The passage of time is one of the things with which we are instinctively, unthinkingly comfortable; and yet when pressed to describe what time actually is, we are as flummoxed now as we ever were.
The Greek philosopher Heraclitus said you could never step in the same river twice – and was promptly corrected by some smartypants who pointed out that you can never step in the same river once. David Bowie put it more straightforwardly. ‘Time may change me,’ he sang, ‘but I can’t trace time.’
We think of time as travelling (already a spatial metaphor): but travelling relative to what?
We agree that it passes. But at what speed? One second per second? We commonly think of it as a property that obtains throughout the universe – Newton certainly did, at least, and his is the instinctive position to take. But Einstein demonstrated that it’s all stirred up with space (‘time is now everywhere’, in the context of general relativity, isn’t such a daft thing to say), and it goes slower the faster you travel.

In Search of Time
I just started this book so hopefully this will hold you over until I post my review.
The passage of time is one of the things with which we are instinctively, unthinkingly comfortable; and yet when pressed to describe what time actually is, we are as flummoxed now as we ever were.
The Greek philosopher Heraclitus said you could never step in the same river twice – and was promptly corrected by some smartypants who pointed out that you can never step in the same river once. David Bowie put it more straightforwardly. ‘Time may change me,’ he sang, ‘but I can’t trace time.’
We think of time as travelling (already a spatial metaphor): but travelling relative to what?
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