- 3112 - TIME - think about it? Using both optical fibers and invisible laser transmission of data, the researchers have measured the meaning of a second more accurately than ever before. They did it by looking at minute, the measure of size, not time, differences between time kept by the atoms.
- Measuring time gets down to measuring the length of a second. Science now is using three different elements to measure the length of a second. They have made some accuracy improvements:
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- 3.25.2021, 2:15 PM. To date, atomic clocks, which absorb and emit photons at regular frequencies to keep time are the most accurate way to measure the passage of time in seconds, but their accuracy has been stagnated for more than a decade.
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- Using both optical fibers and invisible laser transmission of data, the researchers have measured the meaning of a second more accurately than ever before. They did it by looking at minute, the measure of size, not time, differences between time kept by the atoms, a crucial step toward redefining time itself.
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- Previous attempts to measure these minute differences between how atoms keep time , referred to the ratio between them, had only ever delivered an accuracy of up to 17 digits.
That is 17 zeros after the one second decimal point.
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- Now using this new model, which includes the first-ever use of a ‘free-space link’ for this purpose using laser pulses of data going through the air instead of a cable, scientists have now measured this ratio reliably out to 18 digits.
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- The time is 3.25.2021, 2:150,000,000,000,000,001 PM
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- Cesium beam atomic clocks have long reigned supreme as the element of choice in atomic clocks, but that could soon be changing. One digit is a big deal.
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- Such frequency-ratio measurements are equivalent to determining the distance from Earth to the Moon to within a few nanometers.
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- The research team reports continued refinement of atomic clock measurements using this model has the potential to redefine the second as we know it and can help physicists test fundamental theories of the universe, including relativity and dark matter, by measuring atomic perturbations even more precisely.
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- The first atomic clock began ticking in 1949. It was powered by an ammonia molecule, but a cesium isotope quickly became the standard only a few years after.
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- Since then, scientists have relied on these incredibly precise clocks, which are largely immune to earthly headaches like earthquakes, to help keep precise time. This measurement is used to not only define time itself, but to guide satellites in orbit via GPS as well. Such a clock, called the “Master Clock,” resides at the U.S. Naval Observatory (USNO) in Washington D.C.
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- Historically, atomic clocks have worked using cesium to measure fractions of time by counting the jumps the atoms make between different energy states when exposed to certain radio-wave frequencies.
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- Since 1967, the official definition of a second has been “the duration of 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. In other words, there are just over 9 billion cesium energy jumps in one second of time.
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- While this method has worked for decades, it is still far from perfect. The oscillation frequency of cesium clocks is in the microwave region of the electromagnetic spectrum. The spectrum rainbow stretches from low energy radio waves to high energy gamma rays and describes all possible frequencies of incoming light.
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- Newer designs for atomic clocks instead focus on elements whose frequencies would in the higher frequency optical spectrum instead. These frequencies would be 100,000 times faster than the microwave range ones emitted from cesium clocks and in turn 100 times more accurate.
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- But before scientists can think about replacing the cesium in our atomic clocks, they have to prove that other elements would work even better.
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- To better measure time more accurately the researchers used three elemental clocks:
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------------------------------ An aluminum-ion atomic clock
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------------------------------ One made using ytterbium
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------------------------------ The third using strontium
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- The research team set up the aluminum-ion and ytterbium clocks at a National Institute of Standards and Technology lab in Boulder and the strontium clock roughly a mile away at the University of Colorado’s JILA lab.
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- The idea is to measure how transmitting measurement data between these distances would impact its accuracy. The data was transmitted using both a 2.2-mile long optical fiber and a 0.9-mile stretch of free-space link communication via laser pulses.
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- Over several months the team pinged this atomic data back and forth between the institutions to determine how reproducible and accurate their measurements were. The goal was not to choose the best element for a new atomic clock, but to instead perfect the ways these elements’ time-keeping accuracy was compared. With those new standards established, it would then be possible to find a replacement for cesium.
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- From their experiments, the research team was able to make the most accurate measurement to date of these ratios between the clocks and also determined that the free-space link provided the same level of uncertainty as the longer, bulkier optical fiber.
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- This new research has not yet shaken the longstanding definition of a second, but it has made serious progress toward ushering in a new era of atomic time-keeping. Continuing to refine and test these models could one day soon transform the meaning of a second, improving not only international timekeeping but boosting the accuracy of everything from self-driving cars to your FitBit as well via GPS.
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- Atomic clocks are vital in a wide array of technologies and experiments, including tests of fundamental physics. Clocks operating at optical frequencies have now demonstrated fractional stability and reproducibility at the 10^−18 level, two orders of magnitude beyond their microwave predecessors.
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- Frequency ratio measurements between optical clocks are the basis for many of the applications that take advantage of this remarkable precision. However, the highest reported accuracy for frequency ratio measurements has remained largely unchanged for more than a decade.
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- Here we operate a network of optical clocks based on 27Al+ , 87Sr and 171Yb , and measure their frequency ratios with fractional uncertainties at or below 8 * 10^−18.
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- Exploiting this precision, we derive improved constraints on the potential coupling of ultralight bosonic dark matter to standard model fields. Optical clock network utilizes not just optical fiber, but also a 1.5-kilometer free-space link.
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- This advance in frequency ratio measurements lays the groundwork for future networks of mobile, airborne and remote optical clocks that will be used to test physical laws, perform relativistic geodesy and substantially improve international timekeeping.
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---------------------------- Other Reviews about time, request number:
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- 3107 - Thinking what time is? Everything you see is younger when you see it. It takes time for the light to reach you and it is the speed of light that is constant. Time is variable it depends on where you are and how fast you are moving. It even gets more complicated.
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- 2691 - Time to Think. - Your brain has to do the same calculations to adjust positions with time, especially astronomer’s brains. Everything seen through the telescope is younger as you see that it is at the time you see it. It takes time for light to reach us, especially at astronomical distances. Light from the Sun is 8 minutes old, and that is the closest star.
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- The next closest star is 4 ½ years younger as we see it. It takes 4 ½ years for the light to reach us.
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- 2205 - Optical Lattice Clock.
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- 2422 - The Beginning of Time - If you could run the clocks backward 13,700,000,000 years you would reach the beginning of time. Thought to be the creation of time and space. The end of time would be the end of endings. The boundaries of time seem to be the boundaries of our reasoning as well
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- 2087 - Is Time slowing Down?
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- 2420 - Time to Think, again
- 854 - Time, GPS, and Entropy
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- 2381 - Pressed for Time
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- 2800 - A 24 hour Day - Time - How do you go from GPS time to Universal Time, just add 19 seconds. Why?
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- 2523 - Fast Speed and Short Time - The smallest fraction of time is 10^-43 seconds. That is how long it takes light to travel the smallest possible distance, 10^-35 meters. If a distance got any smaller it would become a mini-blackhole ( See Reviews 2526 and 2738)
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- 2386 - Time is what God created - to prevent everything from happening all at once.
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- 2123 - Why 60 minutes.
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- 356 - Time is Getting Short - Zeptosecond pulses ( 10^-21) are used to study nuclear events in side an atom. We are not there yet with our technology. Attoseconds ( 10^-18) is used to study electrons orbiting the nucleus in atoms. Femtoseconds (10^-15) measures chemical reactions and the interactions of molecules.
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- 2166 - Jim’s Universal Calendar. History from 10^-43 seconds to today summarized in 19 pages.
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- 2379 - Deriving Time Dilation from the Pythagorean Theorem. Sorry, that is all the time I have.
- March 23, 2021 TIME - think about it? 3101
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