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Author Topic: There's no one out there!  (Read 57870 times)

justboatonic

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Re: There's no one out there!
« Reply #200 on: January 23, 2010, 06:21:25 PM »


I understand your points to be these?

1 - the galaxy is old - there should be time for civilisations to appear
2 - the idea that humans would not recognise alien signals is flawed because aliens would use similar physical phenomena to us to communicate
3 - there are galactic limitations for habitable planets which limit their numbers
4 - dyson spheres have not been found by seti


Umm. Pause for breath...

1 - the galaxy may be old, but humanity has been searching for a very short time, and has not even looked properly yet. I submit that even in an area teeming with intelligent life, a short untutored glance may notice nothing.

2 - this seems to be a misconception of what I said. I said nothing about technology being unable to be recognised because it was alien. I said it might not be recognised because it was beyond our current technical capabilities. Clarke's third law applies, as does my 'jungle drums' illustration. A human tribe which did not understand electromagnetic wave propagation could not detect radio which other humans understand - we do not understand, and cannot detect, for example, the instantaneous transmission of data through quantum spin manipulation. In fact, since I just made that up, we have no idea whether it makes sense or not, but if it did exist it would be a far superior data transmission method for long distance use, and would be the obvious way of passing inter-system information - radio or light would be thought useless and not used at all...

3 - I know of no suggestion that there are major restrictions on human-habitable areas of the local galaxy. Obviously places where there are strong radiant clusters would be unsuitable - the galactic centre, for instance, but most of the areas in the arms would be fine. Our system is primarily influenced by the heliosphere; the sun is the main driver for habitability. Of course, if there were such galactic limitations, that would go some way towards explaining why we have found little evidence of alien intelligence so far...

4 - This is an odd point to make. Seti is not looking for phenomena associated with dyson spheres, so of course it would never see any. In fact, I can only think of one project which has done any work on looking for these - the 2004  Fermilab IRAS filter-based search - which reported in 2009 that it had found a few candidates but remarked that it was hard to distinguish between natural and artificial shading. The general feeling seems to be that we are right at the start of this kind of investigation, so it is odd for you to say "We have had the technology to search the sky for dyson sphere constructs for at least 100 years" (which I think is an exaggeration - CCDs have been around for less than 30 years). This statement suggest that we have been looking for 100 years, which is certainly not true.

Given the small amount of work that has been done on Dysons, I am surprised that you claim that "The rotation and orbit of the earth around the Sun means all the sky is covered and the supposed lack of suitable telescopes in the southern hemisphere doesnt really hold up to scrutiny.". Any individual telescope can only see a maximum of 1/2 of the sky (more like 1/3 when horizon limitations are taken into account). The earth's rotation and orbit are essentially in the same plane, so northern telescopes cannot ever see southern star systems. And the Arecibo telescope that SETI uses is fixed, and can only scan a 40-degree band of the sky anyway.

As well as these limitations, few telescopes are ever tasked to search for 'extraterrestrial intelligence'. They are too busy with basic research. We may have had the technology to look for a fair time, but the actual history of SETI investigations is best described as 'symbolic', and certainly not comprehensive. Occasionally small projects to examine a restricted set of stars at one radio wavelength have been undertaken - it is unsurprising that these have found little. We are only just now moving into an age of readily-availible computing power which would make large-scale studies practical. Which takes me back to my original point - the most obvious reason for not finding anything is that we have not seriously looked so far....


Oh, and a point for those who see other animals as a 'different' form of life. As far as we can tell, there is only one form of life on this planet (though research in deep sea trenches might throw up something unusual). It's protoplasmic, protein-based and uses DNA to  store, transmit, and duplicate genetic information. (let us leave RNA and viruses for another thread). Sometimes this life exists as a single cell, sometimes cells come together to form a symbiotic relationship. This can result in strange shapes. But they're all the same single lifeform.


Point 1, the galaxy is old. Latest findings put it at over 13 billion years. You use the premise that since we have not been looking for long, this means we have less chance of findin them. But Fermi's Paradox is that if the galaxy is teeming with intelligent civilisations, they should be easily spotted by use because of colonisation, their artefacts and super sized constructs such as dyson spheres and their variants etc etc.

In a very old galaxy teeming with intelligent life, ie it is plentiful, 40 years of looking should be rather irrelevant. In fact, when Fermi first proposed his paradox, the 'space age' had barely started if at all. Fermi's Paradox is based on the fact that with plentiful intelligence, it should easily be spotted. It is not. It can be concluded therefore that the galaxy isnt teeming with intelligent life. If it is not teeming with intelligent life, it must by definition be quite rare.

Point 2, again in a galaxy teeming with intelligent civilisations, it is very unlikely that all of these civilisations are using a communications medium we do not know off or understand. Some may be using communication mediums we do not understand or have but it would not be the case that they all have this special medium or even a majority of them would have it. Ergo many would be using radio \ elctromagnetic or light \ lasers.

Of course if the galaxy is not teeming with intelligent civilisations as per Fermi's Paradox, then it is quite possible that the one or two intelligences that exist may have this unknown communications medium and therefore they and us would never be able to communicate. But then again, this would go a long way to proving Fermi's Paradox.
I would point out that the proposition I mentioned regarding aliens being so alien each would not recognise the other was in answer to a general comment by others who support that proposition.

Point 3. The Rare Earth Hypothesis would give you more information. I'd also suggest having a magnetar, nutron star or super nova within a 1000 LY's could make your region of space in the galaxy a rather unsavioury place to be.

Point 4, I have never suggestted SETI is looking for Dyson Spheres. I have said Dyson himself stated such a construct around a star would make it ideal to search for and be a sign of an intelligent civilisation. There are others who are looking beside SETI o signs for intelligent civilisations. Amongst their means are searching for these civilisation's arefacts. These arefacts include von Neuman and Bracewell probes and Dyson Spheres and their variants. It was Dyson who suggested searching for such constructs many years ago and he didnt seem to think it was beyond our technology now so Im surprised you claim the technology isnt there. Dyson proposed in 1959 such constructs could be detected in the infra red. Spectral analysis of light by using telescopes could also be used. Telescopes have been available for far more than a hundred years so it isnt beyond realism that even quite straightforward observations of the galaxy would not reveal such items.

I'd also point out that while FERMILAB may state it has a couple of candidates, SETI said the same thing about Wow! and SHGb02+14a so nothing new there.

You are correct regarding the amount of sky an individual telescope can see however, we arent talking about individual telescopes. We are talking telescopes all over the globe. Even if we were not specifically looking for such constructs as a Dyson Sphere or its variation, the infra red signature of such would literally stand out like a beacon. In the observable light range, given the size of such a construct, this should also be noticable to the observer if any existed.

Once again, perhaps not unnaturally, the subject is turned to one of 'we havent been looking long enough.' However, this ignores a fundemental of Fermi's Paradox. If the galaxy has ever been or is teeming with intelligent civilisations, we should not have to look very hard or very long because the galaxy would be so populous, we should be falling over them.

Fermi's Paradox cannot simply be dismissed because we havent looked long enough since in a galaxy teeming with intelligent civilisations, they would not be difficult to find.
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dodgy geezer

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Re: There's no one out there!
« Reply #201 on: January 23, 2010, 06:48:20 PM »


DG, I think you borrowed your "Quantum Spin" without acknowlegements - Paul Dirac I think....


Made it up on the spur of the moment, and it is intentionally imprecise - I was going to propose a way of extracting data from quantum froth, but then I thought people might think that was something to do with beer... I was probably thinking of Blish's instant communicator mentioned in his 'Beep' story which, as you rightly point out, is named after Dirac...

(Actually, quantum crypto DOES depend on detecting spin states of entangled particles when the waveform of one has collapsed, so we are at the edge of using this technology - but don't tell anybody! We certainly have no way of determining if anyone else is using this sort of technology to communicate...)
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dodgy geezer

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Re: There's no one out there!
« Reply #202 on: January 23, 2010, 09:15:31 PM »

. But Fermi's Paradox is that if the galaxy is teeming with intelligent civilisations, they should be easily spotted... Fermi's Paradox is based on the fact that with plentiful intelligence, it should easily be spotted. It is not. It can be concluded therefore that the galaxy isnt teeming with intelligent life. If it is not teeming with intelligent life, it must by definition be quite rare.

Fermi's paradox actually refers to aliens making themselves known to us. 'Why aren't they here?' he asked. What you are actually talking about is sometimes called 'The Great Silence' - 'Why can't we see or hear them?'. And I really have to repeat - we have barely begun to look. Only if you think that 'teeming with life' means that sometimes you can't see the Sun because of flying saucers would you think that a casual glance would be sufficient. Most of space is, and always will remain, a very empty place. You really do have to look for things in space, and that means getting a grant or some other funding. There has been a lot written about looking for alien intelligence, but really remarkably little work actually done. I have seen assertions that "We have had radio telescopes since the 1930s - why haven't we found aliens?" - as if the only thing that radio astronomers do is look for evidence. In fact, evidence might well have been found and not published, on the grounds that it didn't match the natural phenomena which the scientists were studying, or it might well be in data but not uncovered. See my last point here for an illustration of the difficulties of looking for objects in space....


Point 2, again in a galaxy teeming with intelligent civilisations, it is very unlikely that all of these civilisations are using a communications medium we do not know off or understand.

Light or radio is a slow medium, even for planetary distances. We ourselves are now cutting back on our wide use of it, so it is quite likely that by the time any civilisation expands beyond their own planet they have already developed something better. But again, we are not in a position to say that we have looked everywhere....


Point 3. The Rare Earth Hypothesis would give you more information. I'd also suggest having a magnetar, nutron star or super nova within a 1000 LY's could make your region of space in the galaxy a rather unsavioury place to be.


More like 100 LY I would say, and with a galaxy around 100k LY across and 1k LY thick, that still allows a good space. But this is not really an issue...


... It was Dyson who suggested searching for such constructs many years ago and he didnt seem to think it was beyond our technology now so Im surprised you claim the technology isnt there.

 I'm NOT claiming it's not there. I'm pointing out that it's not USED for this purpose. Your implication seems to be that if I look through a scope I might by chance see something that I recognise as alien. That's not how observing works. Observing is gathering data for a pre-defined purpose. Only if I go looking for aliens will I get any data that might answer the question, and it's vanishingly rare for a professional to be funded to do this.


Dyson proposed in 1959 such constructs could be detected in the infra red. Spectral analysis of light by using telescopes could also be used. Telescopes have been available for far more than a hundred years so it isnt beyond realism that even quite straightforward observations of the galaxy would not reveal such items.... Even if we were not specifically looking for such constructs as a Dyson Sphere or its variation, the infra red signature of such would literally stand out like a beacon.

Here is a link to a Fermilab page which points out some of the technical difficulties of finding a Dyson signature. Note that this:

- is a work in progress, this project has only just started
- indicates that nothing will 'stand out like a beacon'; you have to do a lot of filtering work on specifically-gathered data just to come up with possible candidates. This costs money and time, so it is never done unless you are funded to look for these things. You certainly don't just 'see them' while looking at galaxies...

http://home.fnal.gov/~carrigan/infrared_astronomy/Dyson_sphere_look_alikes.htm
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Wasyl

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Re: There's no one out there!
« Reply #203 on: January 23, 2010, 09:38:02 PM »

Why do you all torture yourselves so,...why can,t you just accept,..that, your born, you live,then you,die,...and those that have been good,will go to heaven and sit on high,...whilst, those that have been bad, will go down below,and become one of Old Nicks,coal shovellers, %%

Wullie,...who might end up a coal shoveller {-)
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justboatonic

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Re: There's no one out there!
« Reply #204 on: January 23, 2010, 10:41:21 PM »

Im sorry but someone is getting seriously mixed up with FP and the Great Silence.

Fermi's Paradox does not refer to aliens making themselves known to us. The paradox is the apparent contradiction between the supposed high estimates of the probability of extraterrestrial civilizations existing in the galaxy and the lack of evidence for, or contact with, such civilizations. In effect, where is the evidence to support the existence of a galaxy teeming with life.

The 'great silence' is closely related but not the same.
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Colin Bishop

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Re: There's no one out there!
« Reply #205 on: January 23, 2010, 11:14:37 PM »

Well, it's been a very interesting discussion but it seems to me that the arguments are now being repeated to no useful effect. People have their views but there is no way of arriving at a definitive conclusion - not in the next half a million years or so anyway.

The only provable fact seems to be that Wasyl is broadcasting on all available wavelengths but the message is undecipherable.  :}

Colin
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justboatonic

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Re: There's no one out there!
« Reply #206 on: January 23, 2010, 11:25:17 PM »

Well, it's been a very interesting discussion but it seems to me that the arguments are now being repeated to no useful effect. People have their views but there is no way of arriving at a definitive conclusion - not in the next half a million years or so anyway.

The only provable fact seems to be that Wasyl is broadcasting on all available wavelengths but the message is undecipherable.  :}

Colin

Nanoo - Nanoo!  :-))
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dodgy geezer

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Re: There's no one out there!
« Reply #207 on: January 23, 2010, 11:39:32 PM »

Im sorry but someone is getting seriously mixed up with FP and the Great Silence.
Fermi's Paradox does not refer to aliens making themselves known to us.

As I recall, his quote was "If they existed, they should be here by now" - in other words, 'Where are the spaceships?'.  But the only point  I wanted to make was that I was talking about the technical issues of us detecting alien civilisations with our current capabilities, rather than the associated one of 'Why aren't there any aliens here?' (to which one of the answers is, of course, that they already are, and are running model boat forums...).


 
Wullie,...who might end up a coal shoveller {-)

Coal Shoveller? Luxury! We used to dreeemm o' coal shovelling when I were a lad...

Well, it's been a very interesting discussion....

Glad you like it - we try to give satisfaction....
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justboatonic

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Re: There's no one out there!
« Reply #208 on: January 24, 2010, 01:59:54 PM »

As I recall, his quote was "If they existed, they should be here by now" - in other words, 'Where are the spaceships?'.  But the only point  I wanted to make was that I was talking about the technical issues of us detecting alien civilisations with our current capabilities, rather than the associated one of 'Why aren't there any aliens here?' (to which one of the answers is, of course, that they already are, and are running model boat forums...).


 
Coal Shoveller? Luxury! We used to dreeemm o' coal shovelling when I were a lad...

Glad you like it - we try to give satisfaction....

Im certain Fermi's exact quotes are not recorded anywhere as it was over lunch at Los Alomos the paradox was postulated, informally by Fermi. What is not in dispute by those who were present ie Emil Konopinski, Herbert York and Edward Teller, is that Fermi postulated in a galaxy which is supposed to have abundant intelligent civilisations ie not a few, that we should easily be able to detect these civilisation.

In other words, the 'we havent been looking long enough' argument isnt valid since 'many' would easily be apparent. Which in essence, is where the thread all started!
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dodgy geezer

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Re: There's no one out there!
« Reply #209 on: January 24, 2010, 03:44:57 PM »

Im certain Fermi's exact quotes are not recorded anywhere as it was over lunch at Los Alomos the paradox was postulated, informally by Fermi...

Here is a link to the recollections of those who were there:

http://www.fas.org/sgp/othergov/doe/lanl/la-10311-ms.pdf

You will see that Fermi's comments were essentially 'Don't you wonder where everybody is?', which I read to mean 'Why don't we bump into aliens in the course of our regular affairs?', while the assertion that we can't find them when we look is a subtly different later development of the question, pushed by Michael Hart amongst others.

I am responding to the second of these questions, not the first. Everybody agrees that alien species are not immediately and obviously present to earth dwellers, and one answer to this is certainly that they do not exist. Questions of this type will invariably start raising issues like the Zoo hypothesis, and I am not an expert on extraterrestrial psychology and sociology... But I do know something about astronomical techniques, enough to know that there really have been very few attempts to make any kind of search, and that in astronomy, if you do not plan a specific search, you do not find anything.

We may certainly search in the future and find nothing. But I do not think that you can take the fact that telescopes have existed for many years to mean that we have been searching for that long and have not found anything.

Probably the only search we have undertaken which was not a symbolic gesture is SETI. This has been going since 1999 - the SETI chief astronomer says that, based on his estimate of the Drake equation, he expects to get a single hit sometime before 2025. And SETI has now lost its government funding, and still has no southern hemisphere feed. If he thinks we haven't been looking long enough or hard enough, I'm not going to disagree....
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BrianCartwright

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Re: There's no one out there!
« Reply #210 on: January 24, 2010, 04:05:27 PM »

A very interesting discussion.Er...I'll get my coat.
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Bryan Young

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Re: There's no one out there!
« Reply #211 on: January 24, 2010, 07:01:00 PM »

For all those following this thread I suggest that Page 13 of todays Sunday Times is required reading. BY.
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Colin Bishop

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Re: There's no one out there!
« Reply #212 on: January 24, 2010, 07:25:15 PM »

Topical Bryan, but it doesn't go into the depth of argument we've seen on here.

Colin
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Jimmy James

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Re: There's no one out there!
« Reply #213 on: January 24, 2010, 09:38:48 PM »

Using the princable of Occam's Razor  -----  {:-{----- Maybe there are Thousands or Millions of advanced Civilisations in this Galaxy But no one has developed a faster than Light or Warp Drive, so--- they are restricted to their own solar systems ---- Maybe FTL drive is not possible or maybe it is not possible for a living being to travel FTL !!!!! This could maybe explain why we haven't had the Nabors knocking on the door asking if they can borrow a bowl of sugar...As for communications using radio waves to reach the nearest solar system is like going out into your front garden and shouting to a friend who lives a mile away (The chances of him hearing it are astronomic and even if he did hear it it would be so distorted by background noise he wouldn't recognise what it was anyway   :(( :((
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dodgy geezer

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Re: There's no one out there!
« Reply #214 on: January 24, 2010, 10:25:37 PM »

Topical Bryan, but it doesn't go into the depth of argument we've seen on here.

Colin

Oh.   If you want depth of argument, I'll get the wife...

I'm intrigued - what does p13 of the Sunday Times say?


William of Occam suggested that you should not multiply suppositions unnecessarily - in other words, you should pick the simplest answer that fits the facts. And I am bound to say that the simplest conjecture is indeed that intelligent aliens do not exist. Note that I was not arguing that they do exist - I was arguing that not finding Earth-like planets or, indeed, radio signals should not be taken as suggesting that they do not exist, because we have done so little looking of any kind which might find them. We have talked about it a lot, but we have rarely got any funds to do anything....

If anyone is actually still wondering if alien intelligence exists a most useful insight was provided by dreadnought72 a little earlier. He said:

I'm not so sure.

From the top: intelligence/sentience isn't a "natural" outcome of evolution. It happened for us, but it didn't happen during the previous 100 million years of mammalian existence. Indeed, it needn't have happened at all. It's not a "given" for evolution....


It is instructive to consider that, as far as we can tell, life seemed to start on Earth almost the minute it cooled down sufficiently to have liquid water - at about 0.7bn years after the formation. We have had nearly 4bn years of life - most of that would be single-celled animals, but we have had about 0.5bn years of complex animals. Reptiles have been around for 0.3bn years, mammals for 0.2bn years. And yet, as far as we know, none of these developed intelligence. The earliest hominids are about 4m years old, but they have displayed our type of manipulative intelligence for only about 2m years.

Applying the simplest inference to this data suggests that life will emerge rapidly if the conditions are suitable but that intelligence is quite rare. Of course there is another possibility - that occasionally reptiles and other complex animals did develop intelligence, but that intelligence has no survival value, and the creatures that develop it rapidly doom themselves as a species.... perhaps by arguing on model boat forums when they should be doing something else....
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Colin Bishop

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Re: There's no one out there!
« Reply #215 on: January 24, 2010, 10:32:31 PM »

Quote
I'm intrigued - what does p13 of the Sunday Times say?

Approximately what you two have been saying but in about 1/100th the space.  :}

Colin
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Colin Bishop

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Re: There's no one out there!
« Reply #216 on: January 25, 2010, 09:42:43 AM »

And here's the definitive answer: http://news.bbc.co.uk/1/hi/sci/tech/8478033.stm

On BBC Breakfast they were explaining this to the audience - "The Sun is a star and has nine planets.....". Really deep intellectually challenging stuff. No doubt they think that a Dyson Sphere is that ball thing on the front of the new vacuum cleaners.....

Colin
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dodgy geezer

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Re: There's no one out there!
« Reply #217 on: January 25, 2010, 10:32:30 AM »

And here's the definitive answer: http://news.bbc.co.uk/1/hi/sci/tech/8478033.stm

On BBC Breakfast they were explaining this to the audience - "The Sun is a star and has nine planets.....".


Umm.  In fact, to quote Frankie Howard, 'Umm, Umm and thrice Umm...'.

I might be gratified to have Lord Rees supporting my contention that the chance of detection of alien life is not looking poor at the moment, if I had any confidence in him as a scientist. Unfortunately, I don't.

I like your BBC reference, and am impressed with journalists who can print a story like that a few months after they have printed a story like this:   

http://news.bbc.co.uk/1/hi/england/norfolk/7352181.stm

I presume they have no short-term memory, and think their viewers don't either? Unfortunately, they may well be right. Did they really say 'nine planets'? Still, look on the bright side - the BBC coverage of Global Warming is scoring really well in the comedy section....


 




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justboatonic

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Re: There's no one out there!
« Reply #218 on: January 25, 2010, 12:24:11 PM »

And here's the definitive answer: http://news.bbc.co.uk/1/hi/sci/tech/8478033.stm

On BBC Breakfast they were explaining this to the audience - "The Sun is a star and has nine planets.....". Really deep intellectually challenging stuff. No doubt they think that a Dyson Sphere is that ball thing on the front of the new vacuum cleaners.....

Colin

Clearly he's forgotten Pluto is now no longer a planet and is in a sub class called dwarf planets.

However this from the telegraph gives a clue that the scientific community may be losing faith with SETI http://www.telegraph.co.uk/science/space/7068765/The-search-for-aliens-should-start-on-Earth-not-outer-space-says-scientist.html

"Prof Davies said: We need to give up the notion that ET is sending us some sort of customised message and take a new approach."

I should also point out that searching for extraterrestrial civilisations didnt start in 1999. It has been ongoing for nearly 50 years now. Although the SETI organisation as such is much younger, examples such as WOW! confirm the search was existing well before that time. SETI is effectively, a collective name for a number of searches over a long period of time.

The SETI League was formed in 1994 comprised 1500 members in 62 countries. SETI is now the generic name for the search for other intelligent civilisations.
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dodgy geezer

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Re: There's no one out there!
« Reply #219 on: January 25, 2010, 01:17:14 PM »

.. this from the telegraph gives a clue that the scientific community may be losing faith with SETI http://www.telegraph.co.uk/science/space/7068765/The-search-for-aliens-should-start-on-Earth-not-outer-space-says-scientist.html
"Prof Davies said: We need to give up the notion that ET is sending us some sort of customised message and take a new approach."

Possibly a tad exaggerated - this looks more like Prof Davies researching a new area to extract grants from? I note that Colin Pillinger (he of the Beagle II) replied:

"I prefer to deal in scientific fact - this is wildly science fiction. You'd be off your trolley to go searching for arsenic-based life."

Though I disagree with that statement as well - Prof Pillinger argues that Mars is the most likely place to find alien life, so he is interested in keeping a space grant alive...

Isn't politics wonderful?

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justboatonic

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Re: There's no one out there!
« Reply #220 on: January 25, 2010, 06:21:26 PM »

It has been suggested that SETI may be only effectively searching half the galaxy since the southern hemisphere has few or no telescopes to perform this function.

While SETI searching for a candidate signal has been ongoing for nearly 50 years, its never been put out there before that due to a lack of southern hemisphere telescopes has this impinged in any way SETI's search to a greater or lesser degree. And neither should it.

We only have to consider the dynamics of the Earth, Solar System and Galaxy to see a suggestion that the southern hemisphere is not able to contribute fully to the search is, in short folly.

Take for example the Earth. The Earth's axis is tilted at approximately 23 degrees. Tilt any sphere as an angle equal to this and rotate it. You'll immediately be aware that although the lower half or southern hemisphere does indeed look downwards, it only does this for half a rotation. The other half of the rotation the lower half or southern hemisphere is indeed pointing upwards! Conversely, this means the upper half or northern hemisphere is looking downwards for half a rotation. Ergo, it can easily be seen that even if the southern hemisphere does not have sufficient telescopes to search for a signal, those in the horthern hemisphere will be able to scan the southern sky at least once in a full rotation of the Earth.

But that's not all. The Earth orbits around the Sun. In a full year its easy to see that tilt of the Earth will allow the northern hemisphere where most of SETI's telescopes would be suituated to see virtually all of the galaxy some may argue could only be covered by southern hemisphere based telescopes.

The Solar System is also not moving within the galaxy in just one plane. The Solar System moves up and down relative to the galactic plane although this movement is small within our timeframe.
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justboatonic

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Re: There's no one out there!
« Reply #221 on: January 25, 2010, 07:30:43 PM »

If they are out there, they are probably like us http://www.telegraph.co.uk/science/science-news/7071013/Aliens-are-likely-to-look-and-behave-like-us.html

Perhaps more interestingly he also thinks "that because much of the Universe is older than us they would have evolved further down the line and we should have heard from them by now.

He believes it is increasingly looking like they may not be out there at all.

"It is about time they turned up," he said. "It is very, very quiet out there. Suspiciously quiet. Where on Earth are they? I personally don't think that there is anything out there."

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dodgy geezer

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Re: There's no one out there!
« Reply #222 on: January 25, 2010, 09:03:08 PM »

It has been suggested that SETI may be only effectively searching half the galaxy since the southern hemisphere has few or no telescopes to perform this function.

While SETI searching for a candidate signal has been ongoing for nearly 50 years, its never been put out there before that due to a lack of southern hemisphere telescopes has this impinged in any way SETI's search to a greater or lesser degree. And neither should it.

We only have to consider the dynamics of the Earth, Solar System and Galaxy to see a suggestion that the southern hemisphere is not able to contribute fully to the search is, in short folly.


A large number of Ums!


I do not understand the claim that SETI has been looking for 50 years. As I said earlier, SETI programs have been episodic and symbolic. The only continuous program I know or is the Seti@Home project based at Ariceibo. I shall refer to this as SETI when writing below.

SETI started in 1999. I joined it in 2000 and have been running a SETI processing farm of 20 machines in my attic until quite recently, getting into the top 100 unit processers in the UK. There were very few of us processing in the early years, and a major software upgrade from 'Seti Classic' in 2005 really means the SETI you know has been operating for around 5 years. My wife complains about the power drain - she would complain a lot more if I had been doing this for 50 years!


I query the geometry of your next point, and think you may be confused by the seasons, or perhaps you think that the Earth varies its obliquity during its rotation in some way. It is true that the earth has an axial tilt of some 23.5 deg compared to the ecliptic, but this tilt is constant (ignoring nutation). Ignore the rest of the solar system and consider the earth as a globe - it spins continually on a single axis and people in the northern hemisphere only get to see the Northern sky. That 'northern sky' is slightly different to the northern sky you would see if the planet had a tilt of 0 deg with respect to the plane of the ecliptic, but it is still only 180 deg.

You do get your 23.5 deg swing as the earth goes round the sun, but only with respect to the sun and the planets, which are in the ecliptic. This is what gives us our seasons, and the planets' rise and fall. The only way to see different fixed stars is to travel to the south - that is, indeed, why they are called 'fixed'. There are various Milankovitch cycles which will alter viewing somewhat, but we can discount those for our lifetimes, since they are many thousands of years long...


So for any one spot on the earth you have a theoretical 180 deg view of a static sky with a MOUNTED telescope. In fact, given horizon effects, you would be lucky to get more than 120 even in ideal conditions. However,I am sure you realise that Ariceibo is a FIXED telescope, built into a dip between hills. You can vary the viewing angle somewhat by varying the receiver position - a cone of 40 deg max is possible. That is actually less that 1/2 - more like 1/3 of the sky - the maths is here: http://safalra.com/science/astronomy/setis-sky/

As well as this limitation SETI is not a paying user of the telescope, so it cannot determine where it is pointed. It piggy-backs other work, so it only looks where they look. This, of course, limits viewing even further. On top of that, SETI can only operate at night, when the sun does not interfere with the frequencies on which it listens. 

So in total, the amount of sky visible to SETI is very limited. They had been looking for a southern hemisphere site before their funding was cut, but they won't get one now. Project ARGUS is an attempt to get amateur watchers to organise for a seti-type study, and I understand that a telescope in Argentina has some funding for a project, but I do not follow what they are doing in detail.

I hope my explanation makes sense - it's a bit of a brain-dump. I'm sure that someone on Mayhem understands enough about celestial navigation to provide a better one...?
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dodgy geezer

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Re: There's no one out there!
« Reply #223 on: January 25, 2010, 09:22:17 PM »

If they are out there, they are probably like us http://www.telegraph.co.uk/science/science-news/7071013/Aliens-are-likely-to-look-and-behave-like-us.html

Perhaps more interestingly he also thinks "that because much of the Universe is older than us they would have evolved further down the line and we should have heard from them by now.


Most interestingly to me he also seems to think that:

They could come in peace but also be searching for somewhere to live, and to help themselves to water, minerals and fuel...

Europa has twice the liquid volume of water of all the Earth's oceans. Titan is full of methane, and the asteroids have all the minerals you could wish for. And none of these places has a gravity well anything like the Earth's, being about 0.15 G.

So either we have a professor who knows little about the distribution of raw materials in the Solar System, or a professor who is inclined, for some reason, to present a Hollywood view of the subject. In either case, I am disinclined to accept his reported opinions without further information...

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justboatonic

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Re: There's no one out there!
« Reply #224 on: January 25, 2010, 10:20:59 PM »

Most interestingly to me he also seems to think that:

They could come in peace but also be searching for somewhere to live, and to help themselves to water, minerals and fuel...

Europa has twice the liquid volume of water of all the Earth's oceans. Titan is full of methane, and the asteroids have all the minerals you could wish for. And none of these places has a gravity well anything like the Earth's, being about 0.15 G.

So either we have a professor who knows little about the distribution of raw materials in the Solar System, or a professor who is inclined, for some reason, to present a Hollywood view of the subject. In either case, I am disinclined to accept his reported opinions without further information...



Not necessarily and I think thats a little disingenuous.

If we consider for a moment that these aliens come from a planet in the habitable zone of their star, it is not beyond reason that their eco system could be similar to ours ie liquid water and a temperate habitat. While it is undeniable the riches that abound in the outer solar system the logistics of getting those could be difficult even for a species that has travelled the stars. Far easier to get these from Earth where the conditions for their life may be closer to those as their home world. In such circumstances, it would not be beyond reason they would take the easy option and take what was required from Earth first before moving on to harsher environments. Pretty much as we have done in the search for oil. First we searched for and extracted that which was easy to get to. Now we are having to go to harsher places on Earth to extract it.

Of course there could be other more sinister reasons to visit Earth instead. 6 billion (human) lifeforms could be an idea food source or workforce. Sure Hollywood may have thought that but that's no reason to dismiss a non benevolent ET.
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