The concept of time as a way to measure the duration of events is not only deeply intuitive, it also plays an important role in our mathematical descriptions of physical systems. For instance, we define an object’s speed as its displacement per a given time. But some researchers theorize that this Newtonian idea of time as an absolute quantity that flows on its own, along with the idea that time is the fourth dimension of spacetime, are incorrect. They propose to replace these concepts of time with a view that corresponds more accurately to the physical world: time as a measure of the numerical order of change.
In two recent papers (one published and one to be published) in Physics Essays, Amrit Sorli, Davide Fiscaletti, and Dusan Klinar from the Scientific Research Centre Bistra in Ptuj, Slovenia, have described in more detail what this means.
No time dimension
They begin by explaining how we usually assume that time is an absolute physical quantity that plays the role of the independent variable (time, t, is often the x-axis on graphs that show the evolution of a physical system). But, as they note, we never really measure t. What we do measure is an object’s frequency, speed, etc. In other words, what experimentally exists are the motion of an object and the tick of a clock, and we compare the object’s motion to the tick of a clock to measure the object’s frequency, speed, etc. By itself, t has only a mathematical value, and no primary physical existence.
This view doesn’t mean that time does not exist, but that time has more to do with space than with the idea of an absolute time. So while 4D spacetime is usually considered to consist of three dimensions of space and one dimension of time, the researchers’ view suggests that it’s more correct to imagine spacetime as four dimensions of space. In other words, as they say, the universe is “timeless.”
“Minkowski space is not 3D + T, it is 4D,” the scientists write in their most recent paper. “The point of view which considers time to be a physical entity in which material changes occur is here replaced with a more convenient view of time being merely the numerical order of material change. This view corresponds better to the physical world and has more explanatory power in describing immediate physical phenomena: gravity, electrostatic interaction, information transfer by EPR experiment are physical phenomena carried directly by the space in which physical phenomena occur.”
As the scientists added, the roots of this idea come from Einstein himself.
“Einstein said, ‘Time has no independent existence apart from the order of events by which we measure it,’” Sorli told PhysOrg.com. “Time is exactly the order of events: this is my conclusion.”