242 SCIENCE AND THE HUMAN MIND 



conceptual space became filled with turbulent motion, 

 with interlinked vortex filaments, even with solid, 

 densely packed spheres. 



But worse difficulties remained. If space be filled 

 with a stagnant aether, it must either be unaffected 

 by the movement through it of ordinary matter, or 

 the moving matter must disturb it, and carry some of 

 it along in the path of motion. For instance : was the 

 aether near the surface of the earth moving with it, 

 or was it at absolute rest in space ? A test was 

 possible on the velocity of light. Was that velocity 

 the same in the direction of the earth's motion as 

 across it ? In a famous series of experiments, Michel- 

 son and Morley found no relative movement between 

 the earth and the aether, and concluded that the 

 earth swept an atmosphere of aether along with it. 



On the other hand, Lodge, who sought to detect 

 the drag of the aether by whirling masses of steel, 

 found no effect. However fast the steel moved, it 

 left the aether just outside it at rest. Similar dis- 

 crepancies came to light in other optical problems. 



An explanation of the result of the Michelson- 

 Morley experiment was offered simultaneously by 

 Fitzgerald and by Lorentz. If matter be an electrical 

 manifestation, the forces between its particles, and 

 therefore its dimensions, might change as it moved 

 through the aether, and this change of size in Michelson 

 and Morley's apparatus might just compensate for 

 the effect they sought. 



But whether this explanation were right or no, the 

 authority of the aether remained supreme. No one 

 doubted the fundamental validity of the conception. 

 Indeed, attempts were constantly made to express 



