格致

The Devil is in the Generalities

• Geeking with Greg: Finding the location of interests and objects from search logs
  • “The most dramatic example… in the paper was estimating the location of a hurricane over time by the queries for the name of the hurricane.”
• Info/Law: Payless and the Terrible, Horrible, No Good, Very Bad Day
  • Adidas apparently owns the trademark on striped shoes, at least according to one judge. (And to the tune of $305 million.)

Click here for all of my del.icio.us bookmarks.

Alas, I have treated the Placebo effect too uncritically in my health econ class.  I'll do better next year.  From Wikipedia:

The original 1955 article of Beecher "The Powerful Placebo" claimed a 35% placebo effect in 15 studies. The original article was in 1997 re-analysed and "no evidence was found of any placebo effect in any of the studies" used by Beecher. ... The claimed "effects" were produced by spontaneous improvement, fluctuation of symptoms, regression to the mean, additional treatment, conditional switching of placebo treatment, scaling bias, irrelevant response variables, answers of politeness, experimental subordination, conditioned answers, neurotic or psychotic misjudgment, psychosomatic phenomena, misquotation, etc. ...

Hróbjartsson and Gøtzsche published a study in 2001 and a follow-up study in 2004 questioning the nature of the placebo effect. ... They performed two meta-analyses involving 156 clinical trials in which an experimental drug or treatment protocol was compared to a placebo group and an untreated group, and ... found that in studies with a binary outcome, meaning patients were classified as improved or not improved, the placebo group had no statistically significant improvement over the no-treatment group. Similarly, there was no significant placebo effect in studies in which objective outcomes (such as blood pressure) were measured by an independent observer. The placebo effect could only be documented in studies in which the outcomes (improvement or failure to improve) were reported by the subjects themselves.

HT to Brandon Reinhart.

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Previously in series:  Spooky Action at a Distance
Followup to:  Decoherence is Simple, Falsifiable and Testable

Back when people didn't know about macroscopic decoherence aka many-worlds - before it occurred to anyone that the laws deduced with such precision for microscopic physics, might apply universally at all levels - what did people think was going on?

The initial reasoning seems to have gone something like:

"When my calculations showed an amplitude of -1/3i for this photon to get absorbed, my experimental statistics showed that the photon was absorbed around 107 times out of 1000, which is a good fit to 1/9, the square of the modulus."

to

"The amplitude is the probability (by way of the squared modulus)."

to

"Once you measure something and know it didn't happen, its probability goes to zero."

Read literally, this implies that knowledge itself - or even conscious awareness - causes the collapse.  Which was in fact the form of the theory put forth by Werner Heisenberg!

But people became increasingly nervous about the notion of importing dualistic language into fundamental physics - as well they should have been!  And so the original reasoning was replaced by the notion of an objective "collapse" that destroyed all parts of the wavefunction except one, and was triggered sometime before superposition grew to human-sized levels.

Now, once you're supposing that parts of the wavefunction can just vanish, you might think to ask:

"Is there only one survivor?  Maybe there are many surviving worlds, but they survive with a frequency determined by their integrated squared modulus, and so the typical surviving world has experimental statistics that match the Born rule."

Yet collapse theories considered in modern academia, only postulate one surviving world.  Why?

Collapse theories were devised in a time when it simply didn't occur to any physicists that more than one world could exist!  People took for granted that measurements had single outcomes - it was an assumption so deep it was invisible, because it was what they saw happening.  Collapse theories were devised to explain why measurements had single outcomes, rather than (in full generality) why experimental statistics matched the Born rule.

For similar reasons, the "collapse postulates" considered academically, suppose that collapse occurs before any human beings get superposed.  But experiments are steadily ruling out the possibility of "collapse" in increasingly large entangled systems.  Apparently an experiment is underway to demonstrate quantum superposition at 50-micrometer scales, which is bigger than most neurons and getting up toward the diameter of some human hairs!

So why doesn't someone try jumping ahead of the game, and ask:

"Say, we keep having to postulate the collapse occurs steadily later and later.  What if collapse occurs only once superposition reaches planetary scales and substantial divergence occurs - say, Earth's wavefunction collapses around once a minute?  Then, while the surviving Earths at any given time would remember a long history of quantum experiments that matched the Born statistics, a supermajority of those Earths would begin obtaining non-Born results from quantum experiments and then abruptly cease to exist a minute later."

Why don't collapse theories like that one have a huge academic following, among the many people who apparently think it's okay for parts of the wavefunction to just vanish?  Especially given that experiments are proving superposition in steadily larger systems?

A cynic might suggest that the reason for collapse's continued support, isn't the physical plausibility of having large parts of the wavefunction suddenly vanish, or the hope of somehow explaining the Born statistics.  The point is to keep the intuitive appeal of "I don't remember the measurement having more than one result, therefore only one thing happened; I don't remember splitting, so there must be only one of me."  You don't remember dying, so superposed humans must never collapse.  A theory that dared to stomp on intuition would be missing the whole point.  You might as well just move on to decoherence.

So a cynic might suggest.

But surely it is too early to be attacking the motives of collapse supporters.  That is mere argument ad hominem.  What about the actual physical plausibility of collapse theories?

Well, first:  Does any collapse theory have any experimental support?  No.

With that out of the way...

If collapse actually worked the way its adherents say it does, it would be:

1. The only non-linear evolution in all of quantum mechanics.
2. The only non-unitary evolution in all of quantum mechanics.
3. The only non-differentiable (in fact, discontinuous) phenomenon in all of quantum mechanics.
4. The only phenomenon in all of quantum mechanics that is non-local in the configuration space.
5. The only phenomenon in all of physics that violates CPT symmetry.
6. The only phenomenon in all of physics that violates Liouville's Theorem (has a many-to-one mapping from initial conditions to outcomes).
7. The only phenomenon in all of physics that is acausal / non-deterministic / inherently random.
8. The only phenomenon in all of physics that is non-local in spacetime and propagates an influence faster than light.

WHAT DOES THE GOD-DAMNED COLLAPSE POSTULATE HAVE TO DO FOR PHYSICISTS TO REJECT IT?  KILL A GOD-DAMNED PUPPY?

刚买了一个闪光灯，比以前用过的复杂得多，试照了小黑猫：

Not having purchased a full subscription to New England Journal of Medicine I haven’t access to the article “Amebiasis from the ‘Miraculous Water of Tlacote” [which you mentioned]. Nonetheless I’ve taken tlacote tablets for three years and have suffered no ill effects. In fact I’ve found it most helpful. Millions of people have availed themselves of the water, either in liquid or homeopathic form. Where is the evidence of a health issue precipitated by ingesting this water? I submit the case of Amebiasis cited above was from another water source. Thus I find the Improbable Research article [on the web site, written in 2001] fits well under the heading of “hot air.” A New Light is entering the World. Find out more at:http://www.share-international.org.

David E. Mynott II
Boston, MA

(That’s an excerpt from the article “Air Vents,” published in AIR 11:1)

The mothership, aka Seed magazine, has a crib sheet for quantum computing. Its not half bad, considering how bad things like this can go. And of course this is probably due in part to the fact that they list the Optimizer as a consultant. But the real question is whether that little shade of black outside of NP is an illustrators trick or the result of a complexity theorist being the person they asked to vet the cheat sheet?

昨天女儿在学校做了一份剪纸作业，我看还挺有意思，用扫描仪扫了一下。

今年4月1日，新修订的《节约能源法》开始实施。为了更好地探讨如何促进节能减排的报道，促进积极应对气候变化的挑战，气候变化报道俱乐部将于5月13日下午在清华大学建筑节能楼召开一次专家与媒体之间的座谈会“《节约能源法》的制定与实施——建筑节能为例”，希望诸位关心气候变化报道的媒体工作者与专家就这个问题共同展开探讨。

下面是活动的初步议程：    
主题：《节约能源法》的制定与实施——建筑节能为例
时间：5月13日下午两点
地点：清华大学节能示范楼/清华大学建筑节能研究中心（东门建筑学院东侧）

主讲嘉宾（每人20分钟左右）：
江  亿（清华大学建筑系/中国工程院院士）
姜克隽（发改委能源所）
李命志（全国人大财政经济委员会经济室）
邓海峰（清华大学环境资源能源法研究中心）
讨论及自由提问（一小时）

本次活动得到了伯尔基金会的支持。名额有限，报名参会请联系刘振华（zhenhua9756 @ sina.com）。

信息来源：http://www.climatereporting.cn