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Special Relativity |
The Special Theory of Relativity is based upon the Principle of Relativity
which asserts that the laws of physics are the same in every inertial frame of reference. In
other words, there is no such thing as an absolute rest frame. All motion is
relative. And all observers may legitimately declare themselves to be at rest.
Therefore, the most fundamental properties of the universe are independent of
whoever observes them.
Although the principle of relativity seems quite reasonable (even intuitive to most people), its ultimate consequences are anything but reasonable or intuitive. For example, when the principle of relativity is applied to the properties of light one finds that the speed of light in a vacuum must be a universal constant, the same for all observers. Therefore, if we let light itself be our observer, we conclude that light must rush pass light at the speed of light and that, from the light ray's point of view, everything else in the universe must be moving along together at the same speed (in the opposite direction at the speed of light). Or if we consider the Star Trek Paradox where two inertial observers pass one another when a burst of light is emitted, we conclude that both observers must remain at the center of the expanding shell of light even though they do not remain together. Such conclusions clearly violate our common sense and stretch our imagination to the breaking point. And these are only two simple examples of the numerous paradoxes and apparent inconsistences frequently encountered in the theory of relativity.
The only way to resolve these paradoxes and remove the apparent inconsistencies in the theory of relativity is to adopt a new and different world view -- one that is consistent with the Principle of Relativity. When this is done, we find that many of the things we previously thought to be absolute in character (things like space, time and mass) are actually relative quantities. We find that other things, previously known to be relative (such as velocity, energy, and momentum), take on completely new meanings. And we find that combining these new quantities and concepts allows us to transform the time-varying, three-dimensional world-view of one observer into that of another. In other words, we are able to acquire a relativistic viewpoint of reality and to function in that environment.
But the relativistic viewpoint really focuses on the wrong thing. It focuses on the relative aspects of reality rather than the absolute aspects -- the observer dependent quantities rather than the invariant quantities. It tends to ignore the fact that the more important characteristics of reality (the fundamental principles of nature, basic laws of physics, and the important quantities they govern) must be completely independent of the observer.
Therefore, we need to move past the relativistic viewpoint and adopt a
universal, absolute, or invariant
viewpoint. Only then can we fully grasp the new relationships between
the old quantities. Only then can we build up new, more fundamental concepts
(such as spacetime, events, intervals, worldlines, light cones, four-vectors,
etc.) that are truly independent of all observers. Only then can we fully
appreciate the fact that we actually exist in a four-dimensional reality rather
than a time-varying three-dimensional world. Only then can we develop an
intuitive understanding of the relationship between space and time; between
mass, energy, and momentum; and between the various interdependent conservation
laws. Only then can we begin to master the full implications of Einstein's
Special Theory of Relativity.
Questions:
Q1. Which of the following
quantities is relativistic? Its value depends upon who observes it. (A) spacetime, (B) intervals, (C) time, (D)
basic laws of physics, (E) events.
Q2. Which of the following are
true regarding paradoxes that arise in special relativity? (A) Such paradoxes
demonstrate that the theory of relativity is inconsistent, and therefore,
invalid. (B) Such paradoxes demonstrate
that the theory of relativity is incomplete, and therefore, needs refinement.
(C) Such paradoxes demonstrate that the person puzzled by the paradox does not
understand some of the basics of relativity because such paradoxes can always
be resolved. (D) More than one of these. (E) None of these.
Q3. If an observer were traveling
at a speed essentially equal to that of light relative to the universe, which
of the following would be true for that observer. (A) The universe would be
moving essentially at the speed of light opposite the observer’s motion.
(B) The universe would remain essentially at rest. (C) Light would slowly creep
pass the observer in the direction he is moving. (D) Light would rush past the
observer at essentially twice the speed of light in the direction opposite his
motion. (E) Light would remain
essentially at rest.
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