The Big Bang

The Big Bang theory is the prevailing cosmological model of the observable universe from the earliest known periods through its subsequent large-scale evolution. In the September 2010 issue of Scientific American, George Musser, the Staff Editor of the magazine, has dealt with an interesting paradox of time. He says Einstein's general theory predicts demise of time and after that there is no tomorrow. According to science, time and space got created from an event called the Big Bang, some 13.7 billion years ago. Time has never ceased to exist since then. Time has been flowing in the forward direction for us ever since. Time also got entwined with space just like the two faces of a coin. Our universe has been expanding ever since the Big Bang and this expansion will continue for a long time to come.

The Big Crunch

Black Holes are the results of such big crunches, when a star or entire galaxy, collapses under the pressure of its own weight, resulting in a very tiny but very high-density object (for example, a spoonful of its mass will outweigh that of sun). This great gravitational pull does not allow even light to escape from it. This stage is called Singularity. So, from the outside, if you look at a Black Hole (be careful to stay from it or it will gobble you up!), it looks black due to the absence of light and hence the name. Relativity predicts that time will expire inside such a Black Hole. As our universe reaches its singularity one day, time will stop ticking. There are many contradictory theories on the fate of time and many scientists have proposed alternative models of how time will end or not end. Only time will tell! The idea of a past, present and future, comes from the flow of time. For us, time flows in only one direction from the past to the future. If you have hurt your beloved in the past, there is no way of going back in time to undo your fault. Our bodies and minds have been synchronized to the speed of time that we are used to on earth. Our sense of time is derived from the motion of our planet, moon, sun and stars, that influence us constantly. If our Earth was orbiting the star Sirius instead of the sun, our time sense would have been entirely different. Since Sirius is about 1.7 times more massive than our sun, it would have warped the space-time around itself so that we ended up in a different space-time framework altogether.

Einstein's space-time is generally imagined to be like a stretched rubber membrane that curves or warps when it comes under the effect of a heavy object like the Earth or the sun. It is like sleeping on a hammock. The centre of the hammock dips due to your body weight, warping the entire hammock. Does it mean that the fabric of space-time (like our hammock), can be ruptured or punctured? Can we make a hole in space or tear apart part of space? According to relativity, this is not possible as it will destroy the symmetry or homogeneity or smoothness that plays an important role in keeping the universe intact.

But scientific theories do allow for holes called ' Wormholes', in space-time. Wormholes are like shortcuts from one point in space-time to another. They act like tunnels that can connect for example, two different parts of space-time or two Black Holes. Well there is no proof of the existence of Wormholes in space yet, but they do exist in a lot of science fiction.

The End Of The World

In a 1985 movie, Back to the Future, a teenager boy is accidentally sent back to the year 1955, in a plutonium-powered time machine. His errand is to meet his yet-to-fall-in-love teenage parents and make certain that they marry, so he can return back to the future. The movie made for a fantastic experience and was a box office hit of the time. The protagonist in the movie used a time-machine based on Einstein's Relativity Principle to the fullest extent. Of course, he also violated the fundamental limit of the speed of light, which is fine for a movie and in anycase, without this, he wouldn't have gone back in time. While you can't get anywhere near the speed of light, going even faster is out of question. Relativity theories do not provide any hope for time-travel. The energy needed to make even a tiny sub-atomic particle of almost zero mass such as a proton, travel at the speed of light, is infinite, as the mass of the particle at the speed of light also becomes infinite. Imagine someone alive going at that speed and still being able to retain both body and mind. So, this possibility is ruled out.

But one of the profound implications of the time-travel idea is that we can treat time to be flowing both in forwards and backwards. Let's start with a very simple example of how we move along with time in our daily lives. Let's put down a simple list of activities for a typical day in our lives.