A phenomenon of quantum mechanics known as superposition can impact timekeeping in high-precision clocks, according to a theoretical study from Dartmouth College, Saint Anselm College and Santa Clara University.

Research describing the effect shows that superposition — the ability of an atom to exist in more than one state at the same time — leads to a correction in atomic clocks known as “quantum time dilation.”

The research, published today (October 23, 2020) in the journal *Nature Communications*, takes into account quantum effects beyond Albert Einstein’s theory of relativity to make a new prediction about the nature of time.

“Whenever we have developed better clocks, we’ve learned something new about the world,” said Alexander Smith, an assistant professor of physics at Saint Anselm College and adjunct assistant professor at Dartmouth College, who led the research as a junior fellow in Dartmouth’s Society of Fellows. “Quantum time dilation is a consequence of both quantum mechanics and Einstein’s relativity, and thus offers a new possibility to test fundamental physics at their intersection.”

In the early 1900s, Albert Einstein presented a revolutionary picture of space and time by showing that the time experienced by a clock depends on how fast it is moving — as the speed of a clock increases, the rate at which it ticks decreases. This was a radical departure from Sir Isaac Newton’s absolute notion of time.

Quantum mechanics, the theory of motion governing the atomic realm, allows for a clock to move as if it were simultaneously traveling at two different speeds: a quantum “superposition” of speeds. The research paper takes this possibility into account and provides a probabilistic theory of timekeeping, which led to the prediction of quantum time dilation.

To develop the new theory, the team combined modern techniques from quantum information science with a theory developed in the 1980s that explains how time might emerge out of a quantum theory of gravity.

“Physicists have sought to accommodate the dynamical nature of time in quantum theory for decades,” said Mehdi Ahmadi, a lecturer at Santa Clara University who co-authored the study. “In our work, we predict corrections to relativistic time dilation which stem from the fact that the clocks used to measure this effect are quantum mechanical in nature.”

In the same way that carbon dating relies on decaying atoms to determine the age of organic objects, the lifetime of an excited atom acts as a clock. If such an atom moves in a superposition of different speeds, then its lifetime will either increase or decrease depending on the nature of the superposition relative to an atom moving at a definite speed.

The correction to the atom’s lifetime is so small that it would be impossible to measure in terms that make sense at the human scale. But the ability to account for this effect could enable a test of quantum time dilation using the most advanced atomic clocks.

Just as the utility of quantum mechanics for medical imaging, computing, and microscopy, might have been difficult to predict when that theory was being developed in the early 1900s, it is too early to imagine the full practical implications of quantum time dilation.

Reference: “Quantum clocks observe classical and quantum time dilation” by Alexander R. H. Smith and Mehdi Ahmadi, 23 October 2020, *Nature Communications*.

DOI: 10.1038/s41467-020-18264-4

I’ve always wondered how scientists actually measure the movement they are talking about, isn’t that relative also. Think about it the Earth is spinning on its axis, also around the sun all the sun also is moving in the galaxy and our galaxy is expanding, so where and how are you measuring movement?

Yes, it’s all relative. The cosmic microwave background has been used as a proxy for a universal reference frame, as have distant quasars, but strictly speaking, there is no such thing.

The relativistic point of reference is relative to the observers. There is no one absolute reference point.

If we use a point on the equator it will give a different result that a point like the Greenwich Naval Observatory – due to differences in angular momentum due to a difference in latitude on the rotating globe.

You really don’t need to. It’s relative motion. Generally, you have one object at a relativistic speed and one that’s not.

Thanks

Terry Pratchett wrote a book about making the most precise clock. It turned out to be the Auditors trying to wipe out humans again. Hmmm…they found Earth.

You question is excellent! The answer may surprise you. All motions of any kind are measured with respect to something else, i.e. they are relative motions. There is no such thing as “absolute motions: except in two cases. The first is Newtonian which just says when you apply a force to a body it will accelerate and therefore move faster than it was and that is a type of absolute motion reference frame but only for accelerations. Motions including this one must still be measured relative to something else. Now here’s the kicker, Relativity does give us an absolute motion measurement because light from any object in motion must always travel at exactly C no matter from what reference frame it is measured. This gets into time dilation of one reference frame to another and the result is every reference frame see C exactly as the same absolute speed measure, but this is very much complicated by any time dilations operant at each reference frame. So in fact although C is an absolute speed measurement indecent of any reference frame, it can not be used to get around measuring any bodies traveling less than C must be measured relative to each other. But its not so bad, almost everything is measured astrophysically as the speed relative to the Earth so at least the same reference frame is used so speeds can be compared. An interesting one to consider is a satellite orbiting the Earth; at what speed is it moving? By Newton’s inverse square law of gravity the orbital speed is fixed by the mass of the object orbited but it is always the relative speed with respect to the object orbited. Now imagine lots of orbits within the solar system. Like you said everything moves so everything above applies but the relative speed of say a orbiting satellite is as stated above but it can also be calculated relative to any other body for example the sun which is traveling also within the galaxy. Not a simple situation! But that’s the way it works. The study of all this is called Celestial Mechanics and that is an extremely complicated and endeavor but essential for space travel among the planets. Hope this helps and give you some grounds for future thoughts.

Quantum time dilation is only speculation here and must be measured and confirmed which as it says is almost impossible. Frankly relative motion between two quantum probability wave functions resulting in time dilation is kind of a nutty idea. But if it proves out it would be very interesting. (Lots of people have been trying to merge the Quantum with Relativity. That may not be necessary. Case in point, very precise measurements of the old Newtonian gravity law between quantum atomic particles have been carried out with extreme precision and no deviation from Newton’s very old prediction has been found as a result of measurement between these quantum particles. The two laws could coexist as a mesh and both operate as they do with one not affecting the other at all as in this example. Nature obeys its laws without care of man’s desires.)

A quantum superposition of infinite spacetime fields in General Relativity! What a terrifying, awe-inspiring thought.

To Ralph Drayman, I have something that you may be interested in and I have discovered by investigating in my neighborhood and small city now for 4 years. Please contact me at [email protected]. C. W.

They really should have published this two days sooner, on Back to the Future day.

I am enjoying this article,as a “layman” it is difficult to fully understand. I am learning. That’s the wonderful part.

Another piece of harry-potter-science; http://viXra.org/abs/1509.0272?ref=10974260

“…the time experienced by a clock depends on how fast it is moving” is a bit misleading. It implies that the clock really does slow down. It doesn’t – not from its own point of view.

We normally define reality as how things are from their own POV. If we want to use a different POV we should make this clear:

“….the ticking-rate of a clock appears to slow down depending on how fast we are moving relative to it.”

There seems to be a fairly recent effort to apply relativity outside of relativistic quantum field theory – which harmonize relativity and quantum physics on flat space, i.e. enforces special relativity – and after seeing how relativity applied to entanglement can enforce the Born postulates of observation (“waveform collapse” in some descriptions of Copenhagen’s “shut up and calculate”) I find the paper promising [ https://www.nature.com/articles/s41598-020-72817-7.pdf ].

The proposed effects are small – at least in flat space – nothing like the basic relativistic “time dilation” (or “length cointraction”). We’ll see how it bears up in tests.

FWIW, I did not however like the early efforts this paper mentioned, since those tried to add postulates to “shut up and calculate” barebone quantum physics, which we know works.

Nice comments so far, that is refreshing!

@ Roto: “Frankly relative motion between two quantum probability wave functions resulting in time dilation is kind of a nutty idea. But if it proves out it would be very interesting. (Lots of people have been trying to merge the Quantum with Relativity. That may not be necessary.”

Interesting comments! I note that interplanetary space travel is newtonian, and I expect that any crafts we send out will approximate that. But that sentiment is well spoken!

Now to the topic here (and I now note in posting I became lengthy):

The attribution of reference frames to particles is the point that I have trouble with in their original reference to the field – reference frames apply to “observers”. and, say, entanglement show that particles can be part of non-local correlated systems. But wavepackes as proxy for particles are states that objectively should be able to “observe”, so it doesn’t seem too low a possibility to me.

I would say that quantum physics and relativity was combined with the discovery of relativistic quantum field theory, which e.g. remove the idea of classical “wave-particle” duality and makes the creation and annihilation of the resonant ripples that are particles part of the field. Quantum field theory works well on flat space, and path integral formulations separate out the Lorentz transformation metric as a multiplicative factor and gravity as an additive factor if you try to apply it on the tensor field of general relativity [search “Core Theory T-shirts” @ Preposterous Universe to get a quick look at Nobel Prize winner Weinberg’s Core theory of everything as quantum particle fields; and “Quantum gravity as a low energy effective field theory @ Scholarpedia].

Gravity is the weakest force and so the last that fails at the universal energy density limit of Planck energy density, none of which we observe in cosmology. E.g. the highest internal energies of the universe happens under the era of the inflation scalar field and its energy density is several orders of magnitude below Planck energy density [Planck collaboration cosmological parameter paper, 2018]. Instead we observe that space is on average flat over sufficiently large volumes [ibid; eBoss galaxy survey collaboration 20 year summary cosmological paper, 2020]. Give or take the curvature of black holes – I estimate the edge of the M87* black hole shadow lies at a gravity strength of ~10^9 times Earth surface gravity [but someone should check me]. But if scalar fields are constant density, vector fields field lines are mathematical tools (where particle pathways really are volume filling according to the mentioned Feynman path integral formulation, with the field lines only approximating the most dense volumes of that distribution), why would tensor fields geodesics be any different? Hence I have a vague notion that we have a physics where we already have a quantum gravity that works and that the mentioned “merger” is unnecessary – but because it has already happened.

@Laszlo G Meszaros: That pseudoscience site is indeed reminiscent of recent “magic movies”. 🙂

ERRATA: Wilczek’s Core theory.

ADDENDUM: “why would tensor fields geodesics be any different?” I.e. why wouldn’t geodesics also be convenience tools, having no real physical template, akin to how scalar field need mone and vector field have field lines. With a cosmological observed background of flat space, there is no inherent problem of “solving topology” by way of relying on classical general relativity, we can perhaps rely entirely ion quantum gravity.

[That is part of why I like the new time dilation effect and it being so small – though I shouldn’t “like” it before it is tested. A problem with “everything is quantum field” synthesis is it moves the prospect of understanding where time and space “came from” more distant. Though we have Noether’s theorems of momentum and energy conservation – space being uniform enforces conserved momentum, time being uniform enforces conserved energy – which is essential for having particle fields. I’m falling back on another Noble Prize winner Weinberg’s “anthropic multiverse”. Which by the way got a hail by being shortlisted in the eBOSS cosmology paper for explaining the low value of “dark” vacuum energy density we observe.]

Does time have a superposition?

Amd if so, if that given point exists in a super position, could that act as an anchor and nexus for parallel universes?

(sorry layman here…but geeked on theory)

@Martin A. Curry: Time or space do not have superpositions in quantum physics, but – and let’s use relativistic quantum field theory – systems of particles can have. That is what makes the added quantum time dilation here.

To cross check subjective clock time’s direction, compare it with half-life times occasionally. Objectively, modern clocks are extremely good. Time estimated by instinct, or by importance, urgency, vacation time and so on are quickly revealed by occasional reference to a source of radioactivity. The inherent randomness is illuminating.

Relativity is objective (and so is quantum physics).

Once a laser beam (continous source) enters straight into a blackhole, it will turn to a circular path, so then that light course will change to a slower speed. I submit it is true because following a curve is a longer distance than a straight line. Is this a fair & accurate account? Or does light still travel at ‘c’ inside the blackhole instead of decellerate? Or do wavelengths assume or adjust positions simultaneously accordingly? How can light go faster or slower than, well, the speed of light, just because of blackholes intense gravitational force effect upon it? So is the speed of light the same in a blackhole as it is in the vacuum realm outside it of empty space?

We don’t know what happens inside a black hole. Essentially the basic solutions are variants of Schwarzschild’s solution [“Kerr–Newman metric” @ Wikipedia] and the consideration of quantum effects makes it an even more open question [Firewall (physics) @ Wikipedia].

The speed of light in vacuum of flaty space is the universal speed limit and the curved geodesics it follows in general relativity is straight lines for it – it has to be so according to relativity in order to preserve physical laws. I’m not sure if you are wondering how light can be indefinitely captures within the event horizon – but the simplified explanation that the Event Horizon Collaboration press conference on the M87* black hole image regaled us with is that of space streaming faster than that across the horizon. So it is analogous to a waterfall drop, and it is possible since the universal speed limit do not apply to space. (C.f. how the universe expands locally faster than the universal speed limit during the cosmological inflation era.)

I think the answer to many problems lie in how we understand the time concept. As we know in our macro-world we have a unit of lowest possible time length which is Planck Time (PT). Let’s think that in Quantum Mechanics this time unit is extremely smaller than our PT. Let’s call it QT. Now let’s think that we have a wheel of fortune with a black spot on its periphery. Assume that this wheel makes a complete turn in every PT. What we see in our macro-world is just a stationary black spot. But in fact in QM we can see the spot moving around the periphery and can be found in any point on the periphery at any given QT. In fact for an observer taking a photo in Quantum world at every QT, there will sometimes be a black spot on the photos changing its position in each photos while sometimes there will be no black spot in the photos (recall Heisenberg uncertainity). Thus a single photo taken at one PT corresponds to many photos taken at QT intervals each of which is equally real (Superposition). Hence, for an external observer in Macro world the situation is not dynamic, but for an internal observer in Quantum world it is dynamic and emergent, isn’t it? Moreover, the situation seems to be undeterministic for the external observer while it is deterministic for the internal observer. We can say that ”time is contracted and moves faster as we go down to quantum world” as opposed to time dilation. Further thinking on this subject brings us to the conclusion that ” Time behaves as a wave .The magnitude of its’ wavelength and frequency changes according to some parameters like velocity and associated mass. For example, near a black hole its’ wavelength increases and frequency decreases while the opposite is true at the quantum level”. I beleive this approach is consistent with both Quantum Mechanics and General Relativity.For a complete understanding of this new time concept of mine please refer to the link below.

https://www.iiste.org/Journals/index.php/APTA/article/download/52543/54303

ADDENDUM:

Testing the idea that Planck Time is not constant can be accomplished by serial measuremenst of Gravitational Constant ‘G’ using torsion pendulum experiments with the time-of-swing method. In this experiment when we increase the source mass exponentially, a slight increase in the measured value of ‘G’ will probably be obtained. Since Planck Time is calculated by the formula PT = (hG/2πc5)1/2 , an increase in ‘G’ will result in a slight increase in the calculated value of PT.

@Ozer Oztekin:

Possibly, but quantum physics is based on Planck units and so far there has been no problems with that. On the contrary, the article here describe how yet another result that may – if it works – be evidence that quantum physics and relativity continues to fit nicely together.

I couldn’t see any quantitative prediction in your paper, but I note that you claim we wi8ll see different Hubble rates in different volumes. But the cosmic background spectra show that the universe is homogeneous and isotropic to 10^-5 energy density, so that is apriori a hard sell.

Wikipedia list the journal publisher where your link goes to as predatory, so wouldn’t be science [“Category: International Institute for Science, Technology and Education academic journals” @ Wikipedia]. Also, that link is self promotion.

This discussion is great!! We must always question everything.we as humans are on the cuff of a renesanse in physics. Think about it,we all beleive in what newton and einstein taught us as absolute because they named their theories laws? No they meant for their theoreis to be expanded on by future generations. I mean really,how could guys in the 17th and early 20th century have all the answers especially with the limmited tech of the day its absurd. They did however discover anomalies that are really clues for us to know that there is way way more going on than we know. Clues such as time dialation. There is a whole new world of physics that we dont know about yet. Time dialation is the key to opening the new textbook on the truth. Space time,gravity, interdimentional travel,being able to brakedown living things to the atomic level and reatomize them without harm. Its just through the door. The next 20 years will blow are minds and put us on the path to becoming a type 2 civilisation and perhaps bring us togethr with are galactic brothers and sisters just waiting for us to grow up….

If you compare 2 distinct moving bodies relative to the same point of reference, then the relative difference between the two measurements is realistic even though still relative, not absolute. In the sense comparison between the Eastbound and Westbound 4 atomic clocks flown aboard commercial airplanes was realistic and it not only confirmed prediction of special relativity theory (SRT) but also showed its incompleteness. Similarly, instead of dropping balls from the leaning tower of Pisa, intercepting rays from Taurus A (the visible star of the binary star system Taurus) and then comparing the result with that of an atomic clock triggering radio waves (i.e. rays) intercepted by an atomic clock riding on a regular truck along the I-95 in the US up to Canada confirmed general relativity theory (GTR) but also showed its incompleteness, because the rays traversed the gravitational fields of our Sun and Earth, respectively, and their comparison contradicted Galilei, Newton and Einstein’s dismissal of other than radial effects of gravity (because “they would be too slight when measured on Earth”). You see, Einstein had not claimed that other than his [radial] effects of gravity are impossible but merely that they could not be detected back then. Einstein recognized possible presence of nonradial effects of radial gravity in his paper on GTR – see p.161 in the English translation by Dover Publ. quoted in my paper: [GWW] “Galilei was wrong…” in ILCPA (available online), but nowadays the effects have been measured and explained in [GWW] (see references therein) and reconciled in “On conjugate complex time II:…” – see CSF 11 (2000) 2001-2016.

The relativity of measurements is not condemning the results of (relative of necessity) measurements if both of them are compared with respect to the same point of reference, but almost all the guiding principles of past scientists have been exposed as either not quite complete or not quite correct, with notable exception of the purely radial experiment conducted by Vessot et al. – see “Flawed fundamentals of tensor calculus”, for instance. Relativity is not the problem, but screwed mathematics certainly is the problem – see the paper “On the Hafele-Keating experiment” whose theoretical part was cancelled by a successor of an Editor-in-Chief after it has already been accepted for publication by his predecessor.

@Jakub Czajko:

“intercepting rays from Taurus A (the visible star of the binary star system Taurus) and then comparing the result with that of an atomic clock triggering radio waves (i.e. rays) intercepted by an atomic clock riding on a regular truck along the I-95 in the US up to Canada confirmed general relativity theory (GTR) but also showed its incompleteness, because the rays traversed the gravitational fields of our Sun and Earth, respectively, and their comparison contradicted Galilei, Newton and Einstein’s dismissal of other than radial effects of gravity (because “they would be too slight when measured on Earth”)”.

I don’t know that you refer to, but all experiments to dat verify Einstein’s theory and no counterevidence is published in peer review [c.f. “Troubled Times for Alternatives to Einstein’s Theory of Gravity” @ Quanta Magazine]. The recent binary neutron star merger was pretty conclusive: “New observations of extreme astrophysical systems have “brutally and pitilessly murdered” attempts to replace Einstein’s general theory of relativity.”

Beall list the journal publisher where your link goes to as predatory, so wouldn’t be science [“List of Predatory Publishers” @ GitHub – links to the archived Beall list]. Also, that link is self promotion.

“In the early 1900s, Albert Einstein presented a revolutionary picture of space and time by showing that the time experienced by a clock depends on how fast it is moving — as the speed of a clock increases, the rate at which it ticks decreases. This was a radical departure from Sir Isaac Newton’s absolute notion of time.”

In special relativity, time dilation means that the time t of a moving frame observed in a static frame will become shorter i.e. t’ = t/Ɣ which clearly tells that only time becomes shorter, and never tells you that the rate of the clock slows down. Actually, the rate of the clock w relative to its own moving reference frame will become faster when it is observed in the static frame: w’ = Ɣw if you use Lorentz Transformation to calculate it. It is completely a wrong interpretation of relativistic time dilation. The reading of the clock such as the angle alpha of the arm relative to its own moving frame is alpha = tw, which will become alpha’ = t’w’ = (t/Ɣ)(Ɣw) = tw = alpha when it is observed in the static reference frame. That is, the clock time won’t change when you observe the clock in another inertial reference frame. Therefore, clock time is still absolute in special relativity, completely different from relativistic time t which becomes t’ when the reference frame is changed. As we always use clock to measure time in real observations, clock time is the real physical time, and thus relativistic time is just a fake time (i.e. a mathematical time without physical meaning).

People may argue that we have already found clocks become slower when they are moving. Yes, it is possible but they are all absolute changes of the frequencies of the clocks, nothing to do with relativistic time dilation. We know a pendulum clock will run more slowly on the moon, but never say the time on the moon is slower. A tree in the tropical area grows faster than in the artic area, but never say tropical time goes faster. The faster a mechanical clock with its balance wheel exposed to the air moves against air, more slowly it will tick. Shall we claim it is the effect of time dilation? No, never. It is the same that we should not say that it is time dilation when an atomic clock ticks more slowly at a higher speed relative to aether.

@Xinhang Shen: I don’t know that you refer to, but all experiments to dat verify Einstein’s theory and no counterevidence is published in peer review [c.f. “Troubled Times for Alternatives to Einstein’s Theory of Gravity” @ Quanta Magazine]. The recent binary neutron star merger was pretty conclusive: “New observations of extreme astrophysical systems have “brutally and pitilessly murdered” attempts to replace Einstein’s general theory of relativity.”

Also, what do you mean by “arm” of the clock? If you use Einstein light clock oscillators you can rotate the light beams relative to each other to arrive at his original analysis – which holds up in experiments as per above.

“Nice comments so far, that is refreshing!”

But returning here, the last three comments all criticized relativity instead of discussing the article, in two cases linking to non-science predatory sources (and for the purpose of self promotion). Oy!

I know that the number of predatory journals explodes, but part of the reason is that those who want to publish either don’t do their homework or realize that their seeming pseudoscience cannot be published. It is not the task of science site commenters to have to vet links for publishers, at best we should be able to sit down and read a science paper for its putative results.

And of course, since vanity/predatory press bamboozle money from various sources, it is both morally and economically problematic to use them/be used by them.

… Some would ask, “why would Albert be so in distrust with quantum theory, when he set one of the corner stones with his work”. The reason for that is that Albert was kind of kin friend of the thing called determinism and that the reason why he was so sceptical about theory, even though there was more than plenty of evidence to support the theory, is that he was not able to convince him self how the non deterministic system would give emergence to a deterministic system. One example would be a Gaussian distribution, or dice toss you will never know the number that will one get in another turn, however it is possible to say how often you will get each number, ….