#too many fucking tags
One of the greatest questions of all time, has to be “whatIStime?”.
Is time defined by what we see on our mechanical clocks? Does time stop? Does time have a constant speed? Does time have a beginning and end? There are countless questions we can ask about time but what are the answers?
We are all familiar with time, our whole lives revolve around it. Yet, we don’t know everything there is to know about it. We can start by measuring time.
Hours, minutes and seconds were first adopted by the Babylonians, some say they even invented time. However, they could have never actually invented time but they made a system for time. The days were 12 hours and the nights 12 hours. The hours were broken down into 60 minutes and those that needed even more precise numbers, they broke down those 60 minutes into 60 equally big parts (60*60=3600 seconds).
To measure the time they used the human heart-beat, one second was the duration of time between the two heart-beats of a healthy human (in a relaxed state).
The first mechanical clocks were invented in the 1200s. They had a pendulum that swung back and forth. There are different types of clocks and therefor the clocks we use in our everyday lives are referred to as mechanical clocks. Biological clocks are quite important to us, the heart-beat is an example of a biological clock and even a woman’s menstrual cycle is a biological clock (probably not the kind of clock you’d want to watch).
Today we also use atomic clocks, they’re so precise that they will either speed up or slow down by one second in a million years. They’re based on specific type of radiation from the Cesium atom. The Second is now defined by this radiation and perhaps in some years we’ll invent even better clocks with yet another definition of time. However by current definition, a second is the duration 9,192,631,770 cycles of radiation in a transition, or energy level change, of the Cesium atom.
Picture above: A pendulum showing the acceleration (a) and velocity (v) vectors.
Is time a vector or scalar quantity?
Firstly, scalars are quantities that are fully described by a magnitude alone (Time and Mass) Vectors are quantities that are fully described by both a magnitude and a direction (Velocity and Force).
Time is said not to have any direction, only magnitude. Therefor it is a scalar quantity.
Another question that tends to puzzle humanity is about space and it’s length. Is space endless? Has it always existed? Is space just the distance between two objects or is it something more? If you took away ever last atom and object, would there still be space or would there be nothing? Even then you can ask, what IS nothing? Does ‘nothing’ exist?
One thing is for sure, we can measure length. There are many different measurements for length all over the world; Feet, yards, centimeters, etc. However the result is always the same, no matter how you measure. The distance that is there, is there and will not change no matter which measurement you decide to use. However, the international measurement tends to be in meters. The meter is defined by the movement of light.
A meteris the length of light moving in free space during a time interval of 1/299 792 458 of a second.
Why do we use light to define certain measurements? The light speed in a vacuum is the same no matter when or where we measure and it doesn’t even matter if the light source is moving relative to us.
It’s extremely hard to be 100% precise when talking about length and all length measurements are a little uncertain. Your height for example, let’s say your height is 162 cm. That means you’re between 161,5 cm and 162,5 cm. However, we’re getting better and better at being even more precise and inventing new measurements that will help us in the future.
Sources:
http://www.physicsclassroom.com/class/1dkin/u1l1b.cfm
Physics book: H.Aschehough @ Co. [W. Nygaard] 2007
