# Real objective time clock/s?

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• timeuser84
timeuser84
hi, new hear, not sure where to post this question. this might sound like a silly question but is there any clocks that can measure real accurate objective time meaning outside of are minds/head? and not measured based on theoretical projections or inner math as I call it. I am thinking atomic clocks do but that is just a guess.

## Answers and Replies

jerromyjon
I am thinking atomic clocks do but that is just a guess.
Everything, including atomic clocks, are subject to time dilation. Google it...

rootone
rootone
real accurate objective time
Relativity predicts that there is no such thing as objective time in a universal sense;
It proposes that subjective time is relative to the 'reference frame' of the thing being observed and that of the observer.
Yes that is pure math, but the accuracy of that prediction has been well tested .. using atomic clocks.
Here's a description of one of the first attempts to do that.
https://en.wikipedia.org/wiki/Hafele–Keating_experiment

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MarekKuzmicki
Mentor
objective time meaning outside of are minds/head
That is the only time that is measured. I don’t even know how it would be possible to measure time inside someone’s mind.

russ_watters and Vanadium 50
Mentor
but is there any clocks that can measure real accurate objective time meaning outside of are minds/head?
"Objective" and "accurate" are different things. Every clock measures a real objective time (the generally accepted term is "proper time", and you'll see it in many discussions of relativity) but some clocks do it more accurately than others. An atomic clock is much more accurate than a sandglass, but they're both providing an objective measure of time passing, just as a laser rangefinder measures distances more accurately than a wooden ruler but there's no doubt that they're both measuring distance.

Gold Member
That is the only time that is measured. I don’t even know how it would be possible to measure time inside someone’s mind.
Humans have a pretty good body clock that's as accurate as we need. It's not Quartz accuracy but we still have it. We can also train our brains to get pretty accurate 'perfect pitch' for musical performance - to well within a semitone ratio (<1/21/12)

Dale
timeuser84
thanks all for answering my questions however I have one more question. The reason I posted this question is because I did not know whether the real facts about the clocks that I already have measure objective time or if my clocks measure pseudo/pseudo facts/bs time which is what I meant by theoretical projection/inner math so I wanted to make sure they measure the real time and did not want to be fooled by this time trickery or waste time based on it. If my clocks do not measure objective and/or accurate time and may be pseudo or off a bit then I will want to fix that. if my clocks are pseudo and are messed up beyond repair then I would look for the type of clock of my preference(measuring objective time and accuracy) to purchase. As Nugatory stated, Objective time and accurate time are two different things so because of that I would much rather have a clock that measure objective time over accuracy if I cannot find one that has objective and accuracy. I have a labtop clock which is a few or more hours off official time in my erea, a digital clock which Is over a few years old where the time can only be set manually, another clock in my smartphone Samsung galaxy and two hand wrist watches that don't work or the battery's are dead.

So My question is what is the best and most up to date version of the type of clocks based on my preference as of the current times?

Gold Member
@timeuser84 If you want to know the state of the art in timekeeping (I am not sure whether or not that's what you are actually after - but there is some good stuff there anyway) you could try this link from the National Physical Laboratory (UK)

Mentor
another clock in my smartphone Samsung galaxy
They all measure objective time, but the smartphone one is probably the best since it should be updated with a network time standard.

Gold Member
They all measure objective time, but the smartphone one is probably the best since it should be updated with a network time standard.
The time that the master clock at the source of Network Time generates only applies to the time at that actual location. Every foot away from that clock introduces a lag of 1ns even if the time signal is transmitted at the speed of light. If you know the delay from the source clock to your 'slave' clock, you can get the times to read 'synchronously'. But what does that mean? It can only mean that a person who is equal distance from both clocks will receive the second ticks at the same time by his personal clock.
Using a network line the Internet introduces a lot of uncertainties into when the actual instant of the occurrence of, say 12.00.00 hours at the master clock because such data has to take its turn in a queuing system with all the other data and the delay is different from minute to minute.
There are standard time sources which are broadcast by low frequency radio and they are probable the most consistent. We have an alarm clock that receives a radio signal which keeps the clock's crystal oscillator from long term frequency drift. See MSF time signal. That's pretty reliable as long as you check that the clock receiver is actually receiving the signal, which is very low level in many parts of the UK.!

Dale
Mentor
They all measure objective time, but the smartphone one is probably the best since it should be updated with a network time standard.
The computer should be too -- it needs to have its time zone manually set though.

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Gold Member
I have a very different view towards objective time. I think a time keeping device such as a smartphone will definitely not be able to keep accurate time in relation with the rest of the world.

First of all, there cannot be simultaneity, two clocks separated by space cannot be connected such that their times are exactly the same. If they are connected to a network of devices and then adjust their time to the rest of the devices, they are not recording real time, they are simply "messenger clocks" giving you information from another clock.

Second, the entire concept of objective time is arbitrary. There is not time. For two clocks to be synchronized in time and to give a precise reading of time, they must be in the same place and they must be the same clock. Time is a dimension which is just like space. Us three-dimensional beings can only move through time one way, but we can go faster or slow down. At some point we could just go back in time. But, while we are changing our time, other people's time is constant. Time is not a fixed calculation of movement. It is like velocity or acceleration. It is like asking "What is the velocity and of everything". Everything has a different velocity thus this cannot be answered. Similarly, everything has a different speed of time, thus we cannot ask the objective time.

Objective time cannot be achieved, but we can give time in units of seconds and come up with smartphones and atomic clocks, but alas, there is no "real accurate objective time".

sophiecentaur
Gold Member
I think a time keeping device such as a smartphone will definitely not be able to keep accurate time in relation with the rest of the world.
Contributors to this thread have clearly a range of different models in their heads and hence the comments and expectations are different. That NPL link discusses all these problems so I recommend reading for everyone, some basics about time standards.
Absolute time is not really a valid concept because you can only have two clocks with the same time if they are sitting right next to each other. Only then will they appear to have the same time for all observers in all locations. If one is nearer to the observer then its displayed time will appear to be earlier than the more distant clock. Time is always relative. This problem goes right back to the early days of the railway system when they wrote the timetables and the local time on the station clock was set by when the Sun passed overhead (Noon). The apparent journey times for East West journeys was less than for West-East journeys. Until then, time relative to local Noon was the most important thing to most users (except navigators, of course). Nowadays, we use GMT as the standard in the UK (or Universal Time - UT etc) but, instead of the rotation of the Earth messing it up, it's the speed of light (radio synchronisation signals) does the same thing to a far lesser amount.
There is an essential difference between time and frequency.
A smart phone (or even the most sophisticated Rubidium Activated Caesium Clock) will have a particular accuracy / error on its basic oscillators frequency, relative to the frequency of a basic oscillator standard in a reference clock, somewhere in the world. (Unless there are significant relativistic effects to be considered). The 'time', as specified by the hands on that reference clock needs to be corrected for if you are, for instance, doing astronomical measurements in two different places on the Earth and you need to agree 'when' something astronomical happened.
But. as I commented earlier, you can't rely on taking your time reference from an Internet Source (iPhone display) because the information arriving at your local computer can have taken different paths from time to time - differing by a large chunk of one second - which I don't think you could ever call "objective'.
I have given up trying to set the sweep second hand on my fairly expensive analogue watch because the only sources with implied <1s precision are very likely to be much more than 1s adrift over the day.

lekh2003
_PJ_
The biggest barrier to any concept of 'absolute time' is relativity. As soon as one clock moves relative to another, then each will have a different measure of time but NETHER WILL BE MORE "correct" than the other.

Gravity also causes this disparity since it can change the shape of a "straight line" which light follows invariantly in a set time. This speed of light is the arbiter of causality.

What we can do, though, is take an approximation across the entire Earth that all external influences (such as motion of the Earth around the sun and the gravitational pull of the sun, moon etc. - are all ignored under an assumption they are equal across every clock on the earth. The only consideratons taken into account, then, are the distance of a clock from the centre of the Earth and its motion relative to the centre of the earth.

Organisations such as NIST maintain an incredibly accurate atomic clock system* which takes an incredible number of factors into account (even introducing leap seconds every so many years to adjust for astronomical factors etc) such as that the length of a day is increasing (as Earth's angular momentum gradually is transferred away)
Other institutions around the world coordinate with this baseline and their own position relative to NIST source and the centre of the Earth's gravity - as well as adjusting for the relativistic separation, in order to provide a coordinated time around the globe.
This is known as UTC and whilst based on earlier timezone models is (despite most simplified common application) not solely restricted to a basic 15 degree quantisation of hourly offsets - if you're between two such offsets, the precise UTC offset for your locale will actually be calculable to the minutes, seconds and fractions of seconds, but for general purpose, (such as coordinating trains etc. and the practicality of not having to change your watch every time you travel even a short distance) this is not used. The hourly quantum leaps of timezone offsets serves the purpose of ensuring a coordination and translation of local time.

I think a huge aspect to the question of time accuracy and reliability has to be "why"- Y which I mean, one can undersstand the importance of accurate timing when it is time that is used (as it can be measured more accurately) in signals to/from satellites in determining GPS location (so that car navigation can be accurate to scales of a metre, which is clearly safer and practical) - but for everyday human usage (by which I mean, where people are using a time measurement directly, not by proxy of a satellite system) - Almost every digital clock can provide reasonable accuracy to a hundredth of a second. So this is sufficient for experimental timings and more than sufficient for races (the error margin of reaction times to pressing the stopwatch button far outweighs this level) - so arguably, for simply "telling the time" accuracies of even a minute or two are far more than sufficient for most general purpose.
The issue in this comes when clocks "lose" or "gain" 'time' over (sorry) time. When even ignoiring the nanoseconds of relativistic dilation and apprximating the hours of offset between Cairo and Beijing - Despite my clock saying it's 15:45, I end up late for my appointment - Therefore, I expect that this is the real pertinent point of consideration wrt this thread - how to ensure the reliability of ones personal clock in synchronisation with the "established" local time -
Well of course, every clock is still unique. At home my kitchen clock (cheap batetry operated thing) is always different to the Front Room (aesthetic pendulum analogue) and no doubt, the neighbours have also completely different times on all their clocks. Who's right?
The closest answer can only then be, the NIST clock, as synchronised to the local clock's position.

This synchronisation is key, and internet-connected devices will generally include such a synchronisation feature. However, not all such devices necessarily have accurate geolocation information - my desktop PC for example, does not, so instead, the timezone setting is used. But that's fine, because If my appointment is at a place within the same timezone abut over 8 degrees arc away, I wouldn't want my clock to be half an hour slower/faster than theirs.
If a clock does not have the facility for internet or other synchronisation with NIST or such providers, then a more manual approach is needed. The speaking Clock service exists for this purpose, but is now a little archaic. Otherwise there is no comparison for accuracy. The best approach is to synchronise with any ther device that you can be confident HAS been synchronised with NIST. The alternatives are sychronisation with any other clock for which none can claim to have any "authority" on accuracy or correctness.

Given it's unlikely that one would ignore the gradual drift of a clock accuracy for so long that it became comparable to an hour difference from other local clocks, for the most part, the NIST synchronisation is required only to maintain the minutes. Timezones fix the hours and if your clock includes a calendar, then it's a good chance that asking anybody can reliably tell you the day (at least within two on a weekend ;) ) and the month is pretty much assured!

*Atomic clocks are accurate in that the definition of a second is exactly given by the frequency of emission from Caesium. That is the clock is measuring time in the same way that the units are actually provided. Although this doesn't make them any more correct than any other clock, they will always give the exact numbre of seconds of duration.
It should also be noted that what are often marketed as 'atomic clocks' are simply digital clocks that regularly (no pun,sorry) synchronise with an official provider which relates a signal from an actual atomic clock.

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Homework Helper
if you're between two such offsets, the precise UTC will actually be calculable to the minutes, seconds and fractions of seconds,
The current UTC time is what it is. It is the same no matter where you are on the globe. It does not change depending on your time zone or on your position within a time zone. Synchronization between UTC clocks effectively assumes a non-rotating Earth-centered inertial frame.
The only consideratons taken into account, then, are the distance of a clock from the centre of the Earth and its motion relative to the centre of the earth.
The relevant factor would be altitude relative to the geoid. It is my understanding that the combination of velocity-based time dilation (special relativity) and gravitational time dilation (general relativity) is identical for clocks positioned at sea level, no matter where they are located on the globe.

Gold Member
That is the only time that is measured. I don’t even know how it would be possible to measure time inside someone’s mind.

There is a psychological arrow of time...

_PJ_
The current UTC time is what it is. It is the same no matter where you are on the globe. It does not change depending on your time zone or on your position within a time zone.
Sorry you are correct in that UTC is the time exactly on the Prime Meridian - what I was referring to is calculating ones local coordinate time from the UTC. Also my reference to earlier timezones with respect to the application of consideration of local time against the UTC base.

The relevant factor would be altitude relative to the geoid. It is my understanding that the combination of velocity-based time dilation (special relativity) and gravitational time dilation (general relativity) is identical for clocks positioned at sea level, no matter where they are located on the globe.
The latitudinal/longitudinal coordinate position determines the local time offset, which is what the next paragraph addresses.

Homework Helper
The latitudinal/longitudinal coordinate position determines the local time offset, which is what the next paragraph addresses.
Local time offset is a choice of the local governing body. Or of the traveler who chooses whether to adjust his wristwatch. Normally it is chosen so that noontime occurs around 12:00 pm, but not always.

Mentor
The biggest barrier to any concept of 'absolute time' is relativity
Except that the OP is not asking about “absolute time”. He is asking about “objective time”, which he has defined simply as time measured outside of our mind. All the clocks he mentioned are objective in that sense.

differing by a large chunk of one second - which I don't think you could ever call "objective'.
That is still objective (outside of the mind). Just not very accurate by modern standards.

Gold Member
Except that the OP is not asking about “absolute time”. He is asking about “objective time”, which he has defined simply as time measured outside of our mind. All the clocks he mentioned are objective in that sense.

I think that _PJ_ is using the wrong term, but the question still allows for the discussion of relativity, and the basic idea behind the post is sound.

Mentor
I think that _PJ_ is using the wrong term, but the question still allows for the discussion of relativity, and the basic idea behind the post is sound.
Sure, the idea is sound, it is just not what the OP is asking about. Nothing from the OP indicates any concern with relativistic effects, and he did not even post in the relativity forum.

_PJ_
Local time offset is a choice of the local governing body. Or of the traveler who chooses whether to adjust his wristwatch. Normally it is chosen so that noontime occurs around 12:00 pm, but not always.
Yes, and this doesn't reflect 15 degrees the IDL goes around islands and there are some 30 and 45 minute 'offset timezones'.

Wherever there is a clock, that clock will have a local time. In any circumstance of coordination with any other clock, there is required to be some consideration of an offset between the two. Politically, this is, as you say, designated by nations independantly but agreable to the UTC standard. However, this is not the only, nor authoritative notion of 'local time'.

For example, and as I was referring to in the section you quoted which describes how different position relates to NIST standard, the "Local Time" for a GPS device is independant of whatever the 'wall time' may be for that political region and relies on calculations based on more precise measurement of position.

Gold Member
Sure, the idea is sound, it is just not what the OP is asking about. Nothing from the OP indicates any concern with relativistic effects, and he did not even post in the relativity forum.

Even if the OP initially had no concern with relativistic effects, the question asked by the OP is strongly linked with relativity. Relativity discusses objective time thoroughly. Even if the OP has not mentioned relativity, it does not discredit it's value as an answer.

_PJ_
I used the term "absolute time" because the OP alluded to an "accurate and objective time" for which I made a best guess as to what they were trying to ask, rather than accept what they had literally posited. I understood the OP was trying to ask about something resembling an implication of "proper time" that was universal - which I peronsally chose to describe as a concept as "absolute time" because I had no other words to describe such a concept.

Mentor
Even if the OP has not mentioned relativity, it does not discredit it's value as an answer
I made a best guess as to what they were trying to ask, rather than accept what they had literally posited.
Sure. I have done the same thing many times myself in the past. I understand the temptation.

I just want the OP to be aware as he may be confused about the responses that he is getting now.