Quintessential Human Questions (03:50)
Until 100 years ago, scientists considered the universe to be eternal and unchanging. For most of human history, only religion could attempt to explain life's biggest questions.
Mystery in the Sky (02:49)
In the early 20th century, the Milky Way galaxy was thought to be the extent of the universe, until Andromeda sparked questions. Scientists wondered whether the nebula was a sort of star nursery or an entirely seperate galaxy.
Real Astronomical Gold (04:05)
Famous astronomer Edwin Hubble used a telescope in Southern California to discover a star that changed in brightness in the Andromeda nebula. Today, the largest telescope is the Gran Telescopio Canarias, or the GTC.
Very Far Away Star (02:57)
Hubble discovered a Cepheid variable star, the type of star that has a changing brightness that allows scientists to figure out its distance. Studying the variations in the luminosity of the star allowed Hubble to discern that the star was the most remote object ever recorded, making Andromeda a galaxy.
Cause of Gravity (03:59)
A hundred years ago, Albert Einstein proposed his theory of relativity and created the theoretical foundation required to study the universe. Through the logic of his theory, Einstein figured that the gravity of the universe would gradually pull all the objects in the universe together: the collapse of the universe.
Origin of the Universe (02:45)
Georges Lemaître used Einstein's theory to create his own cosmological model, a model so radical that the scientific community was divided. He proposed that the universe is expanding and this led to the Big Bang Theory.
Dismissal of Dynamic Universe (03:02)
Lemaître approached Einstein to attempt to gain Einstein's endorsement of this cosmological model. Meanwhile, Hubble was measuring the rate at which other galaxies appeared to be receding from Earth.
Red Shift of Galaxies (04:14)
Al Khalili practices observing the shift of galaxies in a more advanced fashion than Hubble and partner Milton Humason did. Advents in technology make for quicker, more accurate observations.
Cosmological Revolution (03:13)
Hubble's observation of other galaxies moving away from Earth faster if they were far away from Earth suggested that the universe was expanding. This was the first observation that supported Lemaître's idea and Einstein publicly endorsed it.
What is the Universe Made Of? (03:25)
Astronomers like Cecilia Payne began looking into the composition of the universe. To study the composition of the sun, astronomers used a unique method that is still the basis of modern-day telescope Vacuum Tower Solar Telescope, as Khalili demonstrates.
Hydrogen and Helium (03:45)
Initially, astronomers observed elements in the sun to be remarkably earth-like, until Payne's calculations revealed that relative abundance was distorting the observations. Her work was dismissed until it was re-created by another scientist through a different approach.
Supporters of the Big Bang Theory (04:42)
Russian nuclear physicist George Gamow and cosmologist Ralph Alpher worked on an idea of the universe, rewinding it mathematically and coming to the conclusion that it was once incredibly hot and dense. It was built around the concept of nuclear fusion.
Nobel Prize Winners (03:14)
Scientists Arno Penzias and Robert Wilson were using an instrument called a horn antenna to make observations. In order to use it, they first had to eliminate background radiation that was obscuring their calculations.
Celestial Ear Trumpet (02:01)
Penzias and Wilson accidentally stumbled across the radiation that Alpher had predicted but had not been able to successfully measure. It proved the Big Bang Theory.
Secrets of the Primordial Universe (03:11)
The largest particle accelerator in the world is housed at CERN, where scientists continue to work to answer questions regarding the beginning of the universe. Al Khalili visits CERN and investigates the unique reactions created by the collisions.
Confinement of the Quarks (04:43)
Al Khalili details how the Large Hadron Collider squeezes energy down to a minute density. An image of tens of thousands of particles post-explosion shows evidence of the plasma created by the collision.
Super-Fast Expansion (02:42)
Studying the collisions at CERN allows scientists to hypothesize about the earliest stages of the universe. Abstract theory and speculation dominate ideas of the earliest moments of the universe.
Credits: The Beginning of the Universe (00:23)
Credits: The Beginning of the Universe
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