Galaxies can shine with forbidden light that lab rules say should not exist

the gist

MCG-01-24-014 is a spiral galaxy about 275 million light-years away with an extremely energetic core, an active galactic nucleus, making it a Type-2 Seyfert galaxy. Its light contains forbidden emission lines, spectral lines that standard quantum rules say are too improbable to appear. Those rules are built on assumptions that hold in laboratory conditions on Earth. In the dense, energetic gas near a galactic core, the assumptions fail, so these transitions happen and the light escapes toward us.

how it works

Atoms emit light at specific wavelengths when electrons drop between allowed energy levels. Some transitions are rare because they depend on the atom being isolated and at low density. In a dense galactic core the gas is constantly disturbed, so these rare transitions occur often enough to produce bright lines.

so what

Spectra are one of astronomers' main tools for reading distant objects, so knowing which lines are forbidden on Earth but common in space matters for interpreting them. It is a clear case of extreme environments revealing physics that ordinary labs cannot reproduce.

ESA/Hubble · CC BY 4.0

Image: ESA/Hubble & NASA, C. Kilpatrick

source: ESA/Hubble ↗

historyWikipediaclassic1336–1565 · Karnataka, India

Hampi was once one of the world's largest cities, until its Vijayanagara capital was destroyed in 1565

the gist

Hampi is a UNESCO World Heritage Site in Karnataka, India, with more than 1,600 surviving remains spread over 4,100 hectares. It was the capital of the Vijayanagara Empire from 1336 to 1565. Travellers from Persia and Portugal described it as a prosperous, wealthy and grand city with temples, markets and farms along the Tungabhadra River. By 1500 it was estimated to be the world's second-largest city after Beijing, and probably India's richest at the time. In 1565 a coalition of Muslim sultanates defeated the Vijayanagara Empire, its capital was conquered and destroyed, and the city was left in ruins. Hampi remains a religious centre, with the active Virupaksha Temple at its heart.

how it works

The city was built around a fortified core with temples, markets and water structures along the river, supplied by an extensive network of roads and waterworks. When the empire fell, the city was not rebuilt, so its stone monuments were left standing.

so what

Hampi shows how quickly a great city can vanish after a military defeat, and how a ruined capital can remain sacred. Its ruins give historians a view of medieval South Asia that few other sites can match.

fun fact

The name Hampi comes from Pampa, an old name for the Tungabhadra River.

From Wikipedia, the free encyclopedia · text CC BY-SA 4.0

Image: Wikimedia Commons

source: Wikipedia ↗

2 min

politicsshortCNA2:01

False allegations about Singapore’s hand in Indonesia’s markets and a made-up meeting

from CNA

CNA Verify has found close to 400 posts pushing falsehoods tying Singapore to Indonesia’s stock market rout and to a secret meeting that never took place. Together, they drew nearly 12 million views, and some were circulated by accounts that appeared to be working in concert, across multiple social media platforms.

Here’s how the disinformation campaign targeting Singapore was uncovered.

on YouTube: CNA ↗