44 TIME 



well have abandoned the idea that we have intuitive 

 recognition of a Now other than Here-Now, which was 

 the original reason for postulating world-wide instants 

 Now. 



However, having become accustomed to world-wide 

 instants, physicists were not ready to abandon them. 

 And, indeed, they have considerable usefulness pro- 

 vided that we do not take them too seriously. They were 

 left in as a feature of the picture, and two Seen-Now 

 lines were drawn, sloping backwards from the Now line, 

 on which events seen now could be consistently placed. 

 The cotangent of the angle between the Seen-Now lines 

 and the Now line was interpreted as the velocity of light. 



Accordingly when I see an event in a distant part of 

 the universe, e.g. the outbreak of a new star, I locate it 

 (quite properly) on the Seen-Now line. Then I make a 

 certain calculation from the measured parallax of the 

 star and draw my Now line to pass, say, 300 years in 

 front of the event, and my Now line of 300 years ago 

 to pass through the event. By this method I trace the 

 course of my Now lines or world-wide instants among 

 the events, and obtain a frame of time-location for 

 external events. The auxiliary Seen-Now lines, having 

 served their purpose, are rubbed out of the picture. 



That is how / locate events; how about youf We 

 must first put You into the picture (Fig. 3). We shall 

 suppose that you are on another star moving with 

 different velocity but passing close to the earth at the 

 present moment. You and I were far apart in the past 

 and will be again in the future, but we are both Here- 

 Now. That is duly shown in the picture. We survey 

 the world from Here-Now, and of course we both see 

 the same events simultaneously. We may receive rather 

 different impressions of them; our different motions 



