## How can we define time and why does it help us to know?

WHAT IS A MEASUREMENT OF TIME?

A measurement of time is the number of counts of time that passes between two events. For example, the time between the rising and setting of the Sun can be counted by starting a clock at sunrise and reading the number of counts it has made by the time the Sun sets.

WHAT ARE THE UNITS OF TIME?

Is important to have a system that allows everyone to understand how long one count is. This is important because a different person can then understand the measurement. This choice of the size of a count is called the unit of time. The standard unit is the second. This is about the amount of time it takes to say the word ‘elephant’.

For large amounts of time, like in the example of the setting Sun, the second is a very small unit, and will cause the measurements to have very large numbers. Instead we use hours. This is not a standard scientific unit, but it is easily converted and so is commonly used to make the counting easier. In the case of time, other units used are:

1 minute = 60 seconds
1 hour = 60 minutes = 3600 seconds
1 day = 24 hours = 1440 minutes = 86400 seconds

HOW DO WE MEASURE TIME?

We say that time moves forward and for forward time our number of counts go up. This raises important questions in physics about the understanding scientists have about the nature of time in the universe. These questions include why does time go forward and not backwards? Why can we remember the past and not the future? These questions are still being researched and the scientist addressing these questions hope to discover more about the way the universe works by answering these questions. VIEW ALL POSTS