# Shared Flashcard Set

## Details

Moore 3
The Nature of Time
11
Physics
10/05/2009

Term
 Newtonian time
Definition
 There is only one kind of time; we could measure all events with 1 moving clock that happened to be present at each event.
Term
 Coordinate time
Definition
 the time measured between two events either by a pair of synchronized clocks at rest in a given inertial reference frame (one clock present at each event) or by a single clock at rest in that inertial frame (if both events happen to occur at that clock in that frame). it is delta t. it is frame dependent i.e. the value varies according to which frame you choose to measure it in.
Term
 coordinate time differences are relative
Definition
 i.e. they deoend on one's choice of inertial frame--each observer will conclude that the clocks in the other frame are not synchronized. They will also disagree about the spatial separation between the events.
Term
Definition
 send out a pulse of light--measure the time it takes to come back. works because speed of light is the same in all reference frames
Term
 Geometric analogy for coordinate time
Definition
 Just as people using Cartesian coordinate systems oriented in different directions would get different (x,y) values for specific points on their respective grids, so do observers with different inertial frame get different coordinate time values for specific events.
Term
 distance and pathlength
Definition
 On Cartesian coordinate grid, the distance between two points(like when you draw a straight line between them) is indisputable--it is coordinate-independent. So is path-length, or the distance of the path that you take from the one point to the other.
Term
 3 kinds of spatial separation
Definition
 coordinate separations, path-length, and distance.
Term
 proper time
Definition
 the time between two events measured by any clock present at both events. it is frame-independent. it is analogous to the spatial concept of path-length.
Term
 Hafele and Keating experiment
Definition
 two synchronized atomic clocks; one is flown around the world, the other stays put. (both measured the proper time of the departure and return of the one clock). They differed by several nanoseconds; that proper time depends on the clock's worldline is an established experimental fact
Term
 spacetime interval
Definition
 The proper time measured by an inertial clock present at both events. It is frame-independent and depends on the separation of the events in space and time and nothing else. It is analogous to the spatial concept of distance.
Term
 particularities of the spacetime interval
Definition
 The spacetime interval is a very specific proper time and it is also a coordinate time
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