[rollei_list] Re: ...was Avedon OT Time


On Dec 20, 2010, at 01:33 PM, CarlosMFreaza <cmfreaza@xxxxxxxxx> wrote:

Time definition for practical purposes allowed the Newton mechanics
and it allowed the Space travels, Einstein concept about time could
have some practical use some day but most of other ideas about time
are pure speculation and don't have practical applications, except for
literature and/or to do literature, from this point of view, _time is
a measurable sequence of light crossing the space that started some
day and will end some day being the universe the light that travels_.

Carlos
 
OK Folks:
In Citing the Wikipedia entry on time units, I was responding to this sentence:
"it's clear that even though there seems to be no scientific definition of
time" in a previous post, and offering as a counter example an operational definition of a unit of time.  I then went on to try and indicate that our understanding of time is quite similar to our understanding of space, and that all these concepts get quite blurred when we try to look at them too closely. 
I also understand the ambiguity in the concept of time itself, which has been a preoccupation of philosophy. There is a nice article in the Stanford Encyclopedia of Philosophy Here: http://plato.stanford.edu/entries/time/.  (I like the Stanford, it was recommended to me by two philosophers).
Much of philosophy appears to be to be a matter of operational linguistics, and much of how we see the world may well be public manifestations of the deep structure of our Brains. Kenneths contribution is fascinating here.
Einstein's special and general relativity, far from being purely abstract are used by millions of people every day, including, I would suspect members of this list.  Accurate Sat Nav. results depend on general relativistic corrections.
Finally Wikipedia. "That corrupt piece of Junk"...  Wikipedia is a Web 2 tool.  Using Web 2 tools requires a very different mindset from traditional sources. Just as Twitter is a great source of news, used by many newspapers, but is not a newspaper.
I could, and may say more later but I've got to do a run to the sea-scouts Christmas party.
Back later and looking forward to continuing this conversation.
All the best
Larry Cuffe
(Eric Sorry for the "Dr" in my earlier post, I try to keep work and pleasure emails separate, but my fingers slip at times)





2010/12/20 Eric Goldstein <egoldste@xxxxxxxxx>:
> Carlos-
>
> Yes, that is correct, but it was not the answer to the question raised
> relative to what time is (or is not).
>
> The fact that the strontium clock may or may not become a world
> standard has nothing to do with anything, including the issue under
> discussion. You are conflating bits of information into erroneous
> assumptions and conclusions.
>
> Other than that, your post is perfect ;-) (teasing)
>
> Seriously, I'm meanly pointing out one of the intrinsic limitations of
> definitions of time. I'll say again that whether time does or does not
> "exist" is entirely irrelevant in a universe as it is known today...
>
>
> Eric Goldstein
>
> --
>
> On Mon, Dec 20, 2010 at 1:04 PM, CarlosMFreaza <cmfreaza@xxxxxxxxx> wrote:
>> Eric:
>>        Wikipedia is right about the Cesium 133 clocks is establishing
>> the time standard yet since the UTC is the time standard for the world
>> and it is still  based on Cesium 133 clocks and then it is valid the
>> second definition from 1967 based on Cesium 133. Strontium and other
>> elements clocks are more exact than the clocks based on Cesium 133,
>> however this fact has sterted to be demonstrated a few years ago and
>> it will still take a long time before these clock become and
>> international standard, they are useful for some specific purposes but
>> regarding the universal and general time measurement Cesiem 133 is
>> still the rule.
>> BTW, Wikipedia is a great tool IMO.-
>>
>> Carlos
>>
>>
>>
>>
>> 2010/12/20 Eric Goldstein <egoldste@xxxxxxxxx>:
>>> Hi Dr Larry -
>>>
>>> Google "strontium atomic clock" and you will have your answer. The
>>> fact that cesium is a time standard for ordinary purposes does not in
>>> any way mean it is the definitive standard. As for the beauty of
>>> Wikipedia, don't get me started on that corrupt piece of junk which
>>> passes as some sort of reasonable reference..
>>>
>>>
>>> Eric Goldstein
>>>
>>> --
>>>
>>> On Mon, Dec 20, 2010 at 12:22 PM, Laurence Cuffe <cuffe@xxxxxxx> wrote:
>>>>
>>>>
>>>> On Dec 20, 2010, at 11:10 AM, Eric Goldstein <egoldste@xxxxxxxxx> wrote:
>>>>
>>>> Good old Wikipedia. Cesium is no longer the scientific standard of the
>>>> second... it is not precise enough.
>>>>
>>>>
>>>> Eric Goldstein
>>>>
>>>>
>>>> That's the beauty of Wikipedia, if you know that something is wrong, you can
>>>> go in and fix it yourself!
>>>> I'm not sure that the Cesium has been supeceeded,
>>>> This bunch (The US national institute of standards) also seem to feel its
>>>> valid:
>>>> http://physics.nist.gov/cuu/Units/second.html
>>>> There may be experimental work which has developed a more accurate time
>>>> standard, however adapting that into international law, can take time.
>>>> Quite seriously, I'd love a reference.
>>>> All the best
>>>> Dr Laurence Cuffe
>>>>
>>>> --
>>>>
>>>> On Mon, Dec 20, 2010 at 10:49 AM, Laurence Cuffe <cuffe@xxxxxxx> wrote:
>>>>>
>>>>>
>>>>> On Dec 19, 2010, at 10:07 PM, Don Williams <dwilli10@xxxxxxx> wrote:
>>>>>
>>>>>
>>>>> Today, the fundamental unit of time suggested by the International System
>>>>> of
>>>>> Units is the second, since 1967 defined as the second of International
>>>>> Atomic Time, based on the radiation emitted by a Caesium-133 atom in the
>>>>> ground state. Its definition is still so calibrated that 86,400 seconds
>>>>> correspond to a solar day. 31,557,600 (86,400 × 365.25) seconds are a
>>>>> Julian
>>>>> year, exceeding the true length of a solar year by about 21 ppm.
>>>>>
>>>>> At 06:58 AM 12/17/2010, Carlos wrote:
>>>>>
>>>>> Don:
>>>>>         I could copy definitions, every viewpoints, etcetera from
>>>>> different sources, but I think it would be more easy to read this
>>>>> Wikipedia article:
>>>>> http://en.wikipedia.org/wiki/Time
>>>>>
>>>>> Carlos
>>>>>
>>>>> Yes, I have read that entry and in the first paragraph it says: "Time has
>>>>> been a major subject of religion, philosophy, and science, but defining it
>>>>> in a non-controversial manner applicable to all fields of study has
>>>>> consistently eluded the greatest scholars."
>>>>> ________________________________
>>>>> I just noticed the above incomplete response on the subject.  I had been
>>>>> holding this message in order to find a statement by Einstein, that he
>>>>> couldn't define time, but it's buried somewhere in a 400 page bio I have
>>>>> been reading and I can't easily find that sentence  Just trust me that he
>>>>> did say that.
>>>>>
>>>>> Einstein even used time as a fourth dimension, and also attempted to prove
>>>>> that the universe is curved back on itself.  Current evidence now points
>>>>> to
>>>>> a flat universe.  He even won a Nobel Prize in Physics, but not for his
>>>>> work
>>>>> on relativity.
>>>>>
>>>>> Interesting situation, Hawking wrote a Brief History of Time, but even
>>>>> there
>>>>> he didn't define the term.
>>>>>
>>>>> It's clear that even though there seems to be no scientific definition of
>>>>> time, we all use it, mutually understand what the word means, and are not
>>>>> hampered in our daily lives by the lack of such definition.
>>>>>
>>>>> DAW
>>>>>
>>>>>
>>>>> Scientific definition of a unit of time. Wikipedia, Units of Time.
>>>>> Today, the fundamental unit of time suggested by the International System
>>>>> of
>>>>> Units is the second, since 1967 defined as the second of International
>>>>> Atomic Time, based on the radiation emitted by a Caesium-133 atom in the
>>>>> ground state. Its definition is still so calibrated that 86,400 seconds
>>>>> correspond to a solar day. 31,557,600 (86,400 × 365.25) seconds are a
>>>>> Julian
>>>>> year, exceeding the true length of a solar year by about 21 ppm.
>>>>> We can, as scientists, define time  with about the same level of certainty
>>>>> with which we can define distance, and mass. All of these entities when we
>>>>> look closely become quite slippy as concepts. For instance, the length of
>>>>> a
>>>>> meter stick, which seems a very concrete thing, turns out to depend in a
>>>>> very real way on which way and how fast you are traveling when you measure
>>>>> it.
>>>>> Similarly duration depends on the relative velocities of the observers
>>>>> discussing it, and also depends on how deep into a gravity well you have
>>>>> descended, This effect is real, a height difference of 12 meters can put
>>>>> two
>>>>> Iron atoms out of sinc with each other so that they can no longer have the
>>>>> same energy levels. (http://en.wikipedia.org/wiki/Pound-Rebka_experiment)
>>>>> Even before and after is up for grabs. So long as two events are too far
>>>>> apart for a light beam to get from one event to the other before the other
>>>>> event happens in some rest frame, than its possible to find another rest
>>>>> frame, where the second event will happen before the first.
>>>>> This is all fascinating stuff, and although I touched on it in college, I
>>>>> find MIT open courseware, and even ITunes U (both free!) a great source of
>>>>> world class lectures on this material.
>>>>> All the best
>>>>> Larry Cuffe
>>>>>
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