Operational interpretations of the four-dimensionality of our universe and of the reference "frames" of relativity theory are presented. The interpretations display a property intriguingly similar to the Pauli exclusion principle of quantum physics.In this paper, operational interpretations of the four dimensions of our universe and of the reference "frames" of relativity theory are given. These interpretations involve a "'geometric Pauli property" intriguingly similar to the Pauli exclusion principle of quantum physics.We begin with an operational interpretation of the familiar "event" of relativity theory (Taylor and Wheeler, 1966). The event is operationally identifiable. That is, several observers can and do agree that a particular event has occurred and that it is one and the same event. For example, consider the flash of a flashbulb. Everyone who observes the flash can agree that there was an event and that there was just one event. No nonobserver denies that there was an event. And furthermore all observers and nonobservers can and do agree, in some approximation, that only one flashbulb flashed. We know from experience that we can and do agree on such things. Other examples of operationally identifiable events are collisions. For example, collisions between two trains or two cars, the touchdown of an aircraft, the catching of a ball, the kicking of a ball, are all operationally identifiable events. We then view the universe as the set of all such operationally identifiable events.The four dimensions of the universe then might have the following operational interpretation: the events which constitute the nearby universe are so connected that we can assign a unique ordered 4-tuple of real numbers to each constituent event. "Unique" here means that no two events share the same ordered 4-tuple. Furthermore, the connection is such that the ordered © 19"/5 Plenum Publishing Corporation. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission of the publisher.
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