Leap seconds??

One of the things that I love the most about science is that we are constantly seeking to improve on the status quo. "If it ain't broke, don't fix it" assumes that the object in question is already perfect, and we all know that that isn't necessarily the case! Once upon a time, before the 1950's, we based the passage of time on the rotation of our planet. This was about 1/86,400th of the average solar day. If this seems totally arbitrary to you, you'd be correct! It seemed like a good idea at the time - a day should always take the same amount of time to pass, right? It turns out we were wrong; due to the Moon's gravitational pull, the Earth's rotation is slowing down at a rate of about 1.7 milliseconds per century.

In the post 1950's era, time is now based on the atomic clock, which defines a second as "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 caesium 133 atom". We don't need to get into the nitty gritty details about what this means, but know that this is a way more precise means of measuring time. However, because we were on the old method for so long, we've been behind the true time for many years now. To correct this, we occasionally add a "leap second" to the year to make up for this difference.

Figure 1: FOCS1, a swiss atomic clock

So in the end, who the hell cares? Assuming our species exists in the universe for many millennia, we would eventually lag behind significantly in time in comparison to the "true" time, so we might as well fix it now. Hyper accurate time is also important in having accurate electronics and other devices that base their calculations and actions on time. Fixing these time differences can be a lot trickier than what I've described here, so for more information check out this wonderful post by The Conversation.

So on June 30th of this year, rejoice! You'll get a brand new, shiny second to enjoy. What will YOU do with your second?