time intuitively defined relatively?

[kriminal99]

Thought experiment: You stare at a clock, and nothing else is moving, nothing changing, no internal clocks either (or imagine all you have is your internal clock). The clock ticks once, and then again but the second time a longer amount of time passes before it ticks. Would you have any way to tell that the second tick took longer before it happened? How could you?

 

Whats the point? The subconsious definition of time is something like the difference between events. The smallest possible unit of time is the smallest amount of time in between two events. The smallest possible unit of time recognizable by a human depends on the physical nature of the mind (refresh rate? frequency?)

[Johnny5]

Thought experiment: You stare at a clock' date=' and nothing else is moving, nothing changing, no internal clocks either (or imagine all you have is your internal clock). The clock ticks once, and then again but the second time a longer amount of time passes before it ticks. Would you have any way to tell that the second tick took longer before it happened? How could you?

[/quote']

 

The only way, is to have another clock to compare to.

 

And for a clock to function the way we need it to, the amount of actual time between any two consecutive ticks must be equal.

 

The italicized part there, has to be incorporated into the definition of clock.

 

Or, in your example here, you are a comparing a bad clock to a good clock.

 

So a "good clock" is one which ticks out equal amounts of time, in successives ticks, a bad one ticks out different amounts of time sometimes, between successive ticks.

 

Mathematically, you could say that the 'rest rate' of the clock has to be a constant.

 

Denote the rest rate of a clock by G.

 

Then, dG/dt=0

 

Where the derivative is to be taken in an inertial reference frame in which the clock is at rest.

 

As far as human perception of time that is a whole different story. For most of us, eight hours a day, we have no perception of time whatsoever. It's called sleep. Yet time still passes, regardless of our perception of how much of it has passed... or even deeper whether or not we are even aware of it passing.

 

However, obviously there is something we are all endowed with, which allows us to measure time... a clock.

 

It seems to tick fairly regularly to me.

 

Nice post by the way.

[swansont]

Actually, a clock can still be useful if (using Johnny's terminology) dG/dt is a constant.

[Kygron]

Actually, a clock can still be useful if (using Johnny's terminology) dG/dt is a constant.

 

Or any known non-random function, I bet. It's just that the more complex the function, the harder it is to make use of the clock.

[Kygron]

Whats the point?

 

I think the point of clocks is that they're easy to make, and that once syncronized (with known deviations, etc.), they generally stay syncronized.

 

This gives you a simple way to make a measurement, assuming you want to make a measurement in the first place. Measurements help define the world, so the more, simple, forms available, the easier it is to recognize what's happening.

 

On a practical note, knowing when the sun will rise it usefull if you're planning on doing something that you need light for!

[swansont]

I think the point of clocks is that they're easy to make' date=' and that once syncronized (with known deviations, etc.), they generally stay syncronized.

[/quote']

 

Good ones, especially really good ones, aren't easy to make, and it's impossible for them to stay synchronized.

 

The best you can do for a clock is random (aka white) frequency noise. The integral of this is random-walk noise in the phase (i.e. the time). So two synchronized clocks will, at best, do a random-walk away from each other. You always have to resynchronize; it's just a matter of how often.

[Johnny5]

The best you can do for a clock is random (aka white) frequency noise. The integral of this is random-walk noise in the phase (i.e. the time). So two synchronized clocks will' date=' at best, do a random-walk away from each other. You always have to resynchronize; it's just a matter of how often.[/quote']

 

This last part here, on Gaussian white noise, the random walk problem covered in probability theory, Markov chains...

 

Were those mathematical things developed for the specific problem of clock synchronization, or did the mathematics develop first, and then got applied to the problem of clock synchronization later?

 

Regards

[swansont]

This last part here' date=' on Gaussian white noise, the random walk problem covered in probability theory, Markov chains...

 

Were those mathematical things developed for the specific problem of clock synchronization, or did the mathematics develop first, and then got applied to the problem of clock synchronization later?

 

Regards[/quote']

 

They were developed before, I believe.

[kriminal99]

heheh Uh I think I didn't get my point across really well...

 

Its kind of hard to put into words but my point is that the subconsious definition of time is "difference between observable events" We have an internal clock so if we don't see anything going on outside of us (and I mean absolutely nothing changing) we can still gauge time by this. But the point is time would have no meaning if nothing was changing anyways.

[Johnny5]

But the point is time would have no meaning if nothing was changing anyways.

 

That's right.

[Johnny5]

Actually, a clock can still be useful if (using Johnny's terminology) dG/dt is a constant.

 

Dr. Swanson, is there any standard terminology for what I was referring to?

 

"Proper time" doesn't seem quite adequate, since I am referring to a property of clocks, not a property of time.

 

If I am being unclear, I know how to remedy that.

[swansont]

Dr. Swanson' date=' is there any standard terminology for what I was referring to?

 

"Proper time" doesn't seem quite adequate, since I am referring to a property of clocks, not a property of time.

 

If I am being unclear, I know how to remedy that.[/quote']

 

Rate was fine, it just isn't usually called G. You can think of that as the speed at which the clock runs (which is the rate at which the time is changing), and make some analogies to kinematics, since the same math will apply. The clock can also accelerate, i.e. the rate can change, which is called drift.

 

Rate also the frequency, which is the derivitive of the phase of an oscillator. Phase is the same as time, but since you're usually looking at some frequency output (like 5 MHz) and very small difference between clocks, the phase difference of a single cycle is often what you're looking at. It's also confusing to look at how time (of one clock) changes with respect to time (of some reference clock), so you use a different variable.

 

"Proper time" wouldn't be appropriate, since you weren't discussing phase.

 

There are also a number of noise processes you can observe in clocks, if you look at the stability (allan deviation or allan variance) of one clock compared to another. These manifest themselves as different slopes in the plot.

[Johnny5]

Rate was fine' date=' it just isn't usually called G. You can think of that as the speed at which the clock runs (which is the rate at which the time is changing), and make some analogies to kinematics, since the same math will apply. The clock can also accelerate, i.e. the rate can change, which is called drift.

[/quote']

 

Here is something on GPS and clock drift. I presume this is what you meant by clock drift:

 

Satellite clock error data

 

So a changing clock rate is called drift.

 

It would be nice if there was some universal clock which had no drift.

[Kygron]

Good ones, especially really good ones, aren't easy to make, and it's impossible for them to stay synchronized.

 

I was actually speaking WRT kriminal99's post, where the clock he needed was slightly better than the "internal" clock, i.e. a "really bad one", and those are easy

 

Its kind of hard to put into words but my point is that the subconsious definition of time is "difference between observable events" We have an internal clock so if we don't see anything going on outside of us (and I mean absolutely nothing changing) we can still gauge time by this. But the point is time would have no meaning if nothing was changing anyways.

 

Even your internal clock is composed of a changing system. For the "subconsious" to even exist requires a changing system. Your brain has developed structure that "tags" events with time differences. That process suggests a viewpoint of the environment that includes a variable we've called "time". The point of a clock is to measure this variable. We've discovered since the dawn of technology that a physical "clock" generally keeps a constant rate. We've incorporated this into all of science. Currently (as far as I know), the sciences dealing directly with time are more advanced than the philosophies dealing with time. It may be more productive to study the sciences, then build your philosophies from the most advanced forms.

 

And as you can see from the technical discussions here, time really IS relative, it's the brain and physical clocks that need to be adjusted (if they need to be that accurate)!