Basic understanding of time

[michel123456]

 

Then what it means is you can't rotate 180º on the time axis.

Well, If for a different observer what is space for him is time to me, it looks like a rotation where, when rotated, time becomes space.

 

I don't think that's a good way to look at it. We can always define an origin at some point in space, and in time. No matter where it is, we can always plot a position and time of a certain event that occured. Suppose that event occured right now. Any other event that we observe will be observed with a positive time separation from this current event. However in terms of space the location could vary in either positive or negative (or be the same) as the current event. Therefore it's not that you are defining negative distance, it is a negative position, which is compared to a certain origin which is completely possible, however it's not possible in terms of time. What petrushka.gogol said before makes sense, however us as living beings see, and consider direction of increasing entropy to be positive, and you can make an argument that it's the same as saying that for us time is always running in the positive direction. It would be really cool to do the whole back to the future thing though

Show me negative space. There is no such a thing.

[swansont]

Well, If for a different observer what is space for him is time to me, it looks like a rotation where, when rotated, time becomes space.

Any evidence that this happens, anywhere (or anywhen, as the case may be)?

[knyazik]

Well, If for a different observer what is space for him is time to me, it looks like a rotation where, when rotated, time becomes space.

Show me negative space. There is no such a thing.

 

not negative space. negative location. and I if you just tell me where your origin is, I will definitely show it to you!

[michel123456]

Any evidence that this happens, anywhere (or anywhen, as the case may be)?

If you take a spacetime diagram, X axis is space & Y axis is time. The observer is at the intersection of the 2 axes. An object in constant motion is represented by a diagonal line, the velocity is represented by the angle of the line. A rotation of the line represents a change in the state of motion (acceleration). For any other observer in different state of motion the time & space axis are tilted (rotated). Which means that what time is for an observer becomes a part of space for another, and vice-versa.

 

http://upload.wikimedia.org/wikipedia/commons/thumb/d/db/Minkowski_lightcone_lorentztransform.svg/588px-Minkowski_lightcone_lorentztransform.svg.png

 

So, when 2 observers are in different state of motion, for them the time (and space) axis are rotated. When they change their state of motation then rotation takes place.

 

not negative space. negative location. and I if you just tell me where your origin is, I will definitely show it to you!

You understand negative as it was negative direction. But you can have space without thinking about direction. Simply "space". I don;t know anything like "negative space"

 

For example, in hypothetical "negative space", one could also have a bunch of directions (and positions)

Edited November 1, 2014 by michel123456

[swansont]

If you take a spacetime diagram, X axis is space & Y axis is time. The observer is at the intersection of the 2 axes. An object in constant motion is represented by a diagonal line, the velocity is represented by the angle of the line. A rotation of the line represents a change in the state of motion (acceleration). For any other observer in different state of motion the time & space axis are tilted (rotated). Which means that what time is for an observer becomes a part of space for another, and vice-versa.

 

http://upload.wikimedia.org/wikipedia/commons/thumb/d/db/Minkowski_lightcone_lorentztransform.svg/588px-Minkowski_lightcone_lorentztransform.svg.png

 

So, when 2 observers are in different state of motion, for them the time (and space) axis are rotated. When they change their state of motation then rotation takes place.

 

 

That's a rotation of axes, not time becoming space.

[elfmotat]

 

That's a rotation of axes, not time becoming space.

 

I think he means that in a Lorentz transformation x's and t's are 'mixed' together to get the transformed coordinates. In the same way that a coordinate rotation will 'mix' x's and y's to get the rotated coordinates.

[michel123456]

 

I think he means that in a Lorentz transformation x's and t's are 'mixed' together to get the transformed coordinates. In the same way that a coordinate rotation will 'mix' x's and y's to get the rotated coordinates.

Yes, the Lorentz transformation is a kind of rotation in spacetime.

 

What i understand (maybe I am wrong on this) is that (a part of) what is space for an observer is (a part of) time for another.

 

What i also understand is that the rotation is such that space & time coincide for something traveling at Speed Of Light.

And that the axis of time & space cannot switch.

Edited November 2, 2014 by michel123456

[knyazik]

Yes, the Lorentz transformation is a kind of rotation in spacetime.

 

What i understand (maybe I am wrong on this) is that (a part of) what is space for an observer is (a part of) time for another.

 

What i also understand is that the rotation is such that space & time coincide for something traveling at Speed Of Light.

And that the axis of time & space cannot switch.

 

Is there a fundamental reason in the way that we describe space time that we cannot switch space axis and time axis? If we for instance talk about a space momentum 6D space, switching the axis, or rotating by 90 degrees is allowed, why can't we use similar logic to switch space and time axis?

[michel123456]

 

Is there a fundamental reason in the way that we describe space time that we cannot switch space axis and time axis? If we for instance talk about a space momentum 6D space, switching the axis, or rotating by 90 degrees is allowed, why can't we use similar logic to switch space and time axis?

Good question.

As far as I know, in all theories with more than 4 dimensions, all supplementary dimensions are spatial. It is believed that there is only 1 temporal dimension. That is because there are some fundamental differences between Space & Time.

[swansont]

 

If we for instance talk about a space momentum 6D space, switching the axis

 

 

We do? In what context?

[elfmotat]

 

 

We do? In what context?

 

Phase space of a single particle I'm guessing.

[petrushka.googol]

Good question.

As far as I know, in all theories with more than 4 dimensions, all supplementary dimensions are spatial. It is believed that there is only 1 temporal dimension. That is because there are some fundamental differences between Space & Time.

 

My own simple visualization is thus :

 

the 4th dimension is coupled collectively to the 3 dimensions in space (not to an individual axis) and translation in this space is experienced as time. Time cannot be visualization as another plane but should be thought of as a curved space that mimics the lower orders of magnitude. (in this case 3 dimensional space).

[knyazik]

 

My own simple visualization is thus :

 

the 4th dimension is coupled collectively to the 3 dimensions in space (not to an individual axis) and translation in this space is experienced as time. Time cannot be visualization as another plane but should be thought of as a curved space that mimics the lower orders of magnitude. (in this case 3 dimensional space).

 

So let's take this to a simple case where space is only in one dimension x, so we have a 2D space of (x,t). In that case do you mean to say that i cannot think of some sort of a profile (whether linear or curved) in the XT space, but instead a whole bunch of points in X dimension that are just taken at different times? Am I thinking about the "curved space" in a wrong way? Thank you for your contribution.

[petrushka.googol]

 

So let's take this to a simple case where space is only in one dimension x, so we have a 2D space of (x,t). In that case do you mean to say that i cannot think of some sort of a profile (whether linear or curved) in the XT space, but instead a whole bunch of points in X dimension that are just taken at different times? Am I thinking about the "curved space" in a wrong way? Thank you for your contribution.

 

Time according to me is notional. As a control experiment consider a cubical box placed at an origin at some time T₀. Even if the box has not translated in space it may translate in time because the observer sees it that way. Space is real and time is virtual. That is why we speak of space-time. Even a stationary object translates in the time axis even if it does not move in space. The converse of course is not true. According to me time is the driving virtual vector dimension and space the following scalar dimension. Just my thoughts running riot....

[knyazik]

 

Time according to me is notional. As a control experiment consider a cubical box placed at an origin at some time T₀. Even if the box has not translated in space it may translate in time because the observer sees it that way. Space is real and time is virtual. That is why we speak of space-time. Even a stationary object translates in the time axis even if it does not move in space. The converse of course is not true. According to me time is the driving virtual vector dimension and space the following scalar dimension. Just my thoughts running riot....

So let me see if I understand. What you have is a virtual constant vector, which has associated space-like vectors at each one of its values? Is that an accurate description of what you mean?

[petrushka.googol]

So let me see if I understand. What you have is a virtual constant vector, which has associated space-like vectors at each one of its values? Is that an accurate description of what you mean?

 

Yes..

[knyazik]

 

Yes..

 

I see, but what is the fundamental principle from not viewing it from the other point of view, where your virtual vector is constant and is space, and time is the associated vector?

[petrushka.googol]

 

I see, but what is the fundamental principle from not viewing it from the other point of view, where your virtual vector is constant and is space, and time is the associated vector?

 

 

Time by itself has no meaning. Space does. If i say you have an object that looks like a box you can be sure what to expect. If I say I saw an object at T = 3 units it means very little, except that the object was in motion for 3 s. This could be 3 s from any origin that you choose to select. Space on the other hand always completely describes the nature of the object irrespective of where you choose the reference axes. A box at rest or a box in motion is always a box. Just contemplate the same.

[knyazik]

 

 

Time by itself has no meaning. Space does. If i say you have an object that looks like a box you can be sure what to expect. If I say I saw an object at T = 3 units it means very little, except that the object was in motion for 3 s. This could be 3 s from any origin that you choose to select. Space on the other hand always completely describes the nature of the object irrespective of where you choose the reference axes. A box at rest or a box in motion is always a box. Just contemplate the same.

 

Well you can think of something as having a size in terms of time. All it means is that for a certain period of time there indeed was matter at a certain position. So a box at rest will also look like a box at rest from this point of view. What do you think?

[petrushka.googol]

 

Well you can think of something as having a size in terms of time. All it means is that for a certain period of time there indeed was matter at a certain position. So a box at rest will also look like a box at rest from this point of view. What do you think?

 

Fully endorse this...space and time though complementary are totally different when viewed independantly. That is my viewpoint.

[knyazik]

I think the bottom line is our understanding of time, space, etc. is all limited by our observations. Based on what we observe we came with a model that differantiates time and space, and yet at the same time allows us to use the time-space 4 vector. 150 years ago no one would have considered arguments that we are making today, limited by one's experiences, and the whole idea that time space is a function of one's velocity was pretty unorthodox. 200 years before that, you would most likely be burned for such reasoning. I really wonder how well we will understand the subject in another 100-150 years. Perhaps at that point our ancestors will read arguments on blogs like this and laugh at how primitive our thought pattern was...

[petrushka.googol]

I think the bottom line is our understanding of time, space, etc. is all limited by our observations. Based on what we observe we came with a model that differantiates time and space, and yet at the same time allows us to use the time-space 4 vector. 150 years ago no one would have considered arguments that we are making today, limited by one's experiences, and the whole idea that time space is a function of one's velocity was pretty unorthodox. 200 years before that, you would most likely be burned for such reasoning. I really wonder how well we will understand the subject in another 100-150 years. Perhaps at that point our ancestors will read arguments on blogs like this and laugh at how primitive our thought pattern was...

 

I infer that you are an optimist .....

[knyazik]

 

I infer that you are an optimist .....

 

I sure am, and I really hope that pursuit of science especially pure science will yield results that are unimaginable to us today, but would be second nature to future generations. Oh yeah, and if someone created perpetual motion, or a time machine, even better, lol! (I know that its impossible)