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What force makes time go "forwards"?

As "now" evolves, how is yesterday manifested? Where is yesterday at? What form does the past assume?

If yesterday is irretrievable, where has all the energy before "now" gone?

Can time be accelerating as observed from extra dimensions, and yet appear constant from within spacetime?

Could dark energy be a manifestation of time, past and future, within which information is retrievable to the present?

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Well your callsign certainly matches your post lol. "abstract". no force makes time go forward.

time is simply a rate of change or duration nothing more

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why does everything seem to only go in the same direction wrt time?

If time is a rate of change, then something that cannot change has no time.

if time is relative between object and observer, does this mean we can never observe something which never changes?

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Time with a direction is a misnomer. It is not really going left or right etc. It simply means that if we mathematically treat time as a vector. The future is considered a forward direction. ie we can never goto the past.

Don't confuse this with a true direction.

Its simply meant time goes from present to future not present to past.

You can't really stop time nothing lasts forever no matter how long it seems to stay in the same state. The universe itself isn't infinite. It will end eventually.

Edited by Mordred
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What force makes time go "forwards"?

As "now" evolves, how is yesterday manifested? Where is yesterday at? What form does the past assume?

If yesterday is irretrievable, where has all the energy before "now" gone?

Can time be accelerating as observed from extra dimensions, and yet appear constant from within spacetime?

Could dark energy be a manifestation of time, past and future, within which information is retrievable to the present?

These questions probably belong in the Philosophy section where there are several other similar threads. Be prepared for it to ramble on for months with no answers.

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These questions probably belong in the Philosophy section where there are several other similar threads. Be prepared for it to ramble on for months with no answers.

Not really confident on that, not enough to move this thread. I'll let one of the more experienced Moderators make that choice lol. I'm only a sort of Mod with limited powers lol. Resident experts can move threads when appropriate.

Edited by Mordred
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These questions probably belong in the Philosophy section where there are several other similar threads. Be prepared for it to ramble on for months with no answers.

My first impression was similar to yours; however, as Mordred here beautifully demonstrated, it is possible to give answers that are solid, non-controversial.

Despite the disagreements between him and me about some aspects of "time" on the philosophy forum, I agree with his statements here above. I think that's very useful and constructive.

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Is there any thing that can be considered to be unchanging?

Suppose we are somehow present at the death of the observable universe has anything remained "as it always was" ?

Whereas 1+2 no longer =3 ?

Will mathematics cease to apply incrementally as the conditions it described end?

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What force makes time go "forwards"?

As "now" evolves, how is yesterday manifested? Where is yesterday at? What form does the past assume?

If yesterday is irretrievable, where has all the energy before "now" gone?

Can time be accelerating as observed from extra dimensions, and yet appear constant from within spacetime?

Could dark energy be a manifestation of time, past and future, within which information is retrievable to the present?

Time is relative.

Here below my understanding:

The concepts of Future & Past in time are similar to Front & Back in space. If you make a U-turn, then what was Back becomes Front, and what was Front becomes Back. Because Front & Back are relative to you, the observer.

If you translate this concept of Front & Back in time, then it may be (maybe) that the Past and Future are also relative. For that to be true, one must delete the apparent differences between Future and Past. It means that the Past should stop to be "frozen", stop to "exist" and become the same fuzzy as the Future is. If impossible then yes, the question remains: what is that thing that makes us go from the Past to the Future?

Edited by michel123456
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Time with a direction is a misnomer. It is not really going left or right etc. It simply means that if we mathematically treat time as a vector. The future is considered a forward direction. ie we can never goto the past.

Don't confuse this with a true direction.

Its simply meant time goes from present to future not present to past. [..]

I'll elaborate a little on this. Time doesn't have a true direction, thus it's also not a real vector. For example if you have a car, it has a counter of miles or km traveled. That distance can only increase - even if you travel back home. The concept of "time" is similarly cumulative.

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exactly. Excellent elaberation. Thank you for the above commentary. Those philosophy threads I enjoyed. Its nice getting into a well rounded debate. It also served to remind me of the issues others have in understanding spacetime. So in that regard I too found those threads useful.

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!

Moderator Note

This was posted in physics, so please discuss accepted physics. Not speculation, pet theories, or philosophy. If you want to discuss something other than mainstream physics, open a thread in the appropriate area

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point taken on the philosophy discussion.

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exactly. Excellent elaberation. Thank you for the above commentary. Those philosophy threads I enjoyed. Its nice getting into a well rounded debate. It also served to remind me of the issues others have in understanding spacetime. So in that regard I too found those threads useful.

Let me try and be precise with a question about the math. If spacetime is a 4D manifold, with time being one of the four, then how is it mathematically possible that time, being one of these dimensions, isn't oriented in any particular fashion in relation to the other dimensions?

In other words, if it's hyperbolic, or orthogonal, or whatever mathematical description is used, how can these descriptions not be relative to something? And if they are relative, then how does that relativity mathematically avoid the inclusion of direction? Isn't direction at the very core of relativity? Doesn't simultaneity require a direction?

At this point I disagree with the notion that time isn't oriented in any direction. I could be convinced otherwise if I were able to understand the mathematical argument better.

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Let me try and be precise with a question about the math. If spacetime is a 4D manifold, with time being one of the four, then how is it mathematically possible that time, being one of these dimensions, isn't oriented in any particular fashion in relation to the other dimensions?

In other words, if it's hyperbolic, or orthogonal, or whatever mathematical description is used, how can these descriptions not be relative to something? And if they are relative, then how does that relativity mathematically avoid the inclusion of direction? Isn't direction at the very core of relativity? Doesn't simultaneity require a direction?

At this point I disagree with the notion that time isn't oriented in any direction. I could be convinced otherwise if I were able to understand the mathematical argument better.

Because time is not directly one dimension of the 4 dimensional spacetime manifold.

The fourth dimension is time multiplied by a physical constant, with suitable dimensions to make the product another length.

We call this constant c and it can be deduced from several different routes in Physics.

Edited by studiot
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Let me try and be precise with a question about the math. If spacetime is a 4D manifold, with time being one of the four, then how is it mathematically possible that time, being one of these dimensions, isn't oriented in any particular fashion in relation to the other dimensions?

In other words, if it's hyperbolic, or orthogonal, or whatever mathematical description is used, how can these descriptions not be relative to something? And if they are relative, then how does that relativity mathematically avoid the inclusion of direction? Isn't direction at the very core of relativity? Doesn't simultaneity require a direction?

At this point I disagree with the notion that time isn't oriented in any direction. I could be convinced otherwise if I were able to understand the mathematical argument better.

I think that it's rather well explained in Einstein's appendix on Minkowski space.

Thus the "time" axis ct is perpendicular on the spatial axes purely for mathematical purpose (eq.12).

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I think that it's rather well explained in Einstein's appendix on Minkowski space.

From the above link I find this quite telling: From a "happening" in three-dimensional space, physics becomes, as it were, an "existence" in the four-dimensional "world."

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I think that it's rather well explained in Einstein's appendix on Minkowski space.

Thus the "time" axis ct is perpendicular on the spatial axes purely for mathematical purpose (eq.12).

The way that I understand these words, it's paradoxical to say that something is perpendicular and yet has no direction. What does that mean when we say that it has no direction but it is also perpendicular? Doesn't seem right. What creates this paradox?

Because time is not directly one dimension of the 4 dimensional spacetime manifold.

The fourth dimension is time multiplied by a physical constant, with suitable dimensions to make the product another length.

We call this constant c and it can be deduced from several different routes in Physics.

And the multiplication is performed why, exactly? If time were coincident with one of the suitable dimensions then we would add, wouldn't we? Multiplication implies a specific orientation doesn't it?

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From the above link I find this quite telling: From a "happening" in three-dimensional space, physics becomes, as it were, an "existence" in the four-dimensional "world."

I fully agree; note that it's essential to not overlook the clarifying words "as it were".

The way that I understand these words, it's paradoxical to say that something is perpendicular and yet has no direction. What does that mean when we say that it has no direction but it is also perpendicular? Doesn't seem right. What creates this paradox? [..]

The only paradox I can perceive here is a confusion between mathematics and physics. Here we discussed a graphical presentation of equation 12.

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The way that I understand these words, it's paradoxical to say that something is perpendicular and yet has no direction. What does that mean when we say that it has no direction but it is also perpendicular? Doesn't seem right. What creates this paradox?

And the multiplication is performed why, exactly? If time were coincident with one of the suitable dimensions then we would add, wouldn't we? Multiplication implies a specific orientation doesn't it?

You need to read up on the difference in meaning between the words independent and perpendicular.

No multiplication does not imply direction, nor is it contained in the definition of multiplication.

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...nor is it contained in the definition of multiplication.

Interesting. It sounds as if you're arguing that when we say that something is 4 high and 2 wide and we can multiply the two together to get 8 that it's simply some coincidence that the two directions are also perpendicular. I don't understand why anyone would make that argument, but there it is. It sounds incorrect to me.

The only paradox I can perceive here is a confusion between mathematics and physics. Here we discussed a graphical presentation of equation 12.

If math and physics have different definitions for direction and multiplication, or different interpretations of a graph, then yes, I am definitely confused.

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Interesting. It sounds as if you're arguing that when we say that something is 4 high and 2 wide and we can multiply the two together to get 8 that it's simply some coincidence that the two directions are also perpendicular. I don't understand why anyone would make that argument, but there it is. It sounds incorrect to me.

If math and physics have different definitions for direction and multiplication, or different interpretations of a graph, then yes, I am definitely confused.

But space has no direction either. Objects moving in space can have a direction, but inherently there is no direction in space.

If objects can move following different directions in space that is because space is 3D. If time is 1D, then the only possible direction is along the 1D.

The question is simply why does time "flow" along this 1D line in a particular direction and why is it impossible to make a U-turn in time.

Edited by michel123456
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I fully agree; note that it's essential to not overlook the clarifying words "as it were".

Opposed to..."as it is"...?

* Just Tim and me having our own little private chat *

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I'll elaborate a little on this. Time doesn't have a true direction, thus it's also not a real vector. For example if you have a car, it has a counter of miles or km traveled. That distance can only increase - even if you travel back home. The concept of "time" is similarly cumulative.

Right, distance is always positive. Time is also always positive. And gravitation always attractive. There is a "direction" in the Universe.

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But space has no direction either. Objects moving in space can have a direction, but inherently there is no direction in space.

If objects can move following different directions in space that is because space is 3D. If time is 1D, then the only possible direction is along the 1D.

The question is simply why does time "flow" along this 1D line in a particular direction and why is it impossible to make a U-turn in time.

This question seems to be answered by the definition of direction itself. It's always relative to some other direction. The question you're asking is more along the lines of the philosophical question of whether or not time would exist without space.

If the answer to that philosophical question is yes, then sure, I can understand how time could avoid having a direction. But if time is considered to be part of a manifold then it must have a direction, mustn't it? I don't see any alternative, physically or mathematically,.

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