Universe · 13.8 billion years

The Evolution of the Universe

Move through 13.8 billion years of cosmic history. Drag the timeline, choose a milestone, or press Play to watch matter cool, form stars and galaxies, and leave the microwave background we still observe today.

Elapsed time 13.80 Gyr
Redshift z 0
Temperature 2.73 K
Scale factor a 1.00
13.80 Gyr

Dark-energy era

Dark energy keeps stretching space, and the cosmic web keeps drifting apart.

Non-linear time · real-time GPU simulation · illustrative physics

How to read the map

The stage settles into a logarithmic slice of the observable universe: the Sun at the centre, the Milky Way and its neighbours in the middle, and the Big Bang's afterglow at the rim. Every marker on the map is now a live callout with its key facts and links. Follow any of them to go deeper.

The Big Bang in five steps

The Big Bang is not an explosion into empty space. It is the expansion of space itself from a hot, dense state about 13.8 billion years ago. The whole story, briefly:

  1. The beginning

    All of space, time, matter and energy begin in an unimaginably hot, dense state. Our current physics cannot yet describe the very first instant: the Planck era.

  2. Inflation

    In a fraction of a second, space expands by an enormous factor, stretching itself flat and smooth, and stamping in the tiny ripples that later grow into galaxies.

  3. First particles and nuclei

    Within minutes, quarks bind into protons and neutrons, which fuse into hydrogen, helium and a trace of lithium, the lightest elements.

  4. First light

    After about 380,000 years, electrons latch onto nuclei, the fog clears, and light streams free. Stretched by expansion, that light is today's cosmic microwave background.

  5. Stars, galaxies and us

    Over hundreds of millions of years, gravity gathers matter into the first stars and galaxies. The Solar System forms about 9.2 billion years later, and life follows on Earth.

Read the full chronology: Chronology of the universe · Big Bang.

The universe's expected lifetime

We are 13.8 billion years into a story whose ending lies far in the future. These are the eras cosmology expects ahead (approximate, illustrative, and still being refined):

  1. Now → ~10¹⁴ yearsStelliferous era: stars keep forming until the raw gas runs out, then the last stars fade.
  2. ~10¹⁴-10⁴⁰ yearsDegenerate era: the cosmos is left to white dwarfs, neutron stars and black holes; matter may slowly dissolve if protons decay.
  3. ~10⁴⁰-10¹⁰⁰ yearsBlack-hole era: black holes dominate, then evaporate away through Hawking radiation.
  4. Beyond ~10¹⁰⁰ yearsDark era, or heat death: the universe approaches a near-uniform, cold, dark state of maximum entropy.

If dark energy strengthens, a Big Rip could tear everything apart first; if expansion ever reversed, a Big Crunch would follow. Neither is favoured by current data. Learn more about the ultimate fate and the heat death of the universe.

Photos

Real light, captured by telescopes. Each image links to its source.

Webb's First Deep Field: thousands of galaxies around the galaxy cluster SMACS 0723
Webb's First Deep Field: thousands of galaxies, some seen as they were billions of years ago.
Planck all-sky map of the cosmic microwave background with subtle temperature variations
The cosmic microwave background: the oldest light in the universe, mapped by Planck.
Hubble eXtreme Deep Field: a dense field of faint, distant galaxies
The Hubble eXtreme Deep Field: over a decade of staring at one tiny patch of sky.
Ultraviolet view of the Andromeda Galaxy showing its bright disc and star-forming rings
Andromeda in ultraviolet light: our nearest large galactic neighbour.

Simulations and interactives

Watch the universe evolve in real time, from full cosmological simulations to NASA's own orbiters and telescopes.

IllustrisTNGSimulationA full cosmological simulation of galaxies, gas, stars, black holes and magnetic fields. IllustrisSimulationThe predecessor of TNG: a simulated cube of the universe where cosmic structure forms. NASA's EyesInteractiveReal-time visual apps for the Solar System, exoplanets, asteroids and Earth. WMAP cosmologyReferenceNASA's illustrated guide to the Big Bang, expansion, the CMB and dark energy.

Frontiers, theories and ideas on the edge

Cosmology is a live subject. These are the open questions, competing models and speculative ideas, each with its own page.

The Hubble tensionOpen questionTwo ways of measuring cosmic expansion disagree. Dark energyOpen questionExpansion is accelerating, and no one knows what drives it. Early galaxiesOpen questionJWST finds galaxies that look too mature for their age. Gravitational-wave humOpen questionPulsar timing arrays hear a low rumble across the sky. String theory / M-theoryAlternative theoryParticles as vibrating strings, with extra dimensions. Loop quantum gravityAlternative theorySpace-time built from tiny loops, with a bounce instead of a singularity. Cyclic universeAlternative theoryThe Big Bang as one turn of an endless cycle. Inflation's variantsAlternative theoryThe leading model for the universe's smoothness, with many versions. MultiverseIdea on the edgeOur universe as one member of a vast ensemble. Extra dimensionsIdea on the edgeHidden directions curled up inside every point. White holesIdea on the edgeThe time-reversed twin of a black hole. WormholesIdea on the edgeTunnels through space-time that could link distant places. Vacuum decayIdea on the edgeA rare quantum event that could rewrite physics as it spreads.

Further reading: Hubble's law · dark energy · James Webb Space Telescope · gravitational-wave background.

Articles and further reading

Top recent videos

A short watchlist of recent explainers and documentaries on the universe.

Videos are embedded from YouTube and load only when you open a card.

Sources and further reading: Chronology of the universe (Wikipedia) · NASA Universe · ESA Planck. Times, temperatures and the visuals are rounded and illustrative; the observable universe is a horizon, not the whole universe.