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An international group of researchers including Russian scientists from the Moscow State University has been studying the behaviour of the recently-discovered iron oxide Fe4O5 . The group has succeeded in describing its complex structure, and proposed an explanation for its very unusual properties. The article appeared in the current issue of the journal Nature Chemistry.
The scientists discovered that when Fe4O5 iron oxide is cooled to temperatures below 150K, it goes through an unusual phase transition related to a formation of charge-density waves—which lead to a "four-dimensional" crystal structure. Artem Abakumov, one of the paper's authors, said that the study of this material would contribute to the understanding of the interconnection between magnetic and crystal structures.
The origins of this research date back to 1939, when the German physicist E.J.W. Verwey first discovered that the iron oxide Fe3O4—commonly known as the mineral magnetite—had a strange phase transition. Magnetite in its normal state is a relatively good electrical conductor, but when cooled below 120K its conductivity markedly decreased, and the material practically became an insulator. Scientists discovered that below 120K, the iron atoms arrange themselves into a kind of ordered structure. In this structure, the electrons cannot move freely within the material and act as charge carriers, and the oxide even becomes a ferroelectric. But the scientists could not explain what exactly changes in the structure, which physicists have spent the last century studying. Researchers guessed that the phenomenon was related to the presence of iron atoms in two different oxidation states (valences)—two and three—and their consequent ability to form ordered structures.
[...] "We have found that here, just as in magnetite, when cooling to lower than 150K occurs, an unusual structure evolves. It's something of a mixture between standard charge density waves forming dimers," Artem Abakumov said. "And the situation with the trimerons that was observed in magnetite. This was very complicated in the case of Fe4O5—what's known as a 'incommensurately modulated structure', in which we can't identify three-dimensional periodicity. However, the periodicity can be observed in a higher-dimensional space—in this specific case, in the four-dimensional space. When we mention the four-dimensionality of such structures, we are not actually talking about the existence of these oxides in four dimensions, of course. This is just a technical construct for the mathematical description of such highly complex ordering."
Charge-ordering transition in iron oxide Fe4O5 involving competing dimer and trimer formation (DOI: 10.1038/NCHEM.2478)
(Score: 4, Insightful) by devlux on Sunday April 17 2016, @12:45AM
A dimension, is just a way of measuring things in a quantifiable manner.
Time is a thing that can be measured in a quantifiable and meaningful way, ergo time is a dimension.
There are 4 consistent dimensions to the universe in which we exist, length, width, height and time.
Any point in the universe that ever was or ever will be can be described as a vector t,x,y,z
Furthermore time is inextricably linked to the spatial dimensions, but it is not as far as we can tell a "space like" dimension.
Yet the more mass/energy you put into a smaller sphere described by x,y,z the more x,y,z begin to warp and bend and this effect is observed as gravity which has known effects on time. So yes time is a dimension, just not a "space like" dimension and space is not a "time like" dimension. The point of interface between them appears to manifest as gravity.
Unrelated, but it opens with a good joke.
http://www.pbs.org/wgbh/nova/blogs/physics/2014/04/how-many-dimensions-does-the-universe-really-have/ [pbs.org]
Wish I could find the article now, but I remember reading a paper about a year or two back that was able to describe the accelerating expansion of the universe as an evolution of time into a space like dimension. Basically, time is hotspace just as energy is hot mass. It seemed well constructed and what I read was a pre-print before peer review, but I'm not able to find it on arxiv. If someone remembers it or can find it again, I'd be much obliged.
(Score: 2) by maxwell demon on Sunday April 17 2016, @11:38AM
Your explanation is actually of the worst type: Close enough to the truth that it cannot simply be done away as wrong, but still deviating enough from truth that it cannot be left alone.
You start with a possible definition of "dimension", which is not wrong but is not exactly the reason why we speak of time as the fourth dimension. According to that definition, you could also say temperature is a dimension (it's also a quantity we can measure in a quantifiable and meaningful way), and in a sufficiently abstract sense it's true. But time is the fourth dimension in a much more geometric sense.
This connection is related to relativity; however it already comes from special relativity, where there is no gravitation and no curvature of spacetime. The reason why time has to be considered to be unified with space in a four-dimensional spacetime that cannot be separated into space and time in an observer-independent way is the relativity of simultaneity, and the most direct manifestation of it is the constancy of the speed of light.
Also, gravitation doesn't just bend space, it bends spacetime. Gravitation cannot be described purely by the curvature of space (I think Gauss tried this for quite some time without success).
You are, however, correct that "spacelike" and "timelike" dimensions (or rather, directions in spacetime) are not completely equivalent. However that non-equivalence is smaller than you might think; basically it's a single sign that distinguishes space and time (and actually it's not even the sign itself that's relevant, but only the fact that it is different for spacelike and timelike directions).
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by devlux on Sunday April 17 2016, @11:06PM
The explanation is not wrong. Time, temperature, color etc are dimensions and can be quantized.
If it's quantifiable and measurable it can be a dimension mathematically.
You mention that time is basically a dimension with a sign to it.
It's still a dimension, but time is not the 4th dimension referenced by this article. ;)
(Score: 0) by Anonymous Coward on Monday April 18 2016, @05:44PM
guys guys it's all 1-dimensional strings vibrating [xkcd.com]