Aliens only in movies; died billions of years ago: Scientists

Aliens only in movies; died billions of years ago: Scientists

Saturday, January 23, 2016 2:50 pm


Extra terrestrial alien in a movie

Extra terrestrial alien in a movie

Life on oth­er plan­ets would likely be brief and go ex­tinct quick­ly, say sci­en­tists at Aus­tral­ian Na­t­ional Un­ivers­ity in a new stu­dy.

In re­search aim­ing to un­der­stand how life might de­vel­op, they con­clud­ed that new life would com­monly die out due to run­away heat­ing or cool­ing on their fledg­ling plan­ets.

“The uni­verse is probably filled with hab­it­a­ble plan­ets, so many sci­en­tists think it should be teem­ing with aliens,” said Ad­it­ya Cho­pra, lead au­thor of a pa­per on the re­search, pub­lished in the jour­nal As­tro­bi­ol­o­gy.

“Early life is frag­ile, so we be­lieve it rarely evolves quickly enough to sur­vive.”

“Most early plan­e­tary en­vi­ron­ments are un­sta­ble. To pro­duce a hab­it­a­ble plan­et, life forms need to reg­u­late green­house gas­es such as wa­ter and car­bon di­ox­ide to keep sur­face tem­per­a­tures sta­ble.”

About four bil­lion years ago Earth, Ve­nus and Mars may have all been hab­it­a­ble, he not­ed. But a bil­lion years or so af­ter forma­t­ion, Ve­nus turned in­to a hot­house and Mars froze in­to an ice­box. Early mi­cro­bi­al life on those two worlds, if any, failed to sta­bi­lize the rap­idly chang­ing en­vi­ron­ment, said co-au­thor Char­ley Line­weav­er. “Life on Earth probably played a lead­ing role in sta­bi­liz­ing the plan­et’s cli­mate,” he added.

Chopra said the the­o­ry solves a puz­zle.

“The mys­tery of why we haven’t yet found signs of aliens may have less to do with the like­li­hood of the or­i­gin of life or in­tel­li­gence and have more to do with the rar­ity of the rap­id emer­gence of bi­o­log­i­cal regula­t­ion of feed­back cy­cles on plan­e­tary sur­faces,” he said.

Wet, rocky plan­ets, with the in­gre­di­ents and en­er­gy sources re­quired for life seem to be com­mon through­out the cos­mos. But as phys­i­cist En­ri­co Fer­mi point­ed out in 1950, no signs of sur­viv­ing extra-terrestrial life have been found.

A plau­si­ble so­lu­tion to Fer­mi’s par­a­dox, say the re­search­ers, is near uni­ver­sal early ex­tinction, which they have named the Ga­ian Bot­tle­neck.

“One in­tri­guing pre­dic­tion of the Ga­ian Bot­tle­neck mod­el is that the vast ma­jor­ity of fos­sils in the uni­verse will be from ex­tinct mi­cro­bi­al life, not from mul­ti­-cellular spe­cies such as di­no­saurs or hu­manoids that take bil­lions of years to evolve,” said Line­weaver.

Culled from World-science.net: Why Aliens are silent

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