Paranormal
Haven't you always been fascinated by time travel? You've probably wished you could go back in time and save that relationship that went wrong, or ace that test which could have led your career in another direction or perhaps travel to the future, to see if there really are those flying cars and super-advanced technology in people's homes.
People all over the world have been coming up with their own designs for such a time travel machine. The only thing required now, would be a good knowledge of physics, space-time, and plenty of processing power at your disposal, and you should be able to do it yourself.
This article will not go into the issue of whether time travel itself is possible or not, or into the several time-travel paradoxes that are possible, but simply into a few new time travel machine designs.
Kip Thorne Machine
Kip Thorne suggested that as a logical consequence of Einstein's theories, wormholes most certainly would exist. A wormhole is basically a tear in space-time that serves as a shortcut to another point in space time. However, wormholes are yet to be detected. Thorne had suggested that a wormhole's entrances could be positioned in space-time as (and when) desired, making the destination something more relevant to the concept of space time. This suggestion meant that you could enter a wormhole, and come out at another point in time, just a few feet from where you entered.
For reasons, the details of which I will not delve into, this design allows you travel back and forth in time, but not before the machine was created.
Here's how the design works: Take four large metallic plates, several kilometers in diameter, and place them parallel to each other. The distance between the plates, however, should be extremely small, so that the Casimir Effect can take place and populate the area between the plates with negative energy.(The Casimir effect is a small attractive force which acts between two close parallel uncharged conducting plates, It is due to quantum vacuum fluctuations of the electromagnetic field.) This allows for identical portions of space time to be created.
Next, the plates are to be divided into two pairs, and a wormhole would form and connect the pairs. One of the pairs of plates would then have to be placed in a spaceship and accelerated to the about 99% the speed of light. Since time will almost stop for the set of plates in the spaceship, you can wait as long as you would like (perhaps years or centuries) and step between the pair of plates with the wormhole. You will be then transported into the spaceship, across time and space, to reach the other pair of plates.
This all sounds great and easy (to the uninformed). But the problem here, is that the plates must be a distance apart less than the distance of an atom. The wormhole formed will be just as small, so getting in and out would be difficult for a human. Perhaps a nanobot could be sent up through the plates, which would travel back in time and establish contact with a specified person at a specified time. Other problems could include the danger of the radiation emitted by the wormhole, or the gravitational effects of the wormhole killing you.
Gott Time Machines
When the Big Bang first occured, it is believed that several topological defects in phase transitions of matter led to the creation of several different entities. Of these entities, the one that concerns us here are cosmic strings, which are basically long 'strings' consisting of vast amounts of compressed matter. Cosmic strings are leftovers from the initial transition phase after the formation of the universe, wherein symmetry is broken, and persists thereafter. Cosmic strings are very long, and could even stretch across the entire universe. They are also very thin, a billionth of the radius of a Hydrogen atom. Strangely, just a few kilometers of a cosmic string would weigh as much as the Earth.
Richard Gott discovered that if two of these cosmic strings could be placed parallel to each other and made to move in opposite directions, they could warp space time to allow time travel into the past. Gott reworked his theory to use only one cosmic string for time travel, and is now known as Gott Loop Time Machine. The first step is obviously to find a cosmic string somewhere in the universe. Next, you would have to take your spaceship to where the string is located, and using the gravity of the spaceship, shape the string into a large rectangle, about 54,000 light years wide, and 0.01 light years wide. As you do this, the gravitational forces of the longer sides of the rectangle would cause the sides to collapse in, nearly at the speed of light. As this happens, wait until the sides of the rectangle are 10 feet away from each other, and use your ship to start circling the string. Once you complete one circle around the collapsing rectangle, you will have travelled back in time.
But, in order for you to travel back by just one year, the string would have to weigh about half as much as the Milky Way, and your ship probably quarter that size.
There is also another time machine proposed by Gott, referred to as Gott Shell Time Machine, which allows for travel only into the future. Here, you must create a Gott Shell, which is basically a large concentration of mass. The mass is concentrated to such a high density that the gravitational field produced slows down the clock for anyone inside the shell. So, all you need to do is to collect lots of matter, weighing about as much as Jupiter, and assemble it into a sphere, making sure you leave out enough space at the center. Once it is created, and you are inside, compress the shell you're in, and the more you compress the shell, the faster you'll be transported. Once this is done, you only need wait, because time will be flying outside the shell, and decompress yourself at a later point in time. Once outside, you should be in the future.
I would think that the Gott Shell and Gott Loop machines would be required if either one of them are used for time travel.
The Van Stokum Cylinder
This is an idea based upon a discovery by physicist W. J. Van Stokum. He realized that an immense cylinder spinning at light speed would drag space-time along with it, as though it were a treacle dragging molasses. This was an idea that was developed upon, and it was then theorized that if a spaceship were orbitting the spinning cylinder, or a person were walking along the surface of the cylinder, she would be exceeding the speed of light, and thus time would flow backwards. Simply turning around and orbitting the cylinder in the direction opposite the spin would take the person into the future.
All this would require then, would be the collection of a large amount of matter, like planets, stars, and asteroids, and then for them to be shaped into a long cylinder. Next, an extremely high electromagnetic field would be used to start the spinning of the cylinder. A spaceship would, of course, be orbitting it, and with each circle of the cylinder, the spaceship would have travelled a certain amount of time into the past or future.
The only catch here is that the cylinder would have to be infinitely long.
Kerr Ring Time Machine
In 1917, Schwarzschild had discovered that stars could collapse into infinitesimally small points in space of infinite density, what we now refer to as black holes. Forty years later, Roy Kerr discovered that some stars do not collapse totally, but collapse into rotating rings, known as Kerr Rings. These rings have such intense gravitational forces, that they can distort space-time, and since they can permit large objects to enter on one side and exit on the other in one piece, Kerr-type black holes can serve as portals to the past or the future, and it would be merely a matter of finding one.
Or, one could create their own ring by gathering matter equivalent to Jupiter's mass, and compress it to a ring of about 5 feet in diameter. While compressing, it would also have to be spinning, and once its velocity nears the speed of light, a black hole will form through the center. You can then step through the hole and will be taken to another point in space and time. However, once you step through, you can never return. It's a one-way ring.
Goedel Universe
This is possibly the least interesting of all the possibilities here. It simply makes use of a hypothetical Universe, which is static, non-expanding, rotating, and infinite and actually permits time travel. In such a universe, there was a rotating fluid, such that if you walk in the direction of rotation, you would eventually end up where you started, but backwards in time.
I don't believe I need to comment on the possibility of the existence of such a Universe.
Other Time Machines
Other time machines include the Ori-Soen time machine, which involves a time machine with flat space-time and a region of altered geometry, and Aharonov's Quantum Time Machine which suggests that quantum mechanics do indeed admit jumps into the distant past or future. However, only quantum particles may do so, which almost eliminates the possibility of humans using this feature.
Star Trek fans would delight at the possibilit of Warp Drives, which permit faster-than-light travel. It does so by distorting space-time around the travelling ship, and in effect creates a region of space that moves with respect to the rest of space-time. Such a device requires the use of exotic matter, wormhole time machines, and a new family of time machines. Such a space/time ship would surf along the waves created. Or, it could travel in something called a Warp Bubble, which could be formed by contracting space in front of the ship and expanding it behind the ship and would thus enable the ship to actually travel faster than the speed of light. However, to accomplish this, more energy than the Universe could provide would have to be supplied to the ship.
