Rob Harris Cen-IT wrote:
But they are not wildly different from the truth,
> > I don't believe they can find different solutions unless they find
> > different laws of physics.
> We don't know the laws of physics. We know what we know. We have inferred
> rules from experimental data which is often unverifiable. We hope that our
> ideas are close (many are, but many still need to be tried and tested by
> implementing technologies using such science - this is particularly true of
> astrophysics - it's all theory.) but they are almost definitely not spot on.
But they are not wildly different from the truth,which is what would be required for your wild suppositions to have any merit.
> Secondly, and more importantly (this is central to my argument) you cannot
> say from what persepective an alien intelligence might view the universe. We
> look up at night and see absence of photons, speckled with photon sources,
> because we detect photons. But what about things we don't detect, things we
> have not yet discovered, or have misunderstood. These things will represent
> the differences between civilisations. For all you know the universe could
> be saturated with "slorgopo energy" which many creatures detect for some
> purpose or another, but we don't, it has no observable effect upon our
> systems and so we haven't noticed it, and evolution hasn't utilised it.
if the solar system were saturated with 'slorgopo energy' it would be reproducable in any particle accelerator on any planet in the universe, and its effects would be observable via astronomy. Photons are among the most abundant, and are the easiest to detect by any means using matter. Stars that are stable over the long term, such that they will likely be stable enough to allow intelligent life to evolve, will occupy the exact same range of the curve of stellar evolution as our own sun: it will be a yellow dwarf. It will use a carbon base chemistry (supposed silicon based chemistries give nowhere near the number of valent bonds necessary to allow information storage molecules like DNA to develop, and carbon pervades the universe). Given this, and the emission ranges of yellow dwarf stars, all aliens that see will see in a range between the near infrared to the near ultraviolet, unless their primary sensory input is from sound or smell or touch. The may have eyes like a fly, or like a reptile, or like a mammal, or something else, but chances are some animal on earth has evolved a similar mechanism, which means its likely to be in our own DNA.
> None of this means jack until we have more alien tech info (i.e more than
> none). These are issues which come into play considering exactly our human
> level of understanding and technology. They probably won't apply elsewhere
> with great frequency.
All aliens will have been primitive at some point. This is a given. Thus all aliens will have developed technologies which are useful on iron core, tectonically drive oxygen atmosphere planets circling yellow dwarf suns. Since the aliens will also know that other aliens will have gone through similar stages, they will be broacasting if they want to be heard on many different bands using many different protocols and algorithms, at the very least enough to say,"Hey buddy, change over to my main channel XXXX using YYYY tech, and heres how YYYY tech is built and works."
> > > I don't think it's likely SETI will come up trumps - even if a
> > > similarly advanced civilisation exists at the nearest star.
> > Well if they were at the nearest star there is a good chance they
> > would have been detected by now -- we have been at this for 40 years.
> Aaaaaagh! How would they have been detected? Do we have a "life-scan" that
> we can use on other planets from here? NO! This all started by my saying
> that you can't be SURE that similarly advanced alien civilisations are using
> radio - AND pointing their transmitters our way, therefore, such a
> civilisation could easily be at the nearest star, and we wouldn't know. It
> all rests on the assumption that they're ALL going to use radio and try to
> contact us, or accidentally transmit to us for some other reason - a
> ridiculous assumption IMHO.
Actually, the latest Drake Equation calculations, based on data from the Mars meteorite, our knowledge of the volution of Venus and Mars, and the possible presence of life on Europa, has resulted in a current estimate of somewhere around a 40 light year average distance between worlds, last I heard. BTW: We've been at it longer than that. The first big transmissions were early tv broadcasts in the early 1930's (which included the '36 berlin Olympics). That means we've been at it for at least 65 years, even if you ignore early radio broadcasts prior to tv. That means that if the current Drake equation calculations are accurate, and if anyone is listening, someone knows we are here.