Timeline of the Universe (Earth & Space)

Lesson notes

Overview

From the Big Bang to the present: expansion, cooling and the formation of structure. This topic is rated intermediate and is number 44 of 98 in Earth & Space. Builds on the basics with relationships, methods and trade-offs.

What you are seeing

The panel above shows the steps of a process, laid out in order. Click a step to see what happens next. The animation is drawn live from the model, so everything you see responds to the sliders. Press Space to pause, use Restart to replay from the start, and change the speed to slow down quick events.

In depth

In the Big Bang model, the universe started about 13.8 billion years ago in a hot, dense state and has been expanding and cooling since. In the first seconds the forces separated and quarks formed protons and neutrons; after three minutes light nuclei formed; after 380,000 years atoms formed and the cosmic microwave background was released; the first stars appeared within a few hundred million years, then galaxies. Our solar system formed 4.6 billion years ago.

Reading the relationship

The expression "13.8 billion years" is a compact summary of the idea. It uses the symbols b, i, l, o, n, y; name what each one stands for before you start. Then use the sliders to see how changing one quantity changes the others.

A guided exploration

1. Run the animation once with the default settings and describe in words what happens. 2. Change one slider at a time and note which quantity responds most. 3. Push each slider to its extreme and decide whether the result still makes sense.

Try this

Predict the outcome first, then test extreme slider values to find where the pattern changes or breaks.

Common pitfalls

Earth and space systems work on very different scales of time and distance. Check which scale a number refers to before comparing it with another.

How it connects

It builds on “Cosmological Redshift”, the topic before it in Earth & Space. Once you are comfortable, continue with “How Gravity Assists Work”.

Why it matters

Earth and space science helps us understand our planet, its climate and the wider universe.

Where you might use it

Revising “Timeline of the Universe” before a class, exam or certification
Forecasting weather and understanding climate records and their uncertainty
Planning for earthquakes, floods and other natural hazards in cities
Interpreting satellite images, space missions and the age of rocks and stars

Frequently asked questions

What is Timeline of the Universe?

From the Big Bang to the present: expansion, cooling and the formation of structure. It is an intermediate topic in Earth & Space.

How do I use the Timeline of the Universe simulation?

The panel at the top shows the steps of a process, laid out in order. Click a step to see what happens next. Move the sliders one at a time, then press Space to pause the animation and look closer.

What does the formula mean?

The expression 13.8 billion years packs the idea into symbols. Name each symbol first, then change one quantity with the sliders and see which others respond.

Who is this topic for?

Builds on the basics with relationships, methods and trade-offs. If the quiz feels hard, reread the lesson notes and try the previous topic first.

What should I learn before this?

Start with “Cosmological Redshift”, the previous topic in Earth & Space. Each topic in a subject builds on the ones before it.

How do I track my progress?

Press “Mark as learned” on this page. Progress is stored only in this browser and is never sent anywhere. The Browse page can show topics you have learned or still need to learn.