Far out cosmology: spacetime explained (Introduction)

by David Turell , Monday, July 15, 2019, 19:59 (1956 days ago) @ David Turell

It simplifies our understanding of space:

https://www.agnosticweb.com/index.php?id=28167

Einstein’s theory represented a major simplification of the underlying math.

"His 1905 theory of special relativity showed that there’s a give-and-take to space and time, which together make up the bendy, warping “space-time” fabric. Thinking this way led him and others to a closer examination of the symmetries of the universe, or all the ways you can shift, rotate and move through it and still measure the same separation between objects or events as before. It is in the language of these symmetries that relativity simplified our mathematical description of the universe.

"In fact, the math becomes even nicer when the expansion of space-time is taken into account. As the physicist Freeman Dyson pointed out, any mathematician who had thought about this while studying Einstein’s theory in its early years “would have correctly predicted the expansion of the universe 20 years before it was discovered observationally by [Edwin] Hubble.”

***

'Instead, as Einstein discovered, space and time are inextricably bound. If you move too fast through space, time necessarily slows down — a consequence, he realized, of the fact that nothing travels faster than the speed of light through both space and time together. This finite speed limit forces motion through space to curb motion through time, so that measured distances and durations depend on the state of motion of the measurer. Driving alongside the sprinter actually slows your clock relative to the stopwatch of someone in the bleachers. And yet, as Einstein’s former teacher, the geometer Hermann Minkowski, showed in 1908, the “space-time interval” between two events — each person’s combined measurements of the length of the racetrack and the sprinter’s time — always stays the same regardless of one’s point of view.

***

"Instead, as Einstein discovered, space and time are inextricably bound. If you move too fast through space, time necessarily slows down — a consequence, he realized, of the fact that nothing travels faster than the speed of light through both space and time together. This finite speed limit forces motion through space to curb motion through time, so that measured distances and durations depend on the state of motion of the measurer. Driving alongside the sprinter actually slows your clock relative to the stopwatch of someone in the bleachers. And yet, as Einstein’s former teacher, the geometer Hermann Minkowski, showed in 1908, the “space-time interval” between two events — each person’s combined measurements of the length of the racetrack and the sprinter’s time — always stays the same regardless of one’s point of view.

***

"Particles, planets, people and all other symmetry-breaking stuff stems from differences that arose during the Big Bang. As the universe inflated into existence, quantum jitter in the space-time fabric grew into macroscopic variations, which evolved into the galaxies and voids and other structures seen today. If space-time’s symmetries hadn’t spontaneously broken at the outset, the universe would now be empty and uninteresting — and no one would be around to see it. Broken symmetries are necessary for existence. (my bold)

"But as the expansion of the universe accelerates due to dark energy, all its present variations will get smoothed out like wrinkles on the surface of an inflating balloon. The universe becomes “bigger and more dilute as time goes on, driving us closer and closer to the vacuum state,” Arkani-Hamed explained. Eventually, different points of view will become truly indistinguishable. “In that vacuum state we get to see that symmetry.”

"Arkani-Hamed describes the de Sitter symmetry group as an “attractor” state that the fabric of space-time naturally tends toward. But why the universe respects the 10 de Sitter symmetries only in the infinite future, while subtly breaking them in the meantime, is “a deep question,” he said. He noted that, historically, physicists have had to dig to find the hidden, approximate, eventual symmetries of nature. “The fact that they are there is clearly some deep clue.'”

Comment: This explains the importance of the concept of spacetime as real and necessary. Time is not simply a sequence of events as our minds see it. It is built into the universe, Note my bold. At the basis of reality is the quantum state. And that is where the mind of God exists.