Galilean-Newtonian space-time

In this architecture, there is an acknowledgement that there is no absolute state of rest: everything is moving from some or other perspective. The natural state of a free object now is uniform motion relative to the distant stars.

Minkowski spacetime

In his radical vision of space and time, Minkowski thought of them as part of a single, absolute, four-dimensional continuum that we refer to as spacetime (no hyphen) [Petkov, 2012]. Different inertial frames of reference cut across this structure in different ‘directions’, each frame giving its own space and time coordinates to an event, or point in spacetime.

Multi-fingered time

Different observers in Minkowski’s spacetime carry their own clocks: these tick away according to their individual ‘proper’ times, rates determined by the specific worldlines or tracks that each clock traces out in spacetime. There are as many separate, individual times as there are clocks, giving a truly ‘multi-fingered’, endophysical architecture of time. This is the origin of the Twin Paradox, discussed in Chapter 17. Inertial frames of reference are idealizations composed of a ‘chorus’, a continuum of observers moving in a coordinated way with their clocks synchronized and their relative positions in ‘space’[1] fixed.

  • [1] ‘Space’ being the usual three-dimensional position space that each chorus imagines it is sitting atrest in.
 
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