Saya ulang:
"Sikap yang rasional itu, yang diambil antara lain oleh ateis, adalah terus
berusaha melakukan penelitian untuk mengetahui bagaimana "awal kehidupan itu
terjadi". Atau, bagi yang bukan ilmuwan untuk menunggu hasil penelitian para
ilmuwan.
Sikap yang tidak rasional, yaitu sikap yang diambil antara lain oleh teis,
adalah belum apa-apa udah nyerah dihadapan pertanyaan tentang "awal kehidupan
itu terjadi" dan bak anjing budug lapar dihadapan seonggok taik angat lantas
bergegas melahap omong kosong orang semitik primitif yang tidak berbukti:
kehidupan itu diciptakan oleh Tuhan atau Allah.
Begitu juga tentang asal mula terjadinya alam semesta ini.
Sikap yang rasional, yang diambil antara lain oleh ateis, adalah terus berusaha
melakukan penelitian untuk mengetahui "bagaimana alam semesta ini terjadi".
Itulah yang dilakukan, antara lain, oleh ilmuwan di LHC. Atau, bagi yang bukan
ilmuwan untuk menunggu hasil penelitian para ilmuwan.
Sikap yang tidak rasional, yaitu sikap yang diambil antara lain oleh teis,
adalah belum apa-apa udah nyerah dihadapan pertanyaan tentang ""bagaimana alam
semesta ini terjadi"" dan bak anjing budug lapar dihadapan seonggok taik angat
lantas bergegas melahap omong kosong orang semitik primitif yang tidak berbukti:
alam semesta ini diciptakan oleh Tuhan atau Allah.
Agar jelas: agama semitik itu adalah penghambat fikiran, agama itu bikin mampet
otak manusia.
Web address:
http://www.sciencedaily.com/releases/2011/01/
110119100204.htm
More Asteroids Could Have Made Life's Ingredients
enlarge
This artist's concept uses hands to illustrate the left and right-handed
versions of the amino acid isovaline. (Credit: NASA/Mary Pat Hrybyk-Keith)
ScienceDaily (Jan. 19, 2011) A wider range of asteroids were capable of
creating the kind of amino acids used by life on Earth, according to new NASA
research.
Amino acids are used to build proteins, which are used by life to make
structures like hair and nails, and to speed up or regulate chemical reactions.
Amino acids come in two varieties that are mirror images of each other, like
your hands. Life on Earth uses the left-handed kind exclusively. Since life
based on right-handed amino acids would presumably work fine, scientists are
trying to find out why Earth-based life favored left-handed amino acids.
In March, 2009, researchers at NASA's Goddard Space Flight Center in Greenbelt,
Md., reported the discovery of an excess of the left-handed form of the amino
acid isovaline in samples of meteorites that came from carbon-rich asteroids.
This suggests that perhaps left-handed life got its start in space, where
conditions in asteroids favored the creation of left-handed amino acids.
Meteorite impacts could have supplied this material, enriched in left-handed
molecules, to Earth. The bias toward left-handedness would have been
perpetuated as this material was incorporated into emerging life.
In the new research, the team reports finding excess left-handed isovaline
(L-isovaline) in a much wider variety of carbon-rich meteorites. "This tells us
our initial discovery wasn't a fluke; that there really was something going on
in the asteroids where these meteorites came from that favors the creation of
left-handed amino acids," says Dr. Daniel Glavin of NASA Goddard. Glavin is
lead author of a paper about this research published online in Meteoritics and
Planetary Science January 17.
"This research builds on over a decade of work on excesses of left-handed
isovaline in carbon-rich meteorites," said Dr. Jason Dworkin of NASA Goddard, a
co-author on the paper.
"Initially, John Cronin and Sandra Pizzarello of Arizona State University
showed a small but significant excess of L-isovaline in two CM2 meteorites.
Last year we showed that L-isovaline excesses appear to track with the history
of hot water on the asteroid from which the meteorites came. In this work we
have studied some exceptionally rare meteorites which witnessed large amounts
of water on the asteroid. We were gratified that the meteorites in this study
corroborate our hypothesis," explained Dworkin.
L-isovaline excesses in these additional water-altered type 1 meteorites (i.e.
CM1 and CR1) suggest that extra left-handed amino acids in water-altered
meteorites are much more common than previously thought, according to Glavin.
Now the question is what process creates extra left-handed amino acids. There
are several options, and it will take more research to identify the specific
reaction, according to the team.
However, "liquid water seems to be the key," notes Glavin. "We can tell how
much these asteroids were altered by liquid water by analyzing the minerals
their meteorites contain. The more these asteroids were altered, the greater
the excess L-isovaline we found. This indicates some process involving liquid
water favors the creation of left-handed amino acids."
Another clue comes from the total amount of isovaline found in each meteorite.
"In the meteorites with the largest left-handed excess, we find about 1,000
times less isovaline than in meteorites with a small or non-detectable
left-handed excess. This tells us that to get the excess, you need to use up or
destroy the amino acid, so the process is a double-edged sword," says Glavin.
Whatever it may be, the water-alteration process only amplifies a small
existing left-handed excess, it does not create the bias, according to Glavin.
Something in the pre-solar nebula (a vast cloud of gas and dust from which our
solar system, and probably many others, were born) created a small initial bias
toward L-isovaline and presumably many other left-handed amino acids as well.
One possibility is radiation. Space is filled with objects like massive stars,
neutron stars, and black holes, just to name a few, that produce many kinds of
radiation. It's possible that the radiation encountered by our solar system in
its youth made left-handed amino acids slightly more likely to be created, or
right-handed amino acids a bit more likely to be destroyed, according to Glavin.
It's also possible that other young solar systems encountered different
radiation that favored right-handed amino acids. If life emerged in one of
these solar systems, perhaps the bias toward right-handed amino acids would be
built in just as it may have been for left-handed amino acids here, according
to Glavin.
The research was funded by the NASA Astrobiology Institute (NAI), which is
administered by NASA's Ames Research Center in Moffett Field, Calif.; the NASA
Cosmochemistry program, the Goddard Center for Astrobiology, and the NASA Post
Doctoral Fellowship program. The team includes Glavin, Dworkin, Dr. Michael
Callahan, and Dr. Jamie Elsila of NASA Goddard.
Email or share this story:
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Story Source:
The above story is reprinted (with editorial adaptations by ScienceDaily
staff) from materials provided by NASA.
Journal Reference:
1. Daniel P. Glavin, Michael P. Callahan, Jason P. Dworkin, Jamie E. Elsila.
The effects of parent body processes on amino acids in carbonaceous chondrites.
Meteoritics & Planetary Science, 2010; 45 (12): 1948 DOI:
10.1111/j.1945-5100.2010.01132.x
Need to cite this story in your essay, paper, or report? Use one of the
following formats:
APA
MLA
NASA (2011, January 19). More asteroids could have made life's ingredients.
ScienceDaily. Retrieved January 19, 2011, from http://www.sciencedaily.com
/releases/2011/01/110119100204.htm
Note: If no author is given, the source is cited instead.
Disclaimer: Views expressed in this article do not necessarily reflect those of
ScienceDaily or its staff.
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