Theory of Gravity

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Theory of Gravity

#1  Postby Sonoran Lion » Jul 23, 2011 6:15 am

I am having a hard time finding information on whether or not a theory called the "theory of gravity" ever existed. I do know that gravity is explained using the theory of relativity currently. But before the theory of relativity, was there another theory of gravity? I think a misunderstanding I am having is that Newton's findings are referred to as Newton's Laws of Universal Gravitation. Thanks for any help. I ask this because someone I was having a discussion with believes a theory of gravity never existed, only laws of gravity.
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Re: Theory of Gravity

#2  Postby z8000783 » Jul 23, 2011 10:05 am

Laws only provides information about how the world works under certain conditions and does not seek to provide an explanation.

Newtons theory of Gravity posited that 2 masses will attract each other with a force proportional to the product of the masses and inversely proportional to the square of the distance between, however no such force has been found to exist.

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Re: Theory of Gravity

#3  Postby rEvolutionist » Jul 23, 2011 10:11 am

It's only a theory... :coffee:
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Re: Theory of Gravity

#4  Postby Animavore » Jul 23, 2011 10:23 am

Newton's Theory of Gravitation.

Let me guess. He's asking how come Darwin's theory is only a theory and why we never hear about the "law of evolution"?

EDIT: On the Wiki section called Newton's Law of Universal Gravitation there is a sub-section called Problems with Newton's theory.
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Re: Theory of Gravity

#5  Postby Sonoran Lion » Jul 23, 2011 3:53 pm

z8000783 wrote:Laws only provides information about how the world works under certain conditions and does not seek to provide an explanation.

Newtons theory of Gravity posited that 2 masses will attract each other with a force proportional to the product of the masses and inversely proportional to the square of the distance between, however no such force has been found to exist.

John


I do believe that Newton's theory of Gravity was the theory in place up to Einstein's theory of relativity.


rEvolutionist wrote:It's only a theory... :coffee:


And according to the person I am discussing with, a theory is only a hypothesis... :roll:


Animavore wrote:Newton's Theory of Gravitation.

Let me guess. He's asking how come Darwin's theory is only a theory and why we never hear about the "law of evolution"?

EDIT: On the Wiki section called Newton's Law of Universal Gravitation there is a sub-section called Problems with Newton's theory.


Thanks for the links. I am a little confused, is Newton's theory of gravity also referred to as Newton's law of universal gravitation?

That is pretty much his argument. He confuses the term theory as it is used in science with the colloquial use of the term - he calls a theory a hypothesis.
"I would rather be a could-be if I cannot be an are,
Because a could-be is a maybe that is reaching for a star.
I would rather be a has-been than a might-have-been, by far,
For a might-have-been has never been, but a has was once an are".
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Re: Theory of Gravity

#6  Postby j.mills » Jul 29, 2011 8:34 pm

All the major frameworks in science are known as 'theories': the theory of electromagnetism, the theory of plate tectonics, the theory of thermodynamics. Your chum's problem is, as you say, merely semantic, a perhaps wilful misunderstanding. Are these theories definitively proven? No: they are as proven as it is possible for them to be on the current evidence. Unless your chum has significant evidence unavailable to the scientific community, and is sufficiently familiar with the theory in question to assess the merits and importance of said evidence, he has no basis on which to assert that the theory is wrong. If he does have such a basis, the world's scientists will be delighted to read his peer-reviewed paper as soon as possible...
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Re: Theory of Gravity

#7  Postby rEvolutionist » Jul 30, 2011 12:18 am

It's just a theory.
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Re: Theory of Gravity

#8  Postby Sonoran Lion » Aug 04, 2011 5:10 am

j.mills wrote:All the major frameworks in science are known as 'theories': the theory of electromagnetism, the theory of plate tectonics, the theory of thermodynamics. Your chum's problem is, as you say, merely semantic, a perhaps wilful misunderstanding. Are these theories definitively proven? No: they are as proven as it is possible for them to be on the current evidence. Unless your chum has significant evidence unavailable to the scientific community, and is sufficiently familiar with the theory in question to assess the merits and importance of said evidence, he has no basis on which to assert that the theory is wrong. If he does have such a basis, the world's scientists will be delighted to read his peer-reviewed paper as soon as possible...


I agree that his problem seems to be one of semantics, but he also asserts that there is no theory of gravity, only laws of gravity (He refers to Newton's laws of universal gravitation as evidence). When I told him that I believed he was mistaken about there not being a theory of gravity, he accused me of saying that gravity was only a hypothesis (based on his misunderstanding of what a scientific theory is, which I had to correct him on a couple of times). The discussion was a little frustrating as physics is not my field of study (thus I was not as confident in my knowledge).
"I would rather be a could-be if I cannot be an are,
Because a could-be is a maybe that is reaching for a star.
I would rather be a has-been than a might-have-been, by far,
For a might-have-been has never been, but a has was once an are".
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Re: Theory of Gravity

#9  Postby trubble76 » Aug 04, 2011 9:47 am

Intelligent Falling Theory is gaining ground. You can't prove that a god isn't holding stuff down.
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Re: Theory of Gravity

#10  Postby rEvolutionist » Aug 04, 2011 10:18 am

trubble76 wrote:Intelligent Falling Theory...


:rofl:
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Re: Theory of Gravity

#11  Postby hackenslash » Aug 04, 2011 3:36 pm

Sonoran Lion wrote:I am having a hard time finding information on whether or not a theory called the "theory of gravity" ever existed. I do know that gravity is explained using the theory of relativity currently. But before the theory of relativity, was there another theory of gravity? I think a misunderstanding I am having is that Newton's findings are referred to as Newton's Laws of Universal Gravitation. Thanks for any help. I ask this because someone I was having a discussion with believes a theory of gravity never existed, only laws of gravity.


As others have pointed out, this is a semantic issue, but it's actually that the theory of gravitation and the law gravitation are two different things. A theory is a framework dealing with a class of facts of specific interest. A law is a mathematical description of a behaviour.

So, Newton's theory of Gravitation (which did not explain what gravity was; he left that to others) was the framework dealing with all observations, both extant and predicted, pertaining to the operation of gravity, while Newton's Law of Universal Gravitation is the equation that shows the relationships between two bodies mutually attracted under gravity, namely this one:

Image

Which can be expressed in plain language as 'every point mass in the universe attracts every other point mass with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.' (yoinked from wiki)
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Re: Theory of Gravity

#12  Postby Sonoran Lion » Aug 05, 2011 9:12 pm

trubble76 wrote:Intelligent Falling Theory is gaining ground. You can't prove that a god isn't holding stuff down.


And we must teach the controversy.


hackenslash wrote:
Sonoran Lion wrote:I am having a hard time finding information on whether or not a theory called the "theory of gravity" ever existed. I do know that gravity is explained using the theory of relativity currently. But before the theory of relativity, was there another theory of gravity? I think a misunderstanding I am having is that Newton's findings are referred to as Newton's Laws of Universal Gravitation. Thanks for any help. I ask this because someone I was having a discussion with believes a theory of gravity never existed, only laws of gravity.


As others have pointed out, this is a semantic issue, but it's actually that the theory of gravitation and the law gravitation are two different things. A theory is a framework dealing with a class of facts of specific interest. A law is a mathematical description of a behaviour.

So, Newton's theory of Gravitation (which did not explain what gravity was; he left that to others) was the framework dealing with all observations, both extant and predicted, pertaining to the operation of gravity, while Newton's Law of Universal Gravitation is the equation that shows the relationships between two bodies mutually attracted under gravity, namely this one:

Image

Which can be expressed in plain language as 'every point mass in the universe attracts every other point mass with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.' (yoinked from wiki)


Thanks, that betters my understanding of the issue.
"I would rather be a could-be if I cannot be an are,
Because a could-be is a maybe that is reaching for a star.
I would rather be a has-been than a might-have-been, by far,
For a might-have-been has never been, but a has was once an are".
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Re: Theory of Gravity

#13  Postby klazmon » Aug 06, 2011 4:14 am

In the case of Newton's law of of gravity, there are several unwritten assumptions which had to be brought front and center with general relativity. The first is that the system can be described in terms of Euclidean geometry. Second that time proceeds at all points in the Euclidean space in a uniform and absolute manner. Third that Galilean relativity applies. Fourth that the term (inertial) mass in Newton's second law (F = ma) has anything at all to do with the terms m1 and m2 (gravitational mass) in the law of gravitation. The theory is that all these assumptions and laws (mathematical equations) form an accurate description of objects interacting via the phenomena called gravity. We now know that the first three are wrong and the fourth (equivalence principle) remains under intense scrutiny.
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Re: Theory of Gravity

#14  Postby Animavore » Aug 06, 2011 8:09 am

I know there's no law of evolution, as creationists are wont to point out, but surely there must be laws of nature you could point to which govern evolution?
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Re: Theory of Gravity

#15  Postby hackenslash » Aug 06, 2011 9:16 am

Well, there are plenty of statistical laws that apply to population dynamics, drift, etc. susu.exp has presented quite a lot of information regarding this.
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Re: Theory of Gravity

#16  Postby Animavore » Aug 06, 2011 9:19 am

I suppose the laws of thermodynamics also. Actually I remember an article on RDF about cheetahs and thermodynamics.
EDIT: Here it is http://richarddawkins.net/articles/2973 ... modynamics
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