Hang on a second, Mr.Aristotle!

Humans in general have this obsession to quantify everything around us and frame standards/units for defining it from time immemorial.

And in this post, we shall explore about our affiliation with the second- the unit of time.

What is Time?

Defining time per se is tricky, but without loss of generality we can define it as:

A measure to distinguish the past, the present and the future. And also to measure the durations of events and intervals between them.

How to measure time?

One could basically use anything that is periodic to define/meaure time. Even a pendulum for that matter.

One could say -’Bro, it would take 3500 pendulum seconds to get there.’

And that’s perfectly fine!

But it is not consistent and whose pendulum are you referring to?

Since It’s very hard to reproduce the very same conditions of the pendulum’s oscillation. A communication barrier arises.

Astronomical Time

Well, astronomical phenomenon seem to be consistent around the world, so why not define it in those terms. And ergo it was, for quite some time..

The second, was defined originally as the fraction 1/86 400 of the mean solar day. Great!

But there persists just this one problem:

The Rotation of the earth is not stable- it does not spin at a constant rate, it wobbles and does lots of other crazy stuff.

And this imparted irregularities in the measurement ( small, but with the passage of time blows up)

Atomic Time Keeping

We needed something that ticks consistently. And at this juncture, they turned to atoms. Let me first define the second and then take you through it:

The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom.

If you impart a specific amount of energy to an atom, it will jump from the present state (ground state) to an excited state i.e it will make a transition.

By defining a second as the number of these transitions  time can be so accurately measured that only a tiny portion of a second is lost every million years.

Pretty cool eh?


Food for thought:

Why is a second, a second long ? (or)

Why do 9192631770 periods constitute a second ?

Why choose Cesium?


Have a good day! ;)