Traveling in Time
Most of us have dreamed of traveling through time, backward or forwards, faster than those around us. And surprisingly, recent work has shown us that time travel is far more than just a dream. In fact, a number of researchers have explored, and are currently exploring, the legitimacy of time travel. While they haven't quite gotten to the point where they are able to time travel themselves—these researchers have found some concrete science backing it up.
This past June, I met with James Beacham, a particle physicist at the European Organization for Nuclear Research (CERN), at Brain Bar Budapest, a festival focused on the future, to talk about the ways in which time travel has enraptured humanity and discuss both the logistical and technical potential of time travel.
Beacham began by outlining the ways that, according to Einstein's theories, time travel is technically possible through a number of different methods.
"If space can be bent, then spacetime can be bent."
One proposed method of time travel is via wormholes. “We know that space can be bent. If space can be bent by, say, gravity, then spacetime can be bent," Beacham said. To clarify, space is the three-dimensional body in which all things in the universe move. Spacetime, however, is the combined concepts of space and time into a four-dimensional continuum. You may have even seen spacetime portrayed as a fabric, manipulated by energy. If spacetime can be bent, Beacham continued, it's theoretically possible that time can be bent.
Making Time Travel A Reality
This concept of bending spacetime sprung from Einstein’s theory of General Relativity, which introduced the idea that wormholes could, in theory, act as a bridge between two points that would otherwise be very distant. Because of spacetime's flexibility, a wormhole could link two different points in its fabric.
Recently, evidence for this theory has moved beyond the strictly theoretical. A couple of years ago, scientists built what they described as a "wormhole." Their model, however, created a portal for magnetic fields. As Smithsonian outlined, "if another magnetic field travels through the wormhole, it appears to leave space altogether, only showing up at either end."
So it doesn't exactly teleport particles (or people) across spacetime, but it does highlight the continual advances that are being made in our ability to manipulate the various fundamental forces in our universe, and ultimately, the manipulation of this force is an important step towards creating a simplified wormhole that would allow us to send electromagnetic waves through an invisible tunnel. Perhaps, one day, we will be able to manipulate spacetime in a similar manner.
So while wormholes remain theoretically possible and important steps are being made, wormholes in spacetime, specifically, have yet to be observed or created.
Another potential method of time travel is time dilation. Einstein's theories predicted that time passes differently throughout the universe. We now know this to be true—clocks tick slower on the International Space Station (ISS) than they do here on Earth, for example. This happens because time moves slower for objects that are near strong gravitational fields (such as Earth) than for objects further from these fields, like the ISS.
So by spending time off Earth's surface and returning at a later point, a human could, in a sense, fast forward through time. If you could get close to a black hole, because there are such strong gravitational forces in the vicinity, time would slow to a mesmerizing degree. Thousands of Earth-years might pass by while only a few seconds tick by near a supermassive black hole.
Time dilation also comes into play where speed is concerned. If we were to, say, travel at 95% of the speed of light, time would slow down dramatically. So again, thousands of Earth-years could pass by in what the traveler experiences as just a few moments.
And this is just the beginning, as there are a number of different ways in which we could make time travel into a reality. Scientists from various disciplines are investigating different methods for us to make more dramatic jumps through time, like using circulating light beams, which can be created through the use of gamma and magnetic fields to twist space and cause time to be twisted. Other methods include quantum tunneling and hypothetical cosmic strings.
Of course, just because something is theoretically possible doesn't mean it's technically feasible. At least, not yet. We can't make wormholes, and we can't travel near the speed of light. But there is hope that we could achieve these things in the very near future. "We could possibly address things about time travel and understand the basic nature of time with the research that we do now. Or at least, in the next 50 to 100 years," Beacham said.
Yet, we must acknowledge the possibility that moving back and forth through time may be contrary to the laws of physics. Still, that doesn't mean we shouldn't try. As Stephen Hawking famously wrote in his autobiography, "Even if it turns out that time travel is impossible, it is important that we understand why it is impossible."