Black holes are regions of extreme gravity from which nothing, not even light, can escape. They form from the collapse of very massive stars over 3 solar masses. Black holes come in different types depending on their charge and rotation. They contain a central singularity of infinite density and an event horizon boundary. Near a black hole, time dilates such that time slows greatly and stops at the event horizon. Black holes also emit Hawking radiation over time by emitting virtual particle pairs, causing them to lose mass.

1. BLACK HOLES

2. INTRODUCTION
• A black holes is a region in space-time with extreme gravity such that nothing can
escape it (including electromagnetic waves such as light)
• First predicted by the General Theory of Relativity

3. TYPES OF BLACK HOLE
• The Schwarzchild black hole
• Has no electric charge or rotation
• The Reissner-Nordstrom black hole
• Does not rotate but has electric charge
• The Kerr-Newman black hole
• Has electric charge and rotates
• The Kerr black hole
• Rotates but no electric charge

4. FORMATION
• Black holes are formed from the death of stars
• White dwarf
• M < 1.4 M ☉
• Electron Degeneracy pressure
• Neutron star
• 1.4 M ☉ < M < 3 M ☉
• Neutron Degeneracy pressure
• Black holes
• M > 3 M ☉

5. STRUCTURE
• Event horizon
• Point of no return
• Singularity
• Centre of black hole
• Infinite density and infinitely small
• All laws of physics breaks down
• The Accretion disk
• Disk of stellar material around the black hole
• Photon sphere
• Region in which photons are forced to orbit the black hole

6. TIME DILATION
• Black holes distort space and time
• Time slows down near a black hole
• The closer to the event horizon, the slower the time runs
• For a non rotating black hole, 𝑡0 = 𝑡𝑓 1 −
𝑟𝑠
𝑟
, 𝑟𝑠 = Schwarzchild radius
• Time stops at the event horizon relative to an outside observer. Therefore, objected
tend to “freeze” when they enter the event horizon

7. HAWKING RADIATION
• Virtual particles forms in empty space
• When near the event horizon, one particle
may enter the blackhole
• The other particle escapes, known as the
hawking radiation
• Resulting in the black hole losing mass and
energy over time