Science & TechnologyS


Alarm Clock

Controversially, physicist argues time is real

Clara Moskowitz
LiveScience
Fri, 26 Apr 2013 10:07 UTC
Time
© Shutterstock/Kim D. FrenchMost physicists think time is a subjective illusion, but what if time is real?
New York - Is time real, or the ultimate illusion?

Most physicists would say the latter, but Lee Smolin challenges this orthodoxy in his new book, Time Reborn (Houghton Mifflin Harcourt, April 2013), which he discussed here Wednesday (April 24) at the Rubin Museum of Art.

In a conversation with Duke University neuroscientist Warren Meck, theoretical physicist Smolin, who's based at Canada's Perimeter Institute for Theoretical Physics, argued for the controversial idea that time is real. "Time is paramount," he said, "and the experience we all have of reality being in the present moment is not an illusion, but the deepest clue we have to the fundamental nature of reality."

Smolin said he hadn't come to this concept lightly. He started out thinking, as most physicists do, that time is subjective and illusory. According to Albert Einstein's theory of general relativity, time is just another dimension in space, traversable in either direction, and our human perception of moments passing steadily and sequentially is all in our heads.

Over time, though, Smolin became convinced not only that time was real, but that this notion could be the key to understanding the laws of nature.

"If laws are outside of time, then they're inexplicable," he said. "If law just simply is, there's no explanation. If we want to understand law ... then law must evolve, law must change, law must be subject to time. Law then emerges from time and is subject to time rather than the reverse."
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Meteor

NASA probe observes meteors colliding with Saturn's rings


sciencedaily.com
Thu, 25 Apr 2013 16:31 UTC
Apr. 25, 2013 - NASA's Cassini spacecraft has provided the first direct evidence of small meteoroids breaking into streams of rubble and crashing into Saturn's rings.

Image
© NASA/JPL-Caltech/Space Science Institute/CornellFive images of Saturn's rings, taken by NASA's Cassini spacecraft between 2009 and 2012, show clouds of material ejected from impacts of small objects into the rings.
These observations make Saturn's rings the only location besides Earth, the moon and Jupiter where scientists and amateur astronomers have been able to observe impacts as they occur. Studying the impact rate of meteoroids from outside the Saturnian system helps scientists understand how different planet systems in our solar system formed.

The solar system is full of small, speeding objects. These objects frequently pummel planetary bodies. The meteoroids at Saturn are estimated to range from about one-half inch to several yards (1 centimeter to several meters) in size. It took scientists years to distinguish tracks left by nine meteoroids in 2005, 2009 and 2012.

Details of the observations appear in a paper in the Thursday, April 25 edition of Science.
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Info

Earth's core 1,000 degrees hotter than expected

Elizabeth Howell
OurAmazingPlanet
Thu, 25 Apr 2013 13:01 UTC
Earth's Core
© NASAEarth has multiple layers: the crust, the mantle, the liquid outer core and the solid inner core.
Earth's internal engine is running about 1,000 degrees Celsius (about 1,800 degrees Fahrenheit) hotter than previously measured, providing a better explanation for how the planet generates a magnetic field, a new study has found.

A team of scientists has measured the melting point of iron at high precision in a laboratory, and then drew from that result to calculate the temperature at the boundary of Earth's inner and outer core - now estimated at 6,000 C (about 10,800 F). That's as hot as the surface of the sun.

The difference in temperature matters, because this explains how the Earth generates its magnetic field. The Earth has a solid inner core surrounded by a liquid outer core, which, in turn, has the solid, but flowing, mantle above it. There needs to be a 2,700-degree F (1,500 C) difference between the inner core and the mantle to spur "thermal movements" that - along with Earth's spin - create the magnetic field.

The previously measured core temperature didn't demonstrate enough of a differential, puzzling researchers for two decades. The new results are detailed in the April 26 issue of the journal Science.
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Fireball 3

Comet ISON could blast earth with weird meteor shower

Irene Klotz
Discovery
Tue, 23 Apr 2013 16:23 UTC
comet ison hubble
© NASA, ESA, J.-Y. Li (Planetary Science Institute), and the Hubble Comet ISON Imaging Science TeamThis NASA Hubble Space Telescope image of Comet C/2012 S1 (ISON) was photographed on April 10, when the comet was slightly closer than Jupiter's orbit at a distance of 386 million miles from the sun (394 million miles from Earth).
A small but incredibly bright comet heading toward the sun could do more than dazzle Earth's skies when it arrives later this year. Scientists say Comet ISON, already shedding dust at the prodigious rate of about 112,000 pounds per minute, could spark an unusual meteor shower.

Computer simulations predicting the location and movement of the comet's dust trail show Earth will be passing through the fine-grained stream around Jan. 12, 2014.

Some of the particles, which are smaller in diameter than a red blood cell, should be pushed back by the pressure of sunlight, allowing them to be captured by Earth's gravity when the planet plows through the largely invisible stream.
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Info

Early Earth's chlorine blown away by giant impacts

Erin Wayman
Science News
Wed, 24 Apr 2013 15:46 UTC
Asteroid
© Mopic/Shutterstock
Earthlings may owe a debt of gratitude to the enormous miniplanets that smashed into the planet it its youth. Such collisions might have knocked away much of the supply of chlorine concentrated on the planet's surface, geochemists propose. Had that loss not occurred, the world's oceans would have been too salty for complex life to thrive, they suggest.

The scenario may explain why Mars, which suffered fewer large impacts, may have more than twice as much chlorine as Earth does, the researchers report April 16 in Earth and Planetary Science Letters.

"The story seems to hang together pretty well," says James Brenan, a geologist at the University of Toronto who wasn't involved in the study. "Life, probably over a fairly long time, might have been able to adapt to this environment, though certainly things would be different than today."

One snag is that the idea is "a very difficult thing to test," says geochemist Ray Burgess of the University of Manchester in England.

The composition of ancient meteorites, which are remnants of the raw material that built the planets, indicates that Earth should have 10 times as much chlorine as it does. The missing chlorine has perplexed scientists for decades. In 1995, geochemist William McDonough suggested that chlorine was dragged to Earth's center by iron, nickel and other metals that formed the planet's core.
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Play

Video: NASA | SDO: Three years of the sun in three minutes

NASAexplorer
NASA/YouTube
Wed, 24 Apr 2013 14:18 UTC
In the three years since it first provided images of the sun in the spring of 2010, NASA's Solar Dynamics Observatory (SDO) has had virtually unbroken coverage of the sun's rise toward solar maximum, the peak of solar activity in its regular 11-year cycle. This video shows those three years of the sun at a pace of two images per day.

SDO's Atmospheric Imaging Assembly (AIA) captures a shot of the sun every 12 seconds in 10 different wavelengths. The images shown here are based on a wavelength of 171 Angstroms, which is in the extreme ultraviolet range and shows solar material at around 600,000 Kelvin. In this wavelength it is easy to see the sun's 25-day rotation as well as how solar activity has increased over three years.

During the course of the video, the sun subtly increases and decreases in apparent size. This is because the distance between the SDO spacecraft and the sun varies over time. The image is, however, remarkably consistent and stable despite the fact that SDO orbits the Earth at 6,876 miles per hour and the Earth orbits the sun at 67,062 miles per hour.

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Fireball 5

UCLA scientists devise new method to locate incoming meteoroid debris

April Flowers
RedOrbit
Wed, 24 Apr 2013 14:16 UTC
Asteroid
© Mopic/Shutterstock
Asteroids and other objects in our solar system collide often, but researchers are not always able to detect or track such impacts from Earth. This means that we are sometimes caught unaware by the "rogue debris" created by the impacts.

New research from the University of California, Los Angeles, has devised a method to monitor these types of collisions in interplanetary space. The team used a new method to determine the mass of magnetic clouds that result from the impacts. Nearly 30 years of observations of such collisions went into the findings published online in the journal Meteoritics and Planetary Science. The study could help researchers have a better understanding of how to locate incoming meteoroid debris that could endanger the Earth.

"The passage by the Earth earlier this year of the small asteroid 2012 DA14 and the explosion the same week of an even smaller asteroid in the atmosphere above central Russia remind us that while space is mostly empty, the objects that are orbiting the sun do occasionally collide with other orbiting bodies, and the energy released in such collisions can be catastrophic to the bodies involved," said Christopher T. Russell, a professor in UCLA's Department of Earth and Space Sciences.

"We have found a way by which we can monitor such collisions in space by identifying the magnetic signature produced in these collisions," he said. "While the colliding objects may be only tens to hundreds of feet across, the resulting magnetic signature can be hundreds of thousands of miles in width and be carried outward from the sun by the solar wind for millions of miles."
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Jupiter

Origin of Jupiter's water mystery solved: The massive 1994 comet bombardment


The Daily Galaxy
Wed, 24 Apr 2013 05:39 UTC
Jupiter
© European Space Agency
ESA's Herschel space observatory has solved a long-standing mystery as to the origin of water in the upper atmosphere of Jupiter, finding conclusive evidence that it was delivered by the dramatic impact of comet Shoemaker-Levy 9 in July 1994. During the spectacular week-long collision, a string of 21 comet fragments pounded into the southern hemisphere of Jupiter, leaving dark scars in the planet's atmosphere that persisted for several weeks.

The remarkable event was the first direct observation of an extraterrestrial collision in the Solar System. It was followed worldwide by amateur and professional astronomers with many ground-based telescopes and the NASA/ESA Hubble Space Telescope.

ESA's Infrared Space Observatory was launched in 1995 and was the first to detect and study water in Jupiter's upper atmosphere. It was widely speculated that comet Shoemaker-Levy 9 may have been the origin of this water, but direct proof was missing.
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Comet

First glimpse of 'comet of the century': Hubble gets snaps ISON that astronomers hope will amaze the world

Mark Prigg
The Daily Mail UK
Tue, 23 Apr 2013 04:03 UTC
Comet could shine brighter than Venus or even the full moon in November

Photographed on April 10, when it was 394 million miles from Earth

The Hubble Space Telescope has given astronomers their clearest view yet of Comet ISON, which experts believe could light up the sky in a breathtaking display later this year.

The image of Comet C/2012 S1 (ISON) was photographed on April 10, when the comet was slightly closer than Jupiter's orbit at a distance of 386 million miles from the Sun, and 394 million miles from Earth.

Experts believe it will get dramatically brighter as it swings around the sun in late November, with some claiming the comet could shine brighter than Venus or even the full moon.
Image
Comet C/ISON was imaged with the Hubble Space telescope on April 10 using the Wide Field Camera 3, when the comet was 394 million miles from Earth
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Info

Australia wasn't found by accident, study suggests

Stephanie Pappas
LiveScience
Tue, 23 Apr 2013 16:01 UTC
Australia
© NASAThe Australian continent from NASA's "Blue Marble" satellite imagery of Earth.
Australia's colonization may have been an organized affair rather than an accident, a new analysis suggests.

Some 50,000 years ago, aboriginal human settlers arrived on the continent, but how many people it took to found Australia's population is unknown. The new study, published Tuesday (April 23) in the journal Proceedings of the Royal Society B, suggests that about 1,000 to 3,000 individuals originally landed on Australia's shores.

"This is largely speculative, but I think this suggests something more than accidental colonization by a small group on a raft of vegetation or other unplanned voyage," study researcher Alan Williams, a doctoral candidate at The Australian National University, wrote in an email. "For me, this suggests a deliberate attempt at exploration (if not migration) more akin to those we see in the recent past from Hawaii and other Pacific islands."
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