Consider the Avengers: Endgame- Quantum Physics
If only I had more time…
Quantum Physics has always been and will always be an interest of mine. The person who helped influence this is my grandfather on my father’s side. My grandfather had two degrees. One being a master’s degree in Chemistry and another being a bachelor’s degree in Quantum Physics. On the weekends, my parents would drop me off over his house and he would take me with him to his laboratory job where he and his lab partners would conduct many different experiments. Throughout the course of time, I grew apart from him. My grandfather passed away in 2011 and for the longest time, I felt guilty. I wish I could have had more time with him but by the time I realized this, it was too late. It made me realize how I took time for granted.
So, one day, I saw Avengers: Infinity War in theaters. In the ending of the movie, half of the universe is destroyed by Thanos. The key premise of the movie is that the only thing that can reverse the deaths of half the universe are the things that caused those deaths in the first place, the high potent infinity stones. The problem is this, Thanos destroyed the infinity stones in present day so the stones are only available in the past. Trying to get these stones back will require a complex journey back in time to numerous locations by the remaining avengers.
Some of the problems that can come with this are traveling back in time can cause logical unpredictability, like the Grandfather Paradox. The Grandfather Paradox is explained like this; if you went back in time to kill your grandfather when he was young, then you could have never been born but if you weren’t born, then how did you go back and kill him? Scientists have several theories about these time loops (closed time like curves.)
Some theories state that such loops are just physically impractical and that traveling back in time can never happen. Albert Einstein introduced the theory of spinning black holes that can twist both space and time, which is why one side of the black hole is brighter than the other in the first picture ever taken. In the movie, the characters make fun of many other time-travel movies such as Back to the Future and all the Terminator series where changing your own past and future is possible.
Instead, Avengers: Endgame goes with the different reality idea, where any changes back in time cause a whole new alternate universe to be created, a so-called splitting or subdivide off multiple timelines. In physics, this is referred to as Many Worlds Theory. To keep away from the problem, the Avengers plan to take the stones from past timelines, use them in the present day but return them to the same moment once they have finished with them.
This brings us to Quantum Mechanics. Quantum mechanics is a theory of matter that is based on the concept of the possession of wave properties by elementary particles, that affords a mathematical interpretation of the structure and interactions of matter on the basis of these properties, and that incorporates within it quantum theory and the uncertainty principle. It is common for atomic particles to be as indistinct as waves of probability. For example, in an MRI (Magnetic Resonance Imaging) scanner, imaging relies on a quantum mechanical phenomenon called spin. The spin gives the atomic nuclei of human body their own magnetic fields which is then observed through imaging.
A British physicist by the name of David Deutsch, who is mentioned in the movie, combined the idea of never knowing exactly where a particle is and what direction it is moving. One can only know that there is a certain chance of it being in a certain place.
Deutsch combined this idea with the Many Worlds theory or Many World Interpretation which is a theory in quantum physics that explains the universe containing some non-deterministic events, but the theory itself intends to be fully deterministic. To simplify this, every time a “random” event takes place, the universe splits between the various options available. Each separate version of the universe contains a particular outcome of that event. Instead of one continuous timeline, the universe under the many world’s interpretation looks more and more like an array of branches splitting of a tree limb.
Deutsch showed that the grandfather paradox can evaporate if you express everything probabilistically. Like the particles, the individual going back in time only has an assured probability of killing their grandfather, breaking the calamity loop. This has only ever been simulated successfully. If finding this hard to understand, do not become upset because even scientists are struggling to make sense of the connotation of the quantum theory.
Throughout the movie, certain terminology is used for several of the time travel theory scenes. Some of the terminology is used on topic while some are used off topic such as Eigenvalues. This terminology is used off topic. In the scene where Tony Stark and Bruce Banner talk of eigenvalues, it is most likely for the movie math’s talk effect as eigenvalues is a basic concept in linear algebra. If a verdict was needed, it is just a case of the math mumbles meaning this math was used to add fabrication to the scene. The Planck scale is used to describe microscopic things. The Planck length, time and mass are base units used in physics. A Planck length is 1.616 x 10^-35m which is very small. It happens to be the distance of light that travels in one unit of Planck time which also happens to be a very small amount of time. Although the movie is about quantum mechanics-based time travel, mentioning the Planck scale is not very far off topic. The verdict for this is that Planck has a point. The last terminology is called Inverted Möbius strip. In the movie, it talks about inverting a Möbius strip. A normal Möbius strip is a surface with only one side. An individual could create one easily by taking a strip of paper, twisting it up once, and then attaching it together. Although a Möbius strip has a range of interesting mathematical assets, its technical relevance to time travel is insubstantial, beyond some high-level attempts to explain the grandfather paradox. The verdict for this is that the theory was twisted just a little and this is because it added to the effects of the movie.
In conclusion, from a scientific perspective, seeing that there is a movie with such a considerable plot foundation in time travel and the movie does not pull away from many time travel scenes which just adds the extra effect to the movie. Although some of the mathematical terminology is there for obvious effect, the plot for the movie is reasonable. The attempt to comply to current high-level thinking about time travel is exactly to the point. Time travel is a fascinating scientific concept that maybe is furthest from implementation from scientists and so its climactic role in a movie about superheroes who can fly, go infinitesimal, annihilate universes and change reality is perhaps exceptionally fitting. I’m happy that I was influenced at a young age. I’ve learned over the course of the years that time is not something to play with. I’ve learned to cherish the ones I love before it’s too late because time will continuously move forward.
