ريتشارد دوكنز's Blog, page 556
February 19, 2016
Exoplanet Census Suggests Earth Is Special after All
Photo credit: NASA/ESA/ESO
By Shannon Hall
More than 400 years ago Renaissance scientist Nicolaus Copernicus reduced us to near nothingness by showing that our planet is not the center of the solar system. With every subsequent scientific revolution, most other privileged positions in the universe humans might have held dear have been further degraded, revealing the cold truth that our species is the smallest of specks on a speck of a planet, cosmologically speaking. A new calculation of exoplanets suggests that Earth is just one out of a likely 700 million trillion terrestrial planets in the entire observable universe. But the average age of these planets—well above Earth’s age—and their typical locations—in galaxies vastly unlike the Milky Way—just might turn the Copernican principle on its head.
Astronomer Erik Zackrisson from Uppsala University and his colleagues created a cosmic compendium of all the terrestrial exoplanets likely to exist throughout the observable universe, based on the rocky worlds astronomers have found so far. In a powerful computer simulation, they first created their own mini universe containing models of the earliest galaxies. Then they unleashed the laws of physics—as close as scientists understand them—that describe how galaxies grow, how stars evolve and how planets come to be. Finally, they fast-forwarded through 13.8 billion years of cosmic history. Their results, published to the preprint server arXiv and submitted to The Astrophysical Journal, provide a tantalizing trove of probable exoplanet statistics that helps astronomers understand our place in the universe. “It’s kind of mind-boggling that we’re actually at a point where we can begin to do this,” says co-author Andrew Benson from the Carnegie Observatories in California. Until recently, he says, so few exoplanets were known that reasonable extrapolations to the rest of the universe were impossible. Still, his team’s findings are a preliminary guess at what the cosmos might hold. “It’s certainly the case that there are a lot of uncertainties in a calculation like this. Our knowledge of all of these pieces is imperfect,” he adds.
Take exoplanets as an example. NASA’s Kepler space telescope is arguably one of the world’s best planet hunters, but it uses a method so challenging that it is often compared with looking across thousands of kilometers to see a firefly buzzing around a brilliant searchlight. Because the telescope looks for subtle dimming in a star’s light from planets crossing in front of it, Kepler has an easier time spotting massive planets orbiting close to their stars. Thus, the catalogue of planets Kepler has found lean heavily toward these types, and smaller, farther-out planets are underrepresented, leaving our knowledge of planetary systems incomplete. Astronomers do use other techniques to search for smaller planets orbiting at farther distances, but these methods are still relatively new and have not yet found nearly as many worlds as Kepler. In addition, “everything we know about exoplanets is from a very small patch in our galaxy,” Zackrisson says, within which most stars are pretty similar to one another in terms of how many heavy elements they contain and other characteristics. The team had to extrapolate in order to guess how planets might form around stars with fewer heavy elements, such as those found in small galaxies or the early universe.
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What sparked the Cambrian explosion?
Photo credit: John Sibbick/Natural History Museum
By Douglas Fox
A series of dark, craggy pinnacles rises 80 metres above the grassy plains of Namibia. The peaks call to mind something ancient — the burial mounds of past civilizations or the tips of vast pyramids buried by the ages.
The stone formations are indeed monuments of a faded empire, but not from anything hewn by human hands. They are pinnacle reefs, built by cyanobacteria on the shallow sea floor 543 million years ago, during a time known as the Ediacaran period. The ancient world occupied by these reefs was truly alien. The oceans held so little oxygen that modern fish would quickly founder and die there. A gooey mat of microbes covered the sea floor at the time, and on that blanket lived a variety of enigmatic animals whose bodies resembled thin, quilted pillows. Most were stationary, but a few meandered blindly over the slime, grazing on the microbes. Animal life at this point was simple, and there were no predators. But an evolutionary storm would soon upend this quiet world.
Within several million years, this simple ecosystem would disappear, and give way to a world ruled by highly mobile animals that sported modern anatomical features. The Cambrian explosion, as it is called, produced arthropods with legs and compound eyes, worms with feathery gills and swift predators that could crush prey in tooth-rimmed jaws. Biologists have argued for decades over what ignited this evolutionary burst. Some think that a steep rise in oxygen sparked the change, whereas others say that it sprang from the development of some key evolutionary innovation, such as vision. The precise cause has remained elusive, in part because so little is known about the physical and chemical environment at that time.
But over the past several years, discoveries have begun to yield some tantalizing clues about the end of the Ediacaran. Evidence gathered from the Namibian reefs and other sites suggests that earlier theories were overly simplistic — that the Cambrian explosion actually emerged out of a complex interplay between small environmental changes that triggered major evolutionary developments.
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The five most common misunderstandings about evolution
Photo credit: DaniRevi/pixabay
By Paula Kover
Given its huge success in describing the natural world for the past 150 years, the theory of evolution is remarkably misunderstood. In a recent episode of the Australian series of “I’m a Celebrity Get Me Out of Here”, former cricket star Shane Warne questioned the theory – asking “if humans evolved from monkeys, why haven’t today’s monkeys evolved”?
Similarly, a head teacher from a primary school in the UK recently stated that evolution is a theory rather than a fact. This is despite the fact that children in the UK start learning about evolution in Year 6 (ten to 11-year-olds), and have further lessons throughout high school. While the theory of evolution is well accepted in the UK compared with the rest of the world, a survey in 2005 indicated that more than 20% of the country’s population was not sure about it, or did not accept it.
In contrast, there are not many people questioning the theory of relativity, or studies on the acceptance of the theory of relativity; possibly reflecting an acceptance that this is a matter for physicists to settle. Many studies have tried to determine why evolution is questioned so often by the general public, despite complete acceptance by scientists. Although no clear answer has been found, I suspect the common misconceptions described below have something to do with it.
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Zika Virus Rumors and Theories That You Should Doubt
Photo credit: Victor Moriyama/Getty Images
By Donald G. McNeil Jr.
Although there is no absolute proof that the Zika virus is behind the surge in microcephaly in Brazil and outbreaks of Guillain-Barré syndrome in six countries, the world’s leading health authorities are close to certain that it is.
“With each passing day, the evidence that it is the cause mounts,” Dr. Thomas R. Frieden, director of the Centers for Disease Control and Prevention, said recently.
Dr. Bruce Aylward, who is leading the World Health Organization’s response, said on Friday: “At this time, the virus is considered guilty until proven innocent.”
Many rumors blaming other potential causes have arisen, and the authorities have worked hard to debunk them. Here is a look at the most prominent theories making the rounds on social media, along with responses from scientists.
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More than an ornament: Iran’s ‘female statesmen’ and elections
Photo credit: AFP/Getty Images
By Farnoosh Amirshahi
Traditionalist clerics often invoke a masculine term to discourage women from running for political office in Iran. While the question of gender isn’t addressed in Iran’s electoral laws, candidates wishing to participate in the Iranian political scene must be considered “Rajol-e-siasi,” or statesmen. If the political arena is legally defined as the purview of statesmen, women have no business entering it, conservatives argue.
This paradox helps explain the status of female politicians in a system where only 49 women have served in parliament since 1979, accounting for only 3% of all parliamentary seats. To maintain any presence at all, female lawmakers must reconcile conservative Islamic values with the social advancement of their gender.
Even if they possess an immaculate political and theological pedigree, female politicians struggle to advance their agendas without altering traditional women’s roles as defined by male Islamic jurists. When addressing basic issues such as workforce participation, successful female lawmakers like conservative MP Soheila Jelodarzadeh take care to only support part-time employment, prioritizing women’s roles as mothers and homemaker.
Outspoken female parliamentarians from across Iran’s political spectrum have been ostracized, even jailed, for their overly progressive views. Others have maintained a merely ornamental presence in politics, voting along factional lines and against their own interests as women.
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The heat goes on: Earth sets 9th straight monthly record
Photo credit: The National Oceanic and Atmospheric Administration via AP
By Seth Borenstein
The January figures are in, and Earth’s string of hottest-months-on-record has now reached nine in a row. But NASA said January stood out: The temperature was above normal by the highest margin of any month on record.
And January set another record: Arctic sea ice reached its lowest point for that ice-building winter month.
NASA said January 2016 was 2.03 degrees Fahrenheit (1.13 degrees Celsius) above normal. The National Oceanic and Atmospheric Administration, which calculates temperatures differently, said last month was 1.87 degrees (1.04 degrees Celsius), which is the second biggest margin in history. NOAA said the greatest was this past December.
January’s average global temperature was a record 55.5 degrees Fahrenheit (13 degrees Celsius), easily beating the old January record set in 2007, according to NOAA. Records go back to 1880.
There were colder-than-normal patches in parts of the United States, Europe and Asia in January, but they were overwhelmed by incredible “off our chart” warming in the Arctic region, according to NOAA climate scientist Jessica Blunden. Siberia, northwest Canada, and a lot of Alaska were at least 9 degrees Fahrenheit warmer than normal, she said.
That heat was why there was record low sea ice in the Arctic for this time of year, when sea ice grows, Blunden said.
January Arctic sea ice averaged only 5.2 million square miles in January, which is 90,000 square miles below the previous record set in 2011, according to the National Snow and Ice Data Center. It’s also 402,000 square miles—about the size of Texas and New Mexico, combined—less than the 30-year normal.
The string of nine consecutive record hot months matches June 1997 to February 1998, which was the last time Earth had a large El Nino. It is still behind the 10 straight months of record heat in 1944, Blunden said. It’s likely we’ll tie that record in February, she said.
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February 18, 2016
Asteroids Fizzle Out When Approaching The Sun
Photo credit:
Asteroid Ida. NASA/JPL
Asteroid impacts are a real and present danger to Earth and our survival, but just how much? To find out, an international team of researchers set out to construct a state-of-the-art model of all near-Earth objects (NEOs) in the Solar System, and they discovered that they are being destroyed further from the Sun than previously thought – although still pretty close.
Secret Language Of The Mantis Shrimp Could Lead To New Type Of Optical Material
Photo credit:
These crustaceans like to keep their conversations private. Nick Utchin/Shutterstock
It’s easy to appreciate how incredible the biological engineering of a mantis shrimp is. Whether it’s the “smasher” or “spearer” variant, this unusual, persistently hostile critter constantly surprises researchers. Just last year, several studies revealed that it can communicate using patterns of light; now, a study published in the journal Scientific Reports has discovered how the mantis shrimp is able to produce such complex patterns of light.
Big Bang Afterglow Boosts Distant Black Hole Jet
Photo credit:
B3 0727+409 as seen in X-ray by Chandra. NASA/CXC/ISAS/A.Simionescu et al,
A lucky discovery has allowed astronomers to probe the very early universe. The collision between light from the cosmic microwave background and the jet from a supermassive black hole has made the jet 150 times brighter, revealing some of its features from when it was emitted over 11 billion years ago.
Death Valley May Be In For A Rare “Super Bloom”
Photo credit:
Image from the "super bloom" in 2005. Death Valley National Park/Facebook
The name “Death Valley” creates a certain image in your mind: dust, a ram's skull, maybe some tumble weed, more dust. However, a “super bloom” of wildflowers has been predicted in the area that is known for being the hottest and driest place in North America.
Since mid-January, the notoriously barren eastern California desert has seen a spring of life, with park officials hoping the best is yet to come.
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