Archive for the ‘Evolution’ Category

Q: Is it of any coincidence that mathematics is able to describe physical reality – given that both are inventions of the human mind?

Friday, March 5th, 2010

Physicist: There’s a lot of math that doesn’t describe physical reality at all, and even some (few) mathematicians who feel that
“applicability” is just another word for “impurity”.  The ability of math to describe reality is just a consequence of the fact that reality is nice and consistent.

The fact that the math we use (addition, subtraction, geometry, calculus, whathaveyou) works is no coincidence at all.  Mathematics literally evolves in the sense that, if something doesn’t work, then people will ignore it.  So if you have a theory that \pi = 7, great, but no one will use it because it’s patently, provably false.  It doesn’t describe reality (in this case the reality that the ratio of the circumference to the diameter of a circle is \pi), so it goes the way of the Woolly Mammoth.

π=7

I assume that this question is about perceived reality (colors only exist in the brain, whereas in reality there is no “blueness” or “redness”), and not physical reality.  The fact that we can only describe (mathematically and otherwise) the reality we perceive does guide the direction of mathematical research, and as we perceive more we find that the field of math expands accordingly.  For example; number theory wasn’t much more than a hobby before digital communication and RSA encryption, and differential geometry was mostly a nuisance (and anal-retentive over-generalization) until general relativity cropped up.  Now these are both thriving fields of research (in computer science and physics, respectively).

However, just because something works in your head has absolutely no bearing on whether or not it will work in reality (which you would expect if the physical world were created by our minds).  Very good, very reasonable ideas get shot down by experiment every day, and we are constantly surprised.

Philosopher: If we assume the external world exists (independent of our minds), Math’s correspondence to reality is no more coincidental than the correspondence to reality of theories stated in any other language.  This isn’t dependent on the existence of mathematical objects, and it’s not dependent on Mathematical truths existing independently of humans (though I think they do).  If we assume the external world is merely an “invention of the human mind”, then the correspondence of Math to the world is even less coincidental, since the same thing is the author of both.

Posted in -- By the Physicist, Evolution, Math, Paranoia, Philosophical | 1 Comment »

Q: Do aliens exist?

Saturday, January 30th, 2010

Physicist: Yuppers.  In as much as the probability that they don’t is effectively zero.

The statistics on this are a little weak, since we only have one real data point.  If you define intelligent life as tool-using, then (based on the age of the oldest tools and the oldest fossils, and the progress of the Earth to date):  Intelligent life has existed 0.06% of Earth’s history, and animal life has existed for about 16% of Earth’s history.  Moreover, the vast majority of life on Earth (and the toughest) is microbial.  So by “yuppers”, I mean that space bacteria almost certainly exists.

As far as the fancy aliens (with their lasers and tentacles) that I assume the question is really about: probably.  The universe is crazy big.  However, stars are far apart (especially around here), and the likelihood of finding intelligent life is really low.

In the last decade there have been some surprising results from the panspermia people.  It seems to be entirely possible, even likely, for life to get kicked from planet to planet and even from star to star.  The three difficulties are getting off a planet, surviving in space, and landing somewhere else.  During a major impact the material immediately around the impact is vaporized.  A little farther out and things are pulverized.  Just beyond the “automatically dead zone” is a thin ring where material from the planet’s surface can be thrown into space smoothly (no more than a couple hundred G’s) and without excessive heating.  Although no animals could survive the shock, massive G forces have very little impact on single celled life (too small to slosh).

There’s a wide variety of life from Earth that does fine in space.  Things like Water Bears, and some bacteria can put up with the cold and radiation, and are more than happy to drop into a state of suspended animation for the trip (forever if they have to).  The classic example is a few cells of Streptococcus that survived on the moon (on Surveyor 3′s camera) between 1967 to 1969.

Something you may notice, if you collect large meteorites, is that although the surface tends to be pretty messed up, the interior is frequently quite intact.  Although the fall looks pretty impressive, the heat and fireball don’t have time to cook the meteors all the way.  In fact the hottest parts of the meteor vaporize during the fall, which serves to keep it cool (like sweat, but like… a rock version).  Although it’s unlikely for living things on any one rock to make it through all three stages intact, keep in mind that there are actually many rocks flying around that have been knocked off of planets in the past.  There are so many, that one of the cheapest ways to collect samples from Mars or Venus is to go to Antarctica.  (If you find a rock sitting on top of a 3 miles of ice, where do you think it came from?)  One of the biggest “life is out there” stories came from exactly this source.

Here’s the point: If there’s life anywhere it’s likely to spread everywhere, like… well, like life.  Panspermists think that life may have started on some other planet around some other star, and that this life then infected the Earth.  This would help explain why the Earth was covered with sophisticated (microbial) life almost immediately after it was capable of supporting life at all.  Or to spin it around, if there’s life here (check) it’s had over 3 billion years to get blasted out into the nearby universe.

 

Mathematician: There are compelling reasons to think that life exists on other planets (perhaps even on a huge number of other planets). If life spontaneously arose on earth from a soup of molecules through an evolutionary process, then all you need for life to be created is the right planetary conditions, the proper raw materials, and a sufficient amount of time. The right conditions may include things like being close enough to a sun that the planet is reasonably warm, but far enough from that sun so that it isn’t  burnt to a crisp. The right materials probably include carbon and water among other things. In any event, once you get these things right, you just add time (a billion years probably would suffice) and viola, life is born. That means that for earth to house the only living organisms in the universe, these requirements would have to have been met one time and one time only in all the billions of galaxies that have formed during the 14 billion year history of our universe. That sure sounds pretty unlikely.

Here’s another way to think about it: there is some probability p that a randomly selected planet will form life on it within a billion years. If p is sufficiently small, then there would be almost no chance of any life forming, including our own, and hence we should not exist. If p is sufficiently large, then life would exist almost everywhere in the universe. The only way that we should expect to be the one and only planet with life is if p is just right to produce about one planet with life over all the years and on all the planets that have ever existed. But we have no evidence whatsoever indicating that p should be perfectly balanced in this way, indicating that the chance of alien life is a good one.

But does technologically advanced alien life exist? Well, if life occurs on many other planets, then we should expect technologically advanced life to occur on at least some of them. Whatever caused natural or sexual selection to select for high levels of mammalian intelligence on earth could lead to intelligent aliens as well. On the other hand though, if technologically advanced civilizations tend to wipe themselves out fairly quickly (say, within a hundred thousand years) or if the process that creates highly intelligent life requires sufficiently rare conditions, then advanced aliens could certainly be the exception rather than the rule.

Posted in -- By the Mathematician, -- By the Physicist, Astronomy, Biology, Evolution, Physics | 1 Comment »

Q: Why?

Wednesday, December 2nd, 2009

Mathematician: From time to time, people like asking us questions such as “Why?”, while steadfastly refusing to explain what the heck they are talking about. The best example of this was a naked guy who approached our “Ask a Mathematician / Ask a Physicist” booth at Burning Man. In an attempt to respect everyone’s right to not explain themselves, we’ll make a series of guesses about what those folks might be trying to get at, and briefly respond to each of these possible questions.

1. “Why do we exist?”

Mathematician: We exist because our ancestors were at least slightly better at passing down their genetic material than other people. If the environment of earth happened to be just a tad bit different, then other genes besides our own would have been favored, and we would not be here today. If the environment had been a little more different still, then not only would we not be here, but the human species would not even be here. Some other creatures (possibly of great intelligence) would now be romping around this planet. In conclusion, we exist because the process of evolution works, because our planet happened to have the right conditions for evolution to begin, and because conditions changed over time such that human genes (and more specifically, our ancestor’s genes) happened to be favored for survival. We all got very, very lucky.

Physicist: If the many-worlds hypothesis holds (it totally does), then everything that’s possible happens in some version of the universe.  If you can ask the question “Why do we exist?”, then you’ve already restricted your attention to the (possibly very small) set of universes where intelligent life exists.  This argument is called the “anthropic principle“.  So the reason we exist is because there is at least some vanishingly small chance that we could.

2. “Why does existence exist?”

Mathematician: Nobody knows. A related question that nobody knows the answer to is “why does consciousness exist?”  For example, why aren’t we like computers, going about our business without ever “feeling” anything or having any “internal, personal experience”? There are a few possible answers to this question. Perhaps we don’t really have consciousness and we just think we do (though this answer strikes me as bullshit). Another possibility is that consciousness is something that emerges automatically (call this a property of the universe) when you have a sufficiently complicated system with the right components, and that we have consciousness merely because evolution happened to produce those special components in our brain (so in that case consciousness is a side effect of some useful brain parts). A third option is that consciousness was created by the process of evolution because it has a specific survival use (perhaps it is a handy way to get creatures to spread their genes).

Physicist: What else is existence going to do?

3. “Why is the universe the way it is?”

Mathematician: I consider this to be a deep mystery. According to an old Finnish creation story, the sky is a piece of an egg and the sun is its yolk, but this strikes me as unlikely. Perhaps physicists will one day be able to shed light on this question.

Physicist: If there’s some kind of rhyme or reason behind the beginning, then go figure out who was doing the reasoning and ask them.  If, however, the universe was randomly generated, then it may follow the same rules for random generation that everything else in the universe does.  The probability that a particle is generated is proportional to the number of states it can be in.  So if an electron can be in two states and a pion can be in three, then the pion is 3/2 times more likely to be created than an electron.  More states means more entropy.  The universe may be the way it is because our particular set of physical constants (speed of light, gravitational constant, planck’s constant, etc.) cause the universe to have tremendous complexity (many many states). If the constants were different, then everything might have already fallen into black holes, or complex molecules may not form, or there may be no stars or solar systems, etc.  Each of these circumstances have a much lower entropy than the universe we see today. So (perhaps) the universe is the way it is so that it can maximize it’s own entropy.

4. “Why are we the way we are?”

Mathematician: We have eyes because there is a Sun near our planet that is bouncing light off of everything, and it is mighty useful (for survival) to be aware of this radiation. It is so useful, in fact, that eyes have been created (from scratch) multiple times on the evolutionary tree. But why do we have two eyes, rather than one? In part, it probably serves as a back up system: since vision is so critical to survival on this planet, and since eyes can easily be pierced or go faulty, it’s much safer to have two. Another reason to have two eyes is because it allows us to have true 3D vision (which again, likely increases a creatures chance of survival). Why do we have arms and hands? Because our ancestors walked on four legs (which is useful for fast running, and our arms developed from these front legs) and manipulating the world around us is damn useful (thank you fingers!). Why do we have legs? Well, because that’s one of the best mechanisms that evolution found for getting around. These arguments can be repeated for most body parts. The point is that we are the way we are because the environment of earth during our evolution made the traits that we have useful for survival. We could have been very different had conditions been a little different, but things like eyes and legs are so incredibly useful that it is very likely we would have at least had those.

Physicist: Evolution favors what works.  Things that work, and have thus evolved over and over in different places here on Earth, include: limbs, blood, eyeballs, nervous systems, sex, socializing, fighting and fleeing, eating and pooing, smelling, breathing, moving, not looking at the sun, … As for why we’re bipedal, hairless, and whatnot: sometimes these things happen.  If you’ll notice, there aren’t a lot of other creatures that share these traits.  If we were something else we’d wonder about that too.

5. “Why am I me and not someone else?”

Mathematician: Just chance, mostly, but you are also changing into a new person every moment, with new cells, new memories, new ideas and new behaviors.

Physicist: You’re no one at all before you’re born.  Who you are now is who you’ve become.

Posted in -- By the Mathematician, -- By the Physicist, Evolution, Philosophical, Quantum Theory | 2 Comments »

Q: What is the meaning of life?

Thursday, October 29th, 2009

Mathematician: I’m glad you asked. The theory of evolution with natural selection sheds some light on the question of why humans exist, which in turn relates to the meaning of life. First of all, let me get this out of the way: while evolution is still called a “theory”, it has a tremendous amount of evidence in support of it (including gradual transitions in the fossil record, radiocarbon dating, DNA analysis, laboratory experiments, etc.) and, as biologist Richard Dawkins is known to say, it is only a theory in the sense that the “theory of gravity” is a theory. From a scientists perspective, evolution is a fact. But what does that have to do with the meaning of life? Well, evolution tells us that human beings share a common ancestor with apes, not to mention with pigs, dogs, cats, rats, plants, and bacteria. If historically the conditions on earth had been very slightly different than they were, the best traits for survival would have been different also, and therefore we would expect that some other species besides humans (possibly with intelligence as great as ours) would now dominate this planet. Hence, evolution tells us that humans have the capacities that they do now simply because those capacities helped our ancestors survive long enough to have children, or made them more effective at finding mates.

I believe most people will agree that “What is the meaning of life?” is a question that is meaningless when it is applied to the lives of rodents, insects, or bacteria. As we are simply evolutionary offshoots of these creatures, what makes us think that this question will have any more significance when applied to us? The primary characteristic that differentiates us from these other creatures is our powerful brains that have incredible capacity for abstract though (including the ability to consider questions like “what is the meaning of life?”). Each of us exists today because our ancestors managed to survive. Their survival occurred both because they were well adapted to their environment, and because they got very, very lucky. Our existence then is, in some sense, a happy accident, and lacks the deep cosmic significance that questions like “what is the meaning of life?” presuppose. Fortunately, however, our brains are very adept at discovering meaning in all sorts of places. Life does not require an all encompassing, universal meaning or purpose in order for us to find that our own lives are meaningful, and that is a truly wonderful thing! We can feel totally fulfilled despite being little more than happy accidents of evolution. Of course, “meaning” is a very real and important emotion, but that does not make it an objective property of things. Fortunately, there is no reason to fret over life itself having no ultimate purpose. We ourselves can find something that fills us with a sense of purpose, which for practical purposes is just as good.

Physicist: Every now and again a question comes along that implies more than it asks.  Questions like: “What’s that blue thing?”, or “Who ate this?”.  If there’s nothing blue or eaten around, then these questions don’t make sense.  The same is true of the classic: “What is the meaning of life?”.

Posted in -- By the Mathematician, -- By the Physicist, Evolution, Philosophical | 1 Comment »