It has long been proposed that when our universe came to fruition, three dimensions of space and one dimension of time sprang forth from the big bang: the event that made everything we see around us - from the hydrogen and helium that fuse to make stars and help planets coalesce, to black holes and galaxies, and even our own existences - possible,
However, there has been some debate over the traditional belief that the universe didn't just manifest three dimensions of space and one of time. In fact, throwing a couple of extra dimensions into the mix actually solves several of the more tricky problems we're still working to make sense of within the framework of the standard model of physics.
So could our universe really have more than one dimension of time?
Put away your hat, make sure your restraints are secure, and hold on tight: This is going to be an interesting (and pretty complex) ride through physics.
Einstein is responsible for much of what we know about how the universe works on a macroscale. His theories of general and special relativity play a big role in shaping our understanding of physics as a whole, but string theory and quantum physics, which are very important to the discussion we are about to have, were still in their infancy when Einstein died. Since then, both have become fully fleshed hypotheses, but there are certain aspects of both that cannot be reconciled with Einstein's work. Before we get into all that fun stuff, what is a dimension, and how do we know they exist?
Let's start with the three dimensions we deal with in our everyday lives: they can be summarized as length, width, and height, A straight line would be considered one dimensional. It merely has length, but no thickness, and it can travel forever in both directions. Two-dimensional objects, for example, something flat like a circle, or a square, have width and height, but no depth or "thickness" to them. Anything that has length, width, and height is considered three-dimensional, Time, as we know, is the somewhat more elusive fourth dimension... hence why the fabric of the universe is formally called spacetime instead of just plain 'ole space.
This is where the discussion of string theory comes into play.
So, what is String Theory?
Traditional physics asserts that the universe is comprised of 3 spatial dimensions and one temporal dimension. The universe itself is mostly empty by volume, but what we can observe is thought to be only around 5 percent of "normal matter" (think protons, electrons. neutrons, quarks, etc.), roughly 27 percent is made up of something called dark matter, while the remaining 68 percent is attributable to a mysterious unknown force believed to be causing the universe to expand, known as dark energy.
String theory, in the simplest possible terms, tells us to imagine that the very fabric of the universe and everything in it is not composed of point-like particles, but rather, it is comprised of incomprehensibly tiny strings - much smaller than even the smallest atom.
These strings are vibrating at their own special frequencies, making it conceivable that what we perceive to be point-like particles are actually not particles at all, but strings so tiny, they are "just 10^33 centimeters long. Written the long way, that would be a decimal point followed by 32 zeroes and then a 1. Some have theorized that the length of a string would have the same ratio to the diameter of a proton as the proton has to the diameter of the solar system.
There are two different types of these strings: one is open and the other is closed - though both are too small to be observed by current technology. As the name suggests, open strings are like wavy lines that don't touch ends, whereas the opposite is true for closed strings - they form loops and do not have open ends.
However, in order for string theory to work, mathematics dictates that many additional dimensions of space and time must exist. Should we find proof of these other dimensions, and should the number of extra dimensions range from 10 to 26, it would not only change our very understanding of quantum physics, but we'd be one step closer to creating a cohesive and credible "theory of everything." One that would be in agreement with both quantum physics and macrophysics - like the forces of nature and gravity, which is no easy feat.
Could there be an extra dimension of time?
As per usual, a lot of these theoretical arguments circle back around to Einstein's work. Ignoring Einstein's belief time might simply be a really elaborate illusion, the question as to whether there could be additional dimensions of time is a firm maybe. In fact, through studying how the fundamental forces of nature and the laws of physics are affected by time, some astronomers believe that throwing in at least one extra dimension of time would solve one of the biggest remaining cosmological bugaboos.
You see, we still don't know exactly what gravity is, or how it fully affects matter seen and unseen. Our best guess, once again an Einsteinian theory, says that gravity is the force created by the warping of spacetime. The larger the object is, the more it warps the spacetime around it, and the stronger its gravitational pull becomes. That would be all well and good if we didn't have to marry our theories of gravity with quantum theory, but we do, and therein lies the problem.
Our current understanding of gravity is simply not consistent with other elements of quantum mechanics. The remaining forces of nature - the electromagnetic force and the strong and weak nuclear forces - all fit into the framework of the micro-universe, but not gravity. It is hoped that maybe string theory can help solve that mystery. At least one physicist argues that time isn't merely one-dimensional.
Itzhak Bars, a theoretical physicist from USC College, told NewScientist, “There isn’t just one dimension of time, there are two. One whole dimension has until now gone entirely unnoticed by us.”
He also described how extra dimensions of space could exist 'in plain sight' saying, "Extra space dimensions aren't easy to imagine — in everyday life, nobody ever notices more than three. Any move you make can be described as the sum of movements in three directions — up-down, back and forth, or sideways. Similarly, any location can be described by three numbers (on Earth, latitude, longitude, and altitude), corresponding to space’s three dimensions. Other dimensions could exist, however, if they were curled up in little balls, too tiny to notice. If you moved through one of those dimensions, you’d get back to where you started so fast you’d never realize that you had moved."
“An extra dimension of space could really be there, it’s just so small that we don’t see it,”
What Would Extra Dimensions of Time Mean?
Have you made it this far? Congratulations. The conclusion is worth wading through all these complicated ideas.
Physics mostly argues that time must be a dimension, but there are certainly physicists that believe time is just a human construct. Others argue there must be more dimensions of time than previously believed. What would that mean for physics, should this be true?
Well, for Bars, it would mean, "The green light to the idea of time travel. If time is one-dimensional, like a straight line, the route linking the past, present, and future is clearly defined. Adding another dimension transforms time into a two-dimensional plane, like a flat sheet of paper. On such a plane, the path between the past and future would loop back on itself, allowing you to travel back and forwards in time. That would permit all kinds of absurd situations, such as the famous grandfather paradox. In this scenario, you could go back and kill your grandfather before your mother was a twinkle in his eye, thereby preventing your own birth."
Two-dimensional time gives every appearance of being a non-starter. Yet in 1995, when Bars found hints in M-theory (a theory that unifies all consistent versions of superstring theory) that an extra time dimension was possible, he was determined to take a closer look. When he did, Bars found that a key mathematical structure common to all 11 of the posited dimensions in M-theory (10 dimensions of space and 1 of time) remained intact when he added an extra dimension. “On one condition,” says Bars. “The extra dimension had to be time-like.”
What do you think about string theory, quantum gravity, and extra dimensions of time?