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Gravitational lensing, also known as an Einstein ring This occurs when the strong gravitational pull of a massive object warps spacetime around it so much that light and other forms of electromagnetic radiation are deflected from a straight path. For example, animations show how a black hole passing in... show more

Black Hole

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36,586 次观看 • 5 个月前 •via X (Twitter)

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Cecilia Chirenti & her team discovered this pair of spinning neutron stars smashing into each other, forming a single massive star, then collapsing into a black hole. The sound is gravitational waves. (from old NASA satellite data)

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When a nuclear reactor is switched on for the first time, an intense, almost hypnotic blue glow appears in the water surrounding the reactor core. This light is neither fire nor heat; it is Cherenkov radiation, a physical phenomenon that occurs when charged particles, such as high-energy electrons produced during nuclear fission, travel through a transparent medium faster than light can propagate within that same medium. While nothing can exceed the speed of light in a vacuum, light travels more slowly in materials like water. When a charged particle surpasses this reduced speed, it emits a coherent shock-like electromagnetic wave, often described as an optical analogue of a sonic boom. This radiation produces the distinctive blue glow. The colour arises because Cherenkov radiation is strongest at shorter wavelengths, which are dominated by blue and ultraviolet light. The phenomenon was first observed experimentally in 1934 and later explained theoretically, work that led to the Nobel Prize in Physics in 1958. Its explanation confirmed how relativity and electromagnetism operate in material media. Today, this deep blue light is both a warning and a scientific tool. It signals the presence of intense ionising radiation, while also being exploited in particle detectors, nuclear reactors, and neutrino observatories. It provides a rare, visible manifestation of subatomic processes that are otherwise hidden from direct human perception. #GottaLovePhysics #Physics

When a nuclear reactor is switched on for the first time, an intense, almost hypnotic blue glow appears in the water surrounding the reactor core. This light is neither fire nor heat; it is Cherenkov radiation, a physical phenomenon that occurs when charged particles, such as high-energy electrons produced during nuclear fission, travel through a transparent medium faster than light can propagate within that same medium. While nothing can exceed the speed of light in a vacuum, light travels more slowly in materials like water. When a charged particle surpasses this reduced speed, it emits a coherent shock-like electromagnetic wave, often described as an optical analogue of a sonic boom. This radiation produces the distinctive blue glow. The colour arises because Cherenkov radiation is strongest at shorter wavelengths, which are dominated by blue and ultraviolet light. The phenomenon was first observed experimentally in 1934 and later explained theoretically, work that led to the Nobel Prize in Physics in 1958. Its explanation confirmed how relativity and electromagnetism operate in material media. Today, this deep blue light is both a warning and a scientific tool. It signals the presence of intense ionising radiation, while also being exploited in particle detectors, nuclear reactors, and neutrino observatories. It provides a rare, visible manifestation of subatomic processes that are otherwise hidden from direct human perception. #GottaLovePhysics #Physics

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It's Black Hole Friday! This computer simulation shows a gas cloud encountering two supermassive black holes. As gravitational and frictional forces meet, the cloud condenses and heats. Each time the black holes orbit, some of the gas is ejected. Learn how scientists use data like this to improve their observations and understanding of cosmic systems:

It's Black Hole Friday! This computer simulation shows a gas cloud encountering two supermassive black holes. As gravitational and frictional forces meet, the cloud condenses and heats. Each time the black holes orbit, some of the gas is ejected. Learn how scientists use data like this to improve their observations and understanding of cosmic systems:

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Surgical lights cast no visible shadow Each light source emits beams from different angles. When an object, such as a hand, blocks one of the beams, the remaining beams continue to light the area, effectively preventing shadows from forming. This design ensures that surgeons have a consistently well-lit view of the operating area.

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How a "Lubor’s lens" works. This is a type of Fresnel lens that takes the light coming into it from the back at obtuse angles and projects it forward in the front of the lens [📹 NightHawkInLight]

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When a spacecraft leaves Earth, it doesn’t just fire its engines and head straight to its destination. In many missions, especially those going beyond low Earth orbit, there’s a more subtle and elegant strategy at play, one that uses gravity itself as part of the navigation system. This is often called a gravity assist, or a slingshot maneuver. But in the case of missions like #Artemis II, what’s being used is a closely related idea known as a free-return trajectory. At first glance, it might sound simple: the spacecraft goes to the Moon, loops around it, and comes back. But the physics behind it is anything but simple. Instead of relying on continuous propulsion, the spacecraft follows a carefully calculated path through the gravitational field of the Earth–Moon system. It is launched with just the right speed and direction so that, as it approaches the Moon, the Moon’s gravity bends its trajectory. The spacecraft is effectively flung around the Moon, redirected onto a path that naturally brings it back toward Earth. No major engine burn is needed for the return. Small trajectory corrections may still be required, but gravity does the heavy lifting. That’s the key. This kind of trajectory is not just efficient, it’s also safe. If something goes wrong with the spacecraft’s engines or onboard systems, gravity itself ensures the return. It’s an inherent backup plan, built into the trajectory from the very beginning. The same fundamental idea appears in gravity assists used across the Solar System. When a spacecraft flies past a planet, it can gain or lose speed by exchanging momentum with that planet. From the spacecraft’s point of view, it’s as if it has been accelerated without using fuel. In reality, it has borrowed a tiny amount of orbital energy from the planet itself. That’s how missions like Voyager reached the outer planets, and how probes continue to explore regions far beyond what their onboard fuel alone would allow. But there’s an important distinction. An interplanetary gravity assist is typically used to change speed and direction, often increasing the spacecraft’s energy. A free-return trajectory, like the one used in Artemis II, is designed for something more specific: a path that naturally loops back to Earth without requiring additional propulsion. It’s less about gaining energy, and more about shaping a trajectory that guarantees a return. To understand why this works, it helps to stop thinking in straight lines. In space, motion follows curves defined by gravity. The spacecraft is constantly falling, first toward Earth, then toward the Moon, and then back toward Earth again. What looks like a loop is really a continuous free fall through a changing gravitational landscape. This way of navigating space reveals something deeper. We tend to think of engines as the drivers of motion, but once a spacecraft is on its way, gravity does most of the work. The art of spaceflight is not just about thrust. It’s about knowing when not to use it. #GoodLuck #Artemis NASA Artemis

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When a nuclear reactor powers on for the first time, the core fills with a deep blue glow that feels almost unreal as it rises through the water in a quiet surge of energy. The light is Cherenkov radiation, created when charged particles move through the water faster than light can travel in that medium, a discovery made in the 1930s that revealed a new way to see high energy reactions. Every appearance of this glow is a reminder of how powerful atomic reactions can be, showing a rare moment where raw physics becomes something visible and strangely beautiful.

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you can play around with it here: (made in 45m on the 7 train!) how it works: each vertical line represents an instrument. a note is played when an object crosses the line, and where it crosses vertically determines pitch. ty Bobby Thakkar Replit ⠕ & team for such a fun day!

you can play around with it here: (made in 45m on the 7 train!) how it works: each vertical line represents an instrument. a note is played when an object crosses the line, and where it crosses vertically determines pitch. ty Bobby Thakkar Replit ⠕ & team for such a fun day!

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It is believed that chanting this stotram three times a day, for six months, fulfils the wishes of devotees. The Yantrodharaka Hanumat Stotram is a hymn in the praise of Lord Hanuman written by Shri Vyasaraja (Vyasatirtha). One day, when sage Vyasaraja was meditating on the banks of River Tungabhadra, he obtained a vision of Lord Hanuman. In order to capture this vision, he etched an image of a monkey on a rock. To his great surprise, the monkey from the illustration came alive. So, he etched an image once again. But, a live monkey materialised from the image once more. So, he repeated this process twelve times. After the twelfth time, he drew a monkey and encased it within a geometric pattern (a yantra) so that it wouldn't incarnate. Hence, the idol came to be known as the 'Yantrodharaka Hanuman' or the 'Hanuman held in the yantra'. Today, one finds a temple around this idol, known as the Yantrodharaka Hanuman Temple, near Hampi.

It is believed that chanting this stotram three times a day, for six months, fulfils the wishes of devotees. The Yantrodharaka Hanumat Stotram is a hymn in the praise of Lord Hanuman written by Shri Vyasaraja (Vyasatirtha). One day, when sage Vyasaraja was meditating on the banks of River Tungabhadra, he obtained a vision of Lord Hanuman. In order to capture this vision, he etched an image of a monkey on a rock. To his great surprise, the monkey from the illustration came alive. So, he etched an image once again. But, a live monkey materialised from the image once more. So, he repeated this process twelve times. After the twelfth time, he drew a monkey and encased it within a geometric pattern (a yantra) so that it wouldn't incarnate. Hence, the idol came to be known as the 'Yantrodharaka Hanuman' or the 'Hanuman held in the yantra'. Today, one finds a temple around this idol, known as the Yantrodharaka Hanuman Temple, near Hampi.

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Mummy of Pacheri : It is the mummy of a man about 1.65m tall, who lived during Ptolemaic Period (305-30 BC). It called 'Mummy of Pacheri', although the reading of the name remains problematic. The quality of its embalming, as well as the state of conservation make it a specimen noticeable and worthy of notice. The mummy is a perfect example for anyone wanting to understand the technique of embalming, and that is probably why it attracts such fascination from visitors. What adds to the charm of this mummy, is also its location in the museum. Indeed, located in a small niche at the back of the large sarcophagi room. At the top of the so-called Osiris crypt, the mummy is only visible in a certain dim light and remains well hidden, isolated from other artifacts, as if rest was a necessity for it in such a busy museum. According to the results of an X-ray analysis, this mummy is that of an adult man. His name, written hastily, can be read as either Pacheri or Nenu; the interpretation is still uncertain. The wide used collar covering his chest is formed of several rows of beads and includes falcon-headed clasps. The apron covering the body features various scenes arranged in registers, notably the mummy lying on a bed, surrounded by the goddesses Isis and Nephtys, and the four sons of Horus. Finally, the casing around the feet has two images of the funerary god Anubis. Louvre Museum (N 2627) 📽️© antiqua_archeologia (IG) - Subscribe for Weekly Newsletter - #archaeohistories

Mummy of Pacheri : It is the mummy of a man about 1.65m tall, who lived during Ptolemaic Period (305-30 BC). It called 'Mummy of Pacheri', although the reading of the name remains problematic. The quality of its embalming, as well as the state of conservation make it a specimen noticeable and worthy of notice. The mummy is a perfect example for anyone wanting to understand the technique of embalming, and that is probably why it attracts such fascination from visitors. What adds to the charm of this mummy, is also its location in the museum. Indeed, located in a small niche at the back of the large sarcophagi room. At the top of the so-called Osiris crypt, the mummy is only visible in a certain dim light and remains well hidden, isolated from other artifacts, as if rest was a necessity for it in such a busy museum. According to the results of an X-ray analysis, this mummy is that of an adult man. His name, written hastily, can be read as either Pacheri or Nenu; the interpretation is still uncertain. The wide used collar covering his chest is formed of several rows of beads and includes falcon-headed clasps. The apron covering the body features various scenes arranged in registers, notably the mummy lying on a bed, surrounded by the goddesses Isis and Nephtys, and the four sons of Horus. Finally, the casing around the feet has two images of the funerary god Anubis. Louvre Museum (N 2627) 📽️© antiqua_archeologia (IG) - Subscribe for Weekly Newsletter - #archaeohistories

Archaeo - Histories

57,028 次观看 • 2 年前

An anvil cloud (scientifically known as Cumulonimbus incus) is the flat, spreading top of a mature thunderstorm cloud. It forms when warm air rises rapidly, hits the stratosphere (a natural ceiling), and spreads horizontally. This is what it looks like from an airliner.

An anvil cloud (scientifically known as Cumulonimbus incus) is the flat, spreading top of a mature thunderstorm cloud. It forms when warm air rises rapidly, hits the stratosphere (a natural ceiling), and spreads horizontally. This is what it looks like from an airliner.

Massimo

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Thousands of people are linking hands around Parliament as a unified call for an immediate ceasefire in Gaza as well as to send a strong message to Keir Starmer's new government to stop arming Israel. This is an amazing act of solidarity in the capital to show that the people stand with Palestine 🇵🇸

Thousands of people are linking hands around Parliament as a unified call for an immediate ceasefire in Gaza as well as to send a strong message to Keir Starmer's new government to stop arming Israel. This is an amazing act of solidarity in the capital to show that the people stand with Palestine 🇵🇸

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Dzhubga Dolmen and Doguab River Dolmen 4, 3rd–2nd millennium BC. These two Western Caucasus dolmens are around 4,000–5,000 years old and show the same Bronze Age building tradition: large stone slabs, massive capstones, and small front openings used for access to the burial chamber. Dzhubga is especially important because research recorded petroglyphs, a stone cairn, a retaining wall, and a circular yard in front of the chamber. Doguab River Dolmen 4 is known for its heavy overhanging capstone and round entrance, often called a “soul hole,” though archaeologists also describe it as a port-hole slab entrance. Same region, same building tradition, two strong examples of Bronze Age monumentality.

Dzhubga Dolmen and Doguab River Dolmen 4, 3rd–2nd millennium BC. These two Western Caucasus dolmens are around 4,000–5,000 years old and show the same Bronze Age building tradition: large stone slabs, massive capstones, and small front openings used for access to the burial chamber. Dzhubga is especially important because research recorded petroglyphs, a stone cairn, a retaining wall, and a circular yard in front of the chamber. Doguab River Dolmen 4 is known for its heavy overhanging capstone and round entrance, often called a “soul hole,” though archaeologists also describe it as a port-hole slab entrance. Same region, same building tradition, two strong examples of Bronze Age monumentality.

History Content

15,521 次观看 • 1 个月前