The possibility of time travel has been long researched and thought of by some of the greatest innovators throughout history. However due to the underlying danger of conflict with the majority of the population, many people preferred to keep these views to themselves, to prevent the tarring of their reputation. As said by Sir Stephen Hawking, “Time travel was once considered scientific heresy.” (Hawking, 2010). However as times have changed and newer technologies proving the theories and ideologies of many scientists have been invented, people have found it possible to express their views on the theoretical study of time travel. With the collection of research studies by many influential scientists, which will be analysed in this essay, I plan on, theoretically, proving how one could travel through time. Although at this current time in the development of the human race we do not have the technology to make this a reality. This, although being a significant limitation, does not prohibit the minds of the world to hypothesise ideologies of how we can turn this into a reality. There are five possible methods of travelling through time ( however in this essay only four will be talked about due to the complexity and extremely low chance of the last theory’s accuracy) , in theory, these being : by speed, gravity, suspended animation and wormholes.
Method 1 – Speed
In theory, the simplest way to travel through time is by achieving extreme speeds. Taking into consideration Einstein’s theory of special relativity, when you travel at speeds near to the speed of light, time slows down for you relative to the rest of the world. This ideology has been tested. Physicists have taken twin atomic clocks and flown one in a jet and kept the other one stationary. The results showed that the clock which had been flown in the jet was tickling slower than the clock on the ground. In this case the effect would be minuscule. But If one was in a spacecraft which was traveling at 90% of the speed of light, one would experience the passing of time approximately 2.6 times slower than it would have been back on Earth. Therefore, the closer you get to the speed of light, the larger the extremity of the time-travel. The highest speeds achieved through any human technology are currently the speeds that the protons which are sped around the Large Hadron Collider achieve (99.9999991% of the speed of light). Using special relativity scientists can calculate one second for one such proton is equivalent to 27,777,778 seconds, or around 11 months, for humans on earth. (O’Connell, 2016)
There has in fact been a real life example of a person who has travelled through time, unaware of it at the time. ISS resident Sergei Krikalev held the record for the longest amount of time spent in space logging up 803 days, 9 hours, 39 minutes. The ISS travels at approximately 7.66 km/s when orbiting around Earth, therefore, due to the high speed and length of time which he spent in space, the cosmonaut actually arrived back on Earth 0.02 seconds in the future. This is due to time dilation. Time dilation is the difference between the time elapsed for two different observers. One who may be at a different velocity to the other causing the differentiation in time passed. (Atkinson, 2015)
Method 2 – Gravity
This method is also inspired by Einstein. In accordance with another of his theories, one of general relativity, the stronger the gravity one feels, the slower time moves for oneself. As you get closer to the centre of the Earth, due to the increase in the strength of the force of gravity, gravity is felt much more at the feet of the boy than the head. This effect has been measured. In the US National Institute of Standards and Technology (NIST) in 2010, a group of physicists placed two atomic clocks onto different shelves, leaving a gap of 33cm between the two (placed above one another), and measured the difference in their rate of ticking. The one which was lower down ticked slower because it felt a slightly stronger gravity. We can use the same ideology to travel to the future, we would only need something of great gravitational force, such as a black hole. The closer you get to the event horizon, the slower time moves – but it is an extreme risk to take, cross the boundary and you can never escape. Taking the assumption we had the technology to travel the extreme distances necessary to reach a black hole (the nearest being 3,000 light years away), the time dilation which would be experienced by just traveling to the black hole would be far greater than the effect of the time dilation processed through orbiting the black hole.. (Kennell, 2015)
Method 3 – Suspended Animation
Another way to travel to the future can be accomplished by stopping or slowing down your bodily processes, therefore slowing down your perception of time. Bacterial spores possess the ability to live for up to millions of years in this state of suspended animation, until the perfect conditions required for their survival are reached and they can start their metabolisms again. Some mammals, for example bears and squirrels also have the ability to slow down their metabolism during the process of hibernation, which dramatically reduces the requirement for food and oxygen from their cells. If humans were able to do the same this could be a genuine reality in the realms of time travel. Although completely stopping one’s metabolism is far beyond the capability of our current technology, some scientists have plans in the works of inducing a short-term hibernation-like state lasting at least for few hours in the works . This could be a breakthrough in the medical industry as it could be the necessary amount of time to keep someone alive, who many have gone through, for example, a cardiac arrest, until they can receive medical help. In 2005 a group of American scientists successfully experimented this technique of suspended animation on mice . This then led to experiments on larger animals such as pigs and sheep. However these experiments resulted in failure dampening the hopes of scientists in this field of study. Soon later, another method, which induces a hypothermic hibernation by replacing the blood with a cold saline solution, has worked on pigs and is currently undergoing human clinical trials in Pittsburgh. (Unknown, 2017)