Is the universe young?
The universe is 13.8 billion years old, yet the age of stars has 100 trillion years to run. Scaled to a human life, it is about five days old. The math.
By The Orbital Record editorial teamPublished Last reviewed
Yes. The universe is 13.8 billion years old, but stars will keep forming for about 100 trillion (1014) years and the last black holes will last to about 10100 years. If the age of stars were a 100-year human life, the universe today would be about five days old.
That is the long view this site is built on. We live in the Stelliferous Era, the age of stars, near its very beginning. Below is the arithmetic, step by step, and the honest counterarguments. For the full timeline, see our guide to the future of the universe.
How old is the universe?
The universe is 13.787 ± 0.020 billion years old, according to the Planck 2018 cosmological parameters. Planck mapped the cosmic microwave background, light released about 380,000 years after the Big Bang, and the standard model of cosmology turns those maps into an age. We use 13.787 billion years in every calculation below.
The universe as a human lifetime: the math
The comparison needs a yardstick for the universe’s “lifespan”. The natural one is the Stelliferous Era, which Fred Adams and Gregory Laughlin defined in their 1997 review “A dying universe”. They found that galaxies run out of gas and the smallest stars burn out at roughly the same time, so that essentially all normal star formation ends by cosmological decade 14: 1014 years after the Big Bang.
Now compress those 1014 years into a 100-year human life:
- Fraction of the era that has passed: 13.787 × 109 ÷ 1014 = 1.3787 × 10-4, or about 0.014%.
- Same fraction of a 100-year life: 1.3787 × 10-4 × 100 years = 0.013787 years.
- Convert to days: 0.013787 × 365.25 = 5.04 days.
- Convert to hours: 5.04 × 24 ≈ 121 hours.
On this scale, the universe is a five-day-old baby. Everything we know, from the first galaxies to the formation of the Sun 4.6 billion years ago, fits in its first week.
Stretch the yardstick to the whole known future, to the evaporation of the last black holes around 10100 years, and the result stops being intuitive:
- Fraction passed: 13.787 × 109 ÷ 10100 = 1.38 × 10-90.
- As part of a 100-year life: 1.38 × 10-88 years, or 4.35 × 10-81 seconds.
- The Planck time, the shortest interval current physics can describe, is 5.39 × 10-44 seconds. Our 4.35 × 10-81 seconds is about 1037 times shorter.
Young compared with what?
The answer depends on the yardstick, so here are five, each scaled to a 100-year life.
| Yardstick | Length | Universe’s age as a share | As a 100-year life |
|---|---|---|---|
| Lifetime of a Sun-like star | About 10 billion years | 138% | Already past it |
| Lifetime of the smallest red dwarf (0.08 solar masses) | About 12 trillion years | 0.11% | About 42 days |
| Stelliferous Era (age of stars) | 1014 years | 0.014% | About 5 days |
| End of the Degenerate Era | About 1039 years | 1.4 × 10-27% | About 4 × 10-20 seconds |
| Evaporation of the last black holes | About 10100 years | 1.4 × 10-88% | About 4 × 10-81 seconds |
The first row is the honest exception: by the clock of a star like the Sun, which burns hydrogen for about 10 billion years, the universe is already old, and many Sun-like stars born early have died. The red dwarf figure comes from stellar models by Adams, Laughlin and Graves (2004), which find that a star of 0.08 solar masses burns for about 12 trillion years.
Most stars have barely started
The strongest argument is not about clocks but about stars. Red dwarfs are the most common stars, and they live for trillions of years. Adams and Laughlin estimated that about 80% of all stars formed so far have not yet evolved significantly. In 2004, Adams, Laughlin and Graves put it in star-years: counting how long each star will shine, the galaxy has used up only about 0.1% of its total stellar lifetime.
In the 1997 paper’s own words, “if we use a linear time scale, the current epoch lies very near the beginning of the stelliferous era.”
The logarithmic clock: are we in the middle?
There is a second way to measure time, and it gives a different answer. Adams and Laughlin count time in cosmological decades, η = log10(age in years). Today η = log10(1.3787 × 1010) ≈ 10.14.
- Within the Stelliferous Era (η = 6 to 14), we are at (10.14 − 6) ÷ 8 ≈ 52%: right in the middle.
- From the Planck time (η ≈ −50.8) to 10100 years (η = 100), we are at (10.14 + 50.8) ÷ 150.8 ≈ 40%.
So on a logarithmic clock the universe is middle-aged. Which clock is “right”? Both are honest. The logarithmic clock is how physicists organize processes that span huge ranges, and it is generous to the early universe: the stretch from the Planck time to the end of the first second covers about 43 cosmological decades, while everything from that first second to today covers about 17.6. But stars burn, planets form and life evolves in ordinary years. In the units in which things happen, almost everything lies ahead.
The counterargument: star formation is past its peak
The universe’s most productive years are behind it. The cosmic star-formation history compiled by Piero Madau and Mark Dickinson shows that the rate of star birth peaked about 3.5 billion years after the Big Bang and has declined exponentially since, falling by a factor of e every 3.9 billion years.
So the fairest summary is: the universe is young but has already passed its most fertile youth. New stars are rarer, yet the small, long-lived stars already made will keep shining for trillions of years.
There is a second, stranger sense in which “now” is special. Lawrence Krauss and Robert Scherrer showed in 2007 that within about 100 billion years accelerating expansion will push every other galaxy out of view, erasing the evidence for the Big Bang. We live early enough to see where we came from.
Why it matters
Calling the universe young is not a slogan. It changes how you read the night sky: the stars you see are the opening act, and most of the light the cosmos will ever make has not yet been emitted. It also frames the open questions, from the nature of dark energy, which decides how the story ends (see Big Rip vs Big Crunch vs Big Freeze), to whether life is common in an era of stars that has barely begun.
You can scroll the full timeline, one power of ten at a time, in our Deep Time explorer, starting from the Stelliferous Era we live in.
Questions people ask
Is the universe young or old?
Young, measured in years against its own future. The universe is 13.8 billion years old, but stars will keep forming for about 100 trillion years and black holes will last around 10100 years. On that scale, the universe has lived about 0.014% of the age of stars alone.
How old is the universe?
About 13.8 billion years. The most precise value, 13.787 billion years with an uncertainty of 20 million years, comes from the Planck satellite's maps of the cosmic microwave background, analyzed with the standard model of cosmology and published in 2018 and 2020.
If the universe were a human, how old would it be?
If the age of stars, about 1014 years, were a 100-year human life, the universe today would be about five days old, roughly 121 hours. If the whole future to 10100 years were a 100-year life, the universe would have existed for far less than the shortest meaningful unit of time.
What era of the universe are we in?
The Stelliferous Era, the age of stars. In the scheme of Fred Adams and Gregory Laughlin it runs from about 106 to 1014 years after the Big Bang. We are near its start in ordinary years, and near its middle on a logarithmic scale.
Is the universe past its prime?
In one respect, yes. The rate at which galaxies form new stars peaked about 3.5 billion years after the Big Bang and has fallen steadily since. But most stars are small red dwarfs that shine for trillions of years, so the great majority of starlight the universe will ever produce is still to come.