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Time Travel Possible

Could time travel, as in the movie Back to the Future, be more than a science fiction fantasy? A group of physicists at the University of Queensland in Australia are convinced that it is indeed possible in some way.

In a recent experiment the scientists simulated how time-traveling photons might behave. At the quantum level, at least, they argue, the so-called ‘grandfather paradox’ could be resolved.

In the ‘grandfather paradox,’ a person who travels to the past and kills his own grandfather, would block the existence of his father or mother and therefore himself. The time-traveling character played by Michael J. Fox faced similar challenges, but thanks to movie magic, was able to overcome them.

In their simulation, the Australian researchers studied the behavior of a photon traveling through time and interacting with its older self. Employed was a closely related, fictitious, case where the photon travels through normal space-time and interacts with another photon stuck in a time-traveling loop through a wormhole, known as a closed time-like curve. Simulating the behavior of the second photon, the researchers were able to study the behavior of the first. The results showed that, when the second photon is prepared in just the right way, consistent evolutions can be achieved.

In other words, it is possible that the murdered grandfather’s existence could both continue and not continue. To avoid headaches, don’t meditate for too long on this theory.


Near Light Speed Doable

The idea of speed-of-light travel comes mostly from science fiction. Shows like Star Trek have introduced us to concepts like ‘warp speed’, but how real could such ideas be? More than you might have once thought (see the EmDrive story on page 10). In fact, a respected new mathematical theory argues that some day we should be able to build a photon-powered rocket that will be able to reach speeds of 99.999% of the speed of light.

A Norwegian professor is arguing in the Journal Acta Astronautical that even though it won’t happen anytime soon, the potential is there to build a spacecraft, which could get very close to light speed.

A professor of quantitative finance at the Norwegian University School of Life Sciences, Espen Gaarder Haug, explains in his paper we are already using photons as driving mechanisms, and he shows that if you follow the developments suggested by such technology, you can end up with a craft that could do it in deep space. Haug is sticking to the laws of natural physics, as science currently understands them. Unfortunately his plan indicates we would need particle accelerators with the kind of energy used in the Large Hadron Collider. So don’t hold your breath.

Some of us are holding out for quantum bilocation. You get where you need to go but you don’t have to leave where you were. If it was good enough for the saints, it’s good enough for the rest of us.


Cheap Water from Air?

For a world desperately in need of water, help could be on the way. Soon, thirsty people everywhere may be able to drink from a small box capable of drawing water directly from low-humidity air. Complex technologies previously on the market have required high humidity to do the same thing.

According to an April report in the journal Science, researchers at M.I.T., have created a ‘box’ that can, in areas where the humidity is only 20–30 percent, easily yield several liters in 12 hours.

The secret is a powdery sand that traps air in its tiny pores. When heated by the sun or other source, water molecules in the trapped air are released and condensed—in other words, water is drawn directly from the air. No complicated refrigeration-cycle technology is needed.

In a few years, it is thought, it will be possible to mass produce the technology and, at low cost.