Is time travel possible?

By Lollie Rabin Year 10 Although time travel is sadly not what is portrayed in sci-fi movies, science says that it is technically possible to achieve, but there is much dispute about how fast you can travel. Albert Einstein’s theory of relativity states that time travel is possible but you can’t travel faster than the speed of light. Indeed, modern theories about wormholes, cosmic strings and the "Alcubierre drive" mean one can travel faster than the speed of light. This article will seek to explain these ideas and how they might make time travel possible.

What is Einstein’s theory of relativity?

Einstein published his paper on relativity in 1916 associating the force of gravity with the changing geometry of space-time. Essentially, it states that instead of gravity being an invisible force attracting objects to another, gravity isthe curving or warping of space. The bigger the objects, the more gravity warps the space around it. This is the same principle that all the planets orbiting around the sun in our solar system follow. This warping of gravity also affects the measurement of time. We tend to think of time moving at a constant rate, but as gravity can warp space, it can also dilate time. Einstein says that the faster you travel the slower you experience time. For example, when you are on an aeroplane, the clockwilltickata slower pace compared to when you are on the ground. Many experiments have been carried out to prove Einstein’s theory. For example, a satellite was equipped with sensitive gyroscopes (instruments which measure angular motion), to measure tiny twists and warps in space time made by the Earth as it moves and rotates through space. This proved that Einstein's theory had physical manifestations.

Why does modern day science say that you can travel faster than the speed of light? Idea #1: Cosmic Strings

Cosmic strings are the ‘texture of the universe’ . These strings are known as "topological defects" , meaning that they are not evolving or changing in any way: they are just there and cannot be removed. They were first discovered in the 1970s when technology became advanced enough for scientists to detect them.

When the universe was created, cosmic strings were formed 10-³⁵ seconds after the Big Bang went into the phase transition, a process similar to what happens with, say, water molecules when heated or cooled. However, instead of hydrogen and oxygen atoms changing shape, this change happened to the universe as a whole: where it cooled very quickly, spacetime "cracked" slightly into hairline fractures, not unlike the ones we see in blocks of ice. These cracks are cosmic strings. Even though the strings are invisible to most of our advanced technology they hold great amounts of energy. A key question is what happens when two cosmic strings pass each other: is the spacetime-warping so great that a person moving around them could take a shorter path, travelling faster than light, and thereby going back in time? If you circled the cosmic string would you be able to meet yourself before you everleft?

Idea #2: Wormholes

Wormholes are like tunnels in space, but they can also connect points that are vast distances apart via the warping of spacetime. We know that they exist due to Einstein’s Theory of Relativity as if you solve it in a certain way, the mathematical answer will give you a structure like one of a wormhole. Wormholes are formed through the gravitational attraction between objects from parallel universes competing against the resistance coming from the two different dimensions of our universe. When the attraction is greater than the resistance, the dimensions or borders between the universes deform, and the objects touch, creating the wormhole. Wormholes are only a theoretical theory as an example of them hasn’t been found in space yet. Creating a wormhole could be dangerous as to first create them, you need a black hole. As scientists do not know enough about black holes, it is impossible to judge what they will do and if they are stable enough to control. To use wormholes for time travel, scientists would have to find a way to move the mouth of one end of the wormhole in a specific manner, but there are risks associated with this. Wormholes could suddenly collapse or bring amounts of high radiation into the atmosphere, both problems that we don’t have the knowledge to solve.