rationality and randomness http://awmitchell.posterous.com a personal blog of eclectic interests posterous.com Wed, 04 Nov 2009 13:31:07 -0800 Monbiot.com » Death Denial http://awmitchell.posterous.com/monbiotcom-death-denial http://awmitchell.posterous.com/monbiotcom-death-denial
There is no point in denying it: we’re losing. Climate change denial is spreading like a contagious disease. It exists in a sphere which cannot be reached by evidence or reasoned argument; any attempt to draw attention to scientific findings is greeted with furious invective. This sphere is expanding with astonishing speed.

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http://posterous.com/images/profile/missing-user-75.png http://posterous.com/users/4aQUIzR5baEN Andrew Mitchell awmitchell Andrew Mitchell
Sun, 01 Nov 2009 12:15:08 -0800 A crustacean eye that rivals the best optical equipment - "Go Evolution" http://awmitchell.posterous.com/a-crustacean-eye-that-rivals-the-best-optical http://awmitchell.posterous.com/a-crustacean-eye-that-rivals-the-best-optical

Normally, such a structure should still perform poorly over the entire visible range. What makes the structure work is that the tubes are made of membranes containing molecules that also have a refractive index that differs depending on the orientation of the light field. Now, we have four different refractive indexes: two associated with the form birefringence and two associated with the membranes. All four of them vary depending on the color of the light coming down the tubes. The form birefringence changes in just the right way to compensate the changes due to the membrane, providing a quarter waveplate that works well across the entire visible spectrum.

How good is this? A simple quarter waveplate made from a piece of quartz is accurate to within about ±20 degrees over the entire visible range—this is on the bad side of absolute junk. A quarter waveplate that makes use of form birefringence for better performance clocks in at around ±9 degrees. R8 beats this by a factor of three with a variation of just ±2.7 degrees over the visible range.

All I have to say at this point is: go evolution.

Contrary to the author's statement this research is, of course, evidence of Intelligent Desgin. How could 'evolution' (random change over time) result in something so complex?

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http://posterous.com/images/profile/missing-user-75.png http://posterous.com/users/4aQUIzR5baEN Andrew Mitchell awmitchell Andrew Mitchell
Tue, 13 Oct 2009 23:24:49 -0700 Monkeys Fall Into the Uncanny Valley, Just Like Humans | Wired Science http://awmitchell.posterous.com/monkeys-fall-into-the-uncanny-valley-just-lik http://awmitchell.posterous.com/monkeys-fall-into-the-uncanny-valley-just-lik
Monkeys are freaked out by almost-but-not-quite-real depictions of themselves. That tendency is well documented in humans, but has never before been seen in another species.

This interesting item shows a pyscological similarity between macaque monkeys and humans. Yet more evidence that we share evolutionary roots.

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Mon, 21 Sep 2009 14:45:19 -0700 Brilliant 360-Degree Panorama of the Milky Way http://awmitchell.posterous.com/brilliant-360-degree-panorama-of-the-milky-wa-1 http://awmitchell.posterous.com/brilliant-360-degree-panorama-of-the-milky-wa-1
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Mon, 21 Sep 2009 14:29:41 -0700 Second law of thermodynamics "broken" http://awmitchell.posterous.com/second-law-of-thermodynamics-broken http://awmitchell.posterous.com/second-law-of-thermodynamics-broken

Physicists knew that at atomic scales over very short periods of time, statistical mechanics is pushed beyond its limit, and the second law does not apply. Put another way, situations that break the second law become much more probable.

But the new experiment probed the uncertain middle ground between extremely small-scale systems and macroscopic systems and showed that the second law can also be consistently broken at micron scale, over time periods of up to two seconds.

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http://posterous.com/images/profile/missing-user-75.png http://posterous.com/users/4aQUIzR5baEN Andrew Mitchell awmitchell Andrew Mitchell
Mon, 21 Sep 2009 13:53:00 -0700 Scanning Dead Salmon in fMRI Machine Highlights Risk of Red Herrings http://awmitchell.posterous.com/scanning-dead-salmon-in-fmri-machine-highligh-0 http://awmitchell.posterous.com/scanning-dead-salmon-in-fmri-machine-highligh-0

Some researchers have created some fMRI images which, at first glance, show that a dead salmon had a brain response when asked to interpret images of human emotion. Funny? Hell yeah! But instructive also.

Bennett’s point is that a suite of methods known as multiple comparisons correction can allow researchers to maintain most of their statistical power while keeping the danger of false positives at bay.

The work highlights that brain science is highly data-driven and statistical now. Although the visualizations — usually some orangey spots on an otherwise dark brain scan — seem simple, the data collection and interpretation that go into producing them is intense.

Vul, who published a controversial paper earlier this year that was critical of some statistical methods used in the field, said he appreciated that Bennett was also trying to do some “internal policing” to make fMRI practitioners’ methods as rigorous as possible.

Unfortunately...

Bennett’s paper has been turned down by several publications, but a poster on the work received an appreciative audience at the Human Brain Mapping conference earlier this summer. Neuroscience researchers have been forwarding it to each other for weeks.

via wired.com and thanks to bfchirpy's blog for the link to this item.

It's distressing that publications continue to have a bias towards papers with positive results. Negative results, including false positives, can be even more instructive. On the flip side, the informal networks are spreading the story anyway.

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http://posterous.com/images/profile/missing-user-75.png http://posterous.com/users/4aQUIzR5baEN Andrew Mitchell awmitchell Andrew Mitchell
Wed, 16 Sep 2009 15:14:03 -0700 The Earth's Great Oxidation Event may have ended in a big dip - Ars Technica http://awmitchell.posterous.com/the-earths-great-oxidation-event-may-have-end http://awmitchell.posterous.com/the-earths-great-oxidation-event-may-have-end
The rise of oxygen, which altered the planet's atmosphere and enabled multicellular life, may not have come as two large bursts, as has been widely held, but rather as several "whiffs." That is the provocative conclusion of a study of chromium isotopes in ancient sedimentary rocks published in Nature. A team of geochemists led by Robert Frei of the University of Copenhagen, Denmark, found that oxygen took a few twists and turns before reaching its present level.

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Wed, 16 Sep 2009 14:35:00 -0700 Five essential things to know about evolution - Ars Technica http://awmitchell.posterous.com/five-essential-things-to-know-about-evolution-0 http://awmitchell.posterous.com/five-essential-things-to-know-about-evolution-0

A really inefficient solution can be a lot better than the alternative

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Evolution solves problems in parallel

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Evolution doesn't happen overnight

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A million years is a lot longer than we think it is

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We wouldn't recognize a key transition while it was happening

A nice summary of some important points.

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Mon, 14 Sep 2009 00:51:09 -0700 Calculating why we see classical behavior in a quantum world - Ars Technica http://awmitchell.posterous.com/calculating-why-we-see-classical-behavior-in http://awmitchell.posterous.com/calculating-why-we-see-classical-behavior-in
One of the remaining mysteries of quantum mechanics is the question of how we transition between the probabilistic world of quantum mechanics and the everyday world of classical objects. From a strict reductionist point of view, everything is quantum, and, yes, you could build a dog if you had the right mixture of quarks and electrons. Although this statement is technically true, it highlights an enormous gap between what we observe reality to be—continuous and largely deterministic—and its foundation, the weird mixture of continuity, descreteness, deterministic evolution, and probabilistic behavior that define the quantum world.

This is an intersting take on what has been an awkward problem.

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Thu, 10 Sep 2009 14:31:08 -0700 NASA - Hubble ERO Images http://awmitchell.posterous.com/nasa-hubble-ero-images http://awmitchell.posterous.com/nasa-hubble-ero-images
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Amazing images from the refurbished Hubble.

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Fri, 28 Aug 2009 21:00:27 -0700 Is quantum mechanics messing with your memory? http://awmitchell.posterous.com/is-quantum-mechanics-messing-with-your-memory http://awmitchell.posterous.com/is-quantum-mechanics-messing-with-your-memory
For all we know we may live in a world in which windows un-break and cold cups of coffee spontaneously heat up, we just don't remember. The explanation is quantum entanglement

An interesting read but probably not true. It does seem a bit forced and, it seems to me, events are not independent so the world would be quite muddled and incomprehensible if this explaintation was true.

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Wed, 26 Aug 2009 03:38:06 -0700 Space probes fly in tandem to search for lunar water - New Scientist http://awmitchell.posterous.com/space-probes-fly-in-tandem-to-search-for-luna http://awmitchell.posterous.com/space-probes-fly-in-tandem-to-search-for-luna

A delicate joint manoeuvre between US and Indian space probes orbiting the moon could turn up evidence for valuable lunar water.

Some scientists suspect water ice – which would be a precious resource for future explorers – may be trapped in permanently shadowed craters at the moon's poles.

Water ice can be distinguished from other materials by the way its radar echoes vary according to the position of the listener. In 1994, the US Clementine spacecraft bounced radar signals off the moon and found hints of the water-ice signature.

It's clear that robotic explorers enable us to do a lot more useful science much more cheaply than human explorers. It's a shame that these robotic explorers are on a mission supporting manned return to moon. What a waste.

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Tue, 25 Aug 2009 14:27:52 -0700 Video: Imagining the Tenth Dimension http://awmitchell.posterous.com/video-imagining-the-tenth-dimension http://awmitchell.posterous.com/video-imagining-the-tenth-dimension

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Tue, 25 Aug 2009 03:35:00 -0700 Our theories may be wrong?!? That IS Good News. http://awmitchell.posterous.com/mystery-of-the-missing-mini-galaxies-space-24 http://awmitchell.posterous.com/mystery-of-the-missing-mini-galaxies-space-24
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Fantastic item from http://www.newscientist.com/this evening. Mystery of the missing mini-galaxies explores an issue with the number of mini-galaxies orbiting our Milky Way galaxy.

As far as we can tell, barely 25 straggly satellites loiter forlornly around the outskirts of the Milky Way. “We see only about 1 per cent of the predicted number of satellite galaxies,” says Pavel Kroupa of the University of Bonn in Germany. “It is the cleanest case in which we can see there is something badly wrong with our standard picture of the origin of galaxies.”

And another issue had been reported earlier where

… most of those galaxies orbit the Milky Way in an unexpected manner and that, taken together, their results are at odds with mainstream cosmology. There is “only one way” to explain the results, says Kroupa: “Gravity has to be stronger than predicted by Newton.”

This latest data is a problem for ‘cold dark matter’ theories which predicted many times more satellite galaxies than have been found. The data supports modified gravity theories.

It’s great for science when evidence mounts that current established theories, such as Newtonian Gravity, need modification. Science is a process that re-works theories to fit all available data. Evidence from nature is the only supreme truth. No theory about how things work is ever accepted as 100% certain and it’s good to be sceptical of current theories no matter how well they may fit available data. When science runs into an uncomfortable truth, it is scientific theories that bend. Science does not bend the evidence to fit the orthodoxy.

Readers may care to consider for themselves how this process differs from theological practice.

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Mon, 24 Aug 2009 14:06:02 -0700 Biological desalination? Bug power makes salt water sweet http://awmitchell.posterous.com/biological-desalination-bug-power-makes-salt http://awmitchell.posterous.com/biological-desalination-bug-power-makes-salt Picture (Device Independent Bitmap)

Ole0

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