Twisted space light could reveal brand-new physics
Broadcaster’s satellite fails in orbit
Atwist in the universe’s first light could hint that scientists need to rethink physics. Two Japanese scientists looked at the polarisation, or orientation, of light from the cosmic microwave background radiation, some of the earliest light emitted after the universe’s birth.
They found that the polarisation of photons, or light particles, might be slightly rotated from their original orientation when the light was first produced. And dark energy or dark matter may have been responsible for that rotation. Dark energy is a hypothetical force that is flinging the universe apart, while proposed dark matter is a substance that exerts gravitational pull, yet does not interact with light.
The rotated signature tells the scientists that something may have interacted with those photons – specifically something that violates a symmetry physicists call parity. This parity says that everything looks and behaves the same way, even in a flipped system – similar to how things look in the mirror. And if the system was following this parity rule, there wouldn’t be this rotation change.
Parity is shown by all subatomic particles and all forces except the weak force. However, the new results suggest that whatever the early light might have interacted with might be violating this parity. “Maybe there is some unknown particle, which contributes to dark energy, that perhaps rotates the photon polarisation,” said Yuto Minami, a physicist at the Institute of Particle and Nuclear Studies (IPNS) of the High Energy Accelerator Research Organization (KEK) in Japan.
When the cosmic microwave background radiation, or CMB, was first emitted 13.8 billion years ago, it was polarised in the same direction. Looking at how the light’s polarisation has rotated over time allows scientists to probe the universe’s history since that time by looking at how the light has changed as it travels across space and time.
Using the dusty Milky Way light, the scientists were able to figure out precisely how their instruments were oriented, so they knew the rotation in the light was real, not something caused by their instruments. This allowed them to determine the polarisation rotation of CMB light was non-zero, which means that the light has interacted with something that violates parity. It’s possible something in the early universe affected the light, but it’s more likely that it was something along the light’s path as it travelled towards Earth. That something could be dark energy or dark matter, which would mean that the particles that make up these mysterious substances violate parity.
The researchers reported their findings with 99.2 per cent confidence, meaning there’s an
8 in 1,000 chance of getting similar results by accident. However, this isn’t quite as confident as physicists require for absolute proof. For that they need five sigma, or 99.99995 per cent confidence, which likely isn’t possible with data from just one experiment. But future and existing experiments might be able to gather more accurate data, which could be calibrated with the new technique to reach a high enough level of confidence. “Our results do not mean a new discovery,” Minami said. “Only that we found a hint of it.”
“Maybe there is some unknown particle, which contributes to dark energy, that perhaps rotates the photon polarisation”
SiriusXM’s newest satellite, SXM-7, has suffered undisclosed failures during in-orbit testing, the company revealed in a filing with the US Securities and Exchange Commission on 27 January. “During in-orbit testing of SXM-7, events occurred which have caused the failure of certain SXM-7 payload units. An evaluation of SXM-7 is underway. The full extent of the damage to SXM-7 is not yet known,” SiriusXM said in the filing. At this time, it’s unclear if the satellite can be recovered.
The satellite, which was built by Maxar Technologies, launched on a SpaceX Falcon 9 rocket on 13 December. The company has said the failure was unrelated to the launch vehicle and that a full evaluation of the satellite is underway.
The SXM-7 satellite is based on Maxar Technologies’ SSL 1300 satellite bus. Powered by two large solar arrays and batteries for storage, it was designed to operate in the S-band spectrum, between 2.32 and 2.345 GHz. The satellite is part of a pair that Maxar built and SpaceX is launching for SiriusXM. The other, SXM-8, is still under construction and set to launch later this year. Each satellite has an operational lifetime of 15 years, and were intended to replace two aging satellites already in orbit. The satellites are designed to support SiriusXM’s digital radio service, providing coverage across the US, Canada and the Caribbean.
SXM-7 began its in-orbit testing phase on 4 January, which is a normal shakedown phase before a satellite enters service. The testing typically lasts for a few months. The company has yet to determine what went wrong, but says it is in control of the satellite.
Two Massachusetts school students – 16-year-old Kartik Pinglé and 18-year-old Jasmine Wright – have helped discover four new alien planets. Pinglé and Wright did their otherworldly work via the Student Research Mentoring Program (SRMP) at the Harvard-Smithsonian Center for Astrophysics and the Massachusetts Institute of Technology (MIT), which links up local high-school students with scientists for year-long projects. “By the end of the program, the students can say they’ve done active, state-of-the-art research in astrophysics,” SRMP director Clara Sousa-Silva, a quantum astrochemist at MIT, said.
Pinglé and Wright worked with Tansu Daylan, a postdoctoral researcher at MIT’s Kavli Institute for Astrophysics and Space Research. Daylan and his colleagues scrutinised observations of the Sunlike star HD 108236 made by NASA’s Transiting
Exoplanet Survey Satellite (TESS). TESS hunts for alien worlds via the transit method, noting the tiny but telltale dips in stars’ brightness caused when orbiting planets cross their faces from the spacecraft’s perspective.
The team confirmed four such planet-caused dips in the light curve of HD 108236, which lies about 200 light years from Earth. “I was very excited and very shocked,” Wright said. “We knew this was the goal of Daylan’s research, but to actually find a multi-planetary system, and be part of the discovering team, was really cool.”
Three of the four newfound worlds are gaseous planets slightly smaller than Neptune. The fourth is a super-Earth, a rocky planet a bit larger than our own, the researchers said. All four exoplanets lie very close to HD 108236; their orbital periods range from just under four Earth days to 19.5 Earth days.