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Universe Expansion
The planet, the Solar System, and the galaxy aren't expanding. But the whole Universe is. So where does the dividing line begin?
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.
Red dwarfs are the Universe's most common star type. Their flaring now makes potentially Earth-like worlds uninhabitable, but just you wait.
Observations with the Hubble space telescope helped cement dark energy and reveal the Hubble tension. How are these two things so different?
As the Universe ages, it continues to gravitate, form stars, and expand. And yet, all this will someday end. Do we finally understand how?
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 look to larger cosmic scales, we get a broader view of the expansive cosmic forest, eventually revealing the grandest views of all.
The Universe isn't just expanding; the expansion is accelerating. If different methods yield incompatible results, is dark energy evolving?
The Universe was born incredibly hot, and has expanded and cooled ever since. Could life have begun back when space was "room temperature?"
Just 13.8 billion years after the hot Big Bang, we can see 46.1 billion light-years away in all directions. Doesn't that violate...something?
On the largest scales, galaxies don't simply clump together, but form superclusters. Too bad they don't remain bound together.
The Big Bang was hot, dense, uniform, and filled with matter and energy. Before that? There was nothing. Here's how that's possible.
When the Hubble Space Telescope first launched in 1990, there was so much we didn't know. Here's how far we've come.
Once you cross a black hole's event horizon, there's no going back. But inside, could creating a singularity give birth to a new Universe?