either scenario it is more proper to say the earth is accelerating upward (or in a globe's case "outward"). In fact, it would best be described by saying that matter constantly expands and that local time is not linear but slows at a proportional rate.
Further, the idea of gravity pulling you down (his idea and words, not mine) is not relativistic gravitation nor universal acceleration, but Newtonian Gravity and the equivalence principle becomes meaningless. If being pulled down by Newtonian Gravity was "normal" as he stated, the sky diver would never notice a "falling sensation" because he would undergo continuous acceleration (which we know is not true, b/c we can measure it's absence with an accelerometer-- or in this case one's bowels).
-
No. Markjo completely misapplied the equivalence principle to explain the scenario. The "falling sensation" has to do with contact force. It matters not whether the earth is round or flat in this scenario. The earth is accelerating upward, as is easily measured by an accelerometer. No measurable force is being applied to a falling-body. In either scenario it is more proper to say the earth is accelerating upward (or in a globe's case "outward"). In fact, it would best be described by saying that matter constantly expands and that local time is not linear but slows at a proportional rate.
Further, the idea of gravity pulling you down (his idea and words, not mine) is not relativistic gravitation nor universal acceleration, but Newtonian Gravity and the equivalence principle becomes meaningless. If being pulled down by Newtonian Gravity was "normal" as he stated, the sky diver would never notice a "falling sensation" because he would undergo continuous acceleration (which we know is not true, b/c we can measure it's absence with an accelerometer-- or in this case one's bowels).
Relativistic Gravitation refers to the attraction of two bodies to eachother. Indeed the earth IS being pulled towards the jumper, but at a far less rate than the jumper is being pulled towards the earth. Now whether you call it 'pulled' or 'attracted' is purely semantics. Whether you call it up or down is purely semantics. Newtonian Gravity isn't anything different to relativistic gravitation; it is simply a less complete explanation of gravitation. Similiarly Relativistic Gravitation will be found to be a less complete explanation of gravitation when the Quantum model is completed.
Let's put it this way. If you were in a rocketship accelerating at say 9.8m/s/s, standing on a chair placed on a floor perpendicular to the travel of the rocket, you would feel a force equivalent to gravity, though it would infact be a fictitious force (as is gravity). If the chair was to be suddenly removed you would "gravitate" towards the floor of the rocketship and in the process, you would have a temporary feeling of weightlessness (akin to when a lift drops from under you). This is because for that moment, no force is acting upon you. You have ceased accelerating and any residual forward motion is due to your inertia and is at a constant (not accelerating) volocity. Eventually the ship catches up with you and you start accelerating again.
Now if you don't agree with this please explain where I am wrong?
-
I think that limes are yellow ...
Limes are green.
-
When something falls, it goes in a straight line.
Or a parabola.
Nope, always a straight line unless acted upon by a real force.
If that is true and gravity doesn't count as a "real" force, then it must be concluded that the only way that objects can travel in "straight lines" that matches everyday experience, it must be concluded that space must be warping.
Correct.
Gravity isn't a real force in relativity. That has been the whole point of the last page of posts. Its a pseudoforce or ficticious force. And yes "space is warping" so to speak. Things travel their inertial path (a straight line).
I'm well aware of the difference between gravity and gravitation, but the fact remains, Einstein WAS NOT proposing that gravity doesn't exist, he was proposing that it is not a force.
Yes, which would make it a ficticious or pseudoforce. It only exists from taking a noninertial FoR as a inertial FoR
This was Ski's quote that started this little sub-debate:On a round earth the person falling is still being pulled down by the mythical force of gravity. This would not account for the "normal" sensation.
I see nothing wrong with that statement. The word mythical is accurate. The force itself is non-existent within relativity. Its a pseudoforce or ficticious force. This is opposed to an actual force.
In fact, Ski was trying to refute Markjo's invocation of the equivalence principle. As Ski himself says, a falling body is not subject to any forces; therefore the feeling of weightlessness that one feels while falling (after having reached terminal velocity) is not evidence of the earth rushing up to meet the "falling" person. The falling scenario is as Markjo stated, subject to the equivalence principle.
Yes, ski is also correct here.
eta:
The feeling of being accelerated upwards is "normal". The absence of this acceleration is the feeling you describe.
Thanks to the equivalence principle, we can just as readily say that the feeling of being pulled down by gravity is "normal".
No, markjo. Thanks to the equivalence principle, we can just as readily say that the earth is accelerating us upwards on either a flat or round earth.
On a round earth the person falling is still being pulled down by the mythical force of gravity. This would not account for the "normal" sensation.
At first glance this seems fine. He has said that a re or a flat earth would have the same experience in this case due to the e.p.
No. Markjo completely misapplied the equivalence principle to explain the scenario. The "falling sensation" has to do with contact force. It matters not whether the earth is round or flat in this scenario. The earth is accelerating upward, as is easily measured by an accelerometer. No measurable force is being applied to a falling-body. In either scenario it is more proper to say the earth is accelerating upward (or in a globe's case "outward"). In fact, it would best be described by saying that matter constantly expands and that local time is not linear but slows at a proportional rate.
Further, the idea of gravity pulling you down (his idea and words, not mine) is not relativistic gravitation nor universal acceleration, but Newtonian Gravity and the equivalence principle becomes meaningless. If being pulled down by Newtonian Gravity was "normal" as he stated, the sky diver would never notice a "falling sensation" because he would undergo continuous acceleration (which we know is not true, b/c we can measure it's absence with an accelerometer-- or in this case one's bowels).
Relativistic Gravitation refers to the attraction of two bodies to eachother.
Relativistic gravition has nothing to do with the attraction of two bodies. It has to do with two bodies travelling straight lines.
If he is saying that on the flat earth you would have the "normal" feeling but on the RE you would not he is incorrect. He does not seem to be saying this however.
The earth accelerating you upwards is what you feel on ground. Think of the elevator thought experiment. On the elevator you feel a pull downwards while accelerated upwards. When in the air, this feeling is gone as you are no longer being accelerated upwards but in an inertial FoR. The pull downwards is the normal feeling caused by being accelerated upwards.
-
I think that limes are yellow because of a strange kind of sound that is produced only by the inverse kinematics of a former yesterday. As this with my logic, when scissors shut they are only purposed to cut whatever lay ahead and not any light or Tupperware. And it is for this reason that ;D is a trademark of Google, Inc. Anyone who has any comment on my basic theory of spider webs please insert ticket here.
Stop it you guys.
-
No. Markjo completely misapplied the equivalence principle to explain the scenario. The "falling sensation" has to do with contact force. It matters not whether the earth is round or flat in this scenario.
??? When did I say anything about the shape of the earth. Remember that the Davis FE model does use gravity. All I said is that the EP (when properly applied) makes it impossible to feel the difference between gravity and acceleration. Therefore, free fall will feel exactly the same regardless of whether the FE earth is rushing up to meet you or if the gravity of the FE is pulling you down.
-
I had a feeling you two were agreeing and everyone else was just trying to make a stink of it through misunderstanding heh.
-
If he is saying that on the flat earth you would have the "normal" feeling but on the RE you would not he is incorrect. He does not seem to be saying this however.
He attempted to use this point to discredit Markjo's invocation of the equivalence principle.
-
Because Markjo was attempting Newtonian force of gravity with equivalence. It cannot work that way.
-
When did I invoke Newton? ???
-
The earth is accelerating upward, as is easily measured by an accelerometer. No measurable force is being applied to a falling-body. In either scenario it is more proper to say the earth is accelerating upward (or in a globe's case "outward").
If being pulled down by Newtonian Gravity was "normal" as he stated, the sky diver would never notice a "falling sensation" because he would undergo continuous acceleration (which we know is not true, b/c we can measure it's absence with an accelerometer-- or in this case one's bowels).
Why do you continue to argue about things you do not understand? If you think you understand it, take a physics class and prove to yourself and others that you aren't just in denial about your misunderstandings of physical phenomena.
-
In RE you have invisible puller particles, in FE you have invisible pusher particles. Both sound equally odd.
Why does whatever is pushing the earth need to be invisible? Pusher particles don't sound odd. Puller particles sound odd. How can a particle pull?
But since gravity matches observations better than UA, we are brought to the conclusion that the Earth is in fact round.
Gravity doesn't match observations. No one has seen gravity. But everyone can see the upwards movement of the earth.
Except the rate at which things fall on earth is not consistent, so "everyone can see the upwards movement of the earth" doesnt really fit observations either. In fact it really destroys the idea of an upwards moving earth. For example things in certain parts of canada weigh less, even with equal masses.
http://www.newscientist.com/article/dn11826-satellites-solve-mystery-of-low-gravity-over-canada.html
-
So there is still no answer as to how this is possible in the FE model, because well, its not possible?
Except the rate at which things fall on earth is not consistent, so "everyone can see the upwards movement of the earth" doesnt really fit observations either. In fact it really destroys the idea of an upwards moving earth. For example things in certain parts of canada weigh less, even with equal masses.
http://www.newscientist.com/article/dn11826-satellites-solve-mystery-of-low-gravity-over-canada.html
-
Apparently the heavens have a gravitational pull which causes gravitational differences on the Earth's surface.
NOW gravitation is ok, but not on Earth. Definitely not something absurd like that...
-
One thing that FE'ers never consider is that while we do measure an upward force, that does not mean that the Earth is accelerating upward. What is being measured isn't the pull of gravity, its the acceleration due to the normal force of the ground.
For example, if you lean against a wall you feel a force pushing you back (otherwise you'd fall through the wall :P ). The existence of a force, and an acceleration, doesn't mean that the wall is moving, it is simply a results of Newtonian physics.
-
The differences due to location of gravitational pull are due to local mass.
-
The differences due to location of gravitational pull are due to local mass.
Exactly, that's what RE'ers have been saying for years ;D
-
The differences due to location of gravitational pull are due to local mass.
:o
VVV
-
The differences due to location of gravitational pull are due to local mass.
I think you just gave up the cause.
-
John hasn't given up anything. His Flat Earth can have gravity.
-
The differences due to location of gravitational pull are due to local mass.
Thank you john, but i already new why it made sense in your theory, unfortunately there is a significant portion of the FE community that denies that mass is the cause of gravitation on earth. That question was directed at them, sorry for the confusion.
-
Anyone have any clue why things in Canada weigh less in the UA model?
-
Anyone have any clue why things in Canada weigh less in the UA model?
Apparently celestial gravity causes such things.
-
And yet... no matter where the celestial bodies are in their orbit, or what time of the day, these anomalies do not move. Strange that while the heavens are in flux their influence is stationary.