expanding universe
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From the First Nuclei to First Light
When we talk about the first 30 minutes of time, we describe the universe expanding and cooling. As the universe cooled, the nuclear reactions that produced the first atomic nuclei slowed and stopped. But it was only relatively cool. The…
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The First Nucleosynthesis
One minute after the Big Bang, all the protons, neutrons, and electrons that would ever exist had been produced. There were no atomic nuclei, though. No atoms. No materials as you and I know it — like wood, metal, or…
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The Universe’s First Moments
Imagine a time before galaxies existed, before the first stars had been born, before the most basic building blocks of matter — atoms — had formed. This was mere moments after the Big Bang. No one understands how matter and…
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What was the Big Bang?
Have you heard of the Big Bang? I still remember the first time I heard about it. I was little; I can’t remember if I’d fallen in love with astronomy yet. But I do remember sitting in my living room,…
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What is Cosmology?
Cosmology is the study of the universe itself: how it came to be, how it has behaved since, and why the laws of physics operate the way they do. It’s one of the strangest branches of science — second only,…
