Sending data-rich broadband signals between the stars is no easy matter. Interstellar gas has the effect of disrupting such signals, the result varying depending upon the frequency. Narrow-band signals are easy, broadband hard. But Seth Shostak reports on galactic Wi-Fi, looking at Swedish work that exploits orbital angular momentum, a ‘twisting of the wave’s electric and magnetic fields,’ that may allow much more information to be encoded in the same signal without the disruption that distances in the hundreds of light years invariably impose. One signal becomes a cipher for another, with obvious SETI implications.
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New Scientist (behind its firewall, alas) looks at the work of Alexander Shatskiy (Lebedev Physical Institute, Moscow) on how to detect a wormhole. Shatskiy’s paper “Passage of Photons Through Wormholes and the Influence of Rotation on the Amount of Phantom Matter around Them” (abstract) makes the pitch that something called ‘phantom matter’ could hold the mouth of a wormhole open. Possessed of negative energy and negative mass, such matter might be detectable because it would create optical effects opposite to those of gravitational lensing.

A wormhole signature? Light moving through the wormhole from where/whenever should emerge as a bright ring, while stars behind the wormhole would shine through the middle. All of which reminds me of the classic paper by John Cramer et al. (“Natural Wormholes as Gravitational Lenses,” Physical Review D March 15, 1995. pp. 3124-27), which likewise speculates on wormhole signatures, though with a different result. The paper argues that when the wormhole moves directly in front of a light source, a halo would form around it. What you get when a wormhole occults a star is first the spike, then the halo, then a second spike, a characteristic signature indeed for astronomers lucky enough to spot it.

The difference between the two descriptions is a reminder that we have no idea whether ‘phantom matter’ or a negative mass cosmic string of the sort the Cramer paper discusses even exist. Astrophysicist Geoffrey Landis, a co-author of the Cramer paper, told me several years back that the attempt to identify a wormhole is purely speculative, but surely worthwhile:

“We published our paper on this because people are actively hunting for gravitational lenses with spectrophotometers that can track these effects. We wanted to say, keep your eyes open for this particular signature. You probably won’t find it, but if you do, it would be our first evidence that wormholes actually exist.”

And if they do exist, wormholes open startling possibilities for moving through space and, conceivably, time. Once the excitement of such a detection wore off, the tricky realities for those thinking in terms of fast transit would emerge: If we were to prove a wormhole existed, how would we get to it in the first place? How would we know where or when it led? Even so, a demonstration that at least a few wormholes (created, presumably, in the Big Bang) had somehow managed to stabilize themselves through some exotic mechanism and might still offer gateways to elsewhere would be one of the great results of science.
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The 39th Carnival of Space is available at Visual Astronomy, where Sean Welton has harvested recent space-related materials. Of particular interest to Centauri Dreams readers is Phil Plait’s entry on asteroid 2007 TU24, with a useful and obviously necessary (judging from the bogus information that has floated around the Internet about this object) video explanation of why it poses no current threat. The frustration for those of us who worry about long-term dangers from Earth-crossing objects is that the public reaction is all too easily polarized between disinterest and panic. Isn’t prudent planning a better response?