>Don Mikulecky replies:
>Time is labeled by a clock. What we can do is mark simultaneous instants.
We
>can also discern non-simultaneous events as prior or subsequent. that's
the
>best we can do. This is a labeling, not measurement.
There is a little more to time than this.
To object-ify (semantically align) it: Say, for simplicity, you have two
lengths, one is expanding (length A) the other is static (length B). If I
say no more, most people would accept this without thought. The default
assumption is that one length is static since it doesn't change with respect
to time and the other isn't because its length is changing with respect to
time. We assume that "with respect to time" is a necessary part of the
definition of static or dynamic. When in fact, we could just as well say
that length A is static and length B is contracting. This obviously throws
a wrench in the "marking" time idea -- at least with respect to absolute
time since what we think of as a clock ususally has something of a dynamic
character. BUT this dynamic is only possible with respect to some object
we define (by default assumption) as a static reference. The simplest
clock must have at least a static and a dynamic component. Since you can't
establish dynamic without comparision to a defined static, I think of this
as a qualitative measure.
This of course makes distinguishing between static and dynamic seem
subjective. Instead it makes distinguishing between static and dynamic a
general principal: you can, in principle, define any two arbitrary points in
the universe as a static reference length (no prefered rulers). Then by
comparing this length to others you can categorize the other static lengths
and the other variety of dynamic lengths.
As a simple example of this generality, take two frames. A is the expanding
frame and B is the static one. If these two are interchangeable with
respect to static and dynamic then they are equivalent. And so we can
relate a unit length in frame A to an equivalent unit length in frame B via
a simple transformation. Let d be the unit distance in the static frame and
v be the unit length in the expanding frame. Then to transform the dynamic
unit length to the static unit length we apply a transform t and we have:
d = vt
(you can elaborate quite a bit on t, but I'll save my wind until I'm sure I
know what I'm talking about.)
or t = d/v. This is in fact a very simple, object-ive and general measure
of time. You have d as the object being measured by a reference object v
and t expressed the number of v's in d.
Regards
Jack Martinelli
>
>Jack Martinelli wrote:
>
>> >Don mikulecky replies:
>> >
>> >John J. Kineman wrote:
>> >
>> >> Kineman replies to Mikulecky regarding Rosen's concept of time:
>> >>
>> >> Note: this picks up from the thread: Re: Rosen's def => A car is not
a
>> >> machine !
>> >> and also: Re: Can we agree on what a machine is?
>> >>
>> >> >> "We may point out explicitly that there is no absolute or objective
>> >> >> character to [time]."
>>
>> Whoa! This is false. Although there is no absolute character to time,
it
>> is farily easy to construct an
>> objective procedure for measuring it. Our sense of time is subjective.
>> If this is what you want to model, then good luck.
>>
>> [...]
>>
>> >ah...there's the rub....as Rosen points out...the best we can do is
"label"
>> > time,
>> >we do not measure it.
>>
>> If we don't measure time, what is it that a clock does? And how would
you
>> compare this kind of encoding to our procedure for measuring length? Is
>> there anything common to both?
>>
>> Regards
>>
>> Jack Martinelli
>>
>> http://www.martinelli.org
>