A River Named "Time"

Have you heard of a river named time? You must have, you’ve even see it flow. If you still didn't get it look at your watch. See it flowing? Yes that’s what I am talking about, “Time". Some rightly call it the fourth dimension. We can travel through three dimensions till now, but travelling in the fourth dimension has been the dream of many. We will get to the traveling part later, let's first define “Time”.

So Time is the system of those sequential relations that any event has to any other, as past, present, or future; indefinite and continuous duration regarded as that in which events succeed one another.

Didn't quite understand that? Well if we simplify it Time is a measure or scale used to describe the sequence of events occurring within a given period. The past, present and future represents time.

Just like any other dimension time is also a dimension which can be traversed, theoretically at least. Time you know is measured in seconds, minutes, hours, day, months, years and many more units.

Did you know even a particular type of distance is measured in time? The distance between stars, planets, galaxies and many other heavenly bodies up there high in the sky are measured in light years.

Now what is a light year? It is the total distance travelled by light in a year. 1 light year = 9.461 trillion kilometres, and the speed of light is approximately 3.00×108 m/s.  Just to give you an example the distance between Earth and Mars is about 225 million km on an average. Actually as the planets revolve around our Sun, the distance vary time to time, sometimes they come very close and sometime far away. So we had a record close encounter with Mars in 2003 when it was only 56 million km away from Earth, yet they can be farthest apart when they are both at their farthest from the sun, on opposite sides of the star which would be around 401 million km approximately. Coming back to our example, light from Mars could take 12.5 minutes to reach earth on the average distance and when it does reach Earth we see a tiny spec in the night sky of what Mars was 12.5 minutes ago.  If you get a telescope strong enough to find the Nasa’s Mars rover “Curiosity” you would actually see the activity its was doing 12.5 minutes ago not its present actions. So that my friend is looking into the past. Yes we do look into the past, it’s in front of our eyes every time, we are just too busy to notice it sometimes and ignore it. Next time when you look up in the sky and you see the stars, planets and even galaxies remember one thing you are actually traveling to the past. If you see a supernova (exploding star) with a telescope 100 light years away consider it that what you are seeing has already happened 100 years ago and you are just watching a history. May be after the supernova in the current time there is a blackhole or may be there is nothing at all in that place but as the light from that supernova took 100 years to reach your eyes you had a glimpse of the past.

Someday when we can travel with speed of light or rather faster than that we will have our time machine. The closest star to our Earth other than the Sun is Alpha Centauri which is 4.4 light year away or 40 trillion km approximately. Lets forget the kilometer scale and consider only the light years for our ease of understanding. Alpha Centauri being 4.4 light years away simple means light from it would take 4.4 years to reach Earth. In other words what we see of Alpha Centauri today is actually what it was 4.4 years back. Now if we have a spacecraft ready which can travel faster than the light and we reach Alpha Centauri in an about a year. So now from Alpha centauri when you look back into Earth with a highly powerful telescope guess what do you see? Of course you see the Earth as it was 4.4 years back. Let’s say we started with our journey on 2016 August and you reach Alpha Centauri on 2017 August and you look back to Earth and guess what, you can see Earth as it was in 2013 approx. Yes that is the science of time travelling at the very basic. Why do we see year 2013 because by the time we reach there, faster than the speed of light, the light which travelled from Earth to Alpha Centauri in year 2013 took 4.4 years to reach. By the time we reached Alpha Centauri as our spacecraft took us a year to get there so it’s already 2017 on Earth. We arrive on Alpha Centauri in the same time the light from Earth on year 2013 arrives. Thus we see Earth as in 2013 standing there in Alpha Centauri.

The secret to our time travel remains encrypted within the “Light” itself. As you can understand by now we see something when light falls on it. So in order to look at your past shed some light on it first. With today’s technology it’s mere impossible to do that, but still the concept is enough for now to amaze us and then one day travelling through time can be as easy as catching a train.