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Showing results 81-91 of 105 for 'Physics'

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    Jerusalem Tower Younger than Thought

    Gihon Spring, just downhill from the ancient city of Jerusalem, was crucial to the survival of its inhabitants, and archaeologists had uncovered the remains of a massive stone tower built to guard this vital water supply. Based on pottery and other regional findings, the archaeologists had originally assigned it a date of 1,700 BCE. But new research conducted at the Weizmann Institute of Science provides conclusive evidence that the stones at the base of the tower were laid nearly 1,000 years later.

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    A Possible Explanation for Why No Intermediate Sized Black Holes Have Been Found

    A pair of researchers, one with the Weizmann Institute of Science in Israel the other with Princeton University in the U.S. has come up with a possible explanation for the inability of space scientists to find any intermediate-sized black holes. In their paper published in the journal Nature Astronomy, Tal Alexander and Ben Bar-Or offer an outline of current theories regarding how black holes in general are believed to develop, theories about the early universe, and finally, their ideas on how current theories may lead to an explanation for the dearth of intermediate sized black holes.

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    Carbon Dating Undermines Biblical Narrative for Ancient Jerusalem Tower

    A new Weizmann Institute study has discovered radiocarbon-dating evidence of the First Temple period under a tower in Jerusalem’s City of David that was previously dated to the Canaanite period. The findings, based on soil samples taken from under a seven-meter thick walled tower, shave nearly a thousand years from previous archaeological dating of the structure, which placed it c. 1700 BCE — and contradict a presumed biblical linkage to the site. Downhill from the Temple Mount of Jerusalem, the Gihon Spring guard tower was discovered in 2004 by archaeologists Ronny Reich and Eli Shukron. Based on pottery and architectural signifiers, the heavily fortified structure — and the rest of the Spring Citadel protecting Jerusalem’s precious water source — were dated to Canaanite construction (Middle Bronze II period).

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    Lucky Break Leads to Controversial Supernova Discovery

    It was not a slow death — it lasted a few hours at most. The casualty was a star in a spiral galaxy some 160 million light-years away. Its core collapsed in on itself, triggering a supernova explosion as bright as 100 billion suns. On a cosmic scale, this star was rather ordinary, probably a red supergiant some 10 times more massive than our sun. But on October 6, 2013, when the light from the explosion finally reached Earth, its death made history. The glow from SN 2013fs, as it’s now called, hit the right robotic witness, and then astronomers caught a cosmically lucky break.

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    Recipe Unearthed for Mystery Clouds

    The weather forecast had predicted a cloudless day, but when Ilan Koren, an atmospheric scientist, looked up he saw small “cotton wool” clouds dotted across the bright blue sky over Israel. “Mystery” clouds like these are common on hot sunny days along humid sub-tropical shores, like those along the Mediterranean. Yet classical physics suggests these clouds shouldn’t exist. Now scientists think they might have finally solved the puzzle of how mystery clouds are made.

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    The Breaking Point

    It is said that a weak link determines the strength of the entire chain. Likewise, defects or small cracks in a solid material may ultimately determine the strength of that material – how well it will withstand various forces. For example, if force is exerted on a material containing a crack, large internal stresses will concentrate on a small region near the crack’s edge. When this happens, a failure process is initiated, and the material might begin to fail around the edge of the crack, which could then propagate, leading to the ultimate failure of the material.

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    New Technique Improves Properties of Superconductors

    Weizmann Institute of Science and Hebrew University researchers have made the first direct visual observation and measurement of ultra-fast vortex dynamics in superconductors. They say their technique, detailed in the journal Nature Communications, could contribute to the development of novel practical applications by optimizing superconductor properties for use in electronics. Superconductivity is a state of matter in which an electric current can flow with absolutely no resistance. This occurs when certain materials are cooled below a critical temperature. The effect is useful for various applications, from magnetically levitating trains to MRI machines and particle accelerators. It also sparks the imagination with thoughts of lossless power transfer and much faster computation.

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    Colder and Colder

    When investigating atoms, scientists face a challenge: at room temperature, individual atoms in a gas have kinetic energy, and fly around at high velocities. Temperature is, in essence, the relative movement between atoms; thus, the goal of getting the atoms to have small relative velocities involves freezing them to extremely cold temperatures. Now, a group at the Weizmann Institute of Science has developed a new universal method for cooling ions.

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    Atoms Feel New Force

    <em>Physics</em> reports that Noam Matzliah, a PhD student in the Weizmann Institute’s Department of Physics of Complex Systems, has “demonstrated a new kind of atom-acting optical force that squeezes a whole cloud of atoms.”

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    Jupiter’s Stormy Winds Churn Deep into the Planet

    <em>Nature</em> reports on the international mission to study Jupiter via NASA’s Juno spacecraft. Juno has now “plumbed the depths of Jupiter,” showing that the “planet’s famous bands of swirling winds” extend quite far down. According to Weizmann’s Dr. Yohai Kaspi, “Determining this is one of the main goals of the Juno mission.”