How Did Time Start And How Will It End? | Unveiled

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When Did Time Start and How Will it End?</h4>

Time is one of the greatest mysteries of the universe. Events move in a sequential string, flowing from the past, into the present, and gliding into the future. For millennia, we have built our lives around the transitions between day and night, and from season to season. Human beings first started to measure time in around 1,500 BCE using sundials in ancient Babylon and Egypt. But we only measure time, we didn’t invent it. 

This is Unveiled, and today we’re answering the extraordinary question: When Did Time Start and How Will it End?

From our perspective, time is an arrow that flies in one direction. Cause and effect exist in a seemingly irreversible sequence from past to future. We can remember the past but, with the exception of alleged seers and soothsayers, cannot remember times yet to come. Ancient Greek philosophers endlessly debated the origins of time. Aristotle defined it as movement and change. He argued that it could not have had a beginning, because for something to begin, there would have to have been a time beforehand when it didn’t exist - which is self-contradictory. Later, Christian theologians tackled the issue and came to the opposite conclusion. St. Augustine believed in a God that superseded space and time. A truly infinite Creator like the Christian God could create existence and time out of the void. When considering what God did before the first day, Augustine replied that since God created time, there simply was no before. 

Hundreds of years later, Albert Einstein pushed the debate forward with his theory of special relativity. He discovered that time is relative to the observer. For example, if two observers are moving relative to one another, the one who’s moving at a higher velocity will experience time as passing more slowly. So if you launched off in a spaceship at high speeds, and returned to Earth, less time will have passed for you than for everyone else back home. The more one accelerates towards the speed of light, the more pronounced this time dilation gets. Using decades of space observations, physicists then built on Einstein's work, tracing the origins of the universe back to an infinitely dense point known as the singularity. 

The universe as we know it expanded in an event colloquially called “The Big Bang”, a period of rapid cosmic inflation. And so, according to this theory, time began at the same time as our universe did - between 13.7 and 13.8 billion years ago. As such, the Big Bang has generally been considered to be the likely source of both the universe and time for almost a century. And asking ‘what came before the Big Bang’ is like asking “what’s south of the South Pole.” We lack an adequate frame of reference to answer the question. Even the famed physicist Steven Hawking dismissed the question’s relevance in his book “A Brief History of Time.” He contended that even if time existed before the Big Bang, there is literally no information from that timeframe to observe. It would have no effect on the universe as it exists now and therefore the problem is effectively meaningless. 

But that may no longer be an entirely accurate assessment. As technology advances, astronomers and cosmologists are able to take ever more detailed measurements of the cosmos. Today, we’ve learned that extrapolating backwards to a singularity may be the wrong approach. Since the 1980s, scientists have been able to take incredibly accurate readings of the cosmic microwave background radiation (the CMB) - the afterglow of the Big Bang itself. The patterns and magnitudes of fluctuations in the CMB can act as both cartographer and historian of the universe. One of the many things we can extrapolate from cosmic radiation was whether or not there was a maximum temperature in the early stages of the universe. According to data accrued by NASA’s Wilkinson Microwave Anisotropy Probe and ESA’s Planck space observatory, there was a temperature cap. Their observations indicate that the Universe never reached a temperature higher than 1029 K.

Why does that matter? What does that have to do with time? While 1029 K is very hot, it is more than 1,000 cooler than the temperatures equated with a singularity. And that casts into doubt whether we can extrapolate from the Big Bang to a singularity. Moreover, it tells us that there actually may have been a “before the Big Bang” after all. So what could have caused the rapid expansion of space that created our universe, instead? And wouldn’t the gravity of ordinary matter have slowed that expansion? 

Well, some physicists believe that this spurt of inflation was due to a quantum field containing a massive amount of potential energy. Potential energy, when compared to kinetic energy or rest mass, causes gravitational repulsion. This quantum field hit the gas on inflation and helped cause the Big Bang. There are two theories that account for this. One is called loop quantum gravity, which is linked to a cosmology in which the universe bounces between contraction and expansion. The other, which is more familiar to most people, is String Theory.

String Theory is an incredibly complicated notion. In short, it suggests that instead of point-like particles, the universe may actually be composed of one-dimensional strings. What we see as a particle is actually just a string vibrating with a unique frequency. And though String Theory began as an explanation for the interactions of particles like protons, it has now evolved into a potential ‘theory of everything’ - a unified theory of physics. 

Once particle theory makes way for vibrating strings, new properties appear and reveal interesting possibilities. And, with regards to time specifically, String theory proposes that the Big Bang was not the origin of our universe. Instead, it did come about as a result of what existed before. As the father of String Theory, Gabriele Veneziano, put it in Scientific American, “String theorists expect that when one plays the history of the universe backward in time, the curvature of spacetime starts to increase. But instead of going all the way to infinity (at the traditional big bang singularity), it eventually hits a maximum and shrinks once more.” 

In this scenario, it may be the case that the Bing Bang wasn’t the ‘beginning’ of time. Instead, it may just represent an immeasurably energetic transition from acceleration to deceleration. In Veneziano’s Pre-Big Bang scenario, “the pre-bang universe was almost a perfect mirror image of the post-bang one.” This means that if our future spills out into infinity, so does our past.  Which then means that here is no beginning of time, and no end.

But this is entering territory where physics, as it currently stands, fails us. The nature of inflation wipes out what happened during its earliest stages, leaving us without any data to go by. As of now, we are only able to make educated guesses at the origins of time. 

Is there such a thing as time’s end, however? In some ways, the continuation or cessation of time is relative to your place in the universe; for example, time needn’t perish everywhere, all at once. There may therefore already be places in our universe where time has ceased. According to relativity, for example, the time dilation of a hyper massive black hole could get so extreme at its core that time may well expire altogether. All the while it marches on and on outside of it.

So, finally, when it comes to the question of “will time end everywhere?” we similarly enter the realm of speculation depending on the possible Ultimate Fate of the Universe. Some researchers in the field of quantum gravity believe that time stretches on infinitely, with neither beginning nor end. The universe, they say, always was and always will be, with events like the Big Bang just marking massive transitions. Others point to possible endings of the universe as marking the end of time as well. Based on the universe’s rate of expansion and mass, many scientists believe that it will continue to expand forever - leading to heat death, or a ‘Big Freeze’. In this scenario, we could see time slowly lose its properties. The Oxford physicist Roger Penrose, in his book Cycles of Time: An Extraordinary New View of the Universe, paints a picture reminiscent of Salvador Dalí’s Persistence of Memory. Though you could tell the chronology or order of events, duration would lose meaning. Time, like matter, would expand infinitely until it essentially vanished altogether. Then again, while it isn’t the favored theory, if there is enough mass in the universe to eventually slow and stop its expansion, it could end in a Big Crunch - collapsing into a new hot, dense state. If so, a Big Bounce could be what follows next, resulting in time ceasing and restarting… much as it may have with the Big Bang all of those years ago.

Theologians and philosophers have debated the origins and nature of time for thousands of years. Science and cosmology eventually came along to support or debunk those notions. Is time an arrow that flies in one direction? If so, does it eventually hit a target or does it fly forever? Or is time a cycle that starts and stops with the birth and death of a universe? We don’t have a definitive answer and may never find one. But theoretical physics has come a long way over just the last century; many hope that we may develop the answers in time.