Sun's Movement Through Milky Way... Comets Hurtling...Life Extinctions

Science Daily ^ | 5-2-2008 | Cardiff University

[blam]

Sun's Movement Through Milky Way Regularly Sends Comets Hurtling, Coinciding With Mass Life Extinctions

A large body of scientific evidence now exists that support the hypothesis that a major asteroid or comet impact occurred in the Caribbean region at the boundary of the Cretaceous and Tertiary periods in Earth's geologic history. Such an impact is suspected to be responsible for the mass extinction of many floral and faunal species, including the large dinosaurs, that marked the end of the Cretaceous period. (Credit: Art by Don Davis / Courtesy of NASA)

ScienceDaily (May 2, 2008) — The sun's movement through the Milky Way regularly sends comets hurtling into the inner solar system -- coinciding with mass life extinctions on earth, a new study claims. The study suggests a link between comet bombardment and the movement through the galaxy.

Scientists at the Cardiff Centre for Astrobiology built a computer model of our solar system's movement and found that it "bounces" up and down through the plane of the galaxy. As we pass through the densest part of the plane, gravitational forces from the surrounding giant gas and dust clouds dislodge comets from their paths. The comets plunge into the solar system, some of them colliding with the earth.

The Cardiff team found that we pass through the galactic plane every 35 to 40 million years, increasing the chances of a comet collision tenfold. Evidence from craters on Earth also suggests we suffer more collisions approximately 36 million years. Professor William Napier, of the Cardiff Centre for Astrobiology, said: "It's a beautiful match between what we see on the ground and what is expected from the galactic record."

The periods of comet bombardment also coincide with mass extinctions, such as that of the dinosaurs 65 million years ago. Our present position in the galaxy suggests we are now very close to another such period.

While the "bounce" effect may have been bad news for dinosaurs, it may also have helped life to spread. The scientists suggest the impact may have thrown debris containing micro-organisms out into space and across the universe.

Centre director Professor Chandra Wickramasinghe said: "This is a seminal paper which places the comet-life interaction on a firm basis, and shows a mechanism by which life can be dispersed on a galactic scale."

The paper, by Professor Napier and Dr Janaki Wickramasinghe, is to be published in the Monthly Notices of the Royal Astronomical Society.

Adapted from materials provided by Cardiff University, via EurekAlert!, a service of AAAS.

[GourmetDan]

"Ah, but the nuances come later. You are aware that there are differences between being locked in an accelerating spaceship, and being in a gravitational field, I’m sure. Similar issues occur with rotating reference frames."

Ah yes. Now we are left with allusions to undefined 'nuances'. I think we have found who has the reading comprehension problem.

When Einstein stated that a set of physical laws could be formulated for all reference frames, that includes gravitational fields and accelerating spaceships. And when Hoyle stated that you cannot say that Copernican theory is 'right' and Ptolemaic theory is 'wrong' *in any meaningful physical sense*, he meant exactly that. No meaningful physical sense means no meaningful physical sense. That leaves only philosophy and belief.

We could discuss nuances forever. Such as the nuances around whether GR was developed to reconcile the 'fact' that we 'know' that the earth moves while lacking evidence for such motion? (M-M null result) Or nuances like the continued lack of evidence for the motion of the earth, like Airey's Failure.

And nuances like centrifugal force and Coriolis effects arising naturally in a rotating universe but defined as 'fictitious' forces in GR?

Or how about nuances like the failure of Gravity Probe B's effort to find evidence of 'frame-dragging' (which was one of it's main goals) because of 'un-modeled' effects?

But, the fact remains that both Einstein and Hoyle understood what continues to escape you.

[GourmetDan]

"As a practical matter, it takes a lot less energy to rotate an object, than to rotate the entire universe around it."

Which is a philosophical preference wrt the origins of the universe that has nothing to do w/ Occam's Razor.

http://en.wikipedia.org/wiki/Occam's_Razor

"Thus the popular rephrasing of the razor - that "the simplest explanation is the best one" - fails to capture the gist of the reason behind it, in that it conflates a rigorous notion of simplicity and ease of human comprehension. The two are obviously correlated, but hardly equivalent."

[PreciousLiberty]

’ Which is a philosophical preference wrt the origins of the universe that has nothing to do w/ Occam’s Razor.

http://en.wikipedia.org/wiki/Occam’s_Razor

“Thus the popular rephrasing of the razor - that “the simplest explanation is the best one” - fails to capture the gist of the reason behind it, in that it conflates a rigorous notion of simplicity and ease of human comprehension. The two are obviously correlated, but hardly equivalent.”’

Which misses the point that the simplest explanation that fits the facts is very often correct, and a good starting point. For any observed phenomenon there is an infinite manifold of (excessively) complex explanations. Read about epicycles sometime, for example.

[GourmetDan]

"Which misses the point that the simplest explanation that fits the facts is very often correct, and a good starting point. For any observed phenomenon there is an infinite manifold of (excessively) complex explanations."

As already explained, the explanation requiring the fewest assumption is a rotating universe and a stable earth. This fits the observed facts.

"Read about epicycles sometime, for example."

Both Einstein and Hoyle knew that epicycles do not apply to the argument in a GR model. That was inherent in their statements and you should have been able to comprehend that.

Once again we see that it is you who is woefully uninformed.

[PreciousLiberty]

“Once again we see that it is you who is woefully uninformed.”

Sure, pal. Have a good one, and enjoy your rotating universe.

heh