Science Friday: Gravitational Waves Detected 100 Years After Einstein’s Prediction | Meet the NASA Scientist Who Tracks Dangerous Asteroids in Earth’s Orbit | Gut microbes help prep brown bears for hibernation

The video is an explanation of gravity and a ripple of a gravity wave

For the first time, scientists have observed ripples in the fabric of spacetime called gravitational waves, arriving at the earth from a cataclysmic event in the distant universe. This confirms a major prediction of Albert Einstein’s 1915 general theory of relativity and opens an unprecedented new window onto the cosmos.

Gravitational waves carry information about their dramatic origins and about the nature of gravity that cannot otherwise be obtained. Physicists have concluded that the detected gravitational waves were produced during the final fraction of a second of the merger of two black holes to produce a single, more massive spinning black hole. This collision of two black holes had been predicted but never observed.


Based on the observed signals, LIGO scientists estimate that the black holes for this event were about 29 and 36 times the mass of the sun, and the event took place 1.3 billion years ago. About 3 times the mass of the sun was converted into gravitational waves in a fraction of a second—with a peak power output about 50 times that of the whole visible universe. By looking at the time of arrival of the signals—the detector in Livingston recorded the event 7 milliseconds before the detector in Hanford—scientists can say that the source was located in the Southern Hemisphere.

According to general relativity, a pair of black holes orbiting around each other lose energy through the emission of gravitational waves, causing them to gradually approach each other over billions of years, and then much more quickly in the final minutes. During the final fraction of a second, the two black holes collide into each other at nearly one-half the speed of light and form a single more massive black hole, converting a portion of the combined black holes’ mass to energy, according to Einstein’s formula E=mc2. This energy is emitted as a final strong burst of gravitational waves. It is these gravitational waves that LIGO has observed.



Nasa’s front line defense against killer rocks from space

THE SOLAR SYSTEM Dynamics group of NASA’s Jet Propulsion Lab is, as physicist Marina Brozovic explains, is like “flight control for the solar system.” Basically, it’s the best line of defense between you and the flaming chunks of space rock hurtling toward Earth pretty much all the time. Even though major collisions might seem like something that only affects the distant past or remote areas—a headache for T-Rexes and Russians, but not you—the fact that more population centers haven’t been in harm’s way so far is basically down to random chance.

The reality is that there are millions of near-earth objects swirling out there right now, and we don’t even know where most of them are. …



Gut microbes help prep brown bears for hibernation

Researchers are spending a lot of time exploring how the microbes living in our guts impact our health. In a new study published in Cell Reports, researchers wanted to know how the gut microbes of wild brown bears changes between summer and hibernation. They discovered that during the summer, the microbial species present in the gut are more diverse and are of the type that helps store energy. In fact, when the research team gave the microbes to rodents, the rodents gained weight. This seasonal variation in the species of microbes may be what helps prevent bears from developing diabetes or other disorders as they gain weight.



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