Latest news with #FritzZwicky
Hans India
24-06-2025
- Science
- Hans India
Dark Matter: The cosmic puzzle that still evades discovery
In 1933, Swiss astrophysicist Fritz Zwicky made a groundbreaking observation while studying the Coma Cluster, a collection of galaxies over 300 million light-years away. He noticed the galaxies were spinning far too quickly to be held together by the visible matter alone. The only explanation? There had to be unseen mass providing the extra gravitational pull. He called it 'dunkle Materie' — dark matter. Nearly 100 years later, dark matter remains one of the greatest mysteries in science. It makes up around 27% of the universe, yet no one has ever seen it. It doesn't emit, reflect, or absorb light, making it completely invisible to telescopes. But without its gravitational influence, galaxies would fall apart, and the structure of the universe itself wouldn't exist. The Gravity We Can't See Evidence for dark matter is overwhelming. Stars on the edges of spiral galaxies rotate at speeds far too fast for visible matter alone to account for. Galaxy clusters move as though they're wrapped in vast, invisible halos. Even the early universe's structure — from galaxies to vast filaments of cosmic webbing — appears to have been shaped by something unseen holding it all together. At one point, scientists suspected neutrinos might be the answer. These ghost-like particles are abundant and barely interact with matter. But they're too light and too fast-moving to form the kind of gravitational scaffolding needed. Where Are the Particles? Physicists turned to more exotic candidates. One popular theory was WIMPs — Weakly Interacting Massive Particles. These theoretical particles could have mass and exert gravity, yet remain undetectable because they barely interact with ordinary matter. Deep underground labs were built with sensitive detectors waiting to catch a WIMP colliding with an atom. But decades have passed, and no clear signal has emerged. Supersymmetry offered another tantalizing idea — every known particle might have a heavier 'partner.' One such partner, the neutralino, seemed perfect for dark matter. Yet even after firing up the Large Hadron Collider, these hypothetical particles have never shown up. Now, physicists are widening the search. Some suspect dark matter might be made of ultra-light particles like axions, or that it resides in a hidden "dark sector" with its own rules and forces. Others are daring to rethink gravity itself — perhaps we don't need dark matter, just a new understanding of how gravity works. A Mystery That Could Rewrite Physics The stakes are massive. Cracking the dark matter code could transform our understanding of matter, forces, and the very origins of the universe. It could lead us to a new physics — one that goes beyond the Standard Model that currently explains everything from atoms to quarks. But for now, we remain in the dark. Dark matter doesn't shine, collide, or leave trails. All we know is that it's out there — shaping galaxies, pulling clusters together, and silently sculpting the universe. Until we find it, the cosmos will remain a place of wonder and unfinished questions — where the most powerful force holding everything together remains hidden in plain sight.
Indian Express
24-06-2025
- Science
- Indian Express
Dark matter mystery: Why there isn't no light yet after decades of search
In 1933, Swiss astrophysicist Fritz Zwicky was observing the Coma Cluster — a massive congregation of galaxies about 300 million light-years away — when he noticed something odd. The galaxies were swirling around each other far too fast. According to the visible matter in the cluster, they should have flown apart long ago. 'There must be some missing mass,' Zwicky concluded. Matter that was invisible, yet exerted a gravitational pull strong enough to hold the cluster together. He called it 'dunkle Materie,' or dark matter. Nearly a century later, that missing matter still haunts modern physics. We now know that everything we can see — stars, planets, gas, dust — makes up only about 5% of the universe. Another 27% is this elusive dark matter, which neither emits nor absorbs light, making it undetectable by traditional telescopes. Yet without it, galaxies would not hold together, and the cosmic web that binds the universe would fall apart. One of the most compelling clues to dark matter comes from the way galaxies move. Stars at the outer edges of spiral galaxies rotate much faster than expected — far too fast for the visible matter alone to account for. Without something unseen providing extra gravity, these galaxies should spin apart like leaves in a storm. Galaxy clusters, too, behave as if they are embedded in vast halos of invisible mass. Dark matter, then, acts like the hidden scaffolding of the cosmos — an unseen framework on which galaxies, clusters, and cosmic filaments are built. This gravitational scaffold shaped the formation of structure in the early universe and continues to hold it all together today. For a time, scientists hoped that neutrinos — extremely light, ghost-like particles that stream through the cosmos in unimaginable numbers — might be the missing glue. But although neutrinos do have mass, it's now clear that they move too fast and don't clump together the way dark matter must. Instead of forming scaffolding, they pass through matter like whispers, too fleeting to do the heavy lifting. The big question is: what is dark matter made of? For years, physicists hoped it was a new kind of particle. One popular idea was the WIMP — the weakly interacting massive particle. These hypothetical particles wouldn't interact with ordinary matter much, which is why we can't see them, but they would have mass and gravity. To find them, physicists built sensitive detectors in deep underground labs — shielded from cosmic rays and background radiation. These detectors waited for the rare event when a WIMP might bump into an atom. But so far, no unmistakable signal has emerged. One reason is that dark matter seems to interact with the rest of the universe through gravity alone, and not via electromagnetic or nuclear forces, making it extraordinarily difficult to catch in the act. As experiments continue to come up empty-handed, scientists are beginning to wonder whether our assumptions about the nature of dark matter might need to be revised—or whether it lies hidden in a realm we've yet to imagine. Another promising theory came from supersymmetry, a grand idea that predicted a heavier 'partner' for every known particle. Some of these partners, like the neutralino, seemed to be perfect dark matter candidates. But again, when the Large Hadron Collider turned on, these particles were nowhere to be found. It's now been decades, and dark matter still hasn't shown its face. One by one, the most obvious possibilities are being ruled out. The more massive, easier-to-detect particles haven't turned up. That's pushing researchers to think beyond the standard playbook — maybe dark matter consists of incredibly light particles like axions, or exists in a hidden 'dark sector' with its own forces. It's also possible we've been asking the wrong question. Some radical theories propose that our understanding of gravity itself may be incomplete — and that there is no dark matter at all. But so far, these modified gravity theories can't explain the full range of observations. The stakes are high. Solving the dark matter puzzle could change how we understand matter, forces, and the origin of structure in the cosmos. It may open doors to new physics beyond the Standard Model — our current best theory of particles and forces. But for now, dark matter remains a mystery. It doesn't shine, it doesn't collide, it doesn't leave fingerprints. And yet its gravitational pull shapes the largest structures in the universe. Perhaps the next generation of detectors will catch it. Perhaps the answer lies in a theory not yet imagined. Until then, we live in a universe where the majority of matter is invisible — felt, but not seen. As strange as that sounds, it may just be the universe's way of reminding us that our understanding is still incomplete, and that the cosmos is larger — and darker — than we ever imagined.
