In 1905 an obscure, 26-year old Assistant Examiner in the Swiss Patent Office revolutionized the world of Physics forever. Albert Einstein published four ground-breaking papers in a single year!LINKS TO RELATED POSTINGS AND RESOURCES
VISUALIZING Relativity - PowerPoint Show
VISUALIZING Relativity - Excel Spreadsheet
VISUALIZING for Science and Technology - Blog Posting
VISUALIZING Einstein's "Miracle Year" - Blog Posting
VISUALIZING My Insight Into Lorentz Gamma - Blog Posting
VISUALIZING the "Twin Paradox" - Blog Posting
1- PHOTOELECTRIC EFFECT
This paper may be considered the foundation of Quantum Theory. Einstein theorizes that Energy is not continuous, but rather comes in DISCRETE QUANTA.
2- BROWNIAN MOTION
3- (SPECIAL) THEORY OF RELATIVITY (INVARIABILITY)
Perhaps his most important paper, On the Electrodynamics of Moving Bodies, begins with a VISUALIZATION of a magnet and a coil of wire. He notes that, when the wire is held still and the magnet is moved, an electrical voltage is produced in the wire. The opposite is also true, he notes, when the magnet is held still and the wire is moved.
Einstein's critical INSIGHT was that it was the RELATIVE movement of the wire and the magnet that induced the electrical voltage.
He knew about electrical technology because his father owned a company that manufactured electrical equipment. However, by the 1880's, when Einstein was a child, many other people had this knowledge, yet, it was not until 1905, with this paper, that the critical implications of this simple VISUALIZATION were recognized.
Of course, by the time he had the insight and wrote this paper, Einstein had a diploma in Physics and Mathematics from the Zurich Polytechnic. That enabled him to extend his insight lightyears [pun intended] beyond mere electrical technology and clarify Maxwell's electrodynamics.
Einstein proposes two startling postulates:
1) "The same laws of electrodynamics and optics will be valid for all frames of reference." and
2) "Light is always propagated in empty space with a definite velocity c which is independent of the state of motion of the emitting body."
These two postulates summarize the essence of Einstein's 1905 theory, which has come to be called his SPECIAL Theory of Relativity, to distinguish it from his later 1915 GENERAL Theory of Relativity. [Special Relativity applies only to so-called Inertial frames of reference moving at a constant speed, while General Relativity extends the ideas to frames of reference that are subject to acceleration, including the effects of gravity in the vicinity of a massive body. Some commentators including me (and even Einstein at one time :^) think these theories would have been better named the Special and General Theories of Invariability.]
The first postulate of Special Relativity establishes that ALL frames of reference are equal with respect to the applicability of the Laws of Nature. Some social commentators have, IMHO, over-interpreted the applicability of this idea, claiming that everything is relative, including basic concepts of ethics. The actual meaning, IMHO, is the Invariability of the Laws of Nature, being the same to all observers, at all times and places.
The second postulate does away with the need for a "luminiferous ether" the then prevalent idea that light and other electromagnetic waves require a medium in which to propagate, the way sound waves require air, water or some other medium. Again, IMHO, some scientists have over-generalized that postulate to deny any concept of Absolute Space or Absolute Time. All Einstein says is that all attempts to measure the Speed of Light will yield the same value, which is another example of Invariability.
Quoting Einstein directly:
... the unsuccessful attempts to discover any motion of the earth relatively to the 'light medium,' suggest that the phenomena of electrodynamics as well as of mechanics possess no properties corresponding to the idea of absolute rest.and
...The introduction of a 'luminiferous ether' will prove to be superfluous inasmuch as the view here to be developed will not require an 'absolutely stationary space' provided with special properties, nor assign a velocity-vector to a point of the empty space in which electromagnetic processes take place.Thus, while sound waves require a medium for propagation, light and other electromagnetic waves do not. For example, assume I am some distance from a wall and I make a loud, sharp sound (such as a gunshot), and then measure the return-trip time between the original sound and the echo, I will measure a shorter time in still air than I will if there is a wind blowing the air towards or away from me.
The reason for this is that, for still air, the outbound and return trip will take exactly the same amount of time, while, for moving air, it will take longer for the sound going against-the-wind, and shorter for the sound going with-the-wind.
You might think the longer and shorter changes would cancel out, but that is not so, The against-the-wind slowdown will be greater than the with-the-wind speedup. To VISUALIZE that, imagine the extreme case where the wind is blowing at the speed of sound. The with-the-wind sound will get there at twice the speed of sound, but, the against-the-wind sound will never get there!
Not so with light and other electromagnetic waves. The 1887 Michelson-Morley experiment demonstrated that there was no difference in the return trip time for light signals aligned with the 67,000 Miles per Hour motion of the Earth around the Sun and those at right angles to that motion.
Thus, there is no "ether wind", but there are differences between Kinetic (and Potential) Energy levels experienced by different Observers.
IS THERE ANY SUCH THING AS ABSOLUTE SPACE AND TIME?
Consider the so-called "Twin Paradox", where the stay-at-home twin will have aged more than the rapidly-moving travelling twin when they are reunited. This has been explained by the fact the travelling twin changes frames of reference when he turns around to come back home. True, but, IMHO, the real difference is that the travelling twin has spent his life at a higher speed and thus a higher level of Kinetic Energy than his stay-at-home sibling, and thus aged more slowly.
Alternatively, imagine a stay-at-home twin who spends her life on the surface of a massive body, while her travelling sibling goes on a slow-speed journey to far-away empty space, living most of his life far from any massive body, and then slowly returning. Which will age more slowly? Well, in this case it is the stay-at-home twin! IMHO, the real difference is that the stay-at-home twin has spent her life at higher gravitational acceleration, and thus a higher level of Potential Energy than her travelling sibling, and thus aged more slowly.
OOPS! If you bought the above explanation you have to ask: "Higher Kinetic or Potential Energy with respect to what?" Well, at least with respect to his or her sibling! Higher Kinetic Energy is based on being at a speed that is greater than the speed of some reference point, is it not? Similarly, higher Potential Energy is based on being under the influence of gravitational acceleration that is greater than the acceleration of some reference point, is it not?
Thus there is some point (such as the Center of Mass of the Universe?) or points (such as Lagrange points L4 and L5?) that have lower Kinetic and/or Potential Energy levels than others, and are thus special in that residents will age more rapidly there. Perhaps there is a point (or points) in the Universe where aging is more rapid than ANYWHERE ELSE. At that (perhaps imaginary) point or points, residents experience Absolute Time (and/or Space) and are truly "At Rest" because they are at some Absolute Zero Kinetic and/or Potential Energy level.
[Note: Lagrange points, L1 to L5, are where the combined gravitational pull of two large masses provides precisely the centripetal force required to orbit with them. L4 and L5 are stable.]
4- EQUIVALENCE OF MATTER AND ENERGY
This paper is merely the source of the World's Best-Known Equation, E=Mc2