In infinite wisdom Joseph Lazio answered:

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

[...]

R> And lots can happen in the 100,000 years it takes light to traverse
R> the galaxy, there's a bit of a lag. I suggest that the probability
R> of said civilization broadcasting in our direction is inversely
R> related to it's distance from us

That's a hypothesis.  The evidence that you have to support it is?

What? That lots can happen in 100,000 years? I think this is self
evident. FYI, I'm talking about civilizations, not stellar evolution.

As for the probability argument, seems to me that there are many
issues here, the detectability of a star (and any potential planets)
is a matter of distance. I don't expect that planets in the Andromeda
galaxy will be detected anytime soon. But even stars are not easily
detectable at great distances unless they be nova at least, and
my poor reasoning skills deduce that novas, and supernovas as well,
are not good places to look for ET. The blast aside, such stars
are generally large, live fast and die young, and don't even seem
potential candidates for life even should they have planets.

Then there are issues such as signal strength. Do you assert that
signal strength does not fall off with distance?

I really don't see what you think so contentious about this statement.
Would you search quasars for ET signals?

R> (and note that much of the galaxy is occulted and not directly
R> viewable).

This is manifestly not true.  At radio wavelengths, there is
effectively no absorption.

So?

I have observations of other galaxies seen
through the disk of the Galaxy.  Indeed, whole surveys have been
conducted in the radio to try to find background galaxies seen through
the plane of the Galaxy.

But since you can't see stars behind it, where are you going to
point your receiver to look for ET? Where are the ETI's going to
point their transmitters?

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

Otherwise known as SETI.

R> Indeed.

R> But with all the radio surveys done of the sky, with 30 years or so
R> of SETI searches of ever greater sensivity, one might question why
R> any nearby ET civilization's broadcasts have not already been
R> picked up.

Well, there are two possibilities, right?  As you note above, maybe we
haven't looked at the right frequencies or maybe there are no radio
transmitting ET civilizations nearby.

As for the issue of frequency, there seems to be some disagreement
in the views of the authority-type posters in this thread.

Dave Woolley just posted this...

---
R> to look, and you need to know what frequency at which to look.

Most searches cover a wide range of frequencies, so frequency is not
critical.

---

[...]

R> It has been claimed that a 1 watt transmitter would be sufficient
R> with modern receivers.

Umm, have you read the FAQ?

Have you read this (also from Dave Woolley)?

---

R>It has been claimed that a 1 watt transmitter would be sufficient
R> with modern receivers.

I don't know where you got that figure.  You need very approximately
1GW EIRP from the nearest star to get the S@H threshold of 22 times mean
noise power in 0.075Hz and time * bandwidth = 1.  To detect 1W EIRP at
that distance, you would need an observation time of about 1E19 seconds!
1 Watt feed point power is detectable from local stars if the transmit
aperture is similar to Arecibo, although it will require around 20
minutes observation.

---

Seems the issue of "local stars" comes up all the time.

Rich