Human's sense of falling?

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.

Quote from: jraffield1 on October 22, 2011, 08:39:24 PM

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...

Quote from: jraffield1 on October 22, 2011, 08:14:24 PM

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.

Quote

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.

Quote from: jraffield1 on October 22, 2011, 08:39:24 PM

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?

Quote

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.

Quote from: jraffield1 on October 22, 2011, 09:06:55 PM

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?

Quote from: Tom Bishop on October 22, 2011, 08:30:29 PM

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.

Quote from: jraffield1 on October 22, 2011, 09:06:55 PM

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.

Quote from: Ski on October 22, 2011, 06:27:06 PM

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.

Quote from: Ski on October 22, 2011, 09:29:45 PM

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.

Quote from: pitdroidtech on October 23, 2011, 03:30:41 AM

Quote from: Ski on October 22, 2011, 09:29:45 PM

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'.