Question

The main reason this question occurred to me is because a lot of conclusions, often coming from Big Bang theory, are claimed about time in a context that not only seems non-Relativistic (such as the objective time since the Big Bang), but in reference to past times when the atomic structures & stable atomic environments didn't even exist for an atomic clock to even theoretically exist there & then. So it seems these highly accepted Big Bang conclusions would require an SI definition of time that's rooted in a context in which an atomic clock could actually be theoretically used to measure time during the entire unfolding of the Big Bang.

Answer 1

Time measurement related to the Big Bang is based on modern physics, especially relativity and quantum mechanics, which can theoretically measure time without the need for atomic structures.

Experiments have confirmed aspects of relativity such as time dilation, and concepts like the Cosmic Microwave Background help place events on a cosmic timeline.

Step-by-step explanation:

The concern raised pertains to the concept of time measurement during the Big Bang and the progression of the universe, in the absence of atomic structures needed for atomic clocks.

Classical physics provides a framework for understanding everyday phenomena, but modern physics, which includes the theory of relativity and quantum mechanics, is needed to explain phenomena at extreme scales such as the early universe.

Time dilation, as predicted by Einstein's theory of relativity, has been experimentally confirmed through various tests such as the use of atomic clocks at different altitudes and velocities.

Moreover, the concept of time as we measure it today is rooted in the theories and experiments of modern physics, which can be applied retrospectively to model the history of the universe from the Big Bang.

For example, the Cosmic Microwave Background provides evidence of the universe's age, and studies suggest that there may be a smallest measurable time interval, beyond which time may be 'grainy' due to quantum fluctuations.

This suggests that even without atomic clocks present, time can still be theoretically measured and understood within the contexts provided by modern physics.