Relativity From a Relative Layman Quiz

Answer: The electrical and magnetic vibrations (fields) were perpendicular to the direction of motion and perpendicular to one another.

In the late 19th century, it was assumed that the medium through which light moved, the ether, was an absolute reference frame. This being the case, if the earth were moving in a particular direction relative to the ether, and a beam of light was emitted from a source and reflected back along the direction of this motion, the light beam would travel faster than a beam directed perpendicular to the motion. Michelson and Morley conducted a famous experiment to demonstrate this difference in the speed of light and confirm the existence of ether.

Answer: They were mere mathematical constructs, unexplained on the basis of underlying principles.

The problem was, then, that two different observers, moving at constant but different speeds, obtained different results when they measured objects moving at or near the speed of light. Although Lorentz developed equations that accurately predicted the difference in these "relative" measurements, Lorentz did not provide any model to explain his equations.

Answer: If the medium existed, it would not be possible to detect it.

Michelson never accepted relativity and continued to conduct additional experiments using refined versions of the original apparatus. Even after Michelson's death in 1931, Kennedy and Thorndike conducted one additional similar experiment in 1932.

Answer: Each will see the other's meter ruler as shorter than their own.

The meter sticks shorten and the clocks run slower. These effects on length and time are often termed "the Lorentz-Fitzgerald contraction" and "time dilation", respectively. After the failure of the Michelson and Morley experiment, George Fitzgerald and Hedrick Lorentz independently proposed that length "contraction" could explain the results. Each man later tried to give the other a greater share of the credit for originating the idea.

Answer: The speed of light and the laws of physics

Lorentz did not provide any model to explain his equations. Not only was this state of affairs unsatisfactory to Lorentz, it prompted Albert Einstein to question what might be constant, that is what might not depend on the relative speeds.

Answer: The theory of invariants

Einstein sought to determine what was invariant in all reference frames. Accordingly, Einstein's original title for his theory was the "Theory of Invariants". (Max Planck persuaded Einstein to change it to the "Theory of Relativity.") Einstein is often wrongly quoted as having said, "Everything is relative." He did not.

In fact, Einstein became disenchanted with quantum theory in large measure because of the inherent uncertainty that quantum theory requires. After completing his work on relativity, Einstein spent the rest of his career unsuccessfully attempting to devise a "unified field theory" that would explain all known forces and banish Heisenberg's uncertainty principle.

Answer: multiply

As velocity approaches "c", the speed of light, the "gamma" approaches infinity. This implies that the mass approaches infinity as the velocity of a particle approaches that of light. Practically speaking, as the mass of the particle increases to infinity the amount of energy needed to accelerate particle further does as well. Because infinite energy is never available, only a particle with zero mass could ever reach the speed of light.

Answer: Lengthened

Time dilation can be used to advantage in particle accelerators. The Stanford Linear Accelerator website uses the "tau" particle as an example. At rest, a "tau" particle has a half-life of only 3.05 x 10 raised to the minus 13th power, seconds. In a particle accelerator, increasing the speed of the particle will not only prolong the length of time before the particle decays, but will also result in it traveling a greater distance in the accelerator before the decay occurs. Both factors allow for more observations to be made.

Answer: E = m times c squared

E equals m times c squared is almost certainly the most famous equation arising out of Einstein's theory of relativity. It led Einstein and other physicists to postulate (and ultimately warn President Roosevelt about) the possibility of producing atomic bombs.

Answer: It is a theory largely dealing with gravitation and treats acceleration and gravitation as equivalent in a number of aspects.

General relativity remains to be reconciled with quantum theory. A number of predictions of general relativity have been confirmed. The geometry and mathematics of general relativity go considerably beyond the abilities of this quiz author. Interestingly, Einstein himself received help with some of the geometric aspects from colleagues. Einstein once quipped, "Do not worry about your problems with mathematics, I assure you mine are far greater."