is repeatable and not of artificial origin

There is the possible cause for our current failure to detect. --I am referring to the word "repeatable".
Any contact is most likely to be a one-time focused beam that is randomly fired at positions in the sky.

Our own message was a one-time affair.

The repeatable nonsense implies eavesdropping on a nearby civilization. 50 years, very few stars within 100 to 1000 light years no truly habitable planets yet found anywhere should put the lie to eavesdropping on the "Billions of Civilizations of which the Galaxy is teeming"

If we get and record a true 'we are here' type of contact--it will likely be from thousands of light years away and will simply and wonderfully confirm that we are not alone in the Cosmos as sentient and highly intelligent beings.

There are only 512 known stars within 100 light years of earth, which basically was my original point made here which was that, space is a damn sight bigger than people realise, so no I don't believe that the universe is teeming with life.

Yes.
Only 512 G-type main-sequence stars like our sun within 100 light years...
There are probably many more stars of other types like yellow dwarfs, orange dwarfs, red dwarfs, and white dwarfs,
But that those stars should have planets with life are considered unlikely.
But I have read that the SETI Institute tries to detect radio signals even 1400 light-years away.
https://www.seti.org/seti-institute/mysterious-star-kic-8462852
So perhaps its about 14 times more stars to listen to.
Still that is a very small fraction of the Milky way.

Btw. Our space is very empty. And contains only about 2 atoms per cubic meter on average.

I think the likelihood that we will detect a communication signal directed at us from an inhabited planet or a relay sitting in interplanetary space is not high on the probability scale. I remember though when I first saw the Drake equation the estimated percentage of stars with planets was well below 10%. That figure, according to the scientists who discuss these things on television programming regarding ET is now estimated to be much higher. Even so, space is a mighty big place, quoting Jodie Foster in "Contact". If contact does happen while I'm still alive I will die a happier man, but by now after 20 years of seti@home I have my doubts about whether that event will occur while I'm around to appreciate it. I saw reference to another type of possibility which would indicate the presence of ET and that would be detecting the exhaust plume of ET's space vehicle. Of course, it is impossible to say in advance how far out the drive exhaust of a space vehicle can or could be detected.

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Bob DeWoody

My motto: Never do today what you can put off until tomorrow as it may not be required. This no longer applies in light of current events.

Hmm... The Drake equation is useless.
N = the number of civilizations in our galaxy with which communication might be possible when these terms are multiplicated:
R∗ = the average rate of star formation in our galaxy
fp = the fraction of those stars that have planets
ne = the average number of planets that can potentially support life per star that has planets
fl = the fraction of planets that could support life that actually develop life at some point
fi = the fraction of planets with life that actually go on to develop intelligent life (civilizations)
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L = the length of time for which such civilizations release detectable signals into space

Well, R∗, fp and ne are terms that scientists perhaps now have a rough idea what it could be.
The other terms are totally unknown.
So far we only know for fact is that N = 1, or perhaps N >= 1.

The only difference between this and this is the titles as both require contact.

Well the Institute of Physics disagrees with you and so do I.

Your exception has been noted.

If we were spotted, then the hello signal might very well be repeated until we pull our head out and decode it. I am thinking right now that we have spotted no one and I presume they haven't spotted us. I do think that we should send our own Hello message to nearby stars--it doesn't have to be only once.

I fancy that a true contact might just be a beacon that slews its message around to all directions and may not be repeated in our direction if it is truly narrow band.

I was also referring to the almost 500KW signal that we blasted toward a far-away galaxy from Arecibo some years back. it was not repeated to the best of my knowledge

so at the base, that Drake equation is wrong.

I prefer the Rothamel Equation:

(% of stars that are main sequence) x (% of those with planets in a temperate zone) x (%of those planets that have near circular orbits) x (% having an atmosphere containing O-2) x (%that have a magnetic field) x (% that have abundant water and dry land) x (% of those having a stabilizing moon) x (% that have gravity within a narrow range) x (% of those that have an Ozone layer) x all of the other requirements for intelligent life similar to ours to start and evolve.

Right now I abhor the uncertainty of all of these factors--none-the-less--it's not looking good for billions of civilizations in the Galaxy. Stick your numbers or guesses in my equation above--if you come up with, say, 1 in ten million then you are too optimistic in your estimates. I, myself, will go with my gut feeling of maybe 5 civilizations in the Galaxy-possibly 30,000 light years between them or more.
not ashamed to be ignorant but worry that we won't answer these questions with any more precision any time soon.

Rebuttals welcome !!

Addendum.

x (% of those that have a large gas giant outbound to absorb collisions) x (% of those those that have an axis tilt to provide seasons) x (% of those that have been planets for a few million years). Without adding any other conditions which may be necessary (such as notions of "contemporaneous" existence time lines--adjusted for distance ) you should be estimating about 4 in a billion or so. I still will stick with my 5 civilizations in the Galaxy which I claim is no more uncertain than any other estimate.

i think there are some "levels" or "items" are there only for trying to reduce the numbers.

let those exo-biologists who are far more qualified and better paid than I step forward and say which of my conditions are unnecessary or redundant and also let them add the ones I missed possibly relating to amino acids and maybe trans-spermia. Perhaps there is intelligent life on a level with humans in the oceans of moons that are heated by gravitational squeezing or vulcanism who somehow can communicate under water and across the cosmos.

correction; A few Billion years aging on a planet i.e. 10^9 for you all across the pond

correction; A few Billion years aging on a planet i.e. 10^9 for you all across the pond

in fact.... you can skip the stars equation and jump right away to the number of planets in godilock zones
https://www.nasa.gov/feature/ames/kepler/moreplanetsthanstars

But how many planets can a goldilock zone host?
Here both Venus and Mars failed to be host of life.

You definitely know the stuff here, Chris, and also how to write, but perhaps tell me in which way we are supposed to prove, for next only making it the Goldilocks zone.

But how many planets can a goldilock zone host?
Here both Venus and Mars failed to be host of life.

i guess 1 per star :)

We aren't donr looking on Mars and we just wrote off Venus without looking.

In order to play devil's advocate I submit the zones we are looking at are for water based life and dismiss the possibility of life based on something else.

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In order to play devil's advocate I submit the zones we are looking at are for water based life and dismiss the possibility of life based on something else.

Not quite, Some scientists have been thinking if life could also be methan based instead of water for instance. Then also some can think of silicon based chemistry instead of carbon.
A problem with those hypothesis is that chemistry gets complicated. Not like that water and carbon molecules like a DNA that mix very well together.

That is true but if so there would be a different goldilocks zone.

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Don't see # of planets nor their masses-What % of those found are in the Goldilocks zone. Remember that is one parameter out of at least a dozen which comes into play.

Whatever the mass of the star determins and it's ejector + solar/grav pull will govern
what orbit a planet will take.. Too much is based on our own system and workings

It just seems to me that we are all running around like headless chickens, no wonder we haven't found anything in nearly 20 years :-(

You made that distinctly clear on 26th March 2018. You also made it clear that you were heading for new pastures for your crunching farm to do work more worthwhile...

...hmm is it possible for you to comment without your disillusion being so obvious?

As a quick p.s. to my last message.

Ah now, my dear man. ;-) One is inclined to believe a last message from you here, sir - is unlikelier than a signal from ET.

A mention, at least, of the source from which you have quoted?