Question

What is gravity? if it is a force than how it works at quantum level and how it works? what is the mechanics behind this?

Answer 1

according to Newton gravity is an fundamental interaction or force which leads to the fall of object and according to Newton in universe every particle attract each other by a force which is called gravity.

according to einstein gravity and acceleration are same things. Einstein's general theory of relativity explains gravity as a distortion of space caused by the presence of matter or energy. A massive object generates agravitational field by warping the geometry of the surrounding spacetime. gravity is not an ordinary force, but rather a property ofspace-time geometry.
new evidence tells not only why the universe exploded outward during its birth, but also that gravity is made of quantum particles, called gravitons Gravity is a very important force. Every object in space exerts a gravitational pull on every other, and so gravityinfluences the paths taken by everything traveling through space. It is the glue that holds together entire galaxies. It keeps planets in orbit.

according to some scientists gravity is an illusion created by other forces of nature.

let's take an example of hydrogen atom and helium atom
the hydrogen atom and helium atom generate
a helically polarized electromagnetic radiation from polar regions that bombards
neighbouring atom drawing them towards
the source of radiation which is called gravity radiation then it causes
the nucleus of neighbouringatom to spin axially and at the same time the spin of electrons of both atoms. in turn of that neighbouring atom generates helically polarized electromagnetic radiation. both the atom spin axially in the same direction hence the the both atoms pulls in the same direction and the forces are additive.
this is theory is know as gravitoelectric coupling. this was discovered In 1992 by the Russian researcher Eugene Podkletnov claimed to have discovered, whilst experimenting withsuperconductors, that a fast rotating superconductor reduces the gravitational effect.Many studies have attempted to reproduce Podkletnov's experiment, always to negative results.

present of gravity: 2009 Verlinde showed that the laws of gravity may be derived by assuming a form of the holographic principle and the laws of thermodynamics.he tells  gravity is not a true fundamental force of nature , but instead is a consequence of the universe striving to maximize entropy.

In 2010 Erik Verlinde surprised the world with a completely new theory of gravity. According to Verlinde, gravity is not a fundamental force of nature but an emergent phenomenon
he said that gravity emerges from the changes of fundamental bits of information, stored in the very structure of spacetime.
According to Erik Verlinde, there is no need to add a mysterious dark matter particle to the theory. In a new paper, which appeared today on the ArXiv preprint server, Verlinde shows how his theory of gravity accurately predicts the velocities by which the stars rotate around the center of the Milky Way, as well as the motion of stars inside other galaxies. We have evidence that this new view of gravity actually agrees with the observations, says Verlinde. At large scales, it seems, gravity just doesn behave the way Einstein theory predicts
One of the ingredients in Verlinde theory is an adaptation of the holographic principle, introduced by his tutor Gerard Hooft Verlinde now shows that this idea is not quite correct—part of the information in our universe is contained in space itself.

there are many local theory of gravity.

some of other famous theory of gravity are following::
GAUSS'S law of gravity
Teleparllel gravity theory.

Entropic gravity, as proposed by Verlinde in his original article, reproduces Einstein field equations and, in a Newtonian approximation, a 1/r potential for gravitational forces.
Gravity is a physical phenomenon by which objects are attracted to each other.

Isaac Newton described gravity as a universal force that attracts every object that has mass. Albert Einstein thought gravity is a result of the curvature of spacetime
and Erik verlinde proved the gravity is an phenomenon. What will be the next theory closer to the truth? 


conclusion ::: Gravity, or gravitation, is a natural phenomenon by which all things withmass are brought toward one another including planets,stars and galaxies. Since energy and mass are equivalent, all forms ofenergy, including light, also cause gravitation and are under the influence of it. On Earth, gravity gives weight to physical objects and causes the ocean tides. The gravitational attraction of the original gaseous matter present in theUniverse caused it to begin coalescing, forming stars – and the stars to group together into galaxies – so gravity is responsible for many of the large scale structures in the Universe. Gravity has an infinite range although its effects become increasingly weaker on farther objects. Although gravity is such a constant presence in our lives, its origin is still a deep mystery.

Answer 2

it's the physics that explains how everything works: the best description we have of the nature of the particles that make up matter and the forces with which they interact. Quantum physics underlies how atoms work, and so why chemistry and biology work as they do.