1. Question
The questions that always stay in my mind:
- How is time defined?
- How is time measured?
- What’s the origin of time?
2. Thoughts
How is time defined?
A measurement of motion and movement.
- If a system is unchanging, it is timeless
Why can’t time go backward?
- Due to second law of thermodynamics, in a isolated system, the entropy would only increase
How is time measured?
Time is not same everywhere, time depends on reference or observer.
What’s the origin of time?
Only for the universe, there is a beginning. (Big Bang)
Rely on the definition, no definition before the time
3. Universe?
Quantam field
- Generate from void
Equation can’t do the magic, why these laws?
4. One Second
What is 1 second? the time that elapses $9.192631770\times 10^9$ cycles of the radiation produced by transition between two level of cesium-133 atom
Why such an odd number? 9.19.. to mimic the old standard so that old system don’t need to be recalibrated.
Why cesium? unchanging physic law
5. Takeaways
No answers, probably never.
Rely on the definition and perception