Scientists want to use the James Webb Space Telescope to track the origin of the universe

Everyone knows that telescopes are used to see distant objects. But when scientists talk about using a telescope to look in the past, especially the moments immediately after the formation of the universe as we know it, it’s perplexing. The team behind the most powerful telescope in the world, the James Webb Space Telescope (JWST), is trying to do exactly that. One of the foremost goals of the JWST is to observe the formation of the first stars and the first galaxies immediately after the Big Bang.

To be clear, looking into the past is something that astronomers do regularly and not something that’s specific to only the JWST. When scientists and astronomers observe distant cosmic objects, the information that they are receiving is millions, even billions of years old. How is that possible? It’s a simple principle that light only has a finite speed and when traversing through vast distances of space, it takes the light a considerable amount of time to reach from one point to the next.

Consider the Sun. We see it every day for hours at a time. But whenever we’re looking up in the sky to see the Sun, we’re actually seeing it as it was about 8 minutes previously because that’s how long it takes sunlight to reach Earth. If the Sun was to suddenly vanish, then we would not see that happen in the sky until after 8 minutes had passed. With most distances across the universe measured in millions and billions of light years, we are actually observing those objects as they were millions and billions of years in the past.