The Great Filter: are we rare, are we first, or are we doomed?

Fermi’s Paradox (the fact that we never detected any sign of aliens even though, conceptually, life could be relatively common in the universe) has already been discussed in this blog, as new results come in about the rarity of life bearing planets, the discovery of new Earth-like planets, or even the detection of possible signs of aliens.

There are a number of possible explanations for Fermi’s Paradox and one of them is exactly that sufficiently advanced civilizations could retreat into their own planets, or star systems, exploring the vastness of the nano-world, becoming digital minds.

A very interesting concept related with Fermi’s Paradox is the Great Filter theory, which states, basically, that if intelligent civilizations do not exist in the galaxy we, as a civilization, are either rare, first, or doomed. As this post very clearly describes, one of these three explanations has to be true, if no other civilizations exist.

The Great Filter theory is based on Robin Hanson’s argument that the failure to find any extraterrestrial civilizations in the observable universe has to be explained by the fact that somewhere, in the sequence of steps that leads from planet formation to the creation of technological civilizations, there has to be an extremely unlikely event, which he called the Great Filter.

This Great Filter may be behind us, in the process that led from inorganic compounds to humans. That means that we, intelligent beings, are rare in the universe. Maybe the conditions that lead to life are extremely rare, either due to the instability of planetary systems, or to the low probability that life gets started in the first place, or to some other phenomenon that we were lucky enough to overcome.

It can also happen that conditions that make possible the existence of life are relatively recent in the universe. That would mean that conditions for life only became common in the universe (or the galaxy) in the last few billions years. In that case, we may not be rare, but we would be the first, or among the first, planets to develop intelligent life.

The final explanation is that the Great Filter is not behind us, but ahead of us. That would mean that many technological civilizations develop but, in the end, they all collapse, due to unknown factors (some of them we can guess). In this case, we are doomed, like all other civilizations that, presumably, existed.

There is, of course, another group of explanations, which states that advanced civilizations do exist in the galaxy, but we are simply too dumb to contact or to observe them. Actually, many people believe that we should not even be trying to contact them, by broadcasting radio-signals into space, advertising that we are here. It may, simply, be too dangerous.


Image by the Bureau of Land Management, available at Wikimedia Commons

The Digital Mind: How Science is Redefining Humanity

Following the release in the US,  The Digital Mind, published by MIT Press,  is now available in Europe, at an Amazon store near you (and possibly in other bookstores). The book covers the evolution of technology, leading towards the expected emergence of digital minds.

Here is a short rundown of the book, kindly provided by yours truly, the author.

New technologies have been introduced in human lives at an ever increasing rate, since the first significant advances took place with the cognitive revolution, some 70.000 years ago. Although electronic computers are recent and have been around for only a few decades, they represent just the latest way to process information and create order out of chaos. Before computers, the job of processing information was done by living organisms, which are nothing more than complex information processing devices, created by billions of years of evolution.

Computers execute algorithms, sequences of small steps that, in the end, perform some desired computation, be it simple or complex. Algorithms are everywhere, and they became an integral part of our lives. Evolution is, in itself, a complex and long- running algorithm that created all species on Earth. The most advanced of these species, Homo sapiens, was endowed with a brain that is the most complex information processing device ever devised. Brains enable humans to process information in a way unparalleled by any other species, living or extinct, or by any machine. They provide humans with intelligence, consciousness and, some believe, even with a soul, a characteristic that makes humans different from all other animals and from any machine in existence.

But brains also enabled humans to develop science and technology to a point where it is possible to design computers with a power comparable to that of the human brain. Artificial intelligence will one day make it possible to create intelligent machines and computational biology will one day enable us to model, simulate and understand biological systems and even complete brains with unprecedented levels of detail. From these efforts, new minds will eventually emerge, minds that will emanate from the execution of programs running in powerful computers. These digital minds may one day rival our own, become our partners and replace humans in many tasks. They may usher in a technological singularity, a revolution in human society unlike any other that happened before. They may make humans obsolete and even a threatened species or they make us super-humans or demi-gods.

How will we create these digital minds? How will they change our daily lives? Will we recognize them as equals or will they forever be our slaves? Will we ever be able to simulate truly human-like minds in computers? Will humans transcend the frontiers of biology and become immortal? Will humans remain, forever, the only known intelligence in the universe?


Are Fast Radio Bursts a sign of aliens?

In a recently published paper in The Astrophysical Journal Letters, Manasvi Lingam and Abraham Loeb, from the Harvard Center for Astrophysics, propose a rather intriguing explanation for the phenomena known as Fast Radio Bursts (FRBs). FRBs are very powerful and very short bursts of radio waves, originating, as far as is known, galaxies other than our own. FRBs last for only a few milliseconds, but, during that interval, they shine with the power of millions of suns.

The origin of FRBs remains a mystery. Although they were first detected in 2007, in archived data taken in 2001, and a number of FRBs was observed since then, no clear explanation of the phenomenon was yet found. They could be emitted by supermassive neutron stars, or they could be the result of massive stellar flares, millions of times larger than anything observed in our Sun. All of these explanations, however, remain speculative, as they fail to fully account for the data and to explain the exact mechanisms that generate this massive bursts of energy.

The rather puzzling, and possibly far-fetched, explanation proposed by Lingam and Loeb, is that these short-lived, intense, pulses of radio waves can be artificial radio beams, used by advanced civilizations to power light sail starships.

Light sail starships have been discussed as one technology that could possibly be used to send missions to other stars. A light sail, attached to a starship, deploys into space, and is accelerated using energy in the sending planet by powerful light source, like a laser. Existing proposals are based on the idea of using very small starships, possibly weighting only a few grams, which could be accelerated by pointing a powerful laser at them. Such a starship could be accelerated to a significant fraction of the speed of light in only a few days, using a sufficiently powerful laser, and could reach the nearest stars in only a few decades.

In their article, Lingam and Loeb discuss the rather intriguing idea that FRBs can be the flashes caused by such a technology, used by other civilizations to power their light sail spaceships. By analyzing the characteristics of the bursts, they conclude that these civilizations would have to use massive amounts of energy to produce these pulses, used to power starships with many thousands of tons. The characteristics of the bursts are, according to computations performed by the authors, compatible with an origin in a planet with a size approximately the size of the Earth.

The authors use the available data, to compute an expected number of FRB-enabled civilizations in the galaxy, under the assumption that such a technology is widespread throughout the universe. The reach the conclusion that a few thousands of this type of civilizations in our galaxy would account for the expected frequency of observed FRBs. Needless to say, a vast number of assumptions is used here to reach such a conclusion, which is, they point out, consistent with the values one reaches by using Drake’s equation with optimistic parameters.

The paper has been analyzed by many secondary sources, including The Economist and The Washington Post.


Image source: ESO. Available at Wikimedia Commons.

Is there life out there?

As reported in an article in the journal Nature, Proxima Centauri (pictured), the star nearest to our sun, has an Earth sized planet, orbiting the “Goldilocks” zone (not too hot, not too cold).

The recently discovered planet orbits the mother star in 11 days, an orbit much smaller and much closer to its sun than the orbit of the Earth. However, since Proxima Centauri is a red dwarf, it is much cooler than our sun, which makes this orbit to be just the right size. The planet, named Proxima Centauri b, weights between 1.3 and 3 times the Earth, which makes it likely that it may be a rocky planet. The distance to the star makes it possible that it may exhibit liquid water.


This combination of factors makes it the planet most likely to help us obtain additional information about the possible existence of life outside of Earth. Earth based instruments, such as the European Southern Observatory, ESO, an array of telescopes in the Atacama desert, in Chile, will be able to obtain additional information.

ESO was involved in the discovery of Proxima Centauri b, and likely to play an important role in the discovery of further information about this planet that, in astronomical terms, lies tantalising close to Earth, at “only” 4.2 light-years. Sending a spacecraft out to that planet may also be a possibility, albeit a very challenging one.

The challenges involved in obtaining further information about this planet are significant, but not unsurmountable, as the Economist reports. In a few years, we may have some better answers to Fermi’s famous question, “Where are they?”, referring to the possibility of extra-terrestrial life.


Are we living in a computer simulation?

The idea that the Earth, its inhabitants and the whole universe could be just a computer simulation is not new. Many have argued that intelligent agents simulated in a computer are not necessarily aware they are part of a computer simulation. Nick Bostrum, author of Supperintelligence and professor at Oxford, suggested in 2003 that members of an advanced civilization with enormous computing power might decide to run simulations of their ancestors.

Of course, no computer simulation created by mankind was ever able to simulate realities as complex as our world, nor beings as intelligent as humans. Current computer technology is not powerful enough to simulate worlds with that level of complexity. However, more advanced computer technologies could be used to simulate much more complex virtual realities, possibly as complex as our own reality.

A recent article in Scientific American about this topic includes opinions from many well known scientists. Neil deGrasse Tyson, well-known for the series Cosmos, put the odds at 50-50 that our entire existence is a program on someone else’s hard drive. Max Tegmark, a cosmologist at MIT) pointed out that “If I were a character in a computer game, I would also discover eventually that the rules seemed completely rigid and mathematical,” just as our universe.

This week the topic came to the forefront, at the Code Conference 2016, where Elon Musk said that “we’re probably characters in some advanced civilisation’s video game“.  His argument is that “If you assume any rate of improvement at all, then the games will become indistinguishable from reality, even if that rate of advancement drops by a thousand from what it is now. Then you just say, okay, let’s imagine it’s 10,000 years in the future, which is nothing on the evolutionary scale.

Therefore, if you assume this rate of evolution lasts for a few centuries, computer games will become indistinguishable from reality and we may well be inside one of those.


To be fair, there are many things that could be interpreted as signs that we do live, indeed, inside a computer simulation. The strangeness of quantum computing, the vastness and the many inexplicable coincidences of the universe, the unexplained start of the evolutionary process, are all things that could be easily explained by the “simulated world” hypothesis.

This topic has, of course, already been fully addressed by Zach Weiner in a brilliant SMBC strip.

Pictured, the Marenostrun supercomputer, in a photo by David Abián, available at Wikimedia Commons.

The aliens are silent because they are dead

In a paper recently published in the journal Astrobiology, Aditya Chopra and Charles Lineweaver, from the Australian National University, argue that the reason we have not met intelligent aliens is because, in general, life does not evolve fast enough to become a regulating force on planet ecologies.


If this explanation holds true or if it is, at least, one of the possible explanations, then many planets may have developed life, but in few or none of them has life lasted long enough to be able to regulate greenhouse gases and albedo, thus maintaining surface temperatures compatible with life. If this is true, then extinction is the default destiny for the majority of life that has ever emerged on planets in the galaxy and the universe. Furthermore, only planets where life develops rapidly enough to become a regulating force in the planet ecology remain habitable and may, eventually, develop intelligent life.

(Photo by By Ian Norman, via Wikimedia Commons).