PS1 Unit 1 Study Guide - The Universe

Vocabulary flashcards based on Unit 1 study material covering fundamental terms, physical forces, cosmological timeline, and key evidence supporting the Big Bang theory.

Matter

The physical "Lego bricks" that take up space and have mass, but cannot move on their own.

Forces

The invisible "managers" that tell physical stuff how to move and interact.

Energy

The fuel or "currency" spent to make physical stuff move or change.

Motion

A change in position measured against a reference point.

Strong Nuclear Force

The ultimate "glue" that holds protons together inside an atom's nucleus, acting with an incredibly strong strength over an incredibly small range.

Electromagnetic Force

The force that causes like charges to repel and opposite charges to attract, acting as the "cosmic architect" by binding negative electrons to positive nuclei.

Gravity

The "Cosmic Sculptor" that pulls massive, cold gas clouds together until they ignite into stars, shaping only the largest "stuff" in the universe with an incredibly weak strength and infinite range.

Law of Conservation of Energy and Matter

The principle stating that matter and energy cannot be created or destroyed, meaning the total amount of matter and energy in the universe never changes.

Fundamental Forces Comparison

A comparative guide showing that Strong Nuclear Force holds protons, neutrons, and nuclei; Electromagnetic Force holds atoms, solids, and liquids; and Gravity holds planets, stars, and galaxies.

Timeline of the Universe

The chronological progression from the Big Bang ($0\text{ seconds}$), particle formation ($1\text{ microsecond}$), nuclei ($3\text{ minutes}$), neutral atoms ($380,000\text{ years}$), stars ($200\text{ million years}$), to present day ($13.8\text{ billion years}$).

Light Wavelength Shift

The shift in light wavelengths where blue light indicates an object moving towards an observer, and red light indicates an object moving away.

Redshift

An observation that light from distant galaxies was stretched towards the red end of the light spectrum (analogous to a stretched rubber band), concluding that all galaxies are expanding outward from a single point.

Abundance Ratio

The "recipe" of the universe observing that the early universe was composed of $\sim 75\%$ Hydrogen and $\sim 25\%$ Helium, matching calculations from Big Bang scientists about expected element proportions.

CMBR (Cosmic Echo)

Cosmic Microwave Background Radiation, observed as a faint background hum coming from everywhere in the universe (analogous to radio static), concluded to be energy left over from a huge explosion in the early universe.