Chapter 6 – Time travel and the speed of light

Beyond the Rest of Us –Chapter 6 of the book finds Janet and the pilot Lindsay on her private jet flying out to the Caribbean. This plane has been equipped with a DNA computer in order to try and avoid the military spy satellites, which can track anything on the surface of the planet. Janet uses her time travelling medallion to move just one day through time, but her son engages the dimensional device with disastrous results:

Lindsay could see the plane flying down a tunnel with flashes of light on either side of what looked like a wormhole. There was no sound of the aero- engines and no sense of any time. The plane was now flying in a vortex of energy, just as Janet had seen below the Khufu pyramid. The children were almost floating beside her and the pearl decoration on her top was glowing in the dark. Suddenly there was another bright flash and the darkness ended. Looking out into the cockpit, Janet saw the plane was once again in the open, flying in a blue sky but with a black sea down below.”

In order to time travel a person would have to move faster than the speed of light, which is not as far-fetched as it may at first appear. There are some particular loopholes to this, one of which is the speed of a particular spacetime frame, which can surpass the local speed of light relative to other inertial frames of reference. Some explanations were provided by William Brown, Biophysicist and Academy Faculty member at the Resonance Project:

“Superluminal velocities (speeds greater than the speed of light, c) would result in travel “back in time”. In addition to facilitating effectively faster than light travel, wormholes could potentially be used as time machines, in the following sense first developed by Caltech theoretical physicist Kip Thorne. Imagine an advanced technology capable of creating, manipulating, and containing both ends of a stable, traversable, wormhole. Place one end in a laboratory on Earth and the other on a spacecraft capable of traveling through space at some reasonable fraction of the speed of light. Imagine the wormhole connecting the lab and spaceship is created in some future year, say 2500. Now keep one end on Earth and send the spaceship off in any direction at some appreciable fraction of the speed of light for a finite duration after which it will decelerate, turn around come back to Earth, and stop, so the wormholes ends are brought back together. Relativity tells us that the clocks of observers left on Earth and those in a relativistic moving spacecraft will begin to differ by an amount that depends on the speed of the craft. Since moving clocks run slow in relativity, a spaceship observer might experience a short subjective duration of say, a few weeks, but thousands of years could pass in the external universe depending on how fast they were traveling. In this sense, time travel to the future is easy, and does not require wormholes, just a ship capable of moving at relativistic speeds. A spaceship executing the above manoeuvre might find itself thousands of years in the future after stopping. Yet an observer at the wormhole mouth in the laboratory on Earth would still have its clock synchronized with the shipboard wormhole. If the ship finds itself, say in year 3500, after returning to Earth, any observers on the ship could return to the year 2500, traveling 1000 years into the past, simply by stepping through their shipboard wormhole back into the laboratory on Earth. In this way, wormholes could theoretically be used to travel into the past.”

See – Wormholes, Time Machines, and the Weak Energy Condition for more – http://authors.library.caltech.edu/9262/1/MORprl88.pdf