Zones of backward time

[petrushka.googol]

Is it possible theoretically to have zones of backward time in the universe?

This would still obey the laws of cause and effect where a more complex state would resolve into a simpler one.

eg. On such a planet a human would be born old and die young. Cause and effect would still apply although defying commonly accepted norms and conventions. Entropy would still increase and people would still be eccentric.

Is such a scenario possible in realty?

 

 

[swansont]

How would you transition from a zone of forward time to backward time?

[Strange]

Slowly?

[Phi for All]

In a timely manner?

[Greg H.]

More importantly, if cause still precedes effect and entropy still increases, what are you using to define time as "backwards"?

[Endercreeper01]

It is impossible to have backwards time in any part of the universe (according to our current understanding of the universe).

In special relativity, time dilates by the equation [latex]\tau = t \sqrt{1-\frac{v^2}{c^2}}[/latex]. In order for [latex]\tau [/latex] to be negative, [latex]\sqrt{1-\frac{v^2}{c^2}}[/latex] must be negative also. Because the square root refers to the positive value in the equation, it can't be negative.

This also applies to general relativity. Time also dilates as a result of gravity. Time is dilated by the equation [latex]\tau = t \sqrt{g_{00}}[/latex]. In the Schwarzschild solution, [latex]g_{00}=1-\frac{2GM}{rc^2}[/latex], so it becomes [latex]\tau = t \sqrt{1-\frac{2GM}{rc^2}}[/latex] for a spherical, non-rotating, and uncharged mass.

Even if [latex]R_s=r[/latex] or [latex]r>R_s[/latex], there is no way to make the equation have negative time.

[Greg H.]

@Endercreeper:

Not to drift off topic, and ignoring the impossibility of travalling at the speed of light, but what would it mean if, in the following equation v = c?

[math]\tau = t \sqrt{1-\frac{v^2}{c^2}}[/math]

 

 

[Strange]

@Endercreeper:

 

Not to drift off topic, and ignoring the impossibility of travalling at the speed of light, but what would it mean if, in the following equation v = c?

 

The result is invalid. Which is reasonable because you cannot travel at the speed of light, and light doesn't form a valid frame of reference.

[Endy0816]

My present thinking is that anything time reversed still appears to us as moving forwards.

 

Been kind of thinking that we may be able to look at a black hole as acting as a double temporal mirror depending on the properties of hawking radiation. Can't look into it much though until we get some hard evidence of hawking radiation in the first place.

 

In any case I think proof or any zones are essentially hidden from our view. Literally or in the sense that our interpretation of events will be forward biased.

Edited January 22, 2014 by Endy0816

[michel123456]

It is impossible to have backwards time in any part of the universe (according to our current understanding of the universe).

In special relativity, time dilates by the equation [latex]\tau = t \sqrt{1-\frac{v^2}{c^2}}[/latex]. In order for [latex]\tau [/latex] to be negative, [latex]\sqrt{1-\frac{v^2}{c^2}}[/latex] must be negative also. Because the square root refers to the positive value in the equation, it can't be negative.

This also applies to general relativity. Time also dilates as a result of gravity. Time is dilated by the equation [latex]\tau = t \sqrt{g_{00}}[/latex]. In the Schwarzschild solution, [latex]g_{00}=1-\frac{2GM}{rc^2}[/latex], so it becomes [latex]\tau = t \sqrt{1-\frac{2GM}{rc^2}}[/latex] for a spherical, non-rotating, and uncharged mass.

Even if [latex]R_s=r[/latex] or [latex]r>R_s[/latex], there is no way to make the equation have negative time.

That looks like circular thinking to me.

In mathematics, a square root has 2 values, positive and negative.

 

Quoted from Wiki:

 

In mathematics, a square root of a number a is a number y such that y² = a, in other words, a number y whose square (the result of multiplying the number by itself, or y × y) is a.^[1] For example, 4 and −4 are square roots of 16 because 4² = (−4)² = 16.

 

[Endercreeper01]

 

Not to drift off topic, and ignoring the impossibility of travalling at the speed of light, but what would it mean if, in the following equation v = c?

 

[math]\tau = t \sqrt{1-\frac{v^2}{c^2}}[/math]

 

 

When [LATEX]v=c[/latex], time stops relative to an outside observer. Relative to the object, it would experience no time dilation. Because everything else would appear to be moving at c relative to the object, time would stop for everything else relative to the object. But this is just using the equation. If something really were to travel at c, we don't know what would happen to the time passed for it relative to an observer.

 

That looks like circular thinking to me.

 

 

In the equation, the principle square root is used. The principle square root is the non negative value of the square root. This is because the observer will see the object traveling forwards in time if [latex]t[/latex] is positive. They can't see it traveling both forwards and backwards in time.

Edited January 23, 2014 by Endercreeper01

[swansont]

It is impossible to have backwards time in any part of the universe (according to our current understanding of the universe).

In special relativity, time dilates by the equation [latex]\tau = t \sqrt{1-\frac{v^2}{c^2}}[/latex]. In order for [latex]\tau [/latex] to be negative, [latex]\sqrt{1-\frac{v^2}{c^2}}[/latex] must be negative also.

Or t is negative. i.e. "backwards" time. The equations you refer to really apply to time intervals, and the initial value is assumed to be zero. I don't think they a priori exclude negative time.

[Endercreeper01]

Or t is negative. i.e. "backwards" time. The equations you refer to really apply to time intervals, and the initial value is assumed to be zero. I don't think they a priori exclude negative time.

Yes, but why would there be a negative time zone? Coordinate time always moves into the future, and those equations are the only ways we know of capable to distort time.

Edited January 27, 2014 by Endercreeper01

[swansont]

Yes, but why would there be a negative time zone? Coordinate time always moves into the future, and those equations are the only ways we know of capable to distort time.

 

That would be related to the question I posed in my first post in this thread. But would it, if there were such a thing as negative time?

[michel123456]

How would you transition from a zone of forward time to backward time?

In a Minkowski diagram, the zone of positive time is what we are currently observing, IOW the positive is the down part of the diagram: the Past.

 

If this is correct, then the negative part is the upper part of the diagram: the Future.(which is not observable)

 

And if the above is correct, then we are currently living in the Present at the edge of the zone between positive and negative time.

 

If the the 2 "ifs" are correct.

 

-------------------------------------

Another view at it consists in switching the diagram upside down. If the Past switches with the Future, and the arrow of time stays upright, the diagram shows time reversal.

Edited February 5, 2014 by michel123456

[Endercreeper01]

In a Minkowski diagram, the zone of positive time is what we are currently observing, IOW the positive is the down part of the diagram: the Past.

 

If this is correct, then the negative part is the upper part of the diagram: the Future.(which is not observable)

 

And if the above is correct, then we are currently living in the Present at the edge of the zone between positive and negative time.

 

If the the 2 "ifs" are correct.

 

-------------------------------------

Another view at it consists in switching the diagram upside down. If the Past switches with the Future, and the arrow of time stays upright, the diagram shows time reversal.

Yes, but why would this happen? Why would time need to go backwards?

Edited February 5, 2014 by Endercreeper01

[swansont]

In a Minkowski diagram, the zone of positive time is what we are currently observing, IOW the positive is the down part of the diagram: the Past.

 

If this is correct, then the negative part is the upper part of the diagram: the Future.(which is not observable)

 

And if the above is correct, then we are currently living in the Present at the edge of the zone between positive and negative time.

 

If the the 2 "ifs" are correct.

 

-------------------------------------

Another view at it consists in switching the diagram upside down. If the Past switches with the Future, and the arrow of time stays upright, the diagram shows time reversal.

 

There is no negative/backward time in a standard Minkowski diagram