The Many Faces of Time: From Glass Molecules to Dying Stars

Courtesy: Hashem Al-Ghaili

Time travel has long captured the imagination of scientists, storytellers, and dreamers alike. The ability to jump backward or forward through time raises tantalizing possibilities: revisiting historical moments, correcting past mistakes, or even glimpsing the far future. But if you ever manage to invent a working time machine, there’s a much bigger challenge waiting for you, and it’s one you might not have considered.

Even if you perfectly crack the code of traveling through time, you might find yourself stranded, not in the past or future, but in the empty void of space.

At first glance, it seems logical that traveling back to yesterday would mean arriving in the exact same spot, just 24 hours earlier. But our universe doesn’t work that way. That’s because Earth, and everything on it, is in constant motion.

Let’s break this down.

First, Earth rotates on its axis. Every 24 hours, our planet completes one full spin, moving points on the equator at about 1,600 kilometers per hour (1,000 mph). This rotation gives us day and night.

But it doesn’t stop there. Earth is also orbiting the Sun at an incredible 107,000 kilometers per hour (66,600 mph). This journey around the Sun takes a full year to complete.

And that’s just the beginning. Our entire solar system is flying through space, spiraling around the center of the Milky Way galaxy at a speed of about 828,000 kilometers per hour (514,000 mph). That galactic orbit will take roughly 230 million years to finish just one lap.

Now, imagine you set your time machine to travel back a few hours. If your machine only adjusts the time but not your position, you won’t land on the surface of Earth. In fact, Earth will have moved thousands of kilometers by the time you “arrive.”

Instead of stepping out of your machine and into your familiar surroundings, you’d materialize in the middle of deep space, probably suffocating and freezing in moments.

To put it simply, time travel without spatial adjustment equals disaster. In order to safely move through time, you'd need to calculate and replicate Earth’s exact location, speed, and orientation in the universe for that specific moment.

And that’s an incredibly complex problem.

To make matters even trickier, scientists are still working on understanding the very fabric of our universe. One of the most puzzling mysteries today is something known as the Hubble Tension, a discrepancy in how fast our universe is expanding.

Recent measurements of a galaxy cluster known as the Coma Cluster have intensified this mystery. Using the Cosmic Distance Ladder Method, astronomers observed light from 12 Type Ia supernovae, exploding stars with reliable brightness. These supernovae serve as "cosmic mile markers," helping scientists measure distances across vast cosmic scales.

Their findings resulted in a highly accurate calculation of the Hubble Constant, the rate at which the universe is expanding. But here’s the twist: this local measurement doesn’t match predictions based on early universe models and data from the Big Bang.

This mismatch suggests that our current understanding of physics may be incomplete. It could point to undiscovered forces, particles, or flaws in our cosmological models. And if we don’t fully understand the universe’s behavior, then tracking its motion for precise time travel becomes even more daunting.

Amid these cosmic uncertainties, one theory continues to stand tall: Einstein’s general theory of relativity. For over a century, this theory has been our best explanation of gravity, time, and space.

And it just passed one of its biggest tests yet.

Astronomers recently examined how galaxies cluster and form a vast “cosmic web” over 11 billion years of cosmic history. They used data from nearly 6 million galaxies, collected by the Dark Energy Spectroscopic Instrument (DESI), an advanced telescope system that’s been operational since 2019.

The study showed that the behavior of these galaxy clusters closely matches what Einstein’s theory predicted long ago. This confirms that general relativity remains accurate not just on small scales, like planetary motion, but across the vast expanse of the universe.

Even after zooming out to cosmic proportions, the same rules of gravity still apply. It’s like Einstein wrote the universe’s rulebook, and billions of years later, the universe is still playing by those rules.

In the coming years, DESI will map out over 40 million galaxies and quasars, giving scientists more data than ever before. This could help us finally unravel the secrets of dark matter and dark energy, the mysterious substances that make up most of the universe but remain poorly understood.

Until then, time travel, at least the kind we imagine in science fiction, remains out of reach. Even if you master the technology, you’d need to calculate and compensate for the incredible velocities and movements of Earth, the solar system, and the galaxy.

Otherwise, your journey through time could end with you floating helplessly in space, far from home.