Bird Fact Friday – Weekly Warbler: Worming-eating

Welcome back to the warblers!

From page 460-461 in The Warbler Guide:

The worm-eating warbler can be identified by its mustard-colored head with four bold black stripes. It has long, pale, and slightly curved bill, and plain, dusky-olive back and wings. The male and female worm-eating warblers look the same in all seasons. The worm-eating warbler is deliberate and acrobatic in its explorations of the understory. It specializes in picking insects from hanging dead leaves.

The Warbler Guide
Tom Stephenson & Scott Whittle
Drawings by Catherine Hamilton
Warbler Guide App
Species Account Example: American Redstart Male

Warblers are amwarblerong the most challenging birds to identify. They exhibit an array of seasonal plumages and have distinctive yet oft-confused calls and songs. The Warbler Guide enables you to quickly identify any of the 56 species of warblers in the United States and Canada. This groundbreaking guide features more than 1,000 stunning color photos, extensive species accounts with multiple viewing angles, and an entirely new system of vocalization analysis that helps you distinguish songs and calls.

The Warbler Guide revolutionizes birdwatching, making warbler identification easier than ever before. For more information, please see the author videos on the Princeton University Press website.

Cipher challenge #2 from Joshua Holden: Subliminal channels

The Mathematics of Secrets by Joshua Holden takes readers on a tour of the mathematics behind cryptography. Most books about cryptography are organized historically, or around how codes and ciphers have been used in government and military intelligence or bank transactions. Holden instead focuses on how mathematical principles underpin the ways that different codes and ciphers operate. Discussing the majority of ancient and modern ciphers currently known, The Mathematics of Secrets sheds light on both code making and code breaking. Over the next few weeks, we’ll be running a series of cipher challenges from Joshua Holden. The first was on Merkle’s puzzles. Today’s focuses on subliminal channels:

As I explain in Section 1.6 of The Mathematics of Secrets, in 1929 Lester Hill invented the first general method for encrypting messages using a set of multiple equations in multiple unknowns.  A less general version, however, had already appeared in 1926, submitted by an 18-year-old to a cryptography column in a detective magazine.  This was Jack Levine, who would later become a prolific researcher in several areas of mathematics, including cryptography.

Levine’s system was billed as a way of encrypting two different messages at the same time.  Maybe one of them was the real message and the other was a dummy message–if the message was intercepted, the interceptor could be thrown off the scent by showing them the dummy message.  This sort of system is now known as a subliminal channel.

The system starts with numbering the letters of the alphabet in two different ways:

   a  b  c  d  e  f  g  h  i  j  k  l  m
  27 28 29 30 31 32 33 34 35 36 37 38 39
   1  2  3  4  5  6  7  8  9 10 11 12 13
  
   n  o  p  q  r  s  t  u  v  w  x  y  z
  40 41 42 43 44 45 46 47 48 49 50 51 52
  14 15 16 17 18 19 20 21 22 23 24 25 26

Suppose the first plaintext, or unencrypted message, is “tuesday” and the second plaintext is “tonight.”  We use the first set of numbers for the first plaintext:

   t  u  e  s  d  a  y
  46 47 31 45 30 27 51

and the second set for the second plaintext:

   t  o  n  i  g  h  t
  20 15 14  9  7  8 20

The encrypted message, or ciphertext, is made up of pairs of numbers.  The first number in each pair is half the sum of the two message numbers, and the second number is half the difference:

    t       u        e       s       d       a        y
   46      47       31      45      30      27       51
  
    t       o        n       i       g       h        t
   20      15       14       9       7       8       20
  
33,13    31,16  22½,8½   27,18 18½,11½  17½,9½  35½,15½

To decrypt the first message, just take the sum of the two numbers in the pair, and to decrypt the second message just take the difference.  This works because if P1 is the first plaintext number and P2 is the second, then the first ciphertext number is

and the second is

Then the plaintext can be recovered from the ciphertext using

and

This system is not as secure as Hill’s because it gives away too much information.  For starters, the existence and nature of the fractions is a clue to the encryption process.  (The editor of the cryptography column suggested doubling the numbers to avoid the fractions, but then the pattern of odd and even numbers would still give information away.)  Also, the first number in each pair is always between 14 and 39 and is always larger than the second number, which is always between ½ and 25 ½.  This suggests that subtraction might be relevant, and the fact that there are twice as many numbers as letters might make a codebreaker suspect the existence of a second message and a second process.  Hill’s system solves some of these issues, but the problem of information leakage continues to be relevant with modern-day ciphers.

With those hints in mind, can you break the cipher used in the following message?

11 3/5, 15 4/5   10 4/5,  9 2/5   17,     11        14 1/5, 16 3/5
 9 4/5,  7 2/5   12 3/5,  7 4/5    9 2/5, 12  1/5   13 1/5, 13 3/5
18,     11       12 2/5, 14 1/5    8 4/5, 10  2/5   12 1/5,  6 3/5
15 4/5, 12 2/5   13 3/5, 13 4/5   12,     16        11 2/5,  8 1/5
 9 1/5, 16 3/5   14,     17       16 3/5, 12  4/5    9 4/5, 14 2/5
12 1/5,  6 3/5   11 3/5, 15 4/5   10,     11        11 4/5,  6 2/5
10 2/5, 14 1/5   17 2/5, 12 1/5   14 3/5,  9  4/5

Once you have the two plaintexts, can you deduce the process used to encrypt them?

 

Answer to Cipher Challenge #1: Merkle’s Puzzles

The hole in the version of Merkle’s puzzles is that the shift we used for encrypting is vulnerable to a known-plaintext attack. That means that if Eve knows the ciphertext and part of the plaintext, she can get the rest of the plaintext. In Cipher Challenge #1, she knew that the word “ten” is part of the plaintext. So she shifts it until she finds a ciphertext that matches one of the puzzles:

ten
UFO
VGP

“Aha!” says Eve. “The first puzzle starts with VGP, so it must decrypt to ten!” Then she decrypts the rest of the puzzle:

VGPVY QUGXG PVYGP VAQPG UKZVG GPUGX GPVGG PBTPU XSNHT JZFEB
whqwz rvhyh qwzhq wbrqh vlawh hqvhy hqwhh qcuqv ytoiu kagfc
xirxa swizi rxair xcsri wmbxi irwiz irxii rdvrw zupjv lbhgd
yjsyb txjaj sybjs ydtsj xncyj jsxja jsyjj sewsx avqkw mcihe
                             ⋮
qbkqt lpbsb kqtbk qvlkb pfuqb bkpbs bkqbb kwokp snico euazw
rclru mqctc lrucl rwmlc qgvrc clqct clrcc lxplq tojdp fvbax
sdmsv nrdud msvdm sxnmd rhwsd dmrdu dmsdd myqmr upkeq gwcby
tentw oseve ntwen tyone sixte ensev entee nzrns vqlfr hxdcz

So the secret key is 2, 7, 21, 16.

The hole can be fixed by using a cipher that is less vulnerable to known-plaintext attacks. Sections 4.4 and 4.5 of The Mathematics of Secrets give examples of ciphers that would be more secure.

Bird Fact Friday—Weekly Warbler: Black-and-White

Welcome back to the warblers!

As we approach the launch of our long-awaited Warbler Guide App for Android, we’re highlighting some fun facts about the warblers with a new Weekly Warbler feature. Kicking it off today is the black and white warbler.

From page 160-161 in The Warbler Guide:

The black-and-white warbler is distinctive in many features. Its black-and-white crown stripes are diagnostic. It has long and slightly curved bill, very broad white supercilium, and contrasty white wing bars joining wide white tertial edgings. Its black-and-white pattern is striking even in flight. It likes to creep on trunks and limbs, and more interestingly, to creep downward. It is the longest-lived warbler on record, at eleven years.

 

The Warbler Guide
Tom Stephenson & Scott Whittle
Drawings by Catherine Hamilton
Warbler Guide App
Species Account Example: American Redstart Male

 

Warblers are amwarblerong the most challenging birds to identify. They exhibit an array of seasonal plumages and have distinctive yet oft-confused calls and songs. The Warbler Guide enables you to quickly identify any of the 56 species of warblers in the United States and Canada. This groundbreaking guide features more than 1,000 stunning color photos, extensive species accounts with multiple viewing angles, and an entirely new system of vocalization analysis that helps you distinguish songs and calls.

The Warbler Guide revolutionizes birdwatching, making warbler identification easier than ever before. For more information, please see the author videos on the Princeton University Press website.

 

Cipher challenge #1 from Joshua Holden: Merkle’s Puzzles

The Mathematics of Secrets by Joshua Holden takes readers on a tour of the mathematics behind cryptography. Most books about cryptography are organized historically, or around how codes and ciphers have been used in government and military intelligence or bank transactions. Holden instead focuses on how mathematical principles underpin the ways that different codes and ciphers operate. Discussing the majority of ancient and modern ciphers currently known, The Mathematics of Secrets sheds light on both code making and code breaking. Over the next few weeks, we’ll be running a series of cipher challenges from Joshua Holden. Presenting the first, on Merkle’s puzzles. 

For over two thousand years, everyone assumed that before Alice and Bob start sending secret messages, they’d need to get together somewhere where an eavesdropper couldn’t overhear them in order to agree on the secret key they would use. In the fall of 1974, Ralph Merkle was an undergraduate at the University of California, Berkeley, and taking a class in computer security. He began wondering if there was a way around the assumption that everyone had always made. Was it possible for Alice to send Bob a message without having them agree on a key beforehand? Systems that do this are now called public-key cryptography, and they are a key ingredient in Internet commerce. Maybe Alice and Bob could agree on a key through some process that the eavesdropper couldn’t understand, even if she could overhear it.

Merkle’s idea, which is now commonly known as Merkle’s puzzles, was slow to be accepted and went through several revisions. Here is the version that was finally published. Alice starts by creating a large number of encrypted messages (the puzzles) and sends them to Bob.

The beginning of Merkle’s puzzles.

Merkle suggested that the encryption should be chosen so that breaking each puzzle by brute force is “tedious, but quite possible.” For our very small example, we will just use a cipher which shifts each letter in the message by a specified number of letters. Here are ten puzzles:

VGPVY QUGXG PVYGP VAQPG UKZVG GPUGX GPVGG PBTPU XSNHT JZFEB
GJBAV ARSVI RFRIR AGRRA GJRYI RFRIR AGRRA VTDHC BMABD QMPUP
AFSPO JOFUF FOUFO TFWFO UXFOU ZGJWF TFWFO UFFOI RCXJQ EHHZF
JIZJI ZNDSO RZIOT ADAOZ ZINZQ ZIOZZ IWOPL KDWJH SEXRJ IKAVV
YBJSY DSNSJ YJJSY BJSYD KNAJX JAJSK TZWXJ AJSYJ JSFNY UZAKM
QCTCL RFPCC RUCLR WDMSP RCCLD GDRCC LQCTC LRCCL JLXUW HAYDT
ADLUA FMVBY ALUVU LVULZ LCLUZ LCLUA LLUGE AMPWB PSEQG IKDSV
JXHUU VYLUJ XHUUJ UDDYD UIULU DJUUD AUTRC SGBOD ALQUS ERDWN
RDUDM SDDMS VDMSX RDUDM SDDMM HMDSD DMRHW SDDMR DUDMS DDMAW
BEMTD MBEMV BGBPZ MMMQO PBMMV AMDMV NQDMA MDMVB MMVUR YCEZC

Alice explains to Bob that each puzzle consists of three sets of numbers. The first number is an ID number to identify the puzzle. The second set of numbers is a secret key from a more secure cipher which Alice and Bob could actually use to communicate. The last number is the same for all puzzles and is a check so that Bob can make sure he has solved the puzzle correctly. Finally, the puzzles are padded with random letters so that they are all the same length, and each puzzle is encrypted by shifting a different number of letters.

Bob picks one of the puzzles at random and solves it by a brute force search. He then sends Alice the ID number encrypted in the puzzle.

Bob solves the puzzle.

For example, if he picked the puzzle on the fifth line above, he might try shifting the letters:

YBJSY DSNSJ YJJSY BJSYD KNAJX JAJSK TZWXJ AJSYJ JSFNY UZAKM
zcktz etotk zkktz cktze lobky kbktl uaxyk bktzk ktgoz vabln
adlua fupul allua dluaf mpclz lclum vbyzl clual luhpa wbcmo
bemvb gvqvm bmmvb emvbg nqdma mdmvn wczam dmvbm mviqb xcdnp

qtbkq vkfkb qbbkq tbkqv cfsbp bsbkc lropb sbkqb bkxfq mrsce
ruclr wlglc rcclr uclrw dgtcq ctcld mspqc tclrc clygr nstdf
svdms xmhmd sddms vdmsx ehudr dudme ntqrd udmsd dmzhs otueg
twent ynine teent wenty fives evenf ourse vente enait puvfh

Now he knows the ID number is “twenty” and the secret key is 19, 25, 7, 4. He sends Alice “twenty”.

Alice has a list of the decrypted puzzles, sorted by ID number:

ID secret key check
zero nineteen ten seven twentyfive seventeen
one one six twenty fifteen seventeen
two nine five seventeen twelve seventeen
three five three ten nine seventeen
seventeen twenty seventeen nineteen sixteen seventeen
twenty nineteen twentyfive seven four seventeen
twentyfour ten one one seven seventeen

So she can also look up the secret key and find that it is 19, 25, 7, 4. Now Alice and Bob both know a secret key to a secure cipher, and they can start sending encrypted messages. (For examples of ciphers they might use, see Sections 1.6, 4.4, and 4.5 of The Mathematics of Secrets.)

Alice and Bob both have the secret key.

Can Eve the eavesdropper figure out the secret key? Let’s see what she has overheard. She has the encryptions of all of the puzzles, and the check number. She doesn’t know which puzzle Bob picked, but she does know that the ID number was “twenty”. And she doesn’t have Alice’s list of decrypted puzzles. It looks like she has to solve all of the puzzles before she can figure out which one Bob picked and get the secret key. This of course is possible, but will take her a lot longer than the procedure took Alice or Bob.

Eve can’t keep up.

Merkle’s puzzles were always a proof of concept — even Merkle knew that they wouldn’t work in practice. Alice and Bob’s advantage over Eve just isn’t large enough. Nevertheless, they had a direct impact on the development of public-key systems that are still very much in use on the Internet, such as the ones in Chapters 7 and 8 of The Mathematics of Secrets.

Actually, the version of Merkle’s puzzles that I’ve given here has a hole in it. The shift cipher has a weakness that lets Eve use Bob’s ID number to figure out which puzzle he solved without solving them herself. Can you use it to find the secret key which goes with ID number “ten”?

Dalton Conley & Jason Fletcher on how genomics is transforming the social sciences

GenomeSocial sciences have long been leery of genetics, but in the past decade, a small but intrepid group of economists, political scientists, and sociologists have harnessed the genomics revolution to paint a more complete picture of human social life. The Genome Factor shows how genomics is transforming the social sciences—and how social scientists are integrating both nature and nurture into a unified, comprehensive understanding of human behavior at both the individual and society-wide levels. The book raises pertinent questions: Can and should we target policies based on genotype? What evidence demonstrates how genes and environments work together to produce socioeconomic outcomes? Recently, The Genome Factor‘s authors, Dalton Conley and Jason Fletcher, answered some questions about their work.

What inspired you to write The Genome Factor?

JF: Our book discusses how findings and theories in genetics and biological sciences have shaped social science inquiry—the theories, methodologies, and interpretations of findings used in economics, sociology, political science, and related disciplines —both historically and in the newer era of molecular genetics. We have witnessed, and participated in, a period of rapid change and cross-pollination between the social and biological sciences. Our book draws out some of the major implications of this cross-pollination—we particularly focus on how new findings in genetics has overturned ideas and theories in the social sciences. We also use a critical eye to evaluate what social scientists and the broader public should believe about the overwhelming number of new findings produced in genetics.

What insights did you learn in writing the book?

JF: Genetics, the human genome project in particular, has been quite successful and influential in the past two decades, but has also experienced major setbacks and is still reeling from years of disappointments and a paradigm shift. There has been a major re-evaluation and resetting of expectations the clarity and power of genetic effects. Only 15 years ago, a main model was on the so-called OGOD model—one gene, one disease. While there are a few important examples where this model works, it has mostly failed. This failure has had wide implications on how genetic analysis is conducted as well as a rethinking of previous results; many of which are now thought to false findings. Now, much analysis is conducted using data 10s or 100s of thousands of people because the thinking is that most disease is caused by tens, hundreds, or even thousands of genes that each have a tiny effect. This shift has major implications for social science as well. It means genetic effects are diffuse and subtle, which makes it challenging to combine genetic and social science research. Genetics has also shifted from a science of mechanistic understanding to a large scale data mining enterprises. As social scientists, this approach is in opposition to our norms of producing evidence. This is something we will need to struggle through in the future.

How did you select the topics for the book chapters?

JF: We wanted to tackle big topics across multiple disciplines. We discuss some of the recent history of combining genetics and social science, before the molecular revolution when “genetics” were inferred from family relationships rather than measured directly. We then pivot to provide examples of cutting edge research in economics and sociology that has incorporated genetics to push social science inquiry forward. One example is the use of population genetic changes as a determinant of levels of economic development across the world. We also focus our attention to the near future and discuss how policy decisions may be affected by the inclusion of genetic data into social science and policy analysis. Can and should we target policies based on genotype? What evidence do we have that demonstrates how genes and environments work together to produce socioeconomic outcomes?

What impact do you hope The Genome Factor will have?

JF: We hope that readers see the promise as well as the perils of combining genetic and social science analysis. We provide a lot of examples of ongoing work, but also want to show the reader how we think about the larger issues that will remain as genetics progresses. We seek to show the reader how to look through a social science lens when thinking about genetic discoveries. This is a rapidly advancing field, so the particular examples we discuss will be out of date soon, but we want our broader ideas and lens to have longer staying power. As an example, advances in gene editing (CRISPR) have the potential to fundamentally transform genetic analysis. We discuss these gene editing discoveries in the context of some of their likely social impacts.

Dalton Conley is the Henry Putnam University Professor of Sociology at Princeton University. His many books include Parentology: Everything You Wanted to Know about the Science of Raising Children but Were Too Exhausted to Ask. He lives in New York City. Jason Fletcher is Professor of Public Affairs, Sociology, Agricultural and Applied Economics, and Population Health Sciences at the University of Wisconsin–Madison. He lives in Madison. They are the authors of The Genome Factor: What the Social Genomics Revolution Reveals about Ourselves, Our History, and the Future.

The New Ecology

The New Ecology by Oswald J. SchmitzIn The New Ecology, Oswald Schmitz provides a concise guide to ecological thinking for an era in which the activity of one species—humans—has become the dominant influence on the environment, the Anthropocene. Much traditional ecological thinking has attempted to analyze the natural world in isolation from the social world of human life, regarding the human world as an external disturbance to the state of nature. The New Ecology seeks to bridge this nature/human divide and understand human life as an integral part of local and global ecosystems. In turn, it seeks also to recognize the scale of human influence on the environment and to promote an ethic of environmental stewardship, of responsible use and husbandry of the resources embodied in the ecosystem.

Two fields that might seem paradoxical areas of study for ecologists are industry and the city. One might think that the factory and the concrete jungle are as far removed from ecological concerns as one can get. However Schmitz points out that neither can be considered in isolation from either the natural world or the global economy, and that both can benefit from ecological thinking. Much modern industry is dependent on raw materials extracted through mining, raw materials which are necessarily finite in supply, meaning that in the long term these industries cannot be sustainable. Schmitz suggests that these industries could be reconfigured to mirror the cycles of food chains in which different organisms act to produce, to consume, and to decompose food to once again become raw material for the producers. To some extent, the practice of recycling follows this cycle, but we are a long way from recycling enough to supply all the raw materials needed for production. Massive quantities of these raw materials are being lost to landfill. One step in the right direction would be to design products with their ultimate decomposition in mind, to make it as easy as possible to break down and recycle the constituent materials. Taking things further, we can think of industries as making up complementary clusters in which, as in ecosystem food chains, the waste products from one industry become inputs for another. Schmitz notes the example of a development in Denmark in which “an electric power company, a pharmaceutical plant, a wall-board manufacturer, and an oil refinery exchange and use each other’s steam, gas, cooling water and gypsum residues.” (p.174) Another potential resource is the enormous quantities of raw materials embodied in our cities—could cities become the mines of the future?

Cities also need to be considered as their own distinct type of ecosystem. The urbanization of the global population continues; it is estimated that as much as 90% of the the world’s population will live in cities by the year 2100 (p.180). The sustainability of these cities will depend in part on the extent to which they can produce the materials needed for operation and minimize dependence on external resources. Thanks to ecological study we are increasingly aware of the vital role played by urban trees and greenspaces in filtering pollutants from the air, cooling the urban environment (in turn reducing energy use for cooling buildings), and controlling rainwater run-off. These unpaid services can be valued at hundred of thousands of dollars (p.184). But cities themselves form parts of larger systems, drawing on and affecting vast hinterlands, and often affecting distant parts of the globe in their demand for resources. Only through deepening our understanding of these complex interactions, including industrial and urban ecology, can we hope for long-term sustainability.

Browse Our Mathematics 2017 Catalog

Be among the first to browse our Mathematics 2017 Catalog:

If you are heading to the 2017 Joint Mathematics Meetings in Atlanta, Georgia from January 4 to January 7, come visit us at booth #143 to enter daily book raffles, challenge the SET grand master in a SET match, and receive a free copy of The Joy of SET if you win! Please visit our booth for the schedule.

Also, follow #JMM17 and @PrincetonUnivPress on Twitter for updates and information on our new and forthcoming titles throughout the meeting.

Fibonacci helped to revive the West as the cradle of science, technology, and commerce, yet he vanished from the pages of history. Finding Fibonacci is Keith Devlin’s compelling firsthand account of his ten-year quest to tell Fibonacci’s story.

Devlin Fibonacci cover

This annual anthology brings together the year’s finest mathematics writing from around the world. Featuring promising new voices alongside some of the foremost names in the field, The Best Writing on Mathematics 2016 makes available to a wide audience many articles not easily found anywhere else—and you don’t need to be a mathematician to enjoy them.

Pitici Best writing on Maths

In The Calculus of Happiness, Oscar Fernandez shows us that math yields powerful insights into health, wealth, and love. Using only high-school-level math, he guides us through several of the surprising results, including an easy rule of thumb for choosing foods that lower our risk for developing diabetes, simple “all-weather” investment portfolios with great returns, and math-backed strategies for achieving financial independence and searching for our soul mate.

Fernandez Calculus of Happiness

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Bird Fact Friday — Not so bird brained after all…

From page 161 of Bird Brain:

Bird Brain by Nathan Emery makes the case that birds are not as devoid of intelligence as has previously been thought. In fact, some can even be considered as smart as apes and dolphins. This concludes our Bird Fact Friday feature. Stay tuned for Horse Fact Friday starting in the new year!

Bird Brain
An Exploration of Avian Intelligence
Nathan Emery
With a foreword by Frans de Waal
Introduction

EmeryBirds have not been known for their high IQs, which is why a person of questionable intelligence is sometimes called a “birdbrain.” Yet in the past two decades, the study of avian intelligence has witnessed dramatic advances. From a time when birds were seen as simple instinct machines responding only to stimuli in their external worlds, we now know that some birds have complex internal worlds as well. This beautifully illustrated book provides an engaging exploration of the avian mind, revealing how science is exploding one of the most widespread myths about our feathered friends—and changing the way we think about intelligence in other animals as well.

Bird Brain looks at the structures and functions of the avian brain, and describes the extraordinary behaviors that different types of avian intelligence give rise to. It offers insights into crows, jays, magpies, and other corvids—the “masterminds” of the avian world—as well as parrots and some less-studied species from around the world. This lively and accessible book shows how birds have sophisticated brains with abilities previously thought to be uniquely human, such as mental time travel, self-recognition, empathy, problem solving, imagination, and insight.

Written by a leading expert and featuring a foreword by Frans de Waal, renowned for his work on animal intelligence, Bird Brain shines critical new light on the mental lives of birds.

Browse Our Physics & Astrophysics 2017 Catalog

We invite you to explore our Physics & Astrophysics 2017 Catalog:

PUP will be at the 229th Meeting of the American Astronomical Society in Grapevine, Texas from January 3 to January 7. Come and visit us at booth #200! Also, follow #AAS229 and @PrincetonUnivPress on Twitter for updates and information on our new and forthcoming titles throughout the meeting.

Welcome to the Universe is a personal guided tour of the cosmos by three of today’s leading astrophysicists: Neil deGrasse Tyson, Michael A. Strauss, and J. Richard Gott. Breathtaking in scope and stunningly illustrated throughout, this book is for those who hunger for insights into our evolving universe that only world-class astrophysicists can provide.

Tyson et al Welcome to the Universe

In Fashion, Faith, and Fantasy in the New Physics of the Universe, acclaimed physicist and bestselling author Roger Penrose argues that fashion, faith, and fantasy, while sometimes productive and even essential in physics, may be leading today’s researchers astray in three of the field’s most important areas—string theory, quantum mechanics, and cosmology.

Penrose Fashion

An accessible blend of narrative history and science, Strange Glow describes mankind’s extraordinary, thorny relationship with radiation, including the hard-won lessons of how radiation helps and harms our health. Timothy Jorgensen explores how our knowledge of and experiences with radiation in the last century can lead us to smarter personal decisions about radiation exposures today.

Jorgensen Strange Glow

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Bird Fact Friday – Do birds deceive one another?

From page 155 of Bird Brain:

For hundreds of years, con artists have tricked unsuspecting passerby with the shell game, in which a ball is placed under one of three shells and the participant must guess where the ball has ended up after the shells have been moved around. Scrub jays employ a similar tactic when they frequently recache food without necessarily moving the food each time. The trick is meant to deceive potential thieves.

Bird Brain
An Exploration of Avian Intelligence
Nathan Emery
With a foreword by Frans de Waal
Introduction

EmeryBirds have not been known for their high IQs, which is why a person of questionable intelligence is sometimes called a “birdbrain.” Yet in the past two decades, the study of avian intelligence has witnessed dramatic advances. From a time when birds were seen as simple instinct machines responding only to stimuli in their external worlds, we now know that some birds have complex internal worlds as well. This beautifully illustrated book provides an engaging exploration of the avian mind, revealing how science is exploding one of the most widespread myths about our feathered friends—and changing the way we think about intelligence in other animals as well.

Bird Brain looks at the structures and functions of the avian brain, and describes the extraordinary behaviors that different types of avian intelligence give rise to. It offers insights into crows, jays, magpies, and other corvids—the “masterminds” of the avian world—as well as parrots and some less-studied species from around the world. This lively and accessible book shows how birds have sophisticated brains with abilities previously thought to be uniquely human, such as mental time travel, self-recognition, empathy, problem solving, imagination, and insight.

Written by a leading expert and featuring a foreword by Frans de Waal, renowned for his work on animal intelligence, Bird Brain shines critical new light on the mental lives of birds.

Joshua Holden: The secrets behind secret messages

“Cryptography is all about secrets, and throughout most of its history the whole field has been shrouded in secrecy.  The result has been that just knowing about cryptography seems dangerous and even mystical.”

In The Mathematics of Secrets: Cryptography from Caesar Ciphers to Digital EncryptionJoshua Holden provides the mathematical principles behind ancient and modern cryptic codes and ciphers. Using famous ciphers such as the Caesar Cipher, Holden reveals the key mathematical idea behind each, revealing how such ciphers are made, and how they are broken.  Holden recently took the time to answer questions about his book and cryptography.


There are lots of interesting things related to secret messages to talk abouthistory, sociology, politics, military studies, technology. Why should people be interested in the mathematics of cryptography? 
 
JH: Modern cryptography is a science, and like all modern science it relies on mathematics.  If you want to really understand what modern cryptography can and can’t do you need to know something about that mathematical foundation. Otherwise you’re just taking someone’s word for whether messages are secure, and because of all those sociological and political factors that might not be a wise thing to do. Besides that, I think the particular kinds of mathematics used in cryptography are really pretty. 
 
What kinds of mathematics are used in modern cryptography? Do you have to have a Ph.D. in mathematics to understand it? 
 
JH: I once taught a class on cryptography in which I said that the prerequisite was high school algebra.  Probably I should have said that the prerequisite was high school algebra and a willingness to think hard about it.  Most (but not all) of the mathematics is of the sort often called “discrete.”  That means it deals with things you can count, like whole numbers and squares in a grid, and not with things like irrational numbers and curves in a plane.  There’s also a fair amount of statistics, especially in the codebreaking aspects of cryptography.  All of the mathematics in this book is accessible to college undergraduates and most of it is understandable by moderately advanced high school students who are willing to put in some time with it. 
 
What is one myth about cryptography that you would like to address? 
 
JH: Cryptography is all about secrets, and throughout most of its history the whole field has been shrouded in secrecy.  The result has been that just knowing about cryptography seems dangerous and even mystical. In the Renaissance it was associated with black magic and a famous book on cryptography was banned by the Catholic Church. At the same time, the Church was using cryptography to keep its own messages secret while revealing as little about its techniques as possible. Through most of history, in fact, cryptography was used largely by militaries and governments who felt that their methods should be hidden from the world at large. That began to be challenged in the 19th century when Auguste Kerckhoffs declared that a good cryptographic system should be secure with only the bare minimum of information kept secret. 
 
Nowadays we can relate this idea to the open-source software movement. When more people are allowed to hunt for “bugs” (that is, security failures) the quality of the overall system is likely to go up. Even governments are beginning to get on board with some of the systems they use, although most still keep their highest-level systems tightly classified. Some professional cryptographers still claim that the public can’t possibly understand enough modern cryptography to be useful. Instead of keeping their writings secret they deliberately make it hard for anyone outside the field to understand them. It’s true that a deep understanding of the field takes years of study, but I don’t believe that people should be discouraged from trying to understand the basics. 
 
I invented a secret code once that none of my friends could break. Is it worth any money? 
 
JH: Like many sorts of inventing, coming up with a cryptographic system looks easy at first.  Unlike most inventions, however, it’s not always obvious if a secret code doesn’t “work.” It’s easy to get into the mindset that there’s only one way to break a system so all you have to do is test that way.  Professional codebreakers know that on the contrary, there are no rules for what’s allowed in breaking codes. Often the methods for codebreaking with are totally unsuspected by the codemakers. My favorite involves putting a chip card, such as a credit card with a microchip, into a microwave oven and turning it on. Looking at the output of the card when bombarded 
by radiation could reveal information about the encrypted information on the card! 
 
That being said, many cryptographic systems throughout history have indeed been invented by amateurs, and many systems invented by professionals turned out to be insecure, sometimes laughably so. The moral is, don’t rely on your own judgment, anymore than you should in medical or legal matters. Get a second opinion from a professional you trustyour local university is a good place to start.   
 
A lot of news reports lately are saying that new kinds of computers are about to break all of the cryptography used on the Internet. Other reports say that criminals and terrorists using unbreakable cryptography are about to take over the Internet. Are we in big trouble? 
 
JH: Probably not. As you might expect, both of these claims have an element of truth to them, and both of them are frequently blown way out of proportion. A lot of experts do expect that a new type of computer that uses quantum mechanics will “soon” become a reality, although there is some disagreement about what “soon” means. In August 2015 the U.S. National Security Agency announced that it was planning to introduce a new list of cryptography methods that would resist quantum computers but it has not announced a timetable for the introduction. Government agencies are concerned about protecting data that might have to remain secure for decades into the future, so the NSA is trying to prepare now for computers that could still be 10 or 20 years into the future. 
 
In the meantime, should we worry about bad guys with unbreakable cryptography? It’s true that pretty much anyone in the world can now get a hold of software that, when used properly, is secure against any publicly known attacks. The key here is “when used properly. In addition to the things I mentioned above, professional codebreakers know that hardly any system is always used properly. And when a system is used improperly even once, that can give an experienced codebreaker the information they need to read all the messages sent with that system.  Law enforcement and national security personnel can put that together with information gathered in other waysurveillance, confidential informants, analysis of metadata and transmission characteristics, etc.and still have a potent tool against wrongdoers. 
 
There are a lot of difficult political questions about whether we should try to restrict the availability of strong encryption. On the flip side, there are questions about how much information law enforcement and security agencies should be able to gather. My book doesn’t directly address those questions, but I hope that it gives readers the tools to understand the capabilities of codemakers and codebreakers. Without that you really do the best job of answering those political questions.

Joshua Holden is professor of mathematics at the Rose-Hulman Institute of Technology in Terre Haute, IN. His most recent book is The Mathematics of Secrets: Cryptography from Caesar Ciphers to Digital Encryption.

Exclusive interview with Neil deGrasse Tyson, Michael A. Strauss, and J. Richard Gott on their NYT bestseller, Welcome to the Universe

UniverseWe’re thrilled to announce that Welcome to the Universe, a guided tour of the cosmos by three of today’s leading astrophysicists, recently made the New York Times extended bestseller list in science. Inspired by the enormously popular introductory astronomy course that Neil deGrasse Tyson, Michael A. Strauss, and J. Richard Gott taught together at Princeton, this book covers it all—from planets, stars, and galaxies to black holes, wormholes, and time travel. The authors introduce some of the hot topics in astrophysics in today’s Q&A:


What is the Cosmic Perspective?

NDT: A view bigger than your own that offers a humbling, yet enlightening, and occasionally empowering outlook on our place as humans in time, space, on Earth and in the Universe. We devote many pages of Welcome to the Universe to establishing our place in the cosmos – not only declarations of that place, but also the reasons and the foundations for how we have come to learn how we fit in that place. When armed with a cosmic perspective, many earthly problems seem small, yet you cultivate a new sense of belonging to the universe. You are, in fact, a participant in the great unfolding of cosmic events.

What are some of the takeaways from the book?

NDT: If you read the entire book, and if we have succeeded as authors, then you should walk away with a deep sense of the operations of nature, and an appreciation for the size and scale of the universe; how and why planets form; how and why we search for planets orbiting around other stars, and alien life that may thrive upon them; how and why stars are born, live out their lives and die; what galaxies are and why they are the largest organizations of stars in the universe; the large scale structure of galaxies and space-time; the origins and future of the universe, Einstein’s relativity, black holes, and gravitational waves; and time travel. If that’s not enough, you will also learn about some of the continued unsolved mysteries in our field, such as dark matter, dark energy, and multiverses.

This book has more equations than do most popular books about astrophysics.  Was that a deliberate decision?

MAS: Yes.  The book’s subtitle is “An Astrophysical Tour,” and one of our goals in writing it was to show how observations, the laws of physics, and some high school mathematics can combine to yield the amazing discoveries of modern astrophysics: A Big Bang that happened 13.8 billion years ago (we show you how that number is determined), the dominant role dark matter has in the properties of galaxies (we tell you how we came to that conclusion), even the fact that some planets orbiting other stars have conditions conducive for liquid water to exist on their surface, thought to be a necessary prerequisite for life. Our goal is not just to present the wonders of the universe to the reader, but to have the reader understand how we have determined what we know, and where the remaining uncertainties (and there are plenty of them!) lie.

So your emphasis is on astrophysics as a quantitative science, a branch of physics?

MAS:  Yes.  We introduce the necessary physics concepts as we go: we do not expect the reader to know this physics before they read the book.  But astrophysicists are famous (perhaps notorious!) for rough calculations, “to astrophysical accuracy.”  We also lead the reader through some examples of such rough calculations, where we aim to get an answer to “an order of magnitude.”  That is, we’re delighted if we get an estimate that’s correct to within a factor of 2, or so.  Such calculations are useful in everyday life, helping us discriminate the nonsensical from the factual in the numerical world in which we live.

Can you give an example?

MAS: Most people in everyday discourse don’t think much about the distinction between “million,” “billion,” “trillion,” and so on, hearing them all as “a really big number,” with not much difference between them.  It is actually a real problem, and the difference between Federal budget items causing millions vs. billions of dollars is of course huge.  Our politicians and the media are confusing these all the time.  We hope that the readers of this book will come away with a renewed sense of how to think about numbers, big and small, and see whether the numbers they read about in the media make sense.

Is time travel possible?

JRG: In 1905 Einstein proved that time travel to the future is possible. Get on a rocket and travel out to the star Betelgeuse 500 light-years away and return at a speed of 99.995 % the speed of light and you will age only 10 years, but when you get back it will be the year 3016 on Earth. Even though we have not gone that fast or far, we still have time travelers among us today. Our greatest time traveler to date is the Russian cosmonaut Gennady Padalka, who by virtue of traveling at high speed in low Earth orbit for 879 days aged 1/44 of a second less than if he had stayed home. Thus, when he returned, he found Earth to be 1/44 of a second to the future of where he expected it to be. He has time traveled 1/44 of a second to the future. An astronaut traveling to the planet Mercury, living there for 30 years, and returning to Earth, would time travel into the future by 22 seconds. Einstein’s equations of general relativity, his theory of curved spacetime to explain gravity, have solutions that are sufficiently twisted to allow time travel to the past. Wormholes and moving cosmic strings are two examples. The time traveler can loop back to visit an event in his own past. Such a time machine cannot be used to journey back in time before it was created. Thus, if some supercivilization were to create one by twisting spacetime in the year 3000, they might use it to go from 3002 back to 3001, but they couldn’t use it go back to 2016, because that is before the time loop was created. To understand whether such time machines can be realized, we may need to understand how gravity works on microscopic scales, which will require us to develop a theory of quantum gravity. Places to look for naturally occurring time machines would be in the interiors of rotating black holes and at the very beginning of the universe, where spacetime is strongly curved.

Do we live in a multiverse?

JRG: A multiverse seems to be a natural consequence of the theory of inflation. Inflation explains beautifully the pattern of slightly hotter and colder spots we see in the Cosmic Microwave Background Radiation. It explains why the universe is so large and why it is as smooth as it is and still has enough variations in density to allow gravity to grow these into galaxies and clusters of galaxies by the present epoch. It also explains why the geometry of the universe at the present epoch is approximately Euclidean. Inflation is a period of hyperactive accelerated expansion occurring at the beginning of our universe. It is powered by a large vacuum energy density and negative pressure permeating empty space that is gravitationally repulsive. The universe doubles in size about every 3 10-38 seconds. With this rate of doubling, it very quickly grows to enormous size: 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024… That explains why the universe is so large. When the high density vacuum state decays, it doesn’t do so all at once. Like water boiling in a pot, it does not turn into steam all at once, but should form bubbles. Each expanding bubble makes a universe. The inflationary sea should expand forever, creating an infinite number of bubble universes, ours being one of them. Other distant bubble universes are so far away, and the space between us and them is expanding so fast, that light from them may never reach us. Nevertheless, multiple universes seem a nearly inevitable consequence of inflation.

What discovery about the universe surprises or inspires you the most?

JRG: Perhaps the most amazing thing about the universe is that it is comprehensible to intelligent, carbon-based life forms like ourselves. We have been able to discover how old the universe is (13.8 billion years) and figure out many of the laws by which it operates. The object of this book is to make the universe comprehensible to our readers.

Don’t miss this C-Span video on the book, in which the authors answer questions about the universe, including how it began and the likelihood of intelligent life elsewhere.

Neil deGrasse Tyson is director of the Hayden Planetarium at the American Museum of Natural History. He is the author of many books, including Space Chronicles: Facing the Ultimate Frontier, and the host of the Emmy Award–winning documentary Cosmos: A Spacetime Odyssey. Michael A. Strauss is professor of astrophysics at Princeton University. J. Richard Gott is professor of astrophysics at Princeton University. His books include The Cosmic Web: Mysterious Architecture of the Universe (Princeton).