Before we take a look at the aspects of the Grandfather Paradox, let us first discuss how humans will be able to travel through time in the future. According to the extended version of Albert Einstein’s Theory of Relativity, a human will be able to go back to the past if he or she passes through a wormhole.
A wormhole is a speculative structure that links two separate points in spacetime, a mathematical model that combines the three dimensions of space and one dimension of time to four a four-dimensional structure. Now, time on Earth and spacetime are two different elements, as time on Earth can only be applied to humans since we are the only ones affected by the movement of the planet, while spacetime is the time determined by space or the universe. Through spacetime, we can assume that the universe follows a strict set of rules, which means that it is not absolute and unchanging. Because it is not absolute, spacetime appears as a continuous flow, and the flow allows us to either travel back or forward in time, since the past, present, and future are connected in spacetime.
By traveling through a wormhole, we are allowed to time travel, although the destination can sometimes be inaccurate. Consider the nearest galactic star in our solar system called Alpha Centauri, which is approximately 4.2 light-years away. A beam of light coming from Earth would take that much time to reach Alpha Centauri when traveling through ordinary space, but according to Einstein, you will be able to beat the light beam’s speed by taking a shortcut through a wormhole (see diagram below). If you enter a wormhole that suddenly pops up in 2012 near the planet Earth, you might end up at Alpha Centauri, although the year on Earth after your travel is 1912.
If the wormhole allowed traveling to a specific point in the Earth’s past, then there is a chance that you will meet your ancestors. That instance is where the Grandfather Paradox comes in.
Explaining the Grandfather Paradox
The grandfather paradox arises whenever a person meets his ancestors when he or she travels in the past. The paradox is supposed to ask the question, “What would happen to the time traveler after killing his or her grandfather in the past?” Despite its name, the grandfather paradox is not entirely limited to killing your grandfather, as it would still occur if you kill any member of your family that is supposed to be linked to your birth, like your mother, father, grandmother, or even your grandfather’s grandfather.
No knows when the grandfather paradox was actually conceptualized, but the term has already appeared in various science-fiction stories in 1929. In 1931, it was given a description in the American science-fiction magazine called Amazing Stories, stating that the grandfather paradox is an age-old argument about preventing the time traveler’s birth by killing his or her grandparents.
Scientists believe that the grandfather paradox would still occur even if the time traveler didn’t kill his ancestors, as it is speculated that it would be triggered if there was a major change in the past. If your reason for traveling is to change a particular event in your past, and you have succeeded in accomplishing your goal, then there is a possibility that the reason for your time travel will actually never exist, or you might even forget about the reason as to why you traveled to the past. As such, a major change in the past would severely affect the mental state of the time traveler while also affecting the events that will happen in the future. Moreover, if you succeed in killing your grandfather, you will cease to exist, and the future would be changed since the events that have been influenced by your grandfather’s presence in the present and future are altered.
How can the Grandfather Paradox be resolved?
There is currently no concrete resolution that has been brought up for the grandfather paradox, although there is a theory that the time traveler would travel to a different universe where his or her present and future wouldn’t be affected. For example, if you use a time machine to travel to the past and kill your grandfather, the grandfather that you are killing is actually from another universe, which means that you would never cease to exist, and your Earth’s present and future remained unchanged. In addition, the time traveler may also arrive in a universe where his or her ancestors don’t exist.
However, some scientists argue that the travel between different universe is not considered as “real time-travel” since the traveler doesn’t go back in time to his or her own universe. Regardless of all the speculations about traveling back in time, there is still no evidence that wormholes exist, which means that there is currently no way for us to perform time travel.