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Time Travel

Back to the Future.

Sorry, McFly. The technology to send you back in time isn't ready yet.

A century ago if you had predicted the existence of the internet people would have thought you daft. 50 years ago a suggestion that soon enough everyone on the planet would carry a personal telephone would have marked you as a raving lunatic. Ten years ago to suggest that creating Harry Potter’s invisibility cloak was actually possible would have merited a laughing spell.

Conclusion? Never speculate about what science can’t accomplish, no matter how farfetched it may seem at the time.

The web and cell phones are now completely ubiquitous. Even the seemingly unlikely invisibility cloak is closer to reality than skeptics might have expected. (See my post about “metamaterials” that can render material objects invisible). 

But what about time travel, that hoariest of science fiction themes? Our current understanding of the laws of physics isn’t encouraging of travel backwards in time. Forward travel might be consistent with some interpretations of the theory of special relativity but would— fortunately or unfortunately—be irreversible. Thus, getting rich by observing tomorrow’s stock market is not currently in the cards.

Some physicists have speculated that a way to relax the constraints against time travel would be to demonstrate faster-than-light travel. A sticking point is that Einstein produced the equation showing that nothing with mass can travel faster than the speed of light because its mass would become infinite. But the tentative discovery a few years ago of superluminal (faster than the speed of light) propagation of light itself in certain galactic structures raised a tiny hope for time travel.

That hope is now dashed. A team in Hong Kong demonstrated that even a single photon cannot exceed the speed of light. {Phys. Rev. Lett., 17 June 2011, 106, 243602}This thrashes our best existing prospect for travel to other times. Chemists would never squelch our imaginations so, but physicists apparently don’t mind.

Related:
Episode 94: Scientific Visions [Distillations]
Episode 25: The Chemistry of Time [Distillations]

Posted In: Technology

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