Posted on 01/19/2018 10:32:02 AM PST by MtnClimber
Just what is a second, exactly? The question has been open to interpretation ever since the first long-case grandfather clocks began marking off seconds in the mid-17th century and introduced the concept to the world at large.
The answer, simply, is that a second is 1/60th of a minute, or 1/3600th of an hour. But that’s just pushing the question down the road a bit. After all, what’s an hour? That answer is related to the best means of time-keeping ancient civilizations had — the movement of the Earth through the heavens. The amount of time it takes for the Earth to turn once about its axis, or for it to rotate once about the sun, is fairly stable, and for much of human history, it sufficed as a way of marking the passage of time. Days, hours, minutes — they’re all just derivatives of planetary motion.
Today, however, when computers perform operations at the rate of 4 billion cycles per second, we need a better measure. The rotation of Earth, and its orbit, change slightly over time. Earth’s rotation, for example, is slowing slightly. So measuring a second based on rotation would mean that a second would get slowly longer over time. Ultimately, we couldn’t compare the second of today to the second of yesterday.
So, to pin down a truly timeless measure of a second, scientists in the 1950s devised a better clock, one based not on astronomical processes but on the movement of fundamental bits of matter — atoms — whose subtle vibrations are, for all intents and purposes, locked in for eternity. Today, one second is defined as “9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom”.
That’s a mouthful.
(Excerpt) Read more at blogs.discovermagazine.com ...
I talked with a guy (a physics research professor) a few years back on the subject of there being a very fine deviation in radioactive decay constants (which would have significant ramifications in the theoretical sense at the least). The thinking was that it was linked to the sun and possible variances in something like solar neutrino output.
The Hebrew calendar uses lunar cycles for months, but adds ‘leap months’ to keep it in sync with the solar year.
A “day” is the earth spinning on it’s axis and begins when the sun is opposite your location on the planet which is midnight. Noon is when the sun is directly above your meridian of longitude as the earth continues its spin the time is after noon or PM “post(your)meridian.
A “day” begins and ends at night.
It takes ~365.25 days to orbit the sun currently so that is a year. We add one full day every 4th year (leap year is in 2020) to the month of February to correct for that 0.25 day otherwise the seasons would drift out of the winter, spring, summer and fall alignment with certain months.
No! and not because we compare it to earths rotation. At different temperatures and pressures the atomic vibrations change. At absolute 0 there are no vibrations and an atomic clock is useless.
All measurements should mimic the decimal system. One hundred seconds in a minute, 100 minutes in an hour, 10 hours in a day. Go to the metric system also. Our current measurement system is nuts!!!
That does not answer the question, “WHY are there 24 hours in a day?”..................
Ask Einstein about the effect of gravity on time. There is no absolute measure of time. Or anything.
Julius Cesar dumped the lunar calendar for a solar one but Pope Gregory the XIII changed it to reflect the birth of Christ (sort of). We are using the Gregorian calendar as of October 1552. Other cultures use other calendars.
I think the math goes back to some point in history. I never read up on this.
There are 360 degrees in a circle. I think that’s because of the year being close to 360
24 hours in a day
60 minutes
60 seconds
All of these are factors of 12
Here’s a hint:
Ancient Egypt.........................
Little known fact:
Originally, February was decreed as Diet Month. An opportunity to prepare for swimsuit season and shed some winter pounds. A vote was taken by the Time Lords and it was unanimous to not add anymore days to February than necessary for fear of upsetting the women of the realm.
Thus February remains the only month with a mere 28 days.
If the clock moved at near-light speed, the cycling between the two energy states and thus measurement of seconds would be slower, as judged by a stationary observer
Sounds like something they would have, and probably did, tried to change during the French Revolution.
It is also of interest why Sept, Oct, Nov, and December are named the seventh, eight, ninth, and tenth months while actually ranking 9 10, 11, and 12.
Shouldn’t it be named after Kronos?
A better question: Why did 2008-to-2016 seem like an eternity?
“10 hours in a day”
On which planet?
And then, how many hours of sleep does the human body require each “day”?
How about 13 28-day months with one or two days of New Year celebrations?
"He wants his kilogram of flesh."
No. It just doesn't work for me.
Because after 24 hours, it's tomorrow...
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