Stephen Hawking and Black Holes

• Stephen Hawking stated the Universe could have started from a singularity.
• Hawking likened the beginning of the Universe to the South Pole.
• According to Hawking, asking what happened before the Universe began is meaningless.
• In 1972, Hawking refined his black hole theories following a debate with Israeli physicist Jacob Bekenstein.
• Hawking's refined theories considered the laws of quantum mechanics, which deal with matter and energy behavior on the scale of atoms and subatomic particles.
• Quantum mechanics describes that pairs of particles and antiparticles are constantly meeting and annihilating each other throughout the Universe.
• Hawking calculated this occurs near the event horizon where the negatively charged particle falls into the black hole.
• The positively charged half streams away from the black hole's edge as radiation, known as Hawking radiation.
• Black holes lose energy and mass through black hole evaporation.
• Over eons, black holes continue to leak radiation and particles until they disappear in a final explosion.
• In 1974, Hawking published his calculation showing how the Universe began and how black holes evaporate.
• Hawking combined insights from the theory of the infinitely large (Einstein's general theory of relativity) and the theory of the infinitely small (quantum mechanics).
• Hawking produced a significant clue in modern physics' quest to find a single, unified "theory of everything" to explain the nature of the Universe.Hawking's discovery determined that black holes are not really black, but emit thermal radiation due to quantum effects.
• This was among the most important findings of 20th-century physics.
• Hawking's formula for Hawking radiation was initially rejected but has since become universally accepted.
• In 1979, Hawking was appointed Lucasian Professor of Mathematics at Cambridge University, a post he held until 2009.
• He continued to research black holes despite his disabilities.
• He received many accolades and high honors for his contributions to physics.
• Hawking wrote several popular science books, including A Brief History of Time, which was a runaway success.
• In his final years, he traveled widely, giving public lectures about his work.
• According to Stephen Hawking in 2008 "Black holes are stranger than anything dreamed up by science fiction writers, but they are firmly matters of science fact."
• Time, space, energy, and matter began from a single dense point of energy, a singularity.
• A Brief History of Time stayed on the Sunday Times bestseller list for 237 weeks.
• Hawking won the Breakthrough Prize in Fundamental Physics, worth $3 million.
• British mathematician and theoretical physicist Roger Penrose (1931-) is known for his work on black holes and the Big Bang theory.
• In the 1960s, Penrose was a reader and then professor in applied mathematics at Birkbeck College, London.
• In 1969, Penrose collaborated with Stephen Hawking to prove that black holes can arise from the gravitational collapse of massive stars.
• The paper by Penrose and Hawking was published by the Royal Society of London in 1970.
• Penrose also developed twistor theory, a key tool in quantum theory.
• Penrose created a way of mapping the regions of space-time around a black hole, know as Penrose diagrams.
• Penrose diagrams visualize the effect that gravity has on an object approaching a black hole.

Milestones

• Hawking wrote his PhD thesis, "Properties of expanding universes," in 1966, stating that the Universe started from a singularity.
• Hawking proved that gravitational singularities may exist while working with Roger Penrose in 1970.
• In 1974, Hawking made a key discovery, drawing on quantum theory to predict that black holes emit heat and eventually evaporate.
• Hawking became Cambridge's Lucasian Professor of Mathematics in 1979, a chair once held by Isaac Newton.
• He published A Brief History of Time in 1988, which became an instant hit.