Metric expansion of space

High school (ages 12+)
Space & Astronomy

Name:

Date:

Step 1 · Read the article

Open the article and read it at the level above. Then answer the questions below in your own words.

https://smallwhale.org/articles/metric-expansion-of-space

Write what each word means, using the article.

Do not copy the article. Write two things you learned, the way you would explain them to a friend.

Answers below are taken from the article’s stored facts, so they match what the student read.

1. What is metric expansion of space?Metric expansion of space means the universe is getting bigger, stretching the distances between objects that aren't held together by gravity. Imagine a balloon with a grid on it; as the balloon inflates, the grid lines stretch and the points on the grid move farther apart.
2. Why do we see galaxies moving away from us?We see galaxies moving away because space itself is stretching. As the light travels through this expanding space, its wavelength gets longer, which makes the light look redder—a phenomenon called cosmological redshift.

Cosmological Redshift: The stretching of light wavelengths due to the expansion of spacetime itself as photons travel across vast cosmic distances.
Friedmann Equations: A set of equations in cosmology that describe the expansion of a homogeneous and isotropic universe based on general relativity.
Dark Energy: A hypothetical form of energy believed to be responsible for the observed accelerated expansion of the universe.