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Time: Where is it?

Time: Where is it?. Technology and Phenomenology. What is time? . Is time “real”? Why do we concern ourselves with time? How does time manifest itself? How can we measure it? What does time look like? Where do seconds, minutes, hours come from?

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Time: Where is it?

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  1. Time: Where is it? Technology and Phenomenology

  2. What is time? • Is time “real”? • Why do we concern ourselves with time? • How does time manifest itself? • How can we measure it? • What does time look like? • Where do seconds, minutes, hours come from? • What does the phenomenon of time say about us?

  3. Sundial ( or gnomon) • A “gnomon” is a linear instrument used to cast a shadow that tracks the sun’s relative position • The sundial uses a gnomon to assign the shadow to a specific time of day (determined by convention) • Sundials are the oldest general time measurement device known and used by all cultures.

  4. Sundial Continued • A real sundial takes into consideration the angles of shadow and attempts to conform to the suns path • To achieve standardized measurement, the gnomon must be tilted. From this we find the axis tilt and and can calculate the equinox and solstice days

  5. Clepsydra, akaWater Clock • The oldest know way of measuring a specific quantity of time • Used to make sure people had the same amount of speaking time in a debate • Used for measuring time in calculations of math for speed (speed = distance/time)

  6. Hourglass The hourglass is a common time measuring device that appears sometime after the 8th century AD, primarily in Europe.

  7. Time Measurement • One can measure time in terms of general universal time, as in “what time is it now?” • One can measure time in units, as in “how long does it take for a rock to fall from the table to the ground?” • There are generally two forms of early universal time measurement: The Sun and the Moon (+stars). • Solar time divided the day and the lunar cycle along with stars divided the night. • The environment is the source of our calendars.

  8. The Calendar The Babylonian Calendar (1500BC) was Lunar and Solar (12 months) The Lunar calendar and Solar calendar do not match up because the revolution of the Moon around the earth does not divide equally into the Earth’s movement around the Sun.

  9. Hijri Calendar and Roman Calendar Hijri Romulus and Numa Was only ten months until Numa added January and February (est. 750BC) Was lunar and did not conform to Solar year They left “the winter” out Is the basis for the modern European Calendar after many reforms • Lunar • Connected to Islam, begins with the Hijra (Ab. 622AD) • Dependent upon observation and does not conform to solar year • Does not conform to seasons

  10. The Julian and Gregorian Calendars Julian Gregorian Western and International calendar based on Julian Solar and based on the birth of Jesus. Where we get BC and AD (Was wrong about this date!) Conforms to seasons and is mathematical, thus easy to use Lunar Calendar used only for Christian Holidays like Easter. • Major Revision to Roman Calendar (~45BC) • Solar, 365 days, and leap day every 4 years • Lunar cycle still used for calculating certain dates and holidays • Tied to Roman Civil calendar and cultural events

  11. The Clock Began as mechanized versions of water clocks As machine craft improved over time the clock became an important navigation tool. First clocks as we know them today come from Europe around 1300. They used weights and springs instead of water. Mechanical clocks run out of power and “lose” time due to mechanical inaccuracies

  12. The clock tower and the minaret The clock tower in the Middle Ages served as a way to let everyone in town know when to come to church. It also helped the town know when to get up for work or when to stop and have lunch or go home. The clock tower used bells and chimes to announce the time. In the Middle East the call for prayer served the same function but was based on observing the sun.

  13. The timepiece (pocket or wristwatch) • WRISTWATCHES • Late 1800s • Not popular until 1920s • POCKET WATCHES • Were clocks on chains • Began use around 1600s

  14. Digital Clocks and Atomic Clocks Digital Atomic Clock Based on Atomic emissions and electromagnetic spectrum Extremely accurate measurements and used for sophisticated technology like satellites Would not be helpful if we did not have Einstein’s Theory of Relativity • Take advantage of electricity to manage units of measurement • The digit is opposed to the analog clock which shows that time sweeps and is not really a unit. Digital is built on a system of units that is not necessarily concerned with “universal” time.

  15. Time Zones and Satellites What time is it on the Moon?

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