In Einstein's equation, time is a river. It speeds up, meanders

In the words of Michio Kaku: “In Einstein's equation, time is a river. It speeds up, meanders, and slows down. The new wrinkle is that it can have whirlpools and fork into two rivers. So, if the river of time can be bent into a pretzel, create whirlpools and fork into two rivers, then time travel cannot be ruled out.” This is not merely the language of science; it is the language of myth reborn in the age of equations. It is the voice of the modern sage, drawing upon the discoveries of Einstein and clothing them in the imagery of flowing waters, so that mortals may grasp the vastness of eternity.

To say that time is a river is to echo the wisdom of the ancients. Heraclitus declared, “You cannot step into the same river twice,” for both the river and the man are changed. Kaku extends this image into the cosmic, revealing that time itself—once thought rigid and absolute—flows, bends, and turns as water does through valleys and mountains. It is no longer the stern clock of Newton, ticking with cold indifference, but a living, breathing current that carries us toward the unknown.

And yet Kaku speaks of more than meandering. He speaks of whirlpools and forks, of the possibility that time may spiral upon itself or divide into twin currents. This is a vision that borders upon the mythic, where mortals may step across to another stream of destiny, or find themselves caught in the vortex of what might have been. To imagine time as a river with whirlpools is to accept that the past may circle back upon itself, and to imagine its forking is to consider the existence of parallel lives, universes alongside our own. What the poets once dreamed, the physicists now dare to contemplate.

History, too, gives us echoes of this yearning. Think of Augustine of Hippo, who wrestled with the mystery of time, declaring it a distension of the soul, where past, present, and future coexist within memory and anticipation. Augustine felt time’s river within himself, though he had no Einstein to guide him. Centuries later, Einstein would bend the heavens themselves, showing that time quickens near massive stars and slows in the emptiness of space. The eternal question that haunted Augustine—the nature of time—was given new flesh by relativity, and new imagination by Kaku’s metaphor.

But let us not dismiss time travel as mere fantasy. Consider the explorers who, by voyaging across the globe, seemed to cheat time itself. When Magellan’s surviving crew returned to Spain after circling the earth, they found themselves a day ahead of those who had stayed behind. By sailing eastward into the dawn, they had bent their personal river of time, showing that even without machines, the flow of hours can be altered. What greater wonders may lie ahead, when humanity wields the full power of physics, and the river is bent as Kaku envisions?

The lesson is not only about machines or science—it is about perspective. Time is not fixed, and neither are you. Just as the river can bend and fork, so too can your life. You are not trapped in one destiny; your choices carve new channels, your will creates new streams. To believe in whirlpools of time is to believe that even the past may be revisited—not by machines, perhaps, but by memory, by reflection, by the stories we tell and retell, which allow us to step once more into the waters we thought were gone.

Therefore, the teaching is this: live as though time is alive. Do not treat it as a tyrant that marches forward without mercy. Treat it as a river, to be navigated with skill, patience, and courage. Watch for its currents; do not fight them blindly, but steer your vessel with wisdom. Travel widely, think deeply, and remember that even when you feel trapped in one course, there may be forks unseen, whirlpools yet to be discovered, new channels waiting for your spirit to find them.

So, future generations, hear this: from Einstein to Kaku, the sages remind us that time is not a prison but a mystery. If the river of time can bend, then so too can the course of your destiny. Do not drift like a leaf upon the stream—be the navigator, the helmsman, the voyager of your own hours. And if one day humankind bends the river into loops and whirlpools, remember that the first time-travel is already in your hands: the power to shape the future by how you live in the present.