Capping the length of extra dimensions

Size and age of recently discovered black hole shrinks braneworld

Red alert: Scientists are shrinking branes.

BRANE-SHRINKER This illustration depicts a stellar-mass black hole feeding on stars in an elderly globular cluster in the galaxy NGC 4472, about 50 million light-years from Earth. The existence of this small, elderly black hole puts an upper limit of 3 micrometers on the length of any extra dimension proposed by string theorists and particle physicists, a new study suggests.