Cloud Seeding and Water Bankruptcy, Prolonged Grief Disorder, and Dark Matter at the Galactic Center

Overview

New Scientist's weekly science program surveys three major topics: water bankruptcy and a new cloud seeding technique in the US West, the emerging understanding of prolonged grief disorder and its brain correlates, and the provocative idea that dark matter could imitate the galaxy’s central black hole Sagittarius A*.

What to expect

The episode explains how water scarcity is reshaping policy and technology, describes a cloud ionization method that researchers say boosted snowfall by about 20%, and discusses the limitations and controversies around weather modification. It then delves into prolonged grief disorder, its diagnostic criteria, brain findings, and treatment options. Finally, it explores a recent theoretical scenario in which a dark matter clump could reproduce the observations attributed to a black hole, and what tests might distinguish the two possibilities in the future.

Water scarcity and cloud seeding

The program starts from the idea that the world is running out of renewable water as demand grows and groundwater is depleted. The UN framing introduces the notion of water bankruptcy, where rainfall and recharge occur over timescales far longer than human lifetimes. Cloud seeding is presented as a potential remedy that has been pursued for decades, with a recent Utah study claiming a 20% increase in snowfall via a cloud ionization technique. The technique uses a high voltage across a wire between two pylons to charge aerosols in dry air; charged particles attract and form bigger droplets, potentially increasing precipitation. The show notes that most scientists view cloud seeding as localized and modest in effect, and the cost of large scale deployment may limit its impact. Debates around environmental risk, conspiracy theories, and cross-border water transfer are discussed, highlighting the complexity of actually shifting regional water supplies.

Prolonged grief disorder

The episode then covers prolonged grief disorder, a condition recognized by the American Psychiatric Association in 2022. It affects about 5% of bereaved individuals and is diagnosed when symptoms persist beyond a 6 month threshold and interfere with daily life. The discussion summaries findings from brain-imaging studies comparing prolonged grief disorder with typical grief, depression, anxiety, and PTSD. Differences include heightened activity in reward-related brain circuits and stronger attention to reminders of the deceased, suggesting impaired emotional regulation. The show covers practical implications, such as identifying people at risk (limited social support, violent or unexpected death, ICU deaths) and offering grief-specific therapies and peer support; antidepressants may help when grief overlaps with depression.

Dark matter at the Galactic Center

Finally, the program investigates a provocative idea that Sagittarius A* could be a clump of fermionic dark matter in a specific mass range. The researchers argue that such a clump could mimic the observed orbits and dynamics near the galactic center, though this is not the simplest explanation and would not apply to all data. The discussion includes how the Event Horizon Telescope image of the black hole’s shadow is not yet precise enough to distinguish a dark matter clump from a true black hole, and what future high-resolution observations or orbital measurements could reveal. The segment ends by noting the scientific openness to novel ideas while emphasizing the need for robust evidence.

Takeaways

Across these topics, the episode highlights how science advances through new measurements, careful interpretation, and ongoing debate about limitations and alternatives. It also underscores the practical questions of whether technologies like cloud seeding can meaningfully address water insecurity and how we approach complex emotions and brain function in grief, alongside fundamental questions about the universe’s missing matter.