What is time?

[Michael Mooney]

Originally Posted by Boerseun

The Earth is orbiting the sun. The sun is orbiting the galactic centre at a breakneck pace - something like once every 250 million years. Given the size of the galaxy, the sun is hammering along at a fair clip.

So are we orbiting the sun?

No.

We are orbiting the spot where the sun was, eight minutes ago.

Yet, that is currently "empty space" in the "universal now" that you propose.

There is no universal "now".

I agree with all the above but the last sentence.
I agreed, in the "Gravitation limit?" thread (or was it "Bang/Crunch Revisited"?) that the force of gravity travels at lightspeed, so that earth would remain in the same orbit for 8 minutes after the sun "magically" disappeared. Same point as your two preceding sentences.
We argued the last point (your last assertion) to death already. In the universal sense (i.e., not about signal delay, relativity or who can see what and when)... "IS" means present tense everywhere, not limited to specific loci.

This has nothing to do with where the sun was 8 minutes ago when it generated the force presently pulling on earth. Right now here is also right now where the sun presently IS regardless of the delay of gravity propagation between the two bodies.
Michael

[Michael Mooney]

We measure how long it takes events to happen and call it time. The reality is that events are always happening everywhere. As observers, we select certain *designated events* to measure the duration thereof. The reality is that earth is rotating, orbiting, etc. The measurement we call time is based on the duration of our monitoring of these events... whether "one complete rotation" as "24 hours, a day") or one of the three ways we measure "the year."

None of the above makes "time" into an entity. Yet we all find it meaningful and useful to say "It takes earth 24 hours of time to complete one rotation."
Michael

[Boerseun]

You're right, Michael, the topic has been debated to death.

It still doesn't mean that you're right, however. Nor me, for that matter.

The question "What is Time?" might simply be the wrong question.

It's kinda like asking "what is up?", or "what is left?", which cannot be answered without invoking their opposites. "Up" is the opposite of "down". Yes, but what is "down"? Well, "down" is the opposite of "up". Ad infinitum. You cannot describe a spatial direction without using another spacial direction. So if we say "time" is what elapses between two events, we're doing more of the same.

Everybody knows what "up" is, yet we do not ask that question because we think we know. Yet the question is one and the same.

Is time merely "motion"? No - because "motion" requires time beforehand. "Up" still requires "down" to be measured against.

I time merely the "flow" of entropy? No - because "flow", once again, requires time. So we're back at square one. "Left" still requires "right" to be defined, and "inside" requires "outside". Left, right, inside and outside are all spatial, and cannot be described without using other spatial points as reference. Time cannot be described without using time.

Time is fundamental. Asking "what" it is, implies that there is something even more fundamental, of which time is just en expression of that lower-level entity/entities interaction. And then we will ask what that lower-level entity is, and we will once again run into an endless discussion where we cannot describe that lower entity other than in terms of itself.

Asking what "time" is will result in an endless philosophical debate which cannot reach a conclusion other than the following:

Time is Time.

[Doctordick]

Originally Posted by Boerseun

The question "What is Time?" might simply be the wrong question.

Most would probably agree that “time” is a useful concept. What we need is to understand what we mean when we use the term.

Originally Posted by Boerseun

Time is fundamental. Asking "what" it is, implies that there is something even more fundamental, of which time is just en expression of that lower-level entity/entities interaction.

But you overlook the need for definition itself; at least within your mind. I know what I mean; but it certainly is not clear to me as to what all the rest of you mean and I personally doubt it is even clear in your minds.

Originally Posted by Boerseun

Asking what "time" is will result in an endless philosophical debate which cannot reach a conclusion other than the following:

Time is Time.

If it is a fundamental concept, you need to think about what purpose it serves. Try to look at “reality” as a collection of information. Look at it from a Godlike perspective: i.e., being all-knowing. Is time a necessary concept from that perspective? Why do “you” want to use time to describe your world-view?

I want to use time because what I know changes and I want to make sense of that experience. That is why I define time as I do: a parametric expression of that change. The past being what I know, the future being what I do not know and the present being a change in what I know. I can thus see what I know as a sequence of “remembered” presents. Sure, my “time” is not a “measurable” thing but, as an index, it gives order to my thoughts. Knowing what I mean allows me to analytically analyze the concept from an overtly rational perspective.

Have fun -- Dick

[Michael Mooney]

Boerseun (conclusion of post):

Asking what "time" is will result in an endless philosophical debate which cannot reach a conclusion other than the following:

Time is Time.

This leaves a great mystery in my mind... a question which still remains unanswered after all these debates in several related threads:

If I am wrong in my little essay on time above, (Post #584) and it is a malleable medium of some kind, which "dilates" etc. (as supposedly different than clocks keeping time differently at different velocities because of forces having acted on them differently to bring them to different velocities... differences in altitude, etc...))... what is it that is said to "dilate?"

What constitutes the "different time environment" at all different locations if the present (now) is not the present simultaneously everywhere?
Saying "time is time" is not an answer. Neither is "time is that which clocks measure."
If there were no humans or clocks, all parts of the cosmos from micro to macro scale would still be in motion. This galaxy would still revolve the same, with the same "event duration" for one revolution whether there were an earth or not to calibrate that great cycle in terms of the number of"earth orbits around the sun."

Closer to home, one earth revolution would take the same amount of "time" ( event duration) whether or not humans had ever evolved and invented all our various time-keepers.

There is no doubt in my mind that science is in error in the way "time" has been reified by the whole context of assumptions around relativity.
BTW...Did Einstein really say that if one could travel fast enough he could travel "through time? Would that create a "different time line" for each specific high speed journey? (What IS a "time line?")
Again, what is it that is supposed to change here and go in slow motion or faster other than the travelers themselves, perhaps their rate of metabolism, and their vehicle?
Michael

[modest]

Originally Posted by modest

If the universe were composed only of radiation then there would be no way to measure its wavelength.

~modest

Originally Posted by freeztar

I might be wrong, but I think Modest was implying that a universe consisting of only radiation would have no beings. Or, the beings in such a universe would *have* to be composed of only radiation.

Implying only that one ray of light cannot measure the wavelength of another. By definition, the wavelength of EMR is measured by an observer traveling less than c. If the whole universe is made of photons then who is going to hold the ruler? And... uh... what ruler?

~modest

[TheBigDog]

Originally Posted by modest

Implying only that one ray of light cannot measure the wavelength of another. By definition, the wavelength of EMR is measured by an observer traveling less than c. If the whole universe is made of photons then who is going to hold the ruler? And... uh... what ruler?

~modest

In a world made up only of photons the man with sunglasses is king. I don't know if that makes him the ruler.

[modest]

Originally Posted by TheBigDog

In a world made up only of photons the man with sunglasses is king. I don't know if that makes him the ruler.

"Particle man, Particle man... Is he a dot, or is he a speck? When he's underwater does he get wet, or does the water get him instead? Nobody knows, particle man."


I probably dismissed what LB was saying a bit too quick and out of hand:

Originally Posted by Little Bang

If the universe were composed only of radiation of one frequency then time would be the distance between two peaks or two troughs.

It could indeed be said that time is distance as it relates to light. Wavelength is the distance light travels during the time of one cycle. Time, then, relates to distance via the speed of light.

In relativity, the speed of light converts units of space to time in much the way it does between energy and mass. So, I think time being the distance of light makes some kind of sense.

~modest

[Boerseun]

Originally Posted by Michael Mooney

If I am wrong in my little essay on time above, (Post #584) and it is a malleable medium of some kind, which "dilates" etc. (as supposedly different than clocks keeping time differently at different velocities because of forces having acted on them differently to bring them to different velocities... differences in altitude, etc...))... what is it that is said to "dilate?"

Contraction also happens at relativistic speeds. But not for the observer travelling at that speed; only for other observers who are not in the same frame of reference, hence the term "relativity". For the observer travelling at relativistic speeds, everything would look perfectly normal. We are travelling at the speed of light relative to a photon, after all. The photon is standing perfectly still, as far as it's concerned, and we're streaming past it in a mass of cosmic rays, as far as it can tell about our world*. Coming back to my post about "up" and "down" being as fundamental as time itself, the same "mystery" as to what actually contracts, apply to space, as well.

It's fundamental. It's space that's contracting, and time that's dilating.

And both space and time can only be said to exist because it can be measured. It cannot be defined in any lower-level terms, because it's fundamental. If there was any "constituent" lower-level elements with which it could be defined, then that would've been fundamental.

Let's say that time could be defined as the interaction of foobles with nooblies. Then foobles and nooblies would be fundamental, and the title of this thread would be "what is nooblies?", with the same round-and-around arguing over what foobles and nooblies could possibly be.

* Not really - a photon, travelling at the speed of light, experiences no time at all - the origin and end of the universe is one and the same moment for a photon - but it illustrates the point.

[ldsoftwaresteve]

I don't think this subject can be beaten to death because it strikes at a very fundamental observation: we perceive something and it is so omnipresent that we automatically assume it exists.
If it does exist then our worldview will go in one direction and if it doesn't, it'll go in another.
Those two directions are just about as opposite as they can be.
Cause and effect will be different in each.