Saturday, March 21, 2015

Faeries in Phase Space

A few weeks ago, Professor Ben Zuckerman spoke at my school. He is one of the editors of the popular book "Extraterrestrials: Where Are They?" which explores in part the Fermi paradox: Why haven't extra-terrestrials tried to contact us yet? While he gave two lectures, I only attended one, where he went over many of the ideas in his book, explaining the rarity of technological life and the improbability of us ever making "contact".

I went to the colloquium talk rather interested. In honesty, I kind of misunderstood the intention of the talk (I thought he was going to be arguing against the existence of extraterrestrial life), but I was not disappointed. There were a lot of interesting ideas brought up about how to make contact or about what sorts of development projects we should pursue. And while I think some of them were really bad, they were thought-provoking. (Dr. Zuckerman of course recognizes the flaws of these, saying they are just stage 1 prototype designs).

The talk was very well done and I won't touch on it too much. What I really wanted to address was an audience question asked by one of the professors at my university. First let me provide some background.



In the colloquium, Dr. Zuckerman made reference to SETI. Among other things, SETI is scanning the night sky for signals that may be traceable to alien civilization. This search can be characterized in terms of a "phase space."

A phase space generally is an extension of space to include additional degrees of freedom.  This consideration is very useful in statistical mechanics, especially at the quantum level.
A particular phase space graph I found online.
Just for illustrative purposes
The most common is to consider position and momentum together in a 6-dimensional space.

To figure out exactly what it meant in the context of the search for extra-terrestrials, I had to do some searching, but it seems (according to this article) that they are classifying signals in terms of position in the universe, the frequency of the signal, and a few things related to the quality and category of the signal.  So, saying we explore a region of phase space is saying we explore a region of the universe, in a particular range of frequency, looking at particular characteristics of the signal.

As you might imagine, this is a lot of variables with a huge range of possible values. Thus, exploring all of it is essentially impossible

Dr. Zuckerman addressed this during his talk, saying that the amount of phase space is huge ("like the ocean") and the amount of phase space that SETI had actually explored so far is very, very small ("like a glass of water").

After the talk, one of the professors here (call him Dr. W [X sounds too sinister]) mentioned to Dr. Zuckerman that there are several people who claim that what SETI is doing is not really science, but pseudo-science. Their reasoning is this: there is so much phase space out there that no matter how much we look, we can always just say that we haven't explored it all yet. Thus, the existence of extraterrestrials can never really be disproven and SETI can keep asking for government funding forever.

I heard this, I thought "fair enough point". There is no real way to falsify the existence of extra-terrestrials. It can't ever be proven that they don't exist. Therefore, it is an unscientific claim to say that they do, and especially to say that they would have these kinds of characteristics.

For full disclosure, I do not believe that there is intelligent life in the universe besides on this planet (though it'd only take one to prove me wrong!), so I was kind of glad at this point being brought up. I chuckled at it.

I don't remember exactly how Dr. Zuckerman responded to this, besides to say that that was pretty uncharitable to the people at SETI. They're looking for things because there's a possibility of them finding something.

I didn't think about this then, but I was later reminded of the the Higg's Boson. Before it was confirmed, it was also an unfalsifiable hypothesis. No matter how high they raised the energy, the people at CERN just kept saying that they hadn't probed a large enough energy region. This went on for decades, folks. They failed to find it, said they needed to raise the energy level, then looked again. If there were actually no such thing as the Higg's Boson, then we would still be looking for it because "we haven't explored high energy energy ranges".

The primary difference is that scientists thought they had good enough reasons to believe in the Higg's Boson, and many scientists do not believe there are good enough reasons to believe there is extra-terrestial intelligent life.

Anyway, Dr. W continued pressing about this, and said (sarcastically) something to the effect of:

"Well, how do we know that there aren't fairies, but we just haven't explored enough of the phase space yet?"

What does that mean?

What does it mean for a fairy to be living in an unexplored region of phase space?

If a fairy were living in an unexplored region of phase space, how would we know that it was a fairy, specifically?

What even is a fairy and how we we distinguish a fairy in some unexplored part of phase space from, say, a gnome in some unexplored part of phase space, or a djinn in some unexplored part of phase space.

Critically, how are we to distinguish a fairy in some unexplored part of phase space from an alien in some unexplored part of phase space?

This is a fairy.
It seems clear to me that Dr. W is not actually asking anything. He is using the word "fairy" to mean precisely "ridiculous thing that doesn't exist". His question can be basically rephrased "How do we know that there aren't ridiculous things which don't exist?" Well, the way he is using the word, they don't exist by definition.

But to really go further in to this question, if we assume it has real content and isn't just a roundabout way of saying "your idea is silly", this raises an interesting point. To talk about fairies in some other region of phase space is to already divorce the word from its traditional definition of the spritely things that live in gardens and steal away human babies as changelings. We're no longer strictly talking about things with butterfly wings.

Since Dr. W opened up this line of speculation with his question, what if a fairy is actually something bizarre, like a particular distribution of momenta? Fourier transforming them to position space (meaning the space we directly see) renders them as incomprehensible collections of atoms, but looking at them in phase space (meaning looking at the momenta of those particles) we see distinct beings going about their way and interacting. They're all around us all the time, but we don't notice them because they're in another region of phase space.

What does this even mean? I don't know. But now it's been introduced by Dr. W as a possibility.

And of course we must ask, what if we actually did discover something like that? How would we ever know that it was a fairy? Wouldn't we instead call it something else? "Blips," or something equally uncreative?

More to it, what if "fairies" are a species of intelligent life forms who use radio signaling on their home planet, and we one day intercept these signals from a region of the universe and a place in the electromagnetic spectrum that we have not previously looked? If we discovered these, would we not instead recognize them as "aliens"?

It seems that the only way to really talk about fairies is to talk about tiny little wee-folk who live in forest glades and meadows, who tend to the flowers and fly on butterfly wings at twilight. If these exist, then we would expect someone to be able to find them. They'd be physical things and would leave signs of themselves. Biologists have found a large number of intriguing species of animal life, but so far nothing that fits the description of a classical fairy. Not even possible fairy scat or shards of fairy pottery. I think the world as we know it is pretty inconsistent with a world where fairies exist, and so I think it's a fairly safe bet that there are no fairies.

While I am not at all of the opinion that intelligent life exists elsewhere in the universe, the objection that the search for it is like the search for fairies is really just begging the question. We can't say that the universe is inconsistent with a universe with aliens (like we can for the earth and fairies) because we still know so little about it.

There are some other points I could bring up that came out from the talk, but that's really all I wanted to mention this time.

5 comments:

  1. The difference between fairies (or gnomes, or dragons, or unicorns, etc.) and aliens, is that the former are human inventions - or so we must assume, in the absence of any evidence to the contrary. Our idea of what fairies are comes from folklore, stories, and artists' depictions, but they were likely invented long ago to explain phenomena for which we have since come up with better explanations. Even if something like fairies did exist in a different phase space, one where we can't directly perceive them, I would argue that they are not really "fairies" unless we can find evidence that someone in the past DID perceive them (ie without technologically advanced equipment that might be available in the future) and that this was the basis for the fairy in folklore.

    Aliens are a more abstract concept, which can describe any life that is not based on Earth. Or, possibly, life on Earth that exists in a different phase space which we can't directly perceive, although I'm sure this would be a matter of debate. The possibility of alien life is not based on science fiction books and movies about aliens; the alien in modern folklore is a result of the statistical probability that life *could* exist elsewhere in the universe. All visual representations of the "alien" in pop culture are merely guesses at what such life might look like, which is why there's such variety in their depictions.

    I'm curious why you "don't believe in" extraterrestrial life. I'm sure you're familiar with the Drake equation. There are no physical laws whatsoever that forbid the existence of life elsewhere in the universe. The statistical likelihood that there is only one planet that ever has, or ever will host life is ridiculously improbable. And if such life does/did/will exist, the time and distance separating us from them are likely so vast that we'll never encounter each other, so naturally the universe would appear empty to us, isolated as we are in our little bubble of perceivable spacetime.

    As a physicist, I'm sure you're aware of all this already - so I'm curious how you can dismiss the possibility so easily.

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    1. "I would argue that they are not really "fairies" unless we can find evidence that someone in the past DID perceive them (ie without technologically advanced equipment that might be available in the future) and that this was the basis for the fairy in folklore. "

      This is an excellent point that I didn't consider.

      "I'm sure you're familiar with the Drake equation."

      I am familiar with it. The Drake equation itself is fine. The problem is that it's basically a long series of probabilities, most of which we have no way at all to even guess. Until we've discovered somewhere around a hundred other intelligent species, we can't fill in any of the numbers that the Drake equation uses.

      "There are no physical laws whatsoever that forbid the existence of life elsewhere in the universe."

      Not that I know of, no. But life might just be so incredibly rare that we are the only lifeforms. It might be that the conditions for life to begin are so infinitesimal that even if we iterated a billion billion universes like this one, we still wouldn't see life arise again. It might be. I don't actually know, and neither does anyone else.

      And that's just basic microbial life. That's to say nothing of intelligent life, the sort that can send E&M signal or leave their planets gravitational pull. We don't know how rare that is, either. We don't know the probabilities of that happening.

      The problem is that we have a single data point, so we can't begin drawing any conclusions from it yet.

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  3. Along this line of thought, anyone who is interested in nonexistent "THINGS" that
    keep cropping up as being perceived by a wide variety of people ,UFOS , ghosts, cryptids ,etc.
    The author John Keel has an interesting theory as to what the hell is going on and what most
    of these interactions are about.

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  4. ET's = Fairies was a particularly funny episode of the TV show Supernatural. Season 6 Episode 9 available on Netflix.

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