Extragalactic cosmic ray Extragalactic cosmic ray Extragalactic cosmic rays are very-high-energy particles that flow into the Solar System from beyond the Milky Way galaxy. The energies these particles possess are in excess of 10 eV. Unlike solar or galactic cosmic rays, little is known about the origins of extragalactic cosmic rays. This is largely due to a lack of statistics: only about 1 extragalactic cosmic ray particle per square meter per year reaches the Earth's surface (see figure). There are many ideas about which processes may be responsible for cosmic rays with such high energies. In the 'bottom-up' approach, cosmic rays gain more
The Post Card: From Socrates to Freud and Beyond The Post Card: From Socrates to Freud and Beyond The Post Card: From Socrates to Freud and Beyond () is a 1980 book by French philosopher Jacques Derrida. It is a "satire of epistolary literature." After "Glas" (1974), it is sometimes considered Derrida's most "literary" book, and continues the critical engagement with psychoanalysis first signaled in "Freud and the Scene of Writing" from Derrida's "Writing and Difference" (1967). The first half of the book, titled "Envois" (sendings), contains a series of love letters addressed by Derrida to an unnamed loved one. In one of the letters, dated 6 June 1977,