Tag Archives: time travel

Time travel isn’t possible

Better shelve that plan for a timehopping cultural tour of Renaissance Venice; physicists from the University of Hong Kong are convinced they’ve shown time travel to be impossible.

The possibility of time travel was raised 10 years ago when scientists discovered superluminal – or faster-than-light – propagation of optical pulses in some specific medium, the team said. It was later found to be a visual effect, but researchers thought it might still be possible for a single photon to exceed light speed. Du, however, believed Einstein was right and determined to end the debate by measuring the ultimate speed of a single photon, which had not been done before.

“The study, which showed that single photons also obey the speed limit c, confirms Einstein’s causality; that is, an effect cannot occur before its cause,” the university said.

I’ll give it a maximum of two years before someone has a counter-theory that makes it possible once again…

Time travel without the paradoxes?

A new theory based on quantum mechanics promises to do away with the “Grandfather Paradox” that supposedly makes time travel impossible [via BoingBoing]:

Quantum mechanics seems to allow for such simultaneous computations of all possible outcomes theoretically, though actually making it happen is another issue altogether (such quantum computing would blow conventional computing methods out of the water). But combined with quantum teleportation – using quantum entanglement to reproduce a quantum state in space that previously existed at another point in space – MIT’s Seth Lloyd and colleagues say you can theoretically teleport a particle back in time.

This form of theoretical time travel solves two major problems associated with the feat. For one, it doesn’t require the bending of spacetime as most time travel theories do. Considering the conditions necessary to bend the fabric of spacetime might only exist in black holes, that’s a good thing. But further, due to the probabilistic laws of quantum mechanics, anything this method of time travel allows to happen already had a finite chance of happening anyhow. That means a particle can’t really go back and accidentally destroy itself.

Note that this applies to subatomic particles and not people… so we’ll not be letting time-travel stories through the Futurismic fiction selection process just yet. But as soon as we get confirmation that it’s genuinely possible we’ll send someone back to retrospectively amend the guidelines, which will have the knock-on effect of ensuring all time travel stories submitted to us that were otherwise suitable for publication were, in fact, purchased and published. Can’t say fairer than that, can you?

Bonus quantum mechanics news: a recent successful run of a “triple split” experiment has provided evidence to support the theory of quantum mechanics that was originally developed from the double-slit experiment, first performed over a century ago. If you’re hoping that’ll make quantum mechanics make more sense, however, I suspect you’re all out of luck.

The Adventures of Phil Wade

[based on a true story, Sarah tells me – Ed.]

The Adventures of Phil Wade - Does Not Equal

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