Saturday, November 5, 2011

A Memo to J.J. Abrams

Picking science fiction movies apart for their scientific gaffesboth major and minorhas a long and venerable tradition. When I first saw J.J. Abrams' Star Trek "reboot" in the theater (twice) I enjoyed it immensely. However, the weaknesses of the whole idea of a "supernova" taking out a single habitable planet, the home-world of the movie's villain, was not lost on me at the time (I will not address the "red matter" MacGuffin in detail here). While watching it again the other day on DVD, I thought of a minor tweak that would make the plot element of the destruction of a planet more scientifically plausible and still retain the following storyline benefits:
  1. the plot would still involve a black hole (cue ominous music)

  2. the word “supernova” (hereafter: “SN”) would still be used on-screen

  3. the word “hypernova” (i.e. a really bad-ass big brother to a mere supernova) could be used as well

  4. an opportunity would be created for some really awesome, not yet depicted on the big screen, FX "disaster porn"

So, beginning at the beginning...

Throughout their lives, all the stars we can see on a clear night (and even those we cannot) exist in a state of equilibrium between the outward force of the energy released by the fusion of lighter elements into heavier ones in the star's core, and gravity, which acts to collapse the matter of the star to a central point. When a star is being born from a molecular cloud, as it condenses, the pressure and temperature at its core increases steadily until at about 15 million K,i thermonuclear fusion begins. Once the fusion process has begun, the the outward radiation pressure of the energy thus released begins pushing back against gravity, settling into a state of what is called hydrostatic equilibrium and there matters stay, at least as long as there is enough of the "fuel" needed to keep fusion going and pushing back against gravity. In the case of our own Sun, it is just barely middle-aged for a star of its size and luminosity and will go on largely as it is today for another 5 billion years.

All good things must come to an end and so it is too with the fusion gravy train. The problem is that a star's supply of elements that can be fused is not infinite. As lighter elements are fused into heavier elements, those heavier products make their way to the star's core, but that is where the highest temperatures and pressures, necessary for fusion, are also. The kind of fireworks called for by the movie going public in their lust for great science fiction disaster porn needs a star (or stars) many tens of tens of times the mass of our sun.

The scale of the disaster porn I'm referring to can only come from the most energetic cosmic phenomena observed by humans, the only thing more powerful yet conceived by science is the Big Bang. These cosmic phenomena are called gamma-ray bursts (GRB's). Gamma-rays are the most energetic, highest frequency form of electromagnetic radiation. To provide a tangible sense of the energy of gamma-rays, anyone who has ever had x-rays taken has likely worn one of those heavy, lead-lined "bibs" to shield the more delicate parts of our bodies (e.g. the reproductive organs). Gamma-rays can penetrate up to several centimeters of lead, over ten times the thickness of lead used to shield patients getting x-rays.

Some (though not all) observations of GRBs are associated with supernovae (the plural form of the singular “supernova”). All by themselves, supernovae are powerful enough (in the visible light part of the spectrum) that for decades, astronomers have used a particular species of supernovae, designated by astronomers as a "Type Ia" supernovae, as part of the "cosmic distance ladder." The circumstances under which they form make them a "standard candle"ii that can briefly outshine the galaxy of which they are a part. Conventional supernovae release these incredible amounts energy in a blast that is a more-or-less spherical wave front of high-speed particles, visible light, and hard radiation, fading over a period of days or even weeks. What makes GRBs different is that they release at least as much energy as supernovae, but do so in seconds, and in two focused directional "beams" thought to be aligned along the magnetic poles of a freshly-minted black hole.

(Any real astrophysicists reading this, please be kind in the hate mail I'm sure you will want to send after what I say next.) As a strictly visual metaphor (the physics behind it, other than the magnetic field connection, is quite distinct) think about the auroras visible from Earth's extreme north and south latitudes, the point being that "stuff" can interact with magnetic fields. Another similar cosmic phenomenon are "pulsars," thought to be (on very solid observational grounds, mind you) rapidly rotating neutron stars (i.e. failed black holes) whose magnetic poles are offset from their rotational poles, creating a "lighthouse" effect, both in the radio and the visible light spectrum, and are detectable for many light-years. In fact, their signals are so precisely timed, when first detected by radio telescopes in the 1960's they were referred to as, somewhat tongue-in-cheek, LGM's for "little green men" as there as there was no known natural phenomena that were that regular.iii

There are several, and not necessarily mutually-exclusive, posited "progenitors" for GRBs,1 but there is much that is still unknown–leaving a lot of room for science-fictional speculations. Without going into too much detail (a temptation I frequently face) there are short and long-lived (remember, time is relative) GRBs. The so-called "long" GRBs (those lasting more than 2 seconds), have always been observed in connection with supernovae, specifically, a kind of supernovae called collapsars. Collapsars are supernovae whose progenitors are stars of 40+ solar masses, massive enough to have developed a solid iron core, iv that collapses straight (well, almost) into a rapidly-rotating black hole without pausing at the neutron-star phase. Short GRB's–those lasting less than 2 seconds, and commonly only fractions of a second-making them hard to detect as one has to be looking at it as it happens to catch it–are thought to result from the merger of a black hole with a neutron star, or of two neutron stars.

If I were writing a script, I would use the black hole + neutron star plot device (you could still have the "red matter") as some sort of "ultimate weapon" gone cosmically awry. You could even use the old science-fiction trope of the "Frankenstein complex"–either the hubris of the scientists involved thinking they can accurately predict and control where the beams will end up pointing, or the militaristic leaders who ignore the warnings of their scientists. The creators could also be some unknown threat from elsewhere (can you say "sequel"?). In the altered time-line of the reboot, presumably, the Borg (unarguably the baddest adversaries the Federation has ever faced) are still out there and the events of the Star Trek: Enterprise episode "Regeneration" still happened. I'm seeing possibilities J.J.! Just think about the disaster porn FX you could get out of the massive jets from the GRB pulverizing star systems as it bores a path of interstellar destruction through the galaxy!

I am too young (at 47, I seldom get to say that much anymore) to remember the original Star Trek (ST:TOS) during its first-run on NBC. Somewhat against type, I was drawn to science fiction by my interest in, and love of, science–and especially astronomy–while it seems that many scientists of my generation were first turned on to science by a love of science fiction. A local TV station started showing reruns of ST:TOS in my first year in junior high, and perhaps not coincidentally, the same year Star Wars: A New Hope was in theaters. Add to this the presence in my school library of the James Blish short-story adaptations of all 79 episodes of ST:TOS and the Alan Dean Foster novella-length adaptations of the animated series (ST:TAS) and you have a perfect trifecta. I was such a voracious reader (I still am) that I had read all of Blish's adaptations long before I saw all the ST:TOS episodes.

As an adult science-geek, one of the things I enjoyed about Star Trek: The Next Generation (ST:TNG) was that the writers included bits of "sciencey" stuff that one could read about in recent issues of Scientific American, like "cosmic strings" or "dark matter," cutting-edge science stuff. What astronomy undergrad would turn down a chance to review the sciencey bits of a script (if done right, keeping the whole of the script a secret would not be that hard).

Heck, I'm available-and rather cheap, too!

1 G. Vedrenne, Gamma-Ray Bursts: The Brightest Explosions in the Universe, Chapter 8, (Springer; In Association with Praxis, Berlin; New York; Chichester, UK, 2009).

iIn the Kelvin, or absolute temperature scale, water freezes at 273.15 , boils at 373.15, and all molecular/atomic motion ceases (that is one definition of "temperature") at 0 (zero) Kelvin (note the absence of the "⁰" degree sign). For a star the size and composition of our Sun, the core temperature (partly a function of its mass) is 15 million K.

iiIf a light source lies an unknown distance away, but you know that the source is a 100 watt light bulb, and you have a light meter, the kind used in old cameras, all you have to do measure the power of the light that reaches your meter, do a little math, and viola, you know how far away the light bulb is.

iiiSome pulsar signals are so stable (remember the accuracy claim of the first quartz watches?) make them suitable for use as cosmic “radio beacons” for interstellar navigation. The plaques carried by the Pioneer 10 and 11 probes as “greeting cards” to any advanced extraterrestrials that might come across it millions of years in the future illustrated the position of Earth with respect to 14 pulsars using a binary-type code.

ivThe creation of elements, via fusion, higher than iron on the periodic table require an input of energy rather than having energy left over to power the star and push back against gravity-which makes iron, as Isaac Asimov titled an essay on supernovae, the "dead-end middle."

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