Laputan Logic
Friday, December 13, 2002
  Bugs living in the dangdest places With the recent discovery of tiny creatures living off radiation in ancient pockets of water several kilometres beneath the Earth's surface, it's tempting to ask whether or not the crust of the Earth is really just one big deep, hot biosphere.
There are strong indications that microbial life is widespread at depth in the crust of the Earth, just as such life has been identified in numerous ocean vents. This life is not dependent on solar energy and photosynthesis for its primary energy supply, and it is essentially independent of the surface circumstances. Its energy supply comes from chemical sources, due to fluids that migrate upwards from deeper levels in the Earth. In mass and volume it may be comparable with all surface life.
It may be that we shall find a simple general rule to apply: that microbial life exists in all the locations where microbes can survive; that would mean all the locations that have a chemical energy supply and that are at a temperature below the maximum one to which microbes can adapt. There would be no locations on the Earth that have been protected from "infection" for the long periods of geologic time. Chemical energy must be available, but it must not be liberated spontaneously without the intervention of the organisms. That means we have to be concerned with regions in which the chemical processes that can release energy would not run spontaneously; the temperature must be below the activation temperature for the reactions, or a set of reactions must be involved that give out energy on completion, but that require intermediate steps which absorb energy. Research on the deep microbial life would allow one to judge the extent of it on the Earth, and with that one can expect to gain an insight into the extent to which microbial activity has contributed to the chemical evolution of the crust and its various mineral deposits. Prospecting techniques for minerals and for petroleum may be improved. The derivation of petroleum is a subject of great economic importance, and new information may profoundly influence the prospecting techniques and the estimates of the quantities of petroleum and natural gas that remain to be discovered. The other planetary bodies in our solar system do not have favorable circumstances for surface life. The numerous bodies that have solid surfaces all have conditions of atmospheric pressure and temperature unfavorable for the presence of liquid water. Mars, deemed the least unfavorable in this respect, has been investigated (by the Viking landers) and no indications of any biological activity has been found. With this, it seemed that there was little or no chance of finding any other life in the solar system. With the possibility of sub-surface life, the outlook is quite different. Many planetary bodies will have temperature and pressure regimes in their interiors that would allow liquid water to exist. Hydrocarbons clearly are plentiful not only on all the gaseous major planets, but also on the solid bodies: the large satellites, numerous asteroids, the planet Pluto, comets and meteorites; and there is every reason to believe that hydrocarbon compounds were incorporated in all of the planetary bodies at their formation. The circumstances in the interior of most of the solid planetary bodies will not be too different from those at a depth of a few kilometers in the Earth. The depth at which similar pressures and temperatures will be reached will be deeper, as the bodies are smaller than the Earth; but this fact itself does not constitute any handicap for microbial life. If in fact such life originated at depth in the Earth, there are at least ten other planetary bodies in our solar system that would have had a similar chance for originating microbial life. Could the space program ever discover this? Is there a possibility of finding life of an independent origin on some of the other planetary bodies? We shall have to see whether microorganisms exist at depths on the Moon, on Mars, in the asteroids, and in the satellites of the major planets. Such investigations may become central to that great question of the origin of life, and with that they may become a central subject in future space programs.
  An Ancient Link to Africa Lives on in Bay of Bengal
Inhabitants of the Andaman Islands, a remote archipelago east of India, are direct descendants of the first modern humans to have inhabited Asia, geneticists conclude in a new study. But the islanders lack a distinctive genetic feature found among Australian aborigines, another early group to leave Africa, suggesting they were part of a separate exodus. Their physical features — short stature, dark skin, peppercorn hair and large buttocks — are characteristic of African Pygmies. "They look like they belong in Africa, but here they are sitting in this island chain in the middle of the Indian Ocean," said Dr. Peter Underhill of Stanford University, a co-author of the new report. Genetic analysis of mitochondrial DNA, a genetic element passed down only through women, shows that the Onge and Jarawa people belong to a lineage, known as M, that is common throughout Asia, the geneticists say. This establishes them as Asians, not Africans, among whom a different mitochondrial lineage, called L, is dominant. The geneticists then looked at the Y chromosome, which is passed down only through men and often gives a more detailed picture of genetic history than the mitochondrial DNA. The Onge and Jarawa men turned out to carry a special change or mutation in the DNA of their Y chromosome that is thought to be indicative of the Paleolithic population of Asia, the hunters and gatherers who preceded the first human settlements. The mutation, known as Marker 174, occurs among ethnic groups at the periphery of Asia who avoided being swamped by the populations that spread after the agricultural revolution that occurred about 8,000 years ago. It is found in many Japanese, in the Tibetans of the Himalayas and among isolated people of Southeast Asia, like the Hmong. The discovery of Marker 174 among the Andamanese suggests that they too are part of this relict Paleolithic population, descended from the first modern humans to leave Africa. A finding of particular interest is that the Andamanese do not carry another Y chromosome signature, known as Marker RPS4Y, that is common among Australian aborigines. This suggests that there were at least two separate emigrations of modern humans from Africa, Dr. Underhill said. Both probably left northeast Africa by boat 40,000 or 50,000 years ago and pushed slowly along the coastlines of the Arabian Peninsula and India. No archaeological record of these epic journeys has been found, perhaps because the world's oceans were 120 meters lower during the last ice age and the evidence of early human passage is under water. One group of emigrants that acquired the Marker 174 mutation reached Southeast Asia, including the Andaman islands, and then moved inland and north to Japan, in Dr. Underhill's reconstruction. A second group, carrying the Marker RPS4Y, took a different fork in Southeast Asia, continuing south toward Australia.
The Anadaman Islands are under the administration of the Indian Government. Searching Google for images of the Andamanese reveals an interesting casebook of attitudes...
ONGE Onges are one of the most primitive tribes in India. They belong to the Negrito racial stock and they have been relegated to the reserved pockets both at Dugong Creek and South Bay of Little Andaman Island. They are also diminishing in number. They live in a remote corner of the country in a small pocket. They are the semi-nomadic tribes and fully dependent on the food provided by nature. They have now experienced the impact of outsiders. At the same time efforts at befriending them have proved to be successful. They have been provided with pucca hut type houses, food, clothes, medicines, etc by the Administration. They eat turtle, fish, roots and jack frutis and etc. They have developed artistry and craft. The Onges can make canoes. A primary school has been functioning at the Dugong Creek settlement of Onges. This tribe has become laid back and dependent in their ways. Also their rate of reproduction has become very low.
JARAWAS They are now friendly and voluntary seek medical assistance. They do not have good canoes but can make rafts which they build to cross the streams. The year 1974 was a land mark in the history of Jarawas. Dropping of gifts was done in February and March 1974. After establishing this friendly mission with the Jarawas, the contact party of the Administration quite often met the Jarawas and gave them gift items like banana, coconut and other fruits. With the passage of time, the behavioral pattern of Jarawas have changed. Till the beginning of 1998, they remained hostile, but now they are coming out of the jungle quite often and are becoming friendlier. For nearly a year there is no incidence of killing of villagers by the Jarawas. On the other hand, the Jarawas are coming out from their habitat to mix with the local people. After giving them gift items like bananas, coconuts, etc,. they are being sent out to live in their own natural habitat, with view not to force them to have a taste of the civilized world. Isolated so long, the Jarawas otherwise appear to be healthy, with smooth skin, deep curly hair, long and sturdy hands and legs and sturdy bones. They are physically fit for hunting, fishing. Unlike, other tribes mention earlier, the Jarawas are not welfare dependent people. As nomadic tribes subsisting on hunting, fishing and gathering activities, their traditional food articles consist of boar (wild boar), turtles and their eggs, crabs and other shore animals, etc. wild pig fruits and honey.
SENTENELESE The Sentinelese are the inhabitants of North Sentinel Island. The area is about 60 Sq. Kilometers. They are probably the world’s only Paleolithic people surviving today without contact with any other group or community. They are considered as an off-shoot to the Onge Jarawa tribes which have acquired a different identity due to their habitation in an isolated and have lost contact with the main tribes. The Sentinelese are very hostile and never leave their Island. Very little is known about these hostile tribes.
the best source for all things Andaman, as noted before on this blog, is Lonely Islands: The Andamanese.  
Monday, December 09, 2002
  Victorian Nitrogen Laser Did an amateur scientist and correspondent of Michael Faraday (1791-1867) really invent the laser in 1856?
Faraday, I tell you, this observation is of some singular importance, the crystal will brightly glow, concentrated at one point, even when removed from the apparatus by several feet, but only when exactly in line with the gap! I think that some form of electrical effluvia is produced from the expanded spark, which travels like an invisible sunbeam until its effects are known through the juxtaposition of fluorspar or an assistants eye. I urge you to try these experiments Faraday, should you find the time.
Thanks, Pete 
  Hand-drawn Holograms reposted from the Collaboratory One sunny day, when amateur scientist Bill Beaty was walking through a car park when he noticed a black car that appeared to have a series of interesting spots and highlights on its hood. On closer inspection, he also noticed several hand prints which had a curious property: they didn't appear to be on the surface of the paintwork at all but instead looked as though they were floating several inches below the surface. In some cases they even looked like they were floating above the surface. After thinking about this he came to realize that he looking at a kind of holographic effect but this kind of hologram didn't require all the usual paraphernalia nor was it caused by light wave interference. It was a kind of holography that could be used to draw pictures in 3D by hand. A 3D image requires two images, a different one for each eye. The hand-prints looked different to each eye because they were being made up from scratches in the paintwork and scratches can look very different depending on the viewing angle. The owner of the car had evidently cleaned his car with a gritty polishing mit which had left a series of long curved scratches on the hood of the car. In the process an image of his hand was preserved in 3D. To understand this, imagine that you're holding a sheet of black shiny plastic outside in the sun. Now with a compass, make an arc in the plastic. When the sun hits it you will get what is called a specular highlight (a bright spot or point of light) somewhere along the arc. If you close one eye the spot will appear at one place on the arc, if you switch to the other eye, the spot will appear at a slightly different place on the arc. This is because the angle of each eye is different relative to the reflective edge of the arc and the sun. As you vary the radius of this arc, the amount of displacement between these two spots will also vary. The smaller the radius of the arc the more the positions of the spots will differ from each other. Now when you view the arc with both eyes open, the two spots will merge to form a single spot and the amount of displacement between the two spots will combine to create a sense of depth, i.e. how far away the combined spot appears to be. So that's the basic idea but the interesting thing is that it is possible to use it to draw 3D images by hand. An image done this way is made up of many spots of light and is constructed by marking a sheet of black plastic with a great number of arcs. For example, to construct a simple "V" shape that floats a few inches below the surface of a black plastic sheet: First draw the "V" at the bottom of the sheet. Then take a compass and place one end at some point on the "V" and make an arc at the top of the sheet. Move to another point on the "V" and make another arc. Repeat this process over and over until you have covered as much of the "V" as possible and as a result you will have a series of arcs up at the top of the sheet. Now take it outside to view it under bright sunlight. The apparent depth of the "V" is set by the radius of the compass.
You can find out more details about this effect on Bill Beaty's page, as well as tricks for drawing more elaborate images such as 3D polyhedra. Beaty spends a bit of time justifying his assertion that this is really a type of hologram and he compares it to other reflective holgrams like the ones you often find on credit cards. He also mentions the possibility of building large outside installations that use chrome wire or tubing instead of scratches.  
Fanciful. Preposterous. Absurd.

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