Invisibility cloak unveiled!

Awful pun in the title, sorry! So here is the news. Scientists at Rochester have invented – well, not quite invented, but significantly improved over old versions – a device which works as an invisibility cloak. The new approach not only results in better concealment of the object, but can also use cheaper materials. In fact, you can even make your own using 4 lenses! Read the full article (from which I took the Rochester cloak building instructions and the image below) here. If you or your university has a subscription to the OpticsInfoBase journal, you can read the mathematical basis of the cloak. I love the title of the paper. I bet they enjoyed writing it.

J. C. Howell, J. B. Howell, and J. S. Choi, “Amplitude-only, passive, broadband, optical spatial cloaking of very large objects,” Appl. Opt. 53, 1958-1963 (2014), URL:

lens diagram

  1. Purchase 2 sets of 2 lenses with different focal lengths f1 and f2 (4 lenses total, 2 with f1 focal length, and 2 with f2 focal length)
  2. Separate the first 2 lenses by the sum of their focal lengths (So f1 lens is the first lens, f2 is the 2nd lens, and they are separated by t1= f1+f2).
  3. Do the same in Step 2 for the other two lenses.
  4. Separate the two sets by t2=2 f2 (f1+ f2) / (f1 f2) apart, so that the two f2 lenses are t2 apart.


Earlier this year, scientists from the University of Central Florida made the news with the first large-scale invisibility cloaking device. Here is their paper in Advanced Optical Materials:

Li Gao, Youngmin Kim, Abraham Vazquez-Guardado, Kazuki Shigeta, Steven Hartanto, Daniel Franklin, Christopher J. Progler, Gregory R. Bogart, John A. Rogers, and Debashis Chanda, Negative Index Materials: Materials Selections and Growth Conditions for Large-Area, Multilayered, Visible Negative Index Metamaterials Formed by Nanotransfer Printing (Advanced Optical Materials 3/2014)'s_Stone

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Crazy constructible polygons

Read on Prof Ian Stewart’s Twitter (@JoatStewart):

“Regular 618046320536701272583608037733434096317263320037227965361869850786715388113584129-gon is constructible with ruler compass & trisector

So is 756760676272923020551154471073240459834492063891235892290277703256956240171581788957704193-gon. 90-digit prime!

However, regular 11-gon is not constructible with ruler, compass, and angle-trisector. Next impossible cases 22, 23, 25, 29.

It gets crazier. Gleason conjectured there are infinitely many primes of form 2^c.3^d+1. About 9k with k digits or less”


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Edinburgh Scientist Fergus McInnes Missing [in Switzerland?]

An unusual and serious post.

Fergus McInnes, 51, scientist from the School of Informatics, Edinburgh University, is missing. He boarded a flight to go to a conference in Switzerland but did not check into his hotel, attend the conference, or board his return flight. He has not been seen or heard from since.

(read more)

If you have any information about Fergus McInnes’ whereabouts, please contact the police.

Why are Indians so good at code?

Cheryll Barron offers a historical explanation:

“Indian software aptitude rests on an unlikely pair of factors: an emphasis on learning by rote in Indian schools, and a facility and reverence for abstract thought. These biases of Indian education are all but mutually exclusive in the modern West, where a capacity for abstraction is closely associated with creativity and stimulating, inspirational learning. In India, learning by rote is seen by many, if not most conventional teachers, as essential grounding for creativity – like Picasso’s mastery of perspective and anatomy in his youth – and for unbounded invention and speculation.”

from: “The Indian genius

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A two-body problem (cryptic short story)

A friend wrote this short story on the two-body problem. It’s rather cryptic, but it is about love and maths…


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The slaves-who-are-masters of Silicon Valley

Silicon Valley: an army of geeks and ‘coders’ shaping our future” (click on the title to read article)

A vivid, if somewhat sensationalist, description of Silicon Valley by a non-coder, highlightting a bunch of interesting issues – the historical importance of the computer revolution, power, the drive to innovation and its directions, gender, age, work ethics…

“An ad in the back of the main San José listings magazine reads: “Computer Systems Analyst, Sunnyvale, CA. Bachelor and five years experience required.” What is this place? [...] for all we see and hear about the Valley’s gilded apps and networks, glimpses of the people behind them are rare. Who are they and what does the society they have made for themselves (the template for our own) look like by light of day?”

Andrew Smith, The Guardian, 11 May 2014

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Family Maths Day in Berlin: 6 September, Saturday!


Was für eine tolle Idee: ein Mathe-Familien-Tag! Das Fest findet am Samstag, 6.September, von 14 bis 18 Uhr im Schulgarten Moabit statt. Der Eintritt ist frei. Mehr Infos hier und hierMathe-Familien-Tag am 6.9. in BerlinMathe-Familien-Tag 2014Mathe-Familien-Tag 2014

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IMAGINARY exhibition

Just discovered something super cool. The IMAGINARY platform ( grew out of an exhibition organised in 2008.
Here is some awesome mathematical eye candy

Quasicrystalline Wickerwork, by Uli Gauenshirt Source:

Quasicrystalline Wickerwork, by Uli Gauenshirt

FT: “The North needs to retain its science graduates”

According to a new report, tech startups are disproportionately concentrated in the UK’s south. Unsurprising, really. Some analysis and (a small number of) counterexamples here –  article byBy Murad Ahmed and Chris Tighe

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