What is time?

[ldsoftwaresteve]

AnsiH

"Well, I would say that's a bit careless statement as well; whether one assign the energy to particle's path or particle itself, it has still got exactly the energy one simply decides it has got (which inertial frame one happens to choose for plotting the path in)."

Excellent point. Kind of brings doubt into the whole idea of energy as an existent, doesn't it?
I wonder how widespread the practice of this sort of mental projection really is? I suppose the fear that such thoughts evoke depends upon how essential these concepts are to one's worldview.
Why do I find such things so incredibly beautiful?
Perhaps the beauty is in the nature that could contemplate them.
Or perhaps because it's like another shoe has dropped and we're moving toward a more comprehensive understanding that doesn't have pillars made of smoke.

[Doctordick]

Originally Posted by modest

Does your decision about which inertial frame to use actually somehow change the kinetic energy of a particle?

You are kind of overlooking a very important issue. You cannot simply “change the kinetic energy of a particle” by deciding to use a different inertial frame. When you change your frame of reference, you change the apparent kinetic energy of every particle in the universe. One should not be sloppy about such issues.

Have fun -- Dick

[modest]

Originally Posted by AnssiH

Well, I would say that's a bit careless statement as well; whether one assign the energy to particle's path or particle itself, it has still got exactly the energy one simply decides it has got (which inertial frame one happens to choose for plotting the path in).

[...snip]

I may need to take a step back and explain...

Originally Posted by AnssiH

it never was something that ontologically existed inside the spaceship somehow

You are correct.

If you place a 3D box at the center of the room you're in and step back from it, it will appear a certain way to you. As you change your position in the room the box will change appearance. Your view of the box is 2 dimensional—you see it as a 2 dimensional form. Your choice of where to stand in the room and which specific 2D projection of the box you get is arbitrary and there are essentially an infinite number of 2D projections you can get.

This is a geometric effect. The box does *not* change in ontological form as you view it differently. Rather, if you force a 2 dimensional view of a three dimensional object then changing the position from which you view it will change the two dimensional form without changing the 3 dimensional object.

Kinetic energy in modern (spacetime) relativity is similar. It is a 3 dimensional concept in what is described as a 4 dimensional world. If you force your view of a particle to be 3 dimensional then changing the frame of reference from which you view it will change the energy of the particle. This is a geometric effect same as the box above. The particle does *not* change ontologically as the frame of reference from which it is considered changes. The invariant mass stays the same as the energy and momentum components (like time and space components) of the geometry describing the particle change.

A google search for "four velocity" or "four momentum" might explain in more detail.

~modest

[AnssiH]

Originally Posted by ldsoftwaresteve

Excellent point. Kind of brings doubt into the whole idea of energy as an existent, doesn't it?

To me, it is yet another demonstration of how people confuse the human made definitions with reality itself. (Like any good constructivist would tell you )

I see people making that mistake all the time, but most people just don't seem to have the ability or will to question their beliefs about reality...

I wonder how widespread the practice of this sort of mental projection really is? I suppose the fear that such thoughts evoke depends upon how essential these concepts are to one's worldview.

Maybe so. I am often amazed by how people who keep repeating how relativity needs to be understood exactly in terms of how everything is relative, still consistently communicate issues in terms of "things moving" rather than "coordinate systems moving"... And I see the same people saying things that imply halfway newtonian ideas to time evolution, while they are supposed to stick with the definitions of relativity... And I see the same people saying in one context that "such and such relativistic situation is impossible", just to refer to exactly the same situation in another context and suddenly say it is "made possible by relativity".

Like think about how faster than C travel of information leads to violation of relativity (with spacetime interpretation anyway), and on the other hand spacetime construction allowing "wormholes" as valid solutions... If you had wormholes, that is exactly the same as bringing information through from one place to another, faster than light.

Yet if you bring "faster than C" to the table, it's automatically thought of as "false". If you bring wormholes, it's suddenly all okay.

It's all a bit thoughtless if you ask me.

Why do I find such things so incredibly beautiful?
Perhaps the beauty is in the nature that could contemplate them.
Or perhaps because it's like another shoe has dropped and we're moving toward a more comprehensive understanding that doesn't have pillars made of smoke.

Well I for one would like to see people drop their faith a little and look at the logical consequences of their definitions little bit closer...

Oh, and;

Originally Posted by TheBigDog

...what is the practical purpose of clarifying our understanding of time?

For me it would be to solidify a truth, a formula, that would then be applied to understanding other concepts that still allude us.

Now that hits the nail in the head...

Note also that "clarifying our understanding of time" is not about "understanding time ontologically correctly", but rather about stripping the undefendable aspects out from our conception of "time". I.e. being exactly and entirely self-coherent in our ideas of it.

Reaching self-coherence, as you might expect, does resolve all kinds of things that presently elude us. But people don't seem to be very receptive when the resolution to those self-conflicting things requires a transformation to concepts they have great faith in. Would require too much painful thinking with no guarantee of success, I guess.

-Anssi

[AnssiH]

Originally Posted by modest

Kinetic energy in modern (spacetime) relativity is similar. It is a 3 dimensional concept in what is described as a 4 dimensional world. If you force your view of a particle to be 3 dimensional then changing the frame of reference from which you view it will change the energy of the particle. This is a geometric effect same as the box above. The particle does *not* change ontologically as the frame of reference from which it is considered changes. The invariant mass stays the same as the energy and momentum components (like time and space components) of the geometry describing the particle change.

Like I said;
"Believe me, I do understand how people look at relativistic spacetime as an explanation exactly to that conundrum with "parameters that are dependent on our choice of inertial frame."

And;
"What I was trying to point out earlier was that there are some very good underlying reasons as to why our definition of "length" and "time" behave that way, and it's got absolutely nothing to do with the existence of a hypothetical entity called relativistic spacetime (nor ontologically real "relative simultaneity")."

I.e. relativistic spacetime works as an explanation, but it is by no means the only possible explanation, and furthermore it is resting entirely on human made definitions, not touching the raw data that we are explaining at all (=ANY raw data is well explained via definitions that lead to a model of "relativistic spacetime")

It would do good for people to understand those "underlying reasons", to loosen up little bit of that faith on their ontological ideas.

-Anssi

[modest]

Originally Posted by Doctordick

You cannot simply “change the kinetic energy of a particle” by deciding to use a different inertial frame. When you change your frame of reference, you change the apparent kinetic energy of every particle in the universe.

Agreed.

~modest

[Little Bang]

Thank you Modest. You have made a brilliant post which has given me some very interesting points to ponder. A possible lead to time and charge.

[ldsoftwaresteve]

Originally Posted by TheBigDog

Time is used as a frame of reference for all those things, that I can see, but how is it the cause?

Bill

Beautiful point Bill.

That is the crux of the whole issue. On the one hand, if you believe that time is an existent, then it becomes the 'cause' of all change and that pretty much covers the whole enchilada.

On the other hand, if it is an internal concept we project into existence, then it doesn't exist and cannot be the cause of change. What then, is?

From a practical point of view, it would seem that our ability to command nature will be directly proportional to the accuracy of our model.

The current model of physics is loaded with concepts that have no more ontological reality than a rainbow. Yet they are used and we create and build and comprehend with them. Imagine what we could do with an accurate model.

[Michael Mooney]

Originally Posted by ldsoftwaresteve

Beautiful point Bill.

That is the crux of the whole issue. On the one hand, if you believe that time is an existent, then it becomes the 'cause' of all change and that pretty much covers the whole enchilada.

On the other hand, if it is an internal concept we project into existence, then it doesn't exist and cannot be the cause of change. What then, is?

From a practical point of view, it would seem that our ability to command nature will be directly proportional to the accuracy of our model.

The current model of physics is loaded with concepts that have no more ontological reality than a rainbow. Yet they are used and we create and build and comprehend with them. Imagine what we could do with an accurate model.

I agree ('cept that rainbows are actual refraction of light into the full spectrum, while time is.... yes... simply the ongoing now... for whatever measured duration.)
Though this is a "philosophy of science" section, the "good relativists" here refuse to even consider what time is (if anything) in and of "itself"... beyond the constructs/concepts "in our minds"... as event duration per se regardless of measurements based on specific "frames of reference."(Ref: my last post.)

It seems to me that subjective idealism is the prevailing philosophy upon which this whole discussion is based, except our "camp", addressing the ontology of time.

Incidentally, concerning a trivial point... Bill, re your statement:

Just a not Mike, but it was the sadistic captain in Cool Hand Luke who said, "What we've got here is... failure to communicate. Some men you just can't reach." He was saying it because Luke would not obey his rules.

...
The above turned out to be the "punchline" of the whole movie, as Luke parroted it back to "Boss" right before Boss shot him dead.

Sooo...I've kind of adopted it as the theme of this "communication" (or lack thereof) on "time" here.
Michael

[ldsoftwaresteve]

Michael, I agree with you too. I was using a 'rainbow' as in, "Hey Michael, let's go slide down that rainbow over there!"

AnsiH used it too, although he immediately wished he hadn't - perhaps because a rainbow is sensed and references something external, whereas time and energy are pure abstractions and directly reference nothing external to ourselves.

This is so new that the only analogy I can give for the discussion is that we have just entered a room with very few footprints in the dust. And it is dark and we can't see clearly yet because we don't really understand the key that opened the door - other than the lock was made up mostly of fear.

The hope is that over time... we'll come to illuminate the objects in it.

What was + X = What is. What is + X = what next.

What we 'see' = what we sense + what we invent. It isn't always easy to separate the two, especially if the thing that we 'see' seems to be part of change, that is, part of everything we sense.

Time is the placeholder of change. If it doesn't exist, what is driving change? How do we get from 'what is' to 'what next'?