Latest news with #ScottKravitz
Gizmodo
08-07-2025
- Science
- Gizmodo
Record-Setting Dark Matter Detector Comes Up Empty—and That's Good News
WIMPs (weakly interacting massive particles) are one of the most serious contenders for dark matter—the 'missing' mass supposedly constituting 85% of our universe. Given its elusiveness, dark matter tests the patience and creativity of physicists. But the latest results from LUX-ZEPLIN (LZ), the South Dakota-based detector, may have brought scientists a small step closer to catching WIMPs in action. In a recent Physical Review Letters paper, scientists analyzed 280 days' worth of data from LUX-ZEPLIN, reporting the tightest ever upper limit on WIMPs. The result—a near fivefold improvement—demonstrates how physicists are increasingly getting better at circumventing the problem that dark matter is, well, dark; the elusive stuff evades any detection method that depends on materials interacting with visible light or other types of radiation. There's ample evidence to suggest that dark matter does in fact exist, including numerous astrophysical observations hinting at some invisible matter exerting gravitational force on objects we can see. Physicists, as a result, tend to use materials that we can see, such as liquid forms of heavyweight elements like xenon, and simply wait for some unknown particle to interact with it. That strategy—waiting for particles to interact with heavy elements—is a well-tested approach for detecting WIMPs, hypothetical particles that interact with gravity but on a scale so tiny that only the most sensitive detectors might catch a glimpse. The LUX-ZEPLIN experiment, located one mile underground in a decommissioned South Dakota gold mine, employs nearly 15,000 pounds (7 tons) of liquid xenon. The chemical element's high atomic mass and density make it potentially easier for scientists to detect any unknown particles that may pass through the detector. Also, liquid xenon is transparent, preventing any unwanted noise—usually arising from radioactive matter around the detector—from spoiling an experiment. 'If you think of the search for dark matter like looking for buried treasure, we've dug almost five times deeper than anyone else has in the past,' said Scott Kravitz, a physicist at the University of Texas at Austin and deputy coordinator for LZ, in a press release. 'That's something you don't do with a million shovels—you do it by inventing a new tool.' The latest experiment also represents the first time the LZ team applied a technique called 'salting,' in which false WIMP signals were added in advance. This helped the researchers—who, of course, would love to find dark matter—avoid bias and stay skeptical of potentially promising signals. 'There's a human tendency to want to see patterns in data, so it's really important when you enter this new regime that no bias wanders in,' said Scott Haselschwart, a physicist at the University of Michigan and LZ physics coordinator, in the same release. 'If you make a discovery, you want to get it right.' The next steps for the LZ experiment are to continue pressing against the upper limit for WIMPs and utilize the detector's cutting-edge technology to probe other interesting and rare physics processes, explained Amy Cottle, a physicist at University College London also involved with LZ, in the statement. 'We've demonstrated how strong we are as a WIMP search machine, and we're going to keep running and getting even better—but there's lots of other things we can do with this detector,' she said.
CBS News
01-06-2025
- General
- CBS News
San Francisco parents concerned over implementation of school district's ethnic studies class
San Francisco Unified School District parents are speaking out now that the district is requiring ninth graders to take a two-semester ethnic studies class. Just days before the 2024-25 school year, SFUSD sent an email to parents of incoming freshmen notifying them that their kids were enrolled in a yearlong ethnic studies class, something that was previously an elective. "It's teaching to a particular ideology, not actual history," said parent Viviane Safrin. She said she supports ethnic studies, but she's concerned about how this course is being implemented. "This course for our freshman has replaced world history," explained Safrin. "Our ninth graders are saying I took this course already in middle school and why am I having to take it again as a ninth grader for a full year?" It covers topics like racism, activism, and comparing the merits of capitalism versus socialism. "When I looked at what was being taught in this course, we've gone too far," said Safrin about what she saw in the curriculum published online. "And it's okay to say we've gone too far." Parent Scott Kravitz agrees. "I feel that instead of fostering critical thinking or knowledge, all that we're doing is creating ill-informed activists," Kravitz said. In 2021, a California bill required all high schools to offer an ethnic studies course by the 2025-2026 school year. It needs to become a graduation requirement by the 2029-30 school year. District leaders say they moved forward with the mandate properly, but parent Alex Wong questions that. "The president of the board at the time, Lainie Motamedi, said, 'Let's slow this down,' and the fact that SFUSD just continued to barrel through kind of just made me hesitant on why is everything being rushed when there's still a lot of questions to be answered about this," Wong said. Ethnic studies has been offered as an elective for about a decade. Wong said mandating a two-semester class will leave students missing out on other topics. "I think the problem with SFUSD is it's a full-year course," said Wong. "The state law only requires one semester. There are only so many days in the school year, and the fact that you're required to take an extra semester and leaves less time to take other classes kids may be interested in." On the state level, there are still four years before an ethnic studies class is required for graduation. All the parents CBS Bay Area spoke with hope SFUSD uses the extra time to re-evaluate the course. "Our city schools are reflective of the best of our society," said Safrin. "We want to raise our kids here and provide the highest quality, rigorous curriculum. Giving our kids many choices and opportunities to learn."
