The universe of Einstein

Physics has made in the 19th century progress and striking the community of physicists from the beginning of the 20th century, in a heated debate on the fundamental laws of the Universe.
On one side, supporters of a mechanical world obeying the laws of Newton and the other advocates a world based on electricity and magnetism.
At this time there is talk of ether present in all space, which spreads the electromagnetic and gravitational phenomena. Einstein's theory of relativity will return to this debate since 1905.
In 1665 a man was sitting under a tree when suddenly he saw an apple fall in front of him. With the fall of the apple Isaac Newton revolutionized the whole image of the universe. In a bold assumption for his time, he asserts that the force that pulls the apple to the ground is the same one that keeps the Moon around the Earth.

Suddenly he unifies heaven and Earth into a single theory he called 'gravity'.
Gravity was the first force that is scientifically understood but 3 other forces would eventually follow and what is that Newton discovered the law of gravitation, there are over 300 years, these equations describing this force are so accurate predictions that we continue to use today.
It is they who have allowed scientists to calculate the trajectory of a rocket that took man to the moon.

NB: In Greek "ether" is a philosophical concept whose function is to fill the space that can not be empty.

Image: Thanks to the seriousness that the sun has captured 99.86% of the total mass of dust and gas of the primordial nebula. Jupiter, the largest planet in the system, has captured 71% of the remaining mass. Other planets have shared the residue of the gravitational evolution, i.e. 0.038% of the total mass.

With Newton there was a problem, if its laws describe the force of gravity with great precision, yet Newton hides an embarrassing secret, he has no idea how gravity works.
Not until the early 20th century a small office employee of Swiss technical inventions will bring a new view of gravity. While studying patent applications, Albert Einstein meditates on the behavior of light, there is no idea that his reveri.e. on the light led him to solve the mystery of the nature of gravity.
At age 26, Einstein made a startling discovery. The speed of light is a kind of cosmic speed limit, a speed that nothing in the universe can not exceed.
The trouble is that if nothing can travel faster than light, it goes against the Newtonian view of gravity. If a cosmic catastrophe the sun suddenly disappeared completely, the effect on the planets according to Newton is immediate. His theory predicts that if destruction of the sun, the planets would rush out of their orbits to drift into space.
Newton envisioned gravity as a force acting instantaneously at any distance.

Immediately you would feel the effect of destroying the sun, but Einstein saw a huge problem in the theory of Newton. He knew that the light is propagated not instantaneously, it takes sunlight 8 minutes to travel 150 million miles that separates the Earth. But he has demonstrated that nothing, not even gravity can not travel faster than light, how the Earth would leave its orbit before the darkness resulting from the disappearance of the sun is reaching our eyes?
For the young scientist's Swiss office nothing can exceed the speed of light and thus the Newtonian view of gravity was wrong.
If Newton is wrong why the planets do not they fall? Newton sought to explain why the planets in orbit. But Newton's equations are used to calculate their trajectory.
Einstein had to resolve this dilemma. Einstein must imagine a picture of the universe in which gravity does not exceed the cosmic speed limit.
In a solitary quest to solve this mystery and after 10 years of reflection, Einstein finally found the answer in a new kind of unification.

Einstein finally consider 3 dimensions of space and the single dimension of time, as related in the same tissue of Spacetime. He hoped that this understanding of the geometry of this four-dimensional tissue of space-time would allow him to speak simply of objects moving along the surface of this Spacetime. As the surface of a trampoline, the tissue is united distended and distorted by heavy objects such as planets and stars and this distortion or curvature of Spacetime, which creates what it feels like gravity. A planet like Earth is now in orbit not because the Sun will check and instantly seizes as in Newton's theory, but simply because it follows the curves of the tissue space curve caused by the presence of sun. With this new understanding of gravity we know now that if the sun disappears, as in our cosmic catastrophe, the gravitational disturbance that results, will form a wave that propagates through the tissue space in the same way that ripples in the surface of the water when you throw a pebble into a pond. We therefore feel no change in our orbit around the sun until the wave reaches the Earth. Also Einstein calculated that gravity waves travel at exactly the speed of light. So with this new approach, Einstein resolved the conflict with Newton to know how fast gravity propagates.

Einstein will give the world a new image of what is really the force of gravity. These curves and distortions in the fabric of space and time. He calls this new picture of gravity, general relativity. Despite his extraordinary success the physicist is not yet satisfied and he immediately sets another goal even higher, the unification of gravity with the only other known force at the time electromagnetism. The unified electromagnetism had had a few decades ago by Scotsman James Clark Maxwell 4 through mathematical equations.
Einstein was convinced that if he can unify his new theory of gravity with Maxwell's electromagnetism, it will be able to make the famous master equation, one can describe the whole universe.
Einstein did not succeed, for already a group of young scientists in the 1920s, would describe a new theory, string theory, a new and very eccentric to think physics.