Although in theory time can be divided into infinitely small intervals, the smallest physically meaningful interval of time is Planck time, which is approximately equal to 10 -43 seconds. This final limit means that the two events cannot be separated by a time that is less than this interval. But now, in a new work, physicists have come to the conclusion that the shortest physically meaningful time interval may in fact be several orders of magnitude longer than Planck's time. In addition, physicists have demonstrated that the existence of such minimal time changes the basic equations of quantum mechanics, and since quantum mechanics describes all physical systems on the smallest scale, it also changes the description of all quantum mechanical systems.
Scientists Mir Faisal of the University of Waterloo and the University of Lethbridge in Canada, Mohammed Khalil of the University of Alexandria in Egypt, and Sauria Das of the University of Lethbridge have published an article entitled "Time Crystals from Minimum Time Uncertainty" in the European journal Physical Journal C.
“It may be that in the Universe the minimum time scale is actually much longer than Planck's time, and this can be verified experimentally,” Faisal told Phys.org.
Planck's time is so short that no experiment has ever been close enough to test it directly - the most accurate tests can access a time interval of the order of 10-17 seconds.
Nevertheless, there is strong theoretical support for the existence of Planck's time in various approaches to quantum gravity, such as string theory, loop quantum gravity, and perturbative quantum gravity. Almost all of these approaches assume that it is impossible to measure length less than Planck's length, and in a broader sense, time is shorter than Planck's time too, since Planck's time is defined as the time it takes light to travel one unit of Planck's length in a vacuum.
Girdled with the latest theoretical studies, scientists looked into the question of the structure of time - in particular, touched upon the old question: is time discrete or continuous?
“In our work, we assumed that time is discrete in nature, and also suggested ways to experimentally test this assumption,” says Faisal.
One possible test involves measuring the rate of spontaneous emission of a hydrogen atom. The improved quantum mechanical equation predicts a slightly different rate of spontaneous emission than predicted by the conventional equation, within a range of uncertainty. The proposed effects can also be observed in the decay rate of particles and unstable nuclei.
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Based on their theoretical analysis of spontaneous hydrogen emission, the scientists estimate that the minimum time interval should be several orders of magnitude longer than Planck's time, but not more than a certain value established by previous experiments. Further experiments can lower this limit of the minimum time or determine its exact value.
Scientists also speculate that the proposed changes to the basic equations of quantum mechanics could change the very definition of time. They explain that the structure of time can be seen as crystalline, consisting of discrete, regularly repeating segments.
On a more philosophical level, the discrete time argument means that our perception of time as something constantly flowing is just an illusion.
“The physical universe is really like a picture in a movie, with a series of still images creating the illusion of moving images,” Faisal says. "So, if we take this point of view seriously, our conscious perception of physical reality, based on continuous movement, will become an illusion produced by the discrete mathematical structure underlying time."
“This proposal makes physical reality platonic in nature,” he says, pointing to Plato's argument that true reality exists independently of our senses. "Nevertheless, unlike other theories of Platonic idealism, our proposal can be tested experimentally and can be attributed not only to philosophy."
