Time travel – myth or a fact ??

Is time travel a myth or a fact??


To know the answer, head on past the break.

Situations :

1. There are two twin brothers. On their 30th birthday, one of the brothers goes on a space journey in a super fast rocket that travels at 99% of the speed of light. The space traveller stays on his journey for precisely one year, whereupon he returns to Earth on his 31st birthday. On Earth, however, seven years have elapsed, so his twin brother is 37 years old at the time of his arrival... Though the time is stretched by factor 7 at approx. 99% of the speed of light, which means that in the space traveler’s reference frame, one year is equivalent to seven years on earth. Yet, time appears to have passed normally to both brothers, i.e. both still need five minutes to shave each morning in their respective reference frame.
2. Your friend is sitting at the airport with a clock and you board a plane and take a 360 degree turn around the Earth in an airplane carrying an identical clock . When you arrive back at the same airport the your clock reads it has taken 47.5 hrs, but the clock in your friend’s hand reads 48 hrs.

Friends !! The truth in the situations described above may seem far fetched but lets discuss some “gibberish” , so that you all are in a situation to decide that the above quoted situations can be accepted or not.

To start with, “theory of relativity is an aesthetically appealing theory which may challenge your till date knowledge of physics”.


LIGHT – the ‘ultimate’ speed .

When we talk about velocity it has always a reference frame associated with it. Thus when we mention a speed, it is implied- reference frame is the material medium through which the wave travels. However , visible light requires no medium for transmission . It travels freely through vacuum of empty space with speed of 299,792,458 m/s …. , then what frame of reference you have in your mind ????
The answer is :
“ speed of light is has same value c in all directions and in all inertial frames - according to postulate of theory of relativity”.

The light will always measure same whether you are stationary on earth or you are moving in a spaceship with a velocity ‘½ c’. Thus, concept of frame of reference with respect to light is irrelevant.

Relativity of simultaneity

If two observers are in relative motion, they will not in general agree as to whether two events are simultaneous. If one observer finds them to be simultaneous, the other generally will not, and conversely. And its not that , that the two events are actually “simultaneous” but seems “not to be simultaneous” for the other. The events has actually occurred at the same time for one observer and it has actually occurred at different time for the other just because time became slower.

Watch the video to get a closer feel about the simultaneity.

Now comes the much awaited discussion on :

The relativity of time :

First watch this video explaining about cause of time dilation(time getting slower).

and now compare the photon containing box as below and analyse the cause of time dilation.

Consider 2 events :

Event 1. The turning on of the flash bulb B.

Event 2. The arrival of the light back at its source after reflection from

MIRROR on the ceiling .

Thus from the figure its clear that the time gets slower for the observer 2( in motion) by the factor :

This famous theory of relativity was given by Albert Einstein (1879- 1955) .Our daily life experiences are restricted to experience this theory as we do not have any direct experience with tangible objects moving faster than a tiny fraction of speed of light.

Hidden application of time dilation ;)

Pilots and astronauts can make best advantage of time dilation. If the pilots travel 20 hrs a day, they may actually had traveled 19 hrs(due to time dilation). Thus many airlines can put a maxima to their profit by minimizing the fuel cost by

having the minima of plane speed( greater speed -> more time dialtion -> more time slowed) and fuel consumption rate.