The First Fraction of a Second | Crash Course Pods: The Universe #1

Introduction (0s)

• Katie Mack's book, "The End of Everything", discusses the beginning, expansion, and end of the universe.
• The author and Dr. Mack decided to create a podcast together to discuss the history of the universe.
• The first episode focuses on the Big Bang and how it relates to humans.
• The question of why there is a universe is considered boring and has no empirical approach to establishing purpose.
• It is unknown why there is stuff in the universe.

There Shouldn’t Be Stuff (4m0s)

• The concept of matter-antimatter asymmetry suggests that there should be an equal amount of matter and antimatter in the universe.
• If matter and antimatter collide, they annihilate each other, creating gamma rays.
• The universe is mostly made of matter, with very little antimatter.
• There must have been something that changed the balance between matter and antimatter in the early universe.
• Scientists have a good understanding of what happened in the first second of the universe.
• They can go back even earlier, to a fraction of a nanosecond after the Big Bang.
• There is strong theoretical and experimental evidence for what happened in this time.
• Before this point, things get fuzzy and uncertain.

The Big Bang Theory (8m53s)

• The Big Bang Theory suggests that the universe began as a hot and dense state approximately 13.8 billion years ago.
• The expansion of the universe is observed through the redshift of light from distant galaxies, indicating that the universe is expanding and creating more space between objects.
• The cosmic microwave background radiation, the remnant light from the hot dense early universe, confirms the Big Bang Theory.
• The observable universe is the part of the universe that we can see from our location in space, and it is expanding faster than it did yesterday.
• The universe might be much larger than our observable universe and could be infinitely large, with no evidence of an edge.

We’re Not Sure About The Singularity (21m28s)

• The concept of the Singularity suggests that the Universe originated from an infinitely small point and has been expanding ever since. However, observations of the early Universe contradict this idea, revealing a high degree of uniformity.
• Cosmic inflation is a proposed period of rapid expansion in the very early Universe that could explain the observed uniformity.
• The expansion of the universe is not uniform, and the farther away objects are, the faster they move apart.
• Inflation theory suggests that the early universe was not perfectly uniform in temperature but had fluctuations.
• Inflation focuses on a tiny part of the early universe where the temperature is the same and uses that as the starting point for the entire observable universe.

Cosmic Inflation (32m0s)

• The beginning of the universe was not an infinitely small point, but rather different parts that were super close together and in balance.
• During cosmic inflation, these parts moved rapidly away from each other, expanding the universe.
• Cosmic inflation acts like a cosmic microscope, helping us see quantum fluctuations in the early universe and explaining the uniformity of the background light.
• We don't know what came before cosmic inflation because it invented the idea of "before."
• Cosmic inflation pushes the singularity problem aside, making it irrelevant whether it happened or not.
• We can't have any information from before inflation, making it observationally impossible to know if anything happened before.
• The first thing we know about the universe is that it was very hot and dense, then expanded through cosmic inflation.
• Cosmic inflation lasted for about 10^-34 seconds, an incredibly tiny fraction of a second.
• During this time, the universe expanded by a factor of 100 trillion trillion.

The First Second (36m26s)

• Astronomers believe that inflation ended with a big dump of energy into the universe, creating a hot and dense state.
• Scientists can calculate the temperature and density of the universe at that time by smashing particles together in particle colliders, simulating the conditions of the early universe.
• During the Quark era, which lasted for about a microsecond, the universe was a Quark-gluon plasma, where quarks and gluons were separated.
• The electromagnetic force and the weak nuclear force separated during this time.
• Scientists can create a Quark-gluon plasma in a laboratory by smashing particles together, allowing them to sample the conditions of the early universe and observe how the laws of physics change at high energies.
• The first fraction of a second of the universe's existence is well-understood due to the ability to calculate the temperature and density of the universe at that time.
• Particle colliders can simulate the conditions of the early universe, allowing scientists to study the Quark era and the separation of the electromagnetic force from the weak nuclear force.
• The Quark era lasted for about a microsecond in the early universe.
• During this time, the universe was a Quark-gluon plasma, where quarks and gluons were separated.
• Scientists can create a Quark-gluon plasma in a laboratory by smashing particles together, allowing them to sample the conditions of the early universe and observe how the laws of physics change at high energies.

The First Two Minutes (38m43s)

• The universe was initially too hot for protons, neutrons, and electrons to form, but as it cooled, these particles emerged.
• Around 2 minutes after the Big Bang, atoms started forming through Big Bang nucleosynthesis, creating hydrogen, helium, and trace amounts of other elements.
• Most of the hydrogen atoms in our bodies originated directly from the early universe and have not been through a star.
• Protons, which make up hydrogen nuclei, are extremely stable and have a decay time estimated to be longer than 10^40 seconds.
• The atoms that make up living organisms are constantly recycled and may eventually become part of other living things.
• The cosmic microwave background radiation is the leftover thermal radiation from the early universe and is visible to us today.

Outro (46m48s)

• John Green thanks the listeners for listening to the first episode of the podcast, "The Universe."
• He expresses his personal fascination with unpacking the strangeness of life and the universe as a way to find meaning.
• Green highlights the significance of the fact that there is more matter than antimatter in the universe, even though the reason for this is unknown.
• He emphasizes that finding meaning in the universe is a personal endeavor and invites listeners to join him in exploring the mysteries of the cosmos.
• The show is hosted by John Green and Dr. Katie Mack.
• This episode was produced by Hannah West, edited by L Openhouse, and mixed by Joseph Tuna Medish.
• The editorial directors are Dr. Darcy Shapiro and Megan Moery.
• The executive producers are Heather D. Diego and Seth Radley.
• The show is a production of Complexly.
• Listeners can support the show by joining the community on Patreon at patreon.com/crashcourse.