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Gravity: a repost

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Gravity: a repost
« on: October 08, 2007, 01:30:25 PM »
Although a good question, armyguy unfortunately used a poor example for proving the existence of gravity, and now the thread isn't even about gravity anymore. So please, in this thread please only post if you're talking about gravity.

Gravity has been proved and measured many times. The original Cavendish experiment to determine the coefficient of gravity can be read about here. The basis of the experiment is that a minute force between weights is measured through the twisting in a wire that the weights are suspended by.
Since then, these and more experiments have taken place (feel free to google if you don't trust that source). The numbers obtained for the gravitational constant shown in the last link are very precise; they are within fractions of a percent of each other. If gravity were nonexistent, multiple independent universities couldn't get constants that agree so closely.

So, FE'ers, how do you explain away these experiments that prove gravity?
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TheEngineer

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Re: Gravity: a repost
« Reply #1 on: October 08, 2007, 07:56:06 PM »
Gravity as a force does not exist.  What they are witnessing is gravitation.  Now, the FE does not deny the existence of gravitation, just universality of it.
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Re: Gravity: a repost
« Reply #2 on: October 19, 2007, 04:14:40 AM »
You FE'ers do realise that when we say "Gravity" we mean gravitation or whatever you call it. We refer to the attractive force between two masses.
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Re: Gravity: a repost
« Reply #3 on: October 19, 2007, 06:34:34 AM »
Ahh... I absolutely love Cavendish's experiment. Mainly because you wouldn't think such a thing could possibly work without some massive percentage errors.

But the FE model says that even though gravity may exist in all its aspects (which not all FE'ers believe, mind you), UA overrides much of its perceivable effects because the UA is so darned large in comparison.
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Re: Gravity: a repost
« Reply #4 on: October 19, 2007, 09:34:33 AM »
Quote from: Hturtfothgileht on October 19, 2007, 04:14:40 AM
You FE'ers do realise that when we say "Gravity" we mean gravitation or whatever you call it. We refer to the attractive force between two masses.
You RE'ers do realize that gravity and gravitation are not the same thing, right?  The words are not interchangeable.  In fact, one necessarily precludes the other.

Gravity as a force does not exist.
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Re: Gravity: a repost
« Reply #5 on: October 19, 2007, 11:25:54 AM »
Gravitation as a force does exist, and you do not deny that. I should have been more astute in my terminology, however what are the stars, sun and moon orbiting?
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Re: Gravity: a repost
« Reply #6 on: October 19, 2007, 12:12:50 PM »
Quote from: Hturtfothgileht on October 19, 2007, 11:25:54 AM
Gravitation as a force does exist, and you do not deny that. I should have been more astute in my terminology, however what are the stars, sun and moon orbiting?

Quote from: Tom Bishop
The sun and the moon are, in turn, orbiting the other
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Re: Gravity: a repost
« Reply #7 on: October 19, 2007, 01:03:35 PM »
Quote from: Hturtfothgileht on October 19, 2007, 11:25:54 AM
Gravitation as a force does exist
Gravitation is not a force.
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Re: Gravity: a repost
« Reply #8 on: October 19, 2007, 01:36:58 PM »
It is a force. You can say that gravity is not a force, because of the terminology, but you can't get away with that.

If the sun and moon orbit each other, then explain the perculiar spiral orbit of the sun. Also, in order for the sun and moon to orbit each other, they would have to travel around the orbit in the same direction and at the same speed, so solar/lunar eclipses are impossible.
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Re: Gravity: a repost
« Reply #9 on: October 19, 2007, 01:40:11 PM »
Quote from: Hturtfothgileht on October 19, 2007, 01:36:58 PM
It is a force.
Gravitation is not a force.  It is a consequence of space.

Quote
You can say that gravity is not a force, because of the terminology, but you can't get away with that.
Gravity is not a force, not due to terminology, but due to physics.
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Re: Gravity: a repost
« Reply #10 on: October 19, 2007, 01:43:38 PM »
Gravity is a curvature of space-time, as Einstein theorised. It is a force, it causes mass to accelerate, and F = ma.
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divito the truthist

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Re: Gravity: a repost
« Reply #11 on: October 19, 2007, 01:47:36 PM »
"In scientific terminology gravitation and gravity are distinct. "Gravitation" is the attractive influence that all objects exert on each other, while "gravity" specifically refers to a force which all massive objects (objects with mass) are theorized to exert on each other to cause gravitation. Although these terms are interchangeable in everyday use, in theories other than Newton's, gravitation is caused by factors other than gravity."

And if you need the sources for gravity not being a force, I can supply those too.
« Last Edit: October 19, 2007, 01:49:08 PM by divito the fascist »
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Re: Gravity: a repost
« Reply #12 on: October 19, 2007, 01:58:30 PM »
Well, what are these factors?
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Re: Gravity: a repost
« Reply #13 on: October 19, 2007, 01:59:12 PM »
Quote from: Hturtfothgileht on October 19, 2007, 01:43:38 PM
Gravity is a curvature of space-time, as Einstein theorised. It is a force, it causes mass to accelerate, and F = ma.
Gravity is a pseudo force that only arises by taking a non inertial frame of reference to be inertial.   Gravitation is a consequence of the deformation of space, no force between objects necessary.
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divito the truthist

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Re: Gravity: a repost
« Reply #14 on: October 19, 2007, 02:37:41 PM »
Quote from: Hturtfothgileht on October 19, 2007, 01:58:30 PM
Well, what are these factors?

Space-time curvature.
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Re: Gravity: a repost
« Reply #15 on: October 19, 2007, 02:40:52 PM »
Force (physics) is defined as: "the influence that produces a change in a physical quantity"

Such a quantity is velocity. Change in velocity is acceleration, gravity(or gravitation) causes acceleration so gravity(gravitation) is a force.
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TheEngineer

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Re: Gravity: a repost
« Reply #16 on: October 19, 2007, 02:51:58 PM »
Quote from: Hturtfothgileht on October 19, 2007, 02:40:52 PM
Force (physics) is defined as: "the influence that produces a change in a physical quantity"
So by your definition, centrifugal force is an actual force.
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Re: Gravity: a repost
« Reply #17 on: October 19, 2007, 02:57:37 PM »
Well, the clue would lie in the name, "Centrifugal Force."
It is the definition of force. Gravity obeys this definition, if the centrifugal force also does, then it too is a force.
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divito the truthist

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Re: Gravity: a repost
« Reply #18 on: October 19, 2007, 02:59:08 PM »
Even if the definition of force fits what gravity is to be thought as, it doesn't change that gravity is non-existent.
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Re: Gravity: a repost
« Reply #19 on: October 19, 2007, 02:59:50 PM »
Quote from: Hturtfothgileht on October 19, 2007, 02:57:37 PM
Gravity obeys this definition, if the centrifugal force also does, then it too is a force.
False, and false.  Both are pseudo forces that only arise in non inertial FoRs taken to be inertial.
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TheEngineer

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Re: Gravity: a repost
« Reply #20 on: October 19, 2007, 03:00:57 PM »
Quote from: Hturtfothgileht on October 19, 2007, 02:40:52 PM
Force (physics) is defined as: "the influence that produces a change in a physical quantity"

Such a quantity is velocity. Change in velocity is acceleration, gravity(or gravitation) causes acceleration so gravity(gravitation) is a force.
By the way, F=ma does not hold in non inertial frames of reference. 
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Re: Gravity: a repost
« Reply #21 on: October 19, 2007, 03:04:16 PM »
Doesn't matter whether it's a force or not, (it is), if it didn't exist then it's effects, i.e. orbits, would not work and so the sun should not have a circular path.

(Gravity is defined as "the force of attraction between all masses in the universe.")

So, if gravity does not exist, then the sun and moon can not orbit each other.
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Re: Gravity: a repost
« Reply #22 on: October 19, 2007, 03:17:41 PM »
Quote from: Hturtfothgileht on October 19, 2007, 03:04:16 PM
(Gravity is defined as "the force of attraction between all masses in the universe.")
So what about things without mass?
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Re: Gravity: a repost
« Reply #23 on: October 19, 2007, 03:20:17 PM »
That's just a simple one-line definition of gravity. It does effect photons and other non-mass objects, but they follow the curvature of space-time, so gravity does affect them.
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divito the truthist

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Re: Gravity: a repost
« Reply #24 on: October 19, 2007, 03:23:13 PM »
I'll have to keep gathering more sources, but here we go since this is in a gravity thread (items bolded for visibility):

Quote
"All fictitious forces are proportional to the mass of the object upon which they act, which is also true for gravity. This led Albert Einstein to wonder whether gravity was a fictitious force as well. He noted that a freefalling observer in a closed box would not be able to detect the force of gravity; hence, free falling reference frames are equivalent to an inertial reference frame (the equivalence principle). Following up on this insight, Einstein was able to show (after ~9 years of work) that gravity is indeed a fictitious force; the apparent acceleration is actually inertial motion in curved spacetime. This is the essential physics of Einstein's theory of general relativity." - http://en.wikipedia.org/wiki/Fictitious_force

Quote
"Is Gravity A Fictitious Force?

...

The strange and in some ways disturbing answer to this supposition is that the phenomenon of gravity (the fact that things fall, and have weight) is real, but the force of gravity, as described by Newton, is not a real force, but a fictitious force."
- http://cseligman.com/text/physics/fictitious.htm

Quote
"With general relativity, Einstein managed to blur forever the distinction between real and fictitious forces. General relativity is his theory of gravity, and gravity is certainly the paradigmatic example of a "real" force. The cornerstone of Einstein's theory, however, is the proposition that gravity is itself a fictitious force (or, rather, that it is indistinguishable from a fictitious force)." - http://www.sciam.com/askexpert_question.cfm?articleID=ABE57453-E7F2-99DF-32538FF7C7B37F20

Quote
"You have it essentially right

mdivito@cevo.com wrote:
> user_email -- mdivito@cevo.com
> question -- I was just looking for some clarification of a few things in regards to gravitation.
>
> GR basically showcases that gravity as a force doesn't exist, correct?
>
> Now, as I understand it, gravity only needs to exist as a force in Euclidean spacetime, and since GR states that spacetime is non-Euclidean, what we feel on Earth is therefore gravitation, and not gravity?
>
>
>
>   

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Quote
"This is analogous to what mass does to the structure of space-time. It causes a depression to form so that if an object  rolls toward it, it falls into the pit and is captured. (This, by the way, is how Einstein envisioned how gravity works. Mass distorts the space-time causing particles to roll toward the mass. Note that the objects follow the shape of the space-time and in this sense are following an unforced motion! That is, there is no gravitational force, objects are simply following their natural motions.)" - http://zebu.uoregon.edu/~imamura/122/lecture-2/gw.html
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Re: Gravity: a repost
« Reply #25 on: October 19, 2007, 03:35:13 PM »
So, gravity is not itself a force, but it acts like a force?
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Re: Gravity: a repost
« Reply #26 on: October 19, 2007, 04:44:53 PM »
Quote from: Hturtfothgileht on October 19, 2007, 03:35:13 PM
So, gravity is not itself a force, but it acts like a force?
ONLY WHEN LOOKED AT FROM A NON INERTIAL FoR THAT HAS BEEN TAKEN TO BE INERTIAL.
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TheEngineer

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Re: Gravity: a repost
« Reply #27 on: October 19, 2007, 06:01:42 PM »
Nope.
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Re: Gravity: a repost
« Reply #28 on: October 19, 2007, 06:09:13 PM »
Quote from: TheEngineer
You RE'ers do realize that gravity and gravitation are not the same thing, right?  The words are not interchangeable. Gravitation is not a force.  It is a consequence of space.

Odd, how gravity is constantly questioned by you and other FEers for what is "reaching out and grabbing objects" to attract them. Now you just state gravitation is a "consequence of space" without justification. How could gravity not be a consequence of space? Explain.

Btw...
Quote from: divito the fascist
"Although these terms are interchangeable in everyday use"...
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Re: Gravity: a repost
« Reply #29 on: October 19, 2007, 06:25:25 PM »
Quote from: L0gic on October 19, 2007, 06:09:13 PM
Now you just state gravitation is a "consequence of space" without justification.
Gravitation is a consequence of the deformation of space and our tendency to follow geodesics through spacetime.

Quote
How could gravity not be a consequence of space?
Because gravity specifically refers to a force, one which propagates instantaneously. 
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