Researchers attempt to uncover the origins of water's unusual properties

January 12, 2016 by Lisa Zyga, feature

The proposed pressure-temperature (P-T) phase diagram shows that, below a critical point, water is either in the high-density structure or in the low-density structure. However, above the critical point in a funnel-like region, water is constantly fluctuating between these two structures, and these structural fluctuations are what give rise to many of water’s anomalous properties. Credit: Nilsson and Pettersson. Nature Communications.
(—In many ways, water behaves very differently than other liquids do, and with important consequences: It's widely thought that water's unusual properties were essential for the development of life on Earth. One prime example is the fact that ice floats. Unlike other substances, frozen water is less dense than liquid water, and this anomaly allows fish and other aquatic lifeforms to survive in the water under a frozen layer of protective ice during cold periods. Water also has a high heat capacity, meaning it can absorb and release a large amount of heat while undergoing very little change in temperature. This property helps many living organisms maintain a relatively stable body temperature, and it also provides a pleasant climate in Europe due to the warm Gulf Stream current.

It's widely known that water's anomalous properties are related to its hydrogen bonds, which cause to arrange itself in a highly ordered way because of the attraction between the hydrogen atoms in one water molecule and the oxygen atoms in adjacent molecules. However, researchers do not completely understand how water's unique hydrogen-bonded structure leads to its anomalous properties.

In a review paper published in Nature Communications, physicists Anders Nilsson and Lars G.M. Pettersson from Stockholm University have pulled together the results from dozens of papers published over the past several years that have investigated water's molecular structure, often with the help of cutting-edge experimental tools and simulations.

In their interpretation of the data, the researchers have proposed a picture of water in which its unique properties arise from its heterogeneous structure.

The researchers propose that, in the pressure (P) and temperature (T) region where water exhibits its anomalous behaviors (the funnel-like region in the P-T phase diagram above), water coexists in two different types of structures: a highly ordered, low-density structure with strong hydrogen bonds, and a somewhat smashed, high-density structure with distorted . The origins of water's anomalous properties arise because these two types of structures are constantly fluctuating between one another in this heterogeneous phase, resulting in many small spatially separated regions of different structures.

"It is the fluctuations between high-density liquid and low-density liquid that give rise to the anomalous properties," Nilsson told

Take water's large heat capacity, for instance. As Nilsson explained, heat capacity is related to entropy fluctuations, and entropy is in turn related to the number of possible ways the available energy can be distributed in the system. Fluctuations between the low- and high-density local structures increase the magnitude of the entropy fluctuations and, consequently, the .

Outside of the funnel-like region, water stops behaving anomalously and begins behaving more like other liquids. In these regions, water's structure is homogeneous, existing as only the low-density structure below the funnel-like region and only the high-density structure above the funnel-like region.

While the new paper combines many years of data into one cohesive picture, many questions still remain. One unanswered question, for instance, is why does water's anomalous region occur at the same temperatures and pressures that sustain life? It seems likely that water's anomalous region served to place constraints on the conditions required for life to exist. A better understanding of this overlap could have implications for understanding life on a fundamental level.

Many other questions also require further investigation. The researchers explain that their proposed interpretation is a very simple picture, and it does not tell the exact degree of heterogeneity in water in the anomalous region, nor does it describe the nature of the boundaries between the spatially separated fluctuating regions.

Another area of investigation that has challenged researchers is the so-called "no-man's land" region, which refers to the possibility of liquid water at temperatures below 232 K (-42 °C and -42 °F) but above 150 K (-123 °C, -189 °F). It's extremely challenging to cool liquid water to these cold temperatures quickly enough so that it can be probed, even for a moment, before it turns to solid ice. In 2014, scientists successfully cooled liquid water to 5 K below no-man's land and measured its structure using an X-ray laser—the Linac Coherent Light Source at the SLAC National Accelerator Laboratory. Experiments like these are needed to answer the question of whether water can exist in a liquid state in this region, which would help complete the P-T phase diagram.

In the future, the researchers plan to investigate how water's structural fluctuations contribute to other intriguing phenomena.

"We will focus on using X-ray lasers to probe the supercooled regime and search for the liquid-liquid transition and second critical point," Nilsson said. "We are also developing probe dynamics using the femtosecond time resolution of the X-ray lasers, allowing eventually to probe the dynamics of these structural fluctuations. There might be some intricate coupling of time and space on various length and time scales that are still unknown.

"We hope that others will also bring other techniques involving time resolved two-dimensional IR spectroscopy, NMR and neutron scattering to further investigate water along these lines. Also further refinement of theoretical approaches to both calculate experimental observables but also to simulate ."

Explore further: Evidence for solid-liquid critical points of water in carbon nanotubes

More information: Anders Nilsson and Lars G.M. Pettersson. "The structural origin of anomalous properties of liquid water." Nature Communications. DOI: 10.1038/ncomms9998

Related Stories

How supercooled water is prevented from turning into ice

May 21, 2015

Water behaves in mysterious ways. Especially below zero, where it is dubbed supercooled water, before it turns into ice. Physicists have recently observed the spontaneous first steps of the ice formation process, as tiny ...

Structural memory of water persists on picosecond timescale

September 18, 2015

A team of scientists from the Max Planck Institute for Polymer Research (MPI-P) in Mainz, Germany and FOM Institute AMOLF in the Netherlands have characterized the local structural dynamics of liquid water, i.e. how quickly ...

Recommended for you

Coffee-based colloids for direct solar absorption

March 22, 2019

Solar energy is one of the most promising resources to help reduce fossil fuel consumption and mitigate greenhouse gas emissions to power a sustainable future. Devices presently in use to convert solar energy into thermal ...

Physicists reveal why matter dominates universe

March 21, 2019

Physicists in the College of Arts and Sciences at Syracuse University have confirmed that matter and antimatter decay differently for elementary particles containing charmed quarks.

ATLAS experiment observes light scattering off light

March 20, 2019

Light-by-light scattering is a very rare phenomenon in which two photons interact, producing another pair of photons. This process was among the earliest predictions of quantum electrodynamics (QED), the quantum theory of ...

How heavy elements come about in the universe

March 19, 2019

Heavy elements are produced during stellar explosion or on the surfaces of neutron stars through the capture of hydrogen nuclei (protons). This occurs at extremely high temperatures, but at relatively low energies. An international ...


Adjust slider to filter visible comments by rank

Display comments: newest first

3.5 / 5 (8) Jan 12, 2016
Re: "It is the fluctuations between high-density liquid and low-density liquid that give rise to the anomalous properties"

Perhaps, but this is not the aspect which lends the properties that life requires. Dr. Gerald Pollack has already conclusively shown that water has a transistor-like functionality in that it can switch between the structured and non-structured states with very subtle shifts in input. And he has published a number of books by now on how life uses this feature of water to EFFICIENTLY perform all of the actions that living organisms need to perform.

Articles like this one appear to ignore his important work, and this is a pattern which extends beyond just biology and water. Since his work questions entrenched lines of investigation like the sodium-pump hypothesis, there is resistance to its consideration.

And this is why Dr. Pollack is seeking a $1 billion endowment ...
2.7 / 5 (7) Jan 12, 2016
Sigh. I nearly lost my appetite for commenting after an "EU" crank visited in his futile pattern matching non-science. :-/ Pollack is legit, but he isn't much of a two-state water player, see the paper above, and his life emergence paper looks trivial (on aggregation).

But I got excited when Walter Blackstock on another thread reminded me [ https://johncarlo...nt-75864 ] of Wiggins's metabolic theories [ http://dx.plos.or....0001406 ] based on a two-state water region as per above.

Re "why does water's anomalous region occur at the same temperatures and pressures that sustain life? It seems likely that water's anomalous region served to place constraints on the conditions required for life to exist." If Wiggins solves the remaining two non-spontaneous steps in an enzyme free pathway between Keller et al's Hadean pentoses & amino acids and the purine products, vent theory has its RNA world basis!

2.5 / 5 (8) Jan 12, 2016
Warning! I looked at Pollack's Venture Institute, and the page about projects they could support raises warning flags, it is filled with folk science.

E.g. "What factors cause individual priorities to succumb to group dynamics?" (None, as long as it is the selfish gene's priorities we discuss.) "Dragonflies, bumblebees and hummingbirds should not fly according to prevailing theory." Wrong, wrong and wrong. "Special and general relativity form cornerstones of modern physics; yet scientists in surprising numbers argue that they are wrong..." Wrong. " Many consider the Sun a nuclear furnace. Yet investigators have uncovered evidence incompatible with that view." Wrong.

... and so on. Pollack outside the university seems to be either an uninformed kook or a very cherry picking thinker! (Fully expected I am sorry to say, it is consistent with our EU crank here.) I wouldn't invest there.
2.6 / 5 (5) Jan 12, 2016
It seems we need to do a review already ...

"Science is not a direct means for reaching the truth. Science works with hypotheses rather than with truths. This fact, although recognized, is usually forgotten. It gives rise to the creation of certain key groups within science which think that their hypotheses are indubitably solid truths, and think that the hypotheses of other minority groups are just extravagant or crackpot ideas ...

all through history, and even now, there have been many instances of discussion about how to interpret aspects of nature, with various possible options without a clear answer, in which a group of scientists have opted to claim their position is the good or orthodox one while other positions are heresies."

Martín López Corredoira, The Twilight of the Scientific Age
1.5 / 5 (4) Jan 12, 2016
So now we're finally talking about brown's gas, or Rhodes's gas, which is NOT oxy-hydrogen. Totally different parameters.

Oxyhydrogen gas mixtures do not self implode at just over 21 psi, which is what Brown's gas will do.

Oxyhydrogen does not produce a ignition wavefront of over 3600 meters per second, but brown's gas does.

The wiki entry on brown's gas says it is a fringe science term for 'oxyhydrogen'.

With two small bits of data that you can verify via experimentation, and this article (and 10k other stories), you can see that Wikipedia is full of shit and is very much a controlled media system.

The proper creation of brown's gas requires specific electrolyser design and specific electrolysis methodology. Which this article indicates, in it's discussion of the 'weird zone' for hydrogen bonding in water.

This is why HHO is called 'expanded water' by the knowledgeable.

Read proper in depth data on brown's gas, and you will see.
not rated yet Jan 16, 2016
KBK are you using the word 'implode' correctly?
not rated yet Jan 18, 2016
The molecular spatial charge distribution, leading to an inherent ionic-like proclivity, could be the source of water's bonding and atmospheric charge characteristics.
not rated yet Jan 19, 2016
not rated yet Jan 24, 2016
KBK are you using the word 'implode' correctly?

Not quite, but it applies in the sense of volumetric (displacement) change at room temperature and sea level atmosphere pressure.

Additionally, since the leading edge of the change, or reaction zone, if you will, happens at a staggeringly fast ~3600m a second, the word implosion tends to apply from a human macro viewing point.
not rated yet Jan 25, 2016
There has been a big breakthrough, and it marries the notion of "two state" to "transistor-like" functionality. It involve the realization that hydrogen bonding itself is the mechanism of H2O polarity, but mathematical relationship is inverse -- H bonding actually neutralizes polarity (explaining low viscosity of water) and partial breaking of H bonds activates polarity (explaining structure anamalies).
For more on this do research on the following:
Hydrogen Bonding Neutralizes H2O Polarity James McGinn

not rated yet Jan 25, 2016
It seems we need to do a review already ...

"Science is not a direct means for reaching the truth. Science works with hypotheses rather than with truths. This fact, although recognized, is usually forgotten.

It's been completely abandoned. They have fallen in love with their model. Their assumptions are hidden in their model and they write paper after paper arguing over small details of a model that carries over 70 anomalies. water science is a pathological science
not rated yet Jan 25, 2016
"Sigh. I nearly lost my appetite for commenting after an "EU" crank visited in his futile pattern matching non-science."

Given there are over 70 unresolved anomalies of H2O (that is 70 regularly observed phenomena that are unpredicted by the current model) I think you/we should be less concerned with "cranks" and more concerned with the business-as-usual, complacency of the non-cranks. If my experience communicating with them is any measure, these non-cranks seem to not be able to realize that their model is a model and not reality itself.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.