Reference Terms
from Wikipedia, the free encyclopedia
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.
Related Stories
1
2
Matter & Energy News
May 20, 2026
May 20, 2026 Scientists in Canada have discovered that ancient underground rocks are naturally producing hydrogen gas — and lots of it. Measurements from mine boreholes in Ontario show the gas can flow continuously for years, offering a potential new source of ...
May 20, 2026 Researchers have developed a light-driven method for creating tiny, high-energy “housane” molecules that are valuable for drug development and materials science. These compact ring-shaped structures are difficult to produce because of the ...
May 19, 2026 Scientists spent decades chasing signs of a mysterious new force hidden inside the muon, one of nature’s strangest particles. But after years of supercomputer calculations, researchers discovered the apparent anomaly was likely a calculation error ...
May 18, 2026 Scientists at the University of Cambridge have achieved what was once considered impossible by electrically powering insulating nanoparticles to create a completely new kind of LED. Using tiny organic “molecular antennas,” the team found a way ...
May 18, 2026 Researchers have developed a durable new catalyst that produces clean hydrogen without relying on expensive platinum metals. The breakthrough could make renewable hydrogen fuel cheaper, more efficient, and easier to scale for real-world energy ...
May 18, 2026 Electric vehicles are pushing scientists to tackle one of the biggest hidden energy drains inside electric motors: magnetic energy loss. Now, researchers in Japan have developed a powerful AI-driven ...
May 17, 2026 Scientists have achieved something that once sounded almost impossible: using ordinary sunlight to create quantum-linked photon pairs, a phenomenon normally dependent on precise laboratory lasers. By building a sun-tracking system that funnels ...
May 14, 2026 Scientists at UC Santa Barbara have created a remarkable new material that works like a “rechargeable solar battery,” storing sunlight inside tiny molecules and releasing it later as heat — ...
May 13, 2026 Scientists in Japan have developed a new way to instantly detect elusive quantum “W states,” a major milestone for quantum technology. The breakthrough could help unlock faster quantum communication, teleportation, and powerful new computing ...
May 13, 2026 A new quantum-inspired algorithm has cracked a problem so massive that conventional supercomputers struggle to even approach it. Researchers used the method to simulate extraordinarily complex quantum materials known as quasicrystals, opening the ...
May 10, 2026 A team at the University of Hong Kong has developed a new “super steel” that can survive the harsh conditions needed to make green hydrogen from seawater. The material uses an unexpected double-protection mechanism that resists corrosion far ...
May 9, 2026 Scientists have taken a major step toward ultra-secure quantum communication by demonstrating a remarkably stable quantum encryption system that worked across more than 120 kilometers of optical fiber. Using tiny semiconductor quantum dots that emit ...
Latest Headlines
updated 12:56 pm ET
May 19, 2026 Black holes crashing together may be revealing clues about dark matter hidden across the universe. Physicists created a new model predicting how dark matter could subtly distort gravitational waves ...
May 19, 2026 Physicists may have uncovered a surprising new clue that string theory—the idea that the universe is built from unimaginably tiny vibrating strings—could be more than just a mathematical fantasy. ...
May 18, 2026 For more than 200 years, scientists have struggled to pin down the exact strength of gravity — and one physicist spent a decade chasing the answer ...
May 14, 2026 Scientists studying mysterious ultra-powerful cosmic rays have uncovered a surprising hidden pattern that could finally help explain where these particles come from. Using the DAMPE space telescope, ...
May 13, 2026 For nearly 100 years, reinforced rubber has powered everything from car tires to airplanes, yet scientists never fully understood why adding tiny particles of carbon black made rubber so incredibly ...
May 11, 2026 Scientists have pulled off a mind-bending quantum experiment that sounds almost impossible: they showed that tiny metal particles made of thousands ...
May 9, 2026 A major obstacle may be standing in the way of the next generation of ultra-tiny computer chips. Researchers discovered that many promising 2D materials lose their advantages because an invisible ...
May 9, 2026 Physicists may have just cracked open a hidden side of the quantum world. For decades, every known particle was thought to belong to one of two categories — bosons or fermions — but researchers ...
May 8, 2026 Scientists may have uncovered a surprising secret behind why life exists at all. A new study suggests that the Universe’s fundamental constants — ...
May 6, 2026 In a major breakthrough, scientists have experimentally confirmed a universal growth law in two dimensions using a quantum system of fleeting light–matter particles. The finding strengthens the ...