- Why in news
- On 30 September 2026, the CHIME radio telescope in Canada reported its first standalone detection of hydrogen's faint radio glow from when the universe was about five billion years old. Researchers from the Raman Research Institute, India, were part of the study, published in The Astrophysical Journal.
- What it is
- CHIME is the Canadian Hydrogen Intensity Mapping Experiment, a radio interferometer in Canada. It was built to map neutral hydrogen across the early universe and so trace cosmic expansion and dark energy. It has no moving parts and scans the sky as the Earth rotates.
- What CHIME is for
- It is an interferometric radio telescope built to map hydrogen gas in the early universe. This lets astronomers calculate cosmic expansion and probe dark energy.
- What is new
- CHIME detected the hydrogen signal using only its own data. Earlier it had to cross-correlate with galaxy survey data from other telescopes.
- Epoch and data
- The signal comes from when the universe was about five billion years old. It is based on 94 nights of data collected in 2019.
- Hydrogen share
- About two per cent of the universe's hydrogen was in neutral atomic form at that time, broadly consistent with other measurements.
- Indian role
- Researchers at the Raman Research Institute, an autonomous institute of the Department of Science and Technology, are CHIME collaborators.
- Neutral hydrogen line
- Neutral hydrogen emits radio waves at a wavelength of about 21 cm, which is the signal intensity mapping targets.
Don’t confuse with Intensity mapping vs galaxy surveys: Intensity mapping measures the combined radio glow of hydrogen over large areas. Galaxy surveys use light to detect individual galaxies in fine detail.
Don’t confuse with Dark energy vs dark matter: Dark energy is the force thought to drive the accelerating expansion of the universe. Dark matter is unseen matter that acts through gravity.
Science and technology: 57 Prelims questions since 2013; most test the concept behind the news, not the news itself. In Mains, 12 news-triggered questions.
Why it matters
- It offers a faster, cheaper way to study dark energy, one of physics' biggest open questions.
- It can test competing dark energy theories independently and show how galaxies form and evolve.
Problems
- The faint signal is buried in noise from the cosmic background, human technology and the instrument itself.
Way forward
- Extend the analysis to nearly seven years of data and to earlier epochs, when the universe was about three billion years old.
Put in your answer
Cost advantage of intensity mapping: Galaxy surveys cost millions more and cover only the part of the universe hot and dense enough to form stars. CHIME can probe larger scales and earlier times at a fraction of the cost.
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No practice question for this one; the card may still help an answer. Why: Space science topic with dark energy concept; sci-tech is 57 of 327 Prelims questions, but the facts here are thin.
Worth revising until Prelims 2028: most news questions come within two years of the event.