I ran across an article a few weeks ago on the topic of SETI (the Search for Extra-Terrestrial Intelligence) and METI (Messaging Extra-Terrestrial Intelligence). SETI seeks to find evidence of extraterrestrial intelligence through seeking signals from the sky that can be interpreted as possibly containing meaning; METI, on the other hand, a term I had never heard of before, the point is to broadcast a message to the rest of the universe that we are here, so that whoever finds it is aware that there is another intelligent species in the universe. (We have actually been doing the latter unintentionally and with great enthusiasm since the origin of broadcast communication, television in particular.)
As is usually the case with such articles, it was rife with all sorts of speculation, something that tends to annoy me. There is, I think, a legitimate concern about being able to recognize a signal as being from an intelligence once you’ve received it, but there is also concern regarding the medium for communication. As Dr. Morris Jones of METI International points out in a quote from the article:
We are not really sure of how extraterrestrials would communicate with us. Would they use radio waves, lasers, or something more exotic? Perhaps the universe is awash in extraterrestrial signals that we cannot even receive. SETI and METI practitioners spend a lot of time wondering how a message would be encoded in terms of language and content. It’s also important to consider the medium of transmission.
Yes, we do not yet know all of physics yet, and we may never. There may be means with which to communicate to which we are entirely blind because we have not yet discovered or identified the phenomena associated with that medium. While there may be a medium for communication we don’t know about, it seems to me that the METI International team have gone to great extremes to imagine such means. More below the fold.
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As far as I’m aware, SETI has spent decades looking for evidence of communication by searching some portion of the electromagnetic spectrum. For a very long time, this search was confined to radio waves, and for various reasons, from our parochial perspective, it seems most likely that such communications would most likely be found somewhere in this region. However, it’s imaginable that intelligent beings might prefer to use some other portion of the spectrum, for example the visible region, through the use of laser pulses, so we can’t just limit ourselves to one particular region, no matter how much sense it makes to us to do so. This sort of broad thinking is quite useful, I think.
However, things sort of went off the rails (in my opinion) when it was suggested that beams of more exotic particles than photons (light) might be used for communication. In particular, the prospect was raised for using neutrinos for the purposes of communication, which struck me as utterly perverse. Neutrinos are particles with no charge and almost no mass. They carry an intrinsic spin (the same as the electron), and they travel at very nearly the speed of light. The speed of these particles might appear to make them good candidates for communications, but there’s one small problem: they interact only very weakly with any other matter they may encounter. Billions of neutrinos are passing through your body during any second, and by and large, they’re not doing anything. In the very rare instances in which they do interact, they cause a proton to turn into a neutron and an anti-electron (or a neutron into a proton and an electron), and this transition can be observed by the electron or anti-electron flying off and hitting something, causing a flash of light. But in order to detect it and not confuse it with other phenomena that cause such light flashes that are orders of magnitude more common than neutrino interactions, it’s necessary to observe them in media containing tons of matter, preferably under miles of rock, so that other forms of radiation will not interfere with the measurement. And then, depending on the type of neutrino you’re looking for, you might see a few of these flashes per month. There will be little in the way of correlation to which neutrinos interact because it happens pretty much at random. How the heck would it be possible to glean any information from a few random flashes recorded over months? How long would you have to collect data before an identifiable pattern would arise? This is just an insane idea!
Now, I can’t discount that there may in the future be some sort of technology that will allow the detection of neutrinos much more efficiently, but given the weakness of neutrino interactions with matter, it’s an uphill battle. Trying to imagine practical means for communicating with neutrinos is orders of magnitude more pointless than chasing moonbeams. At least you can see the moonbeams!
Then they bring up the possibility of communication through gravity waves! It took 100 years since Einstein predicted there were such waves to the point where they were detected just last year. Thus far, only three phenomena have been observed using the gravity wave detectors, and they were all a pair of black holes merging into one. This tells us it requires the movement of a lot of mass in order to detect these waves, and recently, some have raised doubts as to whether the claimed gravity wave detections were gravity waves at all.
These people need to calm down a little and start being realistic. Stick to the electromagnetic spectrum, ferchrissakes!
Top Comments, (June 29, 2017):
From peregrine kate:
Please consider this one by Bindle for tonight. It came from Jen Hayden's story this morning on 45's puerile attack on Mika Brzezinski. Bindle's comment is long, thorough, and spot-on.
Top Mojo (June 28, 2017):
Top Photos (June 28, 2017):
Tonight’s picture quilt is courtesy of jotter!