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Extra-Terrestrial Intelligence + 2025 Update

Frank Drake In order to communicate with the other worlds, it requires that both sides should be highly evolved to an advanced technological stage. In 1961, Frank Drake (Figure 09-19a), now President of the SETI (Search for Extra-Terrestrial Intelligence) Institute, proposed a formula for estimating the existence of communicating Intelligent Life elsewhere in our galaxy. This is known as The Drake Equation, which states that

N = R x Fp x Ne x Fl x Fi x Fc x L

where

Figure 09-19a Frank Drake
[view large image]

N = The number of communicating civilizations in the Milky Way
R = The rate of star formation in the Milky Way ~ 6x5/year = 30/year, taking account for higher rate 5 billion years ago.
      2010 Update : The new number is about 10 including some M stars and excluding higher rate of formation.
Fp = Fraction of such stars with planets ~ 0.1, according to the latest search for extraterrestrial planets.
      2010 Update : Recent observations infer that about 90% of all stars have plants.
Ne = Number of habitable planets ~ 0.2, estimated from warm dust around stars.
      2010 Update : It is at least 4 with the new evidence of water on Mars, Europa, and Enceladus.
Fl = Fraction of hospitable planets that have life ~ 3/8, including Earth, Mars, and Jupiter (Europa) among the eight planets.
      2010 Update : The original number of 1 (by Drake in 1961) has been solidified in the intervening years.
Fi = Fraction of arisen life where intelligence develops ~ 1/3, as intelligence life only exists on Earth among these 3 planets.
      2010 Update : The original number of 1 (by Drake in 1961) is preserved by recent investigation.
Fc = Faction of intelligent life that develops communications technology ~ 1.0, by observing our own technology development.
      2010 Update : Drake and others now favor 1 instead of 0.1 estimated previously.
L = The 'lifetime' of such intelligent life ~ 100 years, as we have been broadcasting for around a century.
      2010 Update : This number is the most uncertain term in the Drake Equation. No new estimate is given.

By substituting these numbers into the Drake equation, we obtain a value of N 8 ( 400 according to updated data) civilizations within
ET Drake Parameters Drake Diagram the Milky Way that are currently broadcasting detectable signals. These chosen numbers are the lower limits and worse case scenarios. For example, a techno-logical civilization could last for 1000 years or more, dramatically increasing the value of N. Figure 09-19b depicts the parameters of the Drake equation in a pictorial form. The diagram in Figure 09-19c illustrates the stringent requirements in limiting the number of communicating civilization into a small fraction of the number of stars in the Milky Way.

Figure 09-19b Drake Parameters
[view large image]

Figure 09-19c Drake Diagram


The 2010 updates yield N 3600. Such number actually involves a lot of uncertainty. But as someone points out: "The Drake Equation's biggest contribution is in framing the discussion rather than providing an absolute answer"

[2025 Update]

According to ChatGPT (in Italic text) :



In summary, while the Drake Equation provides a structured approach to estimating the number of communicative civilizations, the uncertainties inherent in its parameters mean that any figure for N remains speculative. Ongoing research and discoveries in astronomy and astrobiology may help refine these estimates in the future.

[End of 2025 Update]

Since the dawn of history, sentient beings have been pondering if there is anybody out there (Figure 09-19f). The search has become more sophisticated by the 21th century. SETI currently uses the multichannel spectral analyzer to scan the sky for radio signal from the "advanced civilization". It also runs a project, which uses programs executing as screensavers on millions of personal computers worldwide to sift through signals picked up by the Arecibo radio telescope. The search is now supplemented by the Allen Telescope Array in Northern California. The array will eventually consist of 350 dishes (by 2011), each 6 meters in diameter, which can be used to listen for signals from several stars in many different radio bands simultaneously. Meanwhile, a privately funded (by the Planetary Society) 180 cm telescope has been installed at the Oak Ridge Observatory to look for flashes of laser beacons from alien civilizations. The instrument will record flashes briefer than a nanosecond because no known natural process would produce such flashes.

Allen Telescope Array The Allen telescope array (Figure 09-19d) began operations in 2007 with just 42 antennas (out of the proposed 350 dishes). It fell victim to the budget cut in 2008. The project managed to limp along for a few years until 22 April 2011 when the SETI Institute and the University of California (at Berkeley) were forced to terminate funding of the $2.5 million annual operating costs. In spite of public misunderstanding about the usefulness of searching for ET, smaller and cheaper SETI searches are still running around the world. Some are seeking alien radio beacons, others are looking for the flicker of interstellar communication lasers.

Figure 09-19d Allen Telescope Array

There are projects looking at specific stars that seem likely to host Earth-like planets; others are doing a less sensitive but broader scan of the entire sky in the hope of catching signals of a type not yet conceived.
Figure 09-19e shows the various small scale SETI projects with annual operating cost and Funding agent.

Small Scale SETI Projects Thanks to the 2300 individual donations (including contribution from Jodie Foster of the 1997 movie Contact) for a total of $206,000 in early August 2011, the Allen Telescope Array may be able to hang on to its dear life if the USAF accepts the offer of using the facility to track space debris around the Earth. This is just one facet to reveal a once great power in decline. Other scientific projects such as the JWST (replacement for the HST) are also in danger of cancellation. The "debt ceiling" debacle threatens more cuts in funding things of science.

Figure 09-19e Small Scale SETI Projects

ET Search In the summer of 2004, a flurry of reports in the media indicate that radio signals (at 1420 megahertz = the hyperfine transition frequency of the hydrogen atom) have been detected three times from a point between the constellations Pisces and Aries. The transmission is very weak and shifting rapidly in frequency. It is pointed out that such drifting of frequency is too rapid to be produced by the rotation of planet and three occasions of detection is not statistically significant. The signals could be generated by a previously unknown astronomical phenomenon, or it could be something much more mundane, maybe an artefact of the telescope itself.

Figure 09-19f Search for ET
[view large image]

    Followings are some suggestions related to the puzzle of "where are they?"

  1. It could be that primitive life may be common in the universe, but intelligent life is exceeding rare. We may be the very few that have advanced to a state where travelling in space is a possibility.
  2. Another theory suggests that many plantets harbouring technologically advanced extraterrestrials exist, but space travel has fundamental limitations or inhereent dangers that we have not yet experienced. In this case, everybody is staying near home.
  3. An alternate explanation about advanced extraterrestrials claims that they don't want to interfere with our development or they just don't have interest in us.
  4. The absence of radio contact may be related to the fact that artificial signals are inherently weak. It is very difficult to detect. If we have ever received anomalous signal from outer space, we still have to uncover the nature of its origin.
Strange Signal There are ten strange signals detected from 2001 to 2014 by the Parkes radio telescope in Australia as reported in a "2015 New Scientist article". The signals are in the form of short duration radio wave lasting for a few milliseconds but with a rather large bandwidth. Components with different wavelength in these radio bursts are spatially separated as they travel through the interstellar medium. The dispersion in wavelength is found to be in an integer multiplication of 187.5 for all the ten measurements (see Figure 09-23a). This is the opposite of ET signaling criterion as shown in Figure 09-20. Nevertheless, these curious signals have generated considerable interests. The short time duration implies that the source cannot be larger then hundreds of kilometers; and the energy output could be enormous depending on the distance of the source from Earth. It could be a new kind of astronomical object, or may involve a new kind of physics, or originated from an unknown human technology. Failing with such kind of explanations, the source could ultimately be attributed to Extra-Terrestrial Intelligence.

Figure 09-23a Strange Signals [view large image]

According to the Optical Dispersion formula, these data points are the manifestions of either the spread of wavelength or variation of optical path length in integer steps.

BTW, The numerals associated with the data points in Figure 09-23a are in the format yymmdd.

News in May 09, 2015 reports that the strange signals were actually originated from a microwave oven in the facility's break room. This is bad news for people who are longing for contact with "Extra-Terrestrial Intelligence". The good news is that integrity is preserved in modern day scientists.

Tau Ceti 2 In all the great oceans of emptiness, stars of type G are the best candidates to look for life - these are stars like the sun. They are of moderate, but comfortable brightness and remain stable for about 10 billion years - sufficient time for complex life forms to evolve. Tau Ceti is such a G-type, sunlike star, devoid of stellar companions and close enough for detailed studies. It was the first object searched for ET radio signals. Though Tau Ceti has about half the sun's luminosity, its habitable zone still comprises about one third AU - this is wide enough that a terran planet may have formed there. But we know from other stars that giant gas planets are common, and they are often very close to their parent star. So if Tau Ceti happens to have a system of planets, a gas giant may orbit within the habitable zone, leaving no space for an additional terrestrial planet. But this giant planet may have moons, possibly of Earth's size, where life may get a start.

Figure 09-23b Tau Ceti
[view large image]

Climate on such a large moon of Tau Ceti's giant planet would not be substantially different from our own. Depending on the parent planet's orbital radius, this world might see the whole range of conditions from the greenhouse of the Mesozoic to the great ice ages of the Pleistocene.
Advanced forms of life, even sentient beings, are not excluded. Figure 09-23b is an artist's rendering of a hypothetical moon in Tau Ceti.

[2024 Update] :

According to ChatGPT (in Italic) :

Tau Ceti is a fascinating star system and one of the nearest sun-like stars to Earth, located about 12 light-years away in the constellation Cetus. As a G-type main-sequence star, similar in temperature and spectral type to our Sun, it has attracted interest due to its stability, age, and relative lack of high-energy flares, which makes it potentially conducive to the development of life on any surrounding planets.

Key features of Tau Ceti that make it interesting for the potential of habitability :

1. Planetary System: Tau Ceti is known to have at least four confirmed exoplanets orbiting it, two of which (Tau Ceti e and Tau Ceti f) are within its habitable zone-the region around a star where conditions might allow for liquid water. Both of these planets are classified as super-Earths, meaning they are larger than Earth but smaller than gas giants, and they may have conditions where life could thrive.
2. Age and Stability: Tau Ceti is somewhat older than the Sun, with an estimated age of around 5.8 to 10 billion years, providing ample time for planetary environments to stabilize and potentially allow complex life to evolve. Additionally, Tau Ceti has low levels of stellar variability, which is favorable for maintaining stable conditions on any orbiting planets.
3. Debris and Cometary Cloud: A significant drawback, however, is Tau Ceti's dense circumstellar debris disk, which suggests a high level of comet and asteroid activity. This debris could create frequent impacts on planets, posing challenges to the development and survival of life, especially advanced civilizations, as it could result in catastrophic events similar to the ones that occasionally affect Earth.
4. Feasibility for Human Exploration: Tau Ceti's proximity and the discovery of planets within the habitable zone make it a prime target for hypothetical interstellar missions. The challenge remains that with current technology, travel to Tau Ceti would take thousands of years. However, as a nearby star system with potentially habitable planets, it's an enticing candidate for future observation and exploration.

In terms of the potential for advanced civilizations, Tau Ceti's planets could theoretically support one, assuming life forms could adapt to or manage the frequent impacts from debris. Studies with next-generation telescopes might reveal atmospheric signatures or other biosignatures that could provide more clues about the habitability and potential for life in this intriguing system.


The advanced beings from Tau Ceti may become the visitors to Earth (aka UFO), according to ChatGPT (once more) :



The topic of UFOs and potential visitors from advanced civilizations is fascinating and complex, as it intersects science, philosophy, and popular culture. Here's a balanced take on it:

1. The Evidence Question
While there have been thousands of reports of UFO sightings, few cases have provided solid, verifiable evidence of extraterrestrial craft. Most reported sightings are ultimately attributed to mundane explanations like aircraft, weather phenomena, or optical illusions. However, there are some incidents that remain unexplained even after investigation. Notably, government-released information, including from the U.S. Pentagon, indicates that certain phenomena were observed that did not fit conventional explanations. Despite this, these reports lack conclusive proof of extraterrestrial origin, leaving room for interpretation.
2. Possibility of Advanced Life
The universe is staggeringly vast, with billions of galaxies and even more planets that may have conditions suitable for life. Statistically, it seems plausible that life could exist elsewhere, and given enough time, some life forms might evolve advanced technology. The idea of "technological civilizations" seems reasonable; after all, humanity achieved remarkable technological advances within just a few hundred years. In billions of years, other civilizations may have developed far beyond our current capabilities.
3. The Fermi Paradox
The Fermi Paradox asks why, if intelligent life is common in the universe, we haven't observed any signs of it. The possible explanations range widely:
" They exist but choose not to contact us: Advanced civilizations may observe Earth without interference (the "zoo hypothesis").
" Communication limitations: Their technology or form of communication might be incomprehensible to us.
" Different priorities: Perhaps interstellar travel and contact with primitive species isn't a priority for them, or they may be bound by ethics that prevent interference.
" Civilizations are rare or short-lived: Intelligent civilizations might be rare, or they may not last long enough to make contact, as they might self-destruct or lose interest in exploration.
4. Challenges of Interstellar Travel
The vast distances between stars make interstellar travel extremely challenging, even for hypothetical advanced civilizations. The closest star to us, Proxima Centauri, is over four light-years away. Unless a civilization has mastered faster-than-light travel (which, according to our current understanding of physics, isn't possible), they would face long journeys even at near-light speeds. Of course, if they are extremely advanced, they might have discovered new physics or technology enabling them to overcome these barriers-but this remains speculative.
5. Why So Subtle?
One might wonder: if extraterrestrials have visited, why are they so subtle? Advanced civilizations capable of crossing vast distances could make their presence undeniable. Instead, sightings are typically vague, sporadic, and non-replicable. If a civilization were truly visiting, why wouldn't they simply reveal themselves? This leads to hypotheses like:
" They want to minimize cultural disruption.
" They're studying us in secrecy, similar to how we might observe animal species without interference.
" The sightings could be misinterpretations, or they might even be mistaken or experimental terrestrial technology.
6. Psychological and Cultural Aspects
The human tendency to see patterns, our fascination with the unknown, and the cultural influence of media all contribute to UFO sightings and alien stories. Since the mid-20th century, movies, books, and TV shows have popularized specific ideas about aliens and UFOs. This cultural backdrop shapes our perceptions and can lead to a "feedback loop," where our beliefs influence our interpretations of phenomena we don't fully understand.
7. The Value of Investigation
Regardless of the source, investigating UFOs can be beneficial for science. Studying these phenomena could lead to new insights into atmospheric science, optical illusions, or even new aerospace technologies. It's possible that unidentified phenomena may reveal new aspects of our own technology or understanding of nature. For example, in studying mysterious signals or sightings, we may eventually detect signs of unknown physical processes or phenomena.

Final Thoughts
While we don't have evidence confirming extraterrestrial visitors, the possibility that advanced civilizations might exist elsewhere remains an exciting question. It's important to keep an open yet scientifically grounded perspective. Rigorous investigation, skepticism, and a sense of wonder can coexist as we continue to explore these intriguing mysteries. In the end, the search for extraterrestrial intelligence encourages us to reflect on what it means to be human, our place in the cosmos, and the possibilities that lie beyond our current understanding.


[End of 2024 Update]

Pioneers Plaque
    The Pioneers-10 space probe was launched on March 1972. In an attempt to contact "advanced civilizations", a plaque bearing engraving such as shown in Figure 09-24 was attached inside. The plaque depicts:
  • an "average" man and an "average" woman standing before an outline of the spacecraft.
  • a diagram showing the hyperfine transition of neutral hydrogen (spin flip of the electrons).
  • a map locating the position of the Sun relative to 14 pulsars and the center of the Galaxy.
  • some symbols representing the binary equivalent of decimal 8.
  • all the planets in the Solar System with distance to the Sun in binary digits.
The probe is now about 10 billion km from Earth and is flying toward the red star Aldebaran in the constellation Taurus. It will reach the destination

Figure 09-24 Pioneers-10 Plaque [view large image]


in 2 million years. So far no "alien" or "advanced civilization" has yet seen the plaque. The last signal was received on January 22, 2003.

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