Time Travel is something that we humans have been contemplating for centuries. As our understanding of the physical and metaphysical world enhanced so did our theories to successfully achieve this impossible feat Each time great minds on the planet gets into the topic of time travel all eyes are fixated on them with the hope that they will reach a breakthrough, as for the majority of human history we thought space was simply an empty unending region that houses other planets, stars, and celestial bodies but the theory of Einstein changed it all, as the new theoretical concept, Wormhole was born.
Theory of Relativity
According to Albert Einstein, space as we knew was not simply a vacuum of nothingness but it was a 3-dimensional space that is wrapped and curved by the density of planets and stars. When the density of an object becomes extreme this space has no option but to collapse resulting in black holes, in which even the light cannot escape. As Einstein proved that nothing in the universe can travel faster than the speed of light, Einstein stated that as you start to travel closer to the speed of light, the time will start to slow down for you, however, time will remain the same for others, so in theory, you’d have traveled in time as when you return to your original point everything else would’ve aged slightly.
Representation of Einstein’s spacetime.
The String Theory
The theory is also known as the theory of everything, as we go into quantum physics all particles seem to be affected by three of four fundamental forces except gravity, and to ease the calculations, physicists think of particles as a point in the universe, this has allowed the rapid advancements in science but as soon as gravity is applied to these equations all the things fall apart. In this theory, points are replaced with strings that when vibrated results in different particles and properties. According to scientists shortly after the big bang, fluctuations in the space-time smaller than the atom created holes in it and through them flows the cosmic strings, and each end of these strings was pulled millions or even billions of light-years apart as the big bang expanded the universe and these could act as wormholes. Wormholes are hypothetical time-traveling tunnels in space.
A representation of the wormholes and cosmic strings.
Ancient examples of Time Travel
For as long as the concept of past, present, and future has been around, so has the concept of time travel. In Mahabharta, the story of King Raivata Kakudmi is mentioned where he travels to heaven to meet the creator Brahma, as upon his return he came to know that ages had passed since he left. Even in Japan, a similar tale exists, where a fisherman named Urashima-no-ko was fishing when suddenly he went to a deep-sea world for three days and upon his return, he found that 300 years had been passed and his family has died, his house is in ruins, and nobody remembers him. Even though modern theories did not exist during those times it is safe to say that there were some speculations or the very least tales of time travels.
List of Physicists who proposed Time Travel
As we can establish from these stories that this concept has existed for thousands of years. But it was not until the previous century that the theories began circulating.
- Albert Einstein: Einstein has contributed so much to the world that we can’t even begin to possibly think as we are still unable to comprehend his theories, as his theory of gravity was accepted 100 years after he proposed it. As mentioned earlier, he was correct about the structure of space and says time linearly goes along that space and it is the fourth aspect of our three-dimensional universe. Later on, he proposed something known as the Einstein Rosen Bridges. These were considered to be the first kind of wormholes and they were thought to be present at the center of black holes, it described black holes as a portal to infinite parallel universes. As we can observe the event horizon by seeing light bending around it, he proposed that if we were to cross that barrier we would come out of the other side of space-time via white holes where time runs in the opposite way and it is an upside-down mirror image of our universe. However, this skips over the concept of singularity, which is now theorized as to be at the center of a black hole, which compresses anything that enters the event horizon.
Albert Einstein in his office.
- Kip Thorne: An American theoretical physicist, though he did not suggest a theory for the possibility of time travel, he researched various aspects to understand if laws of physics permit it or not. He found universal mechanisms that prevent time travel to the past and in addition to that he also found that the paradoxes related to wormholes and time travel could not exist, either it is a paradox or it is a wormhole not together.
Kip Thorne giving a lecture on Black Holes.
- Frank Tipler: Born in 1947, Tipler is an American mathematical physicist and cosmologist. He provided a completely new theory for time travel and a concept known as the Tipler cylinder. In his theory, he suggested that if we were to build a hypothetical cylinder that has infinite length it can allow us to travel both backward and forwards in time. If this cylinder was to spin extremely fast along its long axis, a spaceship spiraling around the cylinder would be able to travel through time. However, creating such a thing is not possible as materials would be required that could withstand such extreme speeds and then there is the problem of infinitely long length.
A photograph of Frank Tipler.
- Ronald Lawrence Mallett: An American theoretical physicist, whose sole goal in life is to build a time machine. Unlike other physicists he is working with lasers, he observed that a circulated beam of light will actually cause space and time to get twisted, he stated that if gravity can bend time, as seen in the case of a black hole and light can affect gravity then in theory light can alter time as well. He claims that we all live linearly in a timeline that always moves forward and if this timeline is looped then time travel is possible but he says that it is only possible from and to the point when this hypothetical time machine is actually turned on. He is working on to build one.
A photograph of Ronald Mallet.
- Michio Kaku: American theoretical physicists and futurists proposed a new way to think of the string theory. He proposes a unique idea of time travel, he states that in quantum mechanics if a particle is observed at a particular time, the time split into two realities and we only exist in one that we observe and time travel may not be possible as we understand it but we might be able to reach to these splitting points in time, so you are altering somebody else’s universe.
Michio Kaku during a discussion.
- Stephan Hawking: One of the greatest minds of our generation theorized similar ideas of time travel like wormholes, however, he ultimately stated that these might not be possible due to various complications. However, later he started theorizing it again and reached the conclusion that it is possible, in fact, in the year 2009, he even threw a cocktail party for time travels, obviously, nobody showed up. According to his unique idea, he states that a spaceship should travel near a black hole, so close that effects of extreme gravity should start to affect spaceships’ time but not so close that it is sucked in the event horizon. So, even if the spaceship manages to encircle the black hole for one year, upon their return to Earth 10 years or even longer would’ve been passed, the astronauts would have only aged a year compared to the humans on Earth.
A young Stephen Hawking.
Though there have been many theories and concepts, time travel is still not possible. The idea sounds really appealing, but the complications and paradoxes that surround such a task are unthinkable, and even if we were to theoretically travel in time, how it would affect the timeline and individual is unknown. Ultimately, I’d say it is better to leave these theories to the paper and experts, and we must simply enjoy the time that we have to ourselves.
