Thanks to particle accelerators, like the Large Hadron Collider (LCH) 175 meters (574 ft) beneath the Franco-Swiss border near Geneva, Switzerland, physicist have been able to routinely demonstrate forward time travel (i.e., time dilation) using subatomic particles. In a sense, you can think of the Large Hadron Collider as a time machine. It is capable of sending subatomic particles to the future. Unfortunately, we do not have a similar machine that can send subatomic particles to the past. However, Dr. Ronald Mallett is attempting to change that.

Dr. Ronald Mallett is an American theoretical physicist and the author of Time Traveler: A Scientist’s Personal Mission to Make Time Travel a Reality (2007). Dr. Mallett is a full professor at the University of Connecticut, where he has taught physics since 1975.

Dr. Mallett is attempting to twist spacetime using a ring laser (i.e., a laser that rotates in a circle) by passing it through a through a photonic crystal (i.e., a crystal that only allows photons of a specific wavelength to pass through it). The concept behind spacetime twisting by light (STL) is that by twisting space via the laser, closed timelike curves will result (i.e., time will also be twisted). In this way, Dr. Mallett hopes to observe a violation of causality when a neutron is passed through the twisted spacetime. Dr. Mallett also believes he will be able to send communication by sending subatomic particles that have spin up and spin down. Note, the spin of a subatomic particle is part of the particle’s quantum description. As a simple example, we can consider spin up equal to 1 and spin down equal to 0. Using this technique, Dr. Mallett can send a binary code, similar to the binary codes used in computing.

Few scientists openly discuss their work on time machines. They fear ridicule. In this regard, Dr. Mallett is a pioneer. When Dr. Mallett was ten years old, his father died at age thirty-three from a heart attack. Dr. Mallett has shared that his initial drive to invent a time machine was to go back in time and visit with his father. Unfortunately, the science of time travel only allows a person to go back in time to the point when the time machine is first turned on. Dr. Mallett acknowledges this, but continues his quest.

Dr. Mallett’s concept of twisting space is close to the concept of creating a wormhole, as discussed in my last post. Dr. Mallett is using laser light as means of creating the mouth of the wormhole. In a publication (R. L. Mallett, “The Gravitational Field of a Circulating Light Beam,” Foundations of Physics 33, 1307–2003), Dr. Mallett argued that with sufficient energies, the circulating light beam might produce closed timelike lines (i.e., time travel to the past).

Is Dr. Mallett’s theoretical foundation solid? According to physicists Dr. Olum and Dr. Everett, it is fatally flawed. In a paper published in 2005 (Ken D. Olum and Allen Everett, 2005, “Can a Circulating Light Beam Produce a Time Machine?”, Foundations of Physics Letters 18 (4): 379–385), they argue three points:

  1. Dr. Mallett’s analysis contains unusual spacetime (i.e., mathematical) issues, even when the power to the machine is off.
  2. The energy required to twist spacetime would need to be much greater than lasers available to today’s science.
  3. They note a theorem proven by Stephen Hawking (chronology protection conjecture—1992), namely, it is impossible to create closed timelike curves in a finite region without using negative energy.

Although Dr. Mallett did not address their criticism in a formal publication, he did argue in his book, Time Traveler, that he was forced to simplify the analysis due to difficulties in modeling the photonic crystal. This, however, is far from a complete response.

Who is right? In the physical sciences, we are judged by the weakest link in our theories. If I use this criterion, I would say the argument favors Dr. Mallett, since the chronology protection conjecture, which we will discuss in the next chapter, has come under serious criticism, and it is not clear that it presents a valid challenge. Nonetheless, Dr. Olum and Dr. Everett are highly regarded physicists. Therefore, at this point, it is hard to know who is right, and right about what. Perhaps the mathematical analysis is flawed, and the approach published by Dr. Mallett requires more energy than is available via today’s technology. However, we are witnessing a significant event in science. A respected physicist, Dr. Mallett, is openly publishing his work on building a backward time travel machine. Other respected physicists, Dr. Olum and Dr. Everett, are entering into a scientific debate regarding Dr. Mallett’s theoretical basis. From my point of view, this is how it should be in science. The debate is healthy. As a theoretical physicist, I know that the debate will end only when either:

  1. The Mallett time machine works, or
  2. The Mallett time machine enters the rubbish pile of scientific failures, along with astronomer Ptolemy’s Earth-centered model of the solar system and the flat Earth theories.

This material is based on my new book, How to Time Travel.