The 9 Biggest Gaps in Our Understanding of Cosmic History
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Travel the universe with Dr. Ethan Siegel as he answers the biggest questions of all.
The answer to nature's greatest riddles are written upon the Universe itself.
Gaia's all-sky view of our Milky Way Galaxy and neighboring galaxies. The maps show the total brightness and color of stars (top), the total density of stars (middle), and the interstellar dust that fills the galaxy (bottom). Note how, on average, there are approximately ~10 million stars in each square degree, but that some regions, like the galactic plane or the galactic center, have stellar densities well above the overall average.
From the fundamental to the cosmic, science reveals our natural history.
Our Universe, from the hot Big Bang until the present day, underwent a huge amount of growth and evolution, and continues to do so. Our entire observable Universe was approximately the size of a modest boulder some 13.8 billion years ago, but it has expanded to be ~46 billion light-years in radius today. The complex structure that has arisen must have grown from seed imperfections of at least ~0.003% of the average density early on, and has gone through phases where atomic nuclei, neutral atoms, and stars first formed, eventually giving rise to our Solar System, planet, life, and humans.
Despite all we've learned, these nine major puzzles remain unsolved.
What triggered or preceded cosmic inflation?
What 'flavor' of inflation occurred?
How did baryogenesis occur?
What is the nature of dark matter?
How and when did the first stars appear?
How 'alone' are we in the Universe?
How did life on Earth begin?
What is dark energy's nature?
What's our ultimate cosmic fate?
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Travel the universe with Dr. Ethan Siegel as he answers the biggest questions of all.
