That is philosophy, which has it's place, but not concerning electronics or science.

There needs to be some imagination for sucess in both science and electronics.
My question on time: (My apologies for the interjection of Philosophy)
What unit of measurement do we use to calculate time?
Where did that come from?
What was the initial need for this measurement?
'Time' the way you see it may indeed exist, but the way we measure it is entirely man made. 60 seconds per minute could have been 58 seconds,
that would have a great impact on calculations.

 

That strayed far enough off of voltage and current that it now has it's own thread.

'Time' the way you see it may indeed exist, but the way we measure it is entirely man made. 60 seconds per minute could have been 58 seconds,
that would have a great impact on calculations

Assume you are timing the interval between two summer equinoxes. Make the measurement using the international second, and another using a second that is 30% different. How does this affect the duration of time between the equinoxes? You just have different numbers measuring the interval between the events.

What was the initial need for this measurement?

Every society has the interest in marking intervals of time. The granularity varies quite a bit. The perceived importance of correctly tracking the interval between significant events seems to drive the interest.

 

I'll put a copy of my rebutal in here, it had elements of both thread in the reply...

You are talking definitions. Humans are very interested in such, it helps us quantize events. In the scheme of things though, it is a human invention. Things take as long as they take, according to their natures. We need the definitions so we can describe them, but the description is not the item. Processes occur whether we observe them or not, though there is a POV that might argue this.

Time started as days, and lunar cycles. But that didn't work with seasons very well, so they added solar cycles, and have kept polishing. We now use vibrations of atoms in atomic clocks. All of this is for humans, so we can describe a unit that is relative to location and observer. Time itself existed before there was life, and will exist after we are gone (again, philosophy will debate this). I'm not a philosopher, don't have time for it.

So far we have a 50/50 split more or less. Some folks think current can exist without voltage, some don't.

 

The only way to measure time is by measuring change (motion), whether that motion be the sun or a Cesium atom. If you stop motion, you stop time.

But that brings up another big one: just because you can't measure time, does that mean that it doesn't exist? For all practical purposes I suppose it does. But hey, if everyone's all for abandoning the use of Occam's razor, we could come up with all sorts of crazy debates...

Personally, I favor practical applications. But it's fun to think about stuff like this every once in a while.

 

But that brings up another big one: just because you can't measure time, does that mean that it doesn't exist?

Isn't that like asking if no time passed after you have sat next to a broken clock?

The accepted lowest duration of time is 10\(^{-43}\) second. No change in any state can occur in less than that interval, so time has no meaning below that length.

 

What unit of measurement do we use to calculate time?
Where did that come from?
What was the initial need for this measurement?

Here are my specific answers (or opinions) to these questions.

Question 1: What unit of measurement do we use to calculate time?

Ignoring Einstein and relativity, and keeping our thinking in the simple terms that the ancients used, there is no unit of measure to calculate time. We simply count. Counting integers have no units. What do we count? We count cycles for a periodic motion of any type. We can count solar orbital cycles (years), lunar orbital cycles (months), earthly revolutions (days), cycles of a pendulum, vibrations in a crystal, atomic vibrations, heartbeats. The fact of the matter is that none of these cycles are perfectly constant and the meaning of time is really undefined until you bring in high level physics such as relativity. Newton recognized this problem and he knew that his physics of mechanics was based on a concept of time which is simply an undefined parameter in his theory.

Question 2: Where did it come from?

It came from common sense developed and evolved as a survival instinct. We observe things and conceptualize them as an ordered arrangement of events. The concept of something coming before something else, or after something else, or at the same time is intuitively obvious to us. We then note that it is useful to keep track of how events are ordered in comparison to the many periodic events that surround us. We start counting years, months, days and note the number of cycles that elapsed between interesting events. Clearly this habit or instinct has survival value. It allows planning and forethought, as well as coordinated efforts.

Question 3: What was the initial need for this measurement?

Survival. Whether on an individual level, or a group level. Measuring time helped humans survive. It is a powerful tool to use for many reasons. Knowing when animal migration occurred, or when plants would grow was (and still is) useful. Scheduling allowed societies of humans to function more efficiently. Most animals use some type of time measurement, but humans developed the ability to use it abstractly and intellectually making it much more powerful. It is not a tool of the hands, like fire or a stone axe, but it is a tool for the mind, like language. - Very useful indeed.

 

Hello,

Absolute time can be measured by counting the cycles of a cesium atom:
http://tycho.usno.navy.mil/cesium.html

Greetings,
Bertus

 

The accepted lowest duration of time is 10\(^{-43}\) second. No change in any state can occur in less than that interval, so time has no meaning below that length.

Where did you find that?

 

Sorry mik3, I do not recall the reference. Might have been Stephen Hawking's "Brief History of Time". I'm pretty confident of that value.

http://wiki.answers.com/Q/What_is_the_smallest_unit_of_measurement_in_time

 

There is a great piece on the science channel now that explains
time and time travel down to the second and time and ageing.

 

60 seconds per minute could have been 58 seconds,
that would have a great impact on calculations.

>what Bill_Marsden said

this is like saying that doing your math in base 64 would make a difference.
Or changing the length of a meter to be that of a cubit, (btw, that won't change the speed of light.)
The philosophy part of this discussion has nothing to do with the relative constants of the universe. The permeability of a vacuum isn't going to change anytime soon.

 

USNO will have the various time scales. One second is defined by international agreement. Every now and then we must add a leap-second to bring UTC within +/- 0.9 seconds of UT1.