How the universe began—and how it is likely to end | Prof Carlos Frenk | TEDxDurham

Summary

The universe is expanding, a discovery made by Belgian priest Georges Lemaître and later rediscovered by Edwin Hubble. This led to the Big Bang theory, which suggests that the universe started from a highly dense and hot point 13.7 billion years ago. Today, we understand that the universe contains regular matter, dark matter, and dark energy. While dark matter is understood as a particle, dark energy remains a mystery, driving the accelerated expansion of the universe. Recent data challenges the current cosmological model, suggesting we may be missing a fundamental aspect of the universe's behavior, leading to new theories and ideas about its ultimate fate.

Takeaways

• 😀 The universe is expanding, and galaxies are moving away from us at speeds that increase with distance. This phenomenon is observed by all hypothetical observers, not just us.
• 😀 The discovery of the universe's expansion was first made by Belgian priest Georges Lemaître but was largely ignored until Edwin Hubble rediscovered it, which led to the renaming of Hubble’s law.
• 😀 The Big Bang, which occurred 13.7 billion years ago, resulted from the universe being extremely hot and dense, with all the stars and galaxies concentrated in a very small region.
• 😀 The early universe was foggy, but after 350,000 years, radiation was able to escape, marking the first light emitted by the universe, which has been traveling towards us ever since.
• 😀 The discovery of cosmic microwave background radiation by Penzias and Wilson provided direct evidence of the Big Bang.
• 😀 The expansion of the universe is not just happening but accelerating, which suggests the presence of something pushing the universe apart. This force is referred to as dark energy.
• 😀 The universe’s contents are bizarre: 5% consists of ordinary atoms, 25% is dark matter, and 70% is dark energy, which is responsible for the accelerated expansion.
• 😀 Dark matter is likely a type of particle that was produced shortly after the Big Bang, and it plays a critical role in our understanding of the universe.
• 😀 Einstein's cosmological constant (Λ) was initially introduced to explain the acceleration of the universe’s expansion, and it is a key part of the Standard Model of cosmology (Lambda-CDM).
• 😀 The Standard Model of cosmology, based on dark matter and dark energy, has been tested extensively but may be incomplete, as recent data suggests it may not fully explain the universe's behavior.
• 😀 A new paradigm may be required to understand the universe, as recent observations challenge the Lambda-CDM model and suggest we may be missing something fundamental about dark energy and the universe’s expansion.
• 😀 The future of the universe depends on the behavior of dark energy. If it increases, the universe could experience a 'Big Rip,' but if dark energy decreases, the universe might eventually recollapse in a 'Big Crunch,' potentially leading to new cycles of big bangs.

Q & A

What does the observation of galaxies moving away from us tell us about the universe?

It indicates that the universe is expanding, with galaxies moving away from us at speeds that increase proportionally to their distance. This observation suggests that the universe is not centered around us, but expanding uniformly in all directions.

Who was the first to propose the concept of an expanding universe, and why was it initially overlooked?

The concept of an expanding universe was first proposed by Belgian priest and astronomer Georges Lemaître. His papers were ignored for a time because they were written in French, and he faced challenges due to his background.

How was the Big Bang theory tested and confirmed?

The Big Bang theory was tested through the discovery of the cosmic microwave background radiation. This radiation, which had been emitted 350,000 years after the Big Bang, was detected by radio astronomers Arno Penzias and Bob Wilson in 1965.

What is dark energy, and how does it relate to the expansion of the universe?

Dark energy is a mysterious form of energy that is believed to be causing the accelerated expansion of the universe. It is not well understood, but it appears to be a dominant force driving galaxies apart at an increasing rate.

What percentage of the universe is made up of ordinary matter, dark matter, and dark energy?

Only 5% of the universe is composed of ordinary matter (the atoms we are familiar with). About 25% is dark matter, and the remaining 70% is made up of dark energy, which is responsible for the accelerated expansion of the universe.

How do scientists use computers to simulate the evolution of the universe?

Scientists use computers to model the physics of the universe, solving equations that describe the evolution of dark matter, ordinary matter, and the expansion of the universe. These simulations help scientists visualize cosmic structures like galaxies and understand their formation.

What is the Standard Model of Cosmology, and what does it include?

The Standard Model of Cosmology, also known as Lambda-CDM, includes the cosmological constant (lambda, associated with dark energy) and cold dark matter (CDM). It serves as the foundation for our understanding of the universe's structure and expansion.

What does the recent discovery about dark energy imply for the future of the universe?

Recent data, specifically from the Dark Energy Spectroscopic Instrument, suggest that the current understanding of dark energy may be incorrect. The discovery indicates that we are missing something fundamental in our model of the universe, which may change our predictions about the universe's fate.

What are the three potential outcomes for the future of the universe based on dark energy behavior?

The three potential outcomes are: 1) The Big Rip, where dark energy increases and tears the universe apart. 2) The Heat Death, where the universe continues expanding forever, eventually leading to a cold, lifeless state. 3) A Big Crunch, where the universe collapses in on itself after dark energy diminishes, potentially starting the cycle again.

Why does the speaker find the possibility of a Big Crunch more appealing than other theories?

The speaker finds the Big Crunch more appealing because it suggests a cyclical nature for the universe, where it could collapse and restart in new Big Bangs, offering a more optimistic and philosophical view compared to the cold, unchanging endings predicted by other models like the Big Rip or Heat Death.