Parallel Worlds

The Big Bang and the Idea of the Multiverse

For centuries, human understanding of existence was divided between two conflicting ideas. One perspective, common in many Western traditions, suggests the universe had a specific moment of creation. The other, found in various Eastern traditions, views the universe as timeless, with no beginning or end. As a child, Michio Kaku felt this tension while attending both Buddhist and Christian services, finding the dramatic stories of sudden creation stood in direct opposition to the concept of an eternal, meditative state. Modern science is now revealing that these seemingly contradictory ideas may both be true.

A new generation of scientific instruments suggests our specific universe began with a Big Bang, but it may exist as one of many bubbles floating in a vast, eleven-dimensional ocean. In this view, creation events are happening all the time. While our universe has a definite starting point, the larger arena in which these universes form—the multiverse—could be timeless. This synthesis allows for the sudden birth described in ancient myths to occur repeatedly within a permanent, unchanging background.

The most significant evidence for this new understanding comes from the Wilkinson Microwave Anisotropy Probe (WMAP) satellite. Launched in 2001, this instrument captured the faint afterglow of the Big Bang, radiation emitted only 380,000 years after the universe began. Because light takes time to travel across space, looking at the night sky is effectively looking back in time, and WMAP provided a detailed baby picture of the cosmos. This data has transformed cosmology from a field of speculation into a precise science, allowing researchers to determine that the universe is 13.7 billion years old.

The WMAP data also revealed a surprising truth about the universe's composition. Visible matter—stars, planets, and people—makes up only 4 percent of the cosmos. The rest is composed of mysterious substances that do not emit light. About 23 percent is dark matter, an invisible material that exerts gravity and holds galaxies together. The remaining 73 percent is dark energy, an unknown form of energy in empty space that acts as a kind of antigravity, pushing the universe apart at an accelerating rate.

To explain how the universe became so large and uniform, scientists rely on the theory of inflation. This theory proposes that in the first trillionth of a second after the Big Bang, a powerful force caused the universe to expand much faster than the speed of light. This explosive growth smoothed out the fabric of space, explaining why the universe looks the same in every direction. If we imagine the universe as a balloon being inflated, the part we can see with our telescopes is just a tiny patch on its surface. The actual universe is likely much larger than the visible one.

This inflationary process might not be a one-time event. Some physicists suggest the mechanism is still active, with tiny patches of space suddenly inflating to create new baby universes that bud off from their parents. This leads to a picture of a never-ending cycle of creation, where universes are constantly being born like bubbles in boiling water. This multiverse theory suggests our universe is just one member of a vast collection, each perhaps with its own unique laws of physics. The theoretical framework supporting these ideas is known as string theory, or its more advanced version, M-theory. It suggests the fundamental building blocks of the universe are not particles, but tiny vibrating strings or membranes in eleven dimensions. Just as different vibrations on a violin string create different musical notes, the vibrations of these strings create the various subatomic particles we observe. In this sense, the laws of physics are the harmonies governing the music of these strings.

While these theories explain the beginning of the universe, they also provide a grim forecast for its end. Because dark energy is causing the expansion to speed up, galaxies are moving away from each other faster and faster. Eventually, the night sky will grow dark as distant galaxies move beyond our sight. Billions of years from now, stars will run out of fuel, leading to a state called the Big Freeze. In this future, the universe will become so cold and dilute that life as we know it will become impossible as the temperature approaches absolute zero. Faced with this eventual death, intelligent civilizations might look for ways to survive, perhaps by creating a gateway to a younger, warmer universe within the multiverse or by transmitting the essential information of their culture through a portal to be rebuilt on the other side.