# Time flies when you’re having fun!

Before Mechanical Clocks

Before mechanical clocks were invented there were sundials, obelisks and water clocks which helped people tell the time of day it was. Sundials, obviously, told the time by the sun and the way it worked was with the shadows produced on the sundial. Sundials are the oldest known instruments for telling time. The surface of a sundial has markings for each hour of daylight. As the Sun moves across the sky, another part of the sundial casts a shadow on these markings. The position of the shadow shows what time it is. Water clocks, however, were used differently. Egyptian, Babylonian and others used ‘outflow’ clocks. Although in my opinion, water clocks would not be able to tell the exact time but would be able to show how much time had passed. They would also have to be refilled constantly in order for these to work.

Why 12/24 hours?

Egyptians had a theory and divided the time into 12 and 24 hours to determine the days.

10 hours of day

10 hours night

2 hours of half-light day (dawn)

2 hours of half-light night (dusk)

And these were arranged into 10 day groups (Decans – based on groups of stars)

This could possibly be the reason as to why we use 12 and 24 hour clocks.

Can animals tell time?

When this question was asked, I initially thought that it was possible but I couldn’t justify my reasons for this so I had to do some research into this. What I found was animals, such a birds, are able to understand the time of year as they fly south for the winter. Birds are aware of what time of year it is as they do this every year around the same time. This could just be because they start to feel the cold and are aware that this means the must fly south.

In my experience of animals and time, I have recently become more aware that maybe animals can tell time. I have a cat and he goes outside every night, around 10 o’clock and he is aware of this. Roughly at 10 o’clock, he will be waiting at the door ready to go outside for the night which indicates that he must have some sense of time. In the morning, when I get up around 7am, he is waiting at the door to come inside for the day. What I take from this is that he must be influenced by the sunlight but it could also be the length of time in which he is outside for.

Why do we need time?

Time is something I never seem to have enough of and I always say that there aren’t enough hours in my day to get anything done. Time is used every day by everyone. We need to know what time I must get up, what time I should leave to go to university in Dundee and how long it takes me to travel to university every day. If I don’t calculate this right, I wouldn’t make it for 9am lectures on time!

So I must calculate it like this if I have a 9am lecture:

• Wake up at 6.40am
• Leave the house at 7.45am
• Travel to Dundee (45mins – taking traffic into account)
• Arrive in Dundee at 8.30am (this ensure I have enough time to park my car and walk to the university)

I must work this out every day and this changes depending on what time my lectures start. So, I must use maths and time every day to ensure that I make it on time!

Is time linear?

In a recent workshop, the question was asked if we thought that time was linear. To me, this was a silly question because I had thought, of course time is linear that’s obvious! When looking into this it’s possible that we can actually time travel. This seems impossible but if we look at this with a different perspective, time travel is very possible.

Here is an example of time travel:

I travel to Switzerland at least 3 times a year. There is a time difference there of 1 hour. If I leave Scotland at 9am and it take 2 hours to travel there, I would arrive in Switzerland at 12pm. In Scotland it means that the time would only be 11am which means I have travelled forward in time!

Another example of this is:

If you were travelling direct from Australia to the UK it would take roughly 25 hours if travelling by aeroplane. This in effective is a whole day of travelling. If it is 10am in NZ on Wednesday 16th of November, in the UK it would be 9pm on Tuesday 15th of November. So, if you leave NZ at 10am on the 16th of November, you will arrive in the UK on Tuesday 15th of November. Therefore, you have traveled back in time!