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Big Bang Theory
For 13.8 billion years, the Universe has been expanding. But that couldn't have been the case for an eternity, and science has proven it.
We've long known we can't go back to infinite temperatures and densities. But the hottest part of the hot Big Bang remains a cosmic mystery.
Inflation's two main criticisms, that it can predict anything and that the "measure problem" remains unsolved, can't erase its successes.
Our Sun only arose after 9.2 billion years of cosmic history: with many stars living and dying first. How many prior generations were there?
As the Universe ages, it continues to gravitate, form stars, and expand. And yet, all this will someday end. Do we finally understand how?
From here on Earth, looking farther away in space means looking farther back in time. So what are distant Earth-watchers seeing right now?
If you think of the Big Bang as an explosion, we can trace it back to a single point-of-origin. But what if it happened everywhere at once?
All of the matter that we measure today originated in the hot Big Bang. But even before that, and far into the future, it'll never be empty.
The hot Big Bang is often touted as the beginning of the Universe. But there's one piece of evidence we can't ignore that shows otherwise.
As we gain new knowledge, our scientific picture of how the Universe works must evolve. This is a feature of the Big Bang, not a bug.
Questions about our origins, biologically, chemically, and cosmically, are the most profound ones we can ask. Here are today's best answers.
The Universe was born incredibly hot, and has expanded and cooled ever since. Could life have begun back when space was "room temperature?"
The Big Bang was hot, dense, uniform, and filled with matter and energy. Before that? There was nothing. Here's how that's possible.