Time Travel - go Fast to go to Past

Time travel is a very abstract concept and very difficult to explain without complex mathematical equations and concepts, which is understood by a minuscule portion of the population. I will attempt to explain the concept of time travel in a simplistic manner. 

We will take the example of a fictitious murder for our understanding - just to add some spice to this drab topic.

Whodunnit

John was found, shot dead, in his room. You are the detective to whom this problem has been presented but despite using all the known methods, you are not able to crack the case. One Mr. Albert meets you outside the scene of the crime and suggests that you travel very fast to find out who murdered John.

You wonder how this escapist attitude can get you to solve the problem, but this is what he has to say:

John was murdered in a well-lit room. It is clear that there was a murderer who fired the bullet from inside the room, at point-blank range, to kill John. The light from the bulbs would have fallen on both of them and upon reflection from their bodies, would have gone out of the window.

If there was a person outside of the window - he would have seen the murder.  Alas, there was none! However, there was no stopping that light:  the image of the Murderer murdering John kept going on and on...

The forensic guys tell you that the Murder took place 2.3 Hours ago. Given the speed of light, that light carrying the image of moment of murder, would have reached Uranus (7th Plant of our Solar system).

Knowing the distance of Pluto from Earth you know that 5.5 Hours from the time of Murder the light carrying the image of the murder will flow past Pluto (the last planet in our Solar System).

You have 2.2 Hours to get to Pluto with your camera and when the light carrying the crime scene passes through Pluto - you can capture that on your Camera- nailing the culprit!

All good, but you would have to travel faster than light to reach to Pluto in 2.2 hours. If you did that, you traveled back in time.

Working on this analogy further, if you travel even faster or longer; you could see yourselves being born, see Dinosaurs and even the formation of the earth.

Mute Observer, when back in time

Yet, when you reach there, all you can do is to observe. The events have taken place and you can only see them, just like a movie. The observer cannot change anything - since you are not a party to the events. Its like being a ghost, who can see everything, but not talk to or interact with anyone else.

Time, like an eternal Film

In fact whatever we observe is like a film, the images that carry information about what is happening are moving from the objects to our eyes and we are seeing the frames. This light is also passing and going on indefinitely on and on.  You can imagine that there is a reel of film from here till eternity with information regarding your every moment spent so far and that film is traveling out at the speed of light.

• If you travel at the speed of light i.e., with the reel, you will see the same image: the time will become still for you

• A less than the speed of light will make you see things go in slow motion, and 

• If you travel faster than light then you could see things of the past.

Your clock thus becomes slow as you approach the speed of light. 


History in the Sky

We all travel in time i.e., go into history every time we see the stars.

Most stars that we see, may not exist today. It is their light that started long back - in some case millions of years ago, that reaches us today.

If we had good enough telescopes, we could see an earth being formed in another part of the universe, new creatures being formed in yet another part and possibly even more advanced societies spread elsewhere in the universe.

Reality Check

With our current knowledge and abilities - we cannot travel at the speed of light let alone faster. Going faster than light is fiction today, but it explains, how by going faster than light (at least theoretically) - you can go back into time. 

By the way, back at home a lot has happened while you traveled to Pluto and if you were to come back to earth, right after taking the picture, you would get to see your, great-grandson - perhaps 100 years after you left the earth. For you it was just a few hours to and from Pluto. We will talk about that in a later edition.


P.S.: To the purists, I acknowledge that certain things are not defined (such as going faster than the speed of light), and there are other ways to discuss this topic, but they are too mathematical or complicated for a layman to understand.