FIVE WAYS THE UNIVERSE COULD END

We'd like to think that the universe will continue forever, but chances are, at some point it will cease to be. Here's how current thinking suggests the end may come to pass

- RICHARD EDWARDS

OVEREXPANSION

1 THE BIG RIP

Two of the biggest mysteries facing cosmologists today are dark matter and dark energy. Our models of the universe suggest dark matter exists, but we can't see it, and even if it's out there, we have no idea how it might interact with normal matter. Meanwhile, observations tell us that the universe is growing at an ever-increasing rate, but this is counter-intuitive – you'd expect the gravitational attraction between galaxies to keep this growth in check, or even pull them back together. Astronomers believe that dark energy is driving this expansion. As the galaxies move further apart, the gravitational force between them decreases. If this continues, the force exerted by dark energy would gradually overwhelm the force of gravity. Galaxies would fall apart, planets would leave the orbits of their stars and the planets themselves would disintegrate. This process would continue until the Big Rip, when the fundamental forces that hold the universe together would become obsolete and reactions would become impossible. The universe would be dead.

TOTAL CHAOS

2 HEAT DEATH