Sir motion of a matter can be explain completely from the curvature of space and time. But that dosen't sound that gravitational field and forces are fictitious because curvature in space-time is itself gravitational field . Greater the curvature higher the gravitational field and itself force also.

Derek,

It is funny that you asked!

Isn't any field, including a QF, is a numeric 'fiction' very useful for calculational purposes.

Do you believe that numbers and equations are 'real'?

Why single out the gravitational field, if the *main* underlying physical concepts are various fields?

There is a hot topic going on ,whether our description of universe through mathematics is a inherent property of nature or we do so for our convenience ....what are natural constants such as plank constant, planks length,etc...Are they inherent property of nature it self? These are really tough to answer.....

Now Come to ur question:

Ans

No gravity can't be fictitious, because it does has energy associated with them, whether we put heavier object on space time fabric or not, and also it penetrate through all 11 dimensions and hence losses its strength....But Now the question is what is Mass (of course it leads to higgs field which gives a mass to the particle...)..So it is not easy to declare gravity as something fictitious....

you better take a look on the book "Fabric of space time" written by Brain green...to understand what is gravity.....

Lev, This article demonstrates how purely numerical computation actually improves upon existing physical apparati:

http://news.harvard.edu/gazette/story/2013/08/seeing-depth-through-a-single-lens/?utm_source=SilverpopMailing&utm_medium=email&utm_campaign=08.07.daily%2520%281%29

That abstract geometric dimensional coordinates can be used to accurately describe the very real physical effects of gravitation indicates that the dynamical effects that determine those coordinates directly correspond to whatever physically produces those effects. The abstract, geometric 'curvature' (perhaps more correctly, radial contraction or focused dialation) of dimensional spacetime coordinates must directly relate to some still undescribed physical property of the spacetime medium.

That gravitational effects can be, varyingly, well described by either the spacetime field equations or inverse-square point-force equations indicates that, despite their practical usefulness, at least one of the two models cannot properly represent the actual physical interactions that produce gravitational effects.

Dear Derek,

thanks for your question, which is really the essence of all discussions around the geometrical understanding of gravitational interaction.

In modern physics ALL fundamental forces (strong, weak, electromagnetic) are explained by the exchange of virtual and real bosons (integer spin particles) between fermions (half-integer spin particles – matter). As Richard Feynman emphasized in his book devoted to field approach to gravitation (Richard Phillips Feynman, Fernando B. Morinigo, William G. Wagner, Brian Hatfield, "Feynman Lectures on Gravitation (Frontiers in Physics)" , 2002 | ISBN: 0813340381 | 232 pages ) “the geometrical approach is not necessary for gravity physics.”

Field gravity approach is based on Lagrangian formalism of the modern relativistic quantum theory and describe gravitational potential as the second rank symmetric tensor field in Minkowski space-time, which guaranty the conservation of the energy-momentum tensor of the gravitational field (which is absent in general relativity). Intriguingly .all classic relativistic gravity effects, which really tested by experiments/observations has the same values in both geometrical and field approaches. Moreover there are several crucial experiments which can distinguish between these approaches. For detailed discussion of such possibilities see

the book http://link.springer.com/book/10.1007/978-94-007-2379-5/page/1

and papers http://arxiv.org/abs/0809.2323 and http://arxiv.org/abs/0809.2328 .

So in the Field Gravity approach the gravitational field is the reality as all other physical fundamental interactions.

Dear Yurij,

"In modern physics ALL fundamental forces (strong, weak, electromagnetic) are explained by the exchange of virtual and real bosons (integer spin particles) between fermions (half-integer spin particles – matter)."

While the fundamental interactions of _matter_ are explained through the exchange of force carrying boson particles among particles of matter, such is not the case for gravitation. While a geometric approach may ultimately not be necessary to describe gravitational interactions, there is no evidence for an exchange of force carrying particles mediating an attractive interaction among material objects of mass.

Gravitation seems to be much different than the strong, weak and electromagnetic interactions of matter. This suggests that an interaction between an object of mass and its external vacuum is fundamental to gravity. In fact, the existence of an enveloping relative vacuum is necessary for the very existence of discrete material objects of mass. Conversely, material force effects are produced by interactions among discrete particles of matter.

In the physics of general relativity and according to the general equivalence principle: anything creates gravitational field. This is because anything carries a non-zero energy-momentum tensor, which is the source of gravitational field. Therefore, and as is well known, mass creates a gravitational field. Space-time curvature is itself caused by gravity. There are actually two different parts of general relativity. They're often stated as:

Space-time tells matter how to move

Matter tells space-time how to curve

There is no contradiction between curvature of space-time, gravitational field and the explaining of the movement of matter in space-time.

General Relativity is our most elegant and by far the best-tested theory of how matter, gravitation and space-time work.

Dear James,

gravity theory is not a conversation about attraction between bodies but the physical theory which operates with experimentally tested concepts and initial principles. If field-theoretical approach can explain all relativistic gravity effects without geometry but using standard Lagrangian formalism, then it worth to be studied carefully and gravity become real physical interaction between particles but not a curvature of space-time without the concept of energy-momentum of gravity itself (which is the element of reality).

Established theories of gravitation do not describe any mechanism that physically produce its effects, they use only abstract methods to describe its effects. This is unlike quantum field theory, which does describe the physical mechanisms by which particle force interactions are produced. IMO, in this way the description of gravitation is incomplete.

However, it seems that only those interested in folding gravitation into QFT as strictly a material force have any motivation to describe the physical processes responsible for producing gravitation. As I mention previously, I suspect that gravitation is not strictly a force of matter like the strong, weak and EM particle interactions, and may not easily be fit within QFT...

As all in physics, it is all about conventional models that hold true until they proof to be wrong.

It is ALL fiction, but a fiction that helps us understanding HOW things happen.

The difficulties exist when we start discussing WHY things happen.

Gravitation and the falling apple example, explains that the apple will fall and describes how it falls, but it does not give any insight on why it falls.

Statements such the apple fell because of the gravity, are commonly accepted but essentially wrong.

Remember that t-shirt:

http://www.thinkgeek.com/product/65a4/

http://www.huffingtonpost.com/derek-abbott/is-mathematics-invented-o_b_3895622.html

Https://www.researchgate.net/publication/256838918

Article The Reasonable Ineffectiveness of Mathematics [Point of View]

Yurij Baryshev wrote: “Intriguingly .all classic relativistic gravity effects, which really tested by experiments/observations has the same values in both geometrical and field approaches.”

I’m late to this discussion, but it goes to the core of the difference between physics and mathematics. There is a fundamental physical difference between the behavior of a test particle in a box orbiting a large mass and that of a box being accelerated by a force. The one particle will float freely in the orbiting box, the other with press against the wall of the box being accelerated by a force. So although the motion of the two boxes may have the same values in a chosen coordinate system, it may be mathematically interesting, but it is physically meaningless.

Yurij’s subsequent proposition “If field-theoretical approach can explain all relativistic gravity effects without geometry but using standard Lagrangian formalism…” is, physically, already flawed, simply because mathematics alone cannot discriminate between “some” and “all.”

Dear Arnold,

your note that “mathematics alone cannot discriminate” field gravity Feynman’s approach from Einstein’s geometrical description of gravity is absolutely correct.

There are direct physical experiments which will demonstrate (in near future) is gravity a kind of physical matter in space-time (as all other physical interactions in physics) or non-material space-time itself (see details in http://arxiv.org/abs/0809.2328 ).

Yurij, I have a different prediction! It's as simple as this: Isolate a body undergoing free gravitation and there is no evidence of a force.

Dear Arnold,

before suggesting an experiment on gravitation you should read the professional literature on gravitational experiments and theories but not popular science papers about flying cosmonauts.

In the free fall (and satellite on an orbite) the force is evident – it is just the cause of the free fall!

Your suggestion: “Isolate a body undergoing free gravitation” is a nonsense, because in physics there are a lot of interactions which should be tested in different conditions. And what is more to measure a force one should use the inertial system of reference (but not accelerated one).

A real experiment which can test equivalence principle is the measure of gravitational acceleration of a rotating body even in the Earth lab like Bremen Tower. At the level of (v/c)^2, where v is the linear velocity of rotation, there is strict prediction for difference for differently rotating balls. See discussions of eq.26 in the above reference (arXiv:0809.2328) and possibility of its detection in the Lunar Laser Ranging experiments.

Thank you, but a scientific experiment seeks to isolate the phenomenon being tested from extraneous factors. When you say "the force is evident" in a free fall or orbit you're invoking an extraneous factor: your coordinate system. Let yourself fall or orbit in parallel with the body being "forced" and the force suddenly becomes UNevident.

What sort of force is dependent on a perspective from a different coordinate system?

You keep talking about the POSSIBILITY that experiments with demonstrate the validity of field gravity theories, as-if the possibility is already an ACTUALITY, as-if speculative interpretations are conclusive. There is a most significant difference, and a higher standard in science.

I won't presume to know what you've been reading or what you should read, but let's try to be more clear.