Reference Terms
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Mass
Mass is a property of a physical object that quantifies the amount of matter it contains. Unlike weight, the mass of something stays the same regardless of location. Mass is a central concept of classical mechanics and related subjects, and there are several forms of mass within the framework of relativistic kinematics. In the theory of relativity, the quantity invariant mass, which in concept is close to the classical idea of mass, does not vary between single observers in different reference frames. In classical mechanics, there are three types of mass or properties called mass: Inertial mass; passive gravitational mass; and active gravitational mass. Although inertial mass, passive gravitational mass and active gravitational mass are conceptually distinct, no experiment has ever unambiguously demonstrated any difference between them.
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Matter & Energy News
June 20, 2026
June 20, 2026 Researchers found that twisting layered sheets of hexagonal boron nitride can dramatically change the light produced by quantum emitters embedded within the material. The technique offers an unexpected new level of control over components that could ...
June 20, 2026 The global cobalt supply chain is more interconnected—and more vulnerable—than previously thought, with disruptions capable of triggering far-reaching cascades across multiple countries and industries. Researchers warn that protecting battery ...
June 17, 2026 A clever nanoscale redesign may have solved one of superconductivity’s biggest problems. Researchers in Sweden discovered that by subtly sculpting the surface beneath an ultrathin superconducting material, they could make it stay superconducting ...
June 16, 2026 Researchers discovered that hydrogen radicals generated by intense UV light can break down stubborn PFAS “forever chemicals” without added chemicals. The breakthrough reveals a key mechanism that could lead to greener and more effective ...
June 15, 2026 Scientists have found that staple-shaped particles can tangle together to create a material that is both strong and flexible. Unlike conventional materials, these particles can be locked into a sturdy structure or rapidly unraveled using vibrations. ...
June 15, 2026 Oxford physicists have created an entirely new type of Schrödinger’s cat-like quantum state using components that are themselves highly quantum in nature. The advance could open new possibilities for more resilient quantum computers and deeper ...
June 14, 2026 A new catalyst design could significantly improve the conversion of CO2 into methanol, an important fuel and chemical feedstock. Researchers separated key reaction steps across different catalyst sites, avoiding a long-standing trade-off between ...
June 12, 2026 A new nature-inspired membrane uses perfectly uniform one-nanometer pores to filter molecules with remarkable precision. The technology could transform industries such as pharmaceuticals and textiles by reducing energy consumption, improving water ...
June 12, 2026 Deep beneath the ground in China, the massive JUNO neutrino observatory has delivered its first major scientific breakthrough, achieving one of the most precise measurements yet of how elusive ...
June 12, 2026 Scientists at RIKEN have proposed a new way to make quantum systems synchronize in only one direction—like a one-way street for sound particles known as phonons. The breakthrough combines two quantum effects to create a form of one-way quantum ...
June 11, 2026 Scientists have developed an artificial photosynthesis system that essentially regulates itself, eliminating the need for batteries used in many current designs. The key innovation is an electrolyzer that automatically adapts to changing sunlight by ...
June 11, 2026 Scientists discovered that rice behaves in a highly unusual way: it weakens under rapid compression but stays stronger when pressure is applied slowly. Using this effect, they engineered a new ...
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June 19, 2026 Scientists have uncovered a surprising connection between quantum gravity and an exotic quantum state of matter that could explain why the universe isn’t expanding wildly fast. The study suggests ...
June 18, 2026 A new theory suggests the universe is constantly recording its own history in the fabric of spacetime. If correct, this cosmic memory could help solve some of the biggest puzzles in physics, from ...
June 16, 2026 Physicists have solved a long-standing problem involving systems that appear to violate Newton’s third law, such as bird flocks and bacterial ...
June 14, 2026 What if some black holes aren’t black holes at all? A new theoretical study suggests that when a massive star collapses, it might not form a singularity hidden behind an event horizon. Instead, the ...
June 13, 2026 A bold claim that the universe’s accelerating expansion was an illusion has been put to the test—and failed. Researchers found that the study behind the controversy made key mistakes when ...
June 11, 2026 Scientists found that transfer learning can make the search for new physics in the universe much faster, slashing the need for expensive simulations. Yet the approach can backfire when AI relies too ...
June 10, 2026 MIT researchers have shown that one fuel can power both chemical and electric spacecraft thrusters, potentially transforming what small satellites can do. The approach combines quick bursts of speed ...
June 9, 2026 The mysterious Amaterasu particle may not be a proton at all. New research suggests that some of the most extreme cosmic rays could be ultraheavy atomic nuclei, heavier than iron, which are better ...
June 8, 2026 What if our biggest idea about reality is built on a hidden misunderstanding? A new philosophical look at space-time challenges the popular view that the past, present, and future all exist together ...
June 8, 2026 Scientists used nanoscale gold metamaterials to supercharge heat transfer across tiny gaps, achieving up to four times more energy flow than similar ...