Buzz
In the BBC show 'Dr. Who,' the Tardis — a time-traveling machine — is cleverly disguised as a blue police box. As a Time Lord, The Doctor exists beyond the confines of time, with no clear distinction between past, present, and future.
Photo by Peter Macdiarmid/Getty ImagesMain Points
- If time travel were not restricted, it could cause a complete collapse of the natural order we rely on.
- The capacity to visit both past and future would radically alter our comprehension of time itself.
- Stephen Hawking's 'chronology protection hypothesis' proposes that there may be natural barriers stopping unrestricted time travel.
Time travel has been explored in science fiction for over a century, starting with H.G. Wells' 'The Time Machine' in 1895 and extending into modern films like 'Déjà Vu' starring Denzel Washington. However, physicists have also long investigated the concept of time and whether time travel is feasible, beginning with Albert Einstein's theory of relativity. Einstein's work revealed that time slows down as objects approach light speed, and that gravity can also slow time. This means that, in a limited sense, we are all already time travelers, experiencing tiny time distortions (of mere nanoseconds) when we, for instance, board an airplane. Today, physicists are seeking practical ways to generate time warps that would enable noticeable travel into the past or future.
In his book 'How to Build a Time Machine,' physicist Paul Davies states, 'The theory of relativity suggests that a limited form of time travel is definitely possible, and unrestricted time travel — to any period, past or future — could potentially be achievable.' This remarkable claim raises a key question: If time travel were to become a reality, how would it alter our current understanding of the world?
First, it's crucial to acknowledge that constructing a time machine would likely require vast resources, and the complexity of such a device would mean that only a select few would be able to travel through time. Yet, even with a small group of 'time-traveling astronauts,' the impact on our world could be profound. The possibilities seem almost limitless.
Let’s assume for a moment that we can create a full loop in time travel — that is, time travelers could journey into the past and then return to the future (or vice versa). While scientists generally see traveling to the future as less complicated than traveling to the past, our daily lives wouldn’t drastically change if time travelers could only move backward or forward without being able to return. However, if we were able to complete this loop, the potential effects would be truly astounding.
Exploring the Possibilities and Paradoxes of Time Travel
Picture a time-traveling astronaut sent 100 years into the future. This individual could witness technological breakthroughs beyond our imagination, much like how people at the dawn of the 20th century couldn’t fathom the technologies we take for granted in 2010, such as iPods or laptops. The astronaut could also gain insights into future medical innovations, like new treatments, medications, and surgical methods. If the traveler could bring this knowledge back to the present, society could experience a dramatic leap in its technological and scientific development.
The futuristic time traveler could also bring back knowledge of what lay ahead for the world. He or she could warn of natural disasters, geopolitical conflicts, epidemics and other events of worldwide importance. This knowledge could potentially change the very way we operate. For example, what if a time traveler journeyed into the future and literally saw the effects that automobiles would eventually have on our planet? What if the time traveler witnessed an environment so polluted and damaged that it's unrecognizable? How might that change our willingness to use alternative forms of transportation?
Imagine that time travel became less restricted and more available to a larger population. Perhaps travel into the future would be exploited for personal gain. A futuristic time traveler could draw on knowledge of the stock market to guide his or her investment decisions, effectively using the granddaddy of all insider information to amass a fortune. Militaries might rely on time travel to gain valuable knowledge about the enemy's positioning and resources in future battles. Terrorists could use time travel to scout out the scenes of future attacks, allowing them to carefully plan with precise knowledge of future conditions.
The potential effects seem equally limitless in terms of the less likely possibility of time travel into the past. History books would no longer be based solely on exhaustive research and interpretation of ancient materials. Time travelers could resolve historical debates and verify how things did or didn't happen in the past. Imagine how different our understanding of the world might be if we could say definitively, for example, whether Moses actually parted the Red Sea or whether Lee Harvey Oswald acted alone in killing John F. Kennedy. A journey into the past could prove or disprove religious beliefs or result in face-to-face encounters with people such as Jesus, Buddha, Napoleon or Cleopatra -- or even the time traveler's former self. Perhaps time travelers could even bring back from the past things that had been lost, such as extinct species or dead and long-forgotten languages.
But here it's very important to raise the issue of self-consistent narratives and paradoxes. The concept of self-consistent narratives tells us that anything a time traveler would alter or affect in the past would have to remain consistent with the future from which he or she journeyed. Changing the past would effectively change the future, creating a causal loop. But such causal loops would only pose inherent problems if changes to the past resulted in a future different from the one the time traveler came from.
But perhaps the question of how time travel would affect life as we know it goes deeper than even a discussion of potential paradoxes and causal loops. Perhaps a discussion of specific effects of consequences on life as we know it makes little sense when faced with something that could change everything about the way in which we perceive our world.
Physicist Paul Davies provides an example of a consistent causal loop in his book 'How to Build a Time Machine.' A math professor uses a time machine to travel into the future, where he uncovers a new theorem. He then returns to his original time and shares the idea for the theorem with one of his talented students. This student later publishes the theorem, and it turns out that the professor had read the very same work during his trip to the future. This scenario illustrates a consistent causal loop.
In contrast, with the grandfather paradox, a time traveler journeys into the past and kills his grandfather. But if the grandfather dies before the time traveler is born, how can the traveler exist? And if the traveler doesn’t exist, how can they go back in time to kill their grandfather?
Time Travel: A Total Chaos
As physicist Paul Davies explains, unrestricted time travel — which means the ability to loop back and forth between past and future — would lead to complete chaos. He says, 'Time travel presents a view of the world that is akin to a madhouse where the rational order of things no longer functions. In such a scenario, it’s difficult to envision how everyday life could persist.'
In a reality where the relationship between the past, present, and future is completely flipped, we would surpass the things that define our current existence. Our understanding of time would be shattered, potentially causing such a profound disruption to our worldview that we would lose interest in things we currently prioritize: work, finances, social plans, shopping — you name it. These concerns would seem irrelevant in this new and chaotic world because we'd be consumed by the challenge of making sense of a reality without a fixed timeline — we'd lose track of the sequence of events.
Therefore, discussions about settling historical debates, saving endangered species, or gaining advancements in technology, finance, or military strategy might become trivial, as these objectives could very well be sidelined in the unpredictable world that would emerge following the rise of unrestricted time travel.
As Davies explains, none of the chaos mentioned would result from one-way travel. A one-way journey to the future or even the past (assuming we adhere to self-consistent timelines) wouldn't lead to such a radical disruption of the world as we know it. However, completing that loop of time travel could, quite frankly, be disastrous.
Davies highlights that science fiction typically emphasizes the intriguing aspects of time travel. Yet, he asserts, 'It's not a novelty or a curiosity; it’s something that challenges the very rational foundation of how we live and operate. It’s nearly impossible to imagine that anything could ever be the same again.' In his perspective, unrestricted time travel could alter life in such a profound way that we wouldn't recognize it. With chronology losing its meaning, we wouldn't be able to distinguish whether something occurred before or after, whether one event was the cause or the result, and we'd lose the ability to predict the outcomes of our actions. Essentially, it would be like we had all gone mad.
These alarming potential consequences of time travel have led some scientists to question whether there is a natural principle that might prevent unrestricted time travel, like Stephen Hawking’s 'chronology protection hypothesis.' This kind of 'theory of everything' could potentially offer a scientific reason for why we could never destabilize the universe with unlimited time travel. While such a theory has yet to be discovered, Davies' perspective on the terrifying repercussions of time travel certainly makes one hope that such a theory is found soon — even if it means we may never learn for certain who was responsible for JFK's assassination.
