The Beginning of Everything
The big bang—we’ve given a name to the beginning of time and space, but really it represents a lot of unanswered questions: how did the first stars and galaxies form, and how did the building blocks of everything—including humans—come to be? Knowing more about the universe’s beginning may help us to understand its future.
Astronomers have calculated that the universe is 13.8 billion years old. The Hubble Space Telescope has seen back to about 500 million years after the big bang, revealing galaxies with much less defined and more compact structures, very different than those close to us in space and time. With the James Webb Space Telescope, astronomers are looking back even farther, to the formation of the universe’s very first galaxies. By that point, gravity had already condensed gas into the first stars, which produced the first heavy elements, like carbon and oxygen. Within a few million years, the second generation of stars started forming from this enriched gas, and gravity began grouping them into the earliest galaxies. Webb will help us to understand the structure and composition of these first galaxies.
Over the next 13-plus billion years, more stars formed, extinguished, and dispersed their elemental material out into the universe. Galaxies grew in complexity and planetary systems formed around stars … until finally our star, the Sun, formed in an arm of a large spiral galaxy, and a system of planets, moons, and asteroids formed in its orbit. The third-closest planet, rich in water and with just the right amount of heat and light from the Sun, would become our home in the universe. From 1 million miles above the Earth, Webb looks back to the beginning.
How is Webb able to see back in time? Because light takes time to travel through space (a consistent 186,000 miles per second), there is a delay between when we see something and when it actually happened. In the small space of a room, the time for light to travel from the bulb to the corner is not noticeable. Between the Earth and the Moon, light takes 1.3 seconds, which means that we see the Moon as it was 1.3 seconds ago. Multiplied over the vast distances of the universe, light can take many, many years to reach us.
As ancient light from the first galaxies traveled through space, the expansion of the universe stretched the wavelengths beyond visible red to infrared, a process known as cosmological redshift. The Webb telescope was specifically designed to observe this light, which comes from some of oldest galaxies to take form. Studying these early objects will help to fill in some gaps in our knowledge: How did early stars and galaxies take shape? How do black holes figure into the formation of the early universe? What about the cosmic material that is undetectable, known as dark matter—is there evidence for it in the early eons of the universe? These are some of the perplexing and fascinating questions that astronomers can begin unraveling with Webb.