What Do You Say to An Extraterrestrial?

December 2, 2004
by Seth Shostak - Senior Astronomer

I once thought that worrying about what we should broadcast to extraterrestrials made as much sense as fretting over the small talk I’d venture with King Carl XVI Gustaf if I won the Nobel Prize. I reckoned there was no need to dwell on the problem, as it was both hypothetical and irrelevant.

Well, I’ve changed my mind. Not about the chances for a Nobel Prize, but about the value in devoting some cerebral CPU cycles to the matter of interstellar messaging. Part of this shift is due to my colleague at the SETI Institute, Doug Vakoch, who has penned a number of erudite articles on the problem. A few of his insights have managed to percolate through the walls that separate our offices. In addition, new telescopes being built for SETI will soon speed up our search by factors of a hundred and more. So it’s entirely possible, in my view, that we could retrieve a message from another world within just a few decades. Suddenly, the idea of “talking back” would become more than just a wry, dry academic straw man.

There’s also the enticement that pondering what to say and how to say it might help snag that extraterrestrial signal in the first place. It could give us a clue as to what we’re looking for.

....


Click in Picture for larger Version

The bandwidth for interstellar messaging does not have to be low, however. At microwave radio frequencies, you could easily send a megabyte a second. At infrared wavelengths, you could up the bit rate to a gigabyte per second over long distances, and a hundred times more over shorter spans (say less than 1,000 light-years). These transmission speeds are largely set by the dispersive effects of the hot gas that fills interstellar space, and they vary a bit depending on direction and wavelength. But the point is, there’s no need to skimp on the information you transmit to cosmic listeners. The data pipe is fat.
...
The difference between Samuel Morse’s first, terse telegraph message and the bit stream spewed by a modern telecommunications satellite is enormous. Keep that in mind when you think of contacting other societies with something akin to the Pioneer plaque. Sure, that gold-plated greeting card was a great start, but if we’re really thinking about interstellar messages, we should think big.

read the very interesting Story What Do You Say to An Extraterrestrial?

Sir Ulli