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Clarification on Gravity

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markjo

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Re: Clarification on Gravity
« Reply #990 on: February 16, 2009, 03:27:28 PM »
Quote from: bowler on February 16, 2009, 03:12:11 PM
Its not pedantic, its just different. Its not the physics version of going through checking everyones grammar its randomly redefining what a verb and what a noun is.

Quote from: markjo on February 16, 2009, 03:06:33 PM
Quote from: bowler on February 16, 2009, 02:26:12 PM
Why are the definitions of gravity and gravitation different on this website? Presumably the definitions changing is just going confuse people who know what they are and make learning harder for those who don't as it will not make sense if they try to read physics text books.

Because they like to be pedantic jerks and harass the noobs (not that most of the noobs don't deserve it). 

Actually, it's more like a running gag.
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Lord Wilmore

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Re: Clarification on Gravity
« Reply #991 on: February 17, 2009, 04:16:56 AM »
It is a bit of a running gag, but the point is that whilst in some cases it is just a derail tactic, in a lot of instances it is important to make the distinction. In the real world, you never need to distinguish between gravity and gravitation. On FES, you need to quite often, and as such, it's important to maintain the distinction in all discussions. Once you let it slip, and people start using them interchangably, nobody will know what you mean by which term.
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markjo

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Re: Clarification on Gravity
« Reply #992 on: February 17, 2009, 11:02:36 AM »
To be honest, I'm not sure that I've ever run into a discussion on FES where the distinction was that important.  Then again, I don't have a phd in physics either.  I suppose that I've figured that scientists use the terms interchangeably and pick up on what they actually mean by the context in which they were used.
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zork

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Re: Clarification on Gravity
« Reply #993 on: February 22, 2009, 04:44:47 AM »
Quote from: TheEngineer
This thread is about the difference between gravity and gravitation.
Topic name is Gravity and first post states - Since it's such a hot topic around here, I decided to just make a thread with this information regarding gravity and gravitation.
 There isn't anything about thread being "difference between gravity and gravitation". Although I agree that the first post describes terms gravity and gravitation in context of this forum but... if there is people who work with physics and they can argue about use of these terms then it's also appropriate to do here I guess.
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Rowbotham had bad eyesight
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http://thulescientific.com/Lynch%20Curvature%202008.pdf - Visually discerning the curvature of the Earth
http://thulescientific.com/TurbulentShipWakes_Lynch_AO_2005.pdf - Turbulent ship wakes:further evidence that the Earth is round.
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TheEngineer

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Re: Clarification on Gravity
« Reply #994 on: February 22, 2009, 07:47:48 AM »
Which is why I am here.   :-\
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zork

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Re: Clarification on Gravity
« Reply #995 on: February 22, 2009, 08:33:58 AM »
Quote from: TheEngineer on February 22, 2009, 07:47:48 AM
Which is why I am here.   :-\
Yes, I know that you are here to nitpick, harass newbies and to do incomprehensible statements. Like the one you just made.
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Rowbotham had bad eyesight
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http://thulescientific.com/Lynch%20Curvature%202008.pdf - Visually discerning the curvature of the Earth
http://thulescientific.com/TurbulentShipWakes_Lynch_AO_2005.pdf - Turbulent ship wakes:further evidence that the Earth is round.
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bowler

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Re: Clarification on Gravity
« Reply #996 on: February 23, 2009, 02:45:42 AM »
My argument was not over the of correct terminology but why after years of physics and checking with books the definition used here seems to be unique. I fail to understand how that is in anyway useful. If just confuses people who do know what they are talking about and makes it hard for others to research what they read here.
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TheEngineer

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Re: Clarification on Gravity
« Reply #997 on: February 23, 2009, 11:16:23 AM »
But there is your problem.  Most RE'ers don't know what they are talking about.  Most people are unaware that gravity specifically refers to the force that Newton theorized to exist between all objects with mass and gravitation refers to the apparent attraction between objects. 
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bowler

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Re: Clarification on Gravity
« Reply #998 on: February 23, 2009, 12:40:55 PM »
Noooooooooooooooooooooooooooooo.
Gravitation - Is the apparent attraction between 2 bodies due to their mass distribution. Since Newton this has been known about, since Einstein a mechanism has been offered. Possibly the most poorly understood force at a fundamental level.

Gravity - Is the effect on Earth due to the Earths mass distribution as well as its movement.

The usage in the first post is not consistent much less the rest of it. As markjo said its not apparent to me why the definition here is so important. Though if people are going to be so pedantic they can at least get it right. I don't think gravity is well understood here, myself included, I have not done postgraduate level GR so I cannot prove a lot of the statements made here or at least not without substantial effort. Though that doesn't bother me because no one else has so far.
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Jack

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Re: Clarification on Gravity
« Reply #999 on: February 23, 2009, 05:37:29 PM »
Quote from: bowler on February 23, 2009, 12:40:55 PM
Noooooooooooooooooooooooooooooo.
What are you blabbing about?

Quote from: bowler on February 23, 2009, 12:40:55 PM
Gravitation - Is the apparent attraction between 2 bodies due to their mass distribution. Since Newton this has been known about, since Einstein a mechanism has been offered. Possibly the most poorly understood force at a fundamental level.
Gravitation is not a force. Get your facts straight.

Quote from: bowler on February 23, 2009, 12:40:55 PM
Gravity - Is the fictitious force on Earth due to the Earths mass distribution as well as its movement.
Fixed.

Quote from: bowler on February 23, 2009, 12:40:55 PM
The usage in the first post is not consistent much less the rest of it. As markjo said its not apparent to me why the definition here is so important. Though if people are going to be so pedantic they can at least get it right. I don't think gravity is well understood here, myself included, I have not done postgraduate level GR so I cannot prove a lot of the statements made here or at least not without substantial effort. Though that doesn't bother me because no one else has so far.
In science, the distinction is very important. What's the point of developing the word "gravitation" when there is already the word "gravity?

Hint: Shh....they are different...
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bowler

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Re: Clarification on Gravity
« Reply #1000 on: February 24, 2009, 02:41:47 AM »
Right I have been over and over about the interpretation of gravity as a fictitious force and how life is not that simple. For my definition of gravitation and gravity I have posted 4 books by a selection of the best theorists of the last 100 years and THE book on classical mechanics. Yet the preferred definition still comes from the first thread which is not even consistent with itself, the mind boggles.

Thanks for telling me whats important in science the last decade of my life has really just been a complete waste of my time.
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TheEngineer

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Re: Clarification on Gravity
« Reply #1001 on: February 24, 2009, 05:59:26 AM »
I would love for you to tell me why it is not consistent.
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Omnomnom

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Re: Clarification on Gravity
« Reply #1002 on: February 26, 2009, 09:55:45 AM »
SO you people understand what this means ?

http://csep10.phys.utk.edu/astr161/lect/history/newtongrav.html
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TheEngineer

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Re: Clarification on Gravity
« Reply #1003 on: February 26, 2009, 10:31:26 AM »
I understand that it is wrong, yes.
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svenanders

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Re: Clarification on Gravity
« Reply #1004 on: February 26, 2009, 10:35:14 AM »
Quote from: TheEngineer on February 26, 2009, 10:31:26 AM
I understand that it is wrong, yes.

What is wrong with it? Enlighten us all!  :-*
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TheEngineer

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Re: Clarification on Gravity
« Reply #1005 on: February 26, 2009, 10:41:40 AM »
Quote from: divito the truthist on January 18, 2008, 02:08:57 PM

From TheEngineer:
 
"Gravity specifically refers to the force that Newton theorized happens between bodies with mass and is transmitted instantaneously.  This, however, is incorrect, for a few reasons.  One, gravity is not a force.  It only looks to us as one because we assume we are not accelerating, but are at rest.  However, we are undergoing a constant physical acceleration when we are in contact with the Earth, directly or otherwise.  Two, it only acts on objects with mass.  This leaves out a whole bunch of phenomenon.  Third, it violates the speed limit of the universe, the speed of light.
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Gizzard

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Re: Clarification on Gravity
« Reply #1006 on: February 26, 2009, 10:42:44 AM »
While it may indeed be wrong, does that change the fact that this is the best way of describing what we can observe with our own two eyes? You plug the numbers in and, wow! You get a number that agrees completely with what just happened!

Correct or not, it's a damn good approximation.

You're assuming we're accelerating. If you assume we're not accelerating (which in our reference frame does not make a difference) and this wierd phenomenon is, in fact gravity - then the same set of equations can be used to describe something which otherwise you cannot explain. Why would a massive object such as the earth not give rise to this observation, yet gravity can be observed between any other two objects you care to look at?
« Last Edit: February 26, 2009, 10:48:26 AM by Gizzard »
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svenanders

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Re: Clarification on Gravity
« Reply #1007 on: February 26, 2009, 10:46:35 AM »
Quote from: TheEngineer on February 26, 2009, 10:41:40 AM
Quote from: divito the truthist on January 18, 2008, 02:08:57 PM

From TheEngineer:
 
"Gravity specifically refers to the force that Newton theorized happens between bodies with mass and is transmitted instantaneously.  This, however, is incorrect, for a few reasons.  One, gravity is not a force.  It only looks to us as one because we assume we are not accelerating, but are at rest.  However, we are undergoing a constant physical acceleration when we are in contact with the Earth, directly or otherwise.  Two, it only acts on objects with mass.  This leaves out a whole bunch of phenomenon.  Third, it violates the speed limit of the universe, the speed of light.

So this is true just because you say so?
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TheEngineer

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Re: Clarification on Gravity
« Reply #1008 on: February 26, 2009, 10:54:15 AM »
Quote from: svenanders on February 26, 2009, 10:46:35 AM
So this is true just because you say so?
No, it is true because Einstein said so.
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Gizzard

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Re: Clarification on Gravity
« Reply #1009 on: February 26, 2009, 10:56:47 AM »
As I said before, find a better way of describing what can be observed by anybody then...
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TheEngineer

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Re: Clarification on Gravity
« Reply #1010 on: February 26, 2009, 11:00:43 AM »
Quote from: Gizzard on February 26, 2009, 10:42:44 AM
While it may indeed be wrong, does that change the fact that this is the best way of describing what we can observe with our own two eyes? You plug the numbers in and, wow! You get a number that agrees completely with what just happened!
You only get those answers because the equations were 'fudged' to make the numbers work.

Quote
If you assume we're not accelerating
Then you get a fictitious force.  In this context, gravity.
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Gizzard

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Re: Clarification on Gravity
« Reply #1011 on: February 26, 2009, 11:02:56 AM »
Do they, or do they not agree with experimental data?
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TheEngineer

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Re: Clarification on Gravity
« Reply #1012 on: February 26, 2009, 11:04:02 AM »
Quote from: TheEngineer on February 26, 2009, 11:00:43 AM
You only get those answers because the equations were 'fudged' to make the numbers work.
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Gizzard

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Re: Clarification on Gravity
« Reply #1013 on: February 26, 2009, 11:07:03 AM »
My point still stands. That's actually how science works - you observe something, you collect data, then you attempt to find a theory which accurately describes what has been observed.

You don't assume something to be true until it has been tested - thus there is evidence to support the point that has been made. Call it what you want, it works.

By your logic, all of physics is fudged. People have observed something happening, then thrown together a bunch of equations to make it look like they know what's going on - so you're using the same fudged arguments, making your argument no more valid than mine. With the obvious difference that mine agrees with what can be observed.
« Last Edit: February 26, 2009, 11:09:45 AM by Gizzard »
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TheEngineer

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Re: Clarification on Gravity
« Reply #1014 on: February 26, 2009, 11:09:45 AM »
My point still stands.  The equations only work because they were forced to work, by the addition of a completely made up factor.
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Gizzard

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Re: Clarification on Gravity
« Reply #1015 on: February 26, 2009, 11:14:08 AM »
That's because of the units, not because of the science.
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TheEngineer

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Re: Clarification on Gravity
« Reply #1016 on: February 26, 2009, 11:20:06 AM »
So you admit that the equation does not work on its own?  It needs a made up factor.
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Gizzard

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Re: Clarification on Gravity
« Reply #1017 on: February 26, 2009, 11:25:33 AM »
Yep.

As I said, this is due to the units. You could create different units, and the equation would still work. The 'made up factor' does not make something less valid. Especially when it can be determined experimentally by anyone, anywhere.

Saying that using a constant is 'fudging the equation' does not make the equation less valid. Take E=mc^2. Oh wait, that's not a valid equation either because Einstein fudged it with a constant.
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TheEngineer

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Re: Clarification on Gravity
« Reply #1018 on: February 26, 2009, 11:32:06 AM »
Now try using using Newton's equation to find the 'force' on something without mass.
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markjo

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Re: Clarification on Gravity
« Reply #1019 on: February 26, 2009, 11:32:22 AM »
I have kind of a silly question.  People keeps saying that Newton was wrong because he believed that gravity worked instantly, as opposed to Einstein who said that gravitation works at the speed of light.  So where in Newton's Laws of Gravitation does it say that gravity works instantly?  Is that claim documented in any of his laws on gravitation, or is it just a belief that he held because he didn't know any better?  Also, would Newton have been aware of massless particles?
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Science is what happens when preconception meets verification.
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Besides, perhaps FET is a conspiracy too.
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It is just the way it is, you understanding it doesn't concern me.
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