Tag: light

Scientists Have Found A Way To Slow Light To A Complete Stop

Scientists have proposed a theoretical way that light could be slowed down to a complete stop, using something called “exceptional points”.

Published in Physical Review Letters, the authors describe in their study how previous methods included using a cloud of ultracold atoms of sodium to slow light down to speeds approaching zero, but not quite there.

Their method, however, involves using a waveguide – a structure that guides waves in other words, like a tube – to create exceptional points. These are regions where two complex wavelength patterns meet and merge.

What does that mean exactly? Well, we know that light is a wave (most of the time), and these waves constantly change their shape depending on what they’re moving through.

As Live Science notes, if you tune the properties of a container, you can collapse one of light’s complex waves with its mirror twin. Essentially, they cancel each other out. And the point at which that happens is called an exceptional point.

“In this work, we disclose the relation of the stopped light effect with the phenomenon of [the] exceptional point,” the researchers, Tamar Goldzak and Nimrod Moiseyev from the Israel Institute of Technology and Alexei Mailybaev from the Institute for Pure and Applied Mathematics in Brazil, wrote in their paper.

Exceptional points have been shown to have some weird physics before, such as causing lasers to switch on despite energy seemingly being taken away. Sending two wave modes past an exceptional point was described as “driving a car into an icy two-lane tunnel, in which one slides around wildly, but from which one always comes out on the correct side of the road.”

According to this latest paper, in theory, you can cause beams of light to stop moving completely at an exceptional point by changing their properties. The light can then move again when the properties are reversed.

This research is, right now, theoretical. But it could open some interesting avenues for so-called “slow-light applications”, useful for things like telecommunications. And the researchers said the method could apply not just to light waves, but other waves like sound too.


Read more: http://www.iflscience.com/physics/scientists-have-found-a-way-to-slow-light-to-a-complete-stop/

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Read This Inspiring “Letter To My Past Self” From A Student Who Escaped Afghanistan To Study Science

The right to an education is article 26 of the Universal Declaration of Human Rights. Sadly, like all the other articles, this is often ignored, particularly for women.

In some countries, girls are not only denied an education but are threatened if they try to obtain one. Last year IFLScience heard the story of Lema, an Afghan girl who stopped going to school after her life was threatened, but taught herself to read English at home from a newspaper. From the age of 13 Lema used the power of the Internet to access online education systems from home, and she fell in love with physics and mathematics, spending years developing her knowledge of these fields as well as could be done remotely.

Afghanistan doesn’t have a SAT testing site, so the only way Lema could win entry to American universities was to be smuggled into Pakistan. The trip was so hazardous family members tried to get her to give up on her dream of studying abroad, but an uncle agreed to take her on a trip he was making for other reasons. The journey was so long that when she arrived the site was full, but SAT management decided if ever there was a time to bend the rules this was it, and allowed her to sit the test.

Despite her lack of formal education, Lema did well enough that she was offered a place at several American universities. Unfortunately, her initial attempts to get a visa to study in America were rejected.

We first heard about Lema’s story through a lobbying campaign to get her visa approved, combined with fundraising to pay for travel and tuition. We wanted to get behind this campaign. However, publicity about her story also attracted the attention of enemies of girls’ education, and there were fears of reprisals against her family. Additional media was thought likely to increase the danger, so naturally, we didn’t run anything.

Now, a year later, we are delighted to learn Lema has made it to a university in America, and is loving it, although we still can’t use her real name as fears of reprisals to her family are still ongoing. She has even been granted a full scholarship, so is no longer seeking financial support. On the other hand, she does want to inspire other girls to know what is possible, and sent us the letter to her former self, published on the next page, in the hope it can reach others who are told maths and physics are not for them.

As you can imagine, we are deeply honored that she chose IFLScience to get her message to the world, and to learn she loves reading us.

A Letter to My Past Self

To the girl who is just beginning to dream about the stars and galaxies in a corner of the world where dreaming is forbidden to her. To the girl who does not know yet what her existence means to her and everyone else. To the girl who wants to run, who wants to fly, who even wants to fall, but never wants to stop. You will get your wings.

I know its hard to imagine a life of self-esteem and respect now, but I want you to know it is possible. They will ruffle your feathers, try to get you to stop learning, but you will learn how to ignore it. I know you hear now, Your Xs and Ys wont help you if you mother-in-law asks you to cook. Your wings are clipped by your three-year-old nephew, so arrogant of his gender that even at that age he asks, Why are you studying? You are a girl! It hurts, I know, and you might not have the answer today, but you will. Someday soon youll answer that little guys big question: I am studying math and science to temporarily liberate myself from a life of bigotry and difficulty from a life reduced to just cooking and assimilating into a society where I am told womans place is in the house or in the grave. I am studying to travel the world and read about enlightenment.

You give off incredible light in a part of the world still enshrouded in darkness, where people fear becoming blind by the brightness of the light. You will be warned, too. Keep challenging their lies. Stare them in the eyes and show them that your brain has more than enough capacity to understand infinities and integrals and think about the universe. Every equation you learn will take you one step closer to understanding a universe full of wonder, to finding your own meaning. I have to tell life will reward your struggle, even if you dont see it now. I know you dont expect anything in return in the pursuit of learning other than a temporary mental freedom, but you will be emboldened by strangers who appreciate the struggle of your flight. You will make friends and share ideas. You will leave the nest, flying to heights you never imagined possible.

To my younger self, keep growing the effort is worth it. In the words of Ovid, Be patient and tough; someday this pain will be useful to you.

Read more: http://www.iflscience.com/physics/read-this-inspiring-letter-to-my-past-self-from-a-student-who-escaped-afghanistan-to-study-science/

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This Light Painting, Double Pendulum Elegantly Demonstrates Chaotic Movement

Pendulus” is a double pendulum built by Devin Montes that visualizes the unpredictable patterns of chaotic movement in real-time, using an LED light and glow-in-the-dark paint.

For more cool projects, check out Devin’s YouTube channel, Make Anything // 3D Printing Channel

Read more: http://twistedsifter.com/videos/light-painting-double-pendulum-visualizes-chaotic-movement/

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