I love to try to figure this stuff out, even though I don’t have a good grasp of the physics. I wonder if time passes for a photon. At the speed of light, distance contacts to zero on the direction it is traveling, so it’s like being everywhere along its path once.ajax18 wrote: ↑Wed Oct 20, 2021 2:11 pmThat makes much more sense the way you explain that. What I get hung up on is the fact that time always seems to be passing. I can't really conceive of time not passing. Perhaps if you're somehow everywhere at once?Physics Guy wrote: ↑Wed Oct 20, 2021 9:07 amThis may not be quite the concept of time that y'all are discussing but it might be a sidelight. Physics seems ambiguous about what exactly time is.
In quantum mechanics time is a measure of change. "How things are" is a vector in unimaginably many dimensions, and as time proceeds the vector rotates around through those many directions. It's as if you're watching a movie as it plays. However things used to be, that no longer exists; however they may be going to become, that does not exist yet. Only the present is real.
The perspective of Einsteinian relativity, on the other hand, says that time is just like space, only different. In particular the speed of light is really just a unit convention, like the way there are special units of length associated with horses. A furlong is nothing but a certain fraction of a mile, a hand is nothing but so many inches, but horse heights are in hands and horse races in furlongs. In the same way that a hand is four inches, a nanosecond is about a foot.
The reason for using our traditional time units, of course, is that if you're dealing with a situation in which lengths are a few feet, then a foot of time (being a nanosecond) is probably far too short a time for convenient use. You're probably dealing with durations of at least several seconds, so billions of feet. If you're going to be using feet for all your lengths and Gigafeet for all your times, well, those are different words for the units anyway, so you might as well call the Gigafeet seconds—as we do.
If a foot is a nanosecond, then what distance is a year? A light-year, of course. The speed of light is simply the conversion factor between our units for space and for time. It's not really a number that God had to choose.
Anyway the implication of time being just like space is that past, present, and future are all always there, the same way New York and LA and Chicago are all always there. We just move from one to the other. We've left the past behind (and we won't go back there again); we haven't yet arrived at the future. But those other times beside the present are still real and still there, like Paris or Tokyo, even when we don't happen to be there as well.
Which perspective is right? I don't think anyone can really say right now. Perhaps in the future.
From a philosophical perspective do you think it's possible for God or any other being to see the future. And if God were to reveal the future to a being in the past and changed his actions according to a warning, would that not be backward causation and illogical? I guess it's similar to the question of is it possible to go back in time and kill your granparents?
Since a mysterious stranger didn’t kill your own grandparents before your parents were born, doesn’t that mean that you never go back and do it?