How many physicists does it take to verify time travel? Just oneâwho knows how to project their present self to past and future selves. Kaboom! As funny as that may be, I just read a fascinating paper on nontrivial time travel. Science fiction has explored the concept for decades, with Marty McFly and the eccentric professor entertaining us in the 1985 classic, âBack to the Futureâ.
Did Einstein create inspiration for the time-travelling screenwriters with his general theory of relatively? General relativity predicts the existence of âClosed Time-like Curvesâ, or CTCs. CTCs, in theory, allow Marty McFlyâs signal to go back in time and interact with his former self. The filmmakers developed this theoretical concept as a physical projection between local (spacetime) region points A and B.
Time Travel Curves
In the movie, the eccentric professor urges caution in interacting with oneâs former self, for fear of invoking the grandfather paradox. What if Marty McFlyâs freedom of choice in the past ended up in his father, as a high school kid, being killed? Would Marty McFly cease to exist in this nontrivial event, known as the grandfather paradox?
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In 2020, IOPscience published a paper called âReversible dynamics with closed time-like curves and freedom of choiceâ. A highly complex read, but worth the effort. Quantum physics has expanded on Einsteinâs challenge to the fixed nature of the past and the future. He challenged the relationship between spacetime geometry and mass-energy, making provision for âClosed Time-like Curvesâ, or CTCs. A curve can signal into the past and the future, as a counterintuitive CTC solution.
Freedom of Choice Devoid of Conflict
The paper focuses on the isolation of CTCs existing between localized regions, once a fixed output is determined in a one-way signal between past and future regions. Their paper states the conditions for the proofs, where there is an absence of a logical paradox. For example, Marty McFly can talk to his fatherâs âyounger selfâ, but not invoke a logical paradox such as getting him killed.
The paper presents a finding that multiple agents/people can signal the future from the past without conflict between their locality in the present, freedom of choice, and logical consistency. Save for a logical paradox, the fear of affecting the causal construct, where past actions define the present and future, now faces a challenge from these time-travelling physicists.
Does Time Travel Have a Future?
Well, it certainly has a pastâas our science fiction community has shown through the success of Back to the Future. The filmmakers inspired a generation of thinkers to explore what is possible as much as what is probable. Like time travel, its relativistic future as a theory lies in further research.
Quantum physics as a set of theories was not a focus for research until substantial problems needed to be solved. By then, the first papers were nearly a century old. Time travel may seem like a dangerous subject outside of science fiction, but our universe is as dangerous as it is beautiful.
Many Paths Ahead
We must be brave in our choices, knowing we may never see the fruits of our labor. In the range of futures ahead for humanity, one such future could see a starship leaving a spaceport around âLunar Colonyâ. Its mission is to travel light years to the target star, which will see the crew experiencing time dilation.
On Earth and at the Lunar Colony, a normally aging humanity continues to do so. They saw off our intrepid explorers, and will never hear from them again. In normal spacetime, the passage of time slows down as the starshipâs engines push to or through the speed of light. Thousands of years can pass on a single mission in normal spacetime, as the starship arrives at its destination star. For the crew, this may only amount to weeks or months of space borne travel.
Wouldnât be nice to manipulate the relationship between spacetime and mass-energy on such a vessel? One may develop a technology to hop forward from fixed point to fixed point, instead of travelling through normal spacetime? From âBack to the Futureâ to new theories emerging about time travel itself, there is an important lesson unfolding. Our human community can inspire, innovate and exploreâwe know that. We can also do so in a manner that befits the grandest of reasons for why we are here.
About the Author
As I move onto my next authoring project, I will post less frequently on the real-world issues linked to my novel, From Terror to Valor: Echoes and Shadows. My next project, Hindsight Station, will initially be a progression science fiction, web-novel delivered via Patreon and eventually another web serial platform.
John is a versatile author known for his gripping fiction narratives in the thriller, action, and science fiction genres. With a background as a journalist since 2016, and expertise in cloud technologies as an engineer; John brings a unique blend of storytelling prowess and technical acumen to his work.
