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
January 20, 2026
Jan. 19, 2026 Physicists have unveiled a new way to simulate a mysterious form of dark matter that can collide with itself but not with normal matter. This self-interacting dark matter may trigger a dramatic collapse inside dark matter halos, heating and ...
Jan. 19, 2026 As global energy demand surges—driven by AI-hungry data centers, advanced manufacturing, and electrified transportation—researchers at the National Renewable Energy Laboratory have unveiled a breakthrough that could help squeeze far more power ...
Jan. 18, 2026 Solid-state batteries could store more energy and charge faster than today’s batteries, but they tend to crack and fail over time. Stanford researchers found that a nanoscale silver treatment can greatly strengthen the battery’s ceramic core. ...
Jan. 17, 2026 Engineers have created a device that generates incredibly tiny, earthquake-like vibrations on a microchip—and it could transform future electronics. Using a new kind of “phonon laser,” the team ...
Jan. 15, 2026 Foams were once thought to behave like glass, with bubbles frozen in place at the microscopic level. But new simulations reveal that foam bubbles are always shifting, even while the foam keeps its overall shape. Remarkably, this restless motion ...
Jan. 12, 2026 Florida State University scientists have engineered a new crystal that forces atomic magnets to swirl into complex, repeating patterns. The effect comes from mixing two nearly identical compounds whose mismatched structures create magnetic tension ...
Jan. 9, 2026 Scientists in South Korea have discovered a way to make all-solid-state batteries safer and more powerful using inexpensive materials. Instead of adding costly metals, they redesigned the battery’s internal structure to help lithium ions move ...
Jan. 8, 2026 A team of physicists has discovered a surprisingly simple way to build nuclear clocks using tiny amounts of rare thorium. By electroplating thorium onto steel, they achieved the same results as years of work with delicate crystals — but far more ...
Jan. 8, 2026 Nearly everything in the universe is made of mysterious dark matter and dark energy, yet we can’t see either of them directly. Scientists are developing detectors so sensitive they can spot particle interactions that might occur once in years or ...
Jan. 7, 2026 Researchers have built a new platform that produces ultrashort UV-C laser pulses and detects them at room temperature using atom-thin materials. The light flashes last just femtoseconds and can be ...
Jan. 6, 2026 Scientists are learning to engineer light in rich, multidimensional ways that dramatically increase how much information a single photon can carry. This leap could make quantum communication more secure, quantum computers more efficient, and sensors ...
Jan. 6, 2026 A new chip-based quantum memory uses nanoprinted “light cages” to trap light inside atomic vapor, enabling fast, reliable storage of quantum information. The structures can be fabricated with extreme precision and filled with atoms in days ...
Latest Headlines
updated 12:56 pm ET
Jan. 15, 2026 Physicists have long relied on the idea that electrons behave like tiny particles zipping through materials, even though quantum physics says their exact position is fundamentally uncertain. Now, ...
Jan. 15, 2026 Dark matter, one of the Universe’s greatest mysteries, may have been born blazing hot instead of cold and sluggish as scientists long believed. New research shows that dark matter particles could ...
Jan. 13, 2026 At extreme pressures and temperatures, water becomes superionic — a solid that behaves partly like a liquid and conducts electricity. This unusual form is believed to shape the magnetic fields of ...
Jan. 12, 2026 Scientists at Fermilab’s MicroBooNE experiment have ruled out the existence of the elusive sterile neutrino, a particle proposed for decades to ...
Jan. 12, 2026 Scientists observing the red giant star R Doradus have found that starlight isn’t strong enough to drive its stellar winds, overturning a ...
Jan. 11, 2026 The accelerating expansion of the universe is usually explained by an invisible force known as dark energy. But a new study suggests this mysterious ...
Jan. 8, 2026 Einstein’s claim that the speed of light is constant has survived more than a century of scrutiny—but scientists are still daring to test it. Some theories of quantum gravity suggest light might ...
Jan. 8, 2026 When scientists repeatedly drove a strongly interacting quantum system with laser “kicks,” they expected it to heat up and grow chaotic. Instead, the atoms abruptly stopped absorbing energy and ...
Jan. 7, 2026 Researchers at TU Wien have discovered a quantum system where energy and mass move with perfect efficiency. In an ultracold gas of atoms confined to a single line, countless collisions occur—but ...
Jan. 5, 2026 Scientists have found a way to see ultrafast molecular interactions inside liquids using an extreme laser technique once thought impossible for fluids. When they mixed nearly identical chemicals, one ...