If we have such a clock and we use it to travel to a back hole and stay there for say 24 universal hours and we come back to the earth, is the passed time exactly the same on earth according to that clock?

I am trying to understand whether the time we refer to in physics is somehow related to the life/vibration/movement of the quantum particles.

Some people reported my question as off-topic. This is not off topic and I'm not talking about a new theory of my own!! I am trying to understand the concept of time in physics.

People who keep talking about my hypothetical clock they don't understand my question. It's not about the clock, it's just a hypothetical clock to understand something else.

My question is about having a clock with different rate as opposed to atomic clock.

So if an astronaut and his brother have the same type of clock, would they still experience different time relative to each other?

I understand that the astronaut is made off cells which is made off quantum particles so yes his body will definitely experience a slowed-down time relative to his brother.

However, my question is more about the measure of that time. So for example, we said every 60 oscillation of pendulum is 1 minute. Now this measurement can vary according to relativity in different location or at different speed, so now if our clock is not based on the local elements, would that be used as a universal clock (regardless of what the body of the astronaut is experiencing)?

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    $\begingroup$ What do you mean independent from the laws of physics? $\endgroup$ Sep 4, 2020 at 5:55
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    $\begingroup$ A clock that is independent from the laws of physics can do anything it wants to. $\endgroup$
    – WillO
    Sep 4, 2020 at 6:03
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    $\begingroup$ Also: Your clock is going to have to be pretty magical indeed if it registers the time passed on earth while it was off vacationing at a black hole. $\endgroup$
    – WillO
    Sep 4, 2020 at 6:06
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    $\begingroup$ Also: There was relativity before there was quantum physics, so no, the time we study in relativity can't depend on anything to do with quantum particles. $\endgroup$
    – WillO
    Sep 4, 2020 at 6:07

1 Answer 1


The concept of time in physics originates with the observation that certain physical processes are repetitive. In the history of the measurement of time a series of these repetitive processes have been used as increasingly accurate and regular benchmarks. In the first instance it was the cycle of day and night, followed by the beats of a pendulum, the oscillations of a quartz crystal, and most recently the frequency of electromagnetic waves emitted by electrons moving between energy levels in an atom. A clock is simply a device that measures the passage of time by counting the repetitions of one of these physical processes (so a calendar is a type of primitive clock, just a very slow and not very precise one).

All of which means that you cannot have a clock that is “independent from the laws of physics”.

It is, of course, possible to build clocks that run at different rates and measure time in different places. A clock on a spaceship that adjusted its rate according to the spacecraft’s speed relative to earth (as measured by inertial guidance or Doppler shift) could keep track of “earth time” rather than local time in the spaceship. Even simpler, you could synchronise a clock with time signals sent from earth, adjusted for the distance they have travelled. Keeping track of earth time in a spaceship is not conceptually difficult, but it is not telling us anything special either.

  • $\begingroup$ Thanks! So let's say that we have a clock that is based on the orbit of earth around the sun, so one complete orbit is one minute and let's say that we have this device that magically instantly updates all the clocks connected to it (for example using entanglement or something) now if an astronaut near a black hole uses this new clock and his brother on earth uses another of this new clock and they sync their time then the astronaut stays there for 2 min and instantly comes back to the earth, would the time that passed for both be two min? Sorry it's a bit hard to put it in words $\endgroup$
    – xbmono
    Sep 4, 2020 at 10:00
  • $\begingroup$ @xbmono Both clocks are measuring “earth time”. But for the astronaut near the black hole, local time is passing more slowly than earth time, and if he had an “ordinary” clock that measured local time then he could measure the difference. Just because he has a device that measures earth time does not change the rate at which time passes in his locality. $\endgroup$
    – gandalf61
    Sep 4, 2020 at 12:18
  • $\begingroup$ @xbmono : If you have access to a magic clock, I suggest that you ask it for unlimited wealth, then kick back, relax, and stop studying physics, which, if magic clocks exist, is all wrong anyway. $\endgroup$
    – WillO
    Sep 4, 2020 at 16:35
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    $\begingroup$ @WillO If you are after fun, I suggest you go somewhere else. I already mentioned a "hypothetical" clock, so my question is NOT about that clock but you kept talking and mocking about that. If you don't like a question, then please do not answer it $\endgroup$
    – xbmono
    Sep 6, 2020 at 22:24
  • $\begingroup$ @gandalf61 Thanks so much for your time. Unfortunately some people here are so arrogant they think if a question doesn't make sense to them, then they have rights to mock it or make fun of it or vote it down. You patiently replied my question. This question marked as off-topic... I can't believe it. I am not providing a new theory or something I am just trying to understand this concept $\endgroup$
    – xbmono
    Sep 6, 2020 at 22:30

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