Tiny uranium crystals within the cores of white dwarf stars may set off nuclear reactions that blow the celebrities aside, Emily Conover reported in “Uranium ‘snowflakes’ may spark supernovas” (SN: 4/24/21, p. 5).
Two important varieties, or isotopes, of uranium on Earth are uranium-238 and uranium-235. However solely uranium-235 is fissile, or can maintain a fission chain response, reader Leon Maya famous, and this isotope is much less widespread. Maya questioned if the connection between the isotopes additionally extends to white dwarfs.
The quick reply is sure, Conover says. Since uranium-235 is fissile, it’s the isotope that would set off explosions in white dwarfs. And since it decays extra rapidly than uranium-238, uranium-235 is usually much less plentiful, whether or not on Earth or in white dwarfs.
Usually, scientists assume that a lot of the uranium current in planets and stars shaped from neutron star mergers (SN: 11/11/17, p. 6). Earth has a low focus of uranium-235 as a result of the merger that cast its uranium occurred fairly a very long time in the past, Conover says. “However a white dwarf that shaped quickly after a neutron star merger would have a considerably larger uranium-235 fraction than that on Earth.”
Tuning in to the cosmos
A distant galaxy cluster emits an uncommon radio wave sample that’s formed like a large jellyfish, Ken Croswell reported in “ ‘USS Jellyfish’ is a cosmic oddball” (SN: 4/24/21, p. 10).
Astronomers can detect the cluster at frequencies just like these of FM radio stations, Croswell reported. Reader Mike Neary questioned why researchers take into account these radio frequencies low, on condition that the frequencies reside within the Worldwide Telecommunication Union’s “very excessive frequency” band, which ranges from 30 to 300 megahertz.
Radio frequencies from 30 to 300 MHz are excessive for Earth however low for the cosmos, Croswell says. Take the Low Frequency Array, or LOFAR. This radio telescope community detects cosmic frequencies between 10 and 240 MHz, the bottom frequencies observable from Earth. In distinction, the best-known frequency in radio astronomy, emitted by hydrogen atoms in house, is 1,420 MHz, a wavelength of 21 centimeters.
Video killed the radio star
Zoom and the COVID-19 pandemic helped usher in a brand new age of videocalling, a expertise that customers had rejected for many years, Anushree Dave reported in “What took the videophone so lengthy to catch on?” (SN: 4/24/21, p. 22).
A number of readers mirrored on the expertise’s social influence and what videocalling may imply for the long run.
Reader Leah O’Connor lauded the advantages videocalling gives for people who find themselves deaf or have low listening to. “Zoom and another platforms now have computer-generated captioning that’s virtually higher than stay captioning,” she wrote. “Videocalling additionally permits for lip studying and American Signal Language.… I hope videocalling by no means goes away.”
Although many individuals have relied on videocalling through the pandemic to foster a way of togetherness and group, reader Mike Bushroe meditated on the adverse associations with the expertise that some individuals may develop. Folks might be taught to attach videocalling with the trauma of the pandemic, Bushroe famous, together with the shuttering of companies and public venues, the isolation from family members, the financial influence of all the roles misplaced and the chance of catching and probably dying from the virus. These adverse associations may persist lengthy after the pandemic, and other people might must heal from the trauma to “start to consider Zoom conferences and get-togethers solely on their very own deserves,” he wrote.
Whereas many readers seemed forward to videocalling’s future, Dave’s story reminded reader A. Michael Noll of his previous as a researcher at Bell Phone Laboratories and AT&T. “I revealed a lot in regards to the Picturephone and labored on video conferencing [technology] within the 1970s,” Noll wrote. He even contributed to the videophone sequence within the 1968 movie 2001: A House Odyssey.