Thursday, January 19, 2017

9 Things You May Not Know About Albert Einstein-physicsknow


Monday, January 16, 2017

Water, Water Everywhere-physicsknow

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The palm tree-fringed beaches of the Maldives give the appearance of an island paradise. But behind the tiny island nation lies a more complicated story.

The archipelago numbers 1,190 coral islands grouped into 26 atolls. Tourism powers the country’s economy, as 80 of its islands contain resorts. But its most lucrative asset—proximity to the azure seas—threatens to bring its downfall. The Maldives stands to lose much to sea-level rise, according to the United Nations.

As the smallest Asian country, the Republic of Maldives has a total population the size of a modest European city. The islands rise just a smidgeon above the Indian Ocean: roughly 80 percent of the country stands no more than 1 meter (3 feet) above sea level, according to the CIA World Factbook.

The nation was one of the first to warn of the effects of climate change that are already taking place. In 2009, then-president Mohamed Nasheed made international headlines by holding an underwater cabinet meeting in scuba attire to draw attention to the issue.

During bad storms, knee-deep water has inundated some islands. Malé, the capital and home to one-third of the nation’s residents—as well as multi-million dollar concrete stormwalls—has borne the brunt of several large storms in the past few decades. The city has also struggled to contain vector-borne diseases like dengue fever. (Heavy rains leave behind shallow pools where disease-spreading mosquitoes lay their eggs.)

This image was acquired on April 3, 2013, by the Advanced Spaceborne Emission and Reflection Radiometer (ASTER) aboard the Terra satellite. Note: the synthetic natural color image, which combines several different spectral ranges to simulate the look of natural color, makes the islands appear slightly brighter than would an aerial photograph.

Martin Luther King Jr.-physicsknow

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Martin Luther King Jr.
Born on January 15, 1929

Martin Luther King Jr. was a Baptist minister and social activist, who led the Civil Rights Movement in the United States from the mid-1950s until his death by assassination in 1968.
Martin Luther King Jr. was born on January 15, 1929, in Atlanta, Georgia. King, both a Baptist minister and civil-rights activist, had a seismic impact on race relations in the United States, beginning in the mid-1950s. Among many efforts, King headed the SCLC. Through his activism, he played a pivotal role in ending the legal segregation of African-American citizens in the South and other areas of the nation, as well as the creation of the Civil Rights Act of 1964 and the Voting Rights Act of 1965. King received the Nobel Peace Prize in 1964, among several other honors. King was assassinated in April 1968, and continues to be remembered as one of the most lauded African-American leaders in history, often referenced by his 1963 speech, "I Have a Dream."

 

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Sunday, January 15, 2017

science of the week -Illuminating biology-physicsknow

Illuminating biology
Martin Chalfie, heard about the green fluorescent protein for the first time in 1988 at a seminar. During the seminar, Chalfie realised that green fluorescent protein would be a fantastic tool for mapping the roundworm C. elegans. It would act as a glowing green signal for various activities in the roundworm’s cells.
Chalfie succeeded in introducing the gene for GFP into the DNA of the small, almost transparent worm C. elegans. GFP was produced by the cells, giving off its green glow without the need for the addition of any extra components, and without any indication of causing damage to the worms. Subsequent work showed that it was possible to fuse the gene for GFP to genes for other proteins, opening-up a world of possibilities for tracking the localization of specific proteins in living organisms.
The strong green colour of this protein appears under blue and ultraviolet light. It can, for example, illuminate growing cancer tumours; show the development of Alzheimer’s disease in the brain or the growth of pathogenic bacteria.
Warm congratulations to Martin Chalfie, today 70!
Photo: Crystal jelly (Aequorea victoria) taken in the Monterey Bay Aquarium, CA, USA. Author Mnolf,

The Day We Discovered the Universe- physicsknow

Andromeda nebula, photographed at the Yerkes Observatory circa 1900. To modern eyes, this is clearly a galaxy. At the time, though, it was described as "a mass of glowing gas." (From the book Astronomy of To-Day)
What’s in a date? Strictly speaking, New Year’s Day is just an arbitrary flip of the calendar, but it can also be a cathartic time of reflection and renewal. So it is with one of the most extraordinary dates in the history of science, January 1, 1925. You could describe it as a day when nothing remarkable happened, just the routine reading of a paper at a scientific conference. Or you could recognize it as the birthday of modern cosmology–the moment when humankind discovered the universe as it truly is.
Until then, astronomers had a myopic and blinkered view of reality. As happens so often to even the most brilliant minds, they could see great things but they could not comprehend what they were looking at. The crucial piece of evidence was staring them right in the face. All across the sky, observers had documented intriguing spiral nebulae, swirls of light that resembled ghostly pinwheels in space. The most famous one, the Andromeda nebula, was so prominent that it was easily visible to the naked eye on a dark night. The significance of those ubiquitous objects was a mystery, however.

Some researchers speculated that the spiral nebulae were huge and distant systems of stars, “island universes” comparable to our Milky Way galaxy. But many others were equally convinced that the spirals were small, nearby clouds of gas. In this view, other galaxies–if they existed–were far out of sight, blue whales lurking in the far depths of the cosmos. Or perhaps there were no other galaxies at all, and our Milky Way was all there was: a single system that defined the entire universe. The dispute between the two sides was so intense that it prompted a famous 1920 Great Debate…which ended with an unsatisfying draw.
The correct picture of our place in the universe arrived just a few years later through the work of one of the most famous names in astronomy: Edwin Powell Hubble (no relation!). Starting in 1919, Hubble had established himself as one of the most patient and meticulous observers at Mount Wilson Observatory in California.  Mt Wilson, in turn, had just established itself as the premier outpost for astronomical research, home of the just-completed 100-inch Hooker Telescope—then the biggest in the world. It was the perfect combination of the right observer in the right place at the right time.
Always cautious when it came to theory and interpretation, Hubble focused his scientific attention on the spiral nebulae without overtly endorsing the “island universe” interpretation. He preferred to wait until he could be the one to step forward with definitive proof–or disproof, if that’s where the evidence pointed.
In 1922, another important piece of the puzzle fell into place. That year, Swedish astronomer Knut Lundmark observed what he believed were individual stars in the arms of the spiral nebula M33. Shortly after, John Duncan at Mount Wilson spotted dots of light that grew fainter and brighter in the same nebula. Could these be variable stars, similar to ones in the Milky Way but far dimmer owing to their enormous distance?
Sensing the answer was at hand, Hubble stepped up his efforts. He spent long nights on his favorite bentwood chair, guiding the movements of the riveted-steel mount of the Hooker telescope to cancel out Earth’s rotation. The effort paid off with highly detailed, long-exposure images of the Andromeda nebula. The mottled light of the nebula began to resolve itself into a multitude of luminous points, looking not like a smear of gas but like a vast hive of stars.
Clinching proof came in October of 1923, when Hubble spied the telltale flicker of a lone Cepheid variable star in one of Andromeda’s arms. This type of star grows brighter and dimmer in a regular and predictable way, with its intrinsic luminosity directly related to its period of variation. Simply by timing the 31-day cycle of this star as it slowly flickered, Hubble could deduce its distance. His estimate was 930,000 light years–less than half the modern estimate, but a shockingly large number at the time. That distance placed Andromeda, one of the brightest and presumably closest of the spiral nebulae, vastly outside the bounds of the Milky Way.
In principle, the Great Debate was settled then and there. Spiral nebulae were other galaxies, and our Milky Way was just one outpost within a staggeringly vast universe. And yet, still the story was far from over.
Edwin Hubble at the controls of the 100-inch telescope at Mount Wilson, circa 1922. (Credit: Huntington Library)