It sounds incredible - little is actually known about water. Scientists have now discovered a new form of ice that may hold the key to understanding H20, the life-sustaining liquid on Earth. And maybe in space? It is about - powdered water.
Researchers in the UK, at UCL and Cambridge universities, have discovered a new type of ice that could change our scientific understanding of water. Professor Christoph Salzman (UCL), one of the authors of the study, says:
"Water is the basis of all living things. Our existence depends on water, we go to Space in search of it, but from a scientific point of view we know little about water".
Namely, water has many anomalies that have puzzled scientists for a long time. For example, water is densest at 4 degrees Celsius and becomes less dense as it freezes - which is why ice floats. Also, the more pressure you put on liquid water, the easier it is to compress it - which deviates from the principle that applies to most other substances.
What kind of new ice is that?
The newly discovered ice is amorphous, that is, its molecules are not properly arranged as in ordinary, crystalline ice.
Amorphous ice is rare on Earth and occurs only in the cold upper layers of the atmosphere - but that is why it is the main type of ice in space, because there is not enough heat energy to form the ice crystals we know.
Amorphous ice was first discovered in a low-density form in the 1930s when scientists condensed water vapor on a metal surface cooled to -110 degrees Celsius. Its high-density state was discovered in the 1980s when ordinary ice was compressed to nearly -200 degrees Celsius.
What scientists have now discovered is amorphous ice of medium density - which looks like a fine white powder - and which, unlike all other known forms, had the same density as liquid water and whose state resembled - water in solid form.
They named the new ice - medium-density amorphous ice, MDA (medium-density amorphous ice).
"We were shaking the ice like crazy"
For the study, published in the journal Science, the research team used a well-known process called ball milling - in a container cooled to -200 degrees Celsius, ordinary ice was vigorously shaken together with steel balls.
Lead author Dr. Alexander Rosu-Finsen says about it: "We shook the ice like crazy and destroyed its crystal structure. Instead of ending up with smaller pieces of ice, we realized that we got a whole new kind of thing, with some extraordinary properties."
Amorphous ice is the most common form of water in the Universe
Scientists assume that MDA could exist within the icy moons of the outer solar system, since tidal forces from gas giants such as Jupiter and Saturn can act on ordinary ice like grinding with steel balls in a laboratory.
In addition, the team found that - when MDA is heated and recrystallized, it releases an extraordinary amount of heat - meaning it can cause tectonic movements and "icequakes" in the kilometre-thick ice sheet on moons such as Jupiter's Ganymede.
Professor Angelos Michaelides, lead author from Cambridge, says: "Amorphous ice is generally said to be the most abundant form of water in the Universe. Now we have yet to investigate how much of that ice is MDA and how geophysically active it is."
An exact replica of liquid water in solid form?
The researchers say this newly discovered ice may be a true glassy state of water—that is, an exact replica of liquid water in solid form, in the same way that the glass in windows is a solid form of liquid silica. However, another scenario is that MDA is not glassy at all, but is in a highly reduced crystalline state.
Co-author of the study Professor Andrea Sela (UCL): "We have shown that it is possible to create what appears to be a move-stop type of water. This is an unexpected and quite incredible discovery".
Dr. Michael Davies, who worked on the study's computer simulations and models, says: "Our discovery raises many questions about the nature of liquid water, so understanding the precise atomic structure of MDA is very important."
Why is density so important?
"We know 20 crystalline forms of ice, but only two main types of amorphous ice, known as high-density and low-density amorphous ice, have been discovered before. There is a huge gap between them, and it was assumed that there is no different ice in between. Our study shows that MDA right inside this density gap," says Professor Salzman.
The gap in density between the known amorphous types of ice has led scientists to believe that at very low temperatures - water actually exists as two liquids and that theoretically, at a certain temperature, both of these liquids can coexist, with one type floating above the other - as in mixing oil and water.
This hypothesis (oil/water) was demonstrated in a computer simulation, but not confirmed by experiment. The researchers who discovered MDA say their new study may raise questions about the validity of the idea.
Salzmen on this: "Existing models of water need to be retested. They must be able to explain the existence of amorphous ice of intermediate density. This could be the starting point for the final explanation of liquid water".
Bonus video:
