Time Calculator
Comprehensive Time Mathematics
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Add or subtract time from a given starting point.
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Compute expressions formatted as 1d 2h 3m + 4h - 50s
Understanding the Measurement and History of Time
Like other numbers, time can be added or subtracted. However, due to how time is defined, there exist differences in how calculations must be computed when compared to decimal numbers.
Concepts of Time in Physics and Philosophy
Aristotle
The ancient Greek philosopher defined time as "a number of movement in respect of the before and after." He believed time was a measurement of change requiring continuous motion in an infinite universe.
Newton & Leibniz
Newton argued for an imperceptible "absolute time" that flows without regard to external factors. Leibniz, contrarily, asserted "relational time," believing time only makes sense as a way to sequence observable events.
Einstein
Albert Einstein introduced "spacetime" as a connected concept. He posited that the speed of light is constant, meaning time is relative and moves slower for objects moving faster through space.
How We Measure Time
There are two distinct forms of measurement typically used today to determine time: the calendar and the clock. These are based on the ancient Sumerian and Babylonian sexagesimal numeral system, which uses 60 as its base.
Base 60 is used because it is a superior highly composite number with 12 divisors (1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60), meaning calculations that divide an hour into halves, thirds, quarters, and fifths always yield whole numbers. The Egyptian civilization is widely credited as being the first to divide the day into smaller parts via sundials, later standardized into 24 equinoctial hours by Greek astronomer Hipparchus.
Historical Timekeeping Devices
Early devices for measuring time were highly varied, usually intended to divide the day to regulate work or religious practices:
- Water Clocks (Clepsydra): Regulated flow of water. Considered the most accurate clocks of the ancient world.
- Sandglasses (Hourglasses): Appeared in the 14th century. Later calibrated by mechanical clocks for measuring specific periods.
- Pendulum Clocks: Created by Christiaan Huygens in 1656. The first clock regulated by a natural period of oscillation.
- Atomic Clocks: The modern standard. Uses an electronic oscillator tracked by cesium atomic resonance. The SI unit of time, the second, is calibrated based on this radiation.
Key Takeaways
- Sexagesimal Heritage. Our timekeeping relies heavily on a base-60 mathematical system pioneered thousands of years ago.
- Time is Relative. Time measurement acts differently depending on one's observational frame of reference relative to the speed of light.