THE RELATIVITY OF SPACE. 95 



reality it would be better to say that as space is 

 relative, nothing at all has happened, and that it is 

 for that reason that we have noticed nothing. 



Have we any right, therefore, to say that we know 

 the distance between two points ? No, since that 

 distance could undergo enormous variations without 

 our being able to perceive it, provided other distances 

 varied in the same proportions. We saw just now 

 that when I say I shall be here to-morrow, that does 

 not mean that to-morrow I shall be at the point in 

 space where I am to-day, but that to-morrow I shall 

 be at the same distance from the Pantheon as I am 

 to-day. And already this statement is not sufficient, 

 and I ought to say that to-morrow and to-day my 

 distance from the Pantheon will be equal to the same 

 number of times the length of my body. 



But that is not all. I imagined the dimensions of 

 the world changing, but at least the world remaining 

 always similar to itself We can go much further than 

 that, and one of the most surprising theories of modern 

 physicists will furnish the occasion. According to 

 a hypothesis of Lorentz and Fitzgerald,* all bodies 

 carried forward in the earth's motion undergo a de- 

 formation. This deformation is, in truth, very slight, 

 since all dimensions parallel with the earth's motion 

 are diminished by a hundred-millionth, while dimen- 

 sions perpendicular to this motion are not altered. 

 Put it matters little that it is slight ; it is enough 

 that it should exist for the conclusion I am soon 

 going to draw fnjm it. Besides, though I said that 

 it is slight, I really know nothing about it. I have 

 myself fallen a victim to the tenacious illusion that 



* Vide infra. Book III. Chap. ii. 



