Significance of Gravitational force


by paras02
Tags: force, gravitational, significance
paras02
paras02 is offline
#1
Nov10-12, 02:30 AM
P: 27
Hello friends !
I got confused in the point that how can a body exert a gravitational force on other body without coming in its physical contact ? Also please explain its mechanism or significance of gravitational force ?
Phys.Org News Partner Physics news on Phys.org
Physicists design quantum switches which can be activated by single photons
'Dressed' laser aimed at clouds may be key to inducing rain, lightning
Higher-order nonlinear optical processes observed using the SACLA X-ray free-electron laser
tiny-tim
tiny-tim is offline
#2
Nov10-12, 10:48 AM
Sci Advisor
HW Helper
Thanks
tiny-tim's Avatar
P: 26,167
hello paras02! welcome to pf!

in newtonian physics: same way an electric charge can exert a force on another charge without contact by a field

in einsteinian physics: there is no force, there is only the "warped" geometry of space-time
paras02
paras02 is offline
#3
Nov11-12, 03:59 AM
P: 27
Sorry I am unable to understand the answer given by you. Kindly clarify the question in more simple words.

ImaLooser
ImaLooser is offline
#4
Nov11-12, 04:02 AM
P: 571

Significance of Gravitational force


Quote Quote by paras02 View Post
Sorry I am unable to understand the answer given by you. Kindly clarify the question in more simple words.
The simplest answer is "we don't know." We don't know why. What physicists have are equations that enables them/us to predict what matter will do.
paras02
paras02 is offline
#5
Nov11-12, 04:10 AM
P: 27
you may be corect but I am still not satisfied
Vanadium 50
Vanadium 50 is offline
#6
Nov11-12, 05:14 AM
Mentor
Vanadium 50's Avatar
P: 15,608
OK, so you're not satisfied. Sorry about that.
mfb
mfb is online now
#7
Nov11-12, 09:24 AM
Mentor
P: 10,816
Physics is not about "why", it describes "how". Sometimes, the level of "how" is so deep that it looks like a reason, but it is just a more fundamental description how.
"Why" is something for philosophy.
grzz
grzz is offline
#8
Nov11-12, 09:42 AM
P: 939
Faraday pictured a way how to visualise 'action at a distance' by using the idea of a 'field'.
paras02
paras02 is offline
#9
Nov15-12, 01:29 AM
P: 27
sorry ! but science is based on proofs not on facts
harrylin
harrylin is offline
#10
Nov15-12, 04:50 AM
P: 3,178
Quote Quote by paras02 View Post
[..] how can a body exert a gravitational force on other body without coming in its physical contact ? Also please explain its mechanism or significance of gravitational force ?
Quote Quote by tiny-tim View Post
[..] in newtonian physics: same way an electric charge can exert a force on another charge without contact … by a field

in einsteinian physics: there is no force, there is only the "warped" geometry of space-time
That is in fact Einsteinian mathematics. Just as in Newtonian physics, in Einsteinian physics the effect is described with a gravitational field. That implies that something physical exists in vacuum that mediates the effect. However, we still don't know much about its "mechanism" (perhaps something for the Quantum forum?).

As this is the classical forum, do you want to know "classical" explanations such as by Newton?
Drakkith
Drakkith is online now
#11
Nov15-12, 05:02 AM
PF Gold
Drakkith's Avatar
P: 11,044
Quote Quote by paras02 View Post
sorry ! but science is based on proofs not on facts
No, the only proofs that exist are mathematical proofs. I like wikipedia's definition of a fact:

A fact (derived from the Latin factum, see below) is something that has really occurred or is actually the case. The usual test for a statement of fact is verifiability, that is whether it can be proven to correspond to experience. Standard reference works are often used to check facts. Scientific facts are verified by repeatable experiments.

Science is based on empirical evidence being gathered and explained using models, which are themselves based on scientific theories. A scientific theory is:

"a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment."[1][2] Scientists create scientific theories from hypotheses that have been corroborated through the scientific method, then gather evidence to test their accuracy. As with all forms of scientific knowledge, scientific theories are inductive in nature and do not make apodictic propositions; instead, they aim for predictive and explanatory force.

For example we explain gravity in classical physics as a force, where the magnitude of the force is based on a mathematical formula. This has been verified as being accurate to a very high degree, and only General Relativity is able to predict things more accurately, which is why it is now considered the modern theory of gravity. The fact that gravity acts at a distance, while surprising to many, is nothing special. ALL forces act through a distance. Nothing ever actually "touches" anything else the way you imagine it when you get down to the very small scale of atoms and molecules. Atoms and molecules themselves are not even solid objects. (In the normal everyday sense of "solid" that most people think of)
ImaLooser
ImaLooser is offline
#12
Nov15-12, 09:52 PM
P: 571
Quote Quote by paras02 View Post
sorry ! but science is based on proofs not on facts
Science is based on facts. Mathematical relations that have been proved under certain assumptions may be used. But scientists can't prove that those assumptions are correct.

So natural science can never really prove anything. It's pragmatic: things are used because they work, or not used because they don't work.
Nstraw
Nstraw is offline
#13
Nov16-12, 03:24 AM
P: 27
Quote Quote by Drakkith View Post
No, the only proofs that exist are mathematical proofs. I like wikipedia's definition of a fact:

A fact (derived from the Latin factum, see below) is something that has really occurred or is actually the case. The usual test for a statement of fact is verifiability, that is whether it can be proven to correspond to experience. Standard reference works are often used to check facts. Scientific facts are verified by repeatable experiments.

Science is based on empirical evidence being gathered and explained using models, which are themselves based on scientific theories. A scientific theory is:

"a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment."[1][2] Scientists create scientific theories from hypotheses that have been corroborated through the scientific method, then gather evidence to test their accuracy. As with all forms of scientific knowledge, scientific theories are inductive in nature and do not make apodictic propositions; instead, they aim for predictive and explanatory force.

For example we explain gravity in classical physics as a force, where the magnitude of the force is based on a mathematical formula. This has been verified as being accurate to a very high degree, and only General Relativity is able to predict things more accurately, which is why it is now considered the modern theory of gravity. The fact that gravity acts at a distance, while surprising to many, is nothing special. ALL forces act through a distance. Nothing ever actually "touches" anything else the way you imagine it when you get down to the very small scale of atoms and molecules. Atoms and molecules themselves are not even solid objects. (In the normal everyday sense of "solid" that most people think of)
i agree
paras02
paras02 is offline
#14
Nov16-12, 09:36 AM
P: 27
Thank you guys


Register to reply

Related Discussions
What is the difference between Gravitational acceleration and gravitational force? Introductory Physics Homework 1
Dot product of Force and Position as a constant of motion - physical significance? Calculus & Beyond Homework 2
How does light bend under gravitational field(gravitational force), why? Special & General Relativity 2
Free body diagram involving normal force, gravitational force, and applied force. Introductory Physics Homework 4
Gravitational Force, the derivative of Gravitational Potential Energy? Classical Physics 3