The Equivalence Principle and all its fun

Quote from: TheEngineer on March 11, 2007, 08:31:45 AM

Why is that silly?  Relative to me, that's exactly what happened.  There is no preferred frame of reference in relativity. 

Yes, if you're purely using vision to observe the situation, you could say that the entire earth is moving underneath you.  You have your sense of touch, however, and with it you're able to feel the force on yourself, and confirm that you are the one accelerating.  It's as simple as that.

If I am accelerating, space must therefore warp around me in order for me to do so. 

If I was in the dead of space and there was another spaceship approaching me and we are at constant velocity, how am I to tell if I am moving or standing still?  Relativity guarantees that any frame that I choose to use will be correct and equivalent to every other frame.  Thus, the apparent paradoxes in the theory.

Quote from: The Philosopher on March 11, 2007, 11:12:17 AM

Quote from: TheEngineer on March 11, 2007, 08:31:45 AM

Why is that silly?  Relative to me, that's exactly what happened.  There is no preferred frame of reference in relativity. 

Yes, if you're purely using vision to observe the situation, you could say that the entire earth is moving underneath you.  You have your sense of touch, however, and with it you're able to feel the force on yourself, and confirm that you are the one accelerating.  It's as simple as that.

If I am accelerating, space must therefore warp around me in order for me to do so. 

If I was in the dead of space and there was another spaceship approaching me and we are at constant velocity, how am I to tell if I am moving or standing still?  Relativity guarantees that any frame that I choose to use will be correct and equivalent to every other frame.  Thus, the apparent paradoxes in the theory.

 
The twin paradox was solved.

If I am accelerating, space must therefore warp around me in order for me to do so. 

If I was in the dead of space and there was another spaceship approaching me and we are at constant velocity, how am I to tell if I am moving or standing still?  Relativity guarantees that any frame that I choose to use will be correct and equivalent to every other frame.  Thus, the apparent paradoxes in the theory.

You continue to ignore my main question.. what a surprise.

At constant velocity you wouldn't be feeling any force, thus you are right, you would be unable to distinguish whether you or another object was moving.  If you are in an accelerated reference frame and can feel a force on you, however, you can conclude that you yourself are accelerating.  If you can't feel a force, then you're not the one accelerating.  It's not complicated; it's called using your sense of touch.

Quote from: The Philosopher on March 11, 2007, 11:12:17 AM

Quote from: TheEngineer on March 11, 2007, 08:31:45 AM

Why is that silly?  Relative to me, that's exactly what happened.  There is no preferred frame of reference in relativity. 

Yes, if you're purely using vision to observe the situation, you could say that the entire earth is moving underneath you.  You have your sense of touch, however, and with it you're able to feel the force on yourself, and confirm that you are the one accelerating.  It's as simple as that.

If I am accelerating, space must therefore warp around me in order for me to do so. 

If I was in the dead of space and there was another spaceship approaching me and we are at constant velocity, how am I to tell if I am moving or standing still?  Relativity guarantees that any frame that I choose to use will be correct and equivalent to every other frame.  Thus, the apparent paradoxes in the theory.

That's an excellent example of where relativity makes great sense, and either scenario is just as possible.  However, I'm talking about here on Earth, where people would notice if the entire Earth accelerated for no apparent reason, and one lone car sitting on the road didn't accelerate with it.

Blind faith in science is just as bad as blind faith in anything else. Sometimes it's better to just use common sense. We know the car is accelerating past the school. The driver feels it and the pedestrians do not feel the acceleration. We know what the case is just like we know the earth is not a disk accelerating through space. We are not living in some theoretical scenario that must meet certain conditions.

The twin paradox was solved.

As I stated already.  Nice of you to keep up with the conversation.

At constant velocity you wouldn't be feeling any force, thus you are right, you would be unable to distinguish whether you or another object was moving.  If you are in an accelerated reference frame and can feel a force on you, however, you can conclude that you yourself are accelerating.  If you can't feel a force, then you're not the one accelerating.  It's not complicated; it's called using your sense of touch.

But what if I want to claim that I am not accelerating?

Quote from: The Philosopher on March 11, 2007, 04:52:29 PM

At constant velocity you wouldn't be feeling any force, thus you are right, you would be unable to distinguish whether you or another object was moving.  If you are in an accelerated reference frame and can feel a force on you, however, you can conclude that you yourself are accelerating.  If you can't feel a force, then you're not the one accelerating.  It's not complicated; it's called using your sense of touch.

But what if I want to claim that I am not accelerating?

Then what's causing the force you're experiencing?

The warpage of space.

The warpage of space.

So when you observe that someone else is accelerating with reference to you, they're warping space in a way that makes you feel a force?

No, because I can claim I am at rest.

You're contradicting yourself....

Lets make things a little clearer; take this situation:
You are accelerating in your car.  You say you can claim that the earth is moving around you.  However, you observe that you're being pressed back against your seat.  Since this could only happen with a force being applied to you (reactant force due to your acceleration), you can conclude that you're the one accelerating, not the earth around you.

Do you agree? If not, why (use legitimate examples and reasoning, and please don't answer with a single sentence that ignores my entire point)?

you can conclude that you're the one accelerating, not the earth around you.

I can also conclude that I am at rest.  I don't understand why this is so hard for you to understand.  Read a little into General and Special Relativity if you don't believe me.

I can also conclude that I am at rest.  I don't understand why this is so hard for you to understand.  Read a little into General and Special Relativity if you don't believe me.

Please explain how you're able to come to that conclusion, and don't just say it's because of the equivalence principle.  Tell me exactly what about the equivalence principle and special relativity can lead you to this conclusion.

Another way of stating the equivalence principle is that gravitational acceleration is indistinguishable from other forms of acceleration. According to this view a student in a closed room could not tell the difference between experiencing the gravitational pull of the earth at the earth's surface and being in a rocketship in space accelerating with a = 9.8 m/s2.

EXPERIENCING the two accelerations is indistinguishable.  This does not at all imply that if you see someone accelerating, you wouldn't be able to tell if it was that person or yourself who was actually accelerating.

Drawing equivalence between two frames of reference is only possible if:
1) One frame is experienced/perceived and you're equating that frame with another one that you could be experiencing/perceiving.
2) You're observing an external frame of reference, and you're equating that frame with another external frame of reference.

Please explain how you're able to come to that conclusion, and don't just say it's because of the equivalence principle.  Tell me exactly what about the equivalence principle and special relativity can lead you to this conclusion.

Special and General Relativity allow me to claim it.

EXPERIENCING the two accelerations is indistinguishable.  This does not at all imply that if you see someone accelerating, you wouldn't be able to tell if it was that person or yourself who was actually accelerating.

Drawing equivalence between two frames of reference is only possible if:
1) One frame is experienced/perceived and you're equating that frame with another one that you could be experiencing/perceiving.
2) You're observing an external frame of reference, and you're equating that frame with another external frame of reference.

You are missing the point of Relativity.  All reference frames are correct.

Special and General Relativity allow me to claim it.

Explain

You are missing the point of Relativity.  All reference frames are correct.

Explain.  And please give a real, specific explanation instead of your one sentence im-smarter-than-you-refer-to-this-to-learn-why answers.  I'd really like you to explain exactly what about special relativity/general relativity/the equivalence principle led you to your conclusion.  If you don't want to write it all out yourself, then at least post a few explanatory quotations and a link to the references.

General Relativity asserts that ALL reference frames, including rotating and accelerating ones, are equivalent.  It's not something that I am going to teach you.  I am not your teacher.  Go and research it for yourself.

General Relativity asserts that ALL reference frames, including rotating and accelerating ones, are equivalent.  It's not something that I am going to teach you.  I am not your teacher.  Go and research it for yourself.

I never disagreed with that.  I'm talking about the ways in which you can observe an accelerating reference frame, and what this tells you about that acceleration.  Your argument that you can say the earth is accelerating underneath you is easily refuted with the observation that you feel the reactant force pushing you against your seat.

Your argument that you can say the earth is accelerating underneath you is easily refuted with the observation that you feel the reactant force pushing you against your seat.

So you are telling me that, yours, is a preferred frame of reference?

Quote from: The Philosopher on March 12, 2007, 02:25:09 PM

Your argument that you can say the earth is accelerating underneath you is easily refuted with the observation that you feel the reactant force pushing you against your seat.

So you are telling me that, yours, is a preferred frame of reference?

I'm saying that the earth moving underneath you wouldn't cause you to be pressed back against your seat, thus proving that situation impossible.

haven't you climaxed yet Engineer?

I'm saying that the earth moving underneath you wouldn't cause you to be pressed back against your seat, thus proving that situation impossible.

I get it, you believe your FOR is preferred.  Well, that's fine, if that's what you want to believe.  I would suggest you write up a paper about how Einstein was wrong and there is a preferred FOR, therefore, Relativity is wrong.  You just might get a Nobel Prize if you can prove why.

I get it, you believe your FOR is preferred.  Well, that's fine, if that's what you want to believe.  I would suggest you write up a paper about how Einstein was wrong and there is a preferred FOR, therefore, Relativity is wrong.  You just might get a Nobel Prize if you can prove why.

I'm asking you to explain what the flaw in my logic is.  I'd appreciate a real answer instead of the same old bs over and over again.  I think Einstein would agree with me... the equivalence principle is usually used to predict third-person events.

How about a real answer instead of same condescending bullshit

I'm asking you to explain what the flaw in my logic is.

When you say your frame of reference is preferred over mine.

I think Einstein would agree with me.

Seeing as what you are saying is the exact opposite of what is stated in Relativity, I would venture so far as to say Einstein would not agree with you.

.. the equivalence principle is usually used to predict third-person events.

Then you don't know what it is.

How about a real answer instead of same condescending bullshit

I can only give you the same answer because it is correct and you refuse to accept it.  ALL FRAMES OF REFERENCE ARE EQUAL AND EQUIVALENT IN GENERAL RELATIVITY.  LOOK IT UP IF YOU DON'T BELIEVE ME.

Quote from: The Philosopher on March 12, 2007, 03:26:28 PM

I'm asking you to explain what the flaw in my logic is.

When you say your frame of reference is preferred over mine.

Quote

I think Einstein would agree with me.

Seeing as what you are saying is the exact opposite of what is stated in Relativity, I would venture so far as to say Einstein would not agree with you.

Quote

.. the equivalence principle is usually used to predict third-person events.

Then you don't know what it is.

Quote

How about a real answer instead of same condescending bullshit

I can only give you the same answer because it is correct and you refuse to accept it.  ALL FRAMES OF REFERENCE ARE EQUAL AND EQUIVALENT IN GENERAL RELATIVITY.  LOOK IT UP IF YOU DON'T BELIEVE ME.

What a surprise, the same answer again... Why don't you at least quote something that proves your example instead of telling me to learn about the equivalence principle... based on everything I've read about it, your example is invalid.

That or we can just take into account that there is no gravity, and in fact just a kind of magnetic force that pulls down the carbon atoms found in everything rather than saying acceleration or gravity even exist?  This is fact because this is my FAQ!  See?

CARBON MAGNETISM FAQ

READ THIS BEFORE POSTING!

Carbon - The most common atom found in every living/non-living thing.
Carbon Magnetism - FACT!

FAQs
1. What is Carbon?
   A.  Read the FAQ
2. What is Carbon Magnetism?
   A.  Read the FAQ
3. How is it true?
   A.  Because it's found on the internet and I say it is.
   = OR =
   A.  Read the FAQ

Hopefully this clears up any concerns you might have about gravity and that the acceleration theory is a complete CONSPIRACY the GOVERNMENT is BRAINWASHING us with!!!

Thanks for your time,
~ Clint

What a surprise, the same answer again... Why don't you at least quote something that proves your example instead of telling me to learn about the equivalence principle... based on everything I've read about it, your example is invalid.

I told you to read up on General Relativity.

The difference between general and special relativity is that in the general theory all frames of reference including spinning and accelerating frames are treated on an equal footing.  In special relativity accelerating frames are different from inertial frames.  Velocities are relative but acceleration is treated as absolute.  In general relativity all motion is relative.  To accommodate this change general relativity has to use curved space-time.  In special relativity space-time is always flat.

The general principle of relativity states that physical laws should be the same in all reference frames -- inertial or non-inertial.

Physics in non-inertial reference frames was historically treated by a coordinate transform, first, to an inertial reference frame, performing the necessary calculations therein, and using another coordinate transform to return to the non-inertial reference frame. In most such situations, the same laws of physics can be used if certain predictable fictitious forces are added into consideration; an example is a uniformly rotating reference frame, which can be treated as an inertial reference frame if one adds a fictitious centrifugal force and Coriolis force into consideration.

The problems involved are not always so trivial. Special relativity predicts that an observer in an inertial reference frame doesn't see objects they'd describe as moving faster than the speed of light. However, in the non-inertial reference frame of Earth, treating a spot on the Earth as a fixed point, the stars are observed to move in the sky, circling once about the Earth per day. Since the stars are light years away, this observation means that, in the non-inertial reference frame of the Earth, anybody who looks at the stars is seeing objects which appear, to them, to be moving faster than the speed of light.

Since non-inertial reference frames do not abide by the special principle of relativity, such situations are not self-contradictory. However, they do provide a strong motivation to look for a set of physical laws which are constant in all reference frames -- inertial or non-inertial.

One of the greatest sources of confusion about general relativity comes from the need to distinguish between coordinate and physical accelerations.

In classical mechanics, space is preferentially mapped with a Cartesian coordinate system. Inertial motion then occurs as one moves through this space at a consistent coordinate rate with respect to time. Any change in this rate of progression must be due to a force, and therefore a physical and coordinate acceleration were in classical mechanics one and the same. It is important to note that in special relativity that same kind of Cartesian coordinate system was used, with time being added as a fourth dimension and defined for an observer using the Einstein synchronization procedure. As a result, physical and coordinate acceleration correspond in special relativity too, although their magnitudes may vary.

In general relativity, the elegance of a flat spacetime and the ability to use a preferred coordinate system are lost (due to stress-energy curving spacetime and the principle of general covariance). Consequently, coordinate and physical accelerations become sundered. For example: Try using a radial coordinate system in classical mechanics. In this system, an inertially moving object which passes by (instead of through) the origin point is found to first be moving mostly inwards, then to be moving tangentially with respect to the origin, and finally to be moving outwards, yet is moving in a straight line. This is an example of an inertially moving object undergoing a coordinate acceleration, and the way this coordinate acceleration changes as the object travels is given by the geodesic equations for the manifold and coordinate system in use.

The Philosopher is just saying that there is a difference if it is you who is actually moving, because you would feel a force. For instance, my hair does not fly when I am just standing while my friend rides a bike.

But that's just because The Philosopher doesn't know what he's talking about.

But that's just because The Philosopher doesn't know what he's talking about.

Yes I do.  The equivalence principle is used for calculating, describing and predicting third-person physical events relativistically.  When it becomes a first person experience, however, you can use your 5 senses to gain a more specific understanding of the type of acceleration you're experiencing.  Hence, when you push down the gas pedal in your car and the earth seems to move undeneath you, your sense of touch - in the form of your being pressed back against your seat - leads you to the conclusion that you're the one accelerating, not the ground beneath you.

This experience of acceleration, however, would be indistinguishable from undergoing any other type of acceleration.  This is how the equivalence principle applies to this example.  All we're really arguing about at this point is that The Engineer used a faulty example... so just admit it already