The Early Universe
This fundamental theory describes the origin and evolution of the universe from an extremely hot, dense state.
What is the Big Bang theory?
This astronomer's observations of redshift in distant galaxies provided key evidence for the expansion of the universe.
Who is Edwin Hubble?
This type of spectrum shows all wavelengths of light, produced by a hot, dense object.
What is a continuous spectrum?
On the HR diagram, the majority of stars, including our Sun, are found in this broad band.
What is the Main Sequence?
Early experiments with these glowing streams in evacuated tubes led to the discovery of the electron.
What are cathode rays?
Before the Big Bang, all matter and energy in the universe was concentrated into an infinitesimally small, hot, and dense point known as this.
What is a singularity?
The phenomenon where light from receding objects shifts to longer wavelengths is known as this
What is Redshift?
When light from a continuous source passes through a cool gas, this type of spectrum with dark lines is produced.
What is an absorption spectrum?
A star's color is a direct indicator of this characteristic.
What is surface temperature?
J.J. Thomson's experiment determined this fundamental property of the electron.
What is its charge-to-mass ratio?
The Big Bang theory predicts that the universe is not static but has been doing this ever since its beginning.
What is expanding?
Einstein's famous equation,
E=mc^2
describes the equivalence of these two fundamental quantities.
What are energy and mass?
Hot, thin gases produce this type of spectrum, characterized by bright lines at specific wavelengths.
What is an emission spectrum?
In more massive stars, this cycle, involving carbon, nitrogen, and oxygen as catalysts, fuses hydrogen into helium.
What is the CNO cycle?
Robert Millikan's famous experiment, using charged droplets, precisely measured this fundamental quantity of the electron.
What is its charge?
The relative abundance of these two lightest elements in the universe, formed during Big Bang nucleosynthesis, is a key piece of evidence for the theory.
What are hydrogen and helium?
This type of nuclear reaction, fusing lighter nuclei into heavier ones, powers stars.
What is nuclear fusion?
Stellar spectra are primarily used to determine a star's surface temperature and this other key characteristic.
What is chemical composition?
After exhausting hydrogen in their cores, Main Sequence stars evolve into this phase, becoming much larger and redder.
What are red giants?
This experiment, involving alpha particles scattering off a thin gold foil, led to the nuclear model of the atom.
What is the Geiger-Marsden experiment?
This "echo" of the Big Bang, discovered in 1964, provides compelling evidence for the universe's hot, dense early state.
What is the Cosmic Microwave Background (CMB)?
In stars less massive than the Sun, this chain reaction is the primary source of energy, turning hydrogen into helium.
What is the proton-proton chain?
This diagram plots a star's luminosity against its surface temperature, aiding in stellar classification.
What is the Hertzsprung-Russell (HR) diagram?
The ultimate fate of a low-mass star like the Sun after shedding its outer layers.
What is a white dwarf?
James Chadwick's discovery of this neutral subatomic particle explained the missing mass in atomic nuclei.
What is the neutron?