That all changed when the universe exploded 13.8 billion years ago. Rapid inflation divided a single “super” force into the four fundamental forces we know today: gravity, electromagnetic ...

Of the four known fundamental forces of nature, the weak nuclear force ... electromagnetic forces, and between the four particles that carry them. But this symmetry was unstable. As the universe ...

The rest of the universe appears to be made of a mysterious, invisible substance called dark matter (25 percent) and a force that repels ... light and other forms of electromagnetic radiation ...