Extrapolating Forward (03:14)
Scientists understand that the universe came into being 13.8 billion years ago. The universe operates on a massive time scale. Is it possible to predict the end of the universe?
History of Stars (02:20)
Some of the light visible in the night sky took billions of years to reach the Earth. In the late 1940s, mathematician and physicist Fred Hoyle wanted to know where the elements originated.
Life Cycle of Stars (02:49)
Nuclear fusion is a process where simple, light elements fuse together to create more complex stars. Fred Hoyle concocted a theory that would explain the way stars change throughout their lives
Tracking Star Evolution (03:55)
Astronomers grouped stars based on size, color, and brightness on the Hertzsprung-Russell Diagram. In Hoyle's theory, once a star runs out of helium, it expands and becomes a red giant, and finally produces carbon.
High Energy Carbon (03:51)
Hoyle demanded CalTech use the particle accelerator to look for his high energy carbon. They eventually yielded and found what he predicted. See a recreation of the experiment.
"Stars Govern Our Conditions" (02:24)
Hoyle's discovery provided insight into the life cycle of stars, allowing scientists to predict the future of the universe. Hydrogen and helium formed stars, and were then consumed as the stars aged.
Capturing the Spectrum (04:06)
In the 1900s, astronomers were interested in nebulae. Vesto Slipher was particularly interested in the motion of nebulae and chose to study Andromeda.
Major Breakthrough on Nebulae (03:53)
Slipher was the first to measure the speed of nebulae and received a standing ovation when he presented the information at an astronomy meeting. Andromeda is now known to be a galaxy.
Calculating Critical Density (03:53)
The changing expansion of the universe was thought to prove critical density, until graduate student Beatrice Tinsley noted a flaw in the plan. Al Khalili demonstrates how to measure distance with light.
Measuring the Universe (04:13)
To measure the distance of galaxies, astronomers assumed the brightness of galaxies did not change. Tinsley proved that galaxies and their brightness would be affected by the life cycle of stars.
Clusters and Super-clusters (03:45)
Margaret Geller mapped the scale of the universe. This provided evidence of the universe's structure for the first time.
Fritz Zwicky (03:00)
Astronomer Zwicky measured the strength of gravity holding matter clusters together. He coined the term "dark matter."
Red Shifted Quasars (03:49)
In the 1973, experts observed two quasars close together, inciting the interest of the scientific community. They were so similar that the scientists thought they measured the same quasar twice.
Single or Double Quasar? (02:56)
Mass dictates space warp which dictates the amount of light bent. Bent light made a single quasar appear as two. The double images was important for studying dark matter.
Type 1A Supernovae (04:33)
To measure the expansion of the universe, researchers looked to supernovae. The red shift of light shows the amount of space that expanded, giving a measure of the size of the universe.
Gravity's Brakes (03:23)
The changing size of red shifts indicates the universe's rate of expansion is accelerating. Dark energy describes 70% of the universe and is responsible for the expansion of the universe.
Fate of the Universe (02:16)
Because of how little is known about dark energy, the future of the universe is unpredictable. It could pose a problem of scientific theories that are currently well trusted.
Credits: The End of the Universe (00:40)
Credits: The End of the Universe
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