Milky Way Appears to be Void of Dark Matter



Taken from: http://www.dailygalaxy.com/my_weblog/2012/04/milky-way-appears-to-be-void-of-dark-matter-the-mystery-of-dark-matter-deepens-a-new-solution-for-th.html

Milky Way Appears to be Void of Dark Matter --"The Mystery of Dark Matter Deepens --A New Solution for the Missing Mass Problem Must be Found."

The most accurate study so far of the motions of stars in the Milky Way has found no evidence for dark matter in a large volume around the Sun. According to widely accepted theories, the solar neighbourhood was expected to be filled with dark matter, a mysterious invisible substance that can only be detected indirectly by the gravitational force it exerts.
 

         

 

A new study by a team of astronomers in Chile has found that these theories just do not fit the observational facts. This may mean that attempts to directly detect dark matter particles on Earth are unlikely to be successful. A team using the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory, along with other telescopes, has mapped the motions of more than 400 stars up to 13 000 light-years from the Sun. From this new data they have calculated the mass of material in the vicinity of the Sun, in a volume four times larger than ever considered before.
“The amount of mass that we derive matches very well with what we see — stars, dust and gas — in the region around the Sun,” says team leader Christian Moni Bidin (Departamento de Astronomía, Universidad de Concepción, Chile). “But this leaves no room for the extra material — dark matter — that we were expecting. Our calculations show that it should have shown up very clearly in our measurements. But it was just not there!”
Dark matter is a mysterious substance that cannot be seen, but shows itself by its gravitational attraction for the material around it. This extra ingredient in the cosmos was originally suggested to explain why the outer parts of galaxies, including our own Milky Way, rotated so quickly, but dark matter now also forms an essential component of theories of how galaxies formed and evolved.
According to current theories dark matter is estimated to constitute 83% of the matter in the Universe with the remaining 17% in the form of normal matter. A much larger amount of dark energy also seems present in the Universe, but is not expected to affect the motions of the stars within the Milky Way. All attempts so far to detect dark matter in laboratories on Earth have failed.
By very carefully measuring the motions of many stars, particularly those away from the plane of the Milky Way, the team could work backwards to deduce how much matter is present. The motions are a result of the mutual gravitational attraction of all the material, whether normal matter such as stars, or dark matter.
Astronomers’ existing models of how galaxies form and rotate suggest that the Milky Way is surrounded by a halo of dark matter. They are not able to precisely predict what shape this halo takes, but they do expect to find significant amounts in the region around the Sun. But only very unlikely shapes for the dark matter halo — such as a highly elongated form — can explain the lack of dark matter uncovered in the new study.
The new results also mean that attempts to detect dark matter on Earth by trying to spot the rare interactions between dark matter particles and “normal” matter are unlikely to be successful.
“Despite the new results, the Milky Way certainly rotates much faster than the visible matter alone can account for. So, if dark matter is not present where we expected it, a new solution for the missing mass problem must be found. Our results contradict the currently accepted models. The mystery of dark matter has just become even more mysterious. Future surveys, such as the ESA Gaia mission, will be crucial to move beyond this point.” concludes Christian Moni Bidin.
The Daily Galaxy via ESO

Science Increasingly Makes the Case for God

The odds of life existing on another planet grow ever longer. Intelligent design, anyone?

                                

              

By

Eric Metaxas

Dec. 25, 2014 4:56 p.m. ET

8055 COMMENTS

In 1966 Time magazine ran a cover story asking: Is God Dead? Many have accepted the cultural narrative that he’s obsolete—that as science progresses, there is less need for a “God” to explain the universe. Yet it turns out that the rumors of God’s death were premature. More amazing is that the relatively recent case for his existence comes from a surprising place—science itself.
Here’s the story: The same year Time featured the now-famous headline, the astronomer Carl Sagan announced that there were two important criteria for a planet to support life: The right kind of star, and a planet the right distance from that star. Given the roughly octillion—1 followed by 27 zeros—planets in the universe, there should have been about septillion—1 followed by 24 zeros—planets capable of supporting life.
With such spectacular odds, the Search for Extraterrestrial Intelligence, a large, expensive collection of private and publicly funded projects launched in the 1960s, was sure to turn up something soon. Scientists listened with a vast radio telescopic network for signals that resembled coded intelligence and were not merely random. But as years passed, the silence from the rest of the universe was deafening. Congress defunded SETI in 1993, but the search continues with private funds. As of 2014, researchers have discovered precisely bubkis—0 followed by nothing.
What happened? As our knowledge of the universe increased, it became clear that there were far more factors necessary for life than Sagan supposed. His two parameters grew to 10 and then 20 and then 50, and so the number of potentially life-supporting planets decreased accordingly. The number dropped to a few thousand planets and kept on plummeting.
Even SETI proponents acknowledged the problem. Peter Schenkel wrote in a 2006 piece for Skeptical Inquirer magazine: “In light of new findings and insights, it seems appropriate to put excessive euphoria to rest . . . . We should quietly admit that the early estimates . . . may no longer be tenable.”
As factors continued to be discovered, the number of possible planets hit zero, and kept going. In other words, the odds turned against any planet in the universe supporting life, including this one. Probability said that even we shouldn’t be here.
Today there are more than 200 known parameters necessary for a planet to support life—every single one of which must be perfectly met, or the whole thing falls apart. Without a massive planet like Jupiter nearby, whose gravity will draw away asteroids, a thousand times as many would hit Earth’s surface. The odds against life in the universe are simply astonishing.
Yet here we are, not only existing, but talking about existing. What can account for it? Can every one of those many parameters have been perfect by accident? At what point is it fair to admit that science suggests that we cannot be the result of random forces? Doesn’t assuming that an intelligence created these perfect conditions require far less faith than believing that a life-sustaining Earth just happened to beat the inconceivable odds to come into being?
There’s more. The fine-tuning necessary for life to exist on a planet is nothing compared with the fine-tuning required for the universe to exist at all. For example, astrophysicists now know that the values of the four fundamental forces—gravity, the electromagnetic force, and the “strong” and “weak” nuclear forces—were determined less than one millionth of a second after the big bang. Alter any one value and the universe could not exist. For instance, if the ratio between the nuclear strong force and the electromagnetic force had been off by the tiniest fraction of the tiniest fraction—by even one part in 100,000,000,000,000,000—then no stars could have ever formed at all. Feel free to gulp.
Multiply that single parameter by all the other necessary conditions, and the odds against the universe existing are so heart-stoppingly astronomical that the notion that it all “just happened” defies common sense. It would be like tossing a coin and having it come up heads 10 quintillion times in a row. Really?
Fred Hoyle, the astronomer who coined the term “big bang,” said that his atheism was “greatly shaken” at these developments. He later wrote that “a common-sense interpretation of the facts suggests that a super-intellect has monkeyed with the physics, as well as with chemistry and biology . . . . The numbers one calculates from the facts seem to me so overwhelming as to put this conclusion almost beyond question.”
Theoretical physicist Paul Davies has said that “the appearance of design is overwhelming” and Oxford professor Dr. John Lennox has said “the more we get to know about our universe, the more the hypothesis that there is a Creator . . . gains in credibility as the best explanation of why we are here.”
The greatest miracle of all time, without any close seconds, is the universe. It is the miracle of all miracles, one that ineluctably points with the combined brightness of every star to something—or Someone—beyond itself.
Mr. Metaxas is the author, most recently, of “Miracles: What They Are, Why They Happen, and How They Can Change Your Life” ( Dutton Adult, 2014).

Correction
An earlier version understated the number of zeroes in an octillion and a septillion.

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Taken from: http://www.wsj.com/articles/eric-metaxas-science-increasingly-makes-the-case-for-god-1419544568