Transcript Black Hole
Black Hole Special Relativity • Einstein’s special theory of relativity has two parts. – All objects moving at constant velocity have the same laws of physics – The speed of light is constant for all observers The pendulum will swing at the same rate if the car is moving or not. General Relativity • If nothing travels faster than light, how does gravity affect objects? • General relativity showed that acceleration acts just like gravity on objects. On Earth, with gravity, objects in the rocket have 1 g pulling down. In space, with no gravity, the engines can create a thrust of 1 g pulling to the floor. Bending Light • Photons, which transmit light, are massless. – Photon energy has an equivalent mass – Photons affected by gravity, which bends the light • We picture space as curved by gravity, and light follows the curves like a lens. Pure Gravity • In a neutron star, degenerate neutrons resist gravity. • For Mns greater than 3 M the neutron star collapses. • There is nothing left to oppose gravity and the mass collapses to an infinitesimal point. Trapped Light • The gravitational force increases as the distance decreases. – Escape velocity also increases – Escape velocity can exceed the speed of light – No light or matter escapes • This is called a black hole. Photon deflected Photon trapped Observing Radiation • Matter which reaches the event horizon is trapped. • The acceleration causes radiation before matter is lost. – All parts of spectrum Black Hole Mass • Black holes can keep accumulating mass. – Stars orbit around according to Kepler’s laws – Measure orbit and calculate mass • Some black holes have the mass of over a million suns.