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Ask Dr. SETI ®

Chapter 1: Astrophysics

Faster-Than-Light Communications

Dear Dr. SETI:
When a Native American sends a smoke signal today, who hears or sees what is being said? I think the reason we are not having any luck in finding transmissions from other worlds, near or far, is that we are using technology that is current only for us. But what if the inhabitants of some other world are traveling between stars, having developed a system that allows them to travel faster than the speed of light?

If you can travel at warp speed, why would you communicate using a system that propagates at the speed of light? They would need some sort of system that transmits a signal beyond the speed of light.

Oh! People have said we cannot surpass the speed of light, just as it was once felt we could not surpass the speed of sound. I think the speed of light is no different than the speed of sound, just a tad faster. I feel that is where research needs to be done, looking for a method of communication that can surpass the speed of light. Dr. A. Einstein gave us a leg-up on some of this type of knowledge; now we need to find someone that can take this information and run with it, to the most distant star.

Don, San Antonio TX

The Doctor Responds:
Actually, the speed of light is about Mach 1,000,000, or a million times the speed of sound. If that's "just a tad" faster, I'd like to have a SETI League budget which is "just a tad more" than $1! But that's a different discussion altogether.

During one of his last lectures, which I had the pleasure to attend, Dr. Isaac Asimov (who SETI League advisor Arthur C. Clarke eulogized as "the world's second greatest Science Fiction writer") fielded a question about faster-than-light (FTL) travel. Specifically, he was asked if his refusal to write scenarios incorporating FTL travel stemmed from his closed-mindedness about the possibilities of future technology. His reply included an elegant analogy, which I will paraphrase:

Back in 1491, when the world was still flat, people imagined that if they walked far enough, they would fall off the edge of the Earth. Today we know that couldn't happen, because our Earth is a sphere. If you walk far enough you might drown, but you won't fall off.

We all agree that writing a story about someone walking off the edge of the world isn't realistic. It violates a basic law of nature, as we understand it. Accepting that the world is round does not represent closed-mindedness, as no degree of imagination can change that fact. FTL travel is like that. Unless we are wrong about the laws of the Universe (and we could be, but that's just speculation -- we've never seen any evidence to suggest so) it's just not a credible story line.

Not all science fiction authors are so constrained by the laws of nature. Dr. Robert Forward, for example, subscribes to what has become known as "Forward's Law": never let the facts get in the way of a good story. While this philosophy is fine for fiction, it doesn't sit well with SETI. In fact, we embrace what I like to call "Dr. SETI's Corollary to Forward's Law": never let a good story get in the way of the facts.

I for one respect Asimov's analogy, even though it may be a bit over-simplified. Now, what about your own analogy of FTL to the supposed "sound barrier?" Actually, they are not equivalent at all. There was never any scientific law to which anyone was ever able to point which led to claims that we'd never exceed the speed of sound. On the contrary, we had direct physical evidence (primarily from meteorites entering the atmosphere) that the "sound barrier" was not an impenetrable barrier at all! What the general public (and some scientists) did believe is that we would never have the technology for faster-than-sound travel. But that's a very different thing from the light barrier, which is based on physical laws (as we understand them), not limits imposed by our own technological immaturity.

We see here another example of the public confusing technology with science. No advance in technology will ever let us step off the edge of the flat earth, or violate other basic physical laws. Nature is very unforgiving that way. And I hasten to point out that, unlike meteors, which routinely go faster than sound, we have not one shred of verifiable evidence that anything has ever gone faster than light, in nature or otherwise.

So much for FTL travel. But what of FTL communications? Similar arguments apply, but he bottom line is, even if I'm wrong about this, microwave and optical SETI still make good sense. Imagine that there is a continuum of technological development, somewhere on which each of the multitudes of probable civilizations will fall. They are not all at the same level of development, because they are neither all the same age, nor evolutionarily homogeneous. I'm willing to stipulate that some civilizations may have developed technology undetectable, or unrecognizable, to us, or in Clarke's words, indistinguishable from magic. (Maybe some even have FTL travel. Maybe even FTL communications. Though I doubt it. Paramount Studios holds all the patents on Warp Drive, and they're not sharing them.) Are you willing to stipulate that at least some civilizations may still be using, or may have recently (in terms of their light-distance) used, radio?

The reason we "aren't having any luck," as you so pessimistically put it, has more to do with the fact that in all of human history, we've been looking for less than an eye-blink. SETI requires patience, and a multi-generational perspective. It offers little to he or she who demands instant gratification. Even if we bend the laws of nature.

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