Dragon's Egg (41 page)

Figure 5
. Relative Shapes of Cheela Bodies Under Influence of Gravity and Magnetic Fields: A, no magnetic field but strong gravity; B, near the magnetic poles magnetic stretching compensates for gravity; C, near the magnetic equator the cheela elongate along the magnetic field
.

Figure 6
. Squad Leader North-Wind with Short Sword and Dragon Tooth (Copyright 2050 by Swift-Killer, White Rock Clan)

A cheela’s eyes are a remarkable example of parallel evolution. In structure and function they are close parallels to the bright blue, stalk-supported eyes of the scallop shellfish on earth. The eyes of the cheela are about 0.1 mm =100 microns in diameter. To give the eyes adequate resolution, they must use wavelengths of 0.1 microns = 1000 angstroms or smaller. Thus, the normal range of cheela vision is the UV region, 1000 angstroms to 200 angstroms, although they can see down into the X-ray band if there is enough illumination. Some individuals (Bright’s Afflicted) can see up into the violet end of the human visual range (4000 angstroms).

The illumination for seeing comes primarily from the glowing surface of the star. At a temperature of 8200 K the neutron star crust has adequate flux in the long-wavelength part of the cheela vision band (700-1000 angstroms), but it cuts off at 600 angstroms. Things that are hotter (cheela bodies at 8500-9000 K, and hot illumination sources from 10,000-50,000 K) not only have more photons, but their “color” shifts toward “blue” and the resolution goes up. Cooler things, (like the top of a cheela or a plant) have a shift to longer, “redder” wavelengths. (See
Figure 7
.)

Figure 7
. Photon Flux on Dragon’s Egg

The story of Dragon’s Egg and its inhabitants is covered in great detail by Nobel Laureate P. C. Niven in Reference 4. To date, this is the only book to win the Nobel, Pulitzer, Hugo, Nebula, and Moebius prizes in the same year (2053).
Figure 8
is taken from the second volume of this definitive three-volume study/story and illustrates the major cultural migrations of the developing cheela.

Figure 8
. Historical Migrations of the Developing Cheela

According to ancient myths of the cheela, they are descended from a “chosen clan” that was driven from the northern hemisphere by a hateful Dragon God, who was said to live inside what is now the Mount Exodus volcano. The Dragon God sent blasts of fire, rivers of molten lava, and dense smoke to drive the cheela southward into a purgatory region where they were forced to travel in the hard direction (across the magnetic field lines), through a “feeling lost” region covered with dense smoke.

The cheela use a combination of magnetic and Coriolis fields for directional homing. In the “feeling lost” region, the lines of magnetic direction are parallel to the lines of rotation, and the cheela lose their inherent sense of direction and feel lost.

The smoke just above the equator is due to an interaction
between the east-west magnetic field and the rotation of the star. The smoke from the volcano travels predominantly along the magnetic field lines until it reaches the east and west poles, where the magnetic field lines dip into the surface. The smoke then leaks out at the magnetic poles and moves again along the magnetic field lines, but now along the equator, driven by the equatorial “trade winds” in the atmosphere. The star thus has a crescent shaped band of smoke in the magnetic longitude of the volcano, and a circular band just above the spin equator.

The “chosen clan,” driven from their original home by the Dragon God, finally moved southward across the spin equator to the southern hemisphere of the star, leaving the purgatory region behind. They found a land of plenty, with many edible plants and animals, but no other cheela. Their experience would be similar to the first entry of humans into the North American continent. Like the deep water barriers on earth, the “feeling lost” regions at the spin equator had produced a psychological barrier to the cheela that had kept the southern hemisphere isolated until then.

In this new land, the “chosen clan” discovered a bright star sitting just over the south pole. The very bright star was our sun, only 2120 AU (1/30 of a light year) away. A monotheistic religion developed based on worship of the God-star Bright. The “chosen clan” grew, and split into many clans, but all clans stayed under the loose rule of a Leader of All Clans.

The development of the cheela from a nomadic tribe into a great empire that finally established its rule over the entire star is well covered in Niven’s book.

The relative time scales between the cheela and the human race is still a subject of debate among experts,
since the cheela physiology is so drastically different from human physiology.

The basic unit of time on Dragon’s Egg is the revolution rate of the star, which is 5.0183495 rps, or a period of approximately 0.1993 seconds. Some experts have equated one turn of the star with one human day, giving a relative rate of 0.43 million to one. Others point out that since there is no night or day on the neutron star and the cheela, who never sleep, are active the full turn, that the ratio should be closer to a million to one.

The cheela use a base 12 number system (they have twelve eyes) and their next unit of time after the turn is a great of turns or 144 turns. They occasionally use a dozen turns, but it has never had the same significance as the week does to humans. A great of turns is 28.7 seconds, while a human year is 31.6 million seconds. The ratio of a human year to a cheela great of turns is 1.1 million to one.

From studying the history of the cheela we have learned that a cheela spends about 12 greats (six minutes) as a hatchling, 12 greats as a young apprentice, 30 greats (15 minutes) as a worker, 12 greats as an Old One tending eggs and hatchlings, then the rest of its life (maximum of 24 greats or 12 minutes) as an Aged One. All of these indications lead to the conclusion that the effective relative time scale between the cheela and humans is approximately one million to one.

Human transmission rate: The laser communication link from Dragon Slayer (see Dragon Slayer) up to St. George (see St. George) had a transmission rate of 400 MHz. This gave a bit rate of 200 megabits/sec., assuming good error correction practices.

Cheela reception rate: Since the cheela effectively live a million times faster, the human messages from the 400 MHz laser communication link were received at a maximum of 200 bits/cheela sec., which is about 5 words/cheela sec. This is a slow facsimile rate (a little slower than you can read).

Total bits transmitted: In 0.5 human day (43,200 seconds) the humans transmitted 10 trillion bits from the 25 HoloMem crystals in their ship’s library down to the cheela.

HoloMem Storage: Each HoloMem holds about 0.4 trillion bits. Since the HoloMem crystals are cubes 5 cm on a side, their volume is 125 cc. This means that each bit has the equivalent of a cube 7 microns on a side for storage. In that 7 micron cube there are about a trillion atoms.

Total HoloMem storage: A printed page holds roughly 350 words, 2100 characters or 15,000 bits. A book of 330 pages is about 5 million bits. The HoloMems could hold about 2 million books. For comparison, in 2050, the United States Library of Congress held about 50 million items (books, newspapers, trade publications, copyright items, etc.)

The spaceship that took the humans to Dragon’s Egg was a primitive monopole-catalyst fusion rocket. Its basic structure was a cylinder 500 meters long and 20 meters in diameter, with large spherical external tanks of liquid deuterium fuel. The mass ratio was about 10. St. George accelerated at 0.035 gees, and reached a speed of 0.035 the speed of light at its turnover point. The total trip time out to the neutron star was 1.94 years.

The scientific spacecraft used for the close approach to the neutron star was a seven-meter sphere with a spinning tower 1.6 m in diameter and 2.5 m tall, containing the microwave sounder, infrared telescope, laser radar, star image telescope mirror, and other star-oriented instruments. When in synchronous orbit about the star, the science instrument tower on the top of the ship was aligned in the direction of the north spin pole of the neutron star. The bottom end of the science
sphere had a viewing port that looked southward toward the distant Solar System.

Around the equator of the ship were six viewing ports that looked out at the neutron star whirling about the ship. The ship was inertially stabilized, so that the distant stars stayed fixed in the viewing ports. The ship, being in orbit around the neutron star with a period of 0.1993 seconds (5.018 rps), rotated with respect to the neutron star at 5 times a second. The science turret was de-spun at the orbital rate so that the instruments pointed to the star at all times. (The entire space ship could not be rotated at those speeds; had it been, the crew would have been thrown against the outer wall with a force of 350 gees).

Figure 9
through
12
are diagrams of the three decks and a side view of the scientific spacecraft, Dragon Slayer. The steady component of the residual gravitational tidal fields around and inside the ship are shown by arrows. In addition to the steady component, there is an alternating acceleration component of about the same magnitude as the steady component, which varies twenty times a second as the four-lobed gravity pattern of the neutron star and tidal compensator masses rotates about the ship five times a second.