During a 4 month period from March to June 1905, Einstein wrote 4 papers and his doctoral dissertation. In a very casual and understated letter written to his friend Conrad Habicht, he announced his intentions.
Dear Habicht,
Such a solemn air of silence has descended between us that I almost feel as if I am committing a sacrilege when I brek it now wiht some inconsequential babble.. So what are you up to, you frozen whale, you smoked dried canned piece of soul...? Why have you still not sent me your dissertations? Don't you know that I am one of the 1&1/2 fellows who would read it with interest and pleasure, you wretched man? I promise you four papers in return. The first deals with radiation and the energy properties of light and is very revolutionary, as you will see if you send me your work first. The second paper is a determination of the true sizes of atoms... The third proves that bodies on the order of magnitude of 1/1000 mm, suspended in liquids, must already perform an observable random motion that is produced by thermal motion ... The fourth paper is only a rough draft at this point, and is an electrodynamics of moving bodies which employs a modification of the theory of space and time.
The four papers he was talking about were,
1. Concerning an Heuristic Point of View Toward the Emission and Transformation of Light, which is an explanation of the photoelectric effect.
2. On the Movement of Small Particles Suspended in Stationary Liquids Required by the Molecular-Kinetic Theory of Heat, which was his successful third attempt at getting a doctoral thesis.
3. On the Electrodynamics of Moving Bodies, concerning his Invention of the theory of special relativity, and finally,
4. Does the Inertia of a Body Depend upon its Energy Content? which extends his invention of the theory of special relativity, and introduces the E = mc2 equasion.
To come up with these great ideas, Einstein had to dispense with 2 generations of belief that there was an all pervading "ether" AND assert that light is both a wave and a (quanta) photon. To do this, he had to answer the question, "What is light?" and "Why is the velocity of light always 186,000 miles per second?" To figure out the answer to this question required Einstein to make one of the most astounding realizations in science.
1. The nature of light: One of the great mysteries of Einstein's time was how was light transmitted? Was it "sprayed" out in a shower of particles or photons? Or was it something else? As Einstein started to ponder this he had to think of what it would mean if light was in the form of particles rushing forth from a source. One of the problems in this is that if light was in the form of particles or photons, then if it were emanating from a source at it's known velocity of 186,000 miles per second, then if the source were moving towards you at say, 10,000 miles per second, then the velocity of light would appear to you to be moving towards you at 196,000 miles per second. But tests had shown that regardless of where the light was coming from, or how fast the source was moving towards you or away from you, it was always a constant 186,000 miles per second. That didn't make sense to Einstein (or anybody else). Equally as disturbing was the fact that if the light were stationary, and the recipient were moving (say, on a train) either towards the source, or away from the source, the velocity of the light still remained at 186,000 miles per second. If light were in the form of particles or beams, then the only way it could maintain a constant velocity, regardless of how fast the source was moving, or the recipient, would be if the particles were encoded, or otherwise knew that how fast the source and recipient was moving. Test showed that this was not the case.
Another mystery was how did light move through space? The generally accepted notion was that space was composed of a type of super, seemingly imperceptible, low viscosity "ether" that served as a medium for the light particles or waves to pass through, much like water conducted waves, or atmospheric gases carried the force of wind. Despite many experiments, this "ether" could not be detected.
2. While walking and talking to his friend, Michaela Besso, Einstein was suddenly hit with one of the most profound realizations in the history of mankind. Suddenly the point of conjecture that had perplexed man for years, was illuminated. Einstein realized that if light was a constant, then time can not be absolutely be defined. TIME itself must be a variable.. This realization changed physics from that day forward. Newton had contemplated this problem in his day, and to solve it he resorted to the conclusion that the divine being was the one watcher that had been observing existence from the moment of it's creation. From the time that Einstein made his realization, It was only a mere 5 weeks before he produced the paper, "The electrodynamics of moving bodies".
Einstein explained the concept in the following way (paraphrased). Two events that appear to be simultaneous to one observer, may not be simultaneous to a second observer, therefore, there's no way to prove that the event was simultaneous.
Einstein used a thought experiment to illustrate this. suppose two lightning bolts strike opposite sides of a railroad embankment, we may define the strikes as simultaneous if we are standing exactly between the two strikes, HOWEVER, if there is someone on a train and they were rushing towards one one of the lightning strikes it will appear to them that the lightening bolt they are heading towards will strike before the other one. The point is that two different individuals will perceive the same event as happening at different times, or at the same time, depending upon their perspective. The point? Time is relative.
While explaining his paper at a conference, a question arose from the audience. Someone wanted to know if in Einstein's universe, since time was relative, would it be possible for twins to age differently? Einstein paused for a few seconds and then answered, "Yes". This question and answer, is now what is known as the "twin paradox".
If one twin went on a round-trip to a destination 21 light years away traveling at the speed of light, upon returning, 42 years would have passed on Earth, but only 12 hours, would have passed on the spaceship. . . If the trip were to the edge of the known universe (9 billion light years away), and back, although 18 billion years would have passed on Earth, only 1 day and 6 hours would have passed on the space ship. . . In Einstein's concept of general relativity, there is space/time seeing as they are both relative.
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