Scientists looked further into the cosmos and, while still being on Earth, captured the first light of the universe billions of years away using one of the most powerful telescopes on Earth. The light is the only reason why we are able to see things in the universe. From the most mundane thing to the hardest things to observe in the cosmos, it is only visible because light travels to our optics and makes something observable — if there weren’t any, we would be in total darkness, like the universe before the Big Bang.
Light is extremely important in human existence
The light-speed concept is directly connected to how humans can see anything. The time it takes for light coming from a point A to reach point B is almost undetectable in the daily routine, but photons travel really fast, and it actually takes a couple of milliseconds to get there — the actual speed of light in a vacuum is 299,792,458 meters per second.
According to the laws of physics, if humans could travel at the speed of light, they would be able to reach further away in the cosmos, but they could never come back to the current conditions because of spacetime dilation. To see further into the universe, it is not necessary to leave the Earth, as telescopes on the ground and in orbit have been doing the hard work for decades. With that in mind, the Atacama Cosmology Telescope (ACT) just registered the first light.
First light of the universe captured by the ACT
The telescope in Chile, located in the Atacama Desert, registered the first light in the universe in the early stages after its formation, when it was around 380,000 years old. The research revealed movements and polarization of cosmic light with clarity as it has traveled over 13 billion years to reach the telescope in South America. What is possible to observe in the image is the detailed movement of the hydrogen and helium, the most abundant chemicals in the universe.
The director of the Atacama Cosmology Telescope, Suzanne Staggs, said that scientists are learning how hydrogen and helium are moving, and through this, they are able to track the movements of the light polarization to understand how strong the gravitational pull was in different parts of the cosmos a long time ago.
After the Big Bang, the plasma that filled the universe in the early stages of life was too hot for light to propagate freely. Now, with the new images, scientists have a clear view of the subtle variations in the density and velocity of the gases in the universe at the time, which helps to answer old questions about the origin of the universe. Another researcher from the project, Sigurd Naes, stated that by observing the chemical elements in the first light, future studies will be able to piece together the evolution of the cosmos.
We can’t look further than the first light
Even with the discovery of the first light of the universe, scientists cannot look all the way back to the Big Bang, when it was just an opaque fog of ionized plasma, impossible for light to penetrate, which caused photons to be scattered off free electrons. But when these free particles hid in atoms, light was able to propagate.
On the other hand, the biggest cosmological question remains unanswered: the Hubble constant. This theory was created by Edwin Hubble after discovering that the universe is in constant expansion, which became a fundamental law in cosmology. Hubble found out that an invisible force is responsible for the expansion of the universe, and named it dark energy. Decades later, an astronomer from the University of Chicago created the “dark matter”.