Questions tagged [time]

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9 votes
1 answer

Where did the popular idea of spacetime come from?

[This question is about popular conceptions and therefore goes into strange directions, don't get too shocked] The notion of spacetime can be traced back to roughly the 18th century where some people ...
Slereah's user avatar
  • 865
19 votes
1 answer

How did Ptolemy know that days were unequal lengths?

Apparently Ptolemy was aware of the fact that the duration of time from noon to noon varied by many seconds throughout the course of a year. In modern times this fluctuation in length of day leads to ...
Jagerber48's user avatar
1 vote
0 answers

When did the concepts colloquially referred to as "the past" and "the future" first appear?

I'm writing a paper on the history and the origin of Time and I'm finding it impossible to locate any meaningful material on how the concepts colloquially referred to as "the past" and "...
Tivity's user avatar
  • 111
1 vote
1 answer

Is there another calendar with the equivalent of gregorians weeks?

In the gregorian calendar, we split the time in years, months, weeks and days. A week is the total of seven days. I was looking at the persan calendar, being one of the most precise known calendar. ...
Itération 122442's user avatar
6 votes
1 answer

What did Galileo's "pulsilogon" look like?

Reading how Galileo measured time in the experiment with inclined plane, it says on Wikipedia, that: Galileo accurately measured these short periods of time by creating a pulsilogon. This was a ...
pisoir's user avatar
  • 163
1 vote
1 answer

At what time people relized the changes in times between countries? [duplicate]

At what time people understood or realized that there are changes in times between countries and continental, and when it's a day in one place it's a night in another place? Allegedly, It makes sense ...
Ubiquitous Student's user avatar
4 votes
1 answer

When were clocks used for the first time in science?

Time has been mechanized already by sundials. These nails and chains that are banged in and put around time have been increasingly refined to accumulate in the advent of the atomic clock. So-called ...
Deschele Schilder's user avatar
5 votes
1 answer

Why historically the hour was divided into 60 minutes and when it had started? [duplicate]

Why and when was the hour divided into exactly 60 minutes (and not for example 70 or 80)?
Ubiquitous Student's user avatar
1 vote
1 answer

When and how was it discovered that the sun was in different positions depending upon longitude?

It seems to me that the ancient Greeks knew that geographic location affected the apparent position of the sun in sky but given the lack of rapid travel or communications or reliable clocks, how was ...
releseabe's user avatar
  • 1,123
3 votes
1 answer

Did Weizsäcker's change his mind about time being a fundamental object?

I have some questions about von Weizsäcker's views in physics, which I find them generally interesting. One of them is that he thought that time was fundamental (he even thought that logic, which is ...
vengaq's user avatar
  • 297
1 vote
1 answer

What is the historical basis for the length of a sidereal year?

It is understandable that the length of a solar year can be found out using the time of solstices. But how did they find the length of a year with respect to the stars?
Arnab Chowdhury's user avatar
0 votes
0 answers

How were sundials first divided up into hour-long segments?

Even with present-day knowledge of celestial mechanics, if you asked me to go outside and set up a sundial without the aid of any other timekeeping devices, I would have a very hard time. The time ...
Display Name's user avatar
1 vote
0 answers

Why are there 24 hours in a day?

The question could be answered in a number of ways: Historically (e.g. Egyptians did for <...> reasons) Mathematically (It is a highly composite number) I'm looking for a mathematical answer. I'...
Abhigyan's user avatar
  • 119
3 votes
0 answers

Did the French ever use the decimal time in science?

Have you ever seen a scientific paper/document that uses the decimal time introduced during the French Revolution? I'm not looking for any paper that uses decimal time like in astronomy, but instead ...
Mauricio's user avatar
  • 3,324
4 votes
2 answers

Why were extremely accurate sundials necessary in India?

I'm thinking specifically of the Jantar Mantar sundial in Jaipur, India, the Samrat Yantra. It is apparently accurate to within 2 seconds, and was built around 1740. What would such an accurate ...
Michael Stachowsky's user avatar
0 votes
2 answers

Were people in the ancient or medieval times aware of how exactly a solar year is equal to a lunar year?

Was it common knowledge around 600 AD or perhaps 30 BCE that 200 solar years for example were equal to 209 lunar years? In which period of history precisely can we say that such a thing was confirmed?
Malux's user avatar
  • 1
5 votes
2 answers

Did English ever use a third (1/60 of a second) for measuring time?

An hour has been divided in sixty minutes since medieval times. During the 16th and 17th century, clocks measuring a second subdivision emerged. Today we still use the sexagesimal system for ...
gerrit's user avatar
  • 213
4 votes
3 answers

How did people count seconds before clocks were invented?

How did people count seconds? How did people count minutes? How come that every second of a clock takes exactly as much time as needed to be 86400 to fulfill 24 hours and 31536000 to fulfill a year? ...
Foxcat385's user avatar
  • 149
3 votes
2 answers

Was there ever a proposal for Metric time

The time keeping system I've been taught and use has the following (cumbersome) units: Months, Days of the month, hours of the day, minutes of the hour, and seconds of the minute... above and below ...
Neoheurist's user avatar
3 votes
6 answers

Have there been accurate alternative clocks/ways to tell time?

As I understand it, pretty much everybody uses the "Babylonian/sexagesimal" time format: 12/24 hours in a day, 60 minutes in an hour and 60 seconds in a minute. Have there been alternative systems to ...
Gerhard's user avatar
  • 133
3 votes
3 answers

Why does the start of the calendar year not correspond to a natural event?

Why is Jan. 1, the start of a new year, several days after the Winter Solstice, instead of coinciding with a solstice or equinox or other natural annual event? Note: The question does not ask why ...
WBT's user avatar
  • 231
5 votes
2 answers

Why did Greek Olympic games take place every fourth year?

I was wondering why Greeks chose to have Olympic games every four years. Now, since we usually every fourth year is a leap one, it makes sense; but the reform of the calendar which stated this is due ...
mau's user avatar
  • 1,277
10 votes
3 answers

What is the historical basis for the length of a year?

It is currently accepted that a year is equal to the time it takes for the earth to revolve around the sun. However around Roman times, Ptolemy's geocentric model was the widely accepted view of ...
cspirou's user avatar
  • 251
7 votes
2 answers

When was the issue of time zones at different longitudes first described?

What are the earliest recorded acknowledgements of the concept that motivates time zones - that the sun and other celestial objects appear in different parts of the sky to people at different ...
Isaac Moses's user avatar
5 votes
1 answer

How did the notion of "time" come in the world of physics?

I was trying to figure out how people came to know about time then I realized that people started keeping track of time to know about sunset and sunrise. But I can't figure out how did time came into ...
Soham's user avatar
  • 175
19 votes
3 answers

When and on what basis was it decided that an hour have 60 minutes and a minute have 60 seconds?

There were always some or he other means of measuring(estimating) the time. But I always wonder that when and how the present time system (1 Hr. = 60 Min., 1 Min. = 60 Sec.) evolved ?
Amit Tyagi's user avatar
  • 1,478