How should the media react to news of a claim of detection of alien intelligence? Claims come with various degrees of credit—there is some threshold that needs to be crossed for it to be worth repeating.

With earthquakes, the media can get a quick sense of importance from the Richter scale, which reduces a lot of qualities into a single number that the press has more-or-less learned how to use. Combined with location, even a non-expert can quickly use the scale to make a good guess about whether the earthquake warrants a call to see how loved ones are doing.

The Torino Scale

There is an analogous scale for asteroid threats.

It’s not very often that we have one, but when one is reported there’s generally a range of reactions in the media from totally ignoring it to overhyping how the world will end soon. Fortunately, responsible journalists can look to the Torino scale to see how newsworthy a potentially hazardous asteroid is.

In short, the worry of an impact is some combination of the likelihood of impact and the damage it would cause if it hit. A number above 3 is newsworthy, a number above 5 is genuine cause for concern and deliberation, and anything above 7 is call-Bruce-Willis territory.

In the history of the scale, only there have only ever been 2 asteroids that even reached Torino 2, and only one of those was (briefly) upgraded to Torino 4. Both were quickly downgraded to zero upon further measurements. The media can, if they care to be responsible about this, generally ignore anything that is Torino 0, except maybe as a hook for a think-piece on planetary protection or something.

The Rio Scale

What about SETI? SETI has the Rio scale, set up by the International Academy of Astronautics at a conference in Rio to help the public understand how excited to get about “signals” from space. Seth Shostak has a nice formula to help one calculate it here, and there is a calculator here. It’s not perfect — it assumes that you understand the nature and origin of the signal you’ve detected — but it does help put things in perspective.

The Rio scale is a 10 point scale that multiplies the credibility of a report (a 5-point scale from 0-4) with the sum of scores from the class of phenomenon (from 1-6), type of discovery (from 1-5) and the distance to the source (from 1-4, important since it goes to whether two-way contact might occur).

Let’s take two famous examples to get a sense of scale: the Wow! signal and Tabby’s Star.

The Wow! Signal

The Wow signal is the most famous unexplained, potentially alien radio signal from space, detected 13 days after I was born in 1977 by Jerry Ehman (there have been many such “one-off” signals detected).

The class of phenomenon here is unclear—there’s no reason to think it was intended for Earth or could be interpreted by us. This gives it 1 or 2/6 on this portion of the scale.

The discovery type is also low — a one-off signal. This gives it a 1 or 2 /5 on the second portion.

The distance is unknown because we only have a general direction that it came from— so we only get the minimum 1 point out of 4 here (I think).

Finally, there’s the credibility: professional radio astronomers who understand their equipment well believed they found something. In my mind, that puts it up to a 3 or 4/4 on the reliability scale.

Following the formula, I get somewhere from 1 to 3 on the Rio scale for this signal — not bad, and commensurate with how it’s talked about. It’s a neat signal!

Tabby’s Star

What about Tabby’s Star? Plugging in the numbers again:

Class of phenomenon is low: there is no communication here, just possible evidence of astroengineering: 1/6

Discovery type is unclear, but since Kepler saw the dips for years and we’ve ruled out instrumental effects, let’s be very generous and give it the full 5/5.

Distance is well-known: 1,500 light years or so. So we get 2/4 on this one.

Credibility on the report is high, but at some point we also to include our confidence that the source was not natural, which is low. We still have natural explanations to rule out. Let’s say 2/4 (“Possible, but should be verified before being taken seriously”)

Plugging everything together, we optimistically get a 3 on the Rio scale, which is pretty high as these things go (which is why it gets attention from the SETI community). But this optimistic number is somewhat subjective, so it’s clear why many astronomers give this explanation no credence. A reasonable person might give much lower numbers to these categories and give it a 1 or 0. The point is, it’s analogous to those near-miss asteroids: interesting enough for a popular article (or blog post) for lay aficionados, but anything more than that is unwarranted hype.

Unconfirmed Signals

Now, let’s imagine a hypothetical discovery of “something weird” in some archival data of some distant stars. The “something weird” matches their pet theory for how aliens might communicate among each other, but the discoverers are not the people who took the data, and have not consulted with such experts to see if it could be an instrumental effect. They have also not gotten verification that the signal is seen with other instruments. So:

Type of phenomenon: intercepting undecipherable communication: 2/6

Discovery type: from archival data, no verification: 1/5

Distance: in the galaxy 2/4

Credibility: Instrument experts have not weighed in yet: 1/6 (“very uncertain, worthy of verification”). Also, “something weird” does not rule out natural explanations, so lower it down again to maybe 0.5/6.

Plugging things in, we get 0.4 on the Rio Scale. Most astronomers can ignore it, the press should definitely ignore it, but someone should probably follow up, just in case.

Another perspective

I’m not a big fan of the Rio scale because, as you can see if you try it yourself, if you have a signal you don’t understand, it’s hard to put on the scale. The possibility it might be natural or instrumental is not really a parameter, so I’ve forced it into the “credibility” and “discovery type” categories in my examples above.

Rather, I prefer this sort of sequence for “something strange” detections. Every step of the way a detection gets more interesting from a SETI perspective:

Point to a prediction of such a signal in a SETI context. Not every weird thing is interesting from a SETI perspective. Rule out instrumental effects. This can be done by using a different instrument to detect the same signal, or thorough analysis of the data by experts in that instrument. Rule out obvious natural or terrestrial explanations. This means showing that any natural explanation is extremely unlikely or physically impossible.

Most “signals” discovered in SETI top out on this sequence at steps #1 or #2. Optical and radio searches find “interesting” “signals” all the time, but they expect a few statistical flukes and equipment hiccups from time to time (astronomers like to blame “cosmic rays”, which are real examples of so-called “gremlins” that sometimes cause electronics glitches). Those that are probably real usually don’t repeat, and so it’s hard to rule out natural or terrestrial phenomena that we don’t understand if we can’t see it happen again (like the recent RATAN-600 “detection”).

But if you do get this far— the signal repeats, it’s definitely seen with other instruments— it’s very interesting! You’re in the same space now as the discovery of pulsars, GRBs, FRBs, and quasars. Note that all four of those discoveries were very interesting natural phenomena, but the SETI community was rightly interested in them until they were solved. There have probably been many other “discoveries” that got this far and turned out to be not so interesting as those four game-changers (Tabby’s Star will probably end up in that category).

At this point, if all you have is “something weird” and not a clear, deliberate signal, you still have work to do before claiming a “probable” discovery of aliens, but you are at the point that you should tell communication SETI people that they should consider pointing their instruments at your target, just in case. Then:

See what the reaction is from the community of astronomers by getting the discovery published in a peer-reviewed journal. This will get more eyes on the data, and help determine if you’ve missed anything. At this point, the press may be rightfully interested—you need to point out to them that it’s probably not aliens. Learn more about your targets. Brainstorm less-likely natural explanations. Organize campaigns to follow it up

At this point you might be a 3 on the Rio scale. Beyond that, you’re in terra incognito, and if the source resists natural explanation you might creep up higher on the Rio scale, slowly.

If you are sure that you have something that looks like communication from alien intelligence, then you can calculate a proper Rio scale number, but you also go farther along this sequence, following the generally accepted protocols for an ETI signal detection:

Rule out all forms of terrestrial and natural origin for your signal, including hoaxes. Get confirmation from independent researchers of the signal using different equipment, and set up continuous monitoring

In other words, only if you find and confirm extraterrestrial signals of unambiguously intelligent origin—impossibly narrow-band radio signals or impossibly-brief laser pulses, for instance (impossible for a natural source, I mean)—do you claim any level of certainty of the detection of alien life. At this point a researcher can contact national authorities, the international astronomical community, and start planning for how to manage the press.

So, the press should certainly publish when a researcher gets to the sixth step of this sequence, but anything at an earlier stage is a curiosity for those interested about how the process works and what SETI researchers are interested in these days. Anything before step 2 is just the usual background rate of (presumably) false positives, and responsible journalists should generally ignore it.

[Edit: I have another attempt at a scale, so I’ve tweaked the description of my sequence in this post to avoid confusion with that one.]