By Colleen Murphy
A classic example of time travel that we are all familiar with is Back to the Future with the lovable, kooky scientist Doc Brown. Doc Brown is a comical caricature of what we would think a time travelling scientist would look like. This rambling man seems crazy and intelligent at the same time with crazy snow white hair and mismatched clothes under a hazmat suit. However, real time travel scientists look nothing like Doc Brown. The real time travel researcher I am referring to goes by the name Dr. Mark Wilde. Just to clarify, though, Dr. Wilde has not actually achieved time travel. However, he did publish a paper about time travel from the perspective of quantum physics.
Dr. Wilde is a physicist who researches quantum computing at Louisiana State University. He does not have a mismatched dressing style like Doc Brown or crazy white hair. He is just an average guy who rides his bike to school occasionally. In high school, he was good at math and science, so when college came his dad suggested he study to become an engineer. While Dr. Wilde was pursuing his masters, he took a greater interest in physics and he learned about quantum computing. Quantum computing as described by Dr. Wilde is “using the weird laws of quantum physics that deal with photons, electrons, and protons to make computations and communications faster.”
Now one would imagine that a physicist investigating time travel would probably have a really cool lab with all kinds of crazy machines and contraptions – nope. Dr. Wilde has no laboratory with crazy machines or any radioactive chemicals, for example plutonium, lying around to power a modified DeLorean. Instead it is a normal looking office space with a desk, a bookshelf and a large white board on the wall. The reason for this ordinary set-up is that most of Dr. Wilde’s research is theoretical, meaning there are no experiments in the traditional sense but rather it is all abstract. Trippy, right? When I first saw the white board there were numbers and letters drawn all over, and I could not help but think, “there is no way I am going to be able to follow this theoretical physics about time travel.” However this is where Dr. Wilde’s communication skills surprised me.
Dr. Wilde started off by introducing me to the grandfather paradox. “Let’s say you are a malicious time traveler, and you want to kill your grandfather,” Dr. Wilde joked while he began to draw on the whiteboard. He said that to go back in time, you would have to go to some future point through a wormhole when your grandfather was alive to kill him. But then Dr. Wilde poses the question: how would you be born in the first place if you kill your grandfather?
Another physicist named David Deutsch proposed an explanation to this paradox for all you future time travelers out there (excuse the pun). He looked at quantum mechanics where atoms and electrons can be in two places at the same time. In a particular interpretation, there are parallel universes where the electron is in one place in our universe then in a different place in another universe that are parallel to each other. Deutsch uses a mathematical model to explain these parallel universes. So remember that wormhole from before when you went to go kill your grandfather because you are malicious? Well that wormhole you went into put you into the parallel universe and you are really killing your parallel universe grandfather. Furthermore, in your universe you will continue to exist and in the parallel universe where you killed your grandfather the younger you will not exist but the older you will live on.
Now here is where Dr. Wilde and his colleague use their research to investigate other theories that can happen that could disprove Deutsch’s. Dr. Wilde and his colleague thought there was, in the words of Dr. Wilde, “something fishy” with Deutsch’s model. Dr. Wilde then broke into a mini lecture about Heisenberg’s uncertainty principle and provided me with the fun fact that this core physics principle was inspiration for Walter White’s alias in the TV show Breaking Bad. The Heisenberg uncertainty principle states that you cannot know how fast a particle is travelling as well as where the particle is in space. You can either know how fast the particle is moving or its position but not both. Dr. Wilde concluded by saying, “if time machines operated according to the Deutsch model then that would violate the Heisenberg uncertainty principle.”
Then Dr. Wilde says their next thought was, “what if there was a way to make time travelling stronger?” In the realistic world we can copy things like recorders copy words. We read and copy the book into our heads but this copying cannot occur in the quantum world, otherwise known as the no-cloning theorem. In the quantum world you cannot copy any part of the state in a quantum system. So in this model, time (the trajectory of some atom or model) is going up and you send in it back in time multiple times which evolves into a spiral pattern. This spiral pattern represents the time line turning back on itself which forms loops known as closed timelike curves. These closed timelike curves are caused by temporary wormholes. Dr. Wilde explained that “at specific instances there are multiple copies at given times, but since the wormhole disappears so does the multiple copies.” The desired effect would be after the wormholes disappear there would still be the multiple copies. In order to make these copies you need to find out what were the characteristics of the original copy. Read out gates from particles are used to gather this information. However, these read outs can cause disturbances that would in turn disrupt the copying. Despite the possible disturbances, if you could use the read out to characterize the original state of the copying then you can make as many copies as you want and travel as far back into time as you would like to as Dr. Wilde said, “to serve your malicious grandfather-killing purposes.”
Finally before my time had ended with Dr. Wilde, I asked him why he thought there were so many outlandish time travel plots in popular culture and he answered me by simply saying, “Time travel is more interesting if you can go back and change the past,” which I have to agree is true. I also asked Dr. Wilde if he thought there were any “accurate” fictional time travel stories. He told about one science-fiction short story that caught his interest: “The Men Who Murdered Mohammed” by Alfred Bester. In the story, a scientist tries to travel back in time to erase the existence of his cheating wife. However, the vengeful scientist encounters the problem of wormholes taking him into parallel universes similar to Deutsch’s model. The funniest part of the story for Dr. Wilde is when the scientist has to seek help about the complexities of time travel from the man who is having the affair with his wife.
I think the most surprising thing I took away from shadowing a scientist was how easy it was for Dr. Wilde to communicate his theoretical time travel research. Before the shadowing process I was worried that I had picked a scientist too far outside my realm of knowledge and that I would be left with no understanding to write about any part of the research. However, Dr. Wilde had done exactly what a good science communicator would do. He thought about what he was going to say before the interview, when explaining his research he never had to “dumb it down” but explained any parts that seemed unclear. I strongly recommend watching the video for yourself to really grasp the visuals of theoretical time travel. When I asked Dr. Wilde what had prompted him to research something about time travel, he said it started out as a fun project between him and colleagues. They knew that time travel was not ruled out by the laws of physics however speculative it might be. The relation between time travel and quantum computing according to Dr. Wilde is, “what are the consequences for information processing with time travel?” So even if we don’t have the research for practical real life implication in time travel it is still neat to talk to a scientist like Dr. Mark Wilde who has come pretty close-and without any plutonium or DeLorean necessary.
Editorial Note – Edited by Dr. Paige Jarreau