Category Archives: Philosophy

Odds are, there are no aliens

Bayesian reasoning nixes chance for life

…the expectation that life — from bacteria to sentient beings — has or will develop on other planets as on Earth might be based more on optimism than scientific evidence.

Bayesian probability is named after 18th century English mathematician and theologian Thomas Bayes. Yes, you can blame him for bursting your bubble.

But here’s the gist of it. In having ONE earth with ONE example of life and evolution on this planet, we have a sample size of exactly ONE. Statistically, that’s horse feathers; you can’t assume anything about the rest of the universe with a sample size that tiny.

Even by throwing around “magical” words like “billions” or “trillions”, meaning galaxies, stars, exoplanets – it still doesn’t guarantee any success in finding extraterrestrial life.

To borrow from Karl Popper, as long as the existence of extraterrestrial life or intelligence is not falsifiable (meaning you would have to check every exoplanet around every star), you could continue the search for ET forever. I’m not sure that this is in line with the scientific method; ideally you’d be looking objectively at what’s out there and trying to understand what you see from that standpoint.

We may just be all alone on our pretty blue marble.



“Where are they?” – The Fermi Paradox

Enrico Fermi was a famous Italian physicist, known by some as the father of nuclear power as well as the atom bomb.

The story is that he was walking to lunch with some of his colleagues. For some reason, the subject of UFO sightings and aliens came up in conversation, and – as physicists – started to wonder about faster-than-light travel. Suddenly, Fermi exclaimed, “Then where is everybody?”

This is not really a paradox in the regular sense. It’s not a contradiction as much as a question asking for clarification.

“The apparent size and age of the universe suggest that many technologically advanced extraterrestrial civilizations ought to exist. However, this hypothesis seems inconsistent with the lack of observational evidence to support it.”

Of course, this question chooses to deny reports of UFO sightings and contacts with aliens. I’m choosing to leave this alone as well; not through denial, but in search of alternative proofs.

What comes out of the Drake Equation and the Fermi Paradox is: WONDER. This is where real science begins.

If they are out there, why haven’t they contacted us?

Maybe the distances are too far, or there’s some other physical impediment that we have overlooked.

Maybe they just don’t want to, for reasons of their own.

Maybe they are trying to contact us, but we don’t recognize the signal.

The allegory of the cave

What is real and what is imagined? What are the limits of our understanding of what we perceive? And yes, this has everything to do with the search for extraterrestrial life.

This famous allegory appeared in Plato’s Republic. Supposedly Socrates came up with this, but since Plato often put his ideas in Socrates’ mouth, it may just as likely have been Plato’s idea.

And now I will describe in a figure the enlightenment or unenlightenment of our nature:

Imagine human beings living in an underground den which is open towards the light; they have been there from childhood, having their necks and legs chained, and can only see into the den.

At a distance there is a fire, and between the fire and the prisoners a raised way, and a low wall is built along the way, like the screen over which marionette players show their puppets.

Behind the wall appear moving figures, who hold in their hands various works of art, and among them images of men and animals, wood and stone, and some of the passers-by are talking and others silent.

They are ourselves, I replied; and they see only the shadows of the images which the fire throws on the wall of the den; to these they give names, and if we add an echo which returns from the wall, the voices of the passengers will seem to proceed from the shadows.

This applies to the search for extraterrestrial life in this way: We are observing extraterrestrial phenomena, filtered, at the very least, through millions of miles of space, often looking only at data delivered by very complex technology. Many times this data is only a stack of numbers. In order to begin interpreting this data, or shadows on the cave wall, so to speak, scientists have to make a number of assumptions; otherwise, the numbers remain only numbers. In order to interpret this to the public, the need to leave out the numbers and the assumptions that they make, and present only the particular conclusions that they make.

So many times, when we observe stellar phenomena, we are essentially assigning names to the dancing shadows on the wall, often with nothing more than a working theory as to what actually cast the shadows. And scientists are constantly re-working their theories about the sources of these shadows.

So when you read about astronomers explaining stellar phenomena with constructs such as “pulsars”, “magnetars” and “blitzars”, please understand that these are the theories of humans who have never left the Earth. Take it with a grain of salt.

The Drake Equation

The Drake equation was invented by astronomer and astrophysicist Dr. Frank Drake, to estimate the probability of life in our galaxy that might be expected to communicate with us.

“How can we estimate the number of technological civilizations that might exist among the stars? While working as a radio astronomer at the National Radio Astronomy Observatory in Green Bank, West Virginia, Dr. Frank Drake (currently on the Board of the SETI Institute) conceived an approach to bound the terms involved in estimating the number of technological civilizations that may exist in our galaxy. The Drake Equation, as it has become known, was first presented by Drake in 1961 and identifies specific factors thought to play a role in the development of such civilizations. Although there is no unique solution to this equation, it is a generally accepted tool used by the scientific community to examine these factors.”

Wikipedia has a more robust discussion of the equation here:

Some of the factors are well known, such as the average rate of star formation in the Milky Way Galaxy. Some factors began as vague guesses, such as the number of planets around each star, but are becoming more concrete knowable figures. Most of the other factors are actually educated guesses and may continue to be until we discover extraterrestrial life.

The Drake Equation exists mostly as a thought experiment, or as a framework to begin building a Search for Extraterrestrial Life (SETI), so it should be now surprise that Dr. Drake currently works for SETI.

Since most of the factors in the equation are estimates or guesses, the results differ. But generally the result demonstrates that the number of advanced civilizations that might be capable and willing to communicate to be in the order of millions. Or be as low as one.