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Release date: November 6, 2011

Is the search for extraterrestrial intelligence, or SETI, solid science, pseudoscience, or something else, as Massimo argues in his book "Nonsense on Stilts"? What are the theoretical foundations and empirical evidence that justify a multi-decade research program, and what are its chances of succeeding? Have we learned anything thanks to SETI? Also, if the universe is infinite, what problems does this pose for utilitarian ethics?

Julia's pick:  "Ask a Mathematician / Ask a Physicist"

Massimo's pick: "Doctor Who and Philosophy: Bigger on the Inside (Popular Culture and Philosophy)"


Reader Comments (12)

The link to download the MP3 results in a 404.

November 7, 2011 | Unregistered CommenterChris

Correct URL to download the MP3:

November 7, 2011 | Unregistered CommenterChris

Thanks Chris, the links ha been corrected now.

November 7, 2011 | Registered CommenterAdmin

Do scientists think that all life on earth evolved from the same primordial soup bowl? Was it one singular event and then all life evolved from that point? If so, then perhaps this is relevant to the probability of life forming on a planet. I don't see why the existence of life should preclude another primordial event. Though, I suppose that fledgling life, were it co-located with existing life would normally, though not necessarily, be at a disadvantage.

November 10, 2011 | Unregistered CommenterJ. Benson

Great episode, as always!

One comment on probability ... just because life has formed on earth, it doesn't mean that there is a non-zero probability of its occurrance. Any unique event (or any event that can occur in an arbitrarily large finite number of ways) in an infinite sample space will have a probability of zero. It's a subtle difference between "zero probability" and "impossible". And even if there is an infinite number of possible planets that could produce life, if the sample space (all possible planets) is of a higher order infinity, then the probability is still zero.

IMO, SETI is doomed to failure. But just the fact that the ramifications would be so HUGE make it worth at least a token effort. We flush money away on many things that are much so more ridiculous!

November 19, 2011 | Unregistered CommenterScott

er, "so much more ridiculous".

November 19, 2011 | Unregistered CommenterScott

The only problem with the Fermi Paradox is that it is quite possibly not a paradox at all.

For a paradox to actually be a paradox, it has to compare two assertions that are not only contradictory, but they both must also be arguably true. In the case of the Fermi, the two assertions are:

a. Intelligent life should be common in the universe.
b. We have not seen any evidence of it.

One of these assertions is arguably untrue. No, it's the other one! The key words are "any evidence".

December 2, 2011 | Unregistered Commentersherlock

I've been catching up on past episodes and enjoyed this one.

Drake's Equation has featured in a couple of BBC science programmes in recent years. Each time there was no critical analysis of the validity of the equation. It seemed to be presented as a valid piece of science. After all, it's been around for decades and people still talk about it. But it always struck me as arbitrary. It appears to put the question of extraterrestrial life in a mathematical form, thus making it more scientific, but I think this is an illusion. So, it was good to hear the discussion in the podcast, the first time I've heard anyone question the validity or value of the equation.

I tend to agree that SETI is unlikely to yield results, largely because we may simply be looking for the wrong kind of evidence. On the other hand, it's a bit like doing the lottery... if I buy a ticket each week it's minimal expense but with HUGE potential reward (however unlikely). As to the question of wisdom of SETI... as long as we don't "answer" the call, I guess there's no harm in it.

If we found ET it would change our view of the universe (and perhaps kill off the current mainstream religions) but, Oh, the temptation to answer the call. Survival of advanced civilisation may depend on it being an all-powerful dictatorship (the "future filter") and this may not bode well for a more primitive world such as our own.

July 12, 2012 | Unregistered Commenter5ecular
I have listened to all the podcasts from the latest backward. When i got to this one i couldn't keep my tongue any longer.

Dearest Massimo,

We do not merely have a sample size of one. This is a straw man. We have a universe full of the same stuff that acts according to the same rules. If a dog talks, that means dogs can talk, even if you never find another example. The particular conditions which brought about the individual instance will always have a chance of being replicated elsewhere, regardless of how probable.

The fact that there is one advanced civilisation *is* evidence because it shows that intelligent life is possible. We have no evidence that intelligent life is not possible, nor that it is rare, nor any other thing. The principle of mediocrity is not only perfectly valid but perfectly necessary because we have no evidence that we are Not typical. In other words, since there is 0.00000001 evidence for other advanced civilisations and 0.00000000 evidence otherwise, 100% of the evidence is on the side of there being other intelligent life. It doesn't make any difference whatever how big the evidence is; when it is the *only* evidence it is the only thing rational to believe.

Furthermore, since typical things are much more likely to occur than non-typical things the principle of mediocrity is the only possible null hypothesis, you cannot get rid of it, especially without any evidence to the contrary. Anything *other* that the principle of mediocrity would be bizarre, precisely the opposite of what you've claimed.

We do not assume that we are typical, we assume that in absense of any evidence to the contrary it is most likely that we are typical. That's a different argument than the one you're trying to attack. I believe there's a name for this... Want to jump in, Julia? To claim statistical liklihood of other intelligent, communicative life is hardly the same as "we are a representative sample of the universe". That's a positive claim, not a probabilistic claim. Different animals.

We can not claim any random fact about Earth applies elsewhere, nor does anyone make that claim, to the best of my knowledge. Obviously some things are a lot more common than others. Claiming that life exists can't be put in the same box as the claim that skateboarders exist or any of the other inifnite human peculiarities. That your Facebook profile exists elsewhere? No. That intelligent life exists elsewhere? Maybe. That life exists elsewhere? Definitely! For someone who teaches logical rational thinking classes this is an unforgivable sin.

"You simply cannot say that Earth is representative..." Nobody says that. People say that some of the common characteristics of Earth are likely to occur elsewhere which is not only rational, it's logically necessary. We have the same stuff and the same laws of physics. For us to NOT be representative would be an anomoly, not the other way around. The more specific you try to get, the more absurd the argument is, but to say that there is not other intelligent life is to say not only that we aren't typical, but that we are unique. That is a claim that cannot be supported by statistical probability or any other evidence ever obtained or derived by man. Absense of evidence is not evidence of absense and all that jazz.

The same rationalle applies to the infinite nature of the universe. We cannot imagine either what it could mean for the universe to End nor what it could mean for the universe to not End but since we cannot sense or test any End, the alternative is statistically more likely. Our evidence, scanty though it is, is that things don't end in that sense. Only in the human scale where "end" really means "change to a different state" do we experience an "end". The non-existance, or whatever it may be at the End of the universe cannot be evidence because we have no sense or experience of such a thing. 0.00000001 evidence for infinity, 0.00000000 evidence for the contrary.

Every event is a unique event. "it could very well be the case that that was the only one" You're treating all the levels of possiblity as if they are the same probability again which is a layman's mistake. Shame.

"You cannot make the leap from a sample size of one to that there is however small a probability that there is more than one" Yes, yes you can. I just did, and showed how it is not only possible but logically necessary.

I won't belabor the point any further. This was a common thread throughout the episode and it pissed me off much more than similar failings in other episodes so i decided to write about it.

I have another bone to "pick". At least two of your picks have been in academic walled-garden journals with buy-in costs of $40 for a single article!
September 8, 2016 | Unregistered CommenterKaiser Basileus
David Brin's analysis of the Fermi Paradox, published in 1982, still feels relevant:
June 5, 2017 | Unregistered CommenterJim Gregoric
Perhaps the aliens have digital or other technology that prevents their signals from leaving their home star systems.

Some people think we should actually try to contact the aliens instead of hoping to observe some random signals from them:

NASA thinks they will find aliens soon:

Stephen Hawking indeed does say the aliens might try to hurt us:

Actually, thus far SETI has really only looked at a relativity small number of exoplanets. With the new funding coming into SETI, it may soon return some results.
January 28, 2018 | Unregistered CommenterJameson
Von Neumann said intelligent aliens are already among us....
and they are called 'hungarians'
June 2, 2019 | Unregistered Commenterskypickle

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