From Bacteria to Bach and Back - The Evolution of Minds; Daniel C. Dennett; 2017; W. W. Norton; 413 pgs, index, notes
I have always been interested in the evolution of humanity, and especially that of language and reasoning. FBBB tackles this very problem.
The book introduces (to me at least) the concept of "competence without comprehension". At its simplest, an elevator is competent at moving people up and down, but does not comprehend what it is doing. The same can be said for Watson answering questions on Jeopardy. One of the messages of Dennett is "don't worry about machines taking us over", which relies heavily on this concept.
For me, as a software guy, I was struck by how many times Dennett relied on software and hardware analogies taken from my industry. I too have often pondered these obvious similarities. For example, in computing, routine chores (like printing an essay) are passed off to sub-processors (purpose built and programmed chips) so the main CPU (a remark from the Department of Redundancy Department?) can do other things. A good human example is catching a hit baseball. A good player can, within a fraction of a second, "calculate" where that ball is going and where she has to be to catch it. They can then run to that spot, perhaps with a single refining glance at the ball, turn and catch it. No logical thought goes into any of this. No formula is used to calculate when and where the parabolic arc of the ball will cause it to intersect with the ground. Those calculations are farmed out and unconscious.
DNA itself is essentially a binary digital code... slightly less complex than Morse.
Another thought, which I raise in my book, is the sub-processing associated with interpreting incoming data from the outside world… i.e.: incoming sensual info. We have dozens of senses, and they are all working at once. One of the tricks of the trade in brains and computers is to manage the avalanche of incoming data and separate the wheat from the chaff on the fly. If we could not do this, we would all go nuts (schizophrenia may be an example of this).
Evolution is a master at getting the balances and trade-offs just right… a daunting task and a necessary one if you are going to be you (i.e.: your sense of self awareness). This sense is an illusion, but it is a tough one to kick. (Of course, evolution does no such thing, but it is hard to think about it without get all anthropomorphic.)
Another key component to our minds is Bayesian mathematics. Once pooh-poohed by math purists, it is, nevertheless, in common use by computers today for many different purposes. We use it all the time in our heads, and smarter people are at least somewhat aware of this. Here is the idea: You get a new piece of information in the "game of life". It could be anything at all, like say, a stock price goes up. You note this information. It does not trigger any action per se, other than you mumbling to yourself "oh, gold went up". But in your head, many of your other beliefs may be slightly adjusted (e.g.: "perhaps I should invest more in commodities", or some such). This too will affect other ideas in your head and so on. We do it without thinking or rigor. Computers can do it better because it is an extremely computationally-intensive chore. Each adjustment of a "dial" in you head affects the dials near it, which means they must be adjusted… but this means the original dial is affected and it must be adjusted again… on and on until the adjustments are to small to measure (in computing, this is called "relaxing a network").
This book is not an easy read. It is very thought provoking. One of the central themes in my book The God Con is that con artists and lying have shaped out mental evolution. I am happy to report that Dennett says nothing to contradict my hypothesis, and he even supports it to a degree. The idea here is that we are unique in the animal world in that we have empathy. We can imagine ourselves as another, and ask "What would I do or feel in that circumstance, if I were him or her". This ability is crucial to establishing our self-identity. You cannot understand a con without this ability. The ideas are intertwined. Dennett even discusses the Nigerian Prince scam, for example, and why it is still alive today.
Dennett goes on to discuss cultural evolution and memes in some detail. For you computer fans: memes are applets that can run on any virtual machine (aka: your brain). Our brains are an onion of virtual machines within virtual machines. P-code (Pascal's pseudo-code) died years ago, but the idea came back with a vengeance with scripted languages for the internet. This resurgence is driven by the fact that computers are blindingly fast compared to the 19080s.
The evolution of language has been deemed "the hardest problem in science". Nobody knows how it happened, or when. As little as 50,000 years ago, language may have been rudimentary at best. But the point is, it did evolve, and Dennett offers a plausible explanation for how that happened.
A line I liked:
Consciousness may not be real, but it is remarkably efficient to act as if it did.
George Carlin once said: "For years, I thought the most important organ in my body was my brain, until I realized one morning 'Look who is telling me that!'"
One last point Dennett makes, and I agree, is that it should be illegal to pass off a computer as a human being. In a year or two, it will be possible to appear to make anyone say or do anything with a computer simulacrum. As I write, an unflattering doctored video of Nancy Pelosi is making its way around the internet, and the wanna-believers are lapping it up. Thanks Facebook! This is the just pointy tippy-top of the iceberg.
As books go, this one is as deep as they get: Man trying to fathom his own mind.
Michael Lewis has written some great books (Moneyball, The Big Short etc). I cannot really count this one among them. Nevertheless, it was interesting. Heavy leading and lots of white space make the 219 pages a short read.
This book a basically a collection of anecdotes about Trump taking power.
The first section focuses on the DOE. When Trump took power, he resented having to spend money on transitions (which he is required to do by law). He wanted to keep the money for himself! As a result, there was no smooth transition between administrations. Quite the opposite, in fact.
The first thing the Trump administration asked for was a list of DOE names that had attended any climate related discussions!
Like all departments, the DOE had prepared a primer on what the role of the DOE was. But no one showed up to see it! Rick Perry attended a meeting to brief him. He spent mere minutes familiarizing himself with the department. One official was ousted from her physical office by Eric Trump's brother in law who took it. No one knew why.
The DOE does a lot of things, like making sure reactors don't melt down, and that no bomb material "gets lost". Over the years, the DOE has recovered enough material to make 160 bombs. It is populated by some very smart people. They made sure, for example, that Iran lived up to its part of the deal… until Trump killed the deal. Trump likes to do things in half measures. DOE interviewees point out the dangers of cutting corners, and the huge risks involved when you do.
It is hard to build a fence. It is easy to knock it down. And it is stupid to knock it down if you don't understand why it is there.
The same story unfolded at the USDA (Department of Agriculture). Everyone was waiting to hand over power, and no one showed up… for a month. Soon, the USDA board was occupied by a long haul trucker, an AT&T clerk, a gas company meter reader and a cabana boy. The USDA is responsible for a lot of things, like crops, and nutrition, food stamps etc., and it is now being run by the least competent people imaginable who all hate climate change
The Department of Commerce sounds dull. It does have trade responsibilities, but mostly it is a data bank (data from agencies like NOAA and NASA). Information is their currency. And they have a lot of it. They got the same treatment as the other departments. Wilbur Ross runs it. He and Trump are cut from the same cloth.
Fun fact: Really rich people do not want to be listed in the Forbes 500. Only three in the history of the magazine have fought to get on the list: Saudi Prince Alwaleed, Donald Trump and Wilbur Ross!
The problem is this: Scientific data can be used for many things. Like predicting weather to help farmers make timely planting decisions for example. Huge amounts of data were made public, and scientists used that data to make the world better (you will have to read the book for details), but Trump et al smelled climate change, removed all references to it from all web sites, and removed the aforementioned data from the cloud.
There is an interesting conflict building. AccuWeather gets its data from the feds. But they make money selling that information and the feds give it away for free. So AccuWeather sought to stop the feds from doing that.
Soon, you can expect to see headlines like "Hurricane coming! If you want to know where and when, subscribe to AccuWeather now!".
It will take many years to undo the damage that Trump has done to the US and the world.
Dinosaurs: A Concise Natural History; Fastovsky and Weishampel; 2012; Cambridge University Press; 375 pgs; Index, glossary
We live in the age or mammals. Or do we? Birds are literally dinosaurs and there are twice as many species of birds as mammals. So perhaps we still live in the Age of Dinosaurs. And if we do, you should know a little of how it came about.
Here is how it did NOT happen: It did not happen 6,000 years ago, but 220 million years ago. It did not happen in the twitch of the lips of Barbara Eden. It happened after the table was set (which took place over billions of years) and dinosaurs evolved over 160 million years before most disappeared.
This is a straight up university text book. It is the best one out there that I know of. It is full of a lot of terminology, dates, bones, pictures, bios etc. A fulsome coverage of the state of knowledge of Dinosaurs and their kin.
In the last half century or so, the number of Dinosaur genera has doubled. If you would like the answers to what they ate, when they lived, how they survived, how warm was their blood; how they chewed, ran, walked, raised their young, digested, etc and how we think we know this stuff… this is the book.
It is pretty dry of you are not interested in the topic. I liked it.
This is the great man's attempt to explain the two theories to the lay person in 1916. The treatment of Special Relativity is more or less complete and not hard to follow.
Aside: No real math is involved in the book. But a good physical imagination does not hurt.
The treatment of the General Theory is quite cursory, mostly because the General Theory is much, much more complex that the Special Theory.
I have read such explanations many times. It was interesting to read them in Einstein's own (translated) words.
The only point of interest for me is noting that, in 1916, the metaphor for rapid travel was railroads. When it came to freefall (zero-g), there were no comparators. Today, the idea of weightlessness is common, and a spaceship is the usual vehicle for motion related metaphors.
Einstein used basic physics, and a preternatural ability to cut to the bone of an argument, to take the fact that the speed of light is constant regardless of you motion and turn it into a simple paper that was not fully accepted by his fellow physicists for another decade.
Sunsets can be fabulously beautiful. Get the conditions just right and they are awe inspiring. Every other woman's profile on dating sites cite "walks on the beach at sunset" as a favorite activity. "Spiritual" people have been known to pity the poor slobs (i.e.: people like me) who cannot see the greatness of god or the glory of nature in a sunset. It is true… I do not see that. I think I see a little more.
When I see a sunset, perhaps off a beach in Hawaii, my thoughts have been known to wonder down a number of paths. Here is one spontaneous, extemporaneous, well thought out, chain of idle musings, while staring at the horizon.
My first thoughts go to the beauty. When the clouds are just right, with the sunlight, forced to colors from the redder end of the spectrum, bouncing off them, the sense of 3D hugeness is hard to avoid. The sun itself goes pear shaped as it touches the horizon. All of that is caused by water and warm wet air. The clouds are suspended micro-droplets of water. Evaporating water changes the density of the air and its refractivity. Nice, very nice, but boring to watch. So again my mind wanders...
I then see the ocean. Water. Dihydrogen monoxide. H2O. The most dangerous chemical on Earth (floods and such take more lives than any other natural disaster).
The Earth has a lot of it. The average depth of the oceans is about four kilometers. If the Earth's surface where a little less dimpled, we would all be under thousands of meters of water. Having lots of water is not unique to the Earth in the solar system. But having water in all three forms -- solid, liquid and gas -- on the surface, is.
"Water, water everywhere" is true in one sense. Hydrogen makes up 75% of the matter in the universe. Helium, a "noble" non-reactive, chemically boring gas, makes up 23% of the universe. The remaining 2% is everything else. Oxygen is number three on the hit parade at 1%, taking half of what is left, and carbon is number four at 0.5%, again taking half of what is left. Hydrogen compounds are everywhere. The simplest hydride of oxygen is water. H2O. So it should be no surprise that there is a lot of it about.
Water is both an acid and a base at the same time. The universal solvent. Real chemistry needs a solvent because most chemistry of note requires a liquid where the atoms are close together, but can move freely, get cozy with each other, and then move on. Water was required to create most of the minerals that today make up both the crust of the Earth and our bodies. Most of the Earth's hydrogen is bound up in water. Oxygen reacts strongly with almost everything (just ask the astronauts who lost their lives on Apollo 1) and is big part of the crust of the planet. If not for life on Earth, there would be no oxygen in the atmosphere today. The Earth would have "rusted" it all out. In a feedback loop, life created oxygen, which created new minerals, which created more new life and so on. Most of the Earth's crust came from life, directly or indirectly. And that needs water. In that sense, there is truth to the idea of a living planet (aka Gaia).
Water has a few more unique properties. Have you ever noticed that ice floats? Of course you have. But why? As a general rule, gases are less dense then liquids, and liquids are less dense than solids. Most solids sink in the molten version of themselves. But not water. And that is a damn good thing. It is a result of the dipole nature of the water molecule. As it solidifies, the dipole molecules line up in such a way as to decrease density slightly (about 9%). If ice sank, here is what would happen. Some ice would form in winter. It then sinks into the colder and colder water where it will never melt. Slowly, the water column would fill with ice from the bottom up. And finally all the water on Earth would be solid (a snowball world). The Earth would be white as a cue ball and highly reflective. New incoming solar radiation would be reflected back into space, keeping the Earth frozen forever.
Water creates snowflakes and rime and other crystals. Delicate little displays of fantastic mathematical symmetries. Fabulously beautiful.
Water in space is creepy. What would happen if you hand-wrung a water-soaked towel on the Space Station? The water would simply move from the inside of the towel to the outside. Now you have a cylinder of water between you hands, with a towel going down the center. But it gets weirder. Due largely to surface tension, the water would spontaneously start creeping up (or down?) your arms. Shades of "The Blob".
To a chemist, water is strange. It bucks a lot of trends. Its boiling and freezing points are much higher than other similar hydrides like hydrogen sulfide, which boils at -62 degrees C. Water's boiling point "should" be lower still. water 's Heat of Vaporization is also exceptionally high (this makes it ideal for steam engines). Ditto water's surface tension and cohesion. These properties result in rain, rather than what I would imagine as a choking falling mist. All these properties make water act like water.
Where did all the water come from? There was none on the hot primordial Earth. We are not 100% sure, but a lot probably came from comets containing cubic miles of the stuff impacting the Earth. And just a few hundred millions years later, life and water was all over the place.
Water is everywhere. On planets, and in nebulae (giant gas clouds), comets, and other cold objects between the stars.
After the sun sets, the stars come out. Perhaps you can see Andromeda, the remotest naked eye object and our twin galaxy, two million light years away? You will need good eyes and dark skies, and you will need to be north of the equator. Whole civilizations could have risen and fallen multiple times in the 2 million year transit time of the light. What would a civilization that is one million years old look like? But I digress...
Where was I? Oh yeah. Yep… the sunset sure is purdee.
Full disclosure: OK, I had to look up the boiling point of H2S and the percentages for carbon and oxygen in the universe, so it is unlikely that those numerical values would have been featured in my spontaneous daydream.
Krauss is an excellent writer, akin to Carl Sagan, and has a bent for philosophy. The book, as the title implies, is the history of big ideas… all physics of course ("god" is actually a very small idea).
The book is sprinkled with anecdotes about people who do not think like you and I.
E.g.: Paul Dirac (a mathematical genius who has his own formula named after him) was giving a lecture involving a lot of math. A student stated "Sir… I do not understand what you did between steps 12 and 13." Half a minute went by. Another student asked Dirac "Sir, are you going to answer his question?" Dirac replied "What question?"
Faraday was asked what all his electrical experiments were good for by Gladstone, the future PM of England. He is reputed to have replied "Well, sir, there is a good chance that in the near future you will be able to tax it."
The book has virtually no math in it, and is relatively easy to follow, up until it isn't. Even though I know the nomenclature fairly well, I get lost in the sea of particles (as did many physicists in the 60's).
Physicists have, throughout history, been dragged kicking and screaming toward their conclusions. Each step was thought almost ridiculous. There is a speed limit in the universe! Absurd! The "two-slit experiment" tells us of a ghostly world of weird interactions, and that weirdness is the foundation of our modern world.
Here is my encapsulated version:
If you want a nice overview of the progress and challenges of modern physics to date, this is a terrific place to start.
The physics of the last 60 years (my lifetime) have illuminated the world in ways that we cannot imagine (OK, I read the book and I cannot imagine). Near the end of the book, I confess I got lost, like the physicists of the 20th century, in a sea of particles.
The final chapter talks of great things: CERN, SLAC (Stanford Linear Accelerator) and LIGO (Laser Interferometry Gravitational Observatory) are some of the biggest, most expensive, machines ever built.
True monuments to the power of the human mind and utter weirdness of the world we live in. If it were not for cell phones and other forms of modern magic, I would think it all bullshit.
If you want a nice overview of the progress and challenges of modern physics to date, this is a terrific place to start.
Left and right are perfectly common words, with obvious meanings, right? Wrong.
Look up “left” in the dictionary, and it will say something like: Face north; your left arm is the one to the West. This just displaces the definition from “left” to “north”. Not very helpful. If you are standing next to someone when they ask “Which side is ‘left?”, it is easy. All you need do is point. Or point out that their heart is on the left side of their body. Easy to understand, but flawed because it is referring to shared objects that are familiar to both speaker and listener.
Describing left versus right to someone on the phone is pretty easy. You might say “Look at a clock. Nine o’clock is on the left. But again, you cheated. Effectively, you have just "pointed" again by referring to an object you both understand.
What if there are no shared objects?
Now suppose you are talking to an alien on the other side of the universe. You gave agreed on and defined hundreds of words until you get to “left”. Is it possible to tell that alien which side is “left”? You might say “Sure! I will send a bitmap picture of something and point out that this or that bit of the image is on the left. But how did they get the bit-map? They had to print it out in some sense, and when they do, they have to decide whether to print from the left to right or right to left. If they pick wrong, their “left” and yours will not be the same, and the image they look at will be a mirror image.
It turns out that it cannot be done… at least not by mere mortals like you or I.
Physics and biology are full of left and right hand rules. If you point your right thumb up (north) and curl your fingers, you have just used the right hand rule to determine, for example, the direction of the Earth’s rotation (counter-clockwise), or the direction of a magnet field around a conductor (where thumb points in the direction of the current), or the direction of the spiral in DNA.
Left and right are important. If you only have one hand, and you want a glove, for example. (Fun fact: If you invert a left hand glove, you get a right hand glove.) Simple sugar comes in two versions: a left-handed isomer and right-handed isomer. In our bodies, and all other critter’s bodies, we all use just the one isomer and ignore the other. Once biology made its choice, it was stuck with it.
The labels of left and right are (almost) completely arbitrary. If we were to redefine right as left and vise versa, some interesting things must happen, including relabeling the poles of a magnet (north becomes south), and redefining “clock-wise” too.
If you were to look down on a game of pool, there would be no way to tell if you were looking at the real image, or a mirror image. The balls would ricochet about as usual regardless. A mirror image universe would be almost indistinguishable from our own. Almost…
Physicists often speak of CPT conservation. The C is for charge. Charge is always conserved. The T is for time, and says that the laws of physics are the same regardless of whether you run time forward or backward. The P is for Parity, and it essentially says that laws of physics are the same for a mirror interaction. However, a few decades ago, it was discovered that P is not conserved and that some physical interactions differ from their mirror images!
That is weird.
The universe cares about the difference between left and right. It turns out that Parity is not always conserved ( see the Wu Experiment for more). So, as I said, for us mere mortals, telling an alien race on the other side of the universe what direction left is is not possible.
But if you are a physicist, you could tell the aliens to “go like this, then do that, and you will see such and such, you will find that certain things tend to go one way rather than the other, and that direction is ‘left’ and the opposite ‘right’.” To do the experiments involved, you will need a particle accelerator. When the results were announced that Parity was not always conserved, physicists reviewed older experiment data and discovered that the pattern was there all along, but the result was so unexpected, no one thought to look at it.
Expectation bias strikes again!
It's about time. Or more aptly, it's about cultural speculation on the nature of time and time travel.
I do not have a lot to say about this book. It is well written and very well researched. There is a lot of material to cover. Here are just a few of the items discussed:
The usual brief discussions of the speed of light and the Second Law of Thermodynamics (i.e.: You cannot stir things apart) are there. It is generally the Second Law that gets in the way of time travel (another is causality problems). The universe began in an extremely ordered, low-entropy state. How it got that way is unknown. But once things got started (the big bang), entropy began to increase. Entropy is essentially the amount of disorder in a system. One possible end for the universe is the so-called heat-death: the universe expands endlessly; stars die; the matter in stars ultimately decays; and all we are left with is a thin gruel of electrons and positrons orbiting each other with an orbital diameter the size of the universe today. Would time still exist? There would be no events to mark its passage, so it is hard to say.
It is a fact of physics that if there arrow of time were suddenly reversed, no laws physical would be broken. At the atomic level, you would not be able to tell that time was running backwards. But at the human level, it would be obvious, as you watch your pee magically pull itself out of the toilet water and spontaneously shoot itself back into your body.
Time travel has implications about free will that are summarized.
The book is light on physics, but gets the physics right.
It does not: Tell you how to build a time machine; tell what time really is (other than the usual quips, such as "time is needed to keep everything from happening at once"; or resolve the causality paradoxes involved (e.g.: Go back in time and kill your grandmother… what happens?).
Gleick has written a few science books, including his very good biography on Richard Feynman.
ATC, I liked Hawking's A Brief History of Time, although, to be fair, they are not really comparable.
As Douglas Adams has famously pointed out, the universe is big. Really, very, incredibly, biggly. This is common knowledge today, but we only learned this fact about 100 years ago. We named the coolest scientific instrument ever invented after the discoverer: Hubble. We actually have no idea how big the universe is. It could go on forever. The universe we can see is at least 25 billion light years across. Even though the universe might be finite in size, fear not, there is no chance of falling off the edge. Just like the spherical Earth, there is no edge. This idea of “the ends of the Earth” edge persisted despite the fact the Greeks knew the Earth was roughly spherical since about 300 BC.
Light is the universal speed limit. Practically all of physics relies on this fact. Certainly the physics of the very large (big stars and stuff) and the very small (atoms) are peppered with references to “c”, the symbol for that speed. (It is a curious fact that the speed of light has almost no influence at our scale. About the only time you might be aware of it is during live satellite communications due to the substantial distances involved.)
For the record, that speed is 300,000,000 meters per second. Very large distances are often measured using the time it would take for light to make the journey. Hence the previously mentioned “light-year”. There is absolutely no reason to believe that this speed can ever be exceeded. UFO fans often believe otherwise. They are misinformed. Kip Thorne (who just won the Nobel for physics), in his book Time Warps and Black Holes, speculates on how the cosmic speed limit might be beaten. It usually involves getting from point A to point B without going through the intervening space. He speculates that this might be possible, but his speculations rest on fantastically exotic and largely hypothetical forms of matter and energy. To master such forces would require machinery built on a god-like scale. I discount these fanciful ideas for the same reason that I do not believe in god.
While the actual universe is fantastically large, our bit of it is relatively small. We live in the Milky Way galaxy. The nearest galaxy to us is around two million light years away. Two million years is much longer than the time homo Sapiens have even been talking to each other (about 40 times larger). It is hard to imagine us ever talking to beings in another galaxy, the distances being so huge. Just to “hello” and get an answer would take 4 million years. Ordering Andromeda take-out is out of the question.
Our galaxy is still pretty big though. One hundred thousand (100,000) light years across and includes 100 billion plus stars. This is still a daunting size. The fastest object we have ever launched—Voyager— is moving at around 60,000 km/h. This is only one 18,000th of the speed of light. The nearest exo-planet to the Earth that we know of is about 10 light-years away, making it about 180,000 years away at Voyager speed. Of course, we could launch faster vehicles if we want, but it isn’t cheap and we would need a good reason to do so.
It is a classic first year physics problem to calculate the energy required to move a man on a spaceship from a standing start near Earth to close orbit around the nearest star. The trip must be at one gee all the way, thus making for a comfortable ride for the astronaut. One gee of acceleration for the first half of the trip and one gee of deceleration to come to a stop near the target star. One Earth gravity, or one gee, means going about 10 meters per second faster, for every second. After just one day, the ship will be going more than 900 km per second… much faster than Voyager. Making ridiculously generous additional assumptions (infinite supply of weightless fuel, weightless engines and so on) it would still take all the power mankind can master, or ever has mustered to pull this trip off. In other words, if we add up all the wood, coal, oil, A-bombs, hydro, nuclear reactors, etc ever used throughout history, it would still not be enough energy to do the job. And when we get there, we would probably find nothing.
The upshot of all this is that if we ever expect to find company in the universe, we had better use light (or rather, radio waves) moving at the fastest speed there is, but even then, the conversation will be excruciatingly slow.
How far away could the hypothetical exo-civilization be in theory? It depends. If the conversation were one way only, it could be quite far away. As long as the signal from the other civilization was bright enough, we could listen in. If the other civilization’s “ears” were really, really sensitive, they might be able to listen in on us. But how about chit-chat with a civilization just like ours? I did a back-of-envelope calculation on this subject. It involves a unit of electromagnetic flux called a Jansky. If the other civilization’s “ears” (actually huge radio telescopes) are equivalent to ours, they would have to be within about 400 light years of Earth for us to both chit and chat. This is essentially our back yard…. less than 1% across the galaxy. IMHO, it is unlikely that this relatively small bunch of stars and planets contain such a civilization. We have recently discovered that many stars have planets. We always suspected as much but confirmation has only come in the last few years. That is the good news. The bad news is that it is becoming more and more apparent that planets come in many shapes and sizes… and most of them are nasty. The Earth’s characteristics, like being in the Goldilocks zone (see below), are rare. How rare we do not know yet. Even being in the zone is no guarantee. Venus is much like Earth, and in the zone, and it is a hell hole.
Aside: The “Goldilocks zone” is the distance from the star one should be to allow for water to be in all three forms on a planet: liquid, gas and solid. It is just one of many criteria that are thought to be necessary for life.
If we were to find a civilization similar to ours inside this sphere, it would be truly amazing. The conversation would be slow, and perilous: we cannot say if “they” are friendly. But the conversation would be possible, and we would know that we are not alone. In fact, if we found one that close to us, it would not be a huge leap to imagine a galaxy riddled with life and intelligence… a la Star Trek. I love the idea, but again, I suspect it unlikely.
So get used to loneliness. The universe may be crowded. In fact, I think it must be. Even at one civilization per galaxy, we have a universe with billions of intelligent species. But our ability to talk with them is constrained by the cosmic speed limit, and those constraints make it unlikely that we will find a sister civilization anytime soon. Another curious fact is that the cosmic speed limit actually opens the door to sight-seeing the universe because of something called “time dilation”. But that is another topic.
Carl Sagan had it right. Our Pale Blue Dot is it. We can toodle about the Solar System all we want, and no doubt we will, but our only home is on the Earth, and if we want to be here for a while longer, we had better take care of it.
The Earth has been in a nearly circular orbit around the sun for billions of years. Each year, our planet carves out an ellipse with the Sun nearly at the center. That circle define a mathematical plane called the “plane of the ecliptic”.
The Earth also spins on its axis once a day. The Earth’s huge angular momentum keeps the axis of the Earth’s rotation pointing in the same direction – towards Polaris in the north -- exactly like an enormous gyroscope. (Actually, the axis itself wobbles over a period of 41,000 of years. In a few thousand years, Polaris will no longer be the “pole star”. )
This has been a banner year for exploration of our solar system, and it starts me thinking about our Earth and its unique characteristics. So WTF is 23.4? It is the angle that the Earth’s axis of rotation makes with the axis of the plane of the Earth’s orbit, called the “obliquity of the ecliptic”… 23.4 degrees. This number has had a huge impact on us, and we would not be here to talk about it if it were dramatically different from that value.
Take a look at any decent globe of the Earth. They are all mounted on a stand that tips the Earth 23.4 degrees. The Arctic and Antarctic circles are the northern and southern-most latitudes where the sun disappears completely for at least one day. The Tropics of Cancer and Capricorn are the northern and southern-most latitudes at which the sun appears directly overhead (at noon of course) for at least one day of the year. The Tropics are 23.4 four degrees off the equator. And the Arctic and Antarctic circles are 23.4 degrees of the poles.
What would happen if this number – 23.4 degrees – were much different? How would the Earth be different? What if it were zero, or 90 degrees?
At zero degrees, the Earth’s weather would be much different. There would be no seasons. I suspect that the Earth would probably have bands of weather similar to those on Jupiter. The seasons have large consequences on evolution and it is certain those changes would affect us. Uranus is at 82 degrees, but is so far from the sun that it doesn’t make a lot of difference to its weather. Pluto is at 57 degrees. Jupiter’s is close to zero.
Aside: We would generally expect the planets to have near zero obliquity unless an event knocked the planet off kilter. This is because most of the material that accreted into the planets would also have had momentum that must be conserved… and that momentum was generally circular about the sun in the plain of the ecliptic. In the case of the Earth, it was a huge impact with a Mars-sized object that tipped the planet axis of rotation, and created our moon. Because the moon is so large compared to the Earth, the Earth-Moon system is actually a double planet and the only one in the solar system.
At ninety degrees, things on Earth would be much worse. For large parts of the year, the north and south poles would alternate between never ending sunshine and heat for half the year, and absolute darkness and cold for the other half (I assume no moon). At the equinoxes, and if you lived on the equator, you would see a sort of normal day, with a rising and setting sun. However, life on Earth would be very different from what we know.
There is nothing special about the number 23.4 degrees (as I said, it actually changes over the years) but it does seem to strike a happy median between the two extremes of zero and ninety degrees. It dictates where and when the sun and stars will rise and set and their path through the evening sky. It has a profound effect on the history of human kind, both from an evolutionary perspective and from a historical one. The first priests were priests because they were to first to codify the drum-beat of the seasons. And civilization started with agriculture.
Lee Moller is a life-long skeptic and atheist and the author of The God Con.