< Is it me, or does the rest of Galaxy look *drastically* different than our solar system? All this talk about extrasolar planets and possibilities for life, yet virtually all of the other solar systems we've been able to detect look radically different from our own -- most of which look completely unsuitable for the presence of life. A rocky planet 8 times the size of Earth? Gas giants in inner orbits?>

Again I argue that you need to look at the technology you have. THe ability to detect planets is a few years old. Just because we don't have the technology to find anything smaller yet does not mean that it does not exist. Like using a microscoppe instead of a scanning electron microscope and sayting that because we can't see atoms they do not exist.

In a few decades with better instruments in space assuming we still are able to mount a space program we might find lights blinking back at us. But we don't have the resolving power to do that yet.

Physics has changed and has remainded a constant. We have made the transition from Newtonian to quantum and maybe we will move to strings or something else. However the physics we know is far from a constant. It is not the physics of the Universe that changes but our understanding of it.

"They may be small, but they're very hot. They're the archaea, an ancient branch of microbial life on Earth discovered by scientists in 1977. Unlike the better known bacteria and eukaryotes (plants and animals), many of the archaea can thrive in extreme environments like volcanic vents and acidic hot springs. They can live without sunlight or organic carbon as food, and instead survive on sulfur, hydrogen, and other materials that normal organisms can't metabolize.

An enzyme, alcohol dehydrogenase (ADH), is derived from a member of the archaea called Sulfolobus solfataricus. It works under some of nature's harshest volcanic conditions: It can survive to 88 deg. C (190 deg. F) - nearly boiling - and corrosive acid conditions (pH=3.5) approaching the sulfuric acid found in a car battery (pH=2). ADH catalyzes the conversion of alcohols and has considerable potential for biotechnology applications due to its stability under these extreme conditions."

"Thermotoga is an Archaea organism, which is bacteria-like, and is another example of a so-called extremophile. It has adapted to conditions in hot springs and hydrothermal vents, thriving at temperatures up to 90C. As well, there are mats of bacterial organisms that live in 160C temperatures around hydrothermal vents more than 1000m beneath the ocean surface"

"For example, the bacterium Deino­coccus radiodurans (‘radiation-resistant weird-ball’) has been identified in cans of meat that had been sterilized (or so it was thought) with gamma radiation. While a thousand ‘rads’ of ionizing radiation is enough to kill a person, this bacterium can survive 12 million rads."

"And another newly discovered species of worm, Hesiocaeca methani­cola, has been found living on the seafloor in the Gulf of Mexico—the only animal known to colonize methane hydrate ‘ice’. This crystalline mixture of water, methane and other hydro­carbons freezes into a solid only under high pressures and relatively low tem­pera­tures—surely one of the most specialized environments in the world."

"...the toughest animals on Earth by far are the ‘tardigrades’. You can freeze them, boil them, dry them, starve them and even put them in a vacuum—yet they still bounce back.

The form of these little creatures (mostly less than 1 mm (one twenty-fifth of an inch) long) has earned them the nicknames of ‘moss piglets’, ‘bear animalcules’ and ‘water bears’. With their stumpy legs, tiny claws and slow, lumbering gait they really do look like a microscopic bear.19 Around 700 species of tardigrades have been found in habitats ranging from the freezing peaks of the Himalayas to the hottest, driest deserts, right down to the deepest ocean trenches of the Pacific."


If you assume that all life is carbon-based, you still are left with a habitable temperature range of 0 to 160C based on what we know about earth life. Radiation seems to be a factor that can be overcome. Same with high pressure. As well as temporary environmental deviations (120 years in the above example) outside of favorable conditions for survival.