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Infinite Worlds: A Journey through Parallel Universes

World Science Festival・85 minutes read

Our understanding of the universe has evolved significantly, from being the center of it to just one of many universes, with concepts such as gravity, General Theory of Relativity, the expanding universe, the Big Bang, cosmic microwave background radiation, and inflation shaping cosmology theories. The multiverse theory proposes the existence of multiple universes, each with unique properties, challenging traditional ideas about the universe's origins, with string theory and the simulation argument offering further perspectives on the universe's complexity and potential infinite vastness.

Insights

Gravity, as described by Newton, is fundamental for space travel and celestial body movements, reliant on mass and distance equations.
Edwin Hubble's observations confirmed an expanding universe, solidifying the Big Bang theory's validity and transforming cosmology into a quantitative science.
The multiverse theory posits an eternal future with continuous universe creation, presenting a vast array of potential universes with different physical constants.

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Recent questions

What is the Big Bang theory?
The Big Bang theory posits that the universe began as a small, hot entity that expanded, leading to the formation of galaxies and stars.
How does inflation explain the universe's characteristics?
Inflation, a rapid expansion phase, accounts for the universe's flatness, uniformity, and clumpiness by smoothing out quantum fluctuations.
What is the multiverse theory?
The multiverse theory suggests the existence of multiple universes resulting from inflationary bursts, visualized as an expanding gaseous realm with bubbles of universes.
How does string theory relate to the universe's properties?
String theory explores multiple dimensions and offers explanations for the universe's characteristics, aligning with the anthropic principle to ensure livable conditions.
What is the simulation argument?
The simulation argument proposes the idea of the universe being a computer simulation, presenting possibilities of civilizations creating simulations, living in simulations, or facing extinction.

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Summary

00:00

"Evolution of Universe: From Demotions to Discoveries"

Over the centuries, our understanding of the universe has expanded significantly, leading to a series of demotions for humanity from being at the center of the universe to just one of many universes.
Gravity, as explained by Newton in the 1600s, is based on an equation involving the mass and distance of objects, crucial for space travel and understanding celestial bodies' movements.
Einstein's General Theory of Relativity, developed in the early 20th century, delved into the mechanism behind gravity, proposing that space itself is curved by massive objects, affecting the motion of other objects.
The concept of an expanding universe was initially met with skepticism, with Einstein himself dismissing it until Edwin Hubble's observations in 1929 confirmed that distant galaxies were moving away, indicating an expanding universe.
The expanding universe theory led to the concept of the Big Bang, where the universe started as a small, hot entity that expanded, cooling down to form galaxies and stars.
George Gamow, a physicist, proposed the existence of residual heat from the Big Bang, suggesting that this remnant radiation should be detectable in space, a theory later confirmed by Penzias and Wilson's discovery of cosmic microwave background radiation.
Gamow's initial proposal, made in jest with a colleague, was not taken seriously, but later researchers like Robert Dicke and Jim Peebles independently arrived at similar conclusions, leading to the confirmation of cosmic microwave background radiation.
Penzias and Wilson's discovery of cosmic microwave background radiation solidified the Big Bang theory, marking a significant moment in cosmology and transforming it into a quantitative science.
The confirmation of cosmic microwave background radiation through observations, including a second Nobel Prize awarded for these findings, provided a means to test and validate theories about the universe's origin and evolution.

16:16

"Big Bang Theory and Multiverse Debate"

Theoretical curve shows heat and photon distribution post-Big Bang
Observations match theoretical curve, supporting Big Bang theory
Big Bang theory lacks explanation for initial outward expansion
Alan Guth, Andre Linde, Paul Steinhardt, and Andreas Albrecht propose repulsive gravity theory
Inflationary cosmology suggests energy field causing outward push
Quantum fluctuations in early universe lead to hot and cold spots
Data from 13.5 billion years ago matches theoretical curve
Multiverse theory proposes multiple universes from inflationary bursts
Multiverse concept visualized as expanding gaseous realm with bubbles of universes
Debate exists among scientists regarding the multiverse theory

37:15

"Before Big Bang: Multiverse Theory Explored"

In cosmology, the concept of what occurred before the Big Bang is a challenging question with no universal answer.
In the traditional Big Bang theory, time and space originated with the event, making the notion of "before" irrelevant.
The multiverse theory alters perspectives on the Big Bang's prelude.
The universe, post-Big Bang, began as a dense, hot soup that eventually evolved into galaxies and clouds.
The concept of inflation, a rapid expansion phase, explains the universe's flatness, uniformity, and clumpiness.
Inflation, occurring in a fraction of a second, led to a universe expanding by a factor of 10^25.
The universe's expansion was due to a repulsive gravitational effect from a peculiar field.
Inflation smoothed out quantum fluctuations, leading to the formation of galaxies.
The universe's shape, starting potentially round, became flat due to inflation's stretching effect.
The graceful exit problem addresses how multiple universes can arise from the initial inflationary universe through bubble collisions and expansions.

52:48

"Multiverse Expansion: Colors, Inflation, and Boundaries"

Computer simulations are used to demonstrate the expansion of the universe, with x and y axes representing energy density levels.
Quantum fluctuations cause inhomogeneities in the universe, leading to the creation of new parts that expand faster.
The Planck satellite is launched to study these fluctuations and is expected to provide data in three years.
Different colored regions in the universe signify varying properties, akin to different states of water.
The universe is depicted as a multicolored entity, with each color representing a different universe within bubbles.
The universe's expansion leads to vast distances between different universes, making crossing boundaries nearly impossible.
Objects in different universes can move away from each other faster than the speed of light due to space expansion.
The concept of a multiverse suggests an eternal future with the continuous creation of new universes.
Inflationary theory explains the universe as a fractal, with the multiverse displaying all possible colors and properties.
The number of stable compactifications in a six-dimensional space is estimated to be 10^500, indicating a vast array of potential universes.

01:09:46

"Multiverse Theory: Exploring Infinite Possibilities"

A theory suggesting anything is possible lacks explanatory power, encompassing every conceivable scenario in a multiverse.
In a vast universe, all possible observers exist, leading to a challenge in testing theories due to consistent predictions for all observations.
The concept of fine-tuning in our universe raises questions about the likelihood of life and intelligent beings existing elsewhere.
The idea of a multiverse posits that various universes with different physical constants exist, explaining fine-tuning as a result of observer presence.
String theory explores multiple dimensions, initially aiming to find one shape for extra dimensions but discovering 10 to the 500 possibilities.
Cosmologists discovered dark energy causing the universe's exponential expansion, initially posing a challenge to string theory until a solution was found.
The vacuum energy's minuscule value, 10 to the -120 of the expected value, was explained through 10 to the 500 different states in string theory.
String theory's ability to describe the universe with tiny vacuum energy values aligns with the anthropic principle, ensuring livable conditions.
String theory, combined with inflationary theory, offers the best explanation for experimental data, with no superior alternatives proposed.
Bryce DeWitt's review of the multiverse concept highlights the challenge of accepting the idea of countless copies of oneself, questioning common sense.

01:25:19

"Exploring Multiverse Theories: Beauty and Significance"

John Wheeler and Mr. Uno discuss the complexity of believing in multiple universes created by nobody compared to a single universe with one creator.
Physicist John S. Bell criticizes the idea of countless parallel universes as "silly."
Different flavors of parallel universes are discussed, with a focus on the inflationary cosmology version and the quantum mechanical interpretation.
The discovery of the universe's accelerating expansion in 1998 led to the consideration of multiple universes to explain the small value of dark energy.
The concept of parallel universes colliding and leaving ripples on radiation is explored as a potential way to test these ideas.
The simulation argument proposes the idea of a universe being a computer simulation, with detailed explanations on how this could be possible.
Three possibilities are presented by the simulation argument: civilizations going extinct, losing interest in creating simulations, or living in a computer simulation.
The argument suggests that there could be many more simulated realities than original ones due to the ease of creating simulations.
The implications of the simulation hypothesis are discussed, emphasizing that even if we are in a simulation, our methods of predicting and acting remain the same.
The discussion concludes with reflections on the beauty and significance of a multiverse concept, with a focus on how understanding the universe's complexity can be energizing and awe-inspiring.

01:40:00

"Vastness of Shanghai and Universal Complexity"

Leaving Manhattan for Shanghai can make New York seem smaller upon return due to Shanghai's vastness. The concept of the universe being infinite already provides immense vastness, even without considering multiple universes.
In the Mahabharata, Krishna reveals his universal form to a warrior, showcasing a deity that encompasses all aspects of creation and destruction. Nature's complexity continues to surprise and excite as understanding deepens, offering both beauty and challenges in comprehension.

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