Clarification on Gravity

A while ago I was asked why the first was was internally inconsistent and I forgot to reply. Now I have some time ill reply to that.

I have no issue with the 3 facts at the top.

I do not agree with the next 3 paragraphs while a definition is obviously arbitrary the definitions do not agree with the ones in general scientific usage.  Whenever I post these are the definitions that I will be using for gravity and gravitation as defined in Classical Mechanics (Goldstein, Poole & Safko, 2002). Not to mention every book I can find that defines it and wikipedia. The gravitational field is defined as the force felt due to the mass distribution of the Earth. Please, please, please note that this is NOT dependent on the mechanism. In Newtonian gravitation this is MODELED by F = GMm/r^2 in general relativity the field is caused by the Riemann curvature tensor. If this is true then Einsteins gravitation should approximate to Newtons gravitation in the classical limit. We can easily show that GR corresponds to Newtons description in the classical limit, firstly v << 1.
(Apologies for the next bit I have no idea how to do tensor algebra in this forum so if theres random sups and subs I failed at covariance an contra-variance.)
As the particle must be traveling slowly compared to the speed of light so T^mn / T⁰⁰ = T^mn/p << 1.
i.e. stresses are small relative to mass-energy
One finds the world lines in general relativity approach those for Newtonian mechanics if g₀₀ = -1 -2V
One then finds that Rⁿ_0n0 = d²V / dxⁿ dyⁿ
Again some messing around with G = 8piT gives R₀₀ = 4pi X p
Contracting with above gives R₀₀ = d²V / dxⁿ dyⁿ
so d²V / dxⁿ dyⁿ = 4pi * p.

So we see that Newtons equations are simply the classical limit of Einsteins equations - this is gravitation.
At this point we note that even in Newton's theory the Force is very much like a fictitious force.
F = ma - inertial acceleration
F = mg - gravitational acceleration
Its even easier to see than for Einsteins equations. To complicate matters further in GR a photon feels the effects of gravity despite being massless.

Now Gravity.
Then the Earths gravity field is the gravitational field from above with an added contribution from centripetal force w²r = 3.38cm/s² (apparently) for the RE theory. So in RE theory about 0.3% of the acceleration due to gravity is due to centripetal force the rest is due to the Earths mass distribution. I suppose in FE theory you would want to replace this with some linear acceleration.

My main issue with the quotes is the difference between 'is a fictitious force' and 'can be viewed as a fictitious force'. If the difference is not important to you then you are missing the entire point. In physics we often talk about the spherical cow. This is a reference to modelling. A cow is a very hard object to model so one may consider it a a sphere. Then some time later someone else will come along and add legs to refine the model, then someone will refine it further with a head. Einstein's refined gravitation from Newton, importantly he gave it mechanism, but it is not complete. To use my analogy we have something thats starting to look like a cow but we are not there yet.

edit - rather predictably, chewed up the superscripts and subscripts.

I'm going to be honest I didn't read the whole thread so this may have been explained and if it was I'm very sorry but you say that gravity breaks the universal speed limit: the speed of light, but so does the FE theory of constant acceleration because if the theory is correct then the Earth is going much faster than the speed of light by now. So both theories supposedly break the universal speed limit.

I'm going to be honest I didn't read the whole thread so this may have been explained and if it was I'm very sorry but you say that gravity breaks the universal speed limit: the speed of light, but so does the FE theory of constant acceleration because if the theory is correct then the Earth is going much faster than the speed of light by now. So both theories supposedly break the universal speed limit.

You're literally mixing things up. Gravity travels instantaneously across any distances. Special Relativity, however, prevents the Earth from ever traveling faster than the speed of light; it can accelerate forever and never reach c. Gravitation, as predicted by General Relativity, travels at c. Not gravity.

Quote from: Friend 001 on April 03, 2009, 08:49:17 PM

I'm going to be honest I didn't read the whole thread so this may have been explained and if it was I'm very sorry but you say that gravity breaks the universal speed limit: the speed of light, but so does the FE theory of constant acceleration because if the theory is correct then the Earth is going much faster than the speed of light by now. So both theories supposedly break the universal speed limit.

You're literally mixing things up. Gravity travels instantaneously across any distances. Special Relativity, however, prevents the Earth from ever traveling faster than the speed of light; it can accelerate forever and never reach c. Gravitation, as predicted by General Relativity, travels at c. Not gravity.

wait what? how does gravity travel instantaneously. I know gravitation travels at C, I thought gravity does to.

Quote from: Jack on April 04, 2009, 10:50:42 AM

Quote from: Friend 001 on April 03, 2009, 08:49:17 PM

I'm going to be honest I didn't read the whole thread so this may have been explained and if it was I'm very sorry but you say that gravity breaks the universal speed limit: the speed of light, but so does the FE theory of constant acceleration because if the theory is correct then the Earth is going much faster than the speed of light by now. So both theories supposedly break the universal speed limit.

You're literally mixing things up. Gravity travels instantaneously across any distances. Special Relativity, however, prevents the Earth from ever traveling faster than the speed of light; it can accelerate forever and never reach c. Gravitation, as predicted by General Relativity, travels at c. Not gravity.

wait what? how does gravity travel instantaneously. I know gravitation travels at C, I thought gravity does to.

He means gravity, as the force that doesn't exist, predicts action at a distance.  Newton himself was never satisfied with that but that's what his theory predicted.

You're literally mixing things up. Gravity travels instantaneously across any distances. Special Relativity, however, prevents the Earth from ever traveling faster than the speed of light; it can accelerate forever and never reach c. Gravitation, as predicted by General Relativity, travels at c. Not gravity.

Wow what a crock of sh*t. Don't try and confuse people with your lame gobbledegook.

The words gravity and gravitation are interchangeable. If there were a difference, it would be that gravity decribes the earth alone, whereas gravitation describes any matter.

They both indicate an attraction between masses (or energy). That's something FE'ers have a hard time recognising.

Wow what a crock of sh*t. Don't try and confuse people with your lame gobbledegook.

The words gravity and gravitation are interchangeable. If there were a difference, it would be that gravity decribes the earth alone, whereas gravitation describes any matter.

They both indicate an attraction between masses (or energy). That's something FE'ers have a hard time recognising.

Gravity and gravitation are not the same thing. It's pretty hilarious that you are stating they're the same thing in this very thread.

Gravity and gravitation are not the same thing. It's pretty hilarious that you are stating they're the same thing in this very thread.

It's pretty hilarious that you can insist that they're different. You lack a fundamental understanding of physics, which instead has been replaced by some kind of arbitrary syntax parser.

Your mum's pretty hilarious.

Your mum's pretty hilarious.

Pitching insults?

Nice.

Quote from: Jack on April 09, 2009, 01:48:40 PM

Gravity and gravitation are not the same thing. It's pretty hilarious that you are stating they're the same thing in this very thread.

It's pretty hilarious that you can insist that they're different. You lack a fundamental understanding of physics, which instead has been replaced by some kind of arbitrary syntax parser.

What's a syntax parser?

What's a syntax parser?

Jack, obviously 

I reckon this guy will make it to... oooh... 60 posts before he quits in disgust?

Quote from: WardoggKC130FE on April 09, 2009, 04:11:52 PM

What's a syntax parser?

Jack, obviously 

I reckon this guy will make it to... oooh... 60 posts before he quits in disgust?

He's no Sokoral thats for sure.

I have a question about FE, and maybe you all can help me out...

If this is true (that the earth is flat), then how do we explain the fact that drilling for oil hasn't broken the world up yet or caused us to be crushed to death?  Let's look at a few things that FE states-

1) Gravity is a false belief, and that we're actually being held in place by the earth's movement

2) The world is held up by a couple elephants and a tortoise

If this is true (which I believe it is), then why hasn't the world broken into little pieces, or why are we still alive?  The force of the "dark energy" made by Darth Vader would create pressure on the air around us, and subsequently force the air through the holes that were created by oil companies.  The force of the air going through the drilling holes would not only create a constant whistling sound, but exert force enough to cause decay at the weak points of the holes.  Since the earth keeps moving, the dark energy would keep raining its expounding force upon the air, which would go into the drilling sites with increasing force, widening the holes.  At this point, one of two things would happen...

1) The world cracks because of the structural weaknesses created, thus splintering our fair planet into a million tiny fragments.  Help me Obi-Wan Kenobi, you're our only hope!

2) If the world somehow does not break up, then we're all crushed to death.  The world would eventually move so fast that the pressure exerted by the air slamming into the surface of the earth would be so great that it would flatten anything and everything not suited to living in high pressure environments.

Also, why hasn't our extensive oil mongering accidently pierced one of the elephants holding us up?  My guess is that is where the turtle comes in.  He could be possibly spotting the drill tips for them, and coordinating how they move and where they stand.  Maybe he's kind of like a nurse, and puts band-aids on there backs when Exxon gets a little too aggresive.

So they're you have it.  Could someone please answer these questions for me?  That is, if you're all not too busy feeding the elephants.

I have a question about FE, and maybe you all can help me out...

If this is true (that the earth is flat), then how do we explain the fact that drilling for oil hasn't broken the world up yet or caused us to be crushed to death?  Let's look at a few things that FE states-

1) Gravity is a false belief, and that we're actually being held in place by the earth's movement

2) The world is held up by a couple elephants and a tortoise

If this is true (which I believe it is), then why hasn't the world broken into little pieces, or why are we still alive?  The force of the "dark energy" made by Darth Vader would create pressure on the air around us, and subsequently force the air through the holes that were created by oil companies.  The force of the air going through the drilling holes would not only create a constant whistling sound, but exert force enough to cause decay at the weak points of the holes.  Since the earth keeps moving, the dark energy would keep raining its expounding force upon the air, which would go into the drilling sites with increasing force, widening the holes.  At this point, one of two things would happen...

1) The world cracks because of the structural weaknesses created, thus splintering our fair planet into a million tiny fragments.  Help me Obi-Wan Kenobi, you're our only hope!

2) If the world somehow does not break up, then we're all crushed to death.  The world would eventually move so fast that the pressure exerted by the air slamming into the surface of the earth would be so great that it would flatten anything and everything not suited to living in high pressure environments.

Also, why hasn't our extensive oil mongering accidently pierced one of the elephants holding us up?  My guess is that is where the turtle comes in.  He could be possibly spotting the drill tips for them, and coordinating how they move and where they stand.  Maybe he's kind of like a nurse, and puts band-aids on there backs when Exxon gets a little too aggresive.

So they're you have it.  Could someone please answer these questions for me?  That is, if you're all not too busy feeding the elephants.

your retarted

No, its YOU'RE RETARDED.  Try and have better grammar, people have to read this.

No, its YOU'RE RETARDED.

That second word should be "it's". The apostrophe is necessary to indicate that it represents a contraction of the words "it is". Try and have better grammar, people have to read this. Oh wait, no they don't.

No, it's YOUR RETARTED. 

Fix'd.

No, its YOU'RE RETARDED.  Try and have better grammar, people have to read this.

lol fail

Are you one of the oter otters, or an entirely different variety of otter?

I can't help but notice you've all failed to answer any of those questions...

I can't help but notice you've all failed to answer any of those questions...

What questions? 

Quote from: AngryOtter83 on April 11, 2009, 05:46:03 PM

No, it's YOUR RETARTED. 

Fix'd.

QFT

its almost as though I never explained exactly what gravity was. 'Gravity travels instantaneously'!!!!!!! what manner of gibberish is that. The phrase I hate most of all 'gravity is not a force'. Seriously who ever coined the term fictitious force should be punished most severely. Force is an observer dependent quantity, the interaction is fundamental, force isn't. Im going to be honest sitting here right now it certainly seems like gravity is a force inertial or fundamental. ARGH, I don't even care what shape the world is why does this most simple of facts seem to confuse people.

its almost as though I never explained exactly what gravity was. 'Gravity travels instantaneously'!!!!!!! what manner of gibberish is that. The phrase I hate most of all 'gravity is not a force'. Seriously who ever coined the term fictitious force should be punished most severely. Force is an observer dependent quantity, the interaction is fundamental, force isn't. Im going to be honest sitting here right now it certainly seems like gravity is a force inertial or fundamental. ARGH, I don't even care what shape the world is why does this most simple of facts seem to confuse people.

It's been labelled a 'fictitious force' because you can transform into a frame where it does not exist (or at least is not locally measurable)... try doing that with the strong nuclear force.

Next time your in a car with someone who decides to accelerate rapidly try telling your sore neck that its a fictitious force. Inertial im fine with, fictitious seems to imply it isn't there. Thousands of people all over the world in car crashes beg to differ not to mention roller coaster enthusiasts. Its a philosophical point it has no effect on the physics but it winds me up none the less. Everybody seems fine with most other macroscopic quantities being observer dependent.

Both of the examples you gave are simply conservation of linear momentum, not gravity. The rollercoaster accelerates whether the Earth is accelerating upwards or whether you are assuming the Earth is a gravitating mass - the result is the same either way.

The force you feel pushing you back into your seat when a car accelerates is an inertial force. Infact its the example in just about every book on classical mechanics written since in the invention of the motor car.

Yes, that is correct. 

How does this relate to gravity being a force of nature in the same class as the strong, weak and electromagnetic forces again?

It doesn't but the electroweak and strong interactions are interactions. They transfer momentum which macroscopically appears as a force. The very idea of force at a quantum mechanical level is at best poorly defined. Force is a macroscopic quantity that describes the resistance of a body with inertial mass to acceleration. As such I would argue that the idea of a 'fundamental force' is a contradiction in terms which is why the term fundamental interaction is, in my opinion, more correct. I'm not presenting an argument for why gravity is a quantum field, I suspect it is, but all I can show is that QFT and GR are incomplete. My point is simply that the term fictitious force, is at best misleading. However not nearly as misleading as the idea the the quantum fields are in any way more or less fundamental than gravity. All other inertial forces occur out of viewing quantum interactions in various frames. I would argue that gravity must be in some way as fundamental regardless of whether the mechanism is quantum mechanical or not.

is it really that important if its called fictious or something else? if you're in the wrong (or right   ) FOR the effects are apparent and the fact that it is not existent in another FOR doesn't solve your problems.

that's something i dislike here: many noobs utter their thoughts not 100% physical correctly but in most cases its not hard to figure out what they wanted to say. we have a lot of intelligent people here and i know it's sometimes hard to draw the line between exactness and an understandable answer but many people here go for option one and that's imo not appropriate for the laymen. and that fictious force discussion is definately one of the very confusing things if you lack physics knowledge.

so, just a small rant, think about it and now you may go on with your discussion