Geoffrey Landis’ percolation theory as to lack of detectable Type III Civilisations

Perhaps the best reasoning as to why an advanced civilisation possessing the ability for interstellar travel would fail to colonise an entire galaxy is Geoffrey Landis’ percolation theory. Landis makes the assumption that interstellar travel is short haul only. We might be able to make direct flights to alpha Centauri or epsilon Eridani, but anything […]

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There are a lot of assumptions here: For one, that alien biology will have comparable physical requirements to our own. If biotic life isn’t limited to Earth-sized planets in the habitable zone—a restriction that precludes the icy moons Europa and Titan—the number of life-harboring worlds could actually be much higher.

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It has been repeatedly proposed to expand the scope for SETI, and one of the suggested alternatives to radio is the biological media. Genomic DNA is already used on Earth to store non-biological information. Though smaller in capacity, but stronger in noise immunity is the genetic code. The code is a flexible mapping between codons and amino acids, and this flexibility allows modifying the code artificially. But once fixed, the code might stay unchanged over cosmological timescales; in fact, it is the most durable construct known. Therefore it represents an exceptionally reliable storage for an intelligent signature, if that conforms to biological and thermodynamic requirements. As the actual scenario for the origin of terrestrial life is far from being settled, the proposal that it might have been seeded intentionally cannot be ruled out. A statistically strong intelligent-like “signal” in the genetic code is then a testable consequence of such scenario. Here we show that the terrestrial code displays a thorough precision-type orderliness matching the criteria to be considered an informational signal. Simple arrangements of the code reveal an ensemble of arithmetical and ideographical patterns of the same symbolic language. Accurate and systematic, these underlying patterns appear as a product of precision logic and nontrivial computing rather than of stochastic processes (the null hypothesis that they are due to chance coupled with presumable evolutionary pathways is rejected with P-value < 10–13). The patterns are profound to the extent that the code mapping itself is uniquely deduced from their algebraic representation. The signal displays readily recognizable hallmarks of artificiality, among which are the symbol of zero, the privileged decimal syntax and semantical symmetries. Besides, extraction of the signal involves logically straightforward but abstract operations, making the patterns essentially irreducible to any natural origin. Plausible ways of embedding the signal into the code and possible interpretation of its content are discussed. Overall, while the code is nearly optimized biologically, its limited capacity is used extremely efficiently to pass non-biological information.

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Using the Very Large Telescope Interferometer (VLTI) in near-infrared light, the team of astronomers observed 92 nearby stars to probe exozodiacal light from hot dust close to their habitable zones and combined the new data with earlier observations. Bright exozodiacal light, created by the glowing grains of hot exozodiacal dust, or the reflection of starlight off these grains, was observed around nine of the targeted stars.
From dark clear sites on Earth, zodiacal light looks like a faint diffuse white glow seen in the night sky after the end of twilight, or before dawn. It is created by sunlight reflected off tiny particles and appears to extend up from the vicinity of the Sun. This reflected light is not just observed from Earth but can be observed from everywhere in the Solar System.
The glow being observed in this new study is a much more extreme version of the same phenomenon. While this exozodiacal light—zodiacal light around other star systems—had been previously detected, this is the first large systematic study of this phenomenon around nearby stars.
In contrast to earlier observations the team did not observe dust that will later form into planets, but dust created in collisions between small planets of a few kilometres in size—objects called planetesimals that are similar to the asteroids and comets of the Solar System. Dust of this kind is also the origin of the zodiacal light in the Solar System.
“If we want to study the evolution of Earth-like planets close to the habitable zone, we need to observe the zodiacal dust in this region around other stars,” said Steve Ertel, lead author of the paper, from ESO and the University of Grenoble in France. “Detecting and characterising this kind of dust around other stars is a way to study the architecture and evolution of planetary systems.”

By analysing the properties of the stars surrounded by a disc of exozodiacal dust, the team found that most of the dust was detected around older stars. This result was very surprising and raises some questions for our understanding of planetary systems. Any known dust production caused by collisions of planetesimals should diminish over time, as the number of planetesimals is reduced as they are destroyed.
The sample of observed objects also included 14 stars for which the detection of exoplanets has been reported. All of these planets are in the same region of the system as the dust in the systems showing exozodiacal light. The presence of exozodiacal light in systems with planets may create a problem for further astronomical studies of exoplanets.
Exozodiacal dust emission, even at low levels, makes it significantly harder to detect Earth-like planets with direct imaging. The exozodiacal light detected in this survey is a factor of 1000 times brighter than the zodiacal light seen around the Sun. The number of stars containing zodiacal light at the level of the Solar System is most likely much higher than the numbers found in the survey. These observations are therefore only a first step towards more detailed studies of exozodiacal light.
“The high detection rate found at this bright level suggests that there must be a significant number of systems containing fainter dust, undetectable in our survey, but still much brighter than the Solar System’s zodiacal dust,” explains Olivier Absil, co-author of the paper, from the University of Liège. “The presence of such dust in so many systems could therefore become an obstacle for future observations, which aim to make direct images of Earth-like exoplanets.”

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Searching for the ruins of alien civilisations

The glow we see at the Milky Way’s core began its voyage towards us at a time when prehistoric hunters were chasing mammoths across Europe’s ice sheets. The galaxy itself spans 100,000 light years, and its nearest equivalent, the great disc of Andromeda, is 2.5 million light years away. We see it as it looked when humanity’s ancestors walked the African savannah. When interstellar archaeologists tilt their telescopes to the sky, they are gazing into the deep history of the cosmos, but to find a civilisation more advanced than ours, they have to tilt their imaginations into the future. They have to plot out a plausible destiny for humanity, and then go looking for it in the cosmic past.

Searching for the ruins of alien civilisations

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Scientific American: Which religions are more open to the idea of alien life? David Weintraub: Asian religions for the most part are easily accommodating. In Buddhism, for example, there are lots of worlds. Reincarnation is an important part of that view of life. I could be reincarnated in principle anywhere in the universe. There’s nothing […]

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So are we alone? Well, there is one other possibility, at this point. I’ve lately been trumpeting my revision of Clarke’s Law (which originally said ‘any sufficiently advanced technology is indistinguishable from magic’). My revision says that any sufficiently advanced technology is indistinguishable from Nature. (Astute readers will recognize this as a refinement and further advancement of my argument in Permanence.) Basically, either advanced alien civilizations don’t exist, or we can’t see them because they are indistinguishable from natural systems. I vote for the latter. This vote has consequences. If the Fermi Paradox is a profound question, then this answer is equally profound. It amounts to saying that the universe provides us with a picture of the ultimate end-point of technological development. In the Great Silence, we see the future of technology, and it lies in achieving greater and greater efficiencies, until our machines approach the thermodynamic equilibria of their environment, and our economics is replaced by an ecology where nothing is wasted. After all, SETI is essentially a search for technological waste products: waste heat, waste light, waste electromagnetic signals. We merely have to posit that successful civilizations don’t produce such waste, and the failure of SETI is explained. And as to why we haven’t found any alien artifacts in our solar system, well, maybe we don’t know what to look for. Wiley cites Freitas as having come up with this basic idea; I’m prepared to take it much further, however. Elsewhere I’ve talked about this particular long-term scenario for the future, an idea I call The Rewilding. Now normally one can’t look into the future; in the case of the long-term evolution of technological civilization, however, that is precisely what astronomy allows us to do. And here’s the thing: the Rewilding model predicts a universe that looks like ours–one that appears empty. The datum that we tend to refer to as ‘the Great Silence’ also provides the falsification of certain other models of technological development. For instance, products of traditionally ‘advanced’ technological civilizations, such as Dyson spheres, should be visible to us from Earth. No comprehensive search has been done, to my knowledge, but no candidate objects have been stumbled upon in the course of normal astronomy. The Matrioshka brains, the vast computronium complexes that harvest all the resources of a stellar system… we’re just not seeing them. The evidence for that model of the future is lacking. If we learn how life came to exist on Earth, and if it turns out to be a common or likely development, then the evidence for a future in which artificial and natural systems are indistinguishable is provided by the Great Silence itself.

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The Ultimate Telescope



I think it’s fair to say that, given your ‘druthers, you’d want an instrument that could map exoplanets in the kind of detail you get with Google Earth, with enough resolution to actually see the Great Wall of the Klingons, in case they’ve built one.

Could we construct such a telescope … ever?

An interesting discussion and worth a read, but in actual fact we sort-of already have telescopes that are bigger than this.  Like, almost twice the diameter.

Y’see, it used to be that to get your telescope to work you needed one big reflector. Bigger the reflector, better the resolution (in the strict physics sense of the word resolution, meaning the ability to distinguish objects as separate from each other).

The biggest single reflector is, as you probably know, the Arecibo radio telescope.  And that’s kind of unwieldy and pretty impractical, not least because you can’t point it at anything other than whatever is directly overhead.

Around the 1970s though, computing power got good enough that a new type of telescope became possible, and led to the construction of arrays of smaller dishes, probably the most famous example of which is the imaginatively-named Very Large Array in New Mexico.  With a bit of clever programming, the images from all those individual dishes can be stitched together to in effect make the whole thing behave like one really big dish, only with the benefits of being directional and much cheaper to build and maintain.

As computing power has increased, more and more of these array telescopes have been built.  MERLIN, one of my favourites because it’s British, takes the input from seven older dishes spread across a couple of hundred miles of the Midlands, puts it all together, and gives you an effective telescope diameter that would be impossible to construct as a single dish (well, unless you had a budget of trillions of pounds and felt like dooming Birmingham and the rest of central England to permanent darkness).

But even with this technology, we’re limited by the size of the Earth, with a diameter of about 8,000 miles, right?  And that’s pretty far short of 100 million miles.

Well, not exactly.  Because Earth is moving.  In six months time you will be 186 million miles away from where you are right now, round the other side of the Sun.

That’s a pretty long exposure photograph, I know, but to get the maximum resolution of deep-space objects, this is exactly what astronomers do.  We use the motion of our own planet in orbit to get an effective telescope diameter the same size as the diameter of our orbit.  Which is pretty mindblowing to me.

Now, this is currently only really used for radio frequencies, but I would expect it’s not impossible to use a similar system for visible frequencies.  Not that it would be much use for identifying features on a planet, as that planet will likely also be spinning on an axis and certainly it will be orbiting a star, and because its orbit would need to be in a fairly narrow range of distances away from that star for it to be habitable, its orbit would be of roughly the same order as our own (a few months to a few years), so over a 6 month exposure that planet will be a blur, but still, we could at least see that it’s there.  From the way its atmosphere reflects and transmits light we could detect possible signs of industry.  We could make informed guesses about oceans and landmasses.  We could even potentially detect signs of life.

And all of that makes me pretty damn excited.

The Ultimate Telescope

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The Ultimate Telescope

I think it’s fair to say that, given your ‘druthers, you’d want an instrument that could map exoplanets in the kind of detail you get with Google Earth, with enough resolution to actually see the Great Wall of the Klingons, in case they’ve built one. Could we construct such a telescope … ever? Here’s what […]

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In terms of the search for extraterrestrial intelligence (SETI), it may no longer be a matter of answering the “are we alone” question, some scientists say. Rather, just how crowded is the universe?

And if ET is out there, it may be possible to reach out with direct “radio waving” to potentially habitable exoplanets. This form of cosmic cryptography, called “Active SETI,” involves no longer merely listening for a signal but purposefully broadcasting to, and perhaps establishing contact with, other starfolk.

“It’s a subject of discussion, I’ll put it that way,” said Seth Shostak, senior astronomer at the SETI Institute in Mountain View, Calif. There have been many workshops and symposia over the years to discuss Active SETI, he said, and because it has a highly emotional component, “it’s like a third rail in a way,” he said.

Shostak told that he feels the topic is not something to worry too much about.

“But there may not be that perception in the broader public … that we have discussed this to death. They haven’t seen these discussions nor participated in them,” he said.

But exoplanet detections are making news around the world, Shostak said. “That’s putting the whole question of life in space in front of the public in a way that perhaps wasn’t true 20 years ago.”

Still, trying to figure out what’s the best thing to do, in terms of Active SETI, is a work in progress, Shostak said. “What is the best way to communicate? What do you do…just ping them with a carrier wave and you encode Wikipedia? If you are going to do it, what’s the best way to communicate?”

“[Hawking]’s right about our immaturity as a species,” Impey told, “but I think the argument is moot since intelligent civilizations are likely to be so sparsely distributed that communication in either direction is difficult or unlikely.”

Active SETI, Impey said, “makes us feel a little more proactive, but I think it’s a long shot worse than buying a lottery ticket.”

For Impey, the “promising approach” is not conventional SETI or broadcasting, but detection of civilizations by their energy or technology imprints, “and that avoids all the issues of intention and communication and the anthropocentric tangle people get into with that.”

“I am for passive SETI programs, and in fact would advocate for renewed government funding after a 20-year lapse,” Dick told “That’s because the existence of extraterrestrial intelligence is one of the great unsolved mysteries of science.”

Dick said that the current NASA astrobiology hunt is centered on microbes, but surely there should be an effort to go beyond micro-organisms and search for complex life with whatever means are available.

“On the other hand, I would not propose government funding for messaging extraterrestrial intelligence. I think we need to find ET first, and then have a period where a team consisting of scientists, social scientists and humanities people consider what the message should be,” Dick said.

“Having said that, it would be very difficult to regulate individual or institutional projects that wish to attempt messaging extraterrestrial intelligence, and I would not advocate attempting to regulate,” Dick said. In his opinion, there is an equal chance that ET will be good or bad.

“We do not yet know enough about the evolution of altruism on Earth, much less among other possible intelligent life forms, to say ETs will all be good,” Dick said. “That is a hope rather than a fact.”

But haven’t we already revealed ourselves with TV signals, military radar and other outputs into the cosmos? Even music is wafting across the universe, purposely directed toward a specific star.

That is true, Dick said, but it’s not the same as sending a directed beam to a habitable exoplanet target.

“Still, the idea of planet Earth cowering and afraid to engage the universe is not a planet I would want to live on. SETI attempts are part of our rising cosmic consciousness, and as such cannot be stifled,” Dick said. “That this is the subject of such controversy…it’s an indication of how seriously the subject of intelligent life in the universe is now taken!”

“But Active SETI is not science,” said Michaud. “It is an attempt to provoke a response from an alien society whose capabilities and intentions are not known to us.”

Those most eager to send high-powered messages want their efforts to have consequences, Michaud said, not just for themselves, but for the entire human species. “There is no scientific or historical evidence telling us that the consequences of contact will be those they prefer." 

Michaud says that an alien society able to detect our signals almost certainly would be more technologically advanced than our own, and might be capable enough and patient enough to send  probes across light-years of space. Scientists and engineers have shown that robotic spacecraft able to reach nearby stars would be feasible for a civilization only slightly in advance of our own.

Michaud takes issue with the old claim that we already have been detected or that detection is inevitable. Experts have shown that the normal signals emitted by Earth are too weak to be heard at interstellar distances without colossal antennas, he said.

"Sending deliberate, unusually powerful signals is a decision that belongs properly with all Humankind,” Michaud said. “We should have an open debate about whether or not to call attention to ourselves by making our civilization more detectable than it already is.”

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