The Physics of Star Trek Read Online Free Page B

problem. But as also often occurs whenever great leaps are
     made in physics, Einstein's results created more questions than they answered.
    Einstein's solution, forming the heart of his special theory of relativity, was based on a
     simple but apparently impossible fact: the only way in which Maxwell's theory of
     electromagnetism could be self-consistent would be if the observed speed of light was
     independent of the observer's speed relative to the light. The problem, however, is that
     this completely defies common sense. If a probe is released from the
    
    
     Enterprise
    
    
     when the latter is traveling at impulse speed, an observer on a planet below will see the
     probe whiz past at a much higher speed than would a crew member looking out an observation
     window on the
    
    
     Enterprise.
    
    
     However, Einstein recognized that Maxwell's theory would be self-consistent only if light
     waves behaved differentlythat is, if their speed as measured by both observers remained
     identical, independent of the relative motion of the observers. Thus, if I shoot a phaser
     beam out the front of the
    
    
     Enterprise,
    
    
     and it travels away from the ship at the speed of light toward the bridge of a Romulan
     Warbird, which itself is approaching the
    
    
     Enterprise
    
    
     at an impulse speed of 3/4 the speed of light, those on the enemy bridge will observe the
     beam to be heading toward them just at the speed of light and not at 13/4 times the speed
     of light. This sort of thing has confused some trekkers, who imagine that if the
    
    
     Enterprise
    
    
     is moving at near light speed and another ship is moving in the opposite direction at near
     light speed, the light from the
    
    
     Enterprise
    
    
     will never catch up with the other ship (and therefore the
    
    
     Enterprise
    
    
     will not be visible to it). Instead, those on the other ship will see the light from the
    
    
     Enterprise
    
    
     approaching at the speed of light.
    This realization alone was not what made Einstein's a household name. More important was
     the fact that he was willing to explore the implications of this realization, all of which
     on the surface seem absurd. In our normal experience, it is time and space that are
     absolute, while speed is a relative thing: how fast something is perceived to be moving
     depends upon how fast you yourself are moving. But as one approaches light speed, it is
     speed that becomes an absolute quantity, and therefore
    
    
     space and time must become relative!
    This comes about because speed is literally defined as distance traveled during some
     specific time. Thus, the only way observers in relative motion can measure a single light
     ray to traverse the same distancesay, 300 million metersrelative to each of them in, say,
     one second is if each of their “seconds” is different or each of their “meters” is
     different! It turns out that in special relativity, the “worst of both worlds” happensthat
     is, seconds and meters both become relative quantities.
    From the simple fact that the speed of light is measured to be the same for all observers,
     regardless of their relative motion, Einstein obtained the four following consequences for
     space, time, and matter:
    (a) Events that occur for one observer
    
    
     at the same time in two different places
    
    
     need not be simultaneous to another observer moving with respect to the first.
    
    
     Each person's “now” is unique to themselves. “Before” and “after” are relative for
     distant events.
    (b) All clocks on starships that are moving relative to me will appear to me to be ticking
     more slowly than my clock.
    
    
     Time is measured to slow down for objects in motion.
    (c) All yardsticks on starships that are moving relative to me will appear shorter than
     they would if they were standing still in my frame.
    
    
     Objects, including starships, are measured to