Wednesday, September 29, 2010

No hawks in church please

I'm reading The Wars of the Roses by Alison WeirKing Henry VI of England was pious, even to the extent that he would not allow his courtiers to bring their hawks into church.  Apparently in the middle ages it was customary to bring your hawks and dogs to church and there were even cases when the right to do so was an express stipulation.

Strange radio pulses

In 2007 there was a report in Science of an intense radio burst which overloaded the detector at the Parkes radiotelescope in Australia. It was originally thought that the burst must be of extragalactic origin and of incredible power.  But in the meantime 16 additional similar pulses have been identified at Parkes - however they clearly originate on or near the Earth.  But the exact source is still unknown:  Radio Bursts with Extragalactic Spectral Characteristics Show Terrestrial Origins  .  The authors of that report whimsically refer to these odd bursts as "Perytons" after a winged deer which casts the shadow of a man in Borges'  Book of Imaginery Beings.
Parkes radio telescope

Tuesday, September 28, 2010

Post 666

The Number of the Beast is 666 - William Blake
﻿﻿ ﻿ ﻿﻿﻿ This is my 666th blog post.  In honor of this rather dubious milestone, here's a selection of 42 of the over one hundred articles I've edited on another website, Wikipedia.

Aerobic anoxygenic phototrophic bacteria:  very abundant marine plankton.

Big Bang nucleosynthesis:  there is an unexplained discrepancy for the element Lithium.

Linda B. Buck:  a Nobel prize winner in biology - recently retracted publications.

Lois McMaster Bujold:  award winning scifi and fantasy author.

Cartesian Coordinates:  French philosopher Oreseme anticipated Descartes by centuries.

Cassiopeia A:  a supernova remnant and a very strong radio source.

Clovis point:  beautiful spear points from ancient America.

Coherent perfect absorber:  a time-reversed laser.

 Dwarf galaxy problem:  there aren't as many as expected.

Geminga:  an unusual neutron star which generated the Local Bubble.

J. Richard Gott: Princeton professor of astrophysics with a Doomsday Theory.

GSI anomaly:  unexplained oscillations detected at a German laboratory.

Guzheng:  a classical Chinese musical instrument.

Haptophyte: tiny uncultured pico-prymnesiophytes are ecologically important.

Helical Dirac fermion:  behaves like a massless relativistic particle.

Helitron:  DNA which replicates by a rolling-circle mechanism.

 Inner Core:  the central core of the earth has an East-West asymmetry.

Richard J. Lipton:  computer scientist, Gödel's Lost Letter and P=NP is his blog.

Local Void:  a vast empty region of space near our Milky Way galaxy.

Mira B: the companion of the variable star Mira is now believed to be a white dwarf.

National Spatial Reference System: is a coordinate system managed by the US.

Pre-solar nebula:  a supernova shock wave may have triggered the formation of the Sun.

Puerto Plata:  is a resort town on the north coast of the Dominican Republic.

Ptychography:  allows X-ray microscopes without using lenses.

Quantum Gravity:  this theory has a Problem with Time.

The Rose of Versailles:  is a Japanese manga set during the French Revolution.

RX J0852.0-4622:  a nearby supernova which should have been visible around 1250.

SCP 06F6: an extremely luminous supernova. 

Second harmonic imaging microscopy:  useful in imaging in living tissues.

Segue 1:  a dwarf galaxy dominated by Dark Matter.

Three Tales:  the tale A Simple Heart by Flaubert inspired the novel Flaubert's Parrot.

Time dilation :  A surprising consequence of relativity.

Topological insulator:  an exotic material that has insulating and conducting regions.

Torquetum:  a medieval astronomical instrument.

Transit of Venus: Venus will cross the face of the Sun again in 2012.

Type IIn supernovae:  extremely energetic supernovae.

Type IIb supernovae:  a star with a mostly helium core explodes.

Venus: the planet was completely resurfaced 300-600 million years ago.

Water window: water is transparent to part of the X-ray spectrum.

Xenocarida:  the "strange shrimp" are a group of recently discovered Crustacea.

Shing-Tung Yau:  distinguished mathematician, Poincaire conjecture controversy.

 Zero Morphism: is a concept in the mathematical subject Category Theory.


Oxygen increase in the Devonian Period

There's new evidence of a substantial increase in ocean oxygen content during the Devonian period about 400 million years ago.  That was around the time that vascular plants arose, so perhaps that's what caused the increase.  At the same time more complicated animals such as predatory fish evolved  - so perhaps the higher level of oxygen is what made that possible.   See Plants set stage for evolutionary drama in Nature.

Monday, September 27, 2010

Shakespearean Titles

Many literary works derived their titles from passages in Shakespeare, e.g. Brave New World, The Sound and the Fury.
Another one of my favorites is the poem/novel Pale Fire by Vladimir Nabokov.

The moon's an arrant thief,
And her pale fire she snatches from the sun.
       Timon of Athens

Once I got caught in a strange web created by Nabokov and another author which involved the following lines from Pale Fire:

Space is a swarming in the eyes,
and Time a singing in the ears

 I was reading the Nabokov novel Ada.  In Ada Nabokov mentioned the lines above as quoted by "the invented philosopher Martin Gardiner".  I thought I was hallucinating, since coincidentally I was also in the middle of reading a popular science book The Ambidextrous Universe with a nearly identical author -  Martin Gardner.  Fortunately it happened to be the second edition of the Ambidextrous Universe, which, when I read further, provided the explanation.  Nabokov's misspelling of Gardner's name was probably deliberate!

By the way, it probably wouldn't be too surprising if even a humble blog might have had the nerve to derive its title from a well-known passage in Shakespeare.

Two Plays by Tom Stoppard

I just reread The Real Inspector Hound and After Magritte, two plays by Tom StoppardThe Real Inspector Hound, a parody of the "murder at the stately English country home" genre, is much the better.  But my favorite exchange was in After Magritte:

THELMA:  ... All I can say is I'll be glad when it's all over and things are back to normal.  It's making you short-tempered and argumentative.  You contradict everything I say --
HARRIS: (heatedlyThat I deny --

What if, instead of contradicting her, Harris had agreed with Thelma and said "You're right"? 

Stoppard has worked on film scripts as well as theater.  The dystopian film Brazil, directed by Terry Gilliam, is one of my favorites.  I didn't realize that he also contributed much of the dialog for Indiana Jones and the Last Crusade, a Steven Spielberg film that I also enjoyed.

This (substantive) modification of Stoppard's dialog has bothered me:

ALICE:  You contradict everything I say.
BOB:  You're right.

I considered whether this might be some variant of the Liar Paradox similar to:

The next sentence is false.
The previous sentence is true.

That really is a logical paradox:  try to make the first sentence true - it doesn't work;  try to make the first sentence false - it doesn't work either.

But there's really no logical problem with Alice and Bob.  Alice's statement is false and so is Bob's.  Bob's response falsifies Alice's previous statement.  Bob proves Alice wrong by agreeing with her.  However since Bob proved Alice wrong, in a certain sense he actually did contradict her.   Which would seem to make Alice's statement true (or at least it could be true - assuming all of Bob's other statements also contradicted her).  But didn't I just say it was false?  Still it isn't really a paradox in pure logic.  Is it?

While we're at it, let's take a look at this stripped-down version of Stoppard's original Thelma and Harris exchange:

THELMA: You contradict everything I say.
HARRIS: That I deny.

Thelma's statement could be true (at least when Harris contradicts her in all other cases - let's go ahead assume that).  The Harris statement denies what Thelma just said, that denial counts as a contradiction (I suppose) and so the Harris statement is consistent with the meaning of Thelma's assertion.  Hence, the Harris statement supports Thelma's assertion.  Then given that we're assuming Harris otherwise contradicts Thelma, Thelma's statement must be true.  On the other hand, Thelma asserts that Harris contradicts everything she says and Harris' subsequent statement supports that.  If Harris' statement supports Thelma's statement, it can hardly be contradicting her.  So Thelma's statment must be false.  But didn't I just say Thelma's statement must be true?  Oops. 

What do you think?  But please, don't contradict everything I say.

--- Tweedledee in Through the Looking Glass by Lewis Carroll.

Time Will End

The preprint Eternal inflation predicts that time will end argues that cosmological theories which include "eternal inflation" will lead to the end of time - their estimate is 5 billion years for our galaxy.  It may seem like you still have plenty of time, but it's never too soon to panic.

Saturday, September 25, 2010

Television Novels





Friday, September 24, 2010

Aristotle's wheel paradox

Embarrassingly I'm still slowly reading Galileo at Work: His Scientific Biography by Stillman DrakeAristotle's wheel paradox came up several times in the book so I finally looked it up at Wikipedia.
When the inner and outer attached wheels make a complete revolution, they trace out lines of equal length, yet their circumferences are different.
How can that be?

Thursday, September 23, 2010

SCP 06F6

SCP 06F6 is a very unusual object discovered in 2006 by the Hubble Space Telescope.  Its spectrum and light curve are unlike any other known. Initial observations weren't able to identify any of the typical spectral lines. The Palomar Transient Factory was able to determine its redshift (z = 1.189) and that its luminosity is one of the highest currently known:  Mysterious transients unmasked as the bright blue death throes of massive stars.

Tuesday, September 21, 2010

AntiNeutrino surprise at MINOS

One of the fundamental principles of particle physics is that particles and their anti-particles should have the same mass.  So it was a big surprise when Fermilab MINOS collaboration found that the muon neutrino and muon antineutrino appear to have different masses.  Neutrino experiments are extraordinarily difficult because neutrinos are so hard to detect.  This result is still very preliminary.  But if it does hold up, the impact on theoretical physics will be earthshaking.
See Neutrino surprise emerges from MINOS at PhysicsWorld .

Monday, September 20, 2010

The Sky in Boston tonight

was spectacular. Venus just after sunset in the West and a nearly full moon and a gigantic Jupiter in East, one of its closest approaches to Earth. All four of the major satellites of Jupiter were lined up and nearby was Uranus - actually the first time I believe I've ever seen it, with binoculars.
Unfortunately I couldn't see the following sight (Carina Nebula) with my binoculars, it is in the Southern Hemisphere, but the Hubble Space Telescope did.

Dimensionality of the Universe

One of the most mysterious facts about our universe is that, for most purposes, it can be modelled as four-dimensional: with one dimension for time and three dimensions for space. Why four, why not three, why not 42? There have long been proposals that add more dimensions, especially extra spatial dimensions, which are curled up so tightly that we don't normally perceive them.
The following preprint proposes something different. At very small scales (subatomic) there are effectively fewer than three spatial dimensions while at very large scales (cosmological) there are effectively more than three spatial dimensions!
Vanishing Dimensions and Planar Events at the LHC
We propose that the effective dimensionality of the space we live in depends on the length scale we are probing. As the length scale increases, new dimensions open up. At short scales the space is lower dimensional; at the intermediate scales the space is three-dimensional; and at large scales, the space is effectively higher dimensional. This setup allows for some fundamental problems in cosmology, gravity, and particle physics to be attacked from a new perspective. The proposed framework, among the other things, offers a new approach to the cosmological constant problem and results in striking collider phenomenology and may explain elongated jets observed in cosmic-ray data.

Saturday, September 18, 2010

Event honoring Feynman.

TEDxCaltech, an exciting one-day event to honor Richard Feynman.

Codons matter

DNA codes for amino acids with triplets of bases (codons). There are four different bases and hence 64 different triplets. There are typically twenty different amino acids (plus start and stop signals) which need to be coded, so there is some redundancy - a single amino acid can have multiple codons which are all translated the same way. However, there is now evidence that the actual codon may make a difference. New Roles for Codon Usage in Science reports that two very similar but distinct proteins are modified differently, depending on the original codon.

Tuesday, September 14, 2010

Bowerbirds use an optical illusion to trick their mates

Bowerbirds trick mates with optical illusions at Nature News. Male bowerbirds construct their bowers to create an optical illusion called forced perspective which makes them appear bigger than they really are.

The Problem of Time

The Problem of Time in Quantum Gravity
The problem of time in quantum gravity occurs because `time' is taken to have a different meaning in each of general relativity and ordinary quantum theory. This incompatibility creates serious problems with trying to replace these two branches of physics with a single framework in regimes in which neither quantum theory nor general relativity can be neglected, such as in black holes or in the very early universe.

Monday, September 13, 2010

The heliospheric current sheet

"The Sun with the heliosheet is like a bashful ballerina who is repeatedly trying to push her excessively high flaring skirt downward".

Wednesday, September 08, 2010


A first draft of a non-technical article on universality by Fields medallist Terence Tao. Talks about universality: when important attributes of a large-scale system can be independent of how the system works at smaller scales.

Tuesday, September 07, 2010

Solar Neutrinos

The preprint Solar neutrinos, helioseismology and the solar internal dynamics begins with an interesting history of the "solar neutrino problem".

The Mafia Game

The mafia game (or werewolf or assassin game) is a party game in which the organiser divides the players into two groups: the citizens and the mafia. The mafia are told who the other mafia are, but the citizens don't know. The game alternates between the "day" when all the players decide who to "lynch" and the "night" when just the mafia decide who to eliminate. The game ends when either all the citizens or all the mafia are eliminated.
The preprint A mathematical model of the Mafia game provides an analysis of strategy.

Monday, September 06, 2010

Testing the Universality of Free Fall

There's an interesting debate in Nature about atom interferometry tests of gravitational redshifts and what they imply about the university of free fall and the Einstein equivalence principle. See the preprint Atom gravimeters and gravitational redshift and the reply. See also the preprint Gravitational Redshift, Equivalence Principle, and Matter Waves. One of the authors in this controversy is Nobel prize winner and Department of Energy secretary Steven Chu.

Saturday, September 04, 2010

The Copernican Principle

The Copernican Principle posits that the Earth is not in any particularly special location in the universe. Prior to Copernicus, the Earth had been placed in the center of the universe and historically there was much resistance to moving it - early in his career even Galileo had a fanciful rationale for putting the earth at the center.
The Standard Model of Cosmology pretty much enshrines the Copernican Principle. It has had some success explaining phenomenon like the extragalactic redshifts, microwave background radiation and the abundances of light elements.
However there are some difficulties with this model, especially the observed acceleration of the redshifts (Dark Energy) and the abundance of lithium 7.
The preprint Do primordial Lithium abundances imply there's no Dark Energy? explains these observations by heretically suggesting that the Earth might be in a rather special place after all: near the center of a gigantic void. See also The Cosmic Microwave Background in an Inhomogeneous Universe - why void models of dark energy are only weakly constrained by the CMB by the same authors.

Friday, September 03, 2010

A Light Sucker

Laser science: Suckers for light in Nature.

A Coherent perfect absorber is:
An optical device has been designed that performs a function exactly opposite to that of a laser. It perfectly absorbs incoming coherent radiation and turns it into thermal or electrical energy.

Backward lasing yields a perfect absorber
Just as a laser can emit coherent light from an amplifying medium, an absorbing medium can perfectly capture incoming radiation under the right conditions

CPA-based interferometers could thus have potential applications in the realization of transducers, modulators, or optical switches, for example, in on-chip integrated optical circuits based on Si waveguide/resonator technology.

The Sun's Elements

An Unsettled Debate About the Chemistry of the Sun in Science.
There's a debate about how much carbon, nitrogen, oxygen and neon the sun contains. NASA

Thursday, September 02, 2010

Probability Puzzles

There's an intersting discussion of some confusing Probability Puzzles on John Baez's new blog.


The "born on a Tuesday" information can't possibly make a difference, can it? So the answer should be same same as:

“I have two children. One is a boy. What is the probability I have two boys?”

Shoudn't it?

There's a thorough analysis at Some Thoughts on Tuesday's Child by Greg Egan.