Diamonds in the Sky (18 page)

Ellen smiled. “For eternity, if you want.”

Her crest rose high, her eyes went open and bright. “Then, yes, take us with you.”

Afterword:

This story was first published in an anthology,
The Age of Reason
, edited by Kurt Roth, at SFF.net in 1999. In addition to making supernova astrophysics an experimental science it touches on some of the “big issues,” like “what does it all mean?” and “where are we going?”

I was asked to briefly elaborate on some of the science in the story. Hopefully the following will prove useful, or at least point people in the right direction.

A hundred thousand years before Sani’s cancer took hold, the great blue disk and ultraviolet arms of the majestic Whirlpool galaxy filled David Martin’s field of view.

The Whirlpool galaxy is about 23 million light years away, south of the tip of the Big Dipper’s handle. It is about half the mass of the Milky Way and 70% of its diameter. Assuming David is traveling near the speed of light, he is only a little more distant from the galaxy than the visible spiral is wide. Google “Whirlpool Galaxy.”

Orienting the superconducting loops in every nanocell of his body
…

David and Ellen’s personalities reside in a swarm of trillions of “nanocells.” These are conceived to be roughly the size of biological cells, but made of much sturdier stuff, and not permanently specialized. Linked as a data processing system, they form a supercomputer. As a physical system, the cells can join each other in almost any imaginable configuration. Read Kurzweil’s
The Singularity is Near
, and project.

…
he tacked against the faint plasma breeze of the galaxy’s central black hole, gradually bending his path toward his chosen decelerator.

Curious, David and Ellen reconfigured themselves into a great conducting loop and soared in the plasma currents of the cluster…

When a charged particle (the “plasma breeze”) encounters a magnetic field, it is deflected one way, and, action equaling reaction, the object generating the field is pushed in the other. A current loop creates a magnetic field with a north and south pole, much like a bar magnet’s.

Most of a billion years of experience was set carefully aside from conscious thought so that they could enjoy real-universe sensation again.

Emulated emotions, such as boredom, can be turned off, when inconvenient. In this case, the fun of experiencing something anew can be lived over and over.

As they left the region, they reformed themselves into a thousand telescopes, which they spread into a globular constellation a hundred million kilometers across; a giant’s eye…

David and Ellen can see Sani’s world by forming a large optical synthetic aperture telescope. The wider the telescope, the smaller the objects it can see. For the mathematically inclined, R ≈ 1.22 L/A where R is the resolution in radians. L is the wavelength of light and A is the telescope aperture. To get actual size, rather than the angular size, multiply by the distance to the object. In visible light (a wavelength of 500 nm, or 5 E-7 m), a one-meter-wide telescope would be able to resolve objects 5 E-7 radians apart. A 100 million kilometer-wide telescope (1E11 m) might resolve 5 km sources at 100,000 light years. That’s ideally — the source must provide enough photons for all the elements of the array to combine, which limits this trick to bright objects.

There! An old ruddy, overinflated windbag of a star circled a white dwarf grown heavy from the giant’s effluvia. If it grew heavy enough, it would explode as a supernov…

The white dwarf would become a “Type Ia” supernova. Wikipedia has a good article.

More massive stars form ultra dense iron cores by fusion reactions of lighter elements. The cores collapse when they become more massive than Chandrasekhar’s limit (Google “Chandrasekhar”), about 1.4 solar masses, starting a process that leads to the explosion we see and a neutron star remnant.

A Type Ia may not go that way. A Type Ia supernova starts out as a white dwarf a little less than Chandrasekhar’s limit which then gains mass — generally hydrogen and helium from a nearby companion star that is losing mass in its red giant stage. This forms a layer on top of the carbon and oxygen “ash” from previous fusion reactions. As the white dwarf gets close to Chandrasekhar’s limit, the picture gets unclear. But the fusion reactions that create heavier elements may happen all at once in a thermonuclear explosion that “deflagrates” the star before it can collapse into a neutron star. Since this always happens at about the same mass, and produces supernovae of about the same brightness (about 5 billion times solar luminosity at peak), Type 1a supernovae can be used as “standard candles” to gauge the size of the universe. Google “standard candles.”

…before they had moved out of the Mind of Mars to seek adventure in the real cosmos with nanocell bodies.

In this future history, the
Mind of Mars
is a supercomputer on the moon Phobos in which billions of human-descended Martians live as computer programs in virtual worlds of their own choosing. They can go back and forth from biological, or other technological bodies, at will. It’s mentioned in
After the Vikings
(ScorpiusDigital.com).

Close enough to the orange star for heavy tides, it had a large moon locked in synchronous orbit of about a day and a half. The star’s gravity tried to stretch the system, adding orbital energy which the tides in the planet’s ocean tried to take away, pounding on its continents — neither, David thought, would win their argument in the lifetime of the orange-tinted star.

Imagine our moon in a geosynchronous orbit like communications satellites! We wouldn’t have the twice daily lunar tides, but we would still have solar tides, which are about half as strong. Modani’s world is closer to its dimmer, but not that much less massive, sun. Its solar tides are about as strong as our combined lunar and solar tides.

Reaching the star, they parachuted through its ionic wind, slowed to a planetary pace, and drank in the light of the star, giving trillions of trillions of tiny flywheels their fill.

A nanoscale flywheel composed of a single molecule is very strong per unit weight and can store much more energy than any conceivable chemical battery.

We may have to destroy their culture to save their lives.

When nuclear scientist Enrico Fermi realized that both alien civilizations and interstellar travel were at least physically possible, if not easy, with sufficiently advanced technology, he asked “Where are they?” One possible answer is that they are or have been here, but are very careful to avoid disturbing our culture — the way a human scientist might not interfere with a colony of chimpanzees. In “Star Trek” lore, this is called “the Prime Directive.”

Daiffidi told them how to build shelters that would protect them if the star exploded. They would need to live underground as a separate sun scorched the land for a few weeks.

To prevent the supernova, David and Ellen must trigger an “ordinary” nova, burning away the hydrogen and helium accumulating on the surface of the white dwarf. The result will be in the top range of ordinary nova luminosity, around a million Suns.

“…In the worst case, if the star explodes the large way, what will it be like?
…
the first radiation to escape the star will be neutrinos… The temperature of your planet’s mantle will increase a degree or so, almost instantly. Magma will start moving.

Maybe.

The nuclear reactions in the current model of a Type Ia supernova would still produce a lot of neutrinos, though maybe not as much as a core collapse. I’ve gone a bit beyond what I can show quantitatively here, though we have to allow some new astronomical discoveries to the hundred million years or so between our time and the story’s!

“…seconds later, a blast of photons will scorch your planet’s surface…”

There should be a gamma ray burst as the shock wave reaches the white dwarf’s surface. The “star” rapidly expands and, over the next few weeks, a huge ball of vaporized and highly radioactive nickel and iron will provide most of the energy. Big explosions take time.

But no one will be here. In the far reaches of your planetary system, we are preparing a fleet to take you to a new world before that happens. You’ll have a badly shocked culture, but better that then none at all.”

Moving an entire planet’s population to somewhere in space is not an exercise for those afraid of big numbers. But, when one does the math instead of arguing from personal incredulity, it isn’t impossible at all. At this point, I’d like to recommend a couple of Arthur C. Clarke stories on this theme:
Rescue Party
and
The Star
.

I’ll end with a graph of the luminosity of a supernova versus an ordinary nova versus days since the explosion. The left scale is in absolute magnitude — Google “absolute magnitude” for the Wikipedia article. The right scale is a log scale of luminosity with the sun equal to one.