The Sun's gravity could be used to create an interstellar communications networkS

The Sun's tremendous gravitational pull actually warps the fabric of space around it, creating focal points where light comes together. We could use these focal points to build the most powerful telescopes ever and communicate with spaceships in Alpha Centauri.

General relativity tells us that the Sun's huge mass actually warps the space-time around it, which in turn bends the light passing around it. This creates focal points away from the Sun where the bent light converges, in much the same way a lens can focus all the light that passes through it onto a single point. If we were to put a detector at one of these focal points, all the image and information drawn from the light passing through would be intensely magnified, instantly creating an extremely powerful telescope.

Now, the nearest focal point isn't anywhere near Earth - about 550 astronomical units away, or 550 time the distance between Earth and the Sun. For the sake of comparison, Neptune is only 30 AU away, while the Kuiper Belt only extends out to 55 AU. Still, by comparison to the solar system's really distant objects, like the Oort Cloud, which is perhaps as much as 50,000 AU away, 550 AU doesn't seem so bad. Still, it's much further than any previous human exploration has taken us - the Voyager probes are still only about 100 AU away, and it's taken them nearly four decades to get that far.

So, setting up a detector on one of these focal points is possible but very difficult. But what will we get out of it? Well, a detector could pick up great magnified visible light as well as other types of radio signals. This would allow us to view distant objects with the kind of clarity the Hubble Space Telescope could only dream of, and it might just give us the sort of resolution necessary to get a good look at Earth-like planets around other stars.

The Sun's gravity could also massively boost our communications abilities. We would be able to keep track of deep space probes for far longer and with far more clarity than we're currently able to. Right now, the Voyager probes remain in contact using the Deep Space Network, NASA's powerful communications array. It still works OK over billions of miles, but even communicating with a spacecraft orbiting the nearest stars would probably be impossible with the current technology.

Experts estimate that, over the 26 trillion miles between us and the Alpha Centauri star system, various forms of space noise like the cosmic microwave background radiation would interfere with signals, scrambling as much as half of all transmissions. That sort of error level would be a massive stumbling block for any interstellar probes, even if they sent the same messages over and over again.

The alternative would to be to build an interstellar radio bridge by placing another detector at a focal point around Alpha Centauri. That means the first mission to Alpha Centauri would just be to allow ourselves to make contact. Once the detectors around the Sun and Alpha Centauri start communicating, the error rate in transmissions would drop from 50% to .00005%, the same error rate the Deep Space Network currently has within our own solar system. Amazingly, the interstellar radio bridge would operate with a tiny fraction of the power it takes to run the current DSN.

This also gives up a possible new approach in the search for extraterrestrial intelligence. An advanced alien race might well set up a radio bridge between its own star and its stellar neighbors, and if the Earth was positioned just right with respect to the two communication points, we might be able to listen in on the alien conversations.

There is one major drawback, however. The two sides of the radio bridge would need to be extremely precisely aligned, and currently we don't have the technology to maintain that level of accuracy over light-years. We do know of a possible theoretical solution: a sort of galactic GPS powered by intensely magnetized neutron stars known as pulsars. And besides, even with the bridge in place, the messages still won't travel faster than the speed of light.

Even so, for all these caveats, this is still fundamentally a highly awesome idea, and a pretty cool piece of tech to throw into your slightly more realistic space-based science fiction. It's going to take us a lot longer than we'd like to reach the stars, but at least we'll be able to clearly announce our arrival when we finally get there.

[via; image by Claudio Maccone via]