Saturday, 18 January 2020

How well can connected boxes learn to swim? The ecosystem game

Sometimes I play a computer game, mostly of the simulation type. While looking for something different from steering a European nation through history, or building a sprawling city somewhere, I came across a game promising to show biological evolution.

It would not be the first time a game tried to do that; Spore promised that too, and there are some others. I even wrote a post about Spore for this blog, because I was curious how the game designers dealt with the number of legs a creature might have. That number did not evolve by itself, but was chosen by the player. While the anatomy and movement of these legs were cleverly arranged, they turned out to be completely predetermined. In other words, the gradual changes in shape and capabilities of the resulting beasties had nothing to do with random variability followed by the environment pruning the stragglers, which is how real biological evolution works. Instead, Spore relied on Intelligent Design by the developers, and to a lesser extent by the player, acting as a minor deity.  

Click to enlarge; copyright Tom Johnson
But this ecosystem game promises the opposite. You get to play with a barren stretch of sea floor and have to turn it into a thriving ecosystem. The game will create swimming animals completely on its own, at first anyway. There is random genetic variability, and the unfit are weeded out, leaving their more successful brethren to forge on. You may wonder whether a full evolution simulation handled in this way would be any fun to play. After all, the premise would firstly be that genetic, anatomic and functional variability are all left to chance, and secondly that the environment provides all the selection pressures. What is left for the player to do?

In the demo, the player can indeed not control the characteristics of the beasts at all, but can guide evolution by altering the environment. The player has to place new plants or simple animals as food, and will also have to provide spawning areas and cordon off some pleasant mating grounds. Then you watch to see whether your Chosen Species rises to your challenge.

In the final game, there will also be a possibility to tinker with the anatomy of the beasts directly. An example of how that may look is shown above. Much as I like the idea of a fully independent evolution model, I also look forward to take up my duties as Minor Deity and start tinkering. In the full game you do not need content yourself with one Chosen Species; there will be various species, and herbivores as well as predators. At present, the game is in an early stage, so do not think you can lord it over a complex ecosystem just yet. That will be later. But a large part of the true evolutionary part is already in place. Let’s discuss the mechanics and the nervous systems of these beasts.

Tom Johnson, the creator of the game, provided some explanations. The animals consist of connected rectangular boxes of varying width, length and breadth. That’s it: they are boxes. That is what is shown in the video above. In the game, the animals look much nicer, as the boxes are depicted as smoothed forms with some nice fishy textures. At one end of one box there is supposed to be a mouth. To help the player, this part is shown as having a distinctively fishy head, with two eyes and two jaws. In a way this is a pity, as otherwise the animals have nothing that reminds you of a vertebrate. They are wholly and spectacularly asymmetrical! The boxes move at the connecting points, sometimes around one axis, sometimes around more than one. If one box moves with respect to another, this creates forces acting on the water around our hopeful monster. There is drag, there is angular momentum, and the creatures moves. Well, if you play the demo you will find that the earliest forms flop rather than swim and can be so painfully clumsy that they die before they even make it to any food.

The animals have nervous systems with an input layer, a layer for connection and integrationr (the Brain!) and a layer of output neurons controlling the muscles of each body part, which is, unsurprisingly, a box. You can actually see the neuronal connections in action, with impulses speeding along the axons (although at present the number of visible impulses does not reflect the true impulse frequency yet – for that you have to look at the number next to the neuron-). In successive generations, both the anatomy of the boxes and their nervous systems evolve. It is not quite clear to me yet whether the neural system develops at random or in response to mechanical needs. At any rate, I think it is an impressive feat to have both an evolving anatomy as well as an evolving brain linked to that anatomy.

Tom told me that the capacity of the evolutionary fitness principle was well born out by the game. At one point it turned out that some features of the animal worked only with a specific frame rate. In other words, the modelled animals had taken full advantage of one characteristic of their particular world, even though that was a completely unintentional one.

Another example is the animation above this paragraph: the animal seems to wave one limb in such a way that it acts as sort of propeller. In my searches for original means of locomotion to use on Furaha, I had tried to find a way to have a limb do just that. The problem is of course that in biology you cannot have a body part going through a complete 360 degree turn, as that would of be incompatible with blood vessels, nerves and muscles running to that limb. I could not see well enough how the movement worked, so I asked Tom. His reply was that I needn’t bother, as that was an early design, and he had not specifically stopped the animals from having continuous circular motions. So, again, blind evolution had used what it could and found a way...

Tom was kind enough to send me a unique illustration for this blog, shown above. The wrote: "This creature lives in the deep sea with a rocky, spiked terrain and evolved a nice downward glide to stick to the seafloor and eat the sessile creatures attached to it." I like it.

As I said, at present this game is available as a free demo, here or here. I will be keeping my eye on it, to see what strange forms can and will evolve. Charles Darwin once wrote the following about evolution:

 “There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.”

Isn’t it fascinating that we can now see these principles in action, right before our eyes, on our computer screens?

Wednesday, 13 November 2019

Work in progress: the prigoon again

Lately, I have been wondering whether it is really a good idea to keep the paintings hidden until the publication of the eventual book. If I do not show the paintings, then I should probably keep interest going by writing posts more often. But the kind of posts I write, with literature searches and illustrations made to order, take a lot of time.

Perhaps I should write some shorter posts instead, just short ones, without much depth. Let me known what you think of such an approach.

Click to enlarge; copyright Gert van Dijk
 To try it out, here is a work in progress: I have worked on the prigoon's head and back shield. I like painting textures, and thought I should try my hand at iridescence.  The legs need to be detailed, but that is fairly boring work. After that I wil work on the shdows some more, because the animal is a bit flat right now. At the very end I will probably use blurring to create the idea of macro photography.

Monday, 21 October 2019

The prigoon: a secondary bilateral spidrid

I cannot imagine that anyone will remember that I wrote about animals that walk on five legs in this blog. Actually, I hardly did, and that is not surprising as it was almost exactly 10 years ago. Well, I did remember that I wrote about 'odd walkers', but had forgotten that I had actually produced an animation for an animal with two pairs of legs and an unpaired one.

So why bring this up? Because I am working on a painting of a 'secondary lateralised spidrid'. It's a small exoskeletal predator. Think of a jumping spider on Earth. The animal is descended from radially symmetrical spidrids, and during its evolution the new plane of symmetry somehow came to run through two opposite pairs, rather than between them. Mind you, these exist too, but for unknown reasons the latter group is almost exclusively herbivorous, while the ones with one jumping leg are mostly predators.

Click to enlarge; copyright Gert van Dijk
So here is a colour sketch. I think I will call it a 'prigoon', but I haven't thought of its binomen yet. The name will probably contain 'dougalii'  or 'dixoni', as Dougal Dixon was the first to come up with this odd arrangement, and I wouldn't want people to think I am quoting anything without a proper reference.     

Wednesday, 17 July 2019

Slowing down before speeding up again

I haven't written a post for a long time, and neither have I produced many new paintings for The Book. There are two reasons for that; I will explain both, and will show some sketches of what is going on.

The first reason was that I was facing two complicated concepts. The Book at that point counted over 100 pages, meaning over 50 full paintings, not counting maps, scale drawings and additional smaller illustrations. I had kept the work on hexapods for last. Hexapods largely take the position of terrestrial vertebrates on Earth. They also represent a similar degree of adaptive radiation, so there are burrowing animals, animals analogue to amphibians, predators, brachiators, and much else. Some returned to the sea, and there is at least one group, but probably two, that have learned to fly. I had aimed to devote at least 15 full paintings to hexapods, keeping them for last. I actually have quite a few oil paintings of hexapods that I could simply paint again, now digitally, and most importantly better. But I was no longer satisfied with two important design considerations: their jaws and legs.

As for their jaws, until now the idea was that hexapod ancestors had six jaws, placed radially around their mouths, with one row of teeth each. I envisaged that the two upper ones would meet at the end and connect, forming an arc in very much the same way as our mandibles form an arc. The two lower jaws would do the same, resulting in four jaws: both the one at the top and the one at the bottom form arcs, and the lateral ones would bear one row of teeth. This provided much design freedom, so the lateral jaws, or an upper or a lower arc, could grow into ploughs or whatever instrument might be useful.
   But over time I became dissatisfied with this design, as I wanted something that would work but would be stranger than the earlier design that looked too terrestrial. My attention was drawn by 'linkage systems'. These are the complex assemblies of often more than for bones that allow fish' mouth to suddenly telescope outwards to double their length, and do other interesting things. I have used linkage systems before; the rusp snout is a design I like. Now, Earth fish are obviously bilaterally symmetrical, so designing a linkage system for fish more or less involves movement in a vertical plane lying parallel to the longitudinal axis of the body. Thinking of linkage systems in two dimensions is not that hard. You turn them onto a three-dimensional mouth by connecting the frontal ends from the left and right sides.
   Furahan hexapods are also bilaterally symmetrical, but their mouths started out as a radial design (here and here). How about a radial linkage system? Now that is a challenge: do adjacent jaws slide along one another to provide cutting surfaces? Or do they simply point inwards, with pointy teeth on their ends? How do adjacent jaws link up to provide an extended reach and yet allow a forceful bite? This requires some serious though and probably tinkering with diagrams and possibly bits of cardboard or wood; what it takes is time...

With six legs, may gaits become possible. That is not the problem. But I certainly did not want to fall into the trap that I complained about before (one, two, three and four): many artists having to draw six- or eight-legged animals simply copied the hind legs as often as needed. In many cases those doubled hind legs moved in unison, making the whole assembly superfluous. One way to avoid that would be to come up with a different gait, which is not difficult, as I explained before.
  But there is another problem, and that is the anatomy of these legs. It makes sense to design legs for big animals in such a way that the segments bend in alternate direction: if the topmost one points backwards, then the next one down should point forwards, etc. (see here and here). This results in a zigzagzig pattern, and if the top one points forwards, you get a zagzigzag pattern (see here and here). With two pairs of legs, one can be zigzagzig and the other zagzigzag, or both can be zigzagzig (or zagzigzag). But with three pairs of legs there is a challenge of how to avoid repetition. So I played with joints that point forwards while the leg moves backwards and that still point backwards while the leg moves backwards. I haven't made proper animations yet, but the sketches reveal that the result certainly looks odd. The problem is that the joints would have very large ranges of motion, which cannot be good for stability. At present I think the best solution may be to apply one pattern for all pairs of legs, such as zigzagzig (or zagzigzag). I will need to do some serious animation studies to come up with the best design. Again, that takes time...

The time did not seem to be a big problem; I had already decided to reduce my working hours by about one third to about 36 hours a week, which would free the time to do this, make animations and more besides.

But something came up. I had been living on my own for a long time, being a widower. But I unexpectedly met someone who is now very dear to me; as I am sure most readers will know from experience, time spent on a relationship is not only time spent well, but also spent lovingly. So to my surprise I found my newly liberated time taken up by a very positive development. Where does this leave The Book? Well, the answer is that it will require another realignment of priorities. And the only thing that is a suitable candidate for reduction is work, so there will be less of work and more of other things.

Some appetizers
I was not all lazy meanwhile! I just finished one painting and another one will be finished shortly. The Book will contain at least two examples of the official portraits of dignitaries and luminaries who are honoured by having their portraits in the halls of the Academy and the Gallery of the Institute of Furahan Biology. These people are Grover P. Uytterwaerde, the third Rector Praeses of the Furahan University, and Profissima Tartufa S. Rulyinka. Actually, one of the first posts in this blog already showed a sketch of such a portrait.

Click to enlarge; copyright Gert van Dijk
The other painting shows rusps, this time of the microrusp variety. While I was gathering courage to tackle the hexapod 'jaw and leg' problems, I thought I could fill the time with rusps. In this case, I took the 'flexible evolution of limbs' that is also apparent in another post a bit further. Instead of reducing some limbs at the front of the animal, why not do away with some in the middle? That would provide a supple anatomy. The 3D sketch above was done in ZBrush, done mostly to work out the shape of the head (rusps heads are complex). I did not bother modelling the legs as it is easier to just draw them.

Click to enlarge; copyright Gert van Dijk
Here is a sketch of an entire animal, legs and all. Fully grown ones are about the size of a fox.

Click to enlarge; copyright Gert van Dijk
And this is the beginning of a painting showing these microrusps. The setting is dawn in a dry environment. A group of these animals, called 'baloors', are having their first look at what the day may bring.          

Click to enlarge; copyright Gert van Dijk

No 'Gigafiffyfees'
Here are sketches of a species that will not make it to The Book. I took the Fishes IV design, and thought they might ebolve into giant filter feeders. To that end the upper and lower jaw arcs would envelop the much altered lateral jaws that contain the filtering apparatus. The tips of the upper and lower jaws can be closed to stop filtering and so reduce drag. With the tips open, water would flow through the filter continually, flowing out through outlets at the corners of the upper and lateral jaws. These animals are hexapods, and their hind legs have formed flippers much like whales' tails.

Click to enlarge; copyright Gert van Dijk
I even started a painting of an altered design, in which the lateral jaws envelop the upper and lower ones. As these are 'giant filter feeder fish', they became 'gigafiffyfish'. No, I do not know why; perhaps some zoologist's toddler could not say 'giant filter feeder fish' and the garbled result was adopted as the animals' name. If this is not true, it is still a good story. Anyway, in the end I decided against them: even though they make sense, they are too much like Earth whales.     

So that's why I've not shown much new material. But the outlook for more material is very bright.  

Monday, 1 April 2019

Extraterrestrial life after the Drake and Seager Equations: the 'Nastrazzurro Equation'! (the what?)

In previous posts I discussed the Drake Equation (DEq) and the Seager Equation (SEq), and promised to expand those by presenting my own version, the Nastrazzurro Equation (NEq). Let's start with a quick refresher of the DEq and SEq. Both provide estimates regarding extraterrestrial life, but in different ways.

Frank Drake aimed to estimate the number of intelligent civilizations. Actually, the DEq was aimed at just one particular subset of alien intelligences, meaning those that we should be able to detect on Earth because the aliens in question live nearby and obligingly send out electromagnetic signals into space in very much the same way that we do. Quite a bit of effort is spent listening to the stars to find out whether anyone out there is actually doing that. Writing my post on the DEq strongly influenced my opinion on the matter: I do not expect this method to produce any exciting news anytime soon. The numbers seem to be against it: electromagnetic signals decrease with the square of the distance, so they become very weak even over short distances; short in the astronomical sense, that is. To detect such signals with our current equipment the strength of the signal would have to be ludicrously strong, making you wonder why anyone would want to do so. You may also wonder how long a civilization will keep on transmitting, which is an important factor in the DEq. Apart from the question how long civilizations last in the first place, there is added problem that sending out electromagnetic signals into all directions at once, as we do, seems a bit silly. If the message is meant for people on your own planet or in your own solar system, surely an advanced civilization can somehow direct the signal to where it should go.

Sarah Seagers' approach is quite different. Her primary aim is not aim to detect signs of intelligence. Instead, she wishes to study the composition of a planet's atmosphere by seeing how that atmosphere changes the light of the planet's star when it shines through it. If the atmosphere alters the star's light in a way that suggests metabolic processes, than life is the easiest way of explaining their presence. In other words, does the atmosphere host a biosphere? Just as people are trying to obtain factual evidence of alien radio signals, there will be factual efforts to seek for biospheres in this way. The 'Transiting Exoplanet Survey Satellite' (TESS) was launched in 2018, and will probably find lots of potential planets to investigate later. That 'later' means scrutiny by the James Webb space telescope, not yet launched. Here is some more information on that telescope from NASA. By the way, NASA asked artists and the general public to produce art for the occasion; one of the results is the poster above (here is a link to the art section). The James Webb telescope will apparently launch in 2021, so we might have an answer to the question 'Is there life out there?' within 10 years. National Geographic has some nice information on the search for extraterrestrial life and the methods to find out, right here.
Astronaut Bowman looking at the monolith. "Oh my god, it's full of stars!"
The current count of exoplanets is about 4000. That is impressive. Not so long ago the presence of planets outside our own solar system was completely hypothetical, and by now we have become accustomed to the idea that the universe is full of planets. I still find it exciting that that hypothesis is now a fact, but finding life -LIFE!- outside Earth would be news of a much larger magnitude. I doubt that life is as ubiquitous as planets are, but learning that there are planets with life should make people think a bit more about life on Earth. Perhaps they will become a bit more respectful of it (they had better). Finding proof of alien life would make me feel like astronaut Bowman in the book 2001, or the film 2010. He looked into the monolith drifting in space and exclaimed: 'Oh my god, it's full of stars!' Perhaps 20 years from now we can look up and say 'Oh my god, it's full of life!'. I guess I'm a romantic at heart...

Anyway, back to the equations: both result in estimates of the number of either civilizations or biospheres that we can detect. And there's the rub: detection! The DEq and SEq aim to obtain factual evidence. And that is precisely the difference with the 'Nastrazzurro Equation' that I propose here. Let me make it clear that I see the NEq as a fanciful thought experiment in science fiction; it is not a competitor of the serious DEq and SEq. If there would be a diminutive of 'Equation', I would use it (it might be 'equationicula', but that sounds as silly as 'equationette').     

So what does the somewhat arrogantly named 'Nastrazzurro Equation' actually do? Well, it utterly  and completely ignores any wish for actual evidence. That makes it science fiction. Of course, the whole subject of speculative biology is science fiction, even though I like my science 'well done' rather than 'rare'. I like films with alien intelligences in it, especially if these films also betray human intelligence, which is not a given. My main interest in all this is alien biology as a whole, and I can do without the intelligence. I would probably have preferred 'Avatar' to be a documentary rather than a drama. Actually, there is such a documentary, but it is only four minutes long.

The NEq deals with the question 'How many interesting biologies might there be out there?' At present, I will accept anything as 'interesting', such as a planet with microbial life only, although my interest might become less keen quickly. I would accept with unmoving spongy thingies on the sea floor, spending aeon after aeon doing a spot of quiet filtering. I would love things that jump, move and fly, but for now, any life will do. So: how much life could be out there?

Click to enlarge. Screen shot from this website
Actually, you can use the Drake and Seager equations to answer that question! For instance, take the Drake equation; rather than doing the actual hard work ourselves, let's use the nice program to do the calculations I used before, found here. The image above shows how it works: there are successive boxes in which you can fill in estimates.
  • First, choose an overall setting such as "today's optimistic" and proceed. 
  • We can leave the first four estimates as they are. 
  • The fifth box asks for the percentage chance that life develops intelligence. We do not care about intelligence and we do not want that box to reduce the estimate, so we simply put in 100 (If we were to use a proper equation, this term would be left out). 
  • The next box asks about the percentage chance that life can communicate across space, and we do not want that one either, so we set that to 100% too. 
  • We then are asked to fill in the length of time that a civilization actually transmits signals. Here, we do have to fill in a number, but it should represent something else: it should be the length of time a planet harbours life. That's a tricky guess, but the number will certainly be much larger than the time a civilization is transmitting. But we can use actual data! Life has already existed on Earth for 3.7 billion years (3.7x10^9 years), and might exist until the conditions for life cease to exist, which might be in 2-3 billion years, according to Wikipedia. So we can put in 6x10^9 years as an estimate. Unfortunately, you will find that the programme does not accept such large numbers, so for now we just leave the setting at 10 million (10^7) instead of 6x10^9 and remember that the result will later have to be multiplied by 600. 
  • The last box asks for the number of times a civilisation can redevelop. Here, we will assume that life needs to evolve only once, so we set that to '0' instead of  '3'. 
  • Press calculate and get 18,900,000 planets with life in our galaxy, or, say, 1.9x10^7. 
We must not forget that the estimate of duration was 600 times too short, so our estimate becomes 11.4x10^9 planets with life in the galaxy. That is 11,400,000,000 planets. Nice! You will get other results, depending on the starting conditions, but the message is clear. But estimates need to be compared to something, so let's compare them to the number of starts in the galaxy. Here is a post by NASA from someone who tried to find out, and the result is 100 to 400 billion. Let's use a nice average of 250 billion, or 2.5x10^11. Our increasingly wobbly NEq tells us that that one in every 22 planets has life. Wow! 
Click to enlarge. From this website

How about the Seager equation? We can hijack that and turn it into a Nastrazzurro Equation too! Let's go for the "original Seager values".
  • The first box asks us about the number of 'observable red dwarfs'. We do not care about 'observable', and we will also allow for other types of stars. Again, we need an estimate for the number of stars in a galaxy, and we can take the 250 billion estimate again (2.5x10^11). The highest settings seems to be 500,000, so let's remember that our calculation will be 500,000 times too low. 
  • The next box asks for minimal disruptions. Let's leave it at the original 20%. 
  • The next box concerns the percentage that can be observed. We wish to ignore that, so put it at 100%.
  • Let's leave the estimate for 'rocky planets' as it is, at 15%. 
  • Let's set the percentage with life to a low value of 1% as per the original values. 
  • The next one is about detectability again, so that becomes 100% for 'omit this box'. 
  • We press calculate and get 15,000. 
That's not very much, but we still had to multiply the number by 500,000. So now we get 7.5x10^9 planets with life. That is one in about 33 planets. Still wow!

So this is the result of the official 'Nastrazzarro Equation' for the number of planets in our galaxy with life on it. It is a bit silly but not idiotic. After all, it is merely a simplified form of the Drake and Seager equations. It only contains one factor not present directly in the DEq and SEq and that is the number of stars in the galaxy. Here's an interesting twist: the NEq reduces the number of parameters in the DEq and SEq, and all these factors have a very large uncertainty. So, and I rather like pointing  out this somwewaht cheeky observation, by reducing the number of factors the Nastrazzurro Equation can be said to be more precise than its more serious predecessors. Well, perhaps 'less immensely uncertain' is probably a better term...

A megarusp; click to enlarge; copyright Gert van Dijk
What I like about all this is that The Nastrazzurro Equation suggests that there is room for something like a 'woolly haired shuffler' somewhere in the galaxy; there is room for rusps too, and spidrids, and, well, all of it. Not so bad for a thought experiment in speculative biology, is it?

Saturday, 3 November 2018

Equations II: The Seager Equation

Click to enlarge; composite of web photo with painting by Gert van Dijk

The Drake equation, discussed recently on this blog, provides an estimate of how many communicating civilisations there are in our galaxy. It does so by multiplying a series of factors; none of these is rock solid, so some say it is basically guesswork. That is true, but in the absence of hard facts an educated guess is the best evidence there is. The nice thing about the Drake equation is that it in essence falsifiable, meaning that it is, at least in theory, possible to say whether there are such civilizations or not. In theory, that is, because one of the two possibilities is that are no such civilizations, and it is usually much harder to prove the absence of something than its presence. If someone in another solar system one day decides to answer our interstellar call, for instance to ask mankind to please turn the volume down, or to stop pestering them with unwanted phone calls in the middle of dinner, then we will know for certain that there is someone out there. But at present we have not received any signal, which tell us precisely nothing. It is like fishing: as long as you haven't caught any fish, you cannot conclude there aren't any. Only when you've caught one can you say that there are fish (or, more precisely, that there was at least one fish; you may just have exterminated the species).

Habitable zones (from

Sara Seager, an astronomer at MIT, proposed a different approach. If you Google her you will find many entries, among them her own website. Her reasoning rests something much more basic then intelligent being using radio signals: is there a biosphere? Her idea starts with the concept that life requires liquid water, an concept that certainly holds water (sorry for that one). Liquid water requires a planet in the habitable zone at the right distance from its star. What I learned from an overview of the conditions under which you might get liquid water is that there might even be liquid water on runaway planets that are no longer circling a star. Anyway, take a planet, add life, stir and wait, and you might get a biosphere. It is wise to search for stars with a nice quiet long term behaviour, so the stars do not cook their planets halfway down the line. Lifeforms have metabolisms, and spew out interesting gases that provide a 'biosignature' in the atmosphere around an alien planet.

Life on Earth certainly altered the atmosphere. At one point there was a nice community of anaerobic organisms quietly doing their thing, and then some new-fangled intruders called 'plants' starting using a highly polluting process called photosynthesis, with a highly reactive dangerous poison as a by-product: oxygen. Plants may have caused the very first mass extinction. Later on, animals learned to control how to burn stuff slowly with that oxygen, making a dent in the amount of oxygen, but not a large one, so Earth's atmosphere now still consists of 20% oxygen. And that can be measured from afar.

Click to enlarge; principle of spectroscopy on transit signal
Unfortunately, the detection is not easy. The method Seager proposes rests on planets passing exactly through the line of sight from Earth to the planet's star, so they appear to transit the disk of that star. That process works well and has already resulted in the discovery of many exoplanets. The TESS satellite was launched in April of 2018 to find many more. When the planets pass the star, they alter the composition of the star's light, and that change tells you something about the planetary atmosphere. Of course, not all planets happen to pass through that line of sight, so only some are observable this way. There is another problem: many biosignature gases are destroyed by ultraviolet radiation from the star, reducing their amount. These gases will be easier to detect if they are not broken down by UV, which is why Seager proposes looking at M-type stars (red dwarfs), because that live long and put out little UV. The latter job is to be done by the James Webb satellite, to be launched in 2021 (probably).    

Here is the Seager Equation:


* N is the number of planets with detectable biosignature gases
* N* is the number of stars within the sample
* FQ is the fraction of quiet stars
* FHZ is the fraction with rocky planets in the habitable zone
* FO is the fraction of observable systems
* FL is the fraction with life
* FS is the fraction with detectable spectroscopic signatures

If you study the parameters, you will see that several factors have to do with the 'detectability' of a biosphere. That holds for the fractions that concern 'quiet stars', 'observable systems' and detectable 'spectroscopic signatures'. Those fractions decrease the total number appreciably.

Click to enlarge; from:
But what is the number? Luckily, there is a very nice website allowing you to play with all the parameters in both the Drake and the Seager Equations, so you can see how they alter the final estimate. The settings shown above are for the "today's optimistic" option. Pressing calculate will give you 750 planets, while  the "Seager original values" only give you 0.45 planets. Running the Drake equation with the original settings results in 10 communicating civilizations in our galaxy. Note that the drake and Seager equations rely of completely different detection techniques, that in part explain the differences.

Does it matter for speculative biology? Well, you could say that speculative biology has to start with astronomy, so yes. In the last of these 'equation' posts, a forthcoming post on the 'Nastrazurro Equation', I will try to apply all this astronomical reasoning to speculative biology in another way. Soon. Probably.

Thursday, 1 November 2018

Furaha in ImagineFX

ImagineFX is a Bitish magazine devoted to art in science fiction, fantasy and gaming settings. Its webiste is here, and here is its YouTube channel. Most of the content is about digital painting, but they also discuss 3D applications, a bit of hardware and conventional art.

They devote several pages to work sent to them by readers, and so I decided several months ago to try my luck. I sent five images with a bit of text and waited. I wouldn't write this if the result would have been 'Thank you but no'. So, some as yet unseen images of Furaha will feature in issue 168 of Imagine FX, that will go on sale in the UK on Friday 2nd November (I think that this is the December issue, by the way). I was informed that that issue will reach the US, Canada and Australia three weeks after that date.

Click to enlarge
I haven't seen the issue yet, so I have no idea whether they will devote one or two pages to my work nor which paintings they selected. I just thought that those of you who absolutely cannot wait, and who live in the UK, might wish to know. The cover is shown above so you will know what to look for. I expect to get my own copy shortly, so I will probably write some more about it before the magazine becomes available beyond the UK.

Oh yes; a post on the 'Seager Equation' will appear this weekend, and one on the 'Nastrazzurro Equation' probably two weeks later.