Backer's early work focused on
pulsars. He discovered the first
millisecond pulsar,
PSR B1937+21, which rotates at 642 Hz (1.558 ms), a rate far beyond what was expected of pulsars before its discovery. Backer was also involved in the discovery of a
Jupiter-sized planet around
PSR B1620-26, thought to be the oldest known extrasolar planet. Backer pioneered efforts to detect
gravitational waves from rapidly rotating
neutron stars, aiming to set limits on the gravitational wave background of the
universe. Backer was also a pioneer in
Very Long Baseline Interferometry, a technique in radio astronomy used to achieve high angular resolution images of astronomical sources. His efforts here were directed towards understanding
Sagittarius A*, the
supermassive black hole at the center of the
Milky Way. These arrays are simple long wavelength telescopes that hope to detect the
redshifted hydrogen line from a time very early in the
history of the universe when
hydrogen was neutral, and by doing so study the first objects that formed in the universe. ==Honors==