Cosmic Dawn Introduction (01:50)
The real moment of creation came 100 million years after the Big Bang, when the first stars were born. Astronomers are trying to witness and understand this moment.
Emu in the Sky (02:44)
In Western Australia, Aboriginal people use the Milky Way as an indication of when to hunt. Astronomer Steven Tingay has built a radio telescope to study the first stars.
Universe's Dark Ages (03:40)
Harvard astronomer Avi Loeb looks at a cosmic photo album with images of the universe in its infancy. After the Big Bang, it became cooler and darker as it expanded. The Big Bang created space and time for the creation of light.
Search for Ancient Stars (03:22)
Astronomers hope to fill in the gap in cosmic history. At Siding Springs Observatory, Stefan Keller looks for stars that have survived since the cosmic dawn. Their composition reveals their age.
Determining Star Ages (03:27)
Stars have created all elements on Earth. When they run out of fuel, many explode in supernovas: debris is recycled into the next generation of stars. Each new generation has increased iron concentrations. Keller's telescope looks for bluer stars indicating low iron content.
Oldest Star in the Universe (04:06)
In 2013, Keller's telescope discovered a star with low iron content. A light spectrum shows no detectable iron amounts; it was made early in the stellar recycling process and has burned for 13.6 billion years. It is among the second generation of stars after the dark ages.
Building the First Stars (03:12)
During the dark ages, the universe contained diffuse, single hydrogen atoms. Volker Bromm uses a super computer to model how stars were constructed.
Cosmic Dawn Stalemate (03:02)
Bromm explains the theory that gravity condensed hydrogen atoms, eventually triggering nuclear fusion. However, models showed that random motion heated gas, pushing outward.
Recreating the First Star (02:40)
Hydrogen molecules absorb heat. This process overcame the stalemate between gravity and gas, allowing the first stars to form. Without elements, they were massive.
First Star Light (02:05)
After 100 million years, the dark ages ended. The first stars were 30 times hotter than the sun and shined ultraviolet blue. Bromm patches a computer image into a cosmic photo album.
Imagining the Cosmic Dawn (03:25)
After the dark ages, star formation accelerated across the universe. Early stars created heavy elements necessary for life, burned fuel quickly, and had short life spans.
Opaque Universe (03:06)
The first stars died in hypernovas, dispersing elements that formed subsequent generations. Hydrogen fog prevented light from traveling.
Transition to Transparency (03:46)
Abel uses a super computer simulation to model how the universe went from opaque to transparent. Early giant stars emitted ultraviolet light that ionized hydrogen gas around them— a phenomenon likened to Swiss cheese. View a model of the universe during the reionization process.
Radio Hydrogen (03:48)
Hear a summary of the cosmic dawn theory. The first stars left behind "ghosts," bubbles in the hydrogen fog that transmitted a radio signal. Astronomers build telescopes in remote areas to avoid interference.
Murchison Widefield Array (MWA) (03:45)
Tingay heads to remote Western Australia, where 2,000 antennae spread over a square kilometer are tuned into the radio signal from the cosmic dawn. Opaque hydrogen gas produces signals that should correspond to a "Swiss cheese" image, once isolated.
Cosmic Dawn Signature (03:10)
At the Murchison Widefield Array, Tingay has gathered radio signals from the hydrogen fog surrounding the first stars. He plans to increase antennae numbers to map the early universe. Loeb compares the cosmic creation to Genesis in the Bible.
Credits: Cosmic Dawn - The Real Moment of Creation (00:45)
Credits: Cosmic Dawn - The Real Moment of Creation
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