TODAY IN THE HISTORY OF PSYCHOLOGY
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28 agosto 2016
Abell 370: Galaxy Cluster Gravitational Lens
What is that strange arc? While imaging the cluster of galaxies Abell 370, astronomers had noted an unusual arc to the right of many cluster galaxies. Although curious, one initial response was to avoid commenting on the arc because nothing like it had ever been noted before. In the mid-1980s, however, better images allowed astronomers to identify the arc as a prototype of a new kind of astrophysical phenomenon -- the gravitational lens effect of entire cluster of galaxies on background galaxies. Today, we know that this arc actually consists of two distorted images of a fairly normal galaxy that happened to lie far behind the huge cluster. Abell 370's gravity caused the background galaxies' light -- and others -- to spread out and come to the observer along multiple paths, not unlike a distant light appears through the stem of a wine glass. In mid-July of 2009, astronomers used the then just-upgraded Hubble Space Telescope to image Abell 370 and its gravitational lens images in unprecedented detail. Almost all of the yellow images featured here are galaxies in the Abell 370 cluster. An astute eye can pick up many strange arcs and distorted arclets, however, that are actually images of more distant galaxies. Studying Abell 370 and its images gives astronomers a unique window into the distribution of normal and dark matter in galaxy clusters and the universe.
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Mother and daughter taking a walk in New York City. 1970.
Mother and daughter taking a walk in New York City. 1970.
Although Hammurabi often gets credit for the “first” law code,...
Although Hammurabi often gets credit for the “first” law code, the title should actually go to another, earlier king. An otherwise obscure Sumerian king called Ur-Nammu wrote the first known law code 300 years earlier. Unfortunately for Ur-Nammu’s reputation, much of his code is unreadable, and it has survived only in fragments. Hammurabi’s code is complete. Poor Ur-Nammu remains obscure, while every schoolchild knows the name Hammurabi.
vox: Did you know? The most dangerous drugs in America are...
vox:
Did you know? The most dangerous drugs in America are perfectly legal.
As German Lopez writes, “There’s one aspect of the war on drugs that remains perplexingly contradictory: some of the most dangerous drugs in the US are perfectly legal.” This chart uses data from the Centers for Disease Control and Prevention to make a counterintuitive point: the deadliest drugs in America are legal. In some cases, those drugs are deadlier because their legal status makes them more widely available. If heroin were as easy to get as tobacco, more people would surely die from it each year. But that’s not true in all cases. Alcohol is much more dangerous than marijuana, but marijuana is illegal in most states, while alcohol is legal for those over age 21.
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