In Quantum physics everything in the world is made of 12 quarks , Leptons and force particles. These exist in various combinations on a nano scale. It is the force particle that gives everything mass and weight. The CERN collider in Geneva, Switzerland the scientists think they have found a force particle called it Higgs particle. This is what they call the god particle. Gravity ebbs and flows according to the mass and energy of an object. Drop a ten pound ball from a prescribed height as it falls the ball is weightless from the effects of gravity until it hits a condensed mass with a stronger gravitational field.
While the actual weight of a person is determined by his mass and the acceleration of gravity, one's "perceived weight" or "effective weight" comes from the fact that he is supported by floor, chair, etc. If all support is removed suddenly and the person begins to fall freely, he feels suddenly "weightless" - so weightlessness refers to a state of being in free fall in which there is no perceived support. The state of weightlessness can be achieved in several ways, all of which involve significant physical principles.
The mass of an object is a fundamental property of the object; a numerical measure of its inertia; a fundamental measure of the amount of matter in the object. Definitions of mass often seem circular because it is such a fundamental quantity that it is hard to define in terms of something else. All mechanical qualities can be defined in terms of mass, length, and time. The usual symbol for mass is m and its SI unit is the kilogram. While the mass is normally considered to be an unchanging property of an object, at speeds approaching the speed of light one must consider the increase of its relativistic mass - as a mass approaches the speed of light, c, its mass becomes infinite.
The weight of an object is the force of gravity on the object and may be defined as the mass times the acceleration of gravity, w = mg. Since the weight is a force, its SI unit is the newton. Density is mass/volume.
Beyond Newton, Einstein said gravity is not a force but a consequence of a curvature of space-time which in turn should mean that it would act on all masses the same way. This insight is at the core of the theory of general relativity that Einstein himself described as “the most fortunate thought in my life”. Indeed.
That most fortunate thought has now been again proved right with unprecedented accuracy:
“An international research team including astronomers from the Max Planck Institute for Radio Astronomy in Bonn determined with extremely high precision that gravity causes neutron stars and white dwarf stars to fall with equal accelerations. They did this by precisely tracking the motion of pulsar PSR J0337+1715*, a neutron star that is a member of an unusual triple star system. Their findings – achieved by a new rigorous method and a combination of radio telescope data with latest insight from gravitational wave detectors – provide the strongest test ever of one of the most fundamental predictions of general relativity: that gravity attracts all objects with the same acceleration, without regard for their composition, density or the strength of their own gravitational field,” an official release from the Max Planck Institute for Radio Astronomy in Bonn said on June 20th of this year.
“Confirming it to this precision constitutes one of the most stringent tests of Einstein’s theory ever made - and the theory passes the test with flying colors”, the release quotes Guillaume Voisin, one of the team members, as saying. "Moreover, the results also provide very stringent constraints on alternative theories of gravity, which compete with Einstein's general relativity to explain gravity and, for example, dark energy.”
“The universality of free fall is a unique feature of gravity: Unlike all other interactions in nature, gravity attracts all material objects with the same acceleration. Galileo Galilei allegedly dropped several differently-sized weights from the leaning tower of Pisa to test this. Isaac Newton later considered this to be a fundamental principle of gravity, presenting it without a deeper explanation. The most precise test of the universality of free fall has, to date, been obtained by an especially designed satellite called Microscope (developed by the Centre Nationale d'Études Spatiales, in France). The small proof masses within the satellite show identical accelerations in the gravitational field of the Earth to better than 1 part in 10 raised to 14,” it says.
* PSR J0337+1715 is an unusual neutron star located about 4,200 light-years from Earth, spinning nearly 366 times per second. It was first observed by Jason Boyles of Western Kentucky University using the
NSF's Green Bank Telescope**.
This image shows the pulsar PSR J0337+1715. Image credit: Ransom SM et al.
Such rapidly-spinning pulsars are called millisecond pulsars, and can be used by astronomers as precision tools for studying a variety of phenomena, including searches for the elusive gravitational waves.
Subsequent observations showed that PSR J0337+1715 is in a close orbit with a white dwarf star, and that pair is in orbit with another, more-distant white dwarf star.
** The Green Bank Telescope, or GBT, is the world’s premiere single-dish radio telescope operating at meter to millimeter wavelengths. Its enormous 100-meter diameter collecting area, its unblocked aperture, and its excellent surface accuracy provide unprecedented sensitivity across the telescope’s full 0.1 – 116 GHz (3.0m – 2.6mm) operating range.
The single focal plane is ideal for rapid, wide-field imaging systems – cameras. Because the GBT has access to 85% of the celestial sphere, it serves as the wide-field imaging complement to ALMA and the EVLA. Its operation is highly efficient, and it is used for observations about 6500 hours every year, with 2000-3000 hours per year available to high frequency science.
Part of the scientific strength of the GBT is its flexibility and ease of use, allowing for rapid response to new scientific ideas. It is scheduled dynamically to match project needs to the available weather. The GBT is also readily reconfigured with new and experimental hardware, adopting the best technology for any scientific pursuit. Facilities of the Green Bank Observatory are also used for other scientific research, for many programs in education and public outreach, and for training students and teachers.