Most of us will have at some point have bought a long power cable to charge the bike on the deck, but [Slava G. Turyshev] has a slightly more ambitious idea. In this recent paper, he outlines how an advanced civilization could use a star or two to transmit power or send signals over an interstellar distance. And his idea is also simple enough that we could do it right now, with existing technology, or detect if someone else is doing it.
Gravitational lensing is where a large mass (such as, say, a star) bends the path of light around it. That can act like a lens in a telescope, focussing light that would otherwise be impossible to see. Imagine, say, a very, very distant star and a cluster of galaxies: if things line up just right, you could see the light of a star from early in the life of the universe. [Turyshev] speculates that this effect could be used on a smaller scale to transmit power. Well, a smaller scale involving a couple of stars, that is.
The idea [Turyshev] ponders here is that if you plonked a giant laser at the right distance from a star, you could use the gravity of the star to direct the beam, creating a focus point at a certain distance. The gravity of the star acts to focus the beam. According to his work, the system gets more efficient if you take the next step and use a couple of stars to focus the beam, rather like using multiple lenses to improve a telescope, because the spreading of the beam gets smaller with multiple elements. However, [Turyshev] calcuates, this might not work because the second star also lenses the light from the first, so it would be more difficult to filter out the wanted radiation from the background noise of the first star.
The paper also raises the idea that someone might be already doing this out there, and he speculates that this might be an interesting way to contact or detect aliens. If someone is doing this to send signals or energy, then it would be possible to detect with even a moderately sized telescope. The technology is also not particularly difficult: we could, with existing technology put a signal source at the right distance from our own sun to send a message:
Concluding, we would like to mention that the results obtained here, could have a profound effect for applications aiming at interstellar power transmission. Not only we can look for transmitted signals using modern astronomical techniques, we may also transmit such signals with space-based platforms in the focal region of the solar gravitational lens (SGL) using technologies that are either extant or in active development.
[Via Universe Today]
Header: NASA Goddard Photo and Video, CC BY 2.0.
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