Cosmic Microwave Background Radiation

Lab Brief #5

🎯 Your mission

Learn the rule. Then catch nature using it.

⚡ The twist

Gravity is invisible — but it shapes everything.

What you'll learn

The universe is filled with faint microwave radiation, almost identical in every direction, left over from about 380,000 years after the Big Bang when it first became transparent. Its temperature of 2.7 K and its tiny ripples match the model's predictions closely.

Key words

cosmic microwave background
Faint microwave radiation left over from the early universe.
kelvin
The SI temperature unit; 0 K is absolute zero, and 2.7 K is the background temperature.

Make a hypothesis first

Before you check: which is closer?

Say your guess out loud — then find out if you were right.

Step 1 of 4 · Read

Think about what you just learned: say what "cosmic microwave background" and "kelvin" mean in your own words before you start.

Step 2 of 4 · Do

Research the 1965 Penzias and Wilson discovery and write a short account of how they ruled out equipment faults, including the pigeons. Identify what made the signal impossible to explain locally.

Step 3 of 4 · Observe

Record what actually happened, including anything that did not match what you expected.

Step 4 of 4 · Record

Write a conclusion that answers the question this lesson opened with, and state your uncertainty.

Question 1 of 2

The cosmic microwave background has a temperature of about:

How sure are you?😐 maybe

Question 2 of 2

The background radiation is evidence that the early universe was:

How sure are you?😐 maybe

Mind = blown

🌟 The light from the closest star (after the sun) takes 4 years to reach you.

Nice work!

You got 0 of 2 right.

Next: The Speed of Light as a Limit All lessons

🎯

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✨ More to explore

🌍 Where you see this in real life: Every sunrise and every shadow is this idea in action.

🏆 Stretch challenge (try it this week): Look at the moon tonight. Notice its shape. Look again in 3 days.

👨‍👩‍👧 For the dinner table: “If you could visit any planet, which would you pick and why?”

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