General relativity:
Phenomena that would stem from Einstein's theory
weirdest phenomena ..

1. The theory of relativity

Time Dilation, Length Contraction, E = m c², black holes, big bang, gravitational waves; all this words come from Relativity.

Albert Einstein, German and American physicist (1879 - 1955) duilt special relativity in 1905.

Henri Poicaré, French mathematician, theoretical physicist (1854 - 1912), and Hendrik Antoon Lorentz , well known by his transformation equations, a Dutch physicist (1853 - 1928) were the kwnown precursors of this theory.

The Enistein's special relativity includes spacetime as a unified entity of space and time, relativity of simultaneity, kinematic and gravitational time dilation, and length contraction, as well as the equivalence mass-energie.

The General relativity is the relativistic theory of the gravitation, called also the geometric theory of gravitation. It is built by Einstein in 1915.

The theory relates the curvature of spacetime specified by the Einstein field equations. It is based on the differential geometry and include Ricci curvature and Christoffel symbols.

At first, the general relativity is a purely intellectual construction, for which there wasn't a possibility to experiment directly.

Here is what it looks like the Einstein's field equations:



The work of Gregorio Ricci-Curbastro, Italian mathematician (1853-1925); and Elwin Bruno Christoffel (1829 - 1900), German mathematician and physicist contribute to found the general relativity.

2. Black holes

One of the phenomena hiding in the theory of general relativity, was first described, in 1916, by Karl Schwarzschild (1873 – 1916), a German astronomer who gave a solution of the Einstein's equations.

Schwarzschild's solution showed that a small spherical object with a lot of mass would curve space-time so much that it would swallow and trap anything that came close, including light. The phenomenon was later named a black hole.

Real black holes weren't discovered until more than a decade after Einstein's death in 1955.

3. Gravitational lensing

In 1919 an eclipse if the Sun allowed to measure the deflexion of light beam by the Sun, verifying one of the major predictions the general relativity.

4. The Big Bang

It is a theory about how the universe began. Its proponents suggest that some 10 billion to 20 billion years ago, a massive blast allowed all the universe's to spring from some ancient and unknown type of energy.

The Big Bang's theory maintains that the universe expanded with incomprehensible speed from its point origin to astronomical scope. Expansion has apparently continued, but much more slowly, over the ensuing billions of years.

Scientists who studied Einstein's theory in the 1920s realized that his equations showed that the universe should be expanding, and , in the reverse, the universe would get smaller and smaller until a moment now called the Big Bang.


As with black holes, the idea was so weird that Einstein didn't believe it. He came up with a "cosmological constant" to stick in his equations to stop the universe's expansion. He finally realized he was wrong after American astronomer Edwin Hubble (1889-1953), showed that distant galaxies are moving away from us.

Einstein abandoned the cosmological constant that he had introduced so ad hoc reporting for a stationary universe and calls this introduction biggest mistake of his life.

In 1932, Einstein published with Willem de Sitter, a Dutch mathematician, physicist and astronomer (1872 - 1934), the first model of expanding Universe.

The big bang theory leaves several major questions unanswered, mainly the original cause of the big bang itself. S

5. GPs

GPs stands for Global Positioning system.

One says that the only practical, everyday use of general relativity is our cells that shows us our directions on Earth.

The general theory shows that the stronger gravity is, the slower time goes.

Time is an important variable that GPs satellites use to triangulate our location. GPs satellites are orbiting 20,000 kilometres above the Earth's surface. The weaker gravity at that distance is weak, but the about 500 trillionths of a second each second is needed in such a precise technology.

The special relativity, as well as the general relativity, most importantly, are used to correct time in the GPs technology.

6. Gravitational waves

Gravitational waves are ripples in space-time that Albert Einstein's theory of general relatively predicted would be produced by massive phenomena such as neutron stars or black holes colliding.

Those ripples will propagate through space time at the speed of light. Detecting gravitational waves would tell us whether the Einstein's general theory of relativity is really correct.

If we drew a straight line on the surface of a lake and then threw a stone into the water, producing waves, that might cause the line to curve. The same thing happens with space-time when a gravitational wave passes through.

Based on this idea, We built detectors. Presntly, They are two used detectors. Virgo in Italy, LIGO in the USA on Earth. The European eLISA detector on space is planned to be launched in 2034.

The two ground-based detectors LIGO and Virgo work on the basis of the interferometer of Michelson. Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, are located in Livingston, Louisiana, and Hanford, Washington, USA. Virgo (from Virgo cluster) is located at Cascina near Pise, Italy.

Depending on what their source is, the frequency of the graviational waves also varies. And any given detector can only detect certain frequencies of gravity waves.

LIGO and eLISA are designed to detect different frequencies of gravitational waves. LIGO should be able to detect waves made by smaller objects like neutron stars and smaller black holes up to 500 times the mass of our sun. More massive objects like colliding super-massive black holes, up to a million times the mass of the sun, will be detectable with eLISA.