SECTION
Where did it all begin?
The Big Bang, the first second, the size of the cosmos and where our atoms came from: what is established, what is debated, and what is still open.
FROM THE QUESTION LIBRARY
OriginsAnswer
Several serious ideas in physics allow other universes, so here is what each one says, how scientists have tried to test them, and how a scientific braneworld differs from the multiverse in the movies.
OriginsAnswer
Scientists have measured the hot early universe in detail, but whether time itself had a first moment is still an open question.
OriginsAnswer
About 13.8 billion years, read from the oldest light in the sky and checked against the oldest stars, with one real puzzle still open about how fast space is stretching today.
OriginsAnswer
Cosmic expansion means distances between faraway galaxies grow; it does not require a wall, an edge, or a room beyond space.
OriginsAnswer
Many physicists say life depends on a few numbers of nature falling in narrow ranges, so here is what that means, why 137 is famous, and how design, many universes and luck each try to explain it.
OriginsAnswer
The part we can see has a limit, space looks flat, and flat can still mean finite, so here is what the evidence says and why the final answer may stay out of reach.
OriginsAnswer
An earlier history needs a calculable path to a measurement that separates it from competing explanations.
OriginsAnswer
Physics can trace the universe back a long way, but every answer starts with something already there, so here is what science, faith and philosophy each offer.
OriginsEssay · personal view
To another intelligence, we might not be “humans” at all, but one highly social species of living organism—technologically remarkable, biologically related to the rest of life, and still learning what consciousness means.
OriginsEssay · personal view
The Big Bang explains an early hot, dense universe. It may not be the first page of reality. Here is my best current hypothesis—and the evidence that would have to judge it.
OriginsExplainer
From the first atomic nuclei back to a possible burst of inflation, here is what scientists have tested about the first second, and where knowledge runs out.
OriginsExplainer
The part we can see is about 93 billion light-years wide, but whether the whole universe ends, loops back or goes on forever is still unknown.
OriginsExplainer
Distant light lets us look far into the past. But the earliest light we can receive arrived after the universe had already been changing for a long time.
OriginsExplainer
An unseen direction in space is a serious possibility in some models. What would it change in a detector, and what would count as evidence?
OriginsExplainer
LIGO measured tiny changes in distance and opened another way to study the universe.
OriginsExplainer
A star’s light comes from fusion. Its long history also helps explain the matter that makes planets and people.
OriginsExplainer
The hot early universe has strong observational support; the ultimate beginning remains an open question.
The Architect AI companion · All Access
