Few subjects fire up our imagination as much as time travel. H.G. Wells’ classic novel, The Time Machine, published in 1895, remains popular to this day. However, let us ask a serious scientific question: Is time travel possible?
Actually, no law of physics prohibits time travel. Indeed, numerous solutions to Einstein’s general relativity equations predict time travel is possible. Time dilation experiments (i.e. slowing down time), routinely performed with particle accelerators, lend credence that time can be scientifically manipulated.
The science community proposes three methods to travel in time. In brief, they are:
- Faster-than-light (FTL) time travel to the future – A clock traveling near the speed of light runs slower that a stationary clock. For example, it is an experimental fact that a clock on a jet plane flying over the airport runs slower than a clock at the airport.
- Using wormholes – A wormhole is a theoretical entity, in which space-time curvature connects two distant locations (or times). We infer wormholes from Einstein’s general relativity.
- Using black holes – Most scientists believe time travel requires enormous energy. Since a black hole already has the enormous energy we need, scientists postulate we could use it as a time machine.
None of the above time travel methods is within the grasp of today’s science. However, as we so often observe, today’s science fiction becomes tomorrow’s science fact.
In addition to the obstacles presented by the above time travel methods, some scientists have surfaced other obstacles, namely time travel paradoxes. Time travel paradoxes are thought experiments that illustrate that time travel may potentially violate causality (cause and effect). The most famous time travel paradox is the known as the “grandfather paradox.” It goes something like this: You travel back in time and meet your grandfather. When you meet him, you change events in such a way that he misses the opportunity to meet your grandmother. Thus, your grandfather never meets your grandmother, and they never marry. What happens to you? Theoretically, you will never be born.
Do time travel paradoxes make time travel impossible? Many scientists say they do not, and are able to propose numerous theories, themselves thought experiments, to resolve time travel paradoxes. Among them are Kip Thorne, an American theoretical physicist and Professor of Theoretical Physics at the California Institute of Technology until 2009, who argues that time paradoxes are imprecise thought experiments, which can be resolved by numerous consistent solutions.
We started this post with a deceptively simple question: Is time travel possible? The majority of the scientific community believes it is possible. In fact, some well-known theoretical physicists, like Michio Kaku, believe that time travel is an engineering problem. Even time travel paradoxes do not appear to present insurmountable obstacles.
In my book, Unraveling The Universe’s Mysteries, I present an original solution to Einstein’s equations of special relativity that delineates a relationship between existence and energy. The equation, which I term the “Existence Equation Conjecture,” appears to shed light on the mystery of time dilation, and to some extent on time travel. In fact, with the equation, I am able to predict the effects of time dilation on subatomic particles accelerated near the speed of light. The equation also provides a foundation to explain the universe’s accelerated expansion, which is the subject of a previous post, “Unraveling The Universe’s Accelerated Expansion,” http://bit.ly/RqWFYD.
It may be hard, if not impossible, to believe that time travel is possible. Yet, solutions to Einstein’s theory of general relativity, time dilation experiments, and the Existence Equation Conjecture suggest that time travel is possible. Welcome to the edge of science, where physics and metaphysics blur.