| Subject: Re: What is SETI? was->>Re: How smart are SETI@homers? - Scientific American |
| From: Joseph Lazio |
| Date: 05/05/2004, 00:39 |
| Newsgroups: sci.astro.seti,alt.sci.seti,sci.space.policy |
"R" == Rich <someone@somewhere.com> writes:
R> In infinite wisdom Christopher M. Jones answered:
Rich <someone@somewhere.com> wrote in message
news:<4096BAF0.9050408@somewhere.com>...
I'm reminded of discussions I had with an ex-roomate who was into
magic. Despite a tower of theories explaining why magic works
(...), he was somewhat aggravated when I suggested that first he
needed to show *that* magic worked. [...]
SETI is in a similar position near as I can tell.
Utterly wrong. SETI is not about finding extra-terrestrial
civilizations per se,
R> It's not? Boy did I misunderstand the acronym. So then what *does*
R> 'SETI' stand for?
This somewhat provocative statement by Christopher was meant to catch
the reader's attention.
it is about scientific research into the abundance and nature of
extra-terrestrial civilizations.
R> How can you research something when you got zero examples to
R> research?
R> Answer: You can't.
Let me rephrase his statement: SETI is an effort to investigate the
number of ET civilizations. One can certainly conduct research into
the question, How many examples of X are there? where X is ET
civilizations, species of neutrinos, organisms that can survive in
extreme environments, etc.
Failure to find strong evidence of ETI in any given SETI program is
not a failure of the program, it is a scientific *result*.
R> I'm amazed at how many think that you can derive population
R> statistics from one example, the earth.
Re-read what Christopher wrote. He does not advocate deriving the
number of ET civilizations based on the Earth, but searching for other
ET civilizations to derive population statistics.
Sufficiently well constructed and well executed SETI programs that
produce a negative result provide critical data defining boundaries
on the abundance and nature of ETIs.
R> You cannot derive meaningful boundaries for something
R> undetected. You cannot research something you've not found.
R> And you can search for a million years for anything that does not
R> exist, refining your so-called boundaries again and again, but you
R> ain't doing science.
Sure you are, and that's the point. Take something we all know to be
"true." What's the mass of the photon? It's 0 eV, right? Well, no.
The mass of the photon must be less than something like 1E-48 eV.
That's consistent with 0 eV, but doesn't mean that it must be exactly
0 eV. Suppose somebody devised an experiment that could lower this
upper limit to 1E-60 eV (to make up a value), would the experiment be
worth doing? Yes! The payoff from finding that the mass of the
photon was greater than 0 eV is immense, even though everybody would
expect that we'd just be pushing back the boundary.
By the same token, we can already set simple limits on the number of
ET civilizations. There are clearly no super-advanced civilizations
(e.g., Kardashev Type II civilizations) in our neighborhood radiating
at huge power levels or we'd have seen them already. Current SETI
programs are attempts to do this with a bit more sophistication. What
about less advanced civilizations? How many of those might there be
around us?
If you'd like to read about an early attempt to set limits on the
number of civilizations in the Galaxy, visit the ADS and take a look
at the paper by Horowitz & Sagan (1993).
To obtain hard boundaries on ETI parameters it will be necessary to
perform a wide variety of robust search programs using a wide
assortment of techniques (...).
R> [...]
R> I submit that you cannot do science on anything that cannot be
R> detected, regardless of whether it exists or not. SETI is not
R> science, it's not studying 'something', rather, it's looking *for*
R> something, something as yet undetected.
But that's the point! *We* can be detected over interstellar
distances. Look at the FAQ. Some of the transmissions we produce
already can be detected over interstellar distances.
Let me turn your statement around. How do you know that the Galaxy
contains no other civilizations, given that we know of one
civilization that can be detected over interstellar distances?
[...]
Compare this with extra-solar planet studies.
R> These are actual studies, real science, and we have real results,
R> not bogus and fraudulant statistics paraded as science.
You seem to have forgotten the many years of searching for planets
when nothing was found. A quick search of the astronomical literature
shows people were conducting searches for planets at least 30 years
ago. Why did they bother? After all, 30 years ago we didn't know of
any extrasolar planets.
[And just a few other comments]
R> I'm not so sure about that. The dataset is still very small. It's
R> not clear, for example, that metal poor stars can have planets, or
R> perhaps planets not gas giants. There are whole populations of
R> stars that are metal poor, especially the populations of globular
R> clusters.
See the recent results on the planet detected around PSR B1620-26, in
the globular cluster M4.