Is it even theoretically possible for a perfect clock to exist?

Question

I have heard that even atomic clocks lose a second every billion years or so. That raises the question, is it even theoretically possible for a perfect clock to exist, one that never gains or loses time?

A different point of view would be to say that there are many perfect clocks, and it is just man's interpretation that is imperfect. An atomic clock vibrates at a certain rate; it is that rate that is correct, not our imperfect measurement of it. The earth goes round the sun in exactly one year; it is our clocks and calendars that are incorrect, the earth turns in exactly 24 hours, regardless of how we measure it. Human clocks are merely attempting to measure something that occurs in nature. — foolishmuse, Feb 04 '21 at 23:20
A clock is a measurement device. ALL measurement devices have a finite precision. — David White, Feb 04 '21 at 23:46
@foolishmuse, Re, "The Earth goes round the Sun in exactly one year." Are you defining the word "Year?" Or are you claiming that the Earth-Sun system is a perfect clock? — Solomon Slow, Feb 05 '21 at 00:07
@foolishmuse, Re, "the earth turns in exactly 24 hours." Actually, that's not true--at least, not if "hour" means exactly 3600 international seconds. https://en.wikipedia.org/wiki/Day_length_fluctuations — Solomon Slow, Feb 05 '21 at 00:10
@SolomonSlow What is the original definition of one year; the time it takes for the earth to circle the sun. What is the original definition of one day; the time it takes for the earth to complete one rotation. What is the original definition of 1 second: 1/60th of 1/60th of 1/24th of one day. Yes, these amounts very from day to day and from year to year, but that's the real world. I didn't put this as an answer because I know that it doesn't match modern thinking. But any real clock would only match what occurs in the real world. — foolishmuse, Feb 05 '21 at 16:41
@foolishmuse Re, "...any real clock would only match what occurs in the real world..." What use is a clock that always says some particular process (e.g., one rotation of the Earth) always takes exactly the same amount of time? The whole point of clocks is that different processes take different amounts of time. And different instances of the same process process (e.g. different rotations of the Earth) can take different amounts of time. Having a highly accurate clock--one that does not depend on the things that you're trying to measure--is what enables you to measure and compare them. — Solomon Slow, Feb 05 '21 at 18:01
@SolomonSlow You have to start thinking in relative terms (this is a physics forum). Everything in this forum changes according to your relative position. Once you learn how to use a sextant for navigation, your whole perspective on time changes. — foolishmuse, Feb 05 '21 at 18:51

score 4 · Answer 1 · answered Feb 04 '21 at 23:01

The words "perfect" and "exist" are not compatible. The only way we can imagine perfect things is in our imagination, not in anything that exists. For things that exist, we can ask how close they are to being perfect, but even that question will not have a perfect answer. The best we can do is to estimate how close they are to being perfect. Losing 1 second in a billion years is pretty darn close to being perfect (since it is 1 part in 31,557,600,000,000,000) but it is not perfect and nothing physical can ever be perfect.

Solomon Slow · Accepted Answer · 2021-02-05T01:00:40.447

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I have heard that even atomic clocks lose a second every billion years or so.

That would be a small misunderstanding on your part. The second now is defined by atomic clocks. So, if all atomic clocks were consistently slow, then that would mean that the definition of a second was wrong... by definition.

That doesn't make sense.

What you read probably said that an atomic clock can not be regulated to better accuracy than plus or minus so-many seconds per billion years. That is to say, if you built an ensemble of atomic clocks, and you let them all run for a billion years without ever correcting them, then you could expect their counts to differ by some small number of seconds at the end of that time.

edited Feb 05 '21 at 01:00

answered Feb 05 '21 at 00:18

Solomon Slow

14,534

Primary atomic clocks are not regulated or corrected. – Massimo Ortolano Feb 05 '21 at 11:23
@MassimoOrtolano Can you expand that comment? My understanding is that there's still measurement uncertainty; so the atomic frequency is accurate and precise (because that's how time units are defined), but actually measuring it in an atomic clock is not. Also I think the "without ever correcting" in the answer refers to cross-calibrating different clocks when their measurement uncertainties accumulate, no? – Stephan Matthiesen Feb 05 '21 at 13:34
@MassimoOrtolano, That would be a deliberate choice, not a physical necessity. In principle, any clock can be adjusted if its owner chooses to do so. What procedures actually are followed by the owners of the various clocks whose average define International Atomic Time is beyond my knowledge. – Solomon Slow Feb 05 '21 at 13:48
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Solomon, I made the remark because it's actually within my knowledge: in general, they really neither regulate nor correct primary clocks (some corrections are applied by evaluating certain systematic effects, e.g. the relativistic effect due to the altitude). @Stephan There's no cross-calibration either, but the explanation would be really too long for comments (and I'd hardly find the time for an answer to a question). Audoin's book which I referenced in this answer is a good source of information about these topics. – Massimo Ortolano Feb 05 '21 at 14:02
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@MassimoOrtolano Perhaps my comment was unclear. What you say is what I already know. This wasn't what I meant, and it's not how I understand Solomon's answer. To clarify: Do you agree that if we build two or more atomic clocks and let them run for a billion years, they will differ by some small amount? This will not be relevant for any human timescale and the point was not whether clocks in practice are corrected or not, but that in principle there are will be uncertainties. – Stephan Matthiesen Feb 05 '21 at 19:59
@StephanMatthiesen First let me make a clear distinction, which is frequently a source of confusion. When it comes to time, there are two elements at play: clocks, better called frequency standards, which are devices generating a standard frequency or time interval, and time scales which are procedures to cumulatively count events generated by clocks (this count depends on the phase of the clock rather than the frequency). – Massimo Ortolano Feb 05 '21 at 20:24
Clocks differ by the generated frequency and this difference is due to two elements: one is the bias caused by systematic effects which determine the accuracy of the clock (the second is defined with unperturbed atoms at rest, and this cannot be realized in practice), the other is the instability of the clock due to various noise sources which cause instantaneous fluctuations in the frequency. When the popular press uses the expression "x seconds in billion years", it typically refers to the error that one would have in a time scale driven by such a clock and due to just its instability. – Massimo Ortolano Feb 05 '21 at 20:25
@MassimoOrtolano I'm not referring to the "popular press" but actually have a degree in physics. What you write is all well-known and interesting, I just don't see that it helps to answer the OP's question or how it contradicts the answer given by Solomon. I don't doubt your knowledge, it just seems we're talking about different things, so I guess I'll leave it at that. – Stephan Matthiesen Feb 05 '21 at 22:30
@StephanMatthiesen This was just the beginning to be sure to start with common ground, and as I said I don't have much time to spare, which means I'd have added further details later on. But since you don't have patience, let's stop here. – Massimo Ortolano Feb 06 '21 at 01:54
@MassimoOrtolano Why don't you write all this as a proper answer? Comments are not meant for extended discussions. By the way, I'm not the original poster, I just wanted to clarify how your comment helps to answer the original question. – Stephan Matthiesen Feb 07 '21 at 10:15
And, such ensemble would be a more perfect clock than one individual clock, because you can average over them. – Anixx Apr 12 '21 at 19:44

score 2 · Answer 3 · answered Feb 05 '21 at 08:40

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Well, there is no concept of absolute time or a perfect ' tick tock ' in the universe. Phenomena happen at their own rate.

You can't quantify their 'perfection'. You can quantify the errors you made while measuring their physical aspects.

answered Feb 05 '21 at 08:40

Magnetic Monopole

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score 1 · Answer 4 · answered Apr 12 '21 at 19:52

Imagine a totally perfect clock. It measures the time in the place where it is situated. Its own proper time. But due to general relativity the speed of time is affected by nearby objects, gravitational fields, spacetime curvature, speed of motion and gravitational waves.

The ideally perfect clock would look not that perfect for anyone who is located in a different place, surrounded by different bodies that curve the spacetime, and moves around at different speeds.

So, even ideally perfect clock would be not that much useful because it would measure its own proper time, in its own reference frame and in its own place relative to other objects, which is surely different than the proper time of any other object.

score 0 · Answer 5 · answered Feb 05 '21 at 06:31

To say that something is perfect, accurate or absolute, is in itself a lie if we consider the realm of our cosmos being governed by the laws of physics - be it classical, modern, or others. The most convenient way to say is that nothing is absolute in this real world ( ha! I know that the speed of light is constant in vacuum. But, yes, the truthfulness is just unachievable ). Even space and time is not just, because we know the instances where space-time is just not as accurate as it seems to be. The theories and their related phenomena, of length contraction, time dilation, red/blue shift in macro physical words and gravitational lensing, gravitational waves and much else more in the quantum level, suggests and portrays a world that we live in as something of a ever changing and ever revealing Pandora's box.

score -1 · Answer 6 · answered Apr 12 '21 at 19:22

It seems as though you are asking if a "clock" can exist that isn't impacted by relativity/time dilation. At the moment, nothing we can observe in the universe is free of time dilation. We would need to be able to observe or measure a property of the universe or particle that does not suffer any impact of time dilation.

Unfortunately, there are few possible extra-relativistic properties we can even indirectly observe in the universe (quantum entanglement being on the short list). We would need to have a better understanding and direct measurement capacity of such a property to devise such a "perfect" time dilation free measurement or apparatus.

Is it even theoretically possible for a perfect clock to exist?

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