Is time travelling is possible ?
This question is always a topic of discussion and argument over the ages. And being a Physics teacher this question is asked to me very often. Every time I answered this as Yes. Than student ask how ? I many a times say I don't know how but it is possible in the future. Today I am going to discuss on this topic :-
Let us start with a very basic question
What is time ?
Most people think of time as a constant, physicist Albert Einstein showed that time is an illusion; it is relative — it can vary for different observers depending on your speed through space. To Einstein, time is the "fourth dimension." Space is described as a three-dimensional arena, which provides a traveler with coordinates — such as length, width and height —showing location. Time provides another coordinate — direction — although conventionally, it only moves forward. (Conversely, a new theory asserts that time is "real.")
What time travelling is ?
According to Wikipedia " Time travel is the concept of movement between certain points in time, analogous to movement between different points in space by an object or a person, typically using a hypothetical device known as a time machine, in the form of a vehicle or of a portal connecting distant points in space-time, either to an earlier time or to a later time, without the need for the time-traveling body to experience the intervening period in the usual sense. "
So Time travel means travelling in time either in the backwards direction i.e. Past or in the forward direction i.e. future.
Travelling in future seems very amazing.
Special theory of relativity and general theory of relativity give wings to such dreams and discussion.
I think one day time travelling is definitely possible one of my co teacher who also teaches Physics says that time travelling will be possible that day when we are able to covert energy into matter.
This seems good but how ?
Some of the scientists also believe in the existence of wormholes and treat them as gateway of time travelling.
Few other theories of time travel are as discussed below
Infinite cylinder
Astronomer Frank Tipler proposed a mechanism (sometimes known as a Tipler Cylinder) where one would take matter that is 10 times the sun's mass, then roll it into very long but very dense cylinder.
After spinning this up a few billion revolutions per minute, a spaceship nearby — following a very precise spiral around this cylinder — could get itself on a "closed, time-like curve", according to the Anderson Institute. There are limitations with this method, however, including the fact that the cylinder needs to be infinitely long for this to work.
Black holes
Another possibility would be to move a ship rapidly around a black hole, or to artificially create that condition with a huge, rotating structure.
"Around and around they'd go, experiencing just half the time of everyone far away from the black hole. The ship and its crew would be traveling through time," physicist Stephen Hawking wrote in the Daily Mail in 2010.
"Imagine they circled the black hole for five of their years. Ten years would pass elsewhere. When they got home, everyone on Earth would have aged five years more than they had."
However, he added, the crew would need to travel around the speed of light for this to work. Physicist Amos Iron at the Technion-Israel Institute of Technology in Haifa, Israel pointed out another limitation if one used a machine: it might fall apart before being able to rotate that quickly.
Cosmic strings
Another theory for potential time travelers involves something called cosmic strings — narrow tubes of energy stretched across the entire length of the ever-expanding universe. These thin regions, left over from the early cosmos, are predicted to contain huge amounts of mass and therefore could warp the space-time around them.
Cosmic strings are either infinite or they’re in loops, with no ends, scientists say. The approach of two such strings parallel to each other would bend space-time so vigorously and in such a particular configuration that might make time travel possible, in theory.
You may also visit this link for one more discussion https://www.space.com/21675-time-travel.html
