"R" == Rich  <someone@somewhere.com> writes:

R> In infinite wisdom Louis Scheffer answered:

Rich <someone@somewhere.com> writes:

How can you research something when you got zero examples to
research?

Answer: You can't.

So far so good.  So now we have two hypotheses: no examples exist,
or they exist and we have not found them yet.

R> If we've not found them yet, no examples exist. Saying that no
R> examples exist is not a statement about the existence of the sample
R> category.

Re-read what Lou wrote.  If you do not detect something, that either
means that it doesn't exist *or* that you have not yet found it.

Consider a silly example.  Do cows exist?  If I look out my window,
into my suburban neighborhood, I see no cows.  Therefore, cows do not
exist.

[...]

According to the scientific method, you have to go look.

R> Not exactly.
R> http://teacher.nsrl.rochester.edu/phy_labs/AppendixE/AppendixE.html
R> 	[...]

R> 	I. The scientific method has four steps

Well, this is the formulaic scientific method, but o.k.

R> 1. Observation and description of a phenomenon or group of
R> phenomena.

Radio transmissions from the Earth are detectable over interstellar distances.

R> 2. Formulation of an hypothesis to explain the phenomena.  [...]

Hypothesis:  There may be other civilizations in the Galaxy also capable of 
producing radio transmissions detectable over interstellar distances.

R> 3. Use of the hypothesis to predict the existence of other
R> phenomena, or to predict quantitatively the results of new
R> observations.

Observations at radio wavelengths can be conducted at a certain
sensitivity levels (call this S).  These sensitivity levels translate
to a distance for an assumed transmitter power (roughly d ~ sqrt{S/P}
for an assumed transmitter power P).  If one conducts a search at a
sensitivity level of S and finds no examples of ET broadcasts, the
number of radio transmitting ET civilizations in the Galaxy cannot be
more than roughly (D/d)^2, where D is the diameter of the Galaxy.

(One can of course do this more carefully and fill in the numbers, but
this is the general idea.)

R> 4. Performance of experimental tests of the predictions by several
R> independent experimenters and properly performed experiments.

Otherwise known as SETI.


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