The concept of time travel is as old as the evolution of human beings. The fact is that about 60% of world population fantasize about time travelling. This popularity has led to hundreds of sci fi movies and thousands of books based on time travel to be released all over the world. The concept of time travelling brings innumerable visions in our mind. Scientists from all over the world had tried their hands on this field and some of them have achieved immense theoretical knowledge about time travelling, which can be converted into a reality with our latest technology. We all had at least hoped once to go back to our past, so that we can change our future. If the theories of some of the most popular scientists are to be believed, then in the nearby future we will be able to travel in a time machine.

Time Travel

Time travel simply means travelling into future or the past from the present time. This concept enables a person to travel 1000's of years back into the past or forward into the future without altering the travelers's physical conditions (age). The gadget used in time travelling is known as a time machine.

Most Popular Time Travel Theories

 Albert Einstein

1. Theory Of Relativity

Albert Einstein, the world famous physicist, proposed the theory of relativity in 1915. We all know that we are living in a three-dimensional space. This space is a combination of length, height, and depth. According to Einstein, there are four dimensions in a space. This fourth dimension is known as the space-time continuum. We know that space and time can't exist without each other but in this fourth dimension they are indistinguishably linked with each other. Light always travel in a finite and constant speed. If two person are watching a football match from two different positions in a stadium, then the person who is more far away from the ground will perceive the events happening in the ground only after the person who is nearer to the ground. The event is occurring at the same time but the difference in perception between these two persons occur because of the time taken by light to travel through space. This dependency of time on space proves that, space-time continuum is actually a time machine.

2. Gravitational Time Dilation

a. The space-time continuum is the key to travel back in time. This is only possible when the structure of space-time continuum is altered. According to Einstein's theory of relativity a matter causes the space to curve. If we consider space-time as flat, then placing a planet on this flat structure will cause it to curve. This curve is actually gravity and smaller objects are attracted by this gravity, which causes a greater degree of curvature in space-time. In relation to time, this curvature causes the gravitational time dilation effect. If we check this possibilities with Earth then a time machine can be invented if we create a significant curvature in space-time to enable travel back in time.

b. Black Hole

Gravity not only pulls space but it also pulls time. The space-time attracts smaller objects which doesn't change time significantly but if it came into contact with a super massive black hole, then there will be a huge difference in time. If such an incident happens with Earth, then the people living in earth will experience time at half the Earth rate. It means that if a normal person lives 70 years on Earth, then after this incident it will be 140 years. This theory points out that time can be changed and if some alterations are made, then time travelling in the future is possible. The problem is that most scientists believe that a Black Hole can crush a planet.

c. Speed

The second aspect of gravitational time dilation is that when an object is moving faster, the time progresses slowly for that object in relation to a stationary object. If we observe the hands of a clock in a speeding train, we will see that it is moving more slowly than the hands of a stationary clock. This proves that speed is interconnected with time and this concept also throws light on how we can travel into future by remaining young forever.

d. Kerr Black Hole Or Rotating Black Hole

A kerr black hole is much safer than a black hole because it doesn't have a gravitational force at its center. Scientists believe that if we can enter through a Kerr black hole then the gravitational time dilation will take us into the future or into another universe.

Tom Kibble

a. Cosmic String

The theory of cosmic strings was first proposed by Tom Kibble in 1976. According to him, there are string like objects in space which were formed during the early universe. These strings are present through out the universe and their gravitational pull is quite strong. This gravitational pull of these strings can cause, objects passing near them to travel at incredible speeds and this time dilation can take these objects into future. It is theoretically proved that the gravity produced by pulling two cosmic strings can take a spaceship into the past. Cosmic strings can take you to future as well as the past.

According to some conspiracy theorists, the first incident of time travel and transportation experiment was carried out during the second World War and even today they are performed in top secret underground government laboratories. If they succeeded in creating a time machine, then the whole perception of mankind will change.

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