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Big Bang Theory
Ask Ethan: Why couldn’t the Universe have expanded forever?
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 still don’t know how “hot” the hot Big Bang was
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.
Cosmic inflation’s biggest criticisms can’t undermine its success
Inflation's two main criticisms, that it can predict anything and that the "measure problem" remains unsolved, can't erase its successes.
Ask Ethan: How many generations of stars came before the Sun?
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?
Ask Ethan: How and when will the Universe die?
As the Universe ages, it continues to gravitate, form stars, and expand. And yet, all this will someday end. Do we finally understand how?
What do distant observers see when they look at Earth?
From here on Earth, looking farther away in space means looking farther back in time. So what are distant Earth-watchers seeing right now?
Ask Ethan: Where are we located relative to the Big Bang?
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?
Even before the Big Bang, space wasn’t truly empty
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 strongest evidence for a Universe before the Big Bang
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.
The Big Bang doesn’t mean what it used to
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.
Science’s answer to the ultimate question: Where do we come from?
Questions about our origins, biologically, chemically, and cosmically, are the most profound ones we can ask. Here are today's best answers.
Ask Ethan: Did life begin when the Universe was room temperature?
The Universe was born incredibly hot, and has expanded and cooled ever since. Could life have begun back when space was "room temperature?"
Ask Ethan: Did our Universe really arise from nothing?
The Big Bang was hot, dense, uniform, and filled with matter and energy. Before that? There was nothing. Here's how that's possible.