January 18, 2007

Bjork's colonization simulation does not explain Fermi's Paradox

A number of science sites are proclaiming that the Fermi Paradox may have been solved by Rasmus Bjork, a physicist at the Niels Bohr institute in Copenhagen. Unfortunately, his claim does not withstand scrutiny; the Fermi conundrum is still far from being answered.

Bjork is making a point that many others have made before, that ETI's have not had enough time to colonize the Milky Way. What makes his claim different, however, is that he used a computer to simulate the migrational spread of intergalactic probes.

In his simulation, Bjork had a single civilization launch 8 intergalactic probes to search for intelligent life. Once on their way, each probe would send out eight more mini-probes to search for the nearest stars and look for habitable planets. He was careful to set the parameters such that the probes would only investigate the galactic habitable zone of the Galaxy. Bjork also set it up such that the probes could travel at 30,000km/second, or a tenth of the speed of light.

Based on these settings, Bjork discovered that it would take these probes 10Gyr to explore a measly 4% the Galaxy -- roughly half the age of the Universe. This data would indicate that there most certainly has not been enough time for ETI's to thoroughly explore the Milky Way.

His analysis, however, fails to take into account the likely nature of intergalactic exploration and colonization. In Bjork's simulation, he tracks the progress of a mere 72 probes. Given this ludicrously limited strategy, it would take these 8 primary probes and 64 sub-probes 100,000 years to explore a region of space containing 40,000 stars. Such an effort would almost certainly be considered futile by any civilization, and it's doubtful any ETI would embark on such a project.

Instead, what Bjork should have considered is the potential for ETI's to proliferate Von Neumann replicating probes. Advanced civilizations with access to molecular assembling nanotechnology would be capable of launching self-replicating probes. Initially, the spread of Von Neumann probes would be slow, but like any exponential process, progress would eventually explode. It's been estimated that these types of probes could reach all four corners of the Galaxy anywhere from 5 to 50 million years. That's a far cry from Bjork's projected 250Gyr.

So, no, the Fermi Paradox has not been solved. Far from. And it's high time that cosmologists and astrobiologists stopped using technology from Star Trek to inform their research.


Peter S. Jenkins said...

George - yes, I agree. Bjork's assumptions are loaded to produce the result he wants, and also they are implausible. What about Moore's Law? If ET exists, the entire galaxy should be made of computronium by now! The only good potential solution I know of is the simulation argument and possibly also John Smart's theory that post-human civilizations quickly disappear into technological singularities (which is really just a variation of the simulation argument if you substitute "virtual world" for singularity).

As Kurzweil says, we should assume that we are alone in the universe until proven otherwise. This is the approach I took in my Historical Simulations paper,which enabled me to get away from Bostrom's "principle of bland indifference" which assumes that we could be located anywhere in the universe that is compatible with life. Getting away from bland indifference enables us to focus on the ethical issues that we will face here on earth in the next 40 years or so in deciding whether to create historical simulations. This in turn suggests that we are probably in a simulation, which resolves Fermi's paradox, so the approach is somewhat self-reinforcing but logical nonetheless.


Jeff Patterson said...

"Their Made out of Meat!"

Anonymous said...

"As Kurzweil says, we should assume that we are alone in the universe until proven otherwise."

The comment above is just silly. We shouldn't 'assume' anything, starting with the notion that Fermi's Paradox is sound. Unfortunately, in order to believe in Fermi's Paradox one must assume that Humans currently possess all the necessary knowledge/information necessary in order to claim we are currently not being visited by 'others.' The acceptance of Fermi's Paradox also is based on the assumption that we are equal in technological sophistication of extraterrestrial species. The acceptance of Fermi's Paradox is also based on the assumption that extraterrestrials would openly communicate with human beings, clarification, communicate with scientists according to their own pre-concieved notions or that we would even possess the ability to detect their presence.

So if you are a seeker of 'truth', let me hand it to you on a silver platter.

1.) Fermi's Paradox is unsound. (Far too many assumptions)

2.) If Extraterrestrials exist, they will exist in forms independant of human expectations.

3.) If Extraterrestrials exist it is likely they are far more technologicaly advanced than our primitive species, and thus would not consider us equals on any level, the same way we humans don't consider ourselves equal to insects for example. Now, if UFO's are indeed extraterrestrial, then it is likely they view us as a resource, one which they can use/manage as they seem fit.

On the nature of UFO's, a topic supporters of the Fermi Paradox completely ignore, let's discuss another popular fallacy. The lie often told is that it is impossible for extraterrestrial species to travel the vast differences to our world, so therefore UFO's aren't real. Well, people who believe this truly need a good wake up call.

The problem is that such people are, once again, 'assuming.' This time they are assuming just what form of extraterrestrial may be behind the UFO phenomena, a.k.a. 'organic.' When we realize that any extraterestrial race which may visit us is destined to be far superior technologicaly, then such forms will undoubtedly embrace either a merger or complete uplift to an artifical/intelligent machine existance. Such forms of life can literaly travel billions of years, moving from planet to planet as they seem fit. What prevents an organic life form from traveling to the stars shall in no way prevent an intelligent machine of technological superiority.

Open your minds people!

-Jason Gammon

Gary said...

Those trying to contact or detect intelligent lifeforms in other parts of the galaxy are working under the assumption that the civilization would stay at the same technological level for a long period of time, and therefore providing something to detect. (even the word 'civilization' assumes that the intelligence works in groups as ours does)

However, because the technology of that other intelligence would progress toward a singularity, it would likely start to spread out away from its origin at near the speed of light.

(For example, imagine that it would able to assemble remote parts of its intelligence using lasers to assemble particles at great distance, and then transfer a large amount of information to those distances. )

Because it would be spreading out at nearly the speed of light, the civilization would not be detectable because the light and radio radiation from the intelligence would not have reached us until shortly before that _civilization itself_ would reach us.

In this circumstance, you likely would only have a few hundred year 'light window' to detect the civilization before the civilization itself reached your part of the universe.

Then the question would be, would they consider us 'sentient' enough to communicate, merge, or uplift? Considering that current society does not even see apes as near enough to man to uplift, it could be a existential risk.

Anonymous said...

What I find is missing in Bjorks considerations, is any thought about how spread out life might be.

He sais it takes 100000 years to explore 40000 stars (all stars wich are suitable for planets suitable for life (as we know it)).

Well, what if life is spread out enough, that there is highly advanced life on just one out of every 40000 stars (all suitable for life), then we should be found in 100000 years, wich is not that much!

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