PHY 102 EXAM SCRIPT 2025/2026 QUESTIONS AND
SOLUTIONS MARKED A+
✔✔Scientific theory - ✔✔A well-substantiated explanation of some aspect of the natural
world, based on a body of facts that have been repeatedly confirmed through
observation and experiment.
✔✔Young cosmos - ✔✔Unfathomably hot and dense and so hot nuclei couldn't stay
together. It is space and time and begins to expand.
✔✔Universe began - ✔✔Approximately 13.8 billion years ago based on The Big Bang
Theory. The Bang = a universe in initial singularity.
✔✔Quarks - ✔✔Basics particles that cannot be subdivided any more.
✔✔Big Bang Theory - ✔✔The leading cosmological theory of how our Universe started
from a high temperature, high density state and expanded.
Birth of the Universe
13.82 billion years ago
✔✔Hubble - ✔✔Observational evidence that galactic redshifts were linearly and directly
proportional to the distance from Earth. Hubble's Law which has a graph. Y axis =
recession speed of galaxies and X axis = distance from Earth. Key term is he
EXPERIMENTALLY first discovered the redshift and distance relationship and implies
the universe is expanding.
✔✔Gamow - ✔✔First discovered primordial abundance of elements. 75% Hydrogen
and 25% Helium by mass. He predicted CMBR would exist with radiation of around 5 K.
✔✔Hoyle - ✔✔Coined the name "Big Bang Theory" from Lemaitre's "Primeval Atom
Theory" because he did not believe in the theory. Discovered stars could create
elements. STELLAR NUCLEOSYNTHESIS! Supernovae create the heavier/rarer
elements like Uranium or Gold.
✔✔Lemaitre - ✔✔Belgian, Roman Catholic Priest, first to propose "Primeval Atom
Theory" which is also known as "Cosmic Egg" theory that the universe started at a
singular point and expanded.
✔✔Slipher - ✔✔First to measure redshifts of spiral nebula (which were actually
galaxies). Found that spiral nubulae had redshifts in their spectra.
✔✔Supernova explosion - ✔✔Explosion of a star
, ✔✔Stellar nucleosynthesis - ✔✔The process by which elements are created within stars
✔✔Robert Dicke - ✔✔Princeton professor who didn't build a microwave radio detector
in time to find CMBR.
✔✔Amo Penzias & Robert Wilson - ✔✔Discovered CMBR on accident and won the
Nobel Prize.
✔✔COBE - ✔✔Cosmic Background Explorer. First space satellite to study the CMBR. It
was launche in 1989.
✔✔Smoot & Mather - ✔✔Use COBE data to show anisotropy and win a Nobel Prize in
1993.
✔✔WMAP - ✔✔Wilkerson Microwave Anisotropy Probe is launched in 2001 to study
CMBR and shows where gravity formed stars and galaxies indicated by the blue/hot
areas.
✔✔Four fundamental forces - ✔✔Gravity, strong, weak, and electromagnetic.
✔✔Gravity - ✔✔An attractive force between objects with mass; it is the weakest force
but its range (or reach) is infinite.
✔✔Electromagentic - ✔✔The electric force that exists between charged objects that can
be attractive (balloon sticking to a wall) or repulsive; the magnetic force exists between
magnets and can be attractive or repulsive. 2 north poles will repel one another; 1 south
pole and 1 north pole will attract one another.
✔✔Weak - ✔✔This force is in the nucleus of atoms and controls radioactive decay of
the nucleus. Radioactive decay is when a nucleus undergoes changes and becomes a
new nucleus of a different element.
✔✔Strong - ✔✔This is the force that holds protons together in the nucleus of an atom; it
is the strongest force, but it's range (or reach is very short)
✔✔Planck epoch - ✔✔the first epoch, and is the epoch we know littlest about. There
was one force called the "Superforce" instead of the four we have now. Need to unify
quantum mechanics and gravitation into one theory.
✔✔GUT epoch - ✔✔Grand Unified Theory...gravity separates from the "Superforce" and
three of the four forces are unified as the GUT force. Elementary particles come into
existence.
SOLUTIONS MARKED A+
✔✔Scientific theory - ✔✔A well-substantiated explanation of some aspect of the natural
world, based on a body of facts that have been repeatedly confirmed through
observation and experiment.
✔✔Young cosmos - ✔✔Unfathomably hot and dense and so hot nuclei couldn't stay
together. It is space and time and begins to expand.
✔✔Universe began - ✔✔Approximately 13.8 billion years ago based on The Big Bang
Theory. The Bang = a universe in initial singularity.
✔✔Quarks - ✔✔Basics particles that cannot be subdivided any more.
✔✔Big Bang Theory - ✔✔The leading cosmological theory of how our Universe started
from a high temperature, high density state and expanded.
Birth of the Universe
13.82 billion years ago
✔✔Hubble - ✔✔Observational evidence that galactic redshifts were linearly and directly
proportional to the distance from Earth. Hubble's Law which has a graph. Y axis =
recession speed of galaxies and X axis = distance from Earth. Key term is he
EXPERIMENTALLY first discovered the redshift and distance relationship and implies
the universe is expanding.
✔✔Gamow - ✔✔First discovered primordial abundance of elements. 75% Hydrogen
and 25% Helium by mass. He predicted CMBR would exist with radiation of around 5 K.
✔✔Hoyle - ✔✔Coined the name "Big Bang Theory" from Lemaitre's "Primeval Atom
Theory" because he did not believe in the theory. Discovered stars could create
elements. STELLAR NUCLEOSYNTHESIS! Supernovae create the heavier/rarer
elements like Uranium or Gold.
✔✔Lemaitre - ✔✔Belgian, Roman Catholic Priest, first to propose "Primeval Atom
Theory" which is also known as "Cosmic Egg" theory that the universe started at a
singular point and expanded.
✔✔Slipher - ✔✔First to measure redshifts of spiral nebula (which were actually
galaxies). Found that spiral nubulae had redshifts in their spectra.
✔✔Supernova explosion - ✔✔Explosion of a star
, ✔✔Stellar nucleosynthesis - ✔✔The process by which elements are created within stars
✔✔Robert Dicke - ✔✔Princeton professor who didn't build a microwave radio detector
in time to find CMBR.
✔✔Amo Penzias & Robert Wilson - ✔✔Discovered CMBR on accident and won the
Nobel Prize.
✔✔COBE - ✔✔Cosmic Background Explorer. First space satellite to study the CMBR. It
was launche in 1989.
✔✔Smoot & Mather - ✔✔Use COBE data to show anisotropy and win a Nobel Prize in
1993.
✔✔WMAP - ✔✔Wilkerson Microwave Anisotropy Probe is launched in 2001 to study
CMBR and shows where gravity formed stars and galaxies indicated by the blue/hot
areas.
✔✔Four fundamental forces - ✔✔Gravity, strong, weak, and electromagnetic.
✔✔Gravity - ✔✔An attractive force between objects with mass; it is the weakest force
but its range (or reach) is infinite.
✔✔Electromagentic - ✔✔The electric force that exists between charged objects that can
be attractive (balloon sticking to a wall) or repulsive; the magnetic force exists between
magnets and can be attractive or repulsive. 2 north poles will repel one another; 1 south
pole and 1 north pole will attract one another.
✔✔Weak - ✔✔This force is in the nucleus of atoms and controls radioactive decay of
the nucleus. Radioactive decay is when a nucleus undergoes changes and becomes a
new nucleus of a different element.
✔✔Strong - ✔✔This is the force that holds protons together in the nucleus of an atom; it
is the strongest force, but it's range (or reach is very short)
✔✔Planck epoch - ✔✔the first epoch, and is the epoch we know littlest about. There
was one force called the "Superforce" instead of the four we have now. Need to unify
quantum mechanics and gravitation into one theory.
✔✔GUT epoch - ✔✔Grand Unified Theory...gravity separates from the "Superforce" and
three of the four forces are unified as the GUT force. Elementary particles come into
existence.
