Newsgroup: it.politica
Titolo: Space Archaeologists Search For Dead Alien Civilizations

Archaeology has gone interstellar.
 
The peculiar behavior of KIC 8462852— a star 1,500 light-years from Earth 
that is prone to irregular dimming — has prompted widespread speculation on 
the Internetthat it is host to an “alien megastructure,” perhaps a vast 
array of orbiting solar panels.
 
Scientists have pointed out various natural, non-alien phenomena that could 
be causing the stellar light show, but the SETI crowd isn’t taking any 
chances. Astronomers have begun using a radio telescope, the Allen Telescope 
Array, to detect possible signals in the vicinity of KIC 8462852.
 
But, the astronomers might be eavesdropping on a tomb.
 
For years, SETI researchers have argued that we can narrow our search for 
alien intelligence by looking for telltale signs of large, sophisticated 
structures built by advanced civilizations. They call this “cosmic 
archaeology.”
 
Yet, even if we were to find such artifacts, there’s no guarantee that the 
civilizations that created them are still around. Floating in space, 
abandoned for millennia, these objects could be the interstellar equivalent 
of the statues at Easter Island or the Egyptian Pyramids.
 
In fact, we might confront the morbid scenario that intelligent life 
periodically emerges on other worlds, but has an unfortunate tendency to 
self-destruct.
 
Sadly, it’s not implausible, given the devastation we’ve wrought during our 
relatively brief span as the dominant species on this planet.
 
That’s why a trio of scientists recently published a guide to help 
astronomers detect alien apocalypses — whether it’s the chemical signature 
of a world filled with rotting corpses, the radioactive aftermath of nuclear 
warfare, or the debris left over from a Death Star scenario where an entire 
planet gets blown to bits.
 
Call it SEETI, the Search for Extinct Extraterrestrial Intelligence.
 
Ironically, the idea of searching for ruined civilizations began at an 
academic workshop on “Building Habitable Worlds.”
 
“One of the concepts that we came up with was detecting the presence of life 
by detecting its own destruction,” says Jack O’Malley-James, an 
astrobiologist at Cornell University and one of the authors of the paper. 
“On top of telling us that there’s life out there, it also would give us a 
clue as to how common or rare we are as a civilization — and how long we 
could expect our civilization’s lifetime to be.”
 
The SEETI study builds upon techniques being developed for the next 
generation of telescopes to detect extraterrestrial biosignatures that would 
indicate the possible existence of alien life.
 
For instance, when looking at an exoplanet, oxygen in its atmosphere that is 
continuously replenished may suggest the presence of photosynthetic 
organisms.
 
SEETI research, however, is not looking for biosignatures — signs of life. 
Instead, scientists have to hunt down necrosignatures — signs of death — 
that would indicate destruction on a colossal scale.
 
Consider a scenario in which biological warfare rapidly wiped out a planet’s 
population. Microorganisms that cause decomposition would gorge themselves 
on alien corpses. In doing so, they would excrete chemical compounds, 
dramatically increasing the levels of methane and ethane in the atmosphere.
 
If the population size of the alien world were comparable to that of Earth, 
the methane and ethane gases would dissipate in about a year, so there would 
be only a short window of opportunity to detect the cataclysm.
 
However, if the biological arsenal included a genetically modified virus 
capable of jumping species, then the planet’s casualties might also include 
its animal life. In that case, the telltale signs of catastrophic biowarfare 
could be visible for several years.
 
An Unhealthy Glow
 
We’ve narrowly averted nuclear war more times than we care to think. Other 
worlds might not have been as fortunate.
 
One clue that a civilization nuked itself into oblivion would be a change in 
the planet’s airglow. You’ve probably seen this phenomenon in dark night 
skies. High-speed electrons and protons, carried by the solar wind, smack 
into oxygen atoms in the atmosphere, causing them to produce a faint green 
light. Particles emitted by nuclear weapons would have a similar effect, 
generating “an order of magnitude increase in airglow brightness,” says the 
SEETI study.
 
An atmosphere’s chemistry would also be altered by the thermal effects of a 
global nuclear war. When a nuclear weapon explodes, the surrounding air 
reaches extremely high temperatures and then cools down relatively quickly. 
This results in a chemical reaction that produces tons of nitric oxide, 
which depletes the concentration of the ozone layer in the atmosphere.
 
These atmospheric changes would be observable for several years after the 
catastrophe, but their visibility would be impaired by yet another 
consequence of nuclear war: the significant amount of dust that would be 
lofted into the atmosphere.
 
Although unlikely, it’s possible that astronomers could see the 
“before-and-after” evidence of a nuclear war, if they observed a planet’s 
transparent atmosphere that later become opaque.
 
Of course, the atmospheric dust also could also be explained by natural 
causes. Instead of nuclear weapons, a large asteroid might have collided 
with the planet — although, granted, that distinction would matter little to 
anyone who was living there at the time.
 
Coming Unglued
 
Some of the doomsday scenarios contemplated by O’Malley-James and his 
co-authors fall into the category of speculative technologies. For instance, 
they raise the specter of the infamous “grey goo” apocalypse.
 
The theory, first postulated in the 1980s, considers the possibility of 
self-replicating nanobots that use carbon-based material to build more of 
themselves. If maliciously programmed, they could be a devastating weapon, 
turning all life into dust.
 
The SEETI paper suggests this disaster could be detectable for thousands of 
years, as some of the dust enters the atmosphere or covers the planet with 
unusually shaped dunes.
 
Among the most dramatic ideas, however, is the complete, physical 
destruction of a world, which could be accomplished by generating sufficient 
power to overwhelm the planet’s gravitational binding energy — in other 
words, blowing it to bits.
 
But, what sort of evidence would exist for this heinous act? One remote 
possibility is the detection of artificial compounds in the debris disc, 
indicating that the planet was once home to a technologically-advanced 
civilization.
 
Other than that, the only option would be to witness the actual destruction. 
If astronomers are unable to determine a natural cause, such as a collision 
with another planet-sized body, then they could tentatively consider 
“extraterrestrial foul play.”
 
“In time, the first evidence of extraterrestrial intelligence may come to us 
from the remains of less prudent civilizations,” the SEETI paper concludes. 
“In doing so, such information will bring us not only knowledge, but 
 wisdom.”
 
Adam Palomar
https://www.facebook.com/profile.php?id=100010386843007
 
 
 

 
https://www.facebook.com/profile.php?id=100010386843007
 
 
Senti Palo, tu che sei del ramo, un ufetto di 3-4 metri di diametro magari con colori fluo, se pole trovà da mettere in giardino?
Il mio bimbo ne sarebbe entusiasta, posso pagare bene!!
Se poi c'è pure l'omino verde in dotazione è pure meglio, ci può giocare il cane!!!
Grazie
 
Salvini

 Archaeology has gone interstellar.
 
Arieccolo :D 
 
Gli fai un piacere di niente agli anti-grillini a dire che ti vuoi
candidare tra le loro file ! Festa grande, proprio. 
 

 Archaeology has gone interstellar.
 
 
A proposito di "archeologia cosmica" 
 
Starry Messages: Searching for Signatures of Interstellar Archaeology
di
Richard A. Carrigan, Jr.,
Fermi National Accelerator Laboratory*, Batavia, IL 60510, USA
 
http://fas.org/spp/eprint/starry.pdf
 
 
(ed attenzione che è un pò scientifichello)