- 2880 - ZEPTOSECONDS - how time flies? Since the spatial orientation of the hydrogen molecule was known the interference of the two electron waves was used to precisely calculate when the photon reached the first and when it reached the second hydrogen atom. That time? Two hundred and forty-seven zeptoseconds. The measurement is essentially capturing the speed of light within the molecule.
--------------------------- 2880 - ZEPTOSECONDS - how time flies?
- The smallest conceivable length of time might be no larger than a millionth of a billionth of a billionth of a billionth of a second. That's according to a new theory describing the implications of the universe having a fundamental clock-like property whose ticks would interact with our best atomic timepieces.
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- Such an idea could help scientists get closer to doing experiments that would illuminate a theory of everything, an overarching framework that would reconcile quantum mechanics, which looks at the smallest objects in existence, and Albert Einstein's relativity, which describes the most massive ones.
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- Most of us have some sense of time's passage. But what exactly is time?
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- We don't know. We know that things change, and we describe that change in terms of time.
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- Physics presents two conflicting views of time. One, which stems from quantum mechanics, speaks of time as a parameter that never stops flowing at a steady pace. The other, derived from relativity, tells scientists that time can contract and expand for two observers moving at different speeds, who will disagree about the span between events.
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- In most cases, this discrepancy isn't terribly important. The separate realms described by quantum mechanics and relativity hardly overlap. But certain objects, like black holes, which condense enormous mass into an inconceivably tiny space, can't be fully described without a theory of everything known as “quantum gravity“.
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- In some versions of quantum gravity, time itself would be quantized, meaning it would be made from discrete units, which would be the fundamental period of time. It would be as if the universe contained an underlying field that sets the minimum tick rate for everything inside of it, sort of like the famous Higgs field that gives rise to the Higgs boson particle which lends other particles mass. But for this universal clock, instead of providing mass, it provides time.
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- By modeling a universal clock would have implications for human-built atomic clocks, which use the pendulum-like oscillation of certain atoms to provide our best measurements of time. According to this model, atomic clocks' ticks would sometimes be out of sync with the universal clock's ticks.
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- This would limit the precision of an individual atomic clock's time measurements, meaning two different atomic clocks might eventually disagree about how long a span of time has passed.
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- Given that our best atomic clocks agree with one another and can measure ticks as small as 10^-19 seconds, or a tenth of a billionth of a billionth of a second, the fundamental unit of time can be no larger than 10^- 33 seconds.
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- Research of this type tends to be extremely abstract, he added, so it was nice to see a concrete result with observational consequences for quantum gravity, meaning the theory could one day be tested.
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- While verifying that such a fundamental unit of time exists is beyond our current technological capabilities, it is more accessible than previous proposals, such as the Planck time.
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- Derived from fundamental constants, the Planck time would set the tiniest measurable ticks at 10^- 44 seconds, or a ten-thousandth of a billionth of a billionth of a billionth of a billionth of a billionth of a second.
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- Because the universe itself began as a massive object in a tiny space that then rapidly expanded, cosmological observations, such as careful measurements of the cosmic microwave background, a relic from the Big Bang, might help constrain the fundamental period of time to an even smaller level.
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- When we try to observe a quantum event at a point in time, we encounter the uncertainty principal in that at a precise point in time, the exact state is uncertain and vice-versa.
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The problem with discrete time is that it doesn't work relativistic ally, we can't have "preferred" reference frames, and it is generally accepted that relativity says space and time is continuous on all scales. Rather, the scale problem comes when you use the reconciliation of general relativity and quantum field theory that we have a linear zed gravity quantum field theory
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- In general quantum superposition, which is what Schrodinger's cat illustrates, as well as quantum entanglement, depends on non-locality and no hidden variables of quantum correlations.
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- Relativity enforces light cone locality in order to have causality but quantum physics opens up as much non-locality of correlations it can have. It is an exact balance and is made explicit in quantum field theory which obeys relativity.
Scientists have measured the shortest unit of time ever: the time it takes a light particle to cross a hydrogen molecule. That time, for the record, is 247 zeptoseconds.
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- A zeptosecond is a trillionth of a billionth of a second, or a decimal point followed by 20 zeroes and a 1.
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- In 2016, researchers reporting in the journal Nature Physics used lasers to measure time in increments down to 850 zeptoseconds.
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- This accuracy is a huge leap from the 1999 Nobel Prize-winning work that first measured time in femtoseconds, which are millionths of a billionths of seconds.
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- It takes femtoseconds for chemical bonds to break and form, but it takes zeptoseconds for light to travel across a single hydrogen molecule (H2).
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- To measure this very short trip X-rays were shot from the PETRA III at Deutsches Elektronen-Synchrotron (DESY), a particle accelerator in Hamburg.
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- The researchers set the energy of the X-rays so that a single photon, or particle of light, knocked the two electrons out of the hydrogen molecule. A hydrogen molecule consists of two protons and two electrons.
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- The photon bounced one electron out of the molecule, and then the other, a bit like a pebble skipping over the top of a pond.
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- These interactions created a wave pattern called an interference pattern that was measured with a tool called a Cold Target Recoil Ion Momentum Spectroscopy (COLTRIMS) reaction microscope. This tool is essentially a very sensitive particle detector that can record extremely fast atomic and molecular reactions.
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- The COLTRIMS microscope recorded both the interference pattern and the position of the hydrogen molecule throughout the interaction.
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- Since the spatial orientation of the hydrogen molecule was known the interference of the two electron waves was used to precisely calculate when the photon reached the first and when it reached the second hydrogen atom.
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- That time? Two hundred and forty-seven zeptoseconds. The measurement is essentially capturing the speed of light within the molecule.
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- The electron shell in a molecule does not react to light everywhere at the same time. The time delay occurs because information within the molecule only spreads at the speed of light.
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- How did we get from heartbeats to zeptosecond, one second sat a time.
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- The human heart beats once per second, lightning strikes in 1/100th of a second, 10^-2 seconds. In everyday photography a camera can stop time at about 1/1000th of a second, 10^-3 seconds. Computers work at clock speed of 10^-9 seconds, a billionth of a second.
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- Circuits have electrical switches that can operate at 10^-12 seconds, a trillionth of a second. Scientists today are working with laser pulses that can stop time at 650 *10^-18 seconds, 650 attoseconds.
- About 30 years ago lasers could create a pulse of 6 femtoseconds, 6*10^-15 seconds. If one femtosecond is to 90 seconds, then 90 seconds is to the age of the Universe, 13,700,000,000 years. Chemical bonds break and reform in molecules in about 100 to 200 femtoseconds, 200*10^-18 seconds.
- Two years ago lasers could create a pulse that was 650 attoseconds long, 650 *10^-18 seconds. The is fast enough to stop the motion of an electron in an atom. In nuclear physics the natural timescales inside an atom are in the order of zeptoseconds, 10^-21 seconds.
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- We have just to invented the laser that can stop the motions inside the nucleus of an atom.
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------------------------- deci ------------ 10^-1
------------------------- centi ------------ 10^-2
------------------------- milli ------------ 10^-3
------------------------- micro ----------- 10^-6
------------------------- nano ------------ 10^-9
------------------------- pico ------------ 10^-12
------------------------- femto ---------- 10^-15
------------------------- atto ------------ 10^-18
------------------------- zepto ---------- 10^-21
------------------------- yocto ---------- 10^-24
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- Attoseconds and zeptoseconds seem incomprehensible, how can one even imagine these timescales?
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- Ok, let’s say you have a really, really fast motorcycle that would travel from Los Angeles to New York in one nanosecond, 10^-9 seconds to travel 2,787 miles. In one picosecond, 10^-12 seconds, the fast motorcycle would have only traveled 2.8 miles, barely getting to East L.A. In one femtosecond, 10^-15 seconds, it would have traveled about 1/5th of an inch.
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- If you held on and your motorcycle really went that fast, in one second it would have passed New York , went into orbit and circled the Earth 112,000,000 times, in one second. “How time flies.”
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- If you were in a race with your motorcycle and you won by a single attosecond (10^-18 seconds) you would have won the race by less than the width of an atom, in fact, in less that the width of a proton. If you were second place your time would have been the same as the first place motorcycle plus 0.000,000,000,000,000,001 seconds. That was close.
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- The smallest fraction of time is thought to be 10^-43 seconds. It is called a Planck second. That happens to be the time it takes light the fastest thing possible to travel the smallest distance of space 10^-35 meters, called the Planck Length.
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- The reason this is the smallest unit of length is that if it got any smaller it would become a Black Hole. See Review 2526 for the details. The last thing we want to be is near a Black Hole. Or, maybe we are inside one now and the edge of the Black Hole is the edge of the Observable Universe. Nothing even light can escape from the Observable Universe, or, if it can we can’t see it.
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- So, maybe from the outside looking in the Universe is a Black Hole. The Observable Universe is 1.3*10^26 meters. When you go backwards in time and reduce that to 10^-35 meters you enter another Black Hole.
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- What do you suppose happens to space and time inside a Black Hole? We have more to learn.
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------------------------------- For more info see Reviews:
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- 1242 - How does spacetime change at the micro level?
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- 2271 - Hw can space and time be related? Also lists 13 more reviews about spacetime.
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- 2213 - Spacetime from atoms to blackholes.
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- 2180 - Velocity is space divide by time.
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- 1790 - Space bends and time slows.
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- 2522 - Space - curved or flat? Also, lists 14 more reviews about space.
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- 2523 - Fast speed and short time
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- October 27, 2020 2880
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--------------------- --- Wednesday, October 28, 2020 ---------------------------
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