Are we missing a dimension of time?
Could "hypertime" help develop a theory of everything? Roger Highfield reports
A scientist has put forward the bizarre suggestion that there are two dimensions of time, not the one that we are all familiar with, and even proposed a way to test his heretical idea next year.
Time is no longer a simple line from the past to the future, in a four dimensional world consisting of three dimensions of space and one of time. Instead, the physicist envisages the passage of history as curves embedded in a six dimensionals, with four of space and two of time.
"There isn't just one dimension of time," Itzhak Bars of the University of Southern California in Los Angeles tells New Scientist. "There are two. One whole dimension of time and another of space have until now gone entirely unnoticed by us."
Bars claims his theory of "two time physics", which he has developed over more than a decade, can help solve problems with current theories of the cosmos and, crucially, has true predictive power that can be tested in a forthcoming particle physics experiment.
If it is confirmed, it could point the way to a "theory of everything" that unites all the physical laws of the universe into one, notably general relativity that governs gravity and the large scale structure of the universe, and quantum theory that rules the subatomic world.
In the quest for that all embracing theory, scientists have been adding extra dimensions of space to their equations for decades. As early as the 1920s, mathematicians found that moving up to four dimensions of space, instead of the three we experience, helped in their quest to reconcile theories of electromagnetism and gravity.
Today, theoreticians are studying a theory of everything called M-theory that adds yet another dimension, taking the total to 11: 10 of space and one of time.
Until now, they have been reluctant to meddle with time because it can lead to unexpected consequences, such as time travel.
Changing our picture of time from a line to a plane (one to two dimensions) means that the path between the past and future could loop back on itself, allowing you to travel back and forwards in time and allowing the famous grandfather paradox, where you could go back and kill your grandfather before your mother was born, thereby preventing your own birth.
Bars first found hints of an extra time dimension in M-theory in 1995 and, when he looked into it, discovered the grandfather paradox and other fears could be overcome by using a new kind of symmetry - a mathematical property to work out the relationship between the quantities of position and momentum. It is this symmetry that might help reconcile the two mighty pillars of 20th-century physics, quantum mechanics and relativity.
Simply adding an extra dimension of time doesn't solve everything, however. To produce equations that work with the new symmetry that describe the world accurately, an additional dimension of space is needed as well, giving a total of four space dimensions, he explained in the journal Physical Review D.
According to Bars, the familiar four dimensional world we see around us is merely a "shadow" of the six-dimensional reality, just as a hand makes many different shadows on a wall when lit from different angles.
Although we cannot experience the extra time dimension directly, we can effectively notice it through the different perspectives of the different "shadows".
In this sense, he points to already existing evidence of physical phenomena at both macroscopic and microscopic scales. Furthermore, he believes that more evidence for his theory could emerge next year, when particles are smashed together in CERN's Large Hadron Collider near Geneva, Switzerland to create hitherto unseen "supersymmetric" particles.
The work poses a question: is his proposal a mathematical fix, rather than a real physical entity?
Bars insists his extra dimensions are more than mathematical sleight of hand. "Absolutely not," he told New Scientist. "These extra dimensions are out there, as real as the three dimensions of space and one of time we experience directly."
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