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Block Time: Imagine a loaf of bread

sterrab's picture

The distinction between past, present and future is only an illusion, even if a stubborn one. -Albert Einstein

I talked to my physics advisor (Prof. Mark Matlin) about blocktime. He helped me better understand how time can be understood as a timescape, given the spacetime continuum where time is a fourth dimension similar to space.

I posted the video "The Fabric of Cosmos: The Illusion of Time" by Brian Greene, famous theoretical physicist and string theorist, above. Around the 18th minute, he describes how spacetime can be analogized to a loaf of bread (22nd min). Similar to the different ways a loaf of bread may be sliced, each observer's reference frame (depending on speed relative to one another) determines what parts of the 3D space is observed. The figure below includes two reference frames where Observer 2's frame of reference is moving at a speed relative to Observer 1's frame. As such, the space that is mapped at out for Observer 2 is much different from Observer 1's observation (as shown by the inclination of mapped space planes). Although the time may be defined to be the same (t2, t1, or any arbitrary time), the observations are different and events on each "mapped space" will not be simultaneous.

Back to blocktime: Different events/observations may be witnessed by 2 observers at each one's "now". As such, there is no distinction of a "now". One's "now" can be someone else's near future or distant past and time hence includes both the now, the past, and the future.



About Time: Einstein's Unfinished Revolution, Paul Davies

The Fabric of the Cosmos: The Illusion of Time, Brian Greene

Blocktime according to physicist Brian Greene