Dragon's Egg (40 page)

Dragon’s Egg is a nearby neutron star. It has a mass of about one-half that of the Sun but a diameter of only 20 kilometers. It is spinning at 5.0183495 revolutions per second, has a gravitational field at its surface of 67-billion gees, and a magnetic field of close to a trillion gauss. As is shown in
Figure 1
, the star has four poles. In addition to the normal north and south spin poles, it has “east” and “west” magnetic poles that lie almost on the equator. The lines drawn from the east magnetic pole in
Figure 1
are the lines of magnetic longitude. The actual magnetic field is three-dimensional, and extends for some distance out into the region around the star.

Figure 1
. Dragon’s Egg

Figure 2
. Interior Structure of Dragon’s Egg

The internal structure of Dragon’s Egg is shown in
Figure 2
. The center has a liquid core 7 km in radius containing superfluid neutrons, a small quantity of superfluid protons, and enough normal fluid electrons to balance the charge on the protons. At the very center of the star, where the densities and pressures are highest, there are various exotic elementary particles mixed in with the neutrons.

Over this core of liquid neutrons is a 2 km thick mantle of crystalline neutrons and nuclei. The crystalline
crust varies from pure neutrons near the liquid core to nearly all nuclei near the top of the mantle. The outer crust of the star consists of neutron-rich nuclei (mostly iron) with a density near the surface of about 7 million grams per cubic centimeter. The number of neutrons in the outer-crust nuclei increases with depth, while the spacing between the nuclei decreases. The boundary between the outer crust and the mantle is the “neutron drip” region, where the neutrons can “drip” out of the highly neutron-rich nuclei and wander over to close-by neighboring nuclei.

The crust and mantle are solid structures over a liquid core. As the star cools and shrinks, the crust cracks and thrusts up mountain ranges. The mountains vary in height from a few millimeters to as much as 10 centimeters. The higher mountain ranges poke up out of the predominantly iron-vapor atmosphere, which becomes negligible at about 5 cm.

The large Mount Exodus volcano in the northern hemisphere of Dragon’s Egg is a volcano that formed over a deep crack in the crust of the star. The liquid material at the lower depths rises through the fissure to form the volcanic shield. Because of the temperature differential with depth and the beta decay that occurs in the nuclei as they rise to regions of lower density, the lava can release enough energy to maintain its flow against gravity. Volcanos such as Mount Exodus can build up lava shields many centimeters in height and hundreds of meters in diameter and will finally cause starquakes.

Starquakes involve the drop of a lava shield or mountain range by a few millimeters in the 67-billion-gee gravity field of the star. Starquakes in several pulsars have been detected from the Earth by observing the slight decrease in the period of the pulsar due to the decrease in inertia of the star from the lowering of the mountain range.

Dragon’s Egg was the product of a supernova explosion that occurred about 500,000 years ago at a distance of 50 light-years from the Solar System. In the process of formation, the neutron star/pulsar acquired a significant proper velocity of 30 km/sec (one light-year in 10,000 years or 6 AU in one year). The star was first discovered by space scientist V. Sawlinski in 2020 (see Reference 1). He detected its radio pulsations using the CCCP-ESA (See Acronyms—Ancient National Organizations) Out-of-the-Ecliptic probe, which was 200 AU up out of the planetary ecliptic plane. (See
Figure 3
showing the relative position of Dragon’s Egg, Sol, and the OE probe in 2020.)

At the time of its discovery in 2020, Dragon’s Egg was at a distance of 2300 AU from earth. When the humans finally arrived at the star in the first interstellar spacecraft, St. George (see St. George), the distance had narrowed to 2120 AU. At the time of this edition (2064) the star is at a distance of about 2040 AU. It will reach its point of closest approach of 250 AU in about 300 years, then recede again. Some perturbation of the outer planets is expected, but there should be no significant effects on the orbit of Earth.

The position of Dragon’s Egg in the sky was determined by S-Y Wang (see Reference 2) to be almost at the same declination (+70 degrees) and right ascension (11.5 hours) as Giansar, the bright star at the end of the constellation Draco (The Dragon). Its position among the constellations in the northern sky is shown in the simplified star chart of
Figure 4
.

By the time the humans discovered Dragon’s Egg, life forms had evolved on the neutron star. (Amazingly enough, the possibility of the existence of life on a neutron star was predicted almost a century ago by the radio astronomer F. D. Drake in Reference 3. Dr. Drake was a great-grandfather of Amalita Shakhashiri Drake, one of the crew on Dragon Slayer.) The first forms of life on Dragon’s Egg were plants, which lived by running a heat cycle between the hot crust and the cold of the sky. These plants later evolved into mobile animal forms.

Figure 3
. Near-Soler Space in 2020 AD (to scale)

Figure 4
. Northern Constellations in 2020

The dominant animal life forms on the star are called cheela. Since they are intelligent, the cheela have roughly the same complexity as humans. That implies that they have the same number of nuclei, so it
is not surprising that they weigh about the same as humans—70 kg. The cheela are flat, amoeba-type creatures about 2.5 mm in radius (0.5 cm in diameter), and 0.5 mm high, with a density of 7 million g/cc.

The atomic nuclei that make up the cheela do not have captive electron clouds to keep them isolated from each other, but instead share a “sea” of free electrons. Because of the resulting close proximity of the nuclei, it is as easy for cheela nuclei to exchange neutrons as it is for human atoms to exchange electrons. The nuclei couple into “nuclear bonded molecules” by neutron exchange. Since the cheela use nuclear coupling instead of molecular coupling in their bodies, their rate of living is about one million times that of humans.

Cheela can form crystalline “bones” when needed, but normally keep a more flexible structure and can flow around and into instruments to operate them. Because of the high gravitational field, cheela do not have strength to extend themselves more than a few mm above the crust. Their psychology with respect to gravity, height, and things-over-your-head is identical to the ancient science fiction stories by Hal Clement about the alien beings called Mesklinites.

The magnetic field on Dragon’s Egg dominates everything. The velocity of sound, the opacity of the atmosphere, the force it takes to move, the flow of lava and landslides, the pressure of the atmosphere, and many other things, vary by ratios of 10:1 from a direction along the magnetic field to a direction transverse to the field. The structure of the crustal surface consists of close-packed, dense “hairs” aligned along the magnetic field. These are horizontal along the magnetic equator and vertical at the magnetic poles.

It is easier for things to move along the magnetic field lines than transverse to them. But this also means that energy can be extracted by loss mechanisms for motion along the field lines, whereas transverse to the
field lines, there is little motion due to the rigidity, so there are few losses. Since the electromagnetic fields in light are transverse to the direction of propagation, it is easier to see
along
the magnetic field lines.

Even the nuclei in the bodies of the cheela have their aspect ratio changed as much as 10:1 in the direction of the magnetic field, since it is easier for the protons in the nuclei to move in the direction of the magnetic field than across it. Thus, as is shown in
Figure 5
, a cheela at the magnetic pole will be 10 times taller than one at the equator, and one at the equator will be 10 times wider toward the magnetic poles than transverse. Because of this variability, the concept of “length” was slow to develop in the cheela sciences. Even the cheela measuring sticks vary, and if the cheela make surveys, they will find that according to the number of measuring sticks needed to count off a distance on the star, their home is “flattened” 10:1 near the magnetic poles.

The actual cheela body is, of course, much more complex than the stereotyped diagrams of
Figure 5
. A more lifelike picture is shown in the sketch in
Figure 6
. This was drawn from memory by the Leonardo da Vinci of Dragon’s Egg (and first cheela Keeper-of-the-Sender), Troop Commander/Astrologer Swift-Killer. The Trooper in the drawing is Squad Leader North-Wind (identified by his two-button insignia of rank). He is holding a short sword and a dragon tooth (although squad leaders did not usually carry the long spear). The two puckered sections in his side are either carrying pouches or eating orifices. The small seminal fluid ejection holes under each eye-stub are the primary sex organs unique to a male cheela.

The cheela communicate by strumming the crust with their lower surfaces (tread) to produce directed vibrations in the neutron star crust. The strong magnetic fields polarize the surface material and since the crust has a nuclei lattice and an electron sea, the cheela have three modes of talking: long-talk—along the magnetic field using Rayleigh-type compressional waves; short-talk—transverse (shear) waves for communication across the magnetic field lines; and fast-talk—using electromagnetic fields generated by their bodies to excite the electron sea. Since fast-talk travels at the speed of light, it is somewhat faster than the two acoustic waves, but it is more highly attenuated and is used mostly for whispering.