On 23 April, NASA’s Swift orbiter detected the most distant and therefore earliest stellar object ever seen. 1 With a record redshift z of 8.26, the gamma-ray burst recorded by Swift is presumed to manifest the collapse of a rapidly spinning massive star—a collapsar—to a black hole about 625 million years after the Big Bang. In fact, GRB090423 is earlier than anything yet observed, at any electromagnetic wavelength, except the cosmic microwave background.
No redshift as high as 7 has ever been confirmed for a galaxy or quasar, or for any previous GRB. (Supernovae, not in the same league, are rarely seen with z beyond 2.) But typical GRBs are luminous enough to be detectable at least out to z = 20, corresponding to 180 Myr after the Big Bang—if there were any back then. Harvard University theorist Avi Loeb has been arguing for a decade that GRBs beyond...
