## Posts Tagged ‘**Prime number**’

## Prime News!…

Readers will know that this space follows the hunt for new prime numbers, and more particularly, for new “Mersenne primes.”

Now, as ArsTechnica reports:

A new largest prime number has been discovered, mersenne.org reported Tuesday. 2

^{57,885,161}-1, which is also the 48^{th}Mersenne prime, was discovered on the computer of Dr. Curtis Cooper, a professor at the University of Central Missouri.A Mersenne prime is a prime number that can be written in the form M

_{p}= 2^{n}-1, and they’re extremely rare finds. Of all the numbers between 0 and 25,964,951 there are 1,622,441 that are prime, but only 42 are Mersenne primes.The 48

^{th}Mersenne prime was discovered as part of the Great Internet Mersenne Prime Search (GIMPS), a project that has used volunteer computers to calculate and search for primes for 17 years. Dr. Cooper’s computer took 39 days of continuous calculation to verify the prime status of the number, which has over 17 million digits…

Read the full story here; the report from Mersenne.org here; and visit the Mersenne/GIMPS homepage here.

###

**As we regret the limited number of fingers and toes with which we were born,** we might recall that it was on this date in 1946 that the first ancestor of Dr. Cooper’s computer– the ENIAC (Electronic Numerical Integrator And Computer)– was first demonstrated in operation. (It was announced to the public te following day.) The first general-purpose computer (Turing-complete, digital, and capable of being programmed and re-programmed to solve different problems), ENIAC was begun in 1943, as part of the U.S’s war effort (as a classified military project known as “Project PX”); it was conceived and designed by John Mauchly and Presper Eckert of the University of Pennsylvania, where it was built. The finished machine, composed of 17,468 electronic vacuum tubes, 7,200 crystal diodes, 1,500 relays, 70,000 resistors, 10,000 capacitors and around 5 million hand-soldered joints, weighed more than 27 tons and occupied a 30 x 50 foot room– in its time the largest single electronic apparatus in the world. ENIAC’s basic clock speed was 100,000 cycles per second. Today’s home computers have clock speeds of 1,000,000,000 cycles per second; Dr, Gordon’s, much faster still.

## Tabletop science…

source: RSC

Two bulletins…

First, from * New Scientist*:

An electromagnetic “black hole” that sucks in surrounding light has been built for the first time. The device, which works at microwave frequencies, may soon be extended to trap visible light, leading to an entirely new way of harvesting solar energy to generate electricity.

A theoretical design for a table-top black hole to trap light was proposed in a paper published earlier this year by Evgenii Narimanov and Alexander Kildishev of Purdue University in West Lafayette, Indiana. Their idea was to mimic the properties of a cosmological black hole, whose intense gravity bends the surrounding space-time, causing any nearby matter or radiation to follow the warped space-time and spiral inwards.

Narimanov and Kildishev reasoned that it should be possible to build a device that makes light curve inwards towards its centre in a similar way… Now Tie Jun Cui and Qiang Cheng at the Southeast University in Nanjing, China, have turned Narimanov and Kildishev’s theory into practice, and built a “black hole” for microwave frequencies…

More (including a cool video) at * New Scientist*.

Then, from * Network World*:

A

12 million digit prime number, the largest such number ever discovered, has landed a voluntary math research group a $100,000 prize from the Electronic Frontier Foundation (EFF).The number, known as a Mersenne prime, is the 45th known Mersenne prime, written shorthand as 2 to the power of 43,112,609, minus 1 . A Mersenne number is a positive integer that is one less than a power of two, the group stated.

The computing project called the Great Internet Mersenne Prime Search (GIMPS) made the discovery on a computer at the University of California, Los Angeles (UCLA) Mathematics Department. Computing manager Edson Smith installed and maintained the GIMPS software at UCLA, and thousands of other volunteers also participated in the computation…

More at * Network World*.

(Readers may recall that **(R)D reported last March **on GIMP and the effort to find the next Mersenne Prime– at which point the estimation was that it might stretch to a mere 10 million digits. Clearly, GIMP’s over-achievement affirms its worthiness of the EFF award.)

**As we channel Mr. Wizard**, we might run a celebratory riff for Charles Edward Anderson “Chuck” Berry, born on this date in 1926– Hail, Hail, Rock and Roll!

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