Interstellar Archaeology

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Interstellar Archaeology

Postby longhaircowboy » Fri Jan 29, 2010 10:52 pm

Here's an interesting article I found at FAS.
http://www.fas.org/spp/eprint/starry.pdf
It discusses possible alternate avenues to search for other life in the universe. Here's the summary.

Searching for signatures of cosmic-scale archaeological artifacts such as Dyson spheres or Kardashev civilizations is an interesting alternative to conventional SETI. Uncovering such an artifact does not require the intentional transmission of a signal on the part of the original civilization. This type of search is called interstellar archaeology or sometimes cosmic archaeology. The detection of intelligence elsewhere in the Universe with interstellar archaeology or SETI would have broad implications for science. For example, the constraints of the anthropic principle would have to be loosened if a different type of intelligence was discovered elsewhere. A variety of interstellar archaeology signatures are discussed including non-natural planetary atmospheric constituents, stellar doping with isotopes of nuclear wastes, Dyson spheres, as well as signatures of stellar and galactic-scale engineering. The concept of a Fermi bubble due to interstellar migration is introduced in the discussion of galactic signatures. These potential interstellar archaeological signatures are classified using the Kardashev scale. A modified Drake equation is used to evaluate the relative challenges of finding various sources. With few exceptions interstellar archaeological signatures are clouded and beyond current technological capabilities. However SETI for so-called cultural transmissions and planetary atmosphere signatures are within reach.

"Starry Messages: Searching for Signatures of Interstellar Archaeology" by Richard A. Carrigan, Jr., Fermi National Accelerator Laboratory, December 1, 2009.


It is interesting and worth a look see.
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Re: Interstellar Archaeology

Postby Nemo » Sat Jan 30, 2010 12:04 am

I would think that any serious search would probably have to involve more than looking for radio wave signals. The Dyson structures would also seem logical for any civilization just a bit beyond ours which needs the energy. You'd have to be able to discriminate something like this from a dense asteroid belt, etc.

Interesting.
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Re: Interstellar Archaeology

Postby longhaircowboy » Fri Feb 05, 2010 10:44 pm

It would appear that someone may have already found a Dyson structure. This from Wikipedia:
The Cygnus Bubble is a temporary name for a nearly perfectly spherical planetary nebula found in the Crescent Nebula (NGC 6888) within the constellation of Cygnus. It has yet to be given an official designation by the International Astronomical Union.[1]

It was discovered independently by amateur astronomer Dave Jurasevich and professional Mel Helm in 2008.[1]

Its near perfect symmetry has led it to be considered a possible candidate for a Dyson sphere constructed around a star by an advanced civilization.[2]

There also variants of the Dyson structure. There's the shell, the swarm, and the bubble. Freeman Dyson thought that eventually some civilization would require the full output of their star which would lead to the creation of a Dyson structure. Hopefully they can figure out what the Cygnus Bubble is as it may lead to an advanced civilization.
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Re: Interstellar Archaeology

Postby Nemo » Sat Feb 06, 2010 12:19 am

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Re: Interstellar Archaeology

Postby Access Denied » Sat Feb 06, 2010 4:05 am

longhaircowboy wrote:It would appear that someone may have already found a Dyson structure.

This appears to the source of the speculation...

The Cygnus Bubble - Natural or Artificial?
http://www.dailygalaxy.com/my_weblog/20 ... bject.html

Doesn't look very symmetrical to me.

longhaircowboy wrote:Hopefully they can figure out what the Cygnus Bubble is as it may lead to an advanced civilization.

Who's "they"? Looks like another one of these...

Spherical Planetary Nebula Abell 39
http://antwrp.gsfc.nasa.gov/apod/ap010123.html
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Re: Interstellar Archaeology

Postby lost_shaman » Sat Feb 06, 2010 6:04 am

Access Denied wrote:Who's "they"? Looks like another one of these...

Spherical Planetary Nebula Abell 39
http://antwrp.gsfc.nasa.gov/apod/ap010123.html


Hey AD,

I agree with you. I somehow doubt that Hα and O-III gases would pass for a manufactured Dyson Sphere. That's just my take, why it's soo spherical is still an interesting question to pursue.
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Re: Interstellar Archaeology

Postby Access Denied » Sat Feb 06, 2010 6:32 am

Yeah, it’s still an awesome find though. Here’s the APOD on it…

A Bubble in Cygnus
http://antwrp.gsfc.nasa.gov/apod/ap081113.html
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Re: Interstellar Archaeology

Postby Nemo » Sat Feb 06, 2010 7:00 am

lost_shaman wrote:Hey AD,

I agree with you. I somehow doubt that Hα and O-III gases would pass for a manufactured Dyson Sphere. That's just my take, why it's soo spherical is still an interesting question to pursue.


Right. Spectrum emission would show what it consists of and the gasses you would expect in a nebula would not function or look like the artificial constructions that would be made to collect energy and transmit it. For a long time during it's construction would look like a cloud of very small solid objects which wouldn't be very easy to see at this stage. Sort of like asteroids but smaller. They could appear bigger if they had huge film collectors but these would also act like solar sails which you wouldn't want.


[Mod Edit: trimmed quote]
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Re: Interstellar Archaeology

Postby longhaircowboy » Tue Feb 09, 2010 10:32 pm

Access Denied wrote:
Doesn't look very symmetrical to me.

It does look spherical. And both those pictures look quite similar. Any idea if the first one is an actual picture or not?
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Re: Interstellar Archaeology

Postby Access Denied » Wed Feb 10, 2010 4:35 am

Well, it's a real "composite" image. More info here...

http://www.lostvalleyobservatory.com/pa ... tbubblenb/

Here's what I meant by not too symmetrical...

UndesignatedBubbleFC_kbqmh2546.jpg
UndesignatedBubbleFC_kbqmh2546.jpg (38.79 KiB) Viewed 4370 times

I centered the red circle on the little blue star in the middle that the planetary nebula (gas, dust, plasma cloud) surrounds so you can see it better.
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Re: Interstellar Archaeology

Postby longhaircowboy » Thu Feb 11, 2010 10:31 pm

Yeah I got what you meant by symmetry thats why I said its spherical. But apparently the folks at the link you provided don't share your definition of symmetry. I found this in the second paragraph-
1) An unusually symmetrical planetary nebula, ie, a small dying star throwing off it's atmosphere as it becomes a white dwarf (such as Abell 39)

Somebody needs a Websters.
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Re: Interstellar Archaeology

Postby Nemo » Fri Feb 12, 2010 4:32 am

For a planetary nebula it is unusually symmetrical. They often have lobes and jets and are quite often unsymmetrical or have little shape at all as with the Crab Nebula, Eagle Nebula, Horsehead, Orion, etc.
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Re: Interstellar Archaeology

Postby lost_shaman » Tue Feb 16, 2010 8:16 am

To be fair IMO from what I've read about Dyson Spheres, a Dyson Sphere wouldn't really be a Spherical rigid structure in the first place (although that is one interpretation of such although quite impractical), but rather more like an artificial asteroid belt made up of individual solar collectors or several such artificial asteroid belts.

I just wanted to point this simple observation out. The Cygnus Bubble is probably too symmetrical to be a functional Dyson Sphere in the first place even though as AD points out it is not perfectly symmetrical.
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Re: Interstellar Archaeology

Postby longhaircowboy » Wed Feb 24, 2010 10:42 pm

Did you know that Freeman Dyson also proposed the Dyson tree which would make comets habitable?
He did indeed describe the spheres as clouds of asteroid size habitats.
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Re: Interstellar Archaeology

Postby Access Denied » Thu Feb 25, 2010 5:13 am

The “Cygnus Bubble” is some 5 light-years across so pretty cold out there…

http://en.wikipedia.org/wiki/Dyson_tree

“A Dyson tree might consist of a few main trunk structures growing out from a comet nucleus, flowering into branches and leaves that intertwine, forming a spherical structure possibly dozens of kilometers across.”

Don’t think you could see one in another solar system from here.

The optimal orbital radius for a Dyson swarm, shell, or bubble would be 1 AU in our solar system.

(the avearge distance between the Earth and the Sun)
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