What is time?

[Theory5]

I simply think of time as man's perception of linear events.

Or man's linear perception of events...

[Little Bang]

Time brings up another interesting question. The equation F = Ma where F is given in the newton, kg . m/sec^2. Since the acceleration of any particle, whether it's inertial or gravitational, produces time dilation then the variability of the sec^2 might explain gravitational and inertial forces?

[modest]

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

 

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

 

~modest

[TheBigDog]

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

 

~modest

For beings that can only sense radiation this is the reality of the universe.

[Johndude969]

In my opinion time is a dimension of space. What we refer to when we say time is in fact a set of co-ordinates of the dimension. It is also my belief that the dimensions of time and space are fused. For this reason a set of co-ordinates are not just a place but a time as well. In that sense travel through space also translates as travel through time. The existance of time as a planar dimension that runns parallell to our own and is at the same time fused exists for the main purpose that events that have already happened cannot be changed as this could cause a tear in the fabric of Time-Space. As such the only reason for time to exist is to prevent cataclysmic (sorry if my spelling is poor) tears in reality forming. That is what time is in my opinion.

[Michael Mooney]

I guess my edited version of 'what is time?' belongs in this thread rather than in the "Is Time an Abstract Idea?" thread, as it's author is quite a bit more "abstract" about his/her philosophy of time than I.

Sorry 'bout the redundancy, but this version is an improvement over my last version above in this thread:

Quoting myself as per my usual violation of protocol:

 

Time is the *concept/measure* of event duration.

This can be any "event" from a designated period of cesium's radioactive decay (as calibrated in atomic clocks) to Earth's "great precession" cycle of around 26,000 years.

Most familiar "timed events" of course are Earth's period of orbit and rotation, and fractions thereof, down to seconds and very small fractions of a second.

 

However, none of these periods of "time" are ontologically real as entities or a malleable medium of any kind. They are, as you said, merely concepts or measurements of designated events, beginning and ending with the observer's 'clicks of the stopwatch.'

 

So, in truth, *now,* the present *is* always present, not sliced into units of time in the real world/cosmos.

The future is not yet real and present and the past is not still real and present, and there is no "time" between future and past. Time is the convention of event duration from one designated now to another.

 

So, "spans of time", as above are as real as we make them. There is no cosmic counter clicking at every complete earth rotation, orbit, etc. Yet we can "be on time" to work by common consensus on the *convention, time,* and we can plug in "time" as a component of velocity and calculate and execute a round trip to the moon or speak in terms of "light minutes or years" as measures of distance.

 

It is also conventional to call "time" the fourth dimension added to the obvious spacial three which describe volume. Then we can avoid having two airplanes at the same coordinates in air-space at the same time. A very useful convention.

But "it" doesn't expand and contract as an actual entity of any kind, i.e., not "real" in that sense, or in the sense that each location has its own "time environment." "It" is always, perpetually *NOW everywhere.* (Same "it" as in "It is raining..." no agent "it" making rain happen.)

 

Last time for the above, I promise.

Michael

[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".

[freeztar]

For beings that can only sense radiation this is the reality of the universe.

 

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.

 

In any case, they would (or not) have the same quandary with time. Assuming SR holds in a radiation-only universe.

[ldsoftwaresteve]

I like Theory5's response about time being a perception of linear events.

That puts 'time' into the context of a mental creation which is what I think it is.

We automatically assume that all of our perceptions indicate that something exists and I think that is a weak assumption.

We have memory. That allows us to perceive events and perform internal comparisons of those events. I see there a strong possibility for making a subtle mistake with profound consequences on our worldviews: we project time into existence because we perceive it internally. That is the argument for Time being simply an abstraction without any existential properties.

I am not attacking the efficacy of using the concept. I am simply saying that we cannot presume qualities or attributes of time as if it were something that actually exists.

[freeztar]

I like Theory5's response about time being a perception of linear events.

That puts 'time' into the context of a mental creation which is what I think it is.

We automatically assume that all of our perceptions indicate that something exists and I think that is a weak assumption.

We have memory. That allows us to perceive events and perform internal comparisons of those events. I see there a strong possibility for making a subtle mistake with profound consequences on our worldviews: we project time into existence because we perceive it internally. That is the argument for Time being simply an abstraction without any existential properties.

I am not attacking the efficacy of using the concept. I am simply saying that we cannot presume qualities or attributes of time as if it were something that actually exists.

 

If time doesn't exist, then it would follow logically that it could not be measured. Yet, this is not the case. We can measure time, regardless of our perceptions (Relativity helped seal (or open)the case for this).

 

I understand the quandry. We can't use our measurement of time as an essential quality of time. With that, I agree. I can measure the diameter of a basketball, but that tells me nothing about the game of basketball.

 

We are limited, conceptually. We have clocks and I can tell you that it's 9 AM, but I can't tell you why. I can measure the diameter of the ball at any given point, but I can't tell you a thing about basketball. Does that mean the game is not real?

[Little Bang]

Time is relative to the observers frame of reference which we all know. A clock in another moving frame of reference slows with respect to our observer. This goes back to post #580. If we had a one kg block setting on a frictionless surface and apply a force of 1kg.m/sec^2 it will accelerate at 1m/sec^2. The only way to increase this acceleration is to increase the applied force OR slow the observer's clock. Isn't this exactly what happens in a gravity well ?

[TheBigDog]

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.

 

In any case, they would (or not) have the same quandary with time. Assuming SR holds in a radiation-only universe.

Yeah, I was just thinking about how we even realize what the universe is composed of. Imagine you were a thermometer. All you know is the current temperature. You have no memory. To you the whole universe is just the current temperature. You have no ability to understand cause and effect or make abstract connections because all you can perceive is the current temperature. No wind, no rain, no snow, no vacuum of space, no shade, just the current temperature. That is what inspired the response.

 

To a thermometer the universe is just heat and has no time.

 

Bill

[Michael Mooney]

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]

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.

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. :Nurse:

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? :hyper:

 

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. :eek:

 

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