What holds the galaxies together? Why is the universe still expanding from the Big Bang, and will it ever collapse again in a big crunch? Cosmologists-scientists who study the large-scale structure of the universe-ask these kinds of questions. Here are some answers they’ve come up with and some areas where they’re still in the dark.

The mysteries of gravity

Gravity is everywhere. It keeps our feet planted firmly on the ground, it holds the planets in orbit around the Sun and it keeps the stars and galaxies from flying apart. Basically, gravity holds the universe together. It’s also the most mysterious of nature’s forces.

The expanding universe

In 1929, astronomer Edwin Hubble discovered that other galaxies are racing away from our galaxy, the Milky Way. In fact, the farther away the galaxy is, the faster it’s receding.

Dark matter and the fate of the universe

Only 10 per cent of the universe radiates light, the other 90 per cent is invisible to us. This "dark matter" is vital to our understanding of the fate of the universe. Without enough dark matter to put on the "gravitational brakes," cosmic expansion will continue thinning out the universe forever.
Canadian Heritage Information Network
Australian Museums & Galleries Online, Australia; Centre of the Universe; Gemini Observatory, Hawaii; Glenbow Museum; The Manitoba Museum; National Research Council Canada; Planétarium de Montréal

© Canadian Heritage Information Network, 2003

Teachers' Centre Home Page | Find Learning Resources & Lesson Plans