Would Scientists Really Be Able To Build A Time Machine?
For several decades, sci-fi movies and books on time travel have tickled our imagination into believing that maybe one day, some scientist or theorist will invent the magic of a time machine that will enable us to turn the clock upside down. We have asked ourselves zillion times, can it be done?In theory, time travel is possible, say prominent physicists and researchers. While travelling to the future is a theoretical possibility for now, latest research indicates that it is turning the clock back that is no longer a probability. Time is considered as the fourth dimension by physicists and it is compared to dimensions like length, height and weight. For example, when we go to our favourite coffee shop, we are travelling in all the spatial dimensions like length height and weight while traveling in time as well. Einstein's greatest ‘brainchild' is the theory of relativity, which gave new meaning to our understanding of space and time.
Time Travel And The Laws Of Physics
Simply put, time is relative and the laws of physics are the same all over the universe. Just like waiting for a bus on a sweltering hot summer day can seem to take forever, spending time enjoying a cool drink with friends may seem to pass too soon. In other words, different people or different events depend upon how the viewer sees them. A million years may seem like a blink of an eye for a space traveller in a high-speed spaceship or for someone falling into a black hole.
Space and time are tangled together in a sort of a four-dimensional fabric called space-time. Space-time is like a piece of spandex with four dimensions. When something that has mass - you and I, an object, a planet, or any star - sits in that piece of four-dimensional spandex, it causes it to create a dimple. That dimple is a manifestation of space-time bending to accommodate this mass.
When space-time (or the spandex), is bent, a curvature takes place in its path, which is referred to as gravity. For an even simpler explanation, physicists Mathematical calculations point to the theory that one can go backwards or forward in all the three dimensions, but in this four-dimensional space-time, we're only able to move forward in time.
Famous physicist Stephen Hawkins points out another interesting aspect. According to Hawkins, since we have not met any travellers from the future, it is quite evident that even if years from now, time travel is undertaken by people, they will only be able to go forward. A simple, but profound observation, to say the least.
Fourth Dimension Travel Guide
Physicists have chalked out a flight path for time travellers by putting forth some interesting ideas. The most popular route seems to be one that goes through a wormhole, which is a hypothetical tunnel present in areas of the cosmos connecting two sides of space-time. These two regions connected by the wormhole could either be bridges joining two different times in the same world, or two parallel universes. Travelling through the entrance from either side would deliver matter to the other side of the wormhole - a phenomenon often used in sci-fi movies and books.
Wormholes are the future, wormholes are the past. But we have to be very careful. The gasoline necessary to energise a time machine is far beyond anything that we can assemble with today's technology. When trying to punch a hole into the fabric of space-time would need the energy of a star, negative energy or some sort of exotic energy which amounts to less than nothing.
On the other hand, many people who study the subject doubt that the approach has any chance of working. But the basic idea , if we're very, very optimistic is that if you can fiddle with the wormhole openings, you can make it not only a shortcut from one point in space to another point in space, but a short cut from one moment to another moment in time.
For aspiring future time travellers, there is also another interesting theory: Cosmic strings are theorised as narrow tubes of energy, which stretch across the entire length of the universe and are leftovers from the early stages of the cosmos. These spaghetti-like strings of energy are presumed to contain enormous amounts of mass enabling them to warp the fabric of space-time. When one compares cosmic strings to spaghetti or spaghettio's we find that these tubes of energy exist either in loops or infinite strings without ends.
This is a project that a super civilisation might attempt. It's far beyond what we can do but We're a civilisation that's not even controlling the energy resources of our planet.
Building a wormhole
To further make wormholes simpler to understand, physicists compare the universe to skin of an apple, topologically speaking, if a worm tries to crawl to the diametric opposite point, it saves time by boring its way through the apple rather than taking the ‘round trip' from the outside. Additionally, in order to bring two points close together, one can bend a sheet of paper by folding it. This is similar to a wormhole, which has more than one point of entry and a tunnel-like ‘throat' in the middle. In the same way, cosmic wormholes can be used to bring two points in time together or to travel to another point in space-time by entering from one opening and exiting from the other.
Can we build one?
According to quantum physicists, they would be highly unstable just like a time machine. For one, it cannot be predicted when or where the wormhole might lead. So, as Star Trek fans might think that one can time one's exit from a wormhole to land in London in the year 2079, present theory says it is difficult.
But scientists say that a type three civilisation that is advanced enough and has learnt to harness the energies of its galaxy has perhaps mastered vortexes and possibly time travel as well. This is because they would be far advanced in their knowledge and technology to unravel the mysteries and use the energies present in the cosmos to their benefit. Does such a civilization exist? That is another story in physics. As far as we Earthlings are concerned, we are just on the threshold of being a type one civilisation.
If I could turn back time…
While travelling to the future is a theoretical possibility, going back in time does not seem to be a possible or plausible idea. For one thing, we are what we are because of who we are. Even if a slight change occurs in the event of someone visiting the past, the entire future of space-time would change. A slight interference in the events that followed up to the present times are the result of everything that took place in the past. And so, there is a chance that the past might be violated or damaged if a times traveller interferes. That is possibly the reason that scientists feel that though travelling to the past does seem like a theoretical possibility, it is also not good for ‘practical purposes'.
Time is like a meandering river flowing through space. As this ‘river' flows through the cosmos, it has whirlpools that might be openings into entering and travelling through it. The best vehicle would be a black hole. But with present theory, anything that goes through a black hole would be ripped at the very atomic stage. Unless an equation is invented to bring people out at the other end without being torn to shreds, we still await the much-needed time machine. But even then scientists feel there is no going back.