29 Dec 15
Originally posted by DeepThoughtYou cannot divorce time and space.
No, this isn't correct. In Einstein's universe time is a dimension, it has the same status as the space-like dimensions. If we choose some Cartesian coordinates (this is in special relativity so I'm neglecting curvature for this post) then we can rotate the coordinates to get new ones. Similarly different inertial reference frames involve a transforma ...[text shortened]... s. So time is not just a property of something else, it is one of the dimensions of space-time.
They cannot exist without one another.
30 Dec 15
Originally posted by whodeyWhy could there not be a universe without time, just space-like dimensions? Although it sounds like nothing happens there can be a non-trivial quantum theory built on it. Saying "This is the case" does not entail the sentence "This must be the case.".
You cannot divorce time and space.
They cannot exist without one another.
30 Dec 15
Originally posted by DeepThoughtI cannot imagine space without time, can you?
Why could there not be a universe without time, just space-like dimensions? Although it sounds like nothing happens there can be a non-trivial quantum theory built on it. Saying "This is the case" does not entail the sentence "This must be the case.".
If so, do tell.
30 Dec 15
5 edits
Originally posted by whodeyDo you believe that what we cannot imagine, as opposed to merely conceive, cannot be?
I cannot imagine space without time, can you?
If so, ask yourself; what is the premise of that belief?
It is partly because of this very common baseless belief that many people erroneously still reject quantum mechanics and relativity despite the overwhelming evidence (and partly because many people cannot accept there are people much smarter than them who understand things they don't)
30 Dec 15
Originally posted by humyAll I'm saying is that I have no point of reference for a dimension outside space and time.
Do you believe that what we cannot imagine, as opposed to merely conceive, cannot be?
If so, ask yourself; what is the premise of that belief?
It is partly because of this very common baseless belief that many people erroneously still reject quantum mechanics and relativity despite the overwhelming evidence (and partly because many people cannot accept there are people much smarter than them who understand things they don't)
I've said before that I believe such dimensions exist even though I don't understand them.
But to say that there is space without time seems more unlikely since I have familiarity with both of them.
30 Dec 15
Originally posted by whodeyIn the actual world there are at least three space-like dimensions and one time-like one. There are possible worlds where there is no time-like dimension. For example, one can build perfectly mathematically consistent theories of two-dimensional quantum gravity with two space like dimensions and no time-like one (one space-like and one time-like dimension is also possible). When I say possible world I mean in the sense of Kripke, they do not necessarily exist, but are required to be, well, possible.
All I'm saying is that I have no point of reference for a dimension outside space and time.
I've said before that I believe such dimensions exist even though I don't understand them.
But to say that there is space without time seems more unlikely since I have familiarity with both of them.
There's an additional problem here because in Physics there are two times. One is the dimension we've been talking about, the other is time as a sequence of events which mark irreversible changes in state. Imagine a clockwork clock, the governor (the rocker thing at the top of the pendulum that prevents the spring unwinding all at once) advances the clock mechanism a little each time the pendulum gets to the end point of one of its swings. So the time on the clock depends on this sequence of irreversible events. We can think of the spring unwinding as being like entropy increasing, so the hands on the clock only go clockwise because the spring unwinds and we don't get back to earlier states. We have a sequence of irreversible events (unless someone winds up the clock). Einstein's theory has no explanation as to why we can only move one way in time. This clock analogy shows that the view of time as a sequence of irreversible events explains why we only perceive time changing in one direction.
The difficulty is that it is unclear how these two views of time are related to each other, in physics and philosophy this is called the Problem of Time.
31 Dec 15
1 edit
Originally posted by DeepThoughtSaying that space can exist devoid of time is speculative, as where the Problem of Time is proven phenomenon which proves that time in the known universe is not a constant. It can be warped in many different ways. It would stand to reason then, that it might be possible to stop it altogether.
In the actual world there are at least three space-like dimensions and one time-like one. There are possible worlds where there is no time-like dimension. For example, one can build perfectly mathematically consistent theories of two-dimensional quantum gravity with two space like dimensions and no time-like one (one space-like and one time-like dimens ...[text shortened]... of time are related to each other, in physics and philosophy this is called the Problem of Time.
How do you feel about going back into time?
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31 Dec 15
1 edit
Originally posted by joe shmoHence if you started a clock simultaneously in time frame one and time frame 2 ( a time parallel to frame 1), you would have the time compression component in frame 1 while accelerating to c, then a component perpendicular to frame one where you end in frame 2's past the length of frame 2 rest time minus frame 1's compression component?
Since V is confined to be less than c, if we remove the restraint and allow for imaginary values V>c could it mean that time is a complex plane, where going faster than c means a movement through time orthoganlly to a parallel time?
01 Jan 16
Originally posted by joe shmoA time vector? The trick would be actually doing that. Any suggestions?
Hence if you started a clock simultaneously in time frame one and time frame 2 ( a time parallel to frame 1), you would have the time compression component in frame 1 while accelerating to c, then a component perpendicular to frame one where you end in frame 2's past the length of frame 2 rest time minus frame 1's compression component?
01 Jan 16
Originally posted by sonhouseA time-like vector is a vector which points in a time like direction. Any velocity vector of anything physical points in a time-like direction. A time vector ought to be a purely time-like vector, so all you have to do is stay still!
A time vector? The trick would be actually doing that. Any suggestions?
01 Jan 16
Originally posted by whodeyTime is a dimension it doesn't move - we move through it. For reasons to do with causality I do not think it is possible to turn back the clock.
Saying that space can exist devoid of time is speculative, as where the Problem of Time is proven phenomenon which proves that time in the known universe is not a constant. It can be warped in many different ways. It would stand to reason then, that it might be possible to stop it altogether.
How do you feel about going back into time?
01 Jan 16
Originally posted by DeepThoughtOr more correctly, turning back the clock would not reverse causality (the clock is causality) so you would not remember the future and it would be indistinguishable from turning forward the clock. The flow of time is an illusion and the clock isn't really moving.
Time is a dimension it doesn't move - we move through it. For reasons to do with causality I do not think it is possible to turn back the clock.
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01 Jan 16
Originally posted by sonhouseYes, a time vector in a (at least) 2D complex plane containing infinite time continuum's ( time paths,lines,points...however you want to look at it.) The vector consists of a Real component for all (V<c), and an Imaginary component for all (V>=c). It doesn't seem like reverse causality would be an issue in this form of time travel (time travel between parallel time lines), as you are not strictly traveling backwards in your time line, but by exceeding or equaling "c" you end up in the past of another (parallel) time continuum by virtue of the Lorentz Transformation.
A time vector? The trick would be actually doing that. Any suggestions?
I thought of it last night, and is only based on mathematics (not physics strictly speaking), but we do know that generally the interpreted reality of the physical world lags behind the abstraction of the mathematical world. So what is the deal Physicists, please (very simply) tell me how I am a buffoon for conceiving of such a notion in theory as I have said, or in application as sonhouse has implied.