After constantly rereading this article, I would have to say that I am still a bit confused on the notion of time and how it is defined. With that being said, it is clear that a second is defined as a fixed unit, with taking into account frequencies as well as electromagnetic radiation. As the articles states, most individual's agree that the caesium transition is used to define a second, but another ideology that was brought up in the article is that keeping specifications the same, all caesiun atoms have the same frequency. After redefining the second from the solar day, now "the second has been defined as the duration of exactly 9,192,631,770 periods of the radiation corresponding to a hyperfine transition of caesium-133 in the ground state". Although from my understanding this really is only stable/equal depending on the position of the atom, and from what I gather, if it is not always stable how can this be an accurate depiction? Along with that I learned that clocks measure these frequencies that involve caesium/atomic transitions. For example, there are a number of atomic clocks world wide which measure frequencies like the ones measuring atoms. Because these clocks have to be at a specific setup there is, although small, room for error. Which is why is it important that we look at hundreds of clocks around the world to get the most accurate measurement of time. By taking the weighted average of the different clocks is how they're able to get such a precise measurement.
Something I have always wondered was what did people use before the invention of the clock? During my research, something that I found interesting was that depending on where you were in the world, each standard of time was unique. Some examples were the decimal time system, which invented the ephemeris second. Shortly after came the invention of an atomic clock which ultimately stated that every year we lose approximately .6 of a second of time. Which personally I don't quite understand this ideology but I find it fascinating all of these different measurements before there was a universal definition of time.
-Lauryn
Hello Lauryn,
ReplyDeleteI think that there were numerous ways people measured time before the clock that we know and use today. In the earliest times there was the sundial which relied on the motion of the sun to determine the time. Although compared to the atomic clock it is highly inaccurate.
Hey Lauryn I also wondered what people used for time. Even further back I think of when people did not use the concept of time. It makes me wonder what a life is like where we just live and not have time controlling our days.
ReplyDeleteHi, Lauryn. Our current measurements of things like seconds, hours etc are all based off of the rotation of the Earth around the solar system. One complete rotation is one year. From there, a year is divided into months and so on. An interesting point is that the Romans made the calendar twelve months instead of ten; I think that, from this, you can see how the smaller measurements we derive from the rotation of the Earth is very subjective and could be easily changed. (Why is one second a 60th of a minute? And so on...). It is useful to have a standardized measurement of time across the globe, though, and measuring a second via atom transitions allows it to be constant in spite of the discrepancies in the frequencies at which different clock will run at. (some may be faster than others, so it's useful to compare the average time and determine outliers)
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