Science Common Sense

112 - How do we know the age of the universe?

We know the age of the universe by using special methods to look back in time. Here are a few ways:

1. Looking at the light from distant stars: Some stars are very far away. We can see how long it took for their light to reach us. Since light travels at a known speed, we can calculate how long ago they were shining.
2. Measuring the expansion of the universe: The universe is still growing. By looking at how fast galaxies move away from each other, scientists can rewind time and figure out when everything started. It's like watching a video in reverse.
3. Studying the oldest things we can find: Rocks and meteorites can tell us about the early universe. Scientists can date these objects using special techniques, which give us clues about how old they are.
4. Using special cameras and spacecraft: Spacecraft like the Hubble Telescope and satellites have looked back in time to see the universe when it was much younger. These observations help scientists calculate the universe's age.

By combining all these methods, scientists have agreed that the universe is about 13.8 billion years old.