# Cosmos

[With phone in hand] Hello Mom!
[Mom] Son, you haven’t called me since two days. Are you too busy to talk to your parents?
[Me] No mom, I had a busy schedule for past few days. Do you know I’ve been nominated for travel?
[Mom] That’s great son. Now at least you will be able to find a life partner for yourself outside the country.
[Me] Let me complete my sentence mom. I’ve been nominated for time travel, not an ordinary travel to some other country.
[Mom] Since when companies have started sending people for time travel.
[Me] Mom, year by year applications for going to other countries are increasing. The number of applicants seeking a job opportunity in other countries has increased to such an extent that companies are thinking to send their employees for a time travel. Since very few people want to do that, I am the one who has been selected by our company.
[Mom] Son, I will talk to you later. You are dreaming.

The days are not far when the conversations like this will become a part of life and we will have people doing a time travel. Urban dictionary defines time travel as the moment when one does not remember what happened last night but actually time travel is a science fiction concept in which people are able to move backwards into the past or forward into the future.

Let’s discuss the travel into future. The great 20th century scientist Albert Einstein developed a theory called special relativity. The ideas of special relativity are very hard to imagine because they aren’t about what we experience in everyday life, but scientists have confirmed them. There’s a speed limit of 300,000 kilometers per second (or 186,000 miles per second) for anything that travels through space-time, and light always travels the speed limit through empty space. Special relativity also says that a surprising thing happens when you move through space-time, especially when your speed relative to other objects is close to the speed of light. Time goes slower for you than for the people you left behind. You won’t notice this effect until you return to those stationary people.

Say you were 15 years old when you left Earth in a spacecraft traveling at about 99.5% of the speed of light (which is much faster than we can achieve now), and celebrated only five birthdays during your space voyage. When you get home at the age of 20, you would find that all your classmates were 65 years old, retired, and enjoying with their grandchildren! Because time passed more slowly for you, you would have experienced only five years of life, while your classmates would have experienced a full 50 years.

Consider a man returning after a future time travel of 5 years meets his old friend who is now 50 years older though he should be only 20 years older and asking- “You had tough five years my friend?”

The kind of travel which excites us the most is the time travel into the past. Many of us wish to go to the period when Leonidas ruled Sparta and built an army of 300 Spartans to fight against Xerxes, many of us wish to go to the period to see Lord Krishna playing in Vrindavan. People become more excited when it comes to time travel in past because through this future can be shaped. There are various ways in which a time travel can be done.

One possible means of time traveling is via theoretic cosmic phenomena. Cosmic strings are the string like objects that some scientists believe were formed in the early universe. By pulling two cosmic strings close together or stretching one string close to a black hole, it might be possible to warp space-time enough to create what’s called a closed time-like curve. Using the gravity produced by the two cosmic strings (or the string and black hole), a spaceship theoretically could propel itself into the past. To do this, it would loop around the cosmic strings.

Another possible means is to look out for a wormhole. A wormhole is a theoretical passage through space-time that could create shortcuts for long journeys across the universe or the universes. Wormholes contain two mouths, with a throat connecting the two. The mouths would most likely be spheroidal. The throat might be a straight stretch, but it could also wind around, taking a longer path than a more conventional route might require. But the problem with wormholes is that they are highly unstable and very small in size. To make them stable we need an exotic matter which has the negative energy. Negative properties of exotic matter might push the sides of a wormhole outward, making it large enough and stable enough for a person or a spaceship to fit through it. Except exotic matter isn’t exactly easy to come by; it exists only in theory, we don’t know what it looks like, and we have yet to know where to find it. It’s even possible inserting anything that isn’t exotic matter but that would destabilize the wormhole completely. In other words: Entering a wormhole could immediately kill you. More recent research found that a wormhole containing “exotic” matter could stay open and unchanging for longer periods of time.

However, for the time travel in the past there are many paradoxes that come forward. One of it is ‘The Beautiful Girl Paradox’ that’s more of an imagination and the story of Cantona’s time travel goes like this-

Cantona hates a feminazi girl. Cantona hates her so much that his ambition is to murder that girl despite the fact that girl is already dead: she died in her sleep in 1945. Cantona is no quitter, however, so he decides to build a time machine with the help of a wormhole. To get into that small wormhole along with his spacecraft, he first stabilizes and pushes the sides of a wormhole outwards with the help of exotic matter. After that he travels back to the year 1935, a time before the girl’s death. Cantona buys a high-powered rifle, practices his marksmanship for many days, rents a room along the path the girl takes to work every day, and waits for optimal conditions. When the time is right, Cantona locks and barricades the door to avoid any intrusion, and otherwise prevents any factors that might keep him from hitting his target. Cantona is perfectly accurate when shooting any practical distance. As the girl walks by the room, he is only twenty yards away. It seems that Cantona can kill the girl. Every condition is optimal for a perfect shot that would kill her instantly. There is, however, the outstanding fact that girl dies in her bed in 1945. So, a girl gets two deaths. The same girl is murdered in 1935 and then dies of natural causes in 1945. Since we know the girl dies in her sleep in 1945, then it must be the case that Cantona does not kill girl in 1935. Now, it seems that Cantona can’t kill the girl.

This was the time travel story of Cantona. So, the observation is that a wormhole will remain a wormhole and no time travel will be possible until and unless the exotic matter with negative energy is discovered in order to stabilize and expand the wormhole.

We all travel in time and we all have stories to tell. During the last year, I’ve moved forward one year and so have you. Another way to say that is that we travel in time at the rate of 1 hour per hour. But the question is, can we travel in time faster or slower than “1 hour per hour”? Or can we actually travel backward in time, going back, say 2 hours per hour, or 10 or 100 years per hour?