A cosmic time machine: how the James Webb Space Telescope lets us see the first galaxies in the universe
It has been an exciting week with the release of breathtaking photos of our Universe by the James Webb Space Telescope (JWST). Images such as the one below give us a chance to see faint distant galaxies as they were more than 13 billion years ago.
It’s the perfect time to step back and appreciate our first-class ticket to the depths of the Universe and how these images allow us to look back in time.
These images also raise interesting points about how the expansion of the Universe factors into the way we calculate distances at a cosmological scale.
Modern time travel
Looking back in time might sound like a strange concept, but it’s what space researchers do every single day.
Our Universe is bound by the rules of physics, with one of the best-known “rules” being the speed of light. And when we talk about “light”, we’re actually referring to all the wavelengths across the electromagnetic spectrum, which travel at around a whooping 300,000 kilometres per second.
Light travels so fast that in our everyday lives it appears to be instantaneous. Even at these break-neck speeds, it still takes some time to travel anywhere across the cosmos.
When you look at the Moon, you actually see it as it was 1.3 seconds ago. It’s only a tiny peek back in time, but it’s still the past. It’s the same with sunlight, except the photons (light particles) emitted from the Sun’s surface travel just over eight minutes before they finally reach Earth.
Our galaxy, the Milky Way, spans 100,000 light-years. And the beautiful newborn stars seen in JWST’s Carina Nebula image are 7,500 light-years away. In other words, this nebula as pictured is from a time roughly 2,000 years earlier than when the first ever writing is thought to have been invented in ancient
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