Time Calculator

Time Calculator

Calculate time differences or add/subtract time durations

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🕰️ Understanding Time: From Ancient Views to Atomic Clocks

📏 Units of Time

Time is measured using a wide range of units:

  • Millennium: 1,000 years
  • Century: 100 years
  • Decade: 10 years
  • Year: ~365.242 days (Common: 365; Leap: 366)
  • Month: 28–31 days (e.g., February has 28 or 29)
  • Week/Day/Hour/Minute/Second: Down to milliseconds, microseconds, nanoseconds, and picoseconds.Time Calculator

🧠 Philosophical Concepts of Time

🔸 Aristotle (Ancient Greece)

  • Time is a measurement of motion/change.
  • Believed time is infinite and continuous.

🔸 Isaac Newton

  • Time is absolute and flows independently of anything else (“duration”).
  • Introduced Newton’s bucket argument to support absolute space and time.

🔸 Gottfried Leibniz

  • Time is relational—it only exists in relation to objects and events.
  • Argued against Newton’s idea of absolute space.

🔸 Albert Einstein

  • Proposed relativity of time: time and space are interconnected (spacetime).
  • Time moves slower for faster-moving objects (time dilation).
  • General Relativity explained Newton’s bucket via curved spacetime (geodesics).

🧮 Measuring Time

📆 Calendar & ⏰ Clock

  • Time measurement uses sexagesimal system (base 60), thanks to the Sumerians and Babylonians.
  • Example: 1 hour = 60 minutes, 1 minute = 60 seconds.

🕒 24-Hour Day

  • Ancient Egyptians divided day/night into 12 parts.
  • Greek astronomer Hipparchus proposed equal 12-hour day/night based on the equinox.
  • Fixed-length hours only became standard with mechanical clocks in the 14th century.

📐 Degrees, Minutes, Seconds

  • Hipparchus and Ptolemy divided circles and Earth’s coordinates into 360°, with minutes and seconds—basis for today’s geographic and time divisions.

⏳ Evolution of Timekeeping Devices

  • Sundials: Early division of daylight hours.
  • Water clocks (Clepsydra): Measured time using flow of water.
  • Candle clocks/Oil lamps: Marked events rather than precise time.
  • Hourglasses: Calibrated over time with mechanical clocks.
  • Pendulum clocks (1656, Huygens): Accurate to within 10 seconds/day.
  • Atomic clocks: Use cesium atoms, now the most accurate timekeepers.
    • The SI second is defined by cesium radiation cycles.