Fred Hoyle & Katherine Johnson: Astrophysicists

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Fred Hoyle (1915–2001)

• A British astrophysicist who worked on the origin of elements in stars.
• Postulated that nuclear reactions within large stars create most chemical elements step-by-step.
• He was a proponent of the steady state theory, which suggests the Universe maintains constant average density through continuous creation of new matter as it expands.
• He coined the term "Big Bang" disparagingly during a radio talk about the rival theory.
• His steady state theory was largely discredited in the 1960s.
• He later focused on the presence of organic molecules in comets, believing they brought life to Earth.

Katherine Johnson (1918–)

• An award-winning American mathematician who was key in calculating trajectories for space missions, including Alan Shepard's.
• She began at NACA in 1953, manually performing calculations for engineers.
• She aided in planning the launch site and flight path for the Apollo 11 Moon mission in 1969.
• She later worked on the US space shuttle program and retired from NASA in 1986.

Irene Uchida (1917–2013)

• A Canadian medical geneticist who initiated work on how genes and chromosomes affect health.
• She investigated chromosome differences in genetic conditions and congenital abnormalities.
• These conditions were congenital heart disease and Down syndrome, where individuals have an extra chromosome.
• She examined the effects of X-rays on chromosomes.

Yvonne Brill (1924–2013)

• Born near Winnipeg, Canada, and started with Douglas Aircraft in 1945.
• She invented a propulsion system to maintain unmanned spacecraft in stationary orbit.
• She also worked on thrusters for weather satellites, rocket designs for US Moon missions, and the Mars observer.
• While at NASA from 1981-1983, she worked on a rocket engine for the space shuttle.

Abdus Salam (1926–1996)

• Born in Pakistan, he studied mathematics and physics at the University of Cambridge, UK.
• He proposed the electroweak theory, explaining the weak interaction between subatomic particles and its potential unification with the electromagnetic force.
• His theory posited messenger particles for the weak interaction, with different messengers exchanged in different instances.
• His theories were proven correct at CERN in 1973.
• He was jointly awarded the Nobel Prize in Physics with Sheldon Lee Glashow and Steven Weinberg in 1979.

Vera Rubin (1928–2016)

• During the 1970s, she discovered that stars in the outer spiral galaxy orbit as fast as those closer to the center.
• This contradicted Newton's laws of gravity and indicated galaxies have a halo of invisible matter affecting outer stars.
• In 1970, Rubin confirmed this in the Andromeda Galaxy.
• By 1985, she had examined 60 spiral galaxies and found it was a general phenomenon.
• Rubin's work convinced astronomers of the existence of dark matter.
• She received the National Medal of Science in 1993.

Peter Higgs (1929–)

• Born in Newcastle, England, studied physics at King's College London.
• He began at the University of Edinburgh in 1960.
• He is best known for his theory explaining the origin of the mass of elementary particles.
• According to this theory, particles gain mass by interacting with the Higgs field that permeates space.
• He predicted the Higgs field would produce the Higgs boson particle.
• The search for the Higgs boson led to the Large Hadron Collider (LHC) at CERN.
• Scientists discovered a particle with the predicted Higgs boson characteristics in 2012.
• Received the Nobel Prize in Physics in 2013 with François Englert for their 1964 work.

Eric Kandel (1929–)

• He fled Vienna with his family to the US due to anti-Semitism.
• He studied medicine at New York University and received his degree in 1956.
• Interested in the cellular basis of behavior.
• He was awarded the Nobel Prize in Physiology or Medicine in 2000 for his work on synapses in memory and learning.
• He investigated sea slugs to clarify short- and long-term memory processes.
• He showed that the memory processes are equally applicable in humans.

Mario J. Molina (1943–)

• Born in Mexico City, he studied chemical engineering.
• In 1974, he and Sherwood Rowland demonstrated that CFCs from aerosols, foams, and refrigerants destroy the ozone layer.
• This work led to banning/limiting CFCs and earned Molina and Rowland the 1995 Nobel Prize in Chemistry.

Lap-Chee Tsui (1950–)

• A Canadian medical geneticist born in Shanghai, moved to Canada in 1977.
• He jointly discovered the faulty gene responsible for cystic fibrosis which causes thick mucus.
• Identifying the gene paved the way for treatments based on gene correction or replacement.

Mae Carol Jemison (1956–)

• The first African American woman to travel in space, she went into orbit in the space shuttle Endeavour in 1992.
• Jemison graduated from medical school in 1981 and served as a medical officer with the Peace Corps in West Africa.
• In 1985, she applied to the US space agency, and in 1987, became one of 15 candidates selected from over 2,000 applicants to train as an astronaut.
• She was the science mission specialist on the space shuttle and a coinvestigator of two bone cell research experiments performed there.

Donna Strickland (1959–)

• A Canadian optical physicist who paved the way for the shortest and most intense laser pulses.
• In 1985, she and Gérard Mourou developed chirped pulse amplification (CPA).
• She and Mourou were jointly awarded the Nobel Prize in Physics in 2018 for CPA..
• Strickland became an associate professor at the University of Waterloo in 1997, leading the ultrafast laser research team.
• CPA has uses in laser eye surgery and some cancer therapies.

Carol Greider (1961–)

• An American molecular biologist.
• She has researched telomeres and the enzyme telomerase.
• Telomeres are DNA segments at the ends of chromosomes, important for cell life span.
• In 2009, she, Elizabeth Blackburn, and Jack W. Szostak were awarded the Nobel Prize in Physiology or Medicine.
• Her work found that inhibiting telomerase in cancer cells slows tumor growth, making it a potential anticancer drug development.

Explore the contributions of Fred Hoyle and Katherine Johnson to astrophysics. Hoyle worked on the origin of elements in stars and proposed the steady state theory. Johnson calculated trajectories for space missions, including Alan Shepard's.