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Free for the next couple of days: my book

My job went away a few months back and am working towards finding another one. Still it’s the season of giving, so I wanted to share something; all I have is this little kinda-corny ebook I published on amazon, so I thought “Hell, I can give it away - someone might enjoy it...” Here ya go - free for the next few days, across multiple countries.

US: http://www.amazon.com/gp/product/B013XZ63FO

UK:http://www.amazon.co.uk/gp/product/B01... 

DE:http://www.amazon.de/gp/product/B01... 

FR:http://www.amazon.fr/gp/product/B01...

ES:http://www.amazon.es/gp/product/B01... 

IT:http://www.amazon.it/gp/product/B01... 

NL:http://www.amazon.nl/gp/product/B01... 

JP:http://www.amazon.co.jp/dp/B013XZ63FO 

BR:http://www.amazon.com.br/gp/product/B01... 

CA:http://www.amazon.ca/gp/product/B01... 

MX:http://www.amazon.com.mx/gp/product/B01... 

AU:http://www.amazon.com.au/gp/product/B01... 

IN:http://www.amazon.in/gp/product/B01... 

A bit about it: It’s not the next Moby Dick, nor Harry Potter, but it’s something. A cheesy something, cheesy in a United-Colors-of-Benetton-Meets-adult-Harry-Potter-If-He-Was-An-African-American-Woman sort of way.

The bullet: Jasmine Cowl is pissed. Fifteen years ago, the young woman and a group of her friends had managed to save the world. Now she’s stuck in a boring, mundane life, in spite of the fact that she works for the CIA... not that CIA, the other one. Saddled with a family, a job, and the PTA, she thinks she’s found a new threat. Disgruntled gnomes, talking islands, and a car that seems to have taken a life of its own force themselves into Jasmine’s life as a hunt for a powerful wand turns her life inside out. This time she’s fighting for more than the fate of the world. This time she’s fighting for her kids.

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FRBs...



This artist's impression of a fast radio burst (FRB) reaching Earth illustrates the telltale smearing of radio waves that indicates the FRB's long journey through deep space. The colors represent different radio wavelengths, with longer (red) wavelengths arriving after shorter (blue) ones. This effect occurs when radio waves travel through plasma-rich regions of interstellar and intergalactic space.

Credit: Jingchuan Yu, Beijing Planetarium

Topics: Astrophysics, Radio Astronomy, Research, Space Exploration


What shines brighter than the Sun, appears for only a split second and lights up Earth’s skies thousands of times each day?

If you’re stumped, don’t worry—experts are too. For nearly a decade, astrophysicists have been struggling to explain perplexing millisecond chirps of radio waves pinging through the heavens. Now, several new studies are bringing researchers closer to solving the mystery by narrowing the search for the radio flashes’ origins to youthful stellar outbursts in distant galaxies.

Dubbed “fast radio bursts,” or FRBs, the first of these bright, brief events was announced in 2007 by the West Virginia University astrophysicist Duncan Lorimer and colleagues, based on data from the Parkes radio telescope in Australia. The radio signal that streamed into the Parkes dish was curiously smeared out, with its high-frequency waves arriving a fraction of a second earlier than its low-frequency counterparts—an effect attributed to scattering by diffuse plasmas that fill interstellar and intergalactic space. The more smeared a radio signal is, the more plasma it has passed through, and the farther it has presumably traveled through space. Analyzing the smear, Lorimer and his collaborators made a rough estimate that the burst could’ve come from up to a few billion light-years away. If they were in fact coming from so far away, and if more could be found, FRBs offered a way for astronomers to better measure vast cosmological distances and to probe deeper into the dark spaces between stars and galaxies. The search was on.

Scientific American: Fast Radio Bursts Mystify Experts—for Now, Lee Billings

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The Brown Condor of Ethiopia.

I was going thru some old papers and came across a really yellowed newspaper page, tattered and folded. The Plain Dealer Tuesday August 23 1988 page 11Ae. The article was about John Charles Robinson, aviator. An extraordinary airman dubbed "the Brown Condor". He leaped off the ground in Mississippi and didn't land until he made history. Here is a pic from the net.

 Check out his story, pretty cool. The Brown Condor of Ethiopia, John C. Robinson was personal pilot of Emperor Haile 

Selassie and established an Ethiopian airline. Inspiring no doubt.

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Orbital WALL-E...

Image Source: Figure 3 Debris engine, see link below


Topics: Astrophysics, Instrumentation, Space, Space Junk, Taikonaut


I am always glad when good science is proposed and achieved. This is mostly a thorough application of Kepler and Newtonian physics as well as engineering rocketry. I give the poignant observation with some exception, this is happening LESS in the country of my birth, currently known for carnival barkers and xenophobes as presidential front runners, and some of my fellow citizens thinking "The Flintstones" instead of a parody of "The Honeymooners" was a documentary.

TECHNOLOGY REVIEW: At 16:56 UTC on August 29, 2009, an Iridium communications satellite suddenly fell silent. In the hours that followed, the U.S. Space Surveillance Network reported that it was tracking two large clouds of debris—one from the Iridium and another from a defunct Russian military satellite called Cosmos 2251.

The debris was the result of a high-speed collision, the first time this is known to have happened between orbiting satellites. The impact created over 1,000 fragments greater than 10 centimeters in size and a much larger number of smaller pieces. This debris spread out around the planet in a deadly cloud.

Space debris is a pressing problem for Earth-orbiting spacecraft, and it could get significantly worse. When the density of space debris reaches a certain threshold, analysts predict that the fragmentation caused by collisions will trigger a runaway chain reaction that will fill the skies with ever increasing numbers of fragments. By some estimates that process could already be underway.

An obvious solution is to find a way to remove this debris. One option is to zap the larger pieces with a laser, vaporizing them in parts and causing the leftovers to deorbit. However, smaller pieces of debris cannot be dealt with in this way because they are difficult to locate and track.

Another option is send up a spacecraft capable of mopping up debris with a net or some other capture process. But these missions are severely limited by the amount of fuel they can carry.

Today, Lei Lan and pals from Tsinghua University in Beijing, China, propose a different solution. Their idea is to build an engine that converts space debris into propellant and so can maneuver itself almost indefinitely as it mops up the junk.

Physics arXiv: Debris Engine: A Potential Thruster for Space Debris Removal
Lei Lan, Jingyang Li, Hexi Baoyin

#P4TC WALL-E mentions:
Predicted, but still kind of gross when you think of it...
NASA Going Green...

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‘The Flash’ Finds its Wally West in ‘Insurgent’ Star Keiynan Lonsdale

The Flash” has cast Australian actor Keiynan Lonsdale as Wally West, the iconic speedster from the DC Comics universe who made his debut as Kid Flash. He’ll appear as a series regular in season two.

In comics canon, Wally is the nephew of Iris West (played in The CW series by Candice Patton) — the love interest and eventual wife of Barry Allen (Grant Gustin). While Wally initially served as his uncle’s sidekick and a founding member of the Teen Titans, he later inherited Barry’s mantle as The Flash.

Since Iris doesn’t seem to have any siblings on the show (that we know of), it’s possible that Wally’s origin story will be tweaked for his live-action “Flash” debut. His connection to the West family has yet to be confirmed.

http://variety.com/2015/tv/news/the-flash-wally-west-keiynan-lonsdale-1201557295/

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This taken from the article posted on COMICBOOK.COM 12/02/2015

Adult Swim has just announced a new season of Samurai Jack to launch in 2016. The show will return during Adult Swim's Toonami block and is currently in production in Los Angeles.

You read that right folks, the 4 time Primetime Emmy Award winning series that has its roots in the early 2000's is back! Samurai Jack, created by Genndy Tartakovsky follows Jack, a samurai who travelled through time with the quest to head back to where he came from and defeat the demon Aku.

The show ended in 2004 but not before cultivating a die hard fanbase that has been clamoring for it's return for just over 10 years. Fans looking for their Jack fix got a small taste in comic form, thanks to IDW.

"I feel like it's culminating to a fever pitch almost." said Tartakovsky in a previous interview with ComicBook.com. "I feel like it's time to maybe finish the story. We've been trying to get the feature off the ground but maybe that's just fate's way of saying this is a television thing and maybe it should be a mini-series or something like that."

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 Ok Y'all, just add me to the list of peeps diggin' on Marcus Williams and Greg Burnham's TUSKEGEE HEIRS. Will offer what support I can because THIS is the type of thought, actions and deeds that our creative energies should be focusing on.

 

From the Facebook postings of Greg Burnham and Marcus Williams and their TUSKEGEE HEIRS Group.....

 

""Introducing "Tuskegee Heirs"


Synopsis:


Tuskegee Heirs is a futuristic sci-fi adventure that follows a small squadron of young gifted aviators who are forced to become earth’s last line of defense against a highly advanced military faction bent on destroying civilization as we know it.


Had this concept in my head for a bit and after some wonderful confirmation bestowed this weekend passed(speaking with some awesome kids), I know this needs to happen. The homie Greg Burnham and I will be pumping out the creative juices to bring this to as many eyes as possible in the near future...."

 

I say INDEED to the brothers who has taken a ROBOTECH-esque approach to a historical, AFRICAN AMERICAN institution and gave a it a DIFFERENT life's breath.

 

 

 This has the Spirit of Hip Hop all through it. Something old, creating something new, something borrowed and I will assume the something blue will be the storylines this create team will offer. LOL and to clarify what I mean by "something blue" old school description of Life's problems. Blessings Brothers.

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US Asylum...

Previously unpublished poem by Carl Sandburg

Topics: Commentary, Politics, Sandy Hook


A departure from physics and society...for a moment.

The physics of bullets has now killed more people with the San Bernardino shooting than we have days in the year. Another one happened simultaneously in Georgia - one woman died, but still someone's one. A third one at a Target. San Bernardino is second only to Sandy Hook, and once we got over that as I've said, "it was a wrap!"*

The NRA (not responsible anytime) will respond with their usual: crickets, hunkered down under their moist rock until our news feeding frenzy blows over. This will "not be a time" to discuss a change in laws or even keeping statistics to study. We're afraid of Syrian refugees, yet the armed, short-phallic members of the NRA and their lobby have INSURED terrorists can legally purchase firearms. Black Friday when Mr. Dear shot up Planned Parenthood in Colorado, there was a massive purchase of guns. Perhaps the ones used yesterday in California. Anyone that hasn't committed a crime can pass a background check that doesn't ask if you're on Valium or Xanax.

We have 20X the gun rate murders than any similarly developed nation. An Australian baseball player lost his life in Texas...here on SCHOLARSHIP to bored teens!

There is no doubt about it: we are the United Sanitarium Asylum. We're not "states" except the state of mental illness, paranoia, misogyny, racism, sexism; xenophobia. Conspiracy carnival barkers will howl at the moon. Counting down until Alex Jones invariably calls this a "false flag operation." He'll sell a lot of hurriedly produced DVDs (we didn't have to wait long). Flaccid, feckless, impotent lawmakers not worthy of the oath they took to "protect and defend" The Constitution against all enemies, foreign and DOMESTIC will simultaneously Tweet their "thoughts and prayers" and call for less gun-free zones as their financiers/benefactors have scripted them to say. They'll otherwise do NOTHING since their gated neighborhoods have tactical guards armed-to-the-teeth to protect them and their families. Yours and mine are cannon fodder.

I think...we need a fence. Not just a Trump fence on the Texas-Mexico border, but across the Northern Canadian border.

We need a UN naval blockade on the East Coast and as far out as Hawaii and as north as Alaska.

We need to broadcast a travel advisory to the planet:

DANGER! The USA is hazardous to your health. A worldwide quarantine is ordered. Travel to America AT YOUR OWN RISK!

Lastly, we need to offer Visas to the sane of us that just want out.

Time, their own arsenals and Darwin will take care of the idiots left!
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Cynicism...

Haze from coal and other fossil fuels dims the sky in Changchun, China. WANG ZHE - IMAGINECHINA
Image Source: Science Mag Link Below


Topics: Climate Change, Economy, Global Warming, Green Energy, Jobs, STEM


Our record-hated congress spent the early part of November putting legislation in place to block any climate actions currently being decided by the rest of the planet in Paris, France. They've had a blithe record of "do-nothing" for quite some time now. It's the political equivalent of cutting one's index finger off to cause a heart attack in an opponent. Voodoo without the economics...

Here's my cynicism, if I think purely of myself:

- I'll likely not be alive when the United States becomes a majority-minority (read: non-white) nation. Neither will the people who spend their addled time on Xanax in chat rooms and conspiracy provocateur meetings that consume salted potato chips and BTUs in naval gazing. We'll all be dust.

- I definitely won't be alive in the year 2100 when the climate you-know-what quite literally "hits the fan."

So, why should I care?

I honestly think this is the meditation of deniers. They won't be here. None of us will.

Here's the growth formula: N = N0 * ert.

Humans, animals and bacteria are remarkable in their similar modeling.

Let N0 = 7 billion; r (growth rate) = 0.01; t = 35 years, I get: 9,933.472,840.15. Round up to 10 billion in the year 2050.

Eighty-five years from now you get 16,377,527,963.48 in 2100. More than double; the planet doesn't get any bigger. That's a lot of mouths to feed; a lot of carbon dioxide exhaled; less trees and more poop to dispose of (methane is another greenhouse gas).

I don't care. Really I can't. I won't be here. That's three generations from now.

China's air will be just as ducky as it was today if not more so. The current haze prematurely kills 350,000 to 500,000 persons, and I'm sure by 2050 they will "improve" on those numbers.

The Dodo is no longer here. Neither are a lot of other species. Neither will eventually be any of us...maybe all of us.

Eventually the weather will be too extreme to have predictable planting seasons, agriculture for better or worse being the bedrock of modern civilization. Swaths of the planet will not be able to feed themselves. You may be able to "trim the fat" (which I suspect a lot will not have in the bodily sense), or "reduce the herd." Weapons manufacturers will do what they do in poor countries with the resources to buy their wares to invade even poorer countries; "Peace on Earth" obviously not in the business model. There will be liberty, freedom and sectarian conflicts. Mansions in gated communities will have to become fortresses with ye olden moats and maybe a few crocodiles to keep out the riffraff, or as the Statue of Liberty currently describes "the huddled masses," yearning in this instance to eat anything...or, anyone. They could all 1 and 99% take a whiff of the thick, rancid air.

But hey! Join me. We'll be atomized and this struggle will be for our great grandchildren. They could discover "warp drive"...or have a warped end.

MIT Technology Review
Wealthy Investors Target Dramatic Increase in Clean-Energy Funding, Richard Martin
Why Solar Power Could Hit a Ceiling, Mike Orcutt

#P4TC: Ragnarok...

Science Mag: Choosing a climate future in Paris, Eli Kintisch

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Qubits @ Room...

Physicists create many entangled states of electrons ("e") and nuclei ("n") in the industrially important semiconductor silicon carbide, all at ambient conditions. (Courtesy: Paul Klimov, University of Chicago)

Topics: Entanglement, Semiconductor Technology, Quantum Computer, Quantum Mechanics

The quantum entanglement of a large ensemble of spins in a semiconductor has been carried out at room temperature for the first time, by researchers in the US. The team entangled more than 10,000 copies of two-qubit entangled states in a commercial silicon-carbide (SiC) wafer at ambient conditions. SiC is widely used in electronics, so this latest achievement could be an important step towards the creation of sophisticated quantum devices that harness entanglement.

Entanglement is a purely quantum-mechanical phenomenon that allows two or more particles to have a much closer relationship than is allowed by classical physics, no matter how far apart they may be. The states of entangled particles are inextricably linked such that any change made to one particle instantly influences the state of the other. Entangled particles are seen as a key component of quantum computers, but for entanglement to be truly utilized in practical applications, researchers must be able to entangle quantum bits (qubits) at room temperature and preserve the entangled state.

Physics World: Physicists entangle qubits in a semiconductor at room temperature
Tushna Commissariat

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Luddites...

Image Source: Smithsonian.com. Ludd, drawn here in 1812, was the fictitious leader of numerous real protests. (Granger Collection, New York)


Topics: Alternative Energy, Climate Change, Economy, Jobs, Politics, Research, STEM


Researching the term Luddite was quite revealing. Ned Lud (or Ludd/Ludham) appears to have been a fiction concocted to coincide with the legend Robin Hood of Sherwood Forest and the "righteousness" of the protesters' cause 1. First of all, they weren't so opposed to technology as most have defined them over time. Their opposition to the technology of the stocking frame appeared to be what is angering swaths of humanity now: increased productivity that has not been - especially lately - proportional to increased wages or employment.

Thus everyone is taken aback at the impotence of self-governance, which is the hallmark of democratic republics. We do not salute a king, we essentially elect our leaders to do the will of the people who sent them to office, leaders often swayed more by the uber class that invest in their election campaigns; less by their "neighbors" they haven't lived next to in quite some time.

Free trade: most of them have been bandied as cause De Jure by some politicians and ignored by others. "Bring the jobs back" seems a simple solution that begs two questions: 1. Even if the jobs came back, would Americans line up and apply for them? 2. What if our modern "stocking frame" of convenient technology and mobile apps doesn't allow the previous jobs to come back?

I receive as member of the American Physics Society its newsletter. In the print issue of Inside the Beltway I read 2, Michael S. Lubell posits the question: "Does Science Bear Any Responsibility for Today’s Political Discontent?" He points out through science there's been an increase in productivity that up until recent history tracked well with wages and jobs. However, from the article:

A new Economic Policy Institute report provides a possible clue. Josh Bivens and Lawrence Mishel, the report’s authors, took a hard look at the impact of productivity, defined as economic output per unit input (e.g., labor and capital); on a typical worker’s compensation. What they detail is profoundly disturbing.

Bivens and Mishel trace the history of productivity and compensation from 1948 to the present. During the first 25 years, hourly compensation fairly tracked gains in productivity, rising 91.3 percent during that period while productivity, driven in large part by technological advances, rose 96.7 percent. But from 1973 through 2014, while productivity continued to soar, rising another 72.2 percent, compensation grew by a paltry 9.2 percent.

In short, during those four decades, the average worker stopped benefiting from science and technology’s largess. But corporations did not: their profits rose dramatically, and their stock prices soared. Between the beginning of 1973 and the end of 2014, for example, the Dow Jones Industrial Average, adjusted for inflation, rose 216 percent.

I do have concerns. Again from APS, the latest new report in the under-representation of African Americans in the Physical Sciences 3. There's concern with women 4 being in a fluctuating but representative small number. Both and other groups has to do with exposure and family income: if your parents are in STEM, you're more likely to follow them; in most cases, you are more likely to run experiments in your room if you can afford them and your neighborhood environment feels safe to do so.

We've gone from "Rosie the Riveter" to "Rosie the Robot Maintainer"; "Rosie the IT expert." We've gone from "I'm not college material," and that person joining a manufacturing firm and earning a living though out a lifetime to raise a family to that option no longer existing. The moribund testing industrial complex is only stressing out teachers and students alike at the K-12 levels, and is not preparing those students for more rigorous collegiate-level work, merely maintaining the inequality status quo 5,6,7. We have an opportunity to construct a future based on alternative energy solutions that could - generate a new level of employment that the nation could educate and prepare a future workforce to fulfill. Such gainful employment would relieve a host of - not ALL - social pressures that are in essence a competition for resources and an artificial, socially inequitable sequester/squandering of the same. We could lead on climate emissions reduction and reduce in-kind, stresses that are currently plaguing our society; that may have built a grievous foundation to the two spectacular attacks in Paris this calendar year, where current climate talks are happening this week. 

What essentially are we going to do with swaths of humanity not prepared for the jobs of the future...or now? Why aren't our elected representatives answering these substantive questions beyond soundbites, sloganeering and talking points or any science-based questions to "inherit the wind" of nuclear codes to possible species extinction?

Perhaps we need to ask them.

1. Smithsonian Institution: What the Luddites Really Fought Against, Richard Conniff

APS News Links
2. Does Science Bear Any Responsibility for Today’s Political Discontent? Michael S. Lubell
3. Underrepresentation of African Americans Persists in Physical Sciences, Emily Conover
4. Women in Physics Statistics
5. Fighting the Gender Gap:Standardized Tests Are Poor Indicators of Ability in Physics
6. Session L5. COM & CSWP: GRE/SAT Predictors of Graduate/Undergradute Performance for Women and Minorities.
7. Abstract: H12.00002 : Allocation of Wealth and Emergence of Inequality

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Wow! I was suprised to see that the BLACK PANTHER will make his debut into the Captain America/Avengers/Marvel Universe in the next CAPTAIN AMERICA: CIVIL WAR movie. Given just these two scenes in the trailer has a person wondering who's side he is on in this movie (if there is a side to be on). ANTHONY MACKEY as The S.H.I.E.L.D. Agent Falcon, DON CHEADLE as War Machine and CHADWICK BOSEMAN as the Panther....

What? NO SAMUEL L. JACKSON? The Quota for BLACK MEN in a movie had been met?? LMAO! JKG Y'all! This should be a good film especially if it is anything like the former two which established that the "A" on Caps forehead had a lil' more meaning than just "AMERICA YO!"

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BLACK FRIDAY... Support the NEGASH™ Lines

Check out the DETROIT based apparel NEGASH™ Lines sporting positive hieroglyphics and contemporay style of owner Rocklin Hotep Negash accessory lines for the family.

I choose this review because it is REAL and BLACK. the reviewer DaJon Pearson gives us his believable opinions has me considering saving my duckets for a pair of shoes. 

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SpaceX Crewed Mission...

SpaceX is modifying Launch Pad 39A at NASA's Kennedy Space Center in Florida to adapt it to the needs of the company's Falcon 9 and Falcon Heavy rockets, which are slated to lift off from the historic pad in the near future. Credit: SpaceX


Topics: International Space Station, NASA, Space Exploration, Spaceflight


It's official: SpaceX will fly NASA astronauts to the International Space Station a few years from now.

California-based SpaceX has secured its first astronaut taxi order under its Commercial Crew Transportation Capability (CCtCap) contract with NASA, agency officials announced Friday (Nov. 20).

"It's really exciting to see SpaceX and Boeing with hardware in flow for their first crew rotation missions," Kathy Lueders, manager of NASA's Commercial Crew Program, said in a statement. "It is important to have at least two healthy and robust capabilities from U.S. companies to deliver crew and critical scientific experiments from American soil to the space station throughout its life span."

Space.com: NASA Orders 1st Crewed Mission from SpaceX, Mike Wall

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Cyborg Roses...

Researchers in Sweden have used roses to create a number of basic electronic devices. (Courtesy: Eliot Gomez/Linköping University)


Topics: Bioengineering, Biology, Electrical Engineering, Photosynthesis


I have to admit: this would have been a better post around Valentine's Day! Enjoy your turkey, pheasant, Cornish hen (in my case) or vegan meal.

Researchers in Sweden have created electronic circuits and devices that are integrated within living plant material. The team introduced a conductive polymer into the vascular system of plants, which allowed the researchers to create the key components of an electrical circuit. They were also able to demonstrate transistor modulation, digital logic function and elements of a digital display. Plant-integrated electronics could enable us to monitor and regulate plant physiology and harvest energy from photosynthesis, the team says.

Organic electronic materials are polymers and molecules that can conduct and process both electronic and ionic signals. They can be shaped into almost any form and used to build devices that can convert electronic signals into chemical processes, and vice versa. The resulting electrochemical devices can then be used to regulate and monitor biological and chemical processes. Such technologies are currently being exploited in various medical settings, such as drug delivery, regenerative medicine, neuronal interconnects, and diagnostics.

Physics World: Cyborg roses become transistors and logic gates, Michael Allen

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Finn! I AM YOUR FATHER!!!!

There's scuttlebutt going around that the character Finn in The Force Awakens, may be Lando Calrissian's son. Check this from ScreenRant:

SuperBroMovies was the first to spot an Amazon listing for a Star Wars: The Force Awakens 1000 piece jigsaw puzzle in a collectible tin. That in itself isn’t the exciting part (unless you really like jigsaw puzzles), but the image on the puzzle is of Finn (John Boyega) and the listing explicitly describes him as Lando Calrissian’s son. Lando, of course, was the former owner of the Millennium Falcon: a suave gambler and smuggler who eventually joined the Rebel Alliance. Calrissian was played by Billy Dee Williams, who has hinted that he may make an appearance in the new slate of Star Wars movies.

I guess we will know for sure in a short while. 

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Finding Field Equations...

Figure 1. Albert Einstein (1879–1955), in this 1916 photograph, poses in his study at Wittelsbacherstraße 13 in Berlin-Wilmersdorf. (Courtesy of the Leo Baeck Institute, New York.)
Citation: Phys. Today 68, 11, 30 (2015); http://dx.doi.org/10.1063/PT.3.2979


Topics: Einstein, History, General Relativity, Research


In his later years, Einstein often claimed that he had obtained the field equations of general relativity by choosing the mathematically most natural candidate. His writings during the period in which he developed general relativity tell a different story.

This month marks the centenary of the Einstein field equations, the capstone on the general theory of relativity and the highlight of Albert Einstein’s scientific career.1 The equations, which relate spacetime curvature to the energy and momentum of matter, made their first appearance in a four-page paper submitted on 25 November 1915 to the Prussian Academy of Sciences in Berlin and reprinted in TheCollected Papers of Albert Einstein (CPAE),2 volume 6, document 21. How did Einstein, shown in figure 1, arrive at those equations? He later insisted that the gravitational equations “could only be found by a purely formal principle (general covariance).”3 Such statements mainly served to justify his strategy in the search for a unified field theory during the second half of his career. As a description of how he found the field equations of general relativity, they are highly misleading.

The 25 November paper was the last in a series of short communications submitted to the Berlin Academy on four consecutive Thursdays that month (CPAE 6; 21, 22, 24, 25). In the first paper, Einstein replaced the field equations that he had published in 1913 with equations that retain their form under a much broader class of coordinate transformations (see figure 2). In the second, a highly speculative hypothesis he adopted about the nature of matter allowed him to change those equations to equations that are generally covariant—that is, retain their form under arbitrary coordinate transformations. In the fourth, he achieved the same end by changing the field equations of the first paper in a different and more convincing way, as shown in figure 3. In the third, based on the field equations of the second paper but unaffected by the modification of the fourth, he accounted for the 43 seconds of arc per century missing in the Newtonian account of the perihelion motion of Mercury.

Physics Today: Arch and scaffold: How Einstein found his field equations
Michel Janssen and Jürgen Renn

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