One cluster or two?

the gist

The galaxy cluster Abell 3192 was first catalogued as a single cluster, but measurements showed it is actually two separate clusters at different distances. The nearer group lies about 2.3 billion light-years away and the farther one about 5.4 billion light-years away. Both are enormous, with masses thought to be roughly 30 and 120 trillion times the Sun's. Their combined mass bends light from more distant galaxies, which is why background galaxies appear stretched into curved arcs. This acts as a natural gravitational lens.

how it works

Massive objects curve spacetime, so light from distant galaxies passing nearby is deflected, much like a lens bends light. The cluster's dark matter provides most of the mass, so the amount of distortion reveals how the mass is spread out. Two peaks in that distortion pointed to two clusters.

so what

Clusters like this let astronomers measure dark matter indirectly, by how strongly they bend light, and they can be mistaken for single objects when seen only in projection. Telling them apart changes how mass is mapped across the universe.

the bigger pattern

Gravitational lensing has been used since the 1979 discovery of the first lensed quasar to map dark matter in clusters, and reclassifications of catalogued objects are common as surveys improve.

fun fact

Gravitational lensing was predicted by Einstein's general relativity, and it is one of the main ways astronomers map dark matter.

ESA/Hubble · CC BY 4.0

Image: ESA/Hubble & NASA, G. Smith, H. Ebeling, D. Coe

source: ESA/Hubble ↗

historyThe Public Domain Review1909 · United States

D. W. Griffith’s A Corner in Wheat (1909)

the gist

In 1909 D. W. Griffith made a 14-minute film about a speculator who corners the wheat market and doubles the price of bread. A farmer sows his field while a 'Wheat King' gambles in the Chicago wheat pit; bakers raise the loaf from five cents to ten and the poor line up for bread. Griffith cut back and forth between the farm, the feast and the breadline, a technique called parallel editing, so audiences saw both ends of the economy at once. The film drew on Frank Norris's stories and on a real scheme: months earlier Chicago financier James Patten had cornered wheat, sent bread prices up and made about $5 million, roughly $185 million today.

how it works

To corner a market, a trader buys up most of the available supply and the futures contracts that promise more. Anyone who has to deliver the commodity must then buy from the cornerer at whatever price is demanded. The trader profits until the stock is released or the scheme collapses.

so what

A century on, it still shows how markets can be rigged by someone who controls supply, and how the people at either end, farmers and eaters, pay for it. It also helped establish editing as a way to argue a point, not just tell a story.

the bigger pattern

Corners have recurred whenever supply could be locked up, from the Hunt brothers' attempt on silver in 1979 to 1980 to the 'Black Friday' gold panic of 1869. Many such schemes end by collapsing, and the response is often new rules on speculation.

fun fact

In the film the Wheat King dies by falling into a grain elevator and being buried in the wheat he hoarded, an ending borrowed from Norris's novel The Octopus.

more on this

background

A Corner in Wheat is a 1909 American short silent film which tells of a greedy tycoon who tries to corner the market in wheat, destroying the lives of the people who can no longer afford to buy bread. It was directed by D. W. Griffith and adapted by Griffith and Frank E. Woods from a novel and a short story by Frank Norris, titled The Pit and "A Deal in Wheat". Griffith may have had a real-life inspiration: six months earlier, James A. Patten had actually cornered the market in wheat, and in some cities, the price of bread doubled from five cents to ten, just as in the movie.

In 1994, A Corner in Wheat was selected for preservation in the United States National Film Registry by the Library of Congress as being "culturally, historically, or aesthetically significant".

From Wikipedia: A Corner in Wheat (CC BY-SA 4.0) ↗

see

D. W. Griffith, Public domain, via Wikimedia Commons

G. W. Bitzer (cinematographer) under employment of the Biog…, Public domain, via Wikimedia Commons

DS Pugh, CC BY-SA 2.0, via Wikimedia Commons

Image: The Public Domain Review

source: The Public Domain Review ↗

12 min

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from ABC News In-depth

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A new autobiography by former Test cricketer Usman Khawaja has made explosive revelations about the Australian Test team's 2018 ball-tampering saga in South Africa.

7.30 host Sarah Ferguson speaks to Usman Khawaja.

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