The Science of Time

The Science of Time: How We Know, Count, and Travel Through It Time is probably the most mysterious and fundamental aspect of our universe. We exist with it, divide our days within it, and age due to it. And yet, despite its omnipresent presence in our lives, time remains one of the most bewildering subjects in science. What is time, and how does it operate? Can time be bent, stretched, or even reversed? In this article, we'll be going over the science of time, how it's measured, and if it's really possible to travel through time. What Is Time? Essentially, time is a way of talking about changing things. It allows us to distinguish between the past, present, and future. Yet in science, time is not merely a product of our imagination—it's a part of the fabric of the universe itself. Spacewise, time is the fourth dimension. Besides space's three dimensions—length, width, and height—time makes up what physicists call spacetime. Albert Einstein developed this in his General Relativity theory. According to this theory, space and time are inseparable, and the presence of mass (like stars or planets) can warp spacetime, including the passage of time. This warping produces what is referred to as gravitational time dilation. Essentially, time moves more slowly near heavy objects. So theoretically, if you were located beside a black hole, time for you would move more slowly than for an individual living on Earth. This isn't something from science fiction—this has actually been measured and confirmed using precise atomic clocks. How Do We Measure Time? Human beings have been obsessed with keeping time for centuries. From the sundials of ancient Egypt to atomic clocks in the contemporary world, our time-measuring devices have seen a revolutionary transformation. Ancient Methods Natural occurrences were used by ancient human societies to keep time. The sun, moon, and stars' movement led human beings to measure days, months, and years. Water clocks and hourglasses gave some precision, but they were still very limiting. Mechanical Clocks Mechanical clocks, which used gears and weights to offer a more precise measurement of time, emerged in Europe in the 14th century. They revolutionized timekeeping. Atomic Clocks The standard of gold in the modern era is the atomic clock, which bases time on the vibrations of atoms (usually cesium or rubidium) with unmatched precision. These clocks are so accurate that they would lose or gain only a second every few million years. Atomic time now serves to define the SI second and powers everything from GPS satellites to the internet. The Arrow of Time Perhaps the most fascinating fact about time is that it seems only to move in one direction—forward. We remember the past, and not the future. A broken glass won't unbreak. It is called the arrow of time when we move in this direction. The flow of time has a great deal to do with the concept of entropy, which stems from the second law of thermodynamics. Entropy is a measure of disorder in a system. The universe's entropy always increases, as stipulated in this law. This implies that systems naturally evolve from order to disorder, and this gives the direction of time. Time moves forward because the universe is becoming more disordered. Can We Travel Through Time? This is the question that tickles everyone's imagination. Is time travel possible? According to current physics, the answer is: perhaps—but with fairly strict limits. Time Travel to the Future Time travel to the future is not only possible—it has already happened, thanks to Einstein's relativity theory. Astronauts on the International Space Station actually pass through time a fraction of a second more slowly than humans on Earth because they are in motion and experiencing a weaker gravitational pull. It's an extremely tiny effect, but it is measurable. This is called time dilation. If a human being would travel nearly at light speed, time would near stand still for him compared to humans on Earth. When he returns, he will notice that more time has passed for all others. This is the twin paradox and is fully accepted in theoretical physics. Time Travel to the Past Traveling back in time, however, is a much greater challenge. It creates paradoxes, such as the famous "grandfather paradox" (what if you travel back and prevent your grandfather from getting together with your grandmother?). Although theoretically suggested solutions, including wormholes and cosmic strings, have been presented, these are conjectures and most likely impossible under the laws of physics that exist at our current level of understanding. Why Time Matters Understanding time is not a matter of intellectuals—it has real-world application. GPS satellites, for example, need to account for both their speed and Earth's gravitational field causing time dilation. GPS systems would lose their accuracy very quickly if they did not apply these relativistic adjustments. Time is also important in quantum mechanics and cosmology, and even in biology. The internal biological clock of our body controls sleep, digestion, and hormones through the circadian rhythms. Disturbing this rhythm, like that produced by jet lag or night shifts, can trigger dire diseases. Interesting Facts About Time The largest time measurement is the cosmological decade, an astronomical measurement spanning ten times the age of the universe. The Planck time is the smallest unit of significant time—approximately 5.39 × 10 − 44 5.39×10 \ −44 seconds. There are even some quantum theories suggesting that time may not be fundamental after all—it could be an emergent effect of more basic laws. In 1971, physicists flew atomic clocks on ordinary planes around the globe and confirmed time dilation as predicted by relativity. Final Thoughts Time is a secret that is at the heart of our understanding of the universe. From the tick of a clock to the expansion of space itself, time controls everything. And yet, despite all we have learned about how time works, much is still a mystery. Could time reverse under certain conditions? Does there exist a single, universal "now"? Will advancing technologies allow us to travel through time as easily as we travel through space? For the moment, time keeps moving—unyielding, enigmatic, and eternally captivating.