(Roughly) Daily

Posts Tagged ‘gravitational waves

“Magnetism, you recall from physics class, is a powerful force that causes certain items to be attracted to refrigerators”*…


Concentric incision on a jar handle from Ramat Rahel, in modern-day Israel

Of all the environmental amenities that this hospitable planet provides, the magnetic field is perhaps the strangest and least appreciated. It has existed for more than three and a half billion years but fluctuates daily. It emanates from Earth’s deep interior but extends far out into space. It is intangible and mostly invisible—except when it lights up in ostentatious greens and reds during the auroras—but essential to life. The magnetic field is our protective bubble; it deflects not only the rapacious solar wind, which could otherwise strip away Earth’s atmosphere over time, but also cosmic rays, which dart in from deep space with enough energy to damage living cells. Although sailors have navigated by the magnetic field for a millennium and scientists have monitored it since the eighteen-thirties, it remains a mysterious beast. Albert Einstein himself said that understanding its origin and persistence was one of the great unsolved problems in physics…

Direct measurements of the magnetic field now span almost two hundred years, and iron-rich volcanic rocks on the ocean floor provide a lower-fidelity chronicle of its erratic behavior—including wholesale reversals in polarity—back about a hundred and fifty million years. But reconstructing the field’s behavior between these two extremes has been difficult. The trick is to find an iron-bearing object that locked in a record of the magnetic field at a well-constrained time in the past, in the way that wine of a given vintage preserves an indirect record of that year’s weather conditions…

Last Monday, in a study published in Proceedings of the National Academy of Sciences, a team of Israeli and American archeologists and geophysicists reports the most detailed reconstruction yet of the magnetic field in pre-instrumental times, using a set of ceramic jars from Iron Age Judea…

In the geophysical community, the tales told by the Judean jars may cause unrest. Both the height and the sharpness of the spike they recount push up against the limits of what some geophysicists think Earth’s outer core is capable of doing. If the eighth-century-B.C. geomagnetic jeté is real, models for the generation of the magnetic field need significant revision. Given the importance of a stable magnetic field to our electricity-dependent, communications-obsessed culture, these questions are of more than academic interest…

More on these befuddling fields at “Earth’s mysterious magnetic field, stored in a jar.”

* Dave Barry


As we look for True North, we might send undulating birthday greetings to George Fitzgerald Smoot III; he was born on this date in 1945.  An astrophysicist and cosmologist, Smoot discovered the signature of gravitational waves– ripples in space-time were first predicted by Albert Einstein– in his study of the cosmic microwave (“background”) radiation that originated with the Big Bang.  He won the Nobel Prize in Physics in 2006; three years later he became the second person to run the board on the quiz show Are You Smarter than a 5th Grader?, and took home the $1 million grand prize.



“I used to think information was destroyed in black holes. This was my biggest blunder, or at least my biggest blunder in science”*…


email readers click here for video

Gravitational waves sent out from a pair of colliding black holes have been converted to sound waves, as heard in this animation. On September 14, 2015, LIGO [the Laser Interferometer Gravitational-wave Observatory] observed gravitational waves from the merger of two black holes, each about 30 times the mass of our sun. The incredibly powerful event, which released 50 times more energy than all the stars in the observable universe, lasted only fractions of a second.

In the first two runs of the animation, the sound-wave frequencies exactly match the frequencies of the gravitational waves. The second two runs of the animation play the sounds again at higher frequencies that better fit the human hearing range. The animation ends by playing the original frequencies again twice.

As the black holes spiral closer and closer in together, the frequency of the gravitational waves increases. Scientists call these sounds “chirps,” because some events that generate gravitation waves would sound like a bird’s chirp.

More background from LIGO:

email readers click here for video

* Stephen Hawking


As we scan the event horizon, we might send difficult-to-detect birthday greetings to Lawrence Maxwell Krauss; he was born on this date in 1954.  A theoretical physicist and cosmologist, Dr. Krauss was among the first to propose the existence of the enigmatic dark energy that makes up most of the mass and energy in the universe.  He directs the Origins Project, and has written several books on science for the general public, including Fear of Physics (1993), The Physics of Star Trek (1995), Quantum Man: Richard Feynman’s Life in Science (2011), and A Universe from Nothing (2012).



Written by LW

May 27, 2016 at 1:01 am

“Gravity is a habit that is hard to shake off”*…


 click here for zoomable version

Last week, scientists at The Laser Interferometer Gravitational-Wave Observatory, or LIGO, announced that they had confirmed Einstein’s century-old theoretical prediction of “gravitational waves,” a feature of his theory of general relativity.

Our friends at PhD Comics explain why that matters:

email readers click here for video

* Terry Pratchett


As we go with the flow, we might send carefully-calculated birthday greetings to Einstein’s rough contemporary Alfred North Whitehead; he was born on this date in 1861.  Whitehead began his career as a mathematician and logician, perhaps most famously co-authoring (with his former student, Bertrand Russell), the three-volume Principia Mathematica (1910–13), one of the twentieth century’s most important works in mathematical logic.

But in the late teens and early 20s, Whitehead shifted his focus to philosophy, the central result of which was a new field called process philosophy, which has found application in a wide variety of disciplines (e.g., ecology, theology, education, physics, biology, economics, and psychology).

“There is urgency in coming to see the world as a web of interrelated processes of which we are integral parts, so that all of our choices and actions have consequences for the world around us.”


Written by LW

February 15, 2016 at 1:01 am

%d bloggers like this: