Stephen Hawkin: waarschijnlijk geen leven buiten de Aarde:

[Pieke]

terug on topic:

In recent years, life forms have been found on Earth that thrive in places where the sun doesn't shine and oxygen is not present because no photosynthesis takes place. Microbes have been discovered that survive on the energy from the chemical interaction between different kinds of minerals, and others that live off the energy from the radioactive decay in rocks. The ecosystems are completely independent of oxygen or organic material produced by photosynthesis at Earth's surface.

[kiko]

Oorspronkelijk geplaatst door Pieke

terug on topic:
In recent years, life forms have been found on Earth that thrive in places where the sun doesn't shine and oxygen is not present because no photosynthesis takes place. Microbes have been discovered that survive on the energy from the chemical interaction between different kinds of minerals, and others that live off the energy from the radioactive decay in rocks. The ecosystems are completely independent of oxygen or organic material produced by photosynthesis at Earth's surface.

Dat sluit naadloos aan bij mijn standpunt dat er teveel verondersteld wordt dat buitenaards leven op de één of andere manier zou aansluiten met Aards leven wat betreft opbouw en zuurstof e.d.

[KrisKras]

Hier enkele voorbeelden van extremofielen, zoals boven aangehaald:

Acidophile: An organism with an optimum pH level at or below pH 3.
Alkaliphile: An organism with optimal growth at pH levels of 9 or above.
Endolith: An organism that lives in microscopic spaces within rocks, such as pores between aggregate grains. These may also be called cryptoendoliths. This term also includes organisms populating fissures, aquifers, and faults filled with groundwater in the deep subsurface.
Halophile: An organism requiring at least 2M of salt, NaCl, for growth.
Hyperthermophile: An organism that can thrive at temperatures between 80-121 °C, such as those found in hydrothermal systems.
Hypolith: An organism that lives inside rocks in cold deserts.
Lithoautotroph: An organism (usually bacteria) whose sole source of carbon is carbon dioxide and exergonic inorganic oxidation (chemolithotrophs) such as Nitrosomonas europaea. These organisms are capable of deriving energy from reduced mineral compounds like pyrites, and are active in geochemical cycling and the weathering of parent bedrock to form soil.
Metalotolerant: capable of tolerating high levels of dissolved heavy metals in solution, such as copper, cadmium, arsenic, and zinc. Examples include Ferroplasma sp. and Ralstonia metallidurans.
Oligotroph: An organism capable of growth in nutritionally limited environments.
Osmophile: An organism capable of growth in environments with a high sugar concentration.
Piezophile: An organism that lives optimally at high hydrostatic pressure. Common in the deep terrestrial subsurface, as well as in oceanic trenches.
Polyextremophile: An organism that qualifies as an extremophile under more than one category.
Psychrophile/Cryophile: An organism that grows better at temperatures of 15 °C or lower. Common in cold soils, permafrost, polar ice, cold ocean water, and in/under alpine snowpack.
Radioresistant: resistant to high levels of ionizing radiation, most commonly ultraviolet radiation but also includes organisms capable of resisting nuclear radiation.
Thermophile: An organism that can thrive at temperatures between 60-80 °C.
Xerophile: An organism that can grow in extremely dry, desiccating conditions. This type is exemplified by the soil microbes of the Atacama Desert.

http://en.wikipedia.org/wiki/Extremophile