The tenth Doctor once said, time is just a big ball of wibbly-wobbly timey-wimey stuff. A professional in navigating it, the Doctor and his TARDIS have nailed travelling across the universe: but how can we indulge in our time travelling fantasties when we lack the blood of a Time Lord and the all-important time machine? To begin, it is important to consider the theories of Albert Einstein. Einstein defined time as an illusion. The theory of relativity dictates that time can slow down or speed up depending on how fast you move relative to something else. If one were to travel at the speed of light for instance, a person inside would age much slower than his twin – this is known as the twin paradox. This would be time travel. This notion of being able to navigate time is further apparent in the Einstein’s definition of time and space. Space is a three dimensional fabric which almost provides co-ordinates to the hypothetical traveller such as length and width. Time provides another co-ordinate; that of direction. The combination of the two creates a four dimensional fabric known as space-time. Even if one could travel at the speed of light, the equations still remain close to impossible. Some scientists have extended these equations which rule out impossibility. One of the ways in which these issues could possibly be resolved would be through wormholes. Creating wormholes between different points in space-time could enable time travel to occur. If this could occur, only very small particles would be able to pass through: that, and we as a species do not possess the technology to link points together just yet. In summary, Einstein’s theories are rather problematic in proving whether or not we could time travel. However, other scientists since Einstein’s time have offered up numerous theories on the matter.
How can we indulge in our time travelling fantasies when we lack the blood of a Time Lord
Firstly, the Infinite Cylinder theory. Created by Frank Tipler, this theory involves taking matter which is ten times the sun’s mass and rolling it into a long, dense cylinder. Then casually spin it for a few billion revolutions. If a nearby spaceship could get itself onto what is known as a “closed, time like curve” thereby presenting the ability to time travel. There are limitations to this theory however. The length of the cylinder would have to be infinite for travel to occur in addition to the existence of negative energy.
Another theory surrounds the concept of cosmic strings. These are narrow tubes of energy which are stretched across the entirety of the universe. These small regions are essentially the debris from the early cosmos and are thought to contain huge amounts of mass which could warp space-time. According to scientists, these strings are either infinite or in loops with no ends. If two parallel strings approach each other they have the potential to bend space-time in a specific, vigorous configuration which could make time travel possible. Again, this is a very specific circumstance and is difficult to initiate. There is also the notion of black holes. If one moved a ship rapidly around a black hole or create that condition with a huge rotating structure then time travel could occur. However, the crew would need to travel at the speed of light. There is also the issue of speed. The machine could fall apart if moving at very high speeds which obviously presents danger.
Thus far, different theories of how to travel time have been discussed. But consideration must be given to the vessel in which an individual would travel. Research on time machines involves bending space-time to the extent that the lines turn back on themselves which forms a loop known as a “closed time like curve”. Time travel needs an unusual type of matter that possesses bizarre properties which affects normal matter in strange ways. If this exotic matter exists, it is in too small a quantity to actually use within a time travelling device. It is possible without unusual matter but is rather complex. It involves a doughnut shaped hole being placed in a sphere of normal matter. Inside this vacuum, space-time is bent upon itself using focused gravitational fields which again creates a closed time like curve. To go back in time, the traveller races around the inside of the doughnut. Strong gravitational fields are however very difficult to handle.
But even if time travel was definitely possible, it would be lethal for humans. Using gravity would be deadly. If you stood on a neutron star, you would experience time dilation but the forces would rip you apart. Time travel is a very deadly business.
In all honesty, the Doctor has it easy. A flick of a switch and a whirling noise and a way he goes. That wibbly wobbly timey wimey stuff is much easier to navigate with a TARDIS.
