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CONTENTS of entire timeline

CONTENTS of 59,999,999 BC- 51,000 BC Large land and aquatic mammals appear; many kinds of primates appear (almost as many go extinct); an island continent finally disappears for good; the Mediterranean valley turns into the Mediterranean Sea; human beings emerge, develop housing, clothes, lamps, and drugs, breed dogs, use horses; Mars dies (or goes dormant)

This page last updated on or about 10-31-05
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Approximately 5,000,000 BC: Any predominant non-human galactic empire in our own galaxy apparently begins no earlier than now

Any alien civilization in the Milky Way galaxy which may be destined to someday dominate the entire galaxy and meet up with a 21st century or later humanity is likely now to be at least equivalent in technology to what humanity will be between 10,000 BC and 2000 AD.

Such a civilization could be located on the opposite side of the galaxy from Sol system, and still have time to develop advanced spacecraft, and reach 21st century or later Earth-- assuming they advance technologically at roughly the same rate as humanity.

A civilization located closer than this to Sol could mature later to still encounter us at around the same time. One located as far as possible from us in the galactic disk, but developing considerably later, might not encounter humanity until 3000 AD or later.

At least fractional (10-20%) lightspeed propulsion for interstellar travel methods appear feasible to humanity, even at our present primitive level of technological know-how (2000 AD).

Thus, five million years would be a reasonable amount of time for a single star faring race to colonize the entire galaxy, even if equipped with only 10% lightspeed propulsion, and an average of 400 years was spent inbetween establishing a fresh colony and undertaking further colonization missions from that colony. If an interim period of 5000 years is substituted for the 400 number, then 50,000,000 years would be required to colonize the galaxy.

Possible resolutions of the Fermi Paradox due to things like aliens adhering to a Star Trek style "Prime Directive" demanding non-interference with primitives, or accidentally destroying themselves early in their history, or being disinterested in colonization altogether, might only work if the total number of emerging galactic civilizations is relatively small.

Just one star faring race with a history and motivations similar to our own, which avoided self-destruction, would be sufficient to colonize the entire galaxy no more than 50 million years after they began.

-- Scientific American: Feature Article: Where Are They?: July 2000 ["http://www.sciam.com/2000/0700issue/0700crawford.html"] by Ian Crawford

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