The Last Thing That Will Happen in the Universe: Hawking Radiation, White Dwarfs and the Final Burst

This Kurzgesagt video takes you on a cosmic journey from the universe’s birth to its far future endgame. It explains how gas forms the first stars, how generations lock away material in red dwarfs, white dwarfs and black holes, and why the last meaningful event in the cosmos may be a final, galaxy-bright supernova before darkness returns.

• The cosmic gas budget and the birth of stars
• Gas locking by red dwarfs and remnants that slows new star formation
• The slow fade driven by white dwarfs cooling and black-hole evaporation
• A final, spectacular burst when a black dwarf collapses and lights up the universe one last time

Introduction

The video offers a sweeping, approachable account of the universe’s ultimate fate. It begins with the cosmos as a hot, dynamic place and then follows the gas that fuels star formation through billions of years of cosmic history. The focus shifts from birth to an increasingly quiet, gas-poor future, where remnants and black holes dictate what can form next and how long the lights might last.

Birth and the Gas that Builds Everything

Shortly after the big burst, the universe cooled into a sleepy, dark infancy, filled with swirling clouds of hydrogen and helium. The story of creation centers on this gas and where it ends up. As gas collapses under gravity, the first generation of stars lights up the cosmos, forging new elements in their cores and releasing many of them when they explode. The cycle of gas through successive stellar generations fuels galactic evolution, enriching gas with fresh elements for the next generation of stars.

Gas Cycling and the Stellar Population

Across generations, gas is repeatedly cycled through star formation. Yet not all gas is returned to the interstellar medium. Each new generation of stars tends to produce more red dwarfs, stars that burn slowly and live for trillions of years. When red dwarfs die, they are not strong gas contributors and instead become white dwarfs, locking up gas for ever. Other stellar remnants like neutron stars and black holes also trap gas, reducing the material available to form new stars. By the present era, most gas has already been captured or expelled, and over 90 percent of the stars that will ever be born have already come into being.

The Slow Fade and the Era of Red Dwarfs

Looking forward, the next few hundred billion years will be a period of exploration and gradual decline. Most large stars will die out, and red dwarfs will become the dominant stellar population. As gas becomes scarcer, star formation slows further, and the universe heads toward a slow, inexorable dimming.

The Long-Term Composition of Galaxies

In the distant future, about 10 percent of galactic mass remains as gas, while white dwarfs would comprise a large portion of stellar remnants. Neutron stars and black holes account for a few percent, while gas giants and brown dwarfs fill the rest. White dwarfs are dense, hot remnants roughly the size of Earth but with substantial mass, and they cool over extremely long timescales, becoming what is called a black dwarf as they lose their heat.

The Final Stages: Hawking Radiation and the Death of Black Holes

All objects in the cosmos gradually fade into darkness. Black holes slowly evaporate through Hawking radiation, with the last supermassive black hole dying after unimaginably long timescales. The idea is that even the darkest objects eventually vanish into a faint glow, leaving the universe in emptiness again, before a final transformative moment occurs.

The Last Interesting Event: The Black Dwarf’s Collapse

In the endgame, the physics inside a black dwarf leads to a dramatic, though incredibly distant, finale. If the remnant loses electrons to the point where it can no longer support its mass, it can undergo a catastrophic collapse, briefly erupting with a supernova that lights the cosmos as brightly as a galaxy. After this brief moment of light, the universe returns to darkness, truly dead on cosmic timescales beyond human comprehension.

Why This Matters for Us

The video emphasizes that while these timescales are fantastically far away, our current era is an optimal time to explore the cosmos. It invites curiosity and exploration, highlighting how the study of extreme physics and the fate of the universe can inspire questions about life, time and the nature of existence itself.

Conclusion

Today’s universe is a vibrant place for life and discovery, and the last interesting events are set far, far in the future. The message is a reminder of the grandeur of cosmic history and the importance of nurturing curiosity about science in the present.