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Can We Escape from Time?

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Re: Can We Escape from Time?

#11

Post by Razengan »

brianberns wrote: post #5

"'There is no difference between Time and any of the three dimensions of Space except that our consciousness moves along it,' says the Traveller. That turned out, amazingly and counterintuitively, to be true. 'In surprisingly short order this notion would become part of the orthodoxy of theoretical physics,' says Gleick." What? Spacetime does contain four dimensions, but the whole reason that time travel is fiction,…

I wonder. If the universe is deterministic, and nothing is random, then Time could be thought of as a vector whose values encompass all the properties of everything in existence and the direction of changes in each of them. If we knew all the "rules" that govern those changes and could make a simulation that captured the current state of everything, we could traverse back and forth along that vector (but probably not beyond the instant when that simulation was turned on, because then it would have to simulate itself...)

Re: Can We Escape from Time?

#12

Post by dom0 »

WJW wrote: post #6
dom0 wrote: post #4

Earlier quoted context omitted.

This is a relatively common misconception. The location calculation in GPS is independent of any time dilation between the GPS receiver and the satellites (as long as the satellites have roughly equal dilation), because the receiver clock is derived from the satellites' signals. This is also the reason why you need at least four satellites for a 3D fix, and three for a 2D fix - you are always deriving an additional u…

Technically the fourth variable that a receiver solves for is the clock error in the receiver, not the actual time (though that then follows easily enough). The system of equations is only solvable because it is assumed that the clock error of the satellietes relative to each other is zero. I'm not convinced though that time dilation is the same for all the satellites, since they are not all in the same orbit. Since…

> According to [0] the clock drift due to relativistic effects would be over 45000 nanoseconds per day.

Between an uncorrected satellite and the receiver. This error is already removed through the fourth variable, only the average error of the satellites used for this remains (assuming perfect receiver etc.). So even if the satellites where not corrected the positioning error would not be "XY kilometers per day and climbing", the much smaller difference in time dilation between satellites would remain though.

Re: Can We Escape from Time?

#13

Post by baytrailcat »

Razengan wrote: post #11
brianberns wrote: post #5

"'There is no difference between Time and any of the three dimensions of Space except that our consciousness moves along it,' says the Traveller. That turned out, amazingly and counterintuitively, to be true. 'In surprisingly short order this notion would become part of the orthodoxy of theoretical physics,' says Gleick." What? Spacetime does contain four dimensions, but the whole reason that time travel is fiction,…

I wonder. If the universe is deterministic, and nothing is random, then Time could be thought of as a vector whose values encompass all the properties of everything in existence and the direction of changes in each of them. If we knew all the "rules" that govern those changes and could make a simulation that captured the current state of everything, we could traverse back and forth along that vector (but probably not…

This was a prevalent idea in physics till quantum mechanics burst into the scene. I don't remember where I saw it, this the most convincing argument I heard regarding simulating future: Our universe is actually the most efficient computer that can simulate the future with our physical laws. Meaning, at any given time, it is not actually executing a pre-determined program, it is busy computing the future.

Re: Can We Escape from Time?

#15

Post by bitL »

Are we capable of existing outside time?

Imagine instead of living in an [array of time-frames], moving in one direction, i.e. time, in a single frame only, like a snapshot (even with the possibility to observe the whole [array of time-frames] at once). Would you have any words to describe it? I think all our mental models would just collapse.

Re: Can We Escape from Time?

#16

Post by flatline »

imchillyb wrote: post #7

Picture Time as the surface of a pond. Events are a stone being dropped into or skipped along the surface of that pond. The waves produced by the event are viewable from all angles. The actual event -the stone drop- occurs only once. The event is immutable, even though the ripples persist and are measurable. We may eventually be able to view the ripples in more detail, and see past or future events. The events themse…

You could argue there is no event per se: it's all just ripples.

Re: Can We Escape from Time?

#17

Post by jacobolus »

brianberns wrote: post #5

"'There is no difference between Time and any of the three dimensions of Space except that our consciousness moves along it,' says the Traveller. That turned out, amazingly and counterintuitively, to be true. 'In surprisingly short order this notion would become part of the orthodoxy of theoretical physics,' says Gleick." What? Spacetime does contain four dimensions, but the whole reason that time travel is fiction,…

You’re right that “There is no difference between Time and any of the three dimensions of Space [...]” is kind of misleading, but it’s only half wrong.

The special relativity story is more nuanced. There’s no single “time direction”. Which direction in spacetime looks like “time” vs. a mix of “space” and “time” movements vs. “space” depends on your reference frame.

Every “faster-than-light velocity vector” can be considered the direction of “time” for some observer, just as every “slower-than-light velocity vector” can be considered a direction in “space” for some observer. A vector like “the vector difference between the position of the earth now and the moon half a second in the future” (by our measurement) is, for some other reference frame, a pure movement in time. In just the same way, “the vector difference between the position of the earth now and the moon two seconds in the future” is a pure distance in space indicating simultaneous-in-time events, for some other reference frame.

Or perhaps we should even say that the “reference frames” and a split between space and time dimensions are an abstract concept that we impose on top of the 4-dimensional spacetime. We can work out all of our physics in a 4-dimensional context without explicitly splitting “space” from “time”. https://en.wikipedia.org/wiki/Spacetime_algebra#Spacetime_sp...

In just the same way, if you have a two-dimensional Euclidean plane with no externally imposed markers on it, there’s no inherent notion of “up” or “left” – those depend entirely on what kind of reference you pick. Imposing some specific coordinates is sometimes useful for understanding the geometry and solving particular problems, but itÍ’s in some ways arbitrary.

Re: Can We Escape from Time?

#18

Post by seanp2k2 »

bitL wrote: post #15

Are we capable of existing outside time? Imagine instead of living in an [array of time-frames], moving in one direction, i.e. time, in a single frame only, like a snapshot (even with the possibility to observe the whole [array of time-frames] at once). Would you have any words to describe it? I think all our mental models would just collapse.

Considering you wouldn't be able to move or take in any new light, sound, etc it sounds pretty boring. Dark stillness.

Re: Can We Escape from Time?

#19

Post by scardine »

Razengan wrote: post #11
brianberns wrote: post #5

"'There is no difference between Time and any of the three dimensions of Space except that our consciousness moves along it,' says the Traveller. That turned out, amazingly and counterintuitively, to be true. 'In surprisingly short order this notion would become part of the orthodoxy of theoretical physics,' says Gleick." What? Spacetime does contain four dimensions, but the whole reason that time travel is fiction,…

I wonder. If the universe is deterministic, and nothing is random, then Time could be thought of as a vector whose values encompass all the properties of everything in existence and the direction of changes in each of them. If we knew all the "rules" that govern those changes and could make a simulation that captured the current state of everything, we could traverse back and forth along that vector (but probably not…

We can calculate things like if the moon is ever going to leave Earth's orbit and we can tell it was much closer to Earth in prehistoric times.

We can predict the future and recall the past, just not in a scale that is practical for our mundane lives. Personally, I think this is a humility lesson: in the grand scheme of things, the entire span of a human life is less than a tiny drop in the ocean of time.

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