64 



THE ANATOMY OF SCIENCE 



occurs one centimeter to the right of the knot 

 O, and about two minutes and a half from the 

 beginning of the experiment. The whole dia- 

 gram is a map of the loca- 

 tion of the beads in space 

 and time. 



A heavy pendulum with 

 an ink brush attached to it 

 traces its own space-time 

 diagram upon a sheet of 

 paper moving uniformly 

 beneath it (Figure 12). 

 Both of these figures record 

 only motion in a single line, 

 and this is all we can do 

 with a plane diagram. But 

 if we employ a solid model, 

 using the two horizontal 

 directions for position in 



Space-Time Map of space, and again the verti- 



a Pendulum i t i* /• •!• 



cal directions tor position 



in time, we could record motions upon a plane 



surface, for example, balls upon a billiard table. 



The sun and planets move nearly in a single 



plane, and I have attempted to construct a 



model showing the space-time map of the sun 



and the first three planets, a photograph of 



Figure 12 



