I always wonder how my future will be or is there a way to go back in the past to change things, the way I want it to be. This leads me to do research about time travel. To start, let’s dig into what is time? In the ancient period, time measurements were done by making observations of cycles of the natural world, using patterns of changes from day to night and from season to season to build calendars. But what exactly are we measuring? Is time something that physically exists, or is it simply in our heads? At first, the solution appears obvious— in fact, time exists; it constantly unfolds all around us, and it’s hard to imagine the universe without it.
Our understanding of time started obtaining sophisticated forms due to Einstein. His theory of relativity tells us that time passes for everyone but not at the same rate for people in different situations, like those traveling close to the speed of light orbiting a supermassive black hole. Einstein resolved the malleability of time, by combining it with space to outline space time, which can bend but behaves in consistent, predictable ways. Einstein’s theory appeared to ensure that time is woven into the very fabric of the universe. Isn’t it confusing? What is it in real life? How scientists calculate? Which theory is correct? To know more about the theory of relativity, wait for the next article.
Did you ever wonder why we can move through space in any direction, but through time we can only move in one direction? No matter what we do, the past is always, stubbornly, behind us. This is called the arrow of time. When a drop of food coloring enters a glass of water, we instinctively know that the coloring will drift out from the drop, eventually dissolved in the glass. Imagine if the situation reverses. Here, we’d recognize time as unfolding backward. We live in a universe where the food coloring spreads out in the water, not a universe where it collects together.
In physics, this is described by the Second Law of Thermodynamics, which says that systems will gain disorder, or entropy, over time. Systems in our universe move from order to disorder, and it is the property of the universe that defines the direction of time’s arrow. So if time is such a fundamental property, it should be in our most fundamental equations describing the universe, right? Yes, it should, but there are some theories that do not take it into consideration, like the Wheeler-DeWitt equation, which doesn’t include time at all. Isn’t it amazing, we in day to day life don't observe such intricate details, but science is magic which teaches us all. I know that I might have left you with many questions, hence I want to start with some of the basics, to move ahead. Do you know what is the theory of relativity? Is it important to understand the concept? How does it help to understand time travel in deep? There are two types of theory of relativity, one is special and the other is the general theory of relativity.
The theory of Einstein's theory of special relativity explains how space and time are linked for objects that are moving at a consistent speed in a straight line. One of its most far-famed aspects concern objects moving at the speed of light. Simply put, as an object approaches the speed of light, its mass becomes infinite and it is unable to go any faster than light travels.This cosmic speed limit has been a subject matter of abundant discussion in physics, and even in science fiction, as people think about how to travel across vast distances.
The second is the General Theory of Relativity, which primarily applies to particles as they accelerate, particularly due to gravitation, and acts as a radical revision of Newton’s theory, predicting important new results for fast-moving and/or very massive bodies. The General Theory of Relativity correctly reproduces all validated predictions of Newton’s theory, but expands on our understanding of some of the key principles. Newtonian physics had previously hypothesized that gravity operated through empty space, but the theory lacked explanatory power as far as how the distance and mass of a given object could be transmitted through space. General relativity irons out this paradox, for it shows that objects continue to move in a straight line in space-time, but we observe the motion as acceleration because of the curved nature of space-time. For objects traveling close to the speed of light, the theory of relativity states that objects will move slower and shorten in length from the point of view of an observer on Earth. The speed of light in vacuum is constant and an absolute physical boundary for motion.
Did you ever feel, sometimes times pass by quickly like a speed of light while other times it goes very slowly like a sloth (animal). Remember the time, when you were studying, at that time, wasn’t it moving slowly? But when you were playing sports, didn’t you felt it moving fast? Would you like to know the science behind it? It’s all about relativity. General relativity describes the behavior of very large things, while quantum physics explains the very small. One of the biggest goals in theoretical physics over the last half-century has been reconciling the two into one fundamental “theory of everything'. There have been many attempts — none yet proved — and they treat time in different ways. Oddly enough, one contender called the Wheeler-DeWitt equation doesn’t include time at all.
Like the theories of everything, that equation is spectacular. But as a concept experiment, if it or a similarly time-starved equation turned out to be true, would that mean that time doesn’t exist, at the most fundamental level? Could just be some sort of illusion generated by the limitations of the way we perceive the universe? We don’t yet know, but maybe that’s the wrong way of thinking about it.Instead of asking if time exists as an elementary property, maybe it could exist as an emergent one. Emergent properties area unit things that don’t exist in individual items of a system however do exist for the system as an entire.
A film creates modification through time by employing a series of still pictures that seem to own a fluid, continuous change between them. Flipping through the photographs quick enough, our brains perceive the passage of time from the sequence of still images. No individual frame of the film changes or contains the passage of your time, but it’s a property that comes out of how the pieces are strung together. The movement is real, yet also an illusion.Could the physics of time somehow be the same/similar illusion?
Isn’t it fascinating that a human technology has approached 99% of the speed of light? Today I am going to tell you about , the theoretical ways in which we could time travel.
To start with, the first way we can travel through time is speed. Traveling at the speed of light is the easiest way to travel to the future. The theory of special relativity states that when you start approaching the speed of light, time slows down for you, compared to the other people in the world. An experiment is also conducted in the past to prove the theory of special relativity, by the physicists. It was done by comparing the time in people’s watch, traveling through an airplane and on the ground. After this experiment, it was proven that the people on the airplane is traveling at a higher speed in comparison to the others on the ground. For them, the time had slowed down. The highest speeds achieved through any human technology are probably the protons whizzing around the Large Hadron Collider at 99.9999991% of the speed of light. Using special relativity we can calculate one second for the proton is equivalent to 27,777,778 seconds, or about 11 months, for us.
The other way to travel through time is by using gravity. According to the theory of general relativity, if the stronger gravity acts on you, the slower the time would move. Taking the example of an airplane again, the people on the airplane would move faster than the people on the ground in terms of time because of the amount of gravity acting upon them. Another example is from the movie Interstellar, in which one hour on a planet near a black hole is equivalent to 7 years on another planet far from the black hole. This is because of the stronger gravity formed by the black hole.
When I researched, a question struck in my mind and made me wonder why the people travelling through airplane experience time fast in respect with gravity and slow with respect with speed. Finally, I got to know that it happens because speed is a greater factor than gravity. Hence, people on airplane experience the time slowly.
Have you watched the movie Avenger’s endgame? After watching it, I got very excited and thought how would it be to travel through time using quantum mechanics. It captivated my attention and motivated me to study deeper into it. What do you mean by quantum mechanics? Quantum mechanics is the learning of subatomic particles and also contains the concepts of quantization of energy, wave-particle duality, the uncertainty principle, and the correspondence principle.
Did you know that by studying quantum mechanics, you can create an ultra-precise clocks, un-crackable codes, super-powerful computers, biological compasses, etc. (To know more about it https://www.smithsonianmag.com/science-nature/five-practical-uses-spooky-quantum-mechanics-180953494/). The importance of learning this subatomic particles is to develop new and advanced technology (as mentioned above) and also to learn the structure of reality.
In quantum mechanics human technology has improved to a great extent. For example: CERN institute in Switzerland has claimed that they have approached the speed of light. There is a subatomic particle called the neutrino, which carries small particles which appear to travel faster than the speed of light. As Einstein’s theory states that objects exceeding the speed of light will need infinite acceleration and energy. It is still not possible for an object to have infinite acceleration and energy so it does not exceed the speed of light, but it may approach the speed of light.
The big question here is, can humans achieve the size of a subatomic particle? If we remove all the dead space inside our atoms, a single human could be able to fit in a single particle of lead, and the whole population would fit in the volume of a sugar cube. Although humans have advanced significantly in terms of technology but they have not yet been able to create a technology to turn humans into subatomic particle.