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Dark Energy
The standard picture of our Universe is that it's dominated by dark matter and dark energy. But this alternative is also worth considering.
On the largest of cosmic scales, the Universe is expanding. But it isn't all-or-nothing everywhere, as "collapse" is also part of the story.
The Universe's history, from cosmic inflation to the Big Bang to the present, is known. But whether it's infinite or not is still a mystery.
There are two different ways to measure the expansion rate of the Universe, and they don't agree. And no, new measurements don't help.
Is gravity weaker over distances of billions of light-years?
The Universe is precisely dated at 13.8 billion years old, but astronomers claim the Methuselah star is 14.5 billion years old. What gives?
Predicted way back in the 1960s, the discovery of the Higgs boson in 2012 completed the Standard Model. Here's why it remains fascinating.
The expanding Universe, in many ways, is the ultimate out-of-equilibrium system. After enough time passes, will we eventually get there?
For nearly 25 years, we thought we knew how the Universe would end. Now, new measurements point to a profoundly different conclusion.
The mutual distance between well-separated galaxies increases with time as the Universe expands. What else expands, and what doesn't?
We normally think of dark matter as the "glue" that holds galaxies and larger structures together. But it's so much more than that.
The evidence that the Universe is expanding is overwhelming. But how? By stretching the existing space, or by creating new space itself?
Holograms preserve all of an object's 3D information, but on a 2D surface. Could the holographic Universe idea lead us to higher dimensions?
From the earliest stages of the hot Big Bang (and even before) to our dark energy-dominated present, how and when did the Universe grow up?
Dark energy is one of the biggest mysteries in all the Universe. Is there any way to avoid "having to live with it?"
The Universe is expanding, and the Hubble constant tells us how fast. But how can it be a constant if the expansion is accelerating?
Here's what recent DESI measurements suggest — and why it's too early to update conventional predictions about the Universe's distant future.
In all the Universe, only a few particles are eternally stable. The photon, the quantum of light, has an infinite lifetime. Or does it?
Yes, the Universe is expanding, but if you've ever wondered, "How fast is it expanding," the answer isn't in terms of a speed at all.
Is the Universe finite or infinite? Does it go on forever or loop back on itself? Here's what would happen if you traveled forever.
The Universe is 13.8 billion years old, going back to the hot Big Bang. But was that truly the beginning, and is that truly its age?
Because of dark energy, distant objects speed away from us faster and faster as time goes on. How long before every galaxy is out of reach?
When cosmic inflation came to an end, the hot Big Bang ensued as a result. If our cosmic vacuum state decays, could it all happen again?
Without wormholes, warp drive, or some type of new matter, energy, or physics, everyone is limited by the speed of light. Or are they?
Early on, only matter and radiation were important for the expanding Universe. After a few billion years, dark energy changed everything.
On the largest cosmic scales, galaxies line up along filaments, with great clusters forming at their intersection. Here's how it took shape.
Astronomers claim to have found structures so large, they shouldn't exist. With such biased, incomplete observations, perhaps they don't.
For every proton, there were over a billion others that annihilated away with an antimatter counterpart. So where did all that energy go?
A new measurement offers insights on the density of the mysterious force driving the Universe's expansion.
Today, the star-formation rate across the Universe is a mere trickle: just 3% of what it was at its peak. Here's what it was like back then.