No Einstein, no solar system
A century ago, there was a big problem, so that the use of an Einstein was not able to solve.
"Learn from yesterday, live for the moment, looking forward to tomorrow. It is important not to stop questioning."
- Albert Einstein
For thousands of years, throughout human history, the nine planets and the moon is our only cognition to the vagaries of the universe.
Stars and the Milky Way night after night, year after year, always the same, or change too little and too slow, so that human never notice to them.
Attentive person can discover, planetary motion is not arbitrary, but there are telltale signs, divided into anterograde and retrograde.
Explain their movement in the sky there are two main methods:
1, geocentric theory, namely the planet to the earth as the center.
2, heliocentric theory, namely the planet to the sun as the center, and the earth is only one of these planets.
Nearly two thousand years, is popular is the former.Copernicus is put forward in the 16th century, after the latter Galileo, Kepler's study strongly support the heliocentric theory, eventually completed by Isaac Newton of the heliocentric theory unify river's lake.
Newton's breakthrough is the greatest, because he not only describes the performance of these planets -- a elliptical orbit around the sun -- also gives the expression to the new mechanism: the law of universal gravitation.The law of gravity applies not only to the earth, also applies to all objects.
It explains why satellite orbiting the parent star, why is the comet can be repeated and often disturbed by other planets, why on earth tide, and why the planets will not interfere with each other.
The law of gravity also explains some of the more subtle phenomenon, some long before noticed the phenomenon of later generations.
If the universe contains only two point: the sun and a planet, then the orbit of the planet will be perfect oval, every week finishing moves around the sun will return to its starting point.
Under the framework of Newtonian mechanics, however, there are many quality body in the solar system, the elliptical precession or turn in its own orbit.In the middle of the 19th century, the orbit of Uranus bias led to the discovery of Neptune is because Neptune's gravity to Uranus perturbation.
In the inner solar system, however, the mercury closest to the sun in a similar situation.
Specific and accurate observation by the 16th century (thanks to tycho brahe), we were able to measure how perihelion precession of the mercury, calculate the numerical value is slow to incredible Angle of 5600 seconds per century: 1.5 degrees in one hundred many!5025 of them arc seconds the equinox from earth, Angle of 532 seconds from Newton's gravitational pull.
But the thing: 5025 + 532 is not equal to 5600, although less approximate 5600 much.So, why?
Natural, explain several kinds:
1, maybe wrong data.After all less than one percent of the error as if nothing worthy of panic.But error is less than 0.2% means that data can be trusted.
2, may have planets than mercury is closer to the sun.This explanation is predicted and Mr Ben levy of Neptune is proposed.After a thorough search, however, did not find other stars.
3, Newton's laws of mechanics might need to fine tune.Inverse square law may not be accurate enough, 2 in the r2 precision is not 2.0, but 2.0000000 a few.This explanation is proposed person is Simon newcomb and went o hall.
However, these explanations are not satisfactory.
Until Einstein in the basis of studying the poincare and minkowski space and time will be unified as a whole, released on November 25, 1915, the general theory of relativity, the formula to the mercury per one hundred precession is 43 ", finally explain previous observations made.
Astronomy and physics caused quite a stir.Less than two months later, Karl schwarzschild Einstein gravitational field equation is obtained by calculation of a vacuum, predicted the existence of black holes.Star's migration and gravity, red/blue shift in the observation was confirmed.Finally, the total solar eclipse of 1919 confirmed the correctness of the theory of relativity, general relativity replaced the Newton's law of gravitation.
Since then, the predictions of the theory of relativity from gravitational lensing, inertial system drag effect to the orbital decay and we have confirmed the other one.Observations from no conflicts with the theory at a time.
A century later, more advanced means of observation and for the further understanding of the solar system to increase the precision of the precession of perihelion of mercury to every one hundred seconds, in the corner of percentage theory and observation of front face uncertainty continues.
The next century, what are the new discovery and new possibilities?We have to wait and see.