What is time?

[coldcreation]

Modest's claim is that earth's periods of rotation and orbit vary with the point from which they are "clocked."

 

Do you agree or not?

 

I'm sure CraigD or modest will answer your question. Until then I'd like to jump in.

 

Observers both at the top of a mountain and at sea level will have identical synchronized clocks, at the start of one earth rotation or orbit. The clock that is at sea level (deeper in the earth's gravity well) will run slower than the clock that is on top of a mountain (higher in altitude from the center of the gravitational mass of the earth).

 

It follows that as time elapses, say after one earth revolution, orbit or rotation, the clocks will show a time difference. The clock at sea level is slower in rate. The clock located at higher altitude runs faster.

 

Each observer makes her clock to be the running at the correct local rate. The observer on top of the mountain will notice, after one earth revolution, the other clock (at sea level) to run slower than the 'local' correct rate, and visa vera. Both observers will agree on the ratio of the difference.

 

Certainly the difference in the rate of the clocks is very small. But it is still present: a classic example of gravitational time dilation (predicted by GR and confirmed experimentally). See too Gravitational redshift

 

So modest is correct: earth's periods of rotation and orbit vary with the point from which they are clocked.

 

 

Along the same lines (philosophically) do you agree with Modest that the distances between bodies in space change with point of observation (different locations and velocities?)

This is clearly a form of subjective idealism, that reality is created by the observation, rather than being independent of same.

 

This would appear to be a classic time dilation problem. Nothing anthropomorphic or philosophical (or subjectively ideal) about it.

 

 

CC

[AnssiH]

Okay then!

 

I think distance and mass are equally circular as time.

 

The distance between two points in space (or two "locations") already supposes this things called "space" or "location" which then gets defined by the measurement of distance. Distance is a measurement. The actual thing "distance" is no more physical than time.

 

Likewise with mass. I don't know what a kilogram measures except to say that the measurement defines it.

 

More interesting, I think, is that to properly define any single one of them (mass, time, or distance) we need the other two. When we talk about the distance between two things, we are implicitly talking about the distance between two material points (i.e. mass). If there are no such material points then the measurement is not real and hence the thing we are claiming to measure is not real. Also with distance, implicit is the idea that both objects exist at the same time. Spatial distance alone is not capable of dealing with the distance between point A yesterday and point B tomorrow.

 

Likewise with time. Time is the 'distance' between two events which are collocated in space. Implicit in the measurement of time is some understanding of space... and of course these events which we are talking about need to be material points.

 

And, you can't measure mass without both space and time. If you push something and measure its acceleration then you need a good definition of both space and time.

 

I don't believe you can have a coherent understanding of mass, distance, or time individually without all three. All three are necessary (and sometimes sufficient) for mechanics.

 

Yes, thank you Modest. The interesting thing is that we do get the meaning of just about anything from the particular definitions surrounding those definitions, and the fact that they play together nicely doesn't really tell us anything about reality, it just tells us we have a self-coherent set of definitions in our hands, referring to particular circumstances in the data about reality.

 

The circularity of the definitions can certainly be found from there with some thought, but still many replies to this thread are simply stating the particular definitions of conventional physics, and talking about the logical consequences springing from those definitions.

 

When we are talking about the relativistic time relationships, it is important to note that it is, for a large part, the definitions of electromagnetism that are actually yielding those relativistic expectations for time measurements (as measured by the periodic cycles of electromagnetic apparatuses). Einstein pulled out his particular definitions (relativistic simultaneity and its consequences) from the definitions of electromagnetism (and their expression in symmetrical fashion between moving coordinate systems).

 

Time to open your thinking valves;

 

If you take "time" as what your electromagnetic apparatus displays, your explanation of how that apparatus works does follow Maxwell's equations. But those equations already assign a speed to the electromagnetic radiation. An "immaterial" speed* as in there is no way to measure it without that electromagnetic apparatus called "clock" (and knowing how it works, which depends on that speed we have yet to measure).

 

...and we have already exposed another circularity in the definitions...

 

What Einstein did was he expressed that speed from Maxwell's equations in invariant form between moving coordinate systems, because of circumstances already embedded in those definitions allowing/forcing him to do so. I wrote "allowing/forcing", because the definitions required some modification, so in that sense they were "forcing" him to do so. But on the other hand, there are other corrections one can make to the definitions to yield the same observables and same expectations regarding electromagnetic behaviour of objects (but don't imply the existence of relativistic spacetime or relativistic simultaneity etc.)

 

(Look up "moving magnet and conductor problem")

 

At any rate, the explanation called "electromagnetism" yields your expectations for what a clock measures, and careful application of those definitions across moving coordinate system yield the expectation that the electromagnetic apparatuses will count different cycle counts when in relative motion.

 

One type of conception of "time" ("evolution" or "change" giving meaning to "C") was already used in the underlying definitions (you need to be extra careful to not mix those two very different "time" concepts up), and that definition plays an important role in your expectations of observable clock cycles. (You must actually trace the expected dynamics of a clock, given your definitions)

 

*"Immaterial" much the same way as the definitions such as [imath]v_?[/imath] in DD's work, in that they are simply statements of relationships between other immaterial definitions, and the connection between the underlying definitions and the expectation of relativistic time relationships is explicitly exposed by his work.

 

-Anssi

[modest]

Yes, Anssi, I agree with what you say with caveats too small to mention. I might respond in detail when I have time.

 

Michael:

 

Let's start slow. Does the velocity of a particle change value from the point by which it is considered? Please avoid giving me a long reply on why velocity is different from time. Just... can you agree with the above?

 

~modest

[lemit]

Could I be allowed a little aside? Whenever I see the title of this thread in the sidebar, I read it as "What time is it?" akin to the "What are you listening to right now?" thread. It makes sense to me then that there are so many responses, since it gives people an easy way to pad their post count.

 

Oh, by the way, it's 12:10 a.m. MDT here right now.

 

Oops! 12:11.

 

--lemit

[Michael Mooney]

Modest:

Let's start slow. Does the velocity of a particle change value from the point by which it is considered? ...

 

Starting slow is good. I will first distinguish between apparent velocity and actual velocity. What we observe, even the image of our hand in front of our face,has signal delay, as light brings the image to the eye(and travels via the optic nerve signal to the visual cortex, where "I see my hand.")

So, as for the velocity of a particle, its apparent velocity will change with with different points from which it is considered, but its actual velocity will not.

So, applying this principle to my inquiry/challenge in previous posts:

 

Likewise "clocking" one earth revolution will give different apparent elapsed times at different altitudes, as you say, (as clocks "tick" slower or faster) but the actual duration of one earth rev will not change because of these differences in measurement.

OK so far?

Michael

[Michael Mooney]

coldcreation:

So modest is correct: earth's periods of rotation and orbit vary with the point from which they are clocked.

 

So, if folks with clocks at different altitudes are getting different readings for "elapsed time" for one earth rotation (which of course they are).... you must see the absurdity here.

 

See my last post to Modest. Apparent elapsed time varies, but earth certainly doesn't actually speed up and slow down in rate of rotation just because our clocks... well... "clock" a rotation differently.

Do you agree?

Michael

[freeztar]

So, if folks with clocks at different altitudes are getting different readings for "elapsed time" for one earth rotation (which of course they are).... you must see the absurdity here.

 

It is absurd, I agree. It goes against any intuitive ideas we have about how things work. Yet, it happens and it's all relative.

See my last post to Modest. Apparent elapsed time varies, but earth certainly doesn't actually speed up and slow down in rate of rotation just because our clocks... well... "clock" a rotation differently.

Do you agree?

The Earth does not physically speed up or slow down due to our clocks. It is more accurate to say that time, for certain events, has a different duration depending on where, in the gravity well, the measurements are taken from.

 

There's no preferred reference frame. The Earth's rotation will always measure the same duration each and every time it is measured from the same place (reference frame). Move to a different altitude (different location in the gravity well), and it will always measure the same from that reference frame. But neither will agree with each other, ever.

 

If we assign an 'absolute time' (preferred reference frame) to, say, sea level on Earth, then we can use equations to determine how time is different in different reference frames (as compared to our preferred reference frame).

 

It seems absurd, I agree. But it's one of the many strange things about our universe.

[coldcreation]

 

So modest is correct: earth's periods of rotation and orbit vary with the point from which they are clocked.

So, if folks with clocks at different altitudes are getting different readings for "elapsed time" for one earth rotation (which of course they are).... you must see the absurdity here.

 

No absurdity there.

 

 

See my last post to Modest. Apparent elapsed time varies, but earth certainly doesn't actually speed up and slow down in rate of rotation just because our clocks... well... "clock" a rotation differently.

Do you agree?

Michael

 

It appears that your stance has changed little form your previous posts, this one in particular.

 

The one change I do see is that, now, it seems you accept the basis that clocks will show differences in time depending on altitude; though it is not for the reasons you posted above, regarding the delay in light travel time due to c).

 

It is due to the verifiable fact that we live in a curved spacetime continuum. The deeper one find herself immersed within the gravitational well, the slower will tick her clock (preferably a NIST-F1 Cesium Fountain Atomic Clock), when compared to an identical clock located at higher altitude.

 

So, to answer your question again, there is no absurdity here. The difference in time recorded at differing altitudes is confirmation that modest is correct when he writes: "earth's periods of rotation and orbit vary with the point from which they are clocked."

 

It is obviously not because mountains rotate around the globe fast than the oceans. Nor is it because, as you entail, the earth speeds up and slows down in rate of rotation because our clocks "clock" a rotation differently.

 

It is because the answer to the question of how long it takes to complete one orbit depends on the location in the field where the clock is situated in relation to a standard fixed reference frame.

 

There is no God's eye view.

 

That would be absurd. :)

 

 

CC

[Michael Mooney]

freeztar:

The Earth does not physically speed up or slow down due to our clocks.

Thank you! This is precisely my point in all of this.

 

It is more accurate to say that time, for certain events, has a different duration depending on where, in the gravity well, the measurements are taken from.

 

So, when you say this, what is it it that you are referring to as "time" having a different duration besides the fact that clocks "keep time" differently depending on their elevation and the different gravitational effects on them?

I have always agreed to the above fact. But Modest and others still assert that earth's rate of rotation (and orbit) changes with differences in measurement... which is still obviously absurd.

 

There's no preferred reference frame. The Earth's rotation will always measure the same duration each and every time it is measured from the same place (reference frame). Move to a different altitude (different location in the gravity well), and it will always measure the same from that reference frame. But neither will agree with each other, ever.

 

Please understand that when I say that earth's periods of rotation and orbit do not change with different points of observation, I am saying that those periods stay the same regardless of different clock read-outs, and that "staying the same" is independent of measurement, i.e., beyond "frame of reference"... not claiming a "preferred frame of reference."

 

If we assign an 'absolute time' (preferred reference frame) to, say, sea level on Earth, then we can use equations to determine how time is different in different reference frames (as compared to our preferred reference frame).

 

This is exactly what I told Modest many months ago as we debated the differences in clocks "ticking rate" at different altitudes.

I suggested that a reasonable standard might be our best clocks at sea level on the equator (as Earth does bulge at the equator... not a perfect sphere, of course.)

BTW, my argument has never been with those equations. They, in fact make the corrections between different points of measurement.

 

Likewise the distances between bodies in space. As Pyrotex once said, aliens approaching our solar system at near lightspeed would need those equations to find the *actual distances* between bodies in our system (as well published on many astronomy websites... giving the near and far distances between sun and all planets as per their out-of round orbits.)

Modest claims those distances change with each different point and its velocity of observation... which, again, is absurd.

 

Michael

[Michael Mooney]

coldcreation:

The difference in time recorded at differing altitudes is confirmation that modest is correct when he writes: "earth's periods of rotation and orbit vary with the point from which they are clocked."

 

Compare this absurd claim with freeztar's reasonable assertion (and my total agreement) that:

The Earth does not physically speed up or slow down due to our clocks.

 

If Modest had said that our clocks keep time differently while clocking earth's periods of rotation and orbit depending on differences in points of observation, then there would be no argument here.

Do you see the difference?

Michael

[coldcreation]

The difference in time recorded at differing altitudes is confirmation that modest is correct when he writes: "earth's periods of rotation and orbit vary with the point from which they are clocked."

 

Compare this absurd claim with freeztar's reasonable assertion (and my total agreement) that:

The Earth does not physically speed up or slow down due to our clocks.

 

I don't see the claim made by modest to be absurd, since it is in complete agreement with empirical observations.

 

And obviously the Earth does not physically speed up or slow down due to our clocks.

 

That would be absurd.:)

 

 

If Modest had said that our clocks keep time differently while clocking earth's periods of rotation and orbit depending on differences in points of observation, then there would be no argument here.

Do you see the difference?

Michael

 

What you write here is just a different way of saying the same thing as modest.

 

 

CC

[Michael Mooney]

coldcreation,

Modest claims that that earth's periods of rotation and orbit vary with the point from which they are "clocked."

 

Freeztar, myself, and common sense say:

The Earth does not physically speed up or slow down due to our clocks.

You can't have it both ways. Pick one of the above.

Michael

[freeztar]

coldcreation,

Modest claims that that earth's periods of rotation and orbit vary with the point from which they are "clocked."

 

Freeztar, myself, and common sense say:

 

You can't have it both ways. Pick one of the above.

 

You *can* have it both ways, and indeed it is.

 

To understand this, you will have to abandon your ideas about "absolute time" and learn about Special Relativity.

[Michael Mooney]

You *can* have it both ways, and indeed it is.

 

To understand this, you will have to abandon your ideas about "absolute time" and learn about Special Relativity.

 

OK, I'll bite. How can both of the following statements be true?:

A:

Earth's periods of rotation and orbit vary with the point from which they are "clocked."

B:

"The Earth does not physically speed up or slow down due to our clocks."

 

I've said dozens of times that I do understand relativity, both general and special, and understand that the resulting equations provide a vast improvement in the accuracy of all that relativity encompasses without the invention/riefication of either space or time or both together (as an actual bendable, dilating, malleable medium.)

 

Maybe if you understood Doctordicks equations better (I don't, btw) his perspective on relativity from a *universal* "frame of reference" and a time-transcending presentism (my "universal now") you would understand better my perspective/philosophy as well.

(Obviously his math and physics are much more credible here than my mere "philosophy.")

To reiterate, my recently stated philosophy in this regard is:

 

" ...that the cosmos and all its parts have an existence and a dynamic including rates of rotation/orbit, trajectories and velocities of movement independent of homosapien science and its measurements."

You may delete "velocities" from the above without disturbing the sense of the statement.

 

Michael

[Erasmus00]

I've said dozens of times that I do understand relativity, both general and special, and understand that the resulting equations...

 

Michael, saying something over and over again does not make it true. You have made it very clear by your many statements that you have almost no understanding of the basic assumptions of either theory, and how to move from those assumptions to concrete predictions. In short, you would fail the basic tests on special relativity I give to college freshmen.

 

As a psychologist, you must be familiar with the Dunning-Kruger effect, I suggest that perhaps you don't actually know enough to evaluate your understanding of the theory. Consider that literally everyone on this board you have talked with has suggested your understanding of relativity is lacking- how many people will suggest this before you take it seriously?

[CraigD]

So I have shared my philosophy of science as per "time."

Enough already.

Michael

While I disagree with many to most of the conclusion about objective reality I perceive Michael to draw from his philosophy, I share and echo his “enough already” sentiment.

 

When I started this thread over 4 years ago with an opening post closing

What’s do you believe time is, or is not, and why?

with the word “believe”, a signal word inviting the sharing of “what you believe, but can’t prove”, I was hoping to compile a catalog of peoples’ informal, intuitive beliefs about time. Being a science forum, I assumed many to most of our intuitions would reconcile well in a mathematically formal way with experimentally validated observation, but a good catalog of beliefs would need to include intuitions for which this is not true.

 

This old thread is huge. :) Taking a short novel to measure 30,000 words, its 927 posts to date have the words of about 5 of them, with at best the same ease of reading. It’s drifted beyond recognition as a catalog of ideas. A moderatorly splitting up of it is years overdue. I’ll undertake the herculean task with my less than herculean personal resources soon, splitting its many subdiscussions, including the recent “*various*: Michael, you just don’t get it / Michael: *various*, you all just don’t get it” one, into separate threads.

 

Throughout the last month of few of this thread, dominated largely by the discussion (I’m aware some might argue against my use of the word) between Michael and various, I’ve been impressed with it as a strong illustration of what Snow was describing in his 1959 “Two Cultures” lecture, which included

A good many times I have been present at gatherings of people who, by the standards of the traditional culture, are thought highly educated and who have with considerable gusto been expressing their incredulity at the illiteracy of scientists. Once or twice I have been provoked and have asked the company how many of them could describe the Second Law of Thermodynamics. The response was cold: it was also negative. Yet I was asking something which is the scientific equivalent of:

Have you read a work of Shakespeare's?

 

I now believe that if I had asked an even simpler question — such as, What do you mean by mass, or acceleration, which is the scientific equivalent of saying,

Can you read?

— not more than one in ten of the highly educated would have felt that I was speaking the same language. So the great edifice of modern physics goes up, and the majority of the cleverest people in the western world have about as much insight into it as their neolithic ancestors would have had.

Though I may be presumptuous in thinking our humble forum comparable to Snow’s “gatherings of the highly educated/cleverest people in the western world”, I see echoes of what he’s describing in the following posts from myself and Michael:

I must admit to a belief like that expressed in Snow’s The Two Cultures, that people who can’t perform at least rudimentary, formal calculations of modern physics can’t, in a practical, meaningful sense, understand them. In much the way I’m skeptical of someone who tells me “I know how to juggle” until I’ve actually seen them keep a few balls in the air, I’ll be skeptical of your [Michael Mooney’s] claim of understanding both general and special relativity until I’ve seen you do some calculating tricks with them.

 

Without the ability to perform these “tricks”, and their prerequisite geometric, arithmetic, and algebraic tricks, I’m uncertain to what extent you’re able to comprehend dichotomies such as the one I tried to present in post #838, Michael.

Philosophy deals very well with concepts, while math is the technical form of logic which helps to bring a premise or assumption to a logical conclusion. You [freeztar?] pull the math-superiority card on me without even realizing what I just said. Math is not prior and superior to the concepts which it quantifies. And I don't think you even realize that you subscribe to the subjective idealism philosophy when you "dis" mine out of hand.

It’s clear to me from these that Michael and I are speaking to one another across the culture gap Snow described and cautioned against. I’m quite, emotionally-intuitively comfortable with dismissing anyone who can’t do college freshman level mathematical physics “tricks” as someone incapable of understanding physical reality – as clear a pulling of “the math-superiority card” as any, I think - while Michael appears to me just as comfortable prioritizing (if I understand and paraphrase him accurately) philosophy as that which generates and deals with concepts, and the mathematical formalism I prize so highly as a sort of glorified proofreading.

 

The reason I think – and think Snow would agree – that the activity of natural philosophy needs mathematical thought is that such though not only grants its thinker access to formal techniques for checking ideas and bringing them to logical conclusions, but also influences and dynamically interacts with her philosophical intuition. It is, I believe, an important rudiment, without which the thinker is severely, and unnecessarily, impaired.

[modest]

Doctordick puts it well,

 

...in particular, they tend to disregard mathematics as a tool useful to abstract thought. Exact statements in English are not easy to make. As a language, mathematics is the most exact language available; it is widely understood with minimal probability of misinterpretation. All one has to do is think about it a little.

 

~modest :)