Spaced out

Not quite the witty title I wanted, but it fits the theme.

I missed this story when it came out, but it’s newsworthy because it’s a very low-probability event: a 14-year-old boy was struck by a meteorite last year.

Next, we have a claim that space aliens may not be friendly. Is this news to anyone? Besides peace-and-love-and-crystal-harmony types, that is? It’s not like there haven’t been books and movies addressing the topic before. Given the history of war between different tribes and nations, why would anyone presume that aliens would necessarily be peaceful?

One quote from the article is worth a little discussion:

Some scientists are puzzled as to why no messages have been sent back even though humans have been transmitting radio and television signals for the last century.

That’s actually a pretty stupid thing to be puzzled about. First, that would require another intelligence within 50 light years, and further presumptions that:

  • They received the broadcasts and recognized them as a product of intelligence immediately.
  • They deciphered them immediately.
  • They decided to send a response immediately.
  • They had the equipment available immediately for sending that response.

Just coming up with some simple points for each of the above:

If they’ve got equipment to receive us, they’ve probably got equipment to send back, so that’s not necessarily a big objection. They may have reasons for not wanting to use it, or to broadcast at the necessary level to reach us. Then again, perhaps they have already responded to us, and we didn’t recognize it as a response, because it’s using a technology that they expected us to develop in the meantime.

It’s probably moot, though. A few months ago, I read an article that said that our broadcasts would sink into the background noise within some distance that I don’t remember, but was shorter than I expected. I couldn’t find a link to it to put in this post, but I did find this, which makes the same point. We do have equipment that can pull signals out of the noise, even if the noise is louder than the signals, but in that case, we know what kind of signals we’re looking for. That’s a lot different than, “There may be a signal here. It may be hidden below the level of the noise, and we have no idea what it looks like.” Searching for it in those conditions is a good recipe for ongoing employment, but not necessarily for success.

It may be moot for another reason, though. Technology marches on, and the changes and improvements have side effects. When I was younger, I used to see billboards across the southwest for radio station XERF, broadcasting from just across the border in Mexico with 250,000 watts of broadcast power. They were in Mexico because, among other reasons, it freed them from FCC restrictions on broadcast power. My understanding was that atmospheric skip meant that they could be heard across most of the US, at least at night. Recently, I’ve been hearing about low-power FM and neighborhood radio. Lower-power signals means a shorter propagation distance before it falls into the background noise.

In the early days of personal computing, back in the 1970s, I read about how some people were using AM radios to debug their programs: the switching frequencies of the digital signals in the computer fell into the AM range, so tuning between stations would let you hear a series of shifting tones that related to what the application was doing. In the days when some people only had lights and switches for I/O, that could be an important diagnostic technique. Nowadays, computers operate well above the AM range. They take less power (sometimes absolutely, sometimes merely relatively) than they used to, as well. I work in the field of embedded computing; Intel’s 80188 processor, which used to be popular for the purpose, consumed 800 milliamps if you were using the NMOS part. The MSP430 from Texas Instruments can require as little as a couple microamps. That’s not going to generate much in the way of radio signal.

So, I guess what I’m saying here is that it’s pretty unlikely that aliens shot the rock at the kid.

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