On the subject of evidence, anybody knows what happened with that alleged signal caught coming from 47 Tucanae?
On the subject of evidence, anybody knows what happened with that alleged signal caught coming from 47 Tucanae?
*cough* 47 Tucanae *cough* .... anyone?
Posts above moved from : http://www.bautforum.com/showthread....but-not-proven.
Please don't repeat questions ("bump") just because nobody has answered according to your schedule.
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Forming opinions as we speak
i think its the australian seti laser signal right?
theres a thread on here about it... bit of a nothing story if thats what they are talking about
I'm not sure where I read it, it just clicked to me as the topic dealt with evidence (direct/indirect) of extraterrestrials in space, and I remembered reading somewhere about this signal (and another one from M67, claimed by a Ukranian astronomer), but at the time it was a fresh news, so I never looked it up to see a follow up to where the investigation has went since then.
It seems from my search that the signal was not confirmed again (I guess they thought they could catch it again, or a third time, even though everything in space moves and that is virtually impossible, unless the signal was directed). It was caught by Dr. Ragbir Bhathal from the Optical SETI Network based in Australia. It was indicated in the Astrobiology Conference Australia 2010 paper. The description is the following "In December 2008 a sharp laser look alike signal emanating from 47 Tucanae was detected."
04836.jpgBhathal's team detected an unusual strong laser signal that could not have been identified nor did it re-occur since: "It may be a glitch in our equipment, or some astrophysical phenomena (e.g an optical pulsar) or some unknown source. We are still investigating it", told Bhathal to the German online-newsmagazine "Grenzwissenschaft-aktuell.de".
Even if still unidentified, the signal's discovery seems to have created enough enthusiasm within the team to mark it with a "Was t ET?"-comment - not unlike the famous "Wow"-Mark next to the detection of a strong, narrowband radio signal detected by Dr. Jerry R. Ehman on August 15, 1977, while working on a SETI project at the Big Ear radio telescope of Ohio State University.
^ ^ ^ The signal, now dubbed "Is it ET?"
Another set of sources.
I find it curious that in one research paper, they say they had this anomalous data, indicating that 47 Tucanae could be well over 20 billion years old, which goes contrary to the standard accepted theories on the age of the universe. And considering it has metal-rich stars, it would indicate that its from a "new" enough generation.
Any thoughts guys?
47 Tucanae is a globular cluster 16700 light years away. Any light signal from that distance would not receive an answer for 33 thousand years. I think that, if they really wanted converse at that distance, they should probably have sent a slightly longer message than one lasting a few seconds.
In a conversation that consists of only a few seconds of data transmission every thirty thousand years or so, not a great deal of information is exchanged.
i forget the detail, but the good folk at seti seemed to think that you would expect to see an attention attracting simple beacon in the first instance. that dosnt mean to say they would wait for a return signal before sending a greeting, but you wouldnt necessarily expect to see them at the same time.
At that distance, if it were real it would have to be directed unless it was extremely powerful (significant compared to a star's output), but even if directed the beam spread would be considerable. Relative motion of the sun versus any possible source there would only be an issue over long periods, and if it were real, I can't imagine why someone would only send one short message.It seems from my search that the signal was not confirmed again (I guess they thought they could catch it again, or a third time, even though everything in space moves and that is virtually impossible, unless the signal was directed).
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Because it needs to be directed, you would not expect to see it continuosly - presumably ET would have many potential targets it would cycle through.
Any message would use a different method once it had got you looking in that direction...something like free electron lasers.
seth shostak has been an advocate of seti turning its attention to this kind of search for some time now.
From what i gather, the chances of ever being able to decipher a message are extremely small, possibly so low that one wouldnt be sent. The only expectation might be that you would flash back at them when you had the means.
Last edited by mutleyeng; 2012-Apr-27 at 11:20 PM.
The assumption is that they will have done their own Kepleresque searches and identified thousands of potentials.
They would have their own optical searches to see if they got a responce ...which dosnt require much energy at all.
Like i said, this is what the folk at seti think would be a likely method used by an advanced race seeking to answer the same questions we have.
There has also been folk thinking about whether we would have any chance to decipher alien messages .. unless they had some knowledge of us, then a random signal not specifically intended for us would probably be impossible to crack.
http://iopscience.iop.org website, titled as "The Spectroscopic Age of 47 Tucanae".
At first I thought maybe I misinterpreted something, as I don't always understand the technical/scientific jargon there (and I may have still, confused something about it, I'm not denying that), but this is what confused me and out of curiosity, thought I would share so somebody can explain if its what I thought it was:
"Because of its weak series of Balmer lines relative to model spectra, our results imply a spectroscopic age of 47 Tuc well in excess of 20 Gyr, which is at odds with the color-magnitude diagram age of 14 ± 1 Gyr. The derived metal abundance, however, is consistent with the known value. Although the observational constraints are restrictive, existing data cannot entirely exclude emission "fill-in" of the Hγ line as the source of the discrepancy."
I'm interested what the last sentence means?
Then again, this could very well be what the team also suspected - an optical pulsar, was something they said I believe. Or some other cosmic phenomena, we are yet to define, that doesn't have to mean - extraterrestrials.
I guess the scientific community has this fear of confirming anything, then later be proven wrong (damaging credibility etc.).
I agree though, that we would not be able to be hit with it continuously, as I also think that there would be better targets closer by then our star system. It would suck if in 16.700 light years radius, we are the only other form of intelligent life (assuming this is indeed from an extraterrestrial origin, it could very well be something else).
But I seriously doubt the other explanation, that it could be an equipment malfunction.
This is why I think astronomy news should be only reported by astronomers, not anyone else.
Thanks for the comments guys. I just thought that even if this is not an extraterrestrial signal case, that it may spark some discussion, and ponder on the ideas of what an actual event like this might bring to the table, purely on speculative means, from the detection, the place of detection, form of the signal, the deciphering, the contents, the public reaction, aftermath etc.
If they really are in 47 Tucanae then they would need to wait a very long time for an answer; but perhaps they have a different subjective experience of time to humans, in which case they probably don't have much in common with us at all.The assumption is that they will have done their own Kepleresque searches and identified thousands of potentials.
They would have their own optical searches to see if they got a response ...which doesn't require much energy at all.
On the other hand they might experience time just like we do- in which case these interstellar pings will almost certainly be forgotten in 33 thousand years time. we have, for our part, almost completely forgotten about the Arecibo Message, sent in 1974 to a different globular cluster but one which is very much like 47 Tucanae in most characteristics;
On the gripping hand the ping might have come from another star near 47 Tuc in the sky, but much closer to Earth (maybe Zeta Tucanae, for example) - in which case the transmission wasn't much good as a directional beacon, really...
whats 33k to a civilisation that may have been around for millions.
Optical beacons dont need much energy... once you are a space going civilisation you can just let the experiment run with very little cost to the society. The same cannot be said for sending radio waves that can be detectable hundreds of light years away.
The other advantage is that the ability to send and recieve such greetings would be available to civilisations in their very early stages of technological progression.
The location of the source isnt so tough once you looking in the right direction.
It just depends i guess on whether you think seti is worthwhile in the first place.
If i were paying for it, id say go the full hog optical. The chances of recognising radio signals traveling light years are just not worth the effort IMO.
We have seen in our own short experience that it dosnt take long for a planet to go quiet, unless it is deliberately announcing itself.
The idea of a galactic society of civilisations all happily conversing by optical laser is a good one with quite a long pedigree, and is one of the more optimistic solutions to the Fermi Paradox. There could be thousands of civilisations out there exchanging data and even uploaded mindstates freely across the light years without ever coming into physical contact. Some call it the Interstellar Internet.
There are two things that strike me about this scenario; in a society where no-body ever meets each other, it is very possible for a civilisation to lie about its characteristics; the Daleks could present themselves as being like cuddly Ewoks, and so on. This would only be a danger if we ever met them, or if they have very-long-range weapon systems (neither of which are impossible).
...secondly an interstellar internet would work best between stars a few tens of light years apart; those poor saps out there in 47 Tucanae probably feel a bit left out, and wonder why everyone ignores their friend requests...
One of the notions that I tend to not agree here is that the beacons of which you speak would need to be much energetic. The distance that you quote (~ 16000 ly) is very far in terms of how the beacon that you mention would broaden and how the intervening ISM would disperse the beam.
The notion to me is creative but not very analytical enough to make any scientific sense. That is just my opinion.
oh i wouldnt suggest for a moment that the signal from 47 Tucanae was in any way ET,
i was just supporting the principle of optical seti as a rational search method...if you are going to be doing seti searches at all.
But, my question is - if this is an ET signal, would that imply that there is no intelligent life besides us in these 16.700 light years?
What's your view from that aspect?
Regarding this particular signal, i would not begin to start thinking anything of it until further observations were made. While i did say you would expect it to disappear, you would also expect it to return if you carried on looking at that point for long enough...who knows how long "long enough" is.
If it were ET, i would just take it that they were the first signal we managed to identify. Actually, as a bit of a skeptic, i would think closer ETs were a lot more likely than before...at least i would know it had happened twice simutaniously in our galaxy
edit, or our region of universe..(sorry, had brain fade...forgot how big MW was there)
Last edited by mutleyeng; 2012-Apr-28 at 06:01 PM. Reason: my ignorance again
Thanks for the post, publius ! Very interesting.
The following quote about 'laser stars' summarises the typical conditions quite nicely:
So, we're talking about energies and ion densities produced by stellar magnitude processes. Also, the sensitivity to initial conditions, would suggest that the specific characteristics of the phenomenon, is likely to be unpredictable across the obs. universe.Laser emission lines are very strong, broad and dominate the spectra. Maximum laser gain occurs in a narrow range of plasma parameters which depends on the ion and the transition. The maximum gain for the 4686 He II transition occurs at 2.5e15 electrons/cm3 and 2.05e4 Kelvin.
This sensitivity to initial conditions leads to the wide variety of
laser emission lines found in emission line stars.
Just looking at the planetary atmospheric 'laser' effect, I notice:
From this, it seems that it would be unlikely to observe a laser type emission for any lengthy periods, also.The process is self-limiting, however, since an increase in the intensity of the incident radiation causes the medium to approach local thermodynamic equilibrium. However, as long as the energy is 'diluted', some sort of laser action will occur.
The 'take home' point here is the unexpected phenomenon itself. Prior to the discovery (some 35 years ago ?), who would've thought such a phenomenon could have been generated naturally ?
How many other phenomena are out there, of which we are entirely oblivious about?
(Eg: like non-biogenic processes, which might sustain large quantities of atmospheric O2 ?)
You sure try a lot to preemptively strike out future discoveries in exoplanet spectra...
Do I ?Originally Posted by MaDeR
In my words above, I was specifically acknowledging that which is undiscovered.
How does this constitute 'preemptively striking out future discoveries' ?