STAGES OF THE BIG BANG

Unit 4: Cosmology

REMINDER: THE UNIVERSE IS EXPANDING

RADIATION ERA

• From about 10⁻⁴³ s to 30,000 years after the Big Bang
• The expansion of the universe was dominated by radiation/high-speed particles
• This includes different wavelengths of electromagnetic waves
• Remnants of the radiation era exist in the current universe as cosmic microwave background radiation

DARK AGES

• From about 400,000 years until the first stars and galaxies emerged
• The universe had cooled enough to allow hydrogen to form
• Referred to as “dark” because there was no visible light – which means it cannot be viewed with a telescope

​

FIRST STARS

• Formed roughly 100 million years after the big bang in small protogalaxies
• The first stars were many times more massive than our sun
• Some stars exploded as supernovas, creating the first heavy elements
• The most massive stars collapsed into black holes

OLDEST STAR

• The oldest star, Earendel, was discovered in 2022 by the Hubble Space Telescope
• It has taken 12.9 billion years for it’s light to reach Each
• It is currently 28 billion light years away due to the universe’s expansion

FIRST GALAXIES

• Formed roughly 200 million years after the big bang
• Gravity pulled the protogalaxies together, forming galaxies

INTO THE PAST

• Time and space are Inseparable
• Light travels at a finite speed: 300,000 km/s (186,000 mi/s)
• A light year is defined as the distance that light travels in one earth year.
• When you look into the night sky, you look into the past
• The farther out you look, the farther back in time you see
• The sequence of events in the evolution of the universe are “written” in space like an eternal movie

​

INTO THE PAST

HUBBLE ULTRA DEEP FIELD

• An image from the Hubble Space Telescope that looks back 13 billion years 🡪 400 to 700 million years after the big bang
• Represents a narrow, deep look into the cosmos

​

HUBBLE DEEP FIELD

• An image from the Hubble Space Telescope that took 10 days to take and looks back to 1 billion years after the big bang

HUBBLE DEEP FIELD �(NOT PART OF THE NOTES)

The Hubble Space Telescope reached back 10 billion years to capture a view of young, never-before-seen galaxies in various stages of evolution.

​

The view shows the dimmest, most distant objects in the universe. Most are about 4 billion times fainter than can be seen by the human eye.

​

HUBBLE DEEP FIELD �(NOT PART OF THE NOTES)

Besides uncovering the classical spiral- and elliptical-shaped galaxies, Hubble found a bewildering assortment of other galaxy shapes and sizes that may yield important clues to the evolution of the universe.

​

Some of the galaxies may have formed less than 1 billion years after the Big Bang, the initial cosmic explosion that many scientists believe jump-started the universe.

​

HOW MANY OBJECTS ARE THERE?

• Each group will be assigned section A, B, or C from the Hubble deep field
• Within the group, students will be given a card with a portion of the image
• Count the number of “objects” in your individual card
• Record your count on the give index card

OBJECTS IN THE UNIVERSE

• Add together all the objects in your camera
• Add together the 3 cameras
• Multiply it by 3 x 10⁷
• Equals: objects in the universe

HOW BIG IS THE HUBBLE DEEP FIELD

HOW MANY GALAXIES ARE THERE?

ENTER…

James Webb Space Telescope

JWST

HUBBLE VS JWST

Hubble

• Visible and UV Light
• About the size of a large truck
• Orbits Earth
• Can see back roughly 1 billion years

JWST

• Visible and Infrared
• About the size of a tennis court
• Orbits the sun about 1.5 million km from Earth
• Can see back roughly 13.5 billion years

HUBBLE VS JAMES WEBB

IS JWST LIVING UP TO THE HYPE?

HUBBLE AND JWST SIDE-BY-SIDE