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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