Archive for December, 2012

Your Turn, Round 2-2: Life In Vacuum

For the second alien species in the Fermi Problems setting, I decided to go with another take on the “Where are they?” line.  Fermi’s argument for a spacefaring civilization spreading across the galaxy in only a few million years depends on a long period of nearly exponential growth and on a travel speed that is a significant fraction of the speed of light.  My friend Jacob Haqq-Misra has worked out some limitations on the rapid growth of civilizations, but I decided to design aliens who could not travel at more than 0.001 c.  This requires two things: a species that cannot handle high acceleration, and a technology base that does not allow them to either engineer themselves or robotic emissaries to accelerate faster or to build a rocket that can continuously accelerate for a very long time.

The latter is a rather severe limitation.  Accelerating at 0.03 m/s^2, a spacecraft would still reach 0.003 c after 1 year and cover ~8 lightyears in a century if the acceleration was sustained.  The later is unlikely for something internally powered: fusion rockets are limited to maybe 0.1 c peak speed, given the requirement to stop at the destination.  Even a Bussard ramjet is limited to 0.119 c by the exhaust velocity of the fusion rocket.  But I have set a speed limit of 0.001 c or 300 km/s.  Even a fission-reactor-powered ion engine could in theory reach or somewhat exceed that speed.  So, I needed to design a species that cannot handle high acceleration and can travel interstellar distances with nothing fancier than a chemical rocket.  Taking some liberties with biochemistry, I propose a biosphere that evolved on small asteroids in the nominal habitable zone of a binary made of two M-dwarf stars.  I picked CM Draconis because there is a lot of data available on it, it doesn’t have any large planets in the habitable zone, and it isn’t too close to Earth.  Once again, I gave the fictional version of it a name in addition to the catalog listing: Druk.  It happens that CM Draconis forms a hierarchical triple system with a white dwarf, GJ 630.1B, several hundred AU away.  Continuing the theme, call it Wyvern.

Low-Pressure Biology

I fully confess that the following is far more improbable than the ursians are, because the reservoirs for biochemistry to develop in are far smaller if for no other reason.  With that caveat, I ask for any reasons why it is impossible, rather than merely incredibly improbable (levels of likelihood comparable to large-scale quantum tunneling may be counted as impossible).  The improbable makes for good science fiction; the impossible is not allowed.

Things started somewhere like this (main-belt asteroid 253 Mathilde, imaged by the NEAR spacecraft).

Things started somewhere like this (main-belt asteroid 253 Mathilde, imaged by the NEAR Shoemaker spacecraft).

Consider a water- and carbon-rich asteroid, between a few hundred meters and a few tens of kilometers across.  The particular object we are discussing doesn’t exist anymore, but it was like billions of others: a rubble-pile of variously-sized grains.  Fine-grained material accumulates in dust ponds on such objects, and on a carbonaceous-chondrite object those grains will be rich in a slew of various relatively complex carbon compounds.  This much is well-established.

The fictional assumption that I invoked was for there to be enough chemistry going on in those dust ponds (using monolayers of water molecules on the grain surfaces?) to produce small closed membranes durable enough to keep their contents separated from the surrounding grains and protected from being shaken off a grain into the surrounding vacuum while still being permeable enough to allow new molecules in.  From there, chemistry proceeds to something that is self-catalyzing and rather like a protocell – similar to the bubble model of abiogenesis.

Given this admittedly out-there assumption, I can invoke evolutionary processes to expand this strange biosphere.  Cells with vacuum-tight walls, high radiation tolerance, and specialized molecule-sized valves survive better; on the surfaces of the ponds as well as beneath them and inside ejected meteoroids.  Photosynthesis takes over from feeding on primordial and cosmic-ray-seeded high-energy compounds.  Heterotrophs feed on the plants and on each other; larger and better-armored multicellular plants enjoy a survival advantage and larger animals evolve to feed on them.  Eventually, three-dimensional forests grow out from small cores – collecting a hundred times as much light as compared to if they only coated the rock.  I was inspired to this design by some speculation by Freeman Dyson and possibly by some of the pictures in Le Petit Prince.  Conveniently, these forests will be incredibly hard to observe over interstellar distances: they are dark in the visible, and infrared telescopes don’t have the same resolution as optical or radio arrays.  Even if they are seen, the forests will be confused for boring dead carbonaceous asteroids until and unless their orbits are known well enough to measure their masses from mutual perturbations – showing how low their densities are.

The first rock was destroyed in a collision within a few hundred million years of the first appearance of life, scattering microbes across the system in the debris.  Objects within the entire habitable zone have things growing on them; going too far out from the star causes un-insulated cells to freeze.  On a timescale of a hundred million years, each individual forest is destroyed.  On a much much shorter timescale, the plants break off rocket-propelled seed pods and solar-sail leaves that search for other objects using chemical-imaging tracers (the sail leaf idea was used by Larry Niven in the form of the ‘sail seed’).  The animals that don’t have sufficient hibernation and delta-v abilities of their own hitch rides.

And, because I said there would be one, an intelligent species of animal evolved in one of the larger forests and then spread.  I called them the neari – the etymology is a bit strained, but I hope it sounds cool enough.

Anatomy and Psychology

There is gravity, even on the smallest asteroids, although it can be effectively canceled for fast-spinning objects.  The neari can handle continuous loads of ~0.03 m/s^2 without having too many problems, and can do brief jerks up to several gees.  But they don’t have a physiologically preferred up and down or left-and-right, since the gravitational pull is a very gradual change as they navigate through the forests.  So I designed a body plan for them inspired by sea urchins, crabs, and T4-bacteriophage: an icosahedral central body with limbs (equally validly called ‘arms’ or ‘legs’) at the vertices.  The facets have specialized functions, but the neari are equally capable from all directions:

Concept art of a neari.  This one has mysteriously acquired a Rubik's Cube and a can of Pringles.  The top limbs to the upper left of the picture are holding on to a support (not pictured).

Concept art of a neari. This one has mysteriously acquired a Rubik’s Cube and a can of Pringles (that both of those were on my desk as I made this drawing is pure coincidence). It is looking directly at you with one of its optical eyes and obliquely with an infrared- and a nose-eye. The top limbs to the upper left of the picture are holding on to a support (not pictured).

Four facets contain mouths, with airlock throats leading into a central stomach (the mouths are also used to excrete waste).  Four are optical eyes, based around fish-eye lenses.  Four have lines of infrared-sensitive pits.  Four are blank on the surface, and underneath them are the neari’s central brain lobes.  And four have organs that work only in near-vacuum: nose-eyes.  This is an idea from Hal Clement: in vacuum, molecules travel long distances without collisions.  So a pinhole camera can make an image in molecules as easily as in light, as long as whatever it is looking at is putting out any detectable number of particles.  Neari exoskeletons and plant leaves smell only faintly.  A comet outgassing is detectable tens of thousands of kilometers away – far further along its tail.  An simpler version of this organ is used by the rocket pods and sail leaves to home in on objects.

The neari grow by molting and shedding their exoskeleton, a process which also allows the regeneration of limbs.  Molting grows less efficient with time, and eventually accumulated damage leads to death – although prompt injuries will kill a neari far more quickly.  The other way neari die is by giving birth.  To solve the problem of exchanging genetic material and maintaining a pressurized environment for the embryonic neari to grow in, two neari (of any two of the three different sexes) join along the blank faces and slowly fuse together.  The embryonic neari grow inside the merged exoskeleton, fed by their parents’ bodies.

These biological differences led to some important psychological differences between neari and humans (or ursians).  Neari never know their parents – they are raised by their aunts/uncles and cousins.  The individual is generally seen as less important compared to the family than it is for us.  And sex is not a recreational activity.  I have not fully explored how such different psychology will be reflected in neari culture.  There is one other relevant psychological trait, from the hazard of being stuck in space just out of reach of a claw-hold: neari get very anxious if they aren’t holding onto something.

Culture, Technology, and Starships

The neari culture at Druk is in many senses less fragmented than that of the ursians, even though they’re spread out over cubic astronomical units.  As of 70,000 BCE, you might have been tempted to call them a bronze-age culture.  But there is no such thing as technological levels – real technological developments are spurred by the environment, the available resources and knowledge, and random moments of inspiration.  The neari may have not have any metal other than nickel-iron, but they formed it into knives and hooks and parabolic focusing mirrors.  Reflecting telescopes and heliographs gave light-speed communication across all of Druk, at least at telegraph-equivalent bandwidth.  Writing preserved information.  The neari had chemical rocketry, using rocket pods, and solar sails, made by cultivating and then trimming the leaves of sail plants.  Travel between the forests, while slow and mass-limited, was inexpensive, and the neari understood Newtonian mechanics, radiation pressure, and numerical integration.

That said, the forests were isolated enough from each other that they retained very different cultures.  Wars were not unknown, although they were limited in scope by the very low population density.  Enough cooperation between forests did happen to organize large scale projects, including starships.

Druk has two red dwarf stars very close to each other, with an orbital velocity of ~75 km/s.  With a little extra help from the super-jovian gas giant (>5 AU from the stars) and Wyvern (~500 AU), a careful gravitational slingshot maneuver past both stars can give an escaping interstellar spacecraft a velocity of ~300 km/s.  And the neari already have things that can be turned into starships: comets (I got this idea from Greg Benford and David Brin).  Several cubic kilometers of comet ice/organics contain ~3e16 J of usable chemical energy, enough to support 100 neari and their life-support system for tens of thousands of years.  Select a comet about to make a close flyby of the stars, trim its orbit with high-speed impactors so that it gets ejected at high speed, jump on board before the flyby, afterwards adjust your trajectory using the gas giant or the white dwarf, and then burrow down under the surface for the long ride.

The problem with these comet boats is that they can only be targeted onto a certain range of trajectories, only a small fraction of comets are suitable (e.g. the comet has to be big enough to survive the stellar flybys), and the accuracy of the navigation can only be so good.  The comets jet out gas unpredictably at perihelion, and even if the comet boat’s trajectory was known perfectly that of the destination star isn’t.  The neari can measure parallax and proper motion accurately, but radial velocity is only approximate.  A 0.1 km/s error at launch would be 1000 AU at arrival, and the comet boat can’t change its velocity by too much more than that en route.

For purposes of the setting:

The neari did start to spread across interstellar space ~70000 years ago – launching comet boats every few thousand years.  But only one of them got close enough to its target star for the neari then on board to ditch the comet and stop.  The others are either confirmed to be dead, still flying through the void, or unknown in status because they stopped replying to heliograph calls centuries ago.  So Druk and Wyvern (the latter has a small debris disc out to a few hundredths of an AU from the star that the neari have settled) are still the main place to find the neari and there they are hard to see from parsecs away.

Does all of this work for a species that can travel over interstellar distances without being readily detectable, while simultaneously not spreading so fast that we should expect them to be here already?


Your Turn, Round 2-1: Fermi Problems

In 1950, while sitting at lunch, Enrico Fermi is said to have asked “Where are they?“.  Fermi liked to do order-of-magnitude physics, and had worked out that if intelligent life is common in the universe and can spread through space at a significant fraction of the speed of light, extraterrestrial intelligence should already be here.  So, where are the aliens?

There are many proposed resolutions to this paradox.   One is that there are very few places for life to evolve – the Rare Earth hypothesis.  That becomes significantly less likely the more we know about extrasolar planets.  At the same time, SETI has advanced to the point that we can say that there are no other Earth-like civilizations within a few tens of light-years of here and no Dyson Swarms within several thousand lightyears.  So even if planets are common, perhaps life is not.

And even if life is common in the universe, perhaps intelligence is not often selected for.  This may be contradicted by life on Earth, but it depends on the definition of intelligence.  Apes are intelligent.  Dolphins and whales are intelligent.  Elephants are intelligent.  Dogs and cats and raccoons are intelligent.  Taking non-mammalian examples, consider parrots and ravens.  Octopi and cuttlefish are pretty smart too.  But if by intelligent we use the pragmatic SETI definition of being able to build a radio or other technology readily detectable over interstellar distances, intelligent life has only appeared once on Earth.

Given all of that, there are still obstacles to a civilization or culture spreading across interstellar space.  There has already been a lot of speculation on this theme, both in the scientific literature and in science fiction, but I decided to design a hard sci-fi setting playing around with it anyway.  I’ve used the results in a couple of variously-bad short stories and one never-completed NaNoWriMo novel (it reached 50,000 words, but would need an incredible amount of editing and a lot more material to flesh out the plot).  A couple of years ago, I put the then-current version of the setting online here, but I’ve decided on some changes since then.  Name-dropping, I call the setting “Fermi Problems”.

I’ll talk about the cultures in the setting more briefly here, one at a time.  As last time, I ask you to take them to pieces – both the ways to get around the Fermi Paradox and the details of each group.  I apologize in advance for a general lack of appropriate graphics, and beg for fan art.

People Who Can’t Get To Space

At the risk of making each culture in the setting a Planet Of Hats, I assigned a single primary reason why each of them had not spread across interstellar space in a detectable way before now (both actual ‘now’ and the several-hundred-year future ‘now’ of the setting).

For the first culture I designed, I decided that they had not spread into space because they couldn’t get off their planet.  That meant a steep gravity well, which meant a gas giant planet.  Fortunately, the idea of life on a gas giant isn’t entirely absurd.  Carl Sagan and Ed Salpeter studied the possibility in some detail in 1978.  Organic chemistry in the clouds, driven by lightning and UV and particle bombardment, becomes self-catalyzing.  Microbial life can survive as long as it reproduces fast enough to outpace the droplets it is reproducing in falling down to points in the atmosphere where they get baked dead.  Lift is better, so bags of heated gas and floating clots of aerogel come to dominate the biomass.

The floaters look kind of like Cloud City from Star Wars, except biological and filled with gas bags and aerogel bricks.  The cloud decks would also be shorter vertically under Ursa's gravity.

The floaters look kind of like Cloud City from Star Wars, except biological and filled with gas bags and aerogel bricks. The cloud decks would also be shorter vertically under Ursa’s gravity.

Sagan and Salpeter were considering the possibility of life in the atmosphere of Jupiter, which probably does not exist.  So I put my fictional biosphere in the atmosphere of 47 Ursae Majoris b, one of the first extrasolar jovian planets to be found that wasn’t a hot Jupiter.  For the purposes of the setting, 47 UMa b is ‘Ursa’ and 47 UMa the star is ‘Big Bear’.

Once there is a large population of floaters, life could evolve into niches that don’t have lifting power of their own.  Some are parasitic plants.  Others are animals, using heavier-than-air flight to get from one floater to another – powered by muscle power and biological chemical rockets (based on oxygen or methanol burned with hydrogen, as if a bombardier beetle secreted methane and burned it with oxygen) .  One species of those animals eventually evolved intelligence and a technological society.  Call them the ursians.

The ursians have had a technological society for hundreds of thousands of years.  Artificial islands of aerogel blocks; blimps and jets to travel; genetic engineering of crops and of themselves; biochemical computers.  But they have no silicon, no iron, no aluminum, no titanium, no uranium.  The only source of those materials on the planet is grains of meteorite dust sieved out of the atmosphere.  The ursians cannot build rockets capable of getting off of Ursa. 

Orbital speed for the planet is ~75 km/s.  No chemical fuel provides sufficient impulse.  A gas-core fission rocket might be able to do the job, but requires uranium.  A fusion rocket could do it, but that would mean setting off an H-bomb without a fissile trigger since steady-state fusion devices do not have sufficiently high power density to provide enough thrust.   I had a large comet impacting the planet throw a floater into orbit, but the ursians on it did not survive.  They are quite efficiently confined at the bottom of a very deep hole, and not able to build high-power radio transmitters either.

Does this work as a way to have extraterrestrial intelligence that has been around for a very long time and maintains high technology without being obvious across interstellar distances?  Have I missed some way to throw objects into the sky or to generate monochromatic radio waves?

Superheroes Round 4: Spiderman

2012/12/19 2 comments

Spiderman.  There have been four movies in the last decade.  Wow.  I’m mostly going to cover the 2012 reboot, since I just saw that one on a plane, but I’ll give a mention to the others in passing.  As ever, here there be spoilers.

The movie is, in fact, about this guy.  He gets bitten by this spider...

The movie is, in fact, about this guy. He gets bitten by this spider…

Doesn’t Know His Own Strength

This was beautifully done, and I think, not well addressed in other cases where a character suddenly gets a ridiculous strength boost.

The morning after getting bitten by a spider, poor Peter Parker discovers that he lives in a world of cardboard.  He gets up, and tries to squeeze some toothpaste onto his toothbrush.  He overshoots, splatting a whole bunch onto the mirror.  Puzzled, he scrapes a bit off with his toothbrush, then turns the knob of the faucet… breaking it off.  Panicking, he jabs it back on over the water spewing out of the pipe, wraps it in a towel.  When he first tries to open one door, he breaks off the handle.  He manages to open the second door… very, very carefully.

And, consistent with learning to control his strength, he still has occasional oops-too-much moments later in the film.  But, just how strong is Spiderman?


Okay, folks, it’s physics time!

There are several scenes in the film where Spiderman propels himself upward by first throwing a bit of webbing, stretching it, then springing upwards.  Let’s see just how ridiculous this gets.

Per one scene near then end on the OsCorp tower, let’s say the webbing stretches up about 20 m, and that each strand had a diameter of about 0.001 m.  Spiderman stretches the two strands by about his height.  Let’s call that 2 m, just to make the math easy.  That’s then enough energy to vault Spiderman for about the height of the webbing.  Assuming Spiderman weights about 75 kg, that means it takes 15 kJ of energy to send him up that high.  That means he has to store that much energy in the spring (of the webbing), which put the spring constant k at about 7500 N/m.  That’s how much force you have to exert to stretch the webbing per meter.  So, at maximum extension, that implies Spiderman is exerting a force of about 15000 N.  To put this into perspective, that’s enough force to lift a small car.  … and probably also enough force to cause some serious damage to the building, not to mention Spiderman himself.

Doing a little more math with that spring constant and the dimension of the webbing, I can estimate the pressure applied — which comes out to about 5×10^9 Pa, or 5 GPa.  This is approximately the ultimate tensile strength of even carbon fiber… at least according to Wikipedia.  That is, the point at which it starts to narrow in width… which occurs not too long before breaking.  (It’s also beyond the yield point of most materials, which is where they will no longer return to their original shape after stretching.  And the Hooke’s Law discussion above no longer works.)  Thus, the webbing would have to be something like carbon nanotubes…

… then again, these material concerns also apply to Spiderman’s flesh and bone.

Suffice it to say, this trick is a bit of a stretch.

Mass Conservation

Shapeshifters goof this one up all the time.  And it bothers me.

In this case, it’s Dr. Curt Connors first regrowing his arm… then growing into a superhuman lizardman.  I mean, come on.  Where is the mass for all of the extra muscle and bone coming from?  Was he guzzling a bunch of protein shakes and some bone meal beforehand, or what?  And he’s not the only one with this problem — The Hulk, Mystique, The Thing… where does all that mass come from?  Or go, when they shrink back down?  At least for Connors we get to see the material all peel away when he de-powers.

There’s one book I’ve read before, where werewolves existed.  However, transformation was not only messy, but any bits that “fell off” got eaten in order to converse mass.  So, they weighed the same before and after.  And they were also hungry a lot of the time.  I’d say what book it was, except I can’t remember the title or the author, and it wasn’t all that great.

Unconscious = Dead

Whenever somebody dies heroically on film due to being shot or the like, people start mourning as soon as the person passes out.  The person’s probably just in shock (at least to start with) due to blood loss and so forth.  They’re not dead yet.  Call an ambulance, do CPR, try to slow the bleeding… stuff like that.  Don’t just start crying like there’s nothing you can do.  And it happens twice in this film!

Seriously, Spiderman, take a first aid course.

SciFi Round Nine: Asteroid Impact

The near-Earth asteroid 4179 Toutatis is flying by Earth right now.  Closest approach was 0.046 astronomical units (just under 7 million kilometers) on 2012 Dec 11.

This is not unusual.  Toutatis’ orbital period is just over 4 years, so it flies by the Earth every 4 years for 24-28 years when the objects are in phase with each other.  Toutatis was briefly observed in the 1930s, during the last series of approaches, but formally discovered by Christian Pollas in 1989, just after the 1988 flyby.  It has been observed with radar imaging during every flyby since – 1992, 1996, 2000, 2004, 2008, and I’m part of the team observing it right now.  There is also a series of optical images from the Chinese Chang’e 2 spacecraft, which flew by Toutatis on Dec 12.  So we know quite a bit about the asteroid’s shape, spin, and internal structure.  There’s a lot of interesting science there.

We also know Toutatis’ trajectory in space, down to a few hundred meters over the last twenty years.  Running the orbit forward, we can say that it will not hit the Earth anytime in the next several hundred years and almost certainly not within the next several thousand (it can’t get closer than ~700,000 km away until the orbit has drifted from the current ellipse).

But despite all of this, there is still considerable nonsense associated with people claiming that Toutatis will hit.  This willful ignorance of reality annoys me, so I will defuse my annoyance by discussing asteroid and comet impacts in fiction.

The Truth

Asteroids do hit Earth.  Objects the size of a car fireball in the upper atmosphere every few months.  In one case, 2008 TC3, the object doing the fireballing was discovered approximately 30 hours before impact, and a careful search of the predicted impact zone duly found appropriate meteorites.  Objects several tens of meters wide hit the Earth every century or so.  The most recent one flattened a big expanse of forest in Siberia a bit over a hundred years ago.  Objects several kilometers wide hit on a tens-of-millions-of-years timescale.  The most famous of those is the Chixulub impactor, which triggered the mass extinction of most of the currently-living dinosaurs (the birds were the exception).

So there is an asteroid impact hazard.  It is very well-characterized, because we know the rate of past impacts in the geological record.  As the potential effects of a large asteroid hitting the Earth became well known in the late 1980s and early 1990s, the US Congress was persuaded to order and fund – through NASA – efforts to locate at least 90% of all near-Earth objects larger than 1 km in diameter (there are about 1000 of them).  That project was known as Spaceguard, and included a number of groups focused on discovering objects, better measuring the orbits of known objects, and understanding the physical properties of asteroids in general.  There were relatively few people working on this full-time in the beginning – the comparison was to the staff of a McDonald’s franchise.  But Spaceguard did its jobWe can now say that no near-Earth asteroid larger than 1 km in diameter will hit the Earth in the next hundred years.

The "Burger Bar That Saved The World", courtesy Nature (  Steve Ostro, who was my thesis advisor, is depicted in the lower right.

The “Burger Bar That Saved The World”, courtesy Nature. Steve Ostro, who was my thesis advisor, is depicted in the lower right.

More extensive survey programs now aim to push their completion limits for the near-Earth asteroids down to ~140 m or so.  That point is pragmatically defined: for smaller objects, the cost of finding them decades to centuries before they are going to hit is higher than the cost of finding any impactor a few days or weeks before impact and simply evacuating the blast radius.  The unknown near-Earth objects are not civilization-ending.  We will not all die from asteroid impact.

Should a few-hundred-meter object be found to be on a collision trajectory with decades of warning, there are well-developed plans for deflection.  Nukes are not necessary.  Kinetic impactors are useful for objects where slower and better-controlled approaches would take too long.  If you have enough time, you can just coat the object with a very thin metallic layer (paint or film) and let radiation pressure do the work for you.  But the favored method right now is something called a gravity tractor: put a spacecraft next to the asteroid and hover.  If you angle the rocket exhaust to miss the asteroid, then momentum goes from the exhaust to the spacecraft to the asteroid and the trajectory is very slowly and precisely adjusted.

So we will not be hit by a large asteroid anytime soon, and we can deal with the smaller ones.  There remains a slight impact hazard from long-period comets, which can’t be found more than a couple of years before any potential impact because they are too far away.  But that’s a once-per-hundred-million-years event, and there are ways to largely mitigate even an impact like that.

Works That Get Some Things Right

Although it is tangential to the plot, special mention goes to Arthur C. Clarke’s Rendezvous With Rama. In the backstory to the book, an object smashes into the Mediterranean in 2077 and ruins large sections of eastern Italy.  There is no such object in reality, but since Clarke was writing in 1973, that’s pardonable.  One part of the response to this impact is to set up a survey program called “Spaceguard” to find any other potentially hazardous objects.  Several decades later, the survey program discovers the alien spacecraft that the humans label Rama when it is still many months from closest approach to the Sun.  Clarke’s Spaceguard is of course the namesake for the real one.  His prediction was just 85 years or so behind the times.

As far as impacts themselves go:

In Larry Niven’s fiction, the impact effects are generally fairly well done.  In Lucifier’s Hammer, the impactor is a comet rather than an asteroid and a close approach turns into an impact when the comet outgasses unexpectedly.  The one problem with that is that that’s a known effect, so any comet coming close enough for outgassing to possibly cause an impact would be dealt with.  In Footfall, aliens dropped the snowball as part of an effort to terraform Earth to their liking.  In both cases, people and civilization do survive, although the details are unpleasant.  The Ringworld has suffered impacts too, punching holes through even its incredibly durable construction.  Niven was sneaky enough to specify the failure properties of the ring material so that it would bend enough that impacts breaking through from the outside would deflect the ring surface enough locally that the air would not all leak out.  Sufficiently large impacts onto the inside of the ring would still be a problem.

Unfortunately, these are the exceptions.

Those That Get Many Things Wrong

For the earliest impact stories, egregious failures to understand the effects of asteroid impacts can be partially pardoned by the knowledge at the time.  But some things can’t use that excuse.  In Jules Verne’s 1877 Hector Servadac, the eponymous hero and several dozen others are picked up by a passing comet.  Verne clearly didn’t understand what happens to material that goes from zero to roughly 20 km/s nearly instantly.  Of course, Verne was the man who proposed launching people to the Moon using a giant cannon with 20,000 g acceleration, so math was not his strong point.  By the 1930’s, the public had started to understand the principle of reaction engines.  So Balmer & Wylie wrote When Worlds Collide, in which spacecraft at least have rockets.  But they got the physics of impacts entirely wrong, as well as requiring various impossibilities in terms of the rogue planet that is doing the impacting.

When Worlds Collide, 1933.  Earth-Shattering Kabooms do not look like this.

When Worlds Collide, 1933. Earth-Shattering Kabooms do not look like this.

When Worlds Collide also illustrates one of the two ways that impacts get misinterpreted.  Since it was written, there has been a pattern of making impacts far worse than they would plausibly be, either by making the impacting object far too large or making it far too destructive for its size.  For example, Balmer and Wylie wanted to destroy the Earth and have the humans evacuate to one of the rogue planets that came in.  To do that, they invoke an impactor the size of Neptune.  That’s nonsensical overkill – we should refer to Earth hitting it rather than it hitting the Earth.  In reality, for a rogue body hitting the Earth, it would only need to have a diameter of ~4000 km (smaller than Mars) to disintegrate the planet entirely.  I quote The Impact Effects Calculator.  There are also few enough rogue planets that the expected rate of such objects hitting the Earth is far longer than the age of the universe.

Books may often be bad, but movies are the most egregious offenders when it comes to doing impacts wrong.  Most particularly are the two impact films of the late 1990s: Armageddon and Deep Impact (no relation to the spacecraft of the same name).  Both are horrifically bad in terms of the science.

Armageddon is the worse of the two, since it has an asteroid as large as Ceres be pushed by a comet onto an impact trajectory that is moving about 50 times too fast for anything gravitationally bound to the Sun.  That is equivalent to shooting a rhinoceros with a handgun and having the rhino go into Earth orbit It doesn’t workArmageddon gets still worse in that a space shuttle is somehow scrambled to launch within two weeks and match that impossible speed, that somebody built a bomb with a yield per mass ten thousand times higher than total conversion, and that Bruce Willis could bury that bomb four hundred kilometers underground.  I could go on, but it is So Bad It’s Painful.

Deep Impact has a more reasonably sized comet doing the impacting, and it is discovered with over a year of warning.  Good enough.  But it still overestimates the effects of the impact.  An 10-km comet hitting the ground would cause a mass extinction.  But it wouldn’t kill everything.  You wouldn’t want to be within 1500-km or so of ground zero, or anywhere on an adjacent coast if it hit in the ocean.  But everyone outside of that zone would be relatively okay.  A year is time enough to evacuate the zone and stockpile food for the impact winter, if everyone in the world is preparing for it.

That is the problem with Deep Impact: an amateur astronomer finds the comet.  That does happen in reality.  But then no-one else finds it, and there is an attempted coverup and Masquerade.  That’s even more nonsensical than the other examples we gave in our Masquerade post.  The comet is quite literally shining in the sky.  Anyone can see it.  And there is no reason to attempt a coverup and every reason to make it public, so that people can prepare.  So the science is better but the sociology is equally absurd.

Thinking through all of this has made it clear to me that the public misunderstanding of the impact hazard is closely tied to popular misrepresentations of it.  My normal approach is to try and explain things correctly.  But how can I work around the public perception of Bruce Willis?

Superheroes Round 3: Blade

2012/12/06 Leave a comment

Eric Brooks is Blade, the vampire hunter who is half-vampire himself.  Having most of their strengths and none of their weaknesses, Blade hunts them day and night.  He blames them for the death of his mother and the thirst for blood.  The latter is suppressed by a serum made by his friend and tech support guy, Whistler.

They do avoid the sparkly atrocity that seems to be so popular lately, but then there are other problems.  Perhaps the biggest one is the Masquerade, but since we’ve covered that already, let’s see what else we can find…

This is Blade. Hunting vampires is serious business.

Somebody Made Blade On Purpose

Blade is referred to as the “Daywalker” by the vampires.  As it turns out, this is quite deliberate on the part of Frost, the villain of the piece.  Frost is aware of an ancient prophesy, which requires the sacrifice of twelve “pureblood” vampires (born vampires, not turned from humans) as well as the blood of the Daywalker, to be fulfilled.  Completing the specified ritual will supposedly turn him into La Magra, the vampire god.

So, Frost turns Blade’s pregnant mother.  She dies (and later comes back with sharper teeth), and the young Blade is only partially exposed, thereby becoming the Daywalker.  Frost uses Blade’s mother as a distraction to help slow him down while setting him up to be drained of blood.

Problem here is that Blade is still awesome.  And stubborn.  And hates vampires.

So, bottom line: Frost gets his godlike vampire powers.  And then Blade kills him.  Oops.  Why Frost didn’t just adopt Blade as a young boy, and raise him to be fanatically devoted to the cause, I don’t know.

Skin Care

One of the few things that Frost gets right is working on defending himself against the standard vampire weaknesses.  Can’t go out in the sunshine?  Sunscreen.  Well played.  And the whole vampire-deity thing is desirable in part because it stops the standard weaknesses.  Of course, they end up defeating him by means of a non-standard weakness.  Turns out, anti-coagulants are not good for vampires.

On the other hand, Frost (and the other vampires) should re-think their use of tattoos to mark themselves and their human minions (who are typically hoping to be turned themselves).  Sure, it’s kind of cool to have a mark that shows your allegiance.  However, it makes it all too easy for Blade to ID a person as a minion.  All you have to do is find the mark.

Even if they insist on the tattoos, they could use UV ink.  Oh, wait, UV is kind of unhealthy for vampires.  And googling “IR Ink” doesn’t get me anything obvious.  The vampires would be better off following the recommendation from an addendum to the Evil Overlord List:  “My undercover agents will not have tattoos identifying them as members of my organization.”

Speaking of vampiric fashion…

What Happens to a Vampire’s Clothes?

Whenever Blade kills off a vampire, the vampire conveniently and promptly turns into a bunch of slightly-glowing ash that quickly cools.  No bodies for the cops to pin on him, which is helpful.

The problem?  The vampires’ clothes get turned to ash, too.

This could imply several things.  The conclusion that the clothes are part of the vampire is off, since they’re seen in different outfits, and their clothing doesn’t heal with them.  The other two possibilities are that the heat from their death ashes their clothes, or that there’s some sort of magic aura when they die that takes their immediate possessions with them.

Either way, this is a problem.  In the former case, where it’s the energy of the dying vampire that toasts their clothes, this implies very high temperatures.  Anybody (like, say, Blade) in the vicinity will be burned by the bits that go flying.  And then, of course, there’s the potential for hot vampire ashes to set things on fire.

If it’s actually some kind of weird magic thing, well… that is kind of weird.  You would think that this could then cause all the vampire’s possessions to catch on fire, or to accidentally ash anything close to the dying undead.  Regardless, the brightly glowing and clearly hot ashes should still have the potential to set things on fire, damage the ground that they fall on, and that never seems to happen.

Viral Vampirism

The vampires in the setting are supposed to work by means of a viral infection.  Anyone who’s infected by the virus, which requires transmission via bodily fluids (saliva getting into the victim’s blood), will eventually succumb to vampirism.

This is a not uncommon approach to “explaining” vampires (or zombies, for that matter), but it does have some problems, even when overlooking the the difficulty of having a single virus cause so many serious changes all at once.  For instance, the consequences of the retrovirus infection supposedly include an inability to produce hemoglobin.  Since that’s the protein that red blood cells use to carry oxygen to tissues, and a given red blood cell only lasts about three to four months before getting recycled, the vampire is going to be running dangerously low on red blood cells only a few weeks after turning.  This is presented as the reason that vampires need to suck blood.

The problem here is that the blood cells in question will be broken down in the vampire’s stomach.  Including the hemoglobin that the vampires supposedly need.  To make this work, the vampires would have to actually need the break-down products from the blood (such as heme, which based on some skimming can be absorbed through the small intestine), or else have differently configured stomachs.  In the latter case, the stomach is probably much less acidic, and less capable of breaking down other foods.  While this might match up with the fact that we never see the vampires eating anything other than blood, it does leave the question of where they get the calories to do all their acrobatics, feats of super-human strength and speed healing.  The reactions to garlic and UV and so on are explained as “allergic” reactions, but it’s not clear why a vampire should go up like tinder when you stake them. It’s also unclear how you can get some kind of partial exposure in utero to make Blade, rather than a scary baby vampire.

How this semi-scientific explanation of vampirism lines up with the other aspects of the story is also a bit frustrating.  The vampire virus coexists with a magic ritual using one member apiece from specific vampire families and transforming Frost into some sort of strange blood-monster.  For bonus points, the ritual is described by an ancient prophesy.  None of these things is given any sort of scientific explanation akin to that of vampirism itself, or even an attempt at one, and the contrast is jarring.  Perhaps this is a matter of taste, but if you’re going for technomagic, I’d prefer a neater blending — in this case, make the virus clearly magical to account for everything it can do.

Magic virus or no, Frost does well in terms of taking advantage of modern technology… but still needs to know better than to create his own worst enemy.