This work has been selected by scholars as being culturally important and is part of the knowledge base of civilization as we know it. This work is in the public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work. Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. To ensure a quality reading experience, this work has been proofread and republished using a format that seamlessly blends the original graphical elements with text in an easy-to-read typeface. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.
"Einstein assumed nature to be such that the total four-dimensional interval between any two events, when computed from event to event along the actual succession, has a maximum value."
No matter in space and time, only intervals between events.
This book with some statements like the above provides a good distillation of relativity.
Argues that the ether is not ruled out by relativity only that it is not needed for it, I would agree if it is qualified that a mechanical ether is indeed ruled out but not some sort of luminiferous ether.