Earthquake measurements : Satellites reveal how the disastrous Moroccan earthquake moved the Earth

Satellites revealed the extent of ground movement resulting from the 6.8-magnitude earthquake that struck Morocco last week, killing thousands.

The earthquake struck a rural area in the Atlas Mountains, about 75 km (47 miles) from the city of Marrakesh, on the evening of Friday, September 8. This region is located, according to the European Space Agency (ESA) , on the dividing line between the European and African tectonic plates, which makes the region vulnerable to earthquakes.

Radar measurements conducted by two European satellites within the Sentinel-1 satellite constellation before and after the disaster reveal the extent to which the two plates shifted during the earthquake.

According to the BBC, the upward movement of the surface reached a maximum of 15 cm, while in other areas the ground sank by up to 10 cm.

The European Space Agency said in a statement that images obtained from satellite measurements help scientists and rescue teams assess the situation and the risks of subsequent tremors.

“Earth-orbiting satellites are unique in their ability to not only provide a broad view of affected areas, but also provide very detailed information,” Simonetta Celli, ESA’s director of Earth observation programs, explained in the statement. “They can see through "Clouds are also often used to map dangerous floods. In the case of the Morocco earthquake, the value of the mission was to measure how the surface changed, which will be important once the immediate crisis is over and the restoration process begins."

The two images used to create the visual image, called an interferogram, which captures surface displacement, were taken on August 30, more than a week before the quake, and on September 11, three days after the disaster.

 

Huangzhou Marine : The Chinese are testing a "generator" for the electrical station operating with sea thermal energy

Chinese scientists from the Huangzhou Marine Geological Corporation have successfully tested a device that generates electrical energy with the help of heat reserves that lie deep in the sea.

The Chinese newspaper "China Daily" said: The experiment, which was conducted in real sea conditions, confirmed the generator's ability to extract thermal energy from the sea, as well as its great ability to work.

The newspaper quoted the authority's chief engineer, Nin Po, as saying: "The experiment has become an important step towards expanding the research program in this field, and using the experience and knowledge obtained to conduct land and sea tests in the future." The newspaper also added that China is rich in ocean thermal energy. But previous tests remained at the level of laboratory experiments.

The newspaper indicated that the experiment was conducted under the supervision of the Geological Survey of the People's Republic of China in the waters of the South China Sea. During the experiment, the generator was able to generate electrical power within 4 hours and 47 minutes, reaching a maximum power of 16.4 kilowatts.

 The generator, designed by Chinese specialists, is characterized by the fact that it uses the temperature difference between layers of ocean water located at different distances from the surface, thus turning the ocean into another source of renewable energy.

It is noteworthy that an international team of climate scientists reached the conclusion last January that the amount of heat stored in the upper layers of the world’s oceans had risen to a record level of 255 zettajoules, which is 10.9 zettajoules more than it was in 2020.

 

Physics : Have we misread a key law of physics over the past 300 years?

When Isaac Newton wrote his famous laws of motion in 1687, he probably only hoped we would be discussing them three centuries later.

Newton identified three universal principles that describe how to control the movement of objects in our world, through writing in Latin, which was translated, copied, and discussed at length.

But, according to a philosopher of language and mathematics, we may have been interpreting Newton's precise formulation of his first law of motion a little wrong all along.

After discovering what he described as a “clumsy mistranslation” in the original English translation of Newton’s Principia Latina in 1729, Daniel Hooke, a philosopher at Virginia Tech, wanted to “set the record straight.”

Based on the aforementioned translation, countless academics have since interpreted Newton's first law of inertia to mean that a body will continue to move in a straight line or will remain at rest unless an external force intervenes. It's a description that works well until you realize that external forces are constantly at work, something Newton (of course) took into account in his formulation.

Revisiting the archives, Hooke realized that this common paraphrase contained a misinterpretation that persisted until 1999, when two scholars discovered the translation of one overlooked Latin word: quatenus, which means “to some extent,” and nothing more.

This makes a big difference, according to Hooke. Instead of describing how an object maintains its momentum if no forces act on it, Hooke says the new reading shows that Newton meant that every change in an object's momentum — every jolt, dip, twist, and boom — is due to external forces. .

“By bringing this [somewhat] forgotten word back to its place, these scientists have restored one of the fundamental principles of physics to its original splendor,” Hooke wrote in a blog post about his paper.

However, this critical correction never caught on.

“Some find my reading too wild and unorthodox to be taken seriously,” says Hook. “Others think it is so obviously true that it is hardly worth arguing about.”

Laypeople might agree that this sounds like semantics. Hooke admits that reinterpretation has not and will not change physics. But a closer examination of Newton's own writings makes clear what the leading mathematician of the time was thinking.

Hooke explains that if we take the prevailing translation, which is that bodies move in straight lines until a force forces them otherwise, this raises the question: Why would Newton write a law about bodies devoid of external forces when there is no such thing in our universe? When gravity and friction are always present?

“The main purpose of the first law is to deduce the existence of force,” says George Smith, a philosopher at Tufts University and an expert on Newton’s writings.

In fact, Newton gave three concrete examples to illustrate his first law of motion: the most obvious, according to Hooke, is a rotating top, slowing down in a taut spiral due to air friction.

“By giving this example,” Hooke wrote, “Newton clearly shows us how the first law, as he understands it, applies to accelerating bodies subject to forces, that is, to bodies in the real world.”

Hooke says this revised interpretation restores one of Newton's most fundamental ideas, which was quite revolutionary at the time: planets, stars and other celestial bodies are subject to the same laws of physics as objects on Earth.

The research paper was published in Philosophy of Science .