Lost in Spacetime

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Fans of ABC's Lost are eagerly waiting tonight's premiere of the final season — and those fans include a good number of physicists, such as Sean at Cosmic Variance. Last week he wrote an entire blog post about the physics of time travel in Lost (it was a major story arc in Season 5) and how the show's writers have adapted some cool ideas in real-world science to creatively develop the series' theme of free will vs predestination.

(Warning: Minor spoilers below.)

Here's one example of how real physics gets woven into the fictional fantasy world of Lost:

In one of the Dharma Initiative orientation videos “Edgar Halliwax” (Dr. Chang) explains that the island contains a pocket of exotic matter, perhaps sustained by the Casimir effect, which lets them conduct unique experiments in space and time. That’s all on the right track. Even though general relativity lets us talk about wormholes, under ordinary circumstances we wouldn’t expect them to be useful for purposes of time travel — even if a wormhole were created, it would collapse to a singularity before anyone could cross it. A hypothetical way out is to invoke exotic matter, which would have a negative energy density and prevent the wormhole from collapsing. And how can we get negative energies? Perhaps from the Casimir effect, which arises when materials alter the energy contained in quantum vacuum fluctuations. Again, it’s not a full-blown respectable and realistic theory of time travel; but I’m happy that the show nods in the direction of real ideas, which will hopefully inspire the occasional viewer to dig more deeply into them.

Here's a bit more detail about the Casimir effect. It's named after Henrik Casimir, the Dutch physicist who discovered it in 1933. Normally two uncharged parallel metal plates would remain stationary because there is no electromagnetic charge to exert a force to pull them together (or push them apart). But Casimir found that if the plates are close enough, there is still a tiny attractive force between them.

Because the parallel plates are so close together, virtual particle pairs can’t easily come between the plates, so there are more pairs popping into existence around the exterior of plates than there are between them. The imbalance creates an inward force from the outside that pushes the plate together slightly. The smaller the separation between the plates, the fewer virtual pairs can get between them, and the greater the force of the inward attraction. 

CalTech physicist Kip Thorne once devised a wormhole model based on the Casimir effect that would enable travel not just through space but through time. Thorne proposed creating two identical chambers, each of which contains two parallel metal plates separated by a very small gap. The electrical field created by the plates via the Casimir effect creates a tear in space-time, so that the chambers become the two “mouths” of a connecting wormhole. Then one chamber is placed on a rocket ship and accelerated to near the speed of light.

Since time is moving at different rates in each chamber due to relativistic time dilation – remember that a traveling clock ticks more slowly than a stationary one – the two chambers become desynchronized. They are still connected by the wormhole, yet they exist in different times. Time has passed more slowly in the accelerating chamber, so a person in the earthbound chamber could step through the wormhole and be hurtled into the past. A similar effect could be achieved by connecting a wormhole between the earth and something very heavy, like a neutron star. This also sets up a time difference between the two ends, since mass warps space and time. A clock on the surface of a very dense neutron star would run about 30% slower than it does on earth.

That's just something to think about as you tune into the season premiere of Lost. In case you need a refresher course as to where we left each of our plucky plane crash survivors, the New York Times has a handy interactive timeline. Because we all know how annoying Lost fans can be when they get started on analyzing the hidden clues and symbols of the series:

Final Season Of 'Lost' Promises To Make Fans More Annoying Than Ever