Travelling through time has proven to be an excellent and fertile source of ideas for many,many novels,video games and movies.Prince of Persia with his Sands; Doctor Who with the TARDIS;even Harry and Hermione with the Time-Turner.It can also be the explanation for any seemingly out-of -order thing.You know,The Final Destination series, for example.In all these scenarios, the characters possessed some objects which took them back and forth in time. But when we consider this in a more practical way,there are some serious hurdles for the assumption made above.Firstly,what is time?Is it real? As you think about this question, you picture the current moment before you.This moment absolutely exists,there is no denying that.But that’s all.All these moments exist,separately. Time is certainly a complex subject in physics.Its existence cannot be denied;yet is challenged by a few.Time is abstract.It cannot be actually felt. What we experience with each passing minute is the feeling that a “moment” has passed.
Time is a creation made to link up all these moments for study,much like complex numbers.Time is an illusion. According to Einstein, time is the fourth dimension.It is not an absolute concept. Rather it is a relative one.You cannot tell the time without a reference point. This essentially means that,like the axes of a graph, time stretches infinitely all over the universe.Provided with a sufficiently capable vehicle,one can travel across this line or “timeline” and land pretty much anywhere. That can be described as time-travel.However,Einstein’s quantum theory itself denies this.According to him,nothing can travel faster than light.We are left to assume that multiple universes exist.Universes where we live with different lives.You may be an industrialist in one,a beggar in another.But nonetheless,you.(Yeah,like the Jet Li,Jason Statham flick The One). Now there are some other interesting ideas about time travelling.Some believe that time passes slowly in space.So,technically,if I were to live in space for 50 years from now,then when I return,I would be a bit younger than you,even though we both have aged 50 years.To travel in time,you need a vehicle which goes faster than light.Now,ignoring Einstein,let us assume that such a machine does exist.Now what? How are you going to use it? The machine may survive those blazing speeds,but how would you possibly ride a car that goes 299 792 458 m/s without disintegrating? Time travelling therefore must be done with the traveller being stationary.Or, placing him away from all the “universes”.Wait until his desired place arrives,and place him down. Pretty confusing,huh?The fabric of time,according to some physicists,can be manipulated,but not with our present resources. And then,there is the good old Grandfather Paradox.Imagine if you travel back in time,and accidentally prevent your parents from getting together.That means no more you in the future.But wait,if you do not exist in the future,who travelled back in time then? Would you cease into nothingness right before everyone? Or would you be stuck into the past forever, living along with your parents.Then you would see your friends from the future as babies! God!
Conclusion:Our knowledge is painfully limited,and shamelessly flawed.