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When I saw the new ‘alien first contact’ movie Arrival last week, one particular element that made me smile was seeing the alien spaceship leaving Earth basically by dissolving into a cloud or mist. Readers with Fortean tastes will likely be familiar with tales of UFOs disappearing into clouds. For example:

On many occasions UFOs are reported to become gradually engulfed in a vapor cloud. One such case can be found in James McCampbell’s “Effects of UFOs upon people”: A highway patrolman saw a strange object sitting on the ground in the San Joaquin Valley of California. It was early morning on a wintry day. Suddenly, the object became surrounded by a mist. Then a brilliant glow appeared as the object rose off the ground.

And another:

A doctor saw two large disk-shaped objects merge into one, and the single object sent a beam of light in his direction. It vanished with a sort of explosion, leaving a cloud that dissapated slowly.

This ‘dissolving into mist’ factor – along with other elements from UFO sightings – have been discussed at length by some UFO researchers as possible clues to they way in which they travel (although doing so does tend to make the perhaps erroneous leap from ‘UFO’ to ‘spaceship’). However, there seems little consensus, with explanations for the link ranging from the effects of plasma propulsion, to reduced atmospheric pressure surrounding the UFO.

So I was interested today to read polymath Stephen Wolfram’s length discussion of his contribution to the science in Arrival. Wolfram covers a lot of ground, but at one point he does appear to discuss his idea for how the aliens might achieve interstellar travel (an idea which he came up with overnight, surprising even himself):

Maybe the spacecraft has its strange rattleback-like shape because it spins as it travels, generating gravitational waves in spacetime in the process… The gravitational waves would lead to a perturbation in the structure of spacetime, [and] the spacecraft somehow “swims” through spacetime, propelled by the effects of these gravitational waves. Around the skin of the spacecraft, there’s “gravitational turbulence” in the structure of spacetime, with power-law correlations like the turbulence one sees around objects moving in fluids. (Or maybe the spacecraft just “boils spacetime” around it…)

So there you go UFO researchers, there’s another possibility to add to your list of propulsion theories!

There’s much more of interest in Wolfram’s blog post, I recommend it for anyone interested in high-concept scientific thinking about the alien contact scenario. And one particular passage stood out to me, not so much because of the ‘alien’ concepts discussed, but a very human one. These days, it often seems to be the case that ‘speculation’ is a no-no in scientific thinking – “stick to the facts”. But Wolfram points out how liberating it felt for him to explore how ‘the impossible’ might be achieved:

It’s fun for an “actual scientist” like me to come up with stuff like this. It’s kind of liberating. Especially since every one of these science fiction-y pieces of dialogue can lead one into a long, serious, physics discussion.

I think there has to be room for plenty of speculation in science – it’s just a case of communicating clearly to others that you are doing so, rather than suggesting something as a certainty.

Link: Quick, How Might the Alien Spacecraft Work?

Further reading: Your Choice of Starships (at Centauri Dreams)