From: William Edmondson (w.h.edmondson_at_cs.bham.ac.uk)
Date: Tue Sep 28 2004 - 13:41:59 PDT
Hi Paul, Elisabeth
I was at the meeting too - it was a good meeting.
I think the concern to find unambiguously artefactual signals is
important. In the pulsar based search scheme I have proposed with a
colleague (see previous emails) this is one of the points we make. It
is indeed possible to define certain signal characteristics from certain
locations which are unambiguously artefactual.
(http://www.cs.bham.ac.uk/~whe/SETIPaper.pdf)
Some good news too - working with a few colleagues I will be using the
Arecibo dish to do some SETI as set out in that paper. We start with 5
hours in late October, and maybe some more later in the year.
Here's hoping :-)
Cheers
William
Dr. H. Paul Shuch wrote:
> Elisabeth Piotelat wrote:
>
>> 1) From a well known astronomer :
>> - Can you define what's an artificial signal?
>>
>> My answer was that we procede by elimination. We know "natural"
>> astronomical sources. We check the origin of the signal, etc, etc...
>> Do we have something else? We can say that no "non-artificial" signal
>> can use frequency or amplitude modulation.
>
>
> No, I would say that it is possible for natural phenomena to generate
> something that looks like modulation sidebands (e.g., pulsars put out
> a spectrum that resembles pulse modulation). A better indicator might
> be coherence (I know of no natural sources narrower than a couple of
> hundred kHz, while artifical sources can be arbitrarily narrow). But
> in some cases, the hallmarks of artificiality are elusive. Sometimes
> all we can say is that a given signal resembles no natural phenomenon
> which is currently known to us.
>
>
>>
>> 2) From a chemist :
>> - What do you do with the absence of result? I can't consider SETI is
>> a science if there is no way interpreting the "silence". When my
>> students can't find a molecule in an astronomical object I tell them
>> that this is a "good" result and that they have to interpret this.
>
>
> The way around this is to redefine the experiment. Instead of setting
> out to prove the existence of ETI, we should set out as our testable
> hypothesis that there are NO other civilizations out there capable of
> generating recognizable artificial ele ctromagnetic signals. That
> way, although we can never prove the negative, it takes only ONE
> counter-example to disprove it.
>
>> Someone else add that SETI is also a "social" science and that you
>> can't really compare it with what we called "hard science".
>
>
> I would be more inclined to say that SETI is an interdisciplinary
> study that includes hard science (astrophysics, planetary science,
> etc.), social science (evolution of societies), and technology (radio
> telescope design, digital signal processing, etc.) Because it is a
> hybrid, the tools of physical science, life sciences, and social
> science are all applicable.
>
>
This archive was generated by hypermail 2.1.6 : Tue Sep 28 2004 - 14:05:04 PDT