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What is the Gravity?

Description of Gravity;
|| A few centuries B.C. the Greeks described the first realistic model of the universe. The Earth in the center of it, and a sphere in which the stars where fixed on, was somewhere on the outside realm. This notion explained why the stars appear in the same places each year. The sun and the moon were also moving in circles around the earth. However, there where objects in the sky that seem to wander around without any predictable type of motion; they named these objects planets, from the Greek word for wanderer. Aristotle and Plato put the planets perfectly circling the earth, and that all objects were falling onto the earth. Although this picture nowadays seems ridiculous, one must understand the context of these times: people thought that nature must be absolutely symmetric, perfect*. The only types of motion that are perfect were the straight line and the circle. Also, earth was considered the heaviest of all 4 natural elements (earth, water, fire, air). Therefore the Earth was placed in the center of the universe so that all objects will fall towards it in straight lines. The only objects that couldn't fall in straight lines, the planets and the stars, had to move in circles around the earth.
Copernicus was born in 1473 and was greatly interested in sky observations, becoming one of the most well known astronomers of his time. At the age of 41, he gave to his friends an anonymous manuscript in which he claimed that if instead of the earth, strictly as a mathematical convenience,  the sun was placed in the center of the universe, then Ptolemy's system of epicycles could be greatly simplified. Of course he was afraid of letting his idea out because he would face extreme consequences.
Tycho Brahe, Brahe did not embrace the Copernician view of the universe; he invented one of his own, by placing the earth again at the center of the universe. However the sun now circled the earth, and all the planets circled the sun.
Johannes Kepler , Kepler's theory along with Brahe's data made astronomy 100 times more accurate than ever before. All I want to point out is the fact that in order for a minor experimental fact to be fitted into theory, a huge reconsideration of our understanding of the world must be introduced. That was the first time it ever happened, but it has occurred numerous times since then in the history of science.
Galileo Galilei, introduced for the first time the very essence of physics: experiments should be done (like the ancient Greeks did) but they should be tested with the theory using mathematical language. He created inclined planes with different inclination and let balls to roll on them, measuring the time it takes to go down the slope. He quickly realized that no matter what the slope was, gentler or steeper, given twice the time a ball would travel four times the distance. At that point he made his first huge leap of imagination: that this must be true in the limiting case, even if the plane was completely vertical, so it must be true for free falling bodies too. He managed to work out the mathematics of his experiments and figured that it meant uniform acceleration. Then as a second giant leap on imagination, he thought of bodies falling in the vacuum, an idea unthinkable at that point, for nothing to exist by itself He broke free of the bonds of the Aristotelian thought and stated that the only reason that makes bodies fall at different speeds was the existence of air; if one were to do the experiments in the vacuum all bodies should fall in the same way.
Isaac Newton, he found the laws that explained the previous discoveries of Kepler and Galileo (the laws were actually suspected, but he was the one who proved this was the indeed case). His inverse square law explained the ellipses that the planets make as Kepler realized, and his F=ma law (where F he put the newly founded gravity) explained the motion of the objects on the earth that Galileo had discovered. Second, he generalized his theory: he realized that the same laws that apply here on earth must also apply to the movement of the celestial bodies, and this is how he managed to explain the tides: as an earthly effect of celestial bodies. He made in that way the first great unification, the first out of many that were destined to come: laws that could explain both earthly and celestial phenomena.
It took Albert Einstein up to 10 years to find an answer, He concluded then that mass and energy must affect the gravitational field. Secondly, he stated that the gravitational field is not actually a force as Newton had described, but instead a curvature in space. To put it in simple words, the bodies are affected by gravity not because of a force directly exerted on them but because space is curved and therefore they have to follow space's grid. The presence of mass or energy does not affect the bodies directly; it affects the space first, and then the bodies move in this curved space. Maybe it s difficult to understand but as an analogy we can say being in a sea (or pool) using your finger to create ripples on the water. The presence of your finger in the water creates these waves and alters the geometry of water, it's not flat anymore. If you look through the rippled water you'll see the bottom distorted.
 This idea, that space can be bended by mass, has breathtaking ramifications. Since mass curves space and then the objects just move on this space, there is no reason why for example light couldn't follow space's curvature. Indeed, one of Einstein's first ideas was that light should be able to bend too, when massive objects exist close to it.
After several experiments, experimental teams leaded by Sir Arthur Eddington set off to measure the light deflection at solar eclipse, at 1919. By that time Einstein had figured out the correct equations of his general relativity theory, and found the exact amount of bending. At the crucial day of the solar eclipse the two teams collected the data and then compared them to Einstein's theoretical predictions; the matching was superb for the accuracy they had at the time.
Einstein's theory of gravity has never been disproved until now (2004). Soon after its completion, the theory of quantum mechanics was developed; a description of the world in very small scales. However, general relativity seems to be incompatible with quantum mechanics and breaks down (theoretically). In most of the cases, gravity is so weak that in such small scales it is ignored. However in the interior of a black hole, the huge amount of mass is not negligible. Also, this is the case at the early stages of the universe: ultra-condensed matter, lots of mass suppressed into quantum distances. In these cases, a quantum treatment of gravity will be needed, although there is no way right now to test how exactly general relativity must be modified.
Nowadays, some physicists talk about the new role that the quantum information plays in gravity sets the scene for a dramatic unification of ideas in physics. Some time ago Erik Verlinde at the the University of Amsterdam put forward one such idea which has taken the world of physics by storm. Verlinde suggested that gravity is merely a manifestation of entropy in the Universe. His idea is based on the second law of thermodynamics that entropy always increases over time. It suggests that differences in entropy between parts of the Universe generate a force that redistributes matter in a way that maximizes entropy. This is the force we call gravity.
But perhaps the most powerful idea to emerge from Verlinde's approach is that gravity is essentially a phenomenon of information.
Today, this idea gets a useful boost from Jae-Weon Lee at Jungwon University in South Korea and a couple of scientist. They use the idea of quantum information to derive a theory of gravity and they do it taking a slightly different tack to Verlinde.
At the heart of their idea is the tricky question of what happens to information when it enters a black hole. Physicists have puzzled over this for decades with little consensus. But one thing they agree on is Landauer's principle, that erasing a bit of quantum information always increases the entropy of the Universe by a certain small amount and requires a specific amount of energy.Jae Weon assume that this erasure process must occur at the black hole horizon. And if so, spacetime must organize itself in a way that maximizes entropy at these horizons. In other words, it generates a gravity-like force.
It also relates gravity to quantum information for the first time. Over recent years many results in quantum mechanics have pointed to the increasingly important role that information appears to play in the Universe.
Some physicists are convinced that the properties of information do not come from the behavior of information carriers such as photons and electrons but the other way round. They think that information itself is the ghostly bedrock on which our universe is built.
Gravity has always been a fly in this ointment. But the growing realization that information plays a fundamental role here too, could open the way to the kind of unification between the quantum mechanics and relativity that physicists have dreamed of.
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*They preferred symmetrical universe many years ago. But Einstein preferred symmetrical universe about 100 years ago and of course it was one of the biggest mistake of Einstein that forced him unable to make unification theory. His love to symmetry closed his eyes to reality so it force him to make one another fancy parameter to make his universe symmetrical; time!
He just put parameter of time to his equations to make symmetrical explanation for universe. But in another group they bigot and radical viewpoint in quantic universe forced them not to understand universe exactly. They just didn’t like symmetrical diamond of Einstein and liked to make asymmetrical woody universe! While if you want to combine Quantum Mechanics with General Relativity it just needs to omit one parameter from GR and one opinion from QM.
Omit time from GR and omit materialism from QM (fundamental element of universe is not tiny ball called particle and not fancy string with 26Dimension!!!).
In this way you have one common, observable & real force; ElectroMagnetic.
That we observe it with different effect in different scale.
Quantic effects in small scale in quantum mechanics normal effect of electricity & etc in classical scale and one important effect in large scale that called gravity.
So there s no independent force named gravity it s just EM in large scale without time without Graviton.

-          To be continue…




1 comment:

Anonymous said...

The *-footprint does not read well. I think I understand it, but it isn't too clear.