Blowing in the Wind

"When there is a storm, and you stand in front of a tree—if you look at its branches, you swear it will fall. But if you look at the trunk, you will see its stability."

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The Truth About Gravitational Waves

For the first time ever, gravitational waves have been detected directly, and the news — broken by the LIGO team on February 11, 2016 — has made some waves of its own. To sort out some difficult-to-explain points that have made their way into the media this week, we turn to the experts: Lynn Cominsky, Professor and Chair of the Physics Department at Sonoma State University, who joined Physics Central recently for a live Q&A following the announcement, and Rana Adhikari, Professor of Physics at Caltech.

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Scientists Propose "Death Star" Laser Defense Against Asteroids

Lasers mounted on robot spacecraft or giant satellites could deflect asteroids away from Earth, suggest new orbital simulations exploring this defense strategy.

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A New Ninth Planet?

For most of human history, our solar system had 6 planets (counting the Earth), the ones that could be observed by eye, wandering across the night sky. In 1781, William Herschel’s telescope revealed a seventh — Uranus — but it was the eighth planet that became the great triumph of nineteenth century Newtonian celestial mechanics. In the 1840s, unexplained perturbations in the orbit of Uranus led French mathematical astronomer Urbain Jean Joseph Le Verrier and English astronomer John Couch Adams to independently predict the existence and approximate orbit of a distant as-yet-unseen planet. Armed with his calculations, Le Verrier convinced two German astronomers to look for his planet, they almost immediately found it, right where it was predicted to have been.

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LIGO: What You Need to Know

For weeks now, rumors of big news in physics have swirled through the scientific (and science-enthusiastic) community. As it turns out, the rumors are true—LIGO and Virgo, the worldwide scientific collaborations dedicated to directly detecting gravitational waves, have just announced this morning that they've observed the signal that scientists have been looking for since Einstein's theory of general relativity was postulated a full century ago! While it's still going on, you can watch a live stream of the announcement here! To help you understand what the discovery means and how it could shape the future of physics, we've put together this page as a sort of "one-stop shop" for physics enthusiasts and aspiring physicists alike.


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Not Just Waves but Black Holes (Go LIGO!!)

UPDATE: TUNE IN AT 3PM TODAY TO ASK A LIGO SCIENTIST ALL YOUR QUESTIONS

“This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.” This final line of a paper published this morning in Physical Review Letters by the Laser Interferometer Gravitaional-Wave Observatory (LIGO) collaboration sums up today’s press conference announcement. 14 years after their search began and 100 years after Einstein predicted them, gravitational waves were detected. This would be headline news on its own, but LIGO got in a second first, highlighting the “observatory” part of their name:  they are the first to observe a black hole merger. And just to add another interesting twist, no one really thought we’d find black holes this size (they are the largest stellar black holes every observed). Let’s hope they have one heck of a bottle of champagne in Hanford, WA and Livingston, LA today.  

Two black holes are entwined in a gravitational tango in this artist's conception. Supermassive black holes at the hearts of galaxies are thought to form through the merging of smaller, yet still massive black holes, such as the ones depicted here. Image credit: NASA

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LIGO Live! Q&A With Lynn Cominsky

Lynn Cominsky, physicist with the LIGO collaboration, will be answering your questions about LIGO's Feb. 11 announcement live. Tweet questions to @physicscentral #LIGOlive or comment here.

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Ask a Physicist: Protons & the Strong Force

Oscar, from New Mexico, wants to know:
"Electromagnetic repulsion is inversely related to the square of the distance between both objects. Shouldn't this mean that the integral of the force between two protons is infinite if the distance becomes zero? If so, why can protons collide?"

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Big Data, Quantum Solutions

Modern computers, like the one you're probably reading this on, are capable of performing the kind of calculations that, in the early days of computing, it would have taken a room-filling apparatus to do. Supercomputers, the modern incarnation of those room-fillers, can execute something close to a thousand trillion operations per second, crunching through incomprehensibly large amounts of information with relative ease. Unfortunately, even the mightiest of these modern analytical engines are cowed by the prospect of tackling the latest player to emerge onto the scene: big data.

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Ask a Physicist: The Shapiro Delay

Adhersh from India, wants to know:
What will be the behavior of light when it passes between two highly massive bodies?

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