The General theory of relativity: four steps taken by the genius

The Revolutionary physicist used his imagination, not complex math to come up with their most famous and elegant equation. The General theory of relativity is known that foretells a strange but true phenomena, like the aging astronauts in space compared to humans on Earth and changes in the forms of solid objects at high speeds.

But interestingly, if you take a copy of the original papers of Einstein on relativity in 1905, it is pretty easy to disassemble. The text is simple and understandable, and mostly algebraic equations — they will be able to disassemble any high school student.

All because of the complex math was never strong suit of Einstein. He liked to think imaginatively, to experiment with your imagination and conceptualize them as long as the physical ideas and principles will not be visible crystal clear.

Here is how it began thought experiments of Einstein, when he was only 16 years old, and how they ultimately led him to the most revolutionary equation in modern physics.

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1895: running near the beam of light

By this time the life of Einstein his ill-concealed contempt for the German roots of the authoritarian educational methods in Germany have played a role, and he was expelled from high school, so he moved to Zurich in the hope of admission to the Swiss Federal Institute of technology (ETH).

But first, Einstein decided to spend a year training at the school in the nearby town of Aarau. In this place he soon discovered that wondered what it was like to run alongside a ray of light.

Einstein had already learned in a physical class, what is the beam of light: a set of oscillating electric and magnetic fields moving at the speed of 300 000 kilometers per second measured the speed of light. If he would run near the same speed, Einstein realized he could see a lot of oscillating electric and magnetic fields around him, as if frozen in space.

But it was impossible. First, the stationary field would violate Maxwell's equations, the mathematical laws, which were laid all physicists knew about electricity, magnetism and light. These laws were (and still are) quite strict: any waves in these fields should move at the speed of light and can't stand still, no exceptions.

Worse, stationary fields are not in keeping with the principle of relativity, which was known to physicists since the time of Galileo and Newton in the 17th century. In fact, the principle of relativity says that the laws of physics can't depend on how fast you move: you can only measure speed of one object relative to another.

But when Einstein applied this principle to my thought experiment, there is a contradiction: relativity dictated that all he could see, moving near the beam of light, including a stationary field must be something mundane that physicists can create in laboratories. But this has never been observed.

This problem will excite Einstein 10 more years, throughout his learning path and work at ETH and movements to the Swiss capital Bern, where he will become an examiner in the Swiss patent office. It is there that he will resolve the paradox once and for all.

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1904: the measurement of light from a moving train

It wasn't easy. Einstein tried every solution that came to his mind but nothing worked. Almost in desperation, he began to ponder, but simple, but radical solution. Perhaps Maxwell's equations work for all, he thought, but the speed of light was always constant.

In Other words, when you see a passing light beam, no matter whether its source is moving toward you, from you, to the side or somewhere else, and no matter how fast its source is moving. The speed of light you measure will always be 300,000 kilometers per second. Among other things, this meant that Einstein never see a stationary oscillating field as will never be able to catch a beam of light.

It was the only way I saw Einstein to reconcile Maxwell's equations with the relativity principle. At first glance, however, this decision had its own fatal flaw. Later he explained it with another thought experiment: imagine a beam that runs along the railway embankment, while the train passes in the same direction at a speed, say, 3000 kilometers per second.

Someone standing near the mound will have to measure the speed of the light beam and to the standard number of 300 000 kilometers per second. But someone on the train will see the light moving with the velocity of 297,000 km / sec. If the speed of light is intermittent, Maxwell's equation inside the car should look different, concluded Einstein, and then the principle of relativity will be violated.

This seeming contradiction was caused Einstein to think for almost a year. But then, one morning in may 1905, he went to work with his best friend Michel Besso, an engineer, whom he knew since student years in Zurich. The two men talked about the dilemma of Einstein, as always. And suddenly Einstein saw the solution. He worked on it all night and the next morning when they met, Einstein said Besso: "Thank you. I completely solved the problem."

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May, 1905: lightning strikes moving train

Einstein's Revelation was that observers in relative motion perceive time differently: it is possible that two events will occur simultaneously from the point of view of one observer, but at different times from the point of view of another. And both the observer would be right.

Later Einstein illustrated his point another thought experiment. Imagine that next to a railway again the observer is, and past him, carried by the train. In that moment, when the center point of the train passes the observer, at each end of the train hit by lightning. Because lightning hit at the same distance from the observer, their light gets in his eyes at the same time. It's fair to say that the lightning hit at the same time.

Meanwhile, exactly in the centre of the train there is another observer. From his point of view, the light from the two lightning strikes is the same distance and the speed of light is the same in any direction. But since the train is moving, the light coming from the back of lightning, must travel a longer distance, so it hits the observer a few moments later than the light from the beginning. Because the light pulses arrive at different times, we can conclude that the lightning strikes are not simultaneous one is faster.

Einstein realized that this relative simultaneity. And once you acknowledge this, strange effects that we now associate with relativity, are resolved using simple algebra.

Einstein feverishly wrote down his ideas and submitted his work for publication. The title was "On the electrodynamics of moving bodies", and it reflects the attempt of Einstein to reconcile Maxwell's equations with the relativity principle. Besso was made special thanks.

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September 1905: the mass and energy

This first work, however, did not last. Was Einstein obsessed with relativity until the summer of 1905, and in September sent the second article to be published, already, after, in retrospect.

It was founded on a single thought experiment. Imagine an object at rest, he said. Now imagine that simultaneously emits two identical light pulse in opposite directions. The object will stay in place, but since each pulse takes a certain amount of energy contained in an object, the energy will decrease.

Now, Einstein wrote, will look like this process for the moving observer? From his point of view, the object will simply continue moving in a straight line, while the two impulses will fly. But even if the speed of the two pulses will remain the same — the speed of light — their energy will be different. The momentum is moving forward in the direction of movement, will have a higher energy than one that moves in the opposite direction.

Adding a little algebra, Einstein showed that for all it was consecutive, the object should not only lose energy when sending light pulses, but also a lot. Or mass and energy must be interchangeable. Einstein wrote the equation which connects them. And it became the most famous equation in science: E = mc²....