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Why water is weird
By Gary Taubes
Red Herring
March 26
This article is from the March 20, 2001, issue of
Red Herring magazine.
Water -- heavier when chilled, lighter when frozen, absorbing enormous heat with but a slight rise in temperature, the foundation of life, the most common of liquids, and the strangest. If only we knew how it worked.
"We still don't quantitatively understand the physics of liquid water," says Richard Saykally, a world-renowned chemist at the University of California at Berkeley. As a result, our best computer models don't simulate reactions in water, like the folding of a protein or the docking of a hormone and its target cell -- each a Holy Grail of biotech. Solving the mysteries of water would do for chemicals and pharmaceuticals what the wind tunnel did for aerospace: substitute fast, cheap calculations for slow, costly experiments. "We're talking about billions of dollars saved here," Mr. Saykally says.
Experimentalists like Mr. Saykally study how water actually behaves, at temperatures ranging from just above absolute zero to a few hundred degrees above its boiling point. Theorists, meanwhile, attempt to hone their computer simulations to match more closely the experimental observations. As increasingly powerful computers bring the two approaches into somewhat better agreement, scientists are learning that water is even weirder than they had thought.
LIQUID MYSTERY
Take virtually any liquid -- molten iron, for instance -- and freeze part of it into a solid; the solid will sink to the bottom. But ice floats, and the question is why. Indeed, water reaches peak density at 4 degrees Celsius, or around 40 degrees Fahrenheit.
"In school," says H. Eugene Stanley, a physicist at Boston University, "we learn that if water is in equilibrium with ice, the temperature must be zero Celsius. That's not true. The water at the bottom is not zero, but four Celsius, and the reason is that below four Celsius, the water starts becoming lighter, so the heavier four-Celsius water sinks to the bottom of the glass and just stays there."
Mr. Stanley describes this as the most remarkable of the "magical properties" of water, although there are plenty of others. There are, for instance, 5 different kinds, or phases, of liquid water, not to be confused with the 12 to 14 different phases of ice. Ice forms a crystal lattice, and each phase has its own structure. As a crystal, ice is as different from water as diamonds are from pencil lead. You can, for example, supercool water so that rather than freezing at 0 degrees Celsius, as it prefers to do, it will stay a liquid down to roughly -38 degrees Celsius. Water typically won't freeze without some impurities around which its molecules can begin to coalesce. For this reason, researchers who study supercooled water do so with the purest water they can get.
At -38 degrees Celsius, however, even the purest water spontaneously turns to ice. When that happens, "it does so with an audible bang, like a little bomb," says Austen Angell, a University of Arizona chemist who holds the world record for supercooling water. From -38 to -120 degrees Celsius, it's ice all the way, a temperature regime that Mr. Stanley calls "no-man's land," by which he means "no liquid." But below -120 degrees Celsius, it's possible to make what's known as ultraviscous water, a liquid as thick as molasses. Below -135 degrees Celsius comes glassy water, a solid having no crystal structure.
Most of water's strange properties stem from the peculiar bonds formed between neighboring H2O molecules. The bonds are formed by the two hydrogen atoms, which stick out from the oxygen at an angle of exactly 106 degrees -- "Mickey Mouse ears," Mr. Stanley calls them, "with the two positive hydrogen atoms as the ears, and two little feet sticking out, which are the negatively charged pairs."
The bond angle doesn't allow water molecules to bind ears-to-feet. Instead, the left ear of one molecule goes to the foot of a second, and the right ear goes to the foot of a third. At any given moment, only a few water molecules are likely to be bound at both ears and both feet. Others will have only three bonds, and still others only two.
The result is hard to simulate because you can't treat every water molecule as identical. Nor can you portray them as spheres, with perfect symmetry that would cut back on the number of spatial relationships, considerably easing the calculating load. Moreover, the electromagnetic forces between Mickey's ears and feet have a relatively long range, so you have to take into account not merely neighboring molecules but those farther apart as well.
TESTING THE WATERS
As computing power has grown exponentially over the years and modeling techniques have improved, so have simulations, which can now do a reasonable job of modeling a few thousand water molecules at a time. The models explain the four-degree temperature anomaly and some other conundrums just as Mr. Stanley did in his suggestion 20 years ago -- at any one time, the water molecules are engaged in the largest possible number of "good" hydrogen bonds. In ice, for instance, the hydrogen bond network is fully engaged, with each Mickey Mouse molecule locked onto its neighbors by two ears and two feet and occupying its maximum volume.
In water, because one or more of the hydrogen bonds is always broken, the molecules can move a little closer than they can in ice, allowing them more ways to arrange themselves. Lower the temperature, and you get "a little bit of a solid phase inside the liquid phase, and, as you lower the temperature further, you get more and more of these little bits of ice forming," Mr. Stanley says, like "plums in the plum pudding."
But does this transition between phases happen in reality or just in the computer? The ultimate test of a model is whether it predicts a phenomenon that experimentalists have yet to discover. In the case of Mr. Stanley's water simulation, this happened in 1992, when he and two collaborating physicists, Peter Poole of the University of Western Ontario and Francesco Sciortino of the University of Roma La Sapienta, noticed a coalescing of the plums in the plum pudding at roughly -50 degrees Celsius. The water seemed to be separating into a less dense phase of highly bonded water and a denser phase of less well-bonded water -- a kind of liquid water never before seen.
The proposition was, and still is, controversial. Indirect evidence is mounting, but direct evidence is hard to come by. "Heat capacity, compressibility -- quite a lot of the properties of water measured in that region show this type of divergence," says Mr. Saykally. "That's the standard hallmark of a phase transition near a critical point in the neighborhood."
The only direct experimental evidence of the phenomenon comes from Osamu Mishima of Japan's National Institute for Research in Inorganic Materials. In 1994, Mr. Mishima demonstrated that glassy water has high- and low-density phases and a transition from the former to the latter that Mr. Stanley says "pops like popcorn" as the glassy water expands. More recently, Mr. Mishima and Mr. Stanley have plotted the melting temperature against the pressure of superpure water and discovered kinks in the resulting curves -- kinks that are consistent with transition to a new form of liquid water.
Meanwhile, Mr. Saykally wants to infer Niagara Falls from a drop of water by fully calculating the behavior first of two water molecules, then three, four, and onward. He hopes to end up with a water model that is demonstrably better than that of Mr. Stanley or, for that matter, anyone else. "It should be able to do everything," Mr. Saykally says, "to calculate any properties whatsoever of liquid water more accurately than they've ever been described before."
Gary Taubes is a freelance writer living in Venice, California. Write to
letters@redherring.com.
1997-2001 Red Herring Communications. All Rights Reserved.
Thanks for the memory
Experiments have backed what was once a scientific 'heresy', says Lionel Milgrom
Lionel Milgrom
Guardian
Thursday March 15, 2001
A bout homeopathy, Professor Madeleine Ennis of Queen's University Belfast is, like most scientists, deeply sceptical. That a medicinal compound diluted out of existence should still exert a therapeutic effect is an affront to conventional biochemistry and pharmacology, based as they are on direct and palpable molecular events. The same goes for a possible explanation of how homoeopathy works: that water somehow retains a "memory" of things once dissolved in it.
This last notion, famously promoted by French biologist Dr Jacques Benveniste, cost him his laboratories, his funding, and ultimately his international scientific credibility. However, it did not deter Professor Ennis who, being a scientist, was not afraid to try to prove Benveniste wrong. So, more than a decade after Benveniste's excommunication from the scientific mainstream, she jumped at the chance to join a large pan-European research team, hoping finally to lay the Benveniste "heresy" to rest. But she was in for a shock: for the team's latest results controversially now suggest that Benveniste might have been right all along.
Back in 1985, Benveniste began experimenting with human white blood cells involved in allergic reactions, called basophils. These possess tiny granules containing substances such as histamine, partly responsible for the allergic response. The granules can be stained with a special dye, but they can be decolourised (degranulated) by a substance called anti-immunoglobulin E or aIgE. That much is standard science. What Benveniste claimed so controversially was that he continued to observe basophil degranulation even when the aIgE had been diluted out of existence, but only as long as each dilution step, as with the preparation of homoeopathic remedies, was accompanied by strong agitation.
After many experiments, in 1988 Benveniste managed to get an account of his work published in Nature, speculating that the water used in the experiments must have retained a "memory" of the original dissolved aIgE. Homoeopaths rejoiced, convinced that here at last was the hard evidence they needed to make homoeopathy scientifically respectable. Celebration was short-lived. Spearheaded by a Nature team that famously included a magician (who could find no fault with Benveniste's methods - only his results), Benveniste was pilloried by the scientific establishment.
A British attempt (by scientists at London's University College, published in Nature in 1993) to reproduce Benveniste's findings failed. Benveniste has been striving ever since to get other independent laboratories to repeat his work, claiming that negative findings like those of the British team were the result of misunderstandings of his experimental protocols. Enter Professor Ennis and the pan-European research effort.
A consortium of four independent research laboratories in France, Italy, Belgium, and Holland, led by Professor M Roberfroid at Belgium's Catholic University of Louvain in Brussels, used a refinement of Benveniste's original experiment that examined another aspect of basophil activation. The team knew that activation of basophil degranulation by aIgE leads to powerful mediators being released, including large amounts of histamine, which sets up a negative feedback cycle that curbs its own release. So the experiment the pan-European team planned involved comparing inhibition of basophil aIgE-induced degranulation with "ghost" dilutions of histamine against control solutions of pure water.
In order to make sure no bias was introduced into the experiment by the scientists from the four laboratories involved, they were all "blinded" to the contents of their test solutions. In other words, they did not know whether the solutions they were adding to the basophil-aIgE reaction contained ghost amounts of histamine or just pure water. But that's not all. The ghost histamine solutions and the controls were prepared in three different laboratories that had nothing further to do with the trial.
The whole experiment was coordinated by an independent researcher who coded all the solutions and collated the data, but was not involved in any of the testing or analysis of the data from the experiment. Not much room, therefore, for fraud or wishful thinking. So the results when they came were a complete surprise.
Three of the four labs involved in the trial reported a statistically significant inhibition of the basophil degranulation reaction by the ghost histamine solutions compared with the controls. The fourth lab gave a result that was almost significant, so the total result over all four labs was positive for the ghost histamine solutions.
Still, Professor Ennis was not satisfied. "In this particular trial, we stained the basophils with a dye and then hand-counted those left coloured after the histamine- inhibition reaction. You could argue that human error might enter at this stage." So she used a previously developed counting protocol that could be entirely automated. This involved tagging activated basophils with a monoclonal antibody that could be observed via fluorescence and measured by machine.
The result, shortly to be published in Inflammation Research, was the same: histamine solutions, both at pharmacological concentrations and diluted out of existence, lead to statistically significant inhibition of basophile activation by aIgE, confirming previous work in this area.
"Despite my reservations against the science of homoeopathy," says Ennis, "the results compel me to suspend my disbelief and to start searching for a rational explanation for our findings." She is at pains to point out that the pan-European team have not reproduced Benveniste's findings nor attempted to do so.
Jacques Benveniste is unimpressed. "They've arrived at precisely where we started 12 years ago!" he says. Benveniste believes he already knows what constitutes the water-memory effect and claims to be able to record and transmit the "signals" of biochemical substances around the world via the internet. These, he claims, cause changes in biological tissues as if the substance was actually present.
The consequences for science if Benveniste and Ennis are right could be earth shattering, requiring a complete re-evaluation of how we understand the workings of chemistry, biochemistry, and pharmacology.
One thing however seems certain. Either Benveniste will now be brought in from the cold, or Professor Ennis and the rest of the scientists involved in the pan-European experiment could be joining him there.
By Gary Taubes
Red Herring
March 26
This article is from the March 20, 2001, issue of
Red Herring magazine.
Water -- heavier when chilled, lighter when frozen, absorbing enormous heat with but a slight rise in temperature, the foundation of life, the most common of liquids, and the strangest. If only we knew how it worked.
"We still don't quantitatively understand the physics of liquid water," says Richard Saykally, a world-renowned chemist at the University of California at Berkeley. As a result, our best computer models don't simulate reactions in water, like the folding of a protein or the docking of a hormone and its target cell -- each a Holy Grail of biotech. Solving the mysteries of water would do for chemicals and pharmaceuticals what the wind tunnel did for aerospace: substitute fast, cheap calculations for slow, costly experiments. "We're talking about billions of dollars saved here," Mr. Saykally says.
Experimentalists like Mr. Saykally study how water actually behaves, at temperatures ranging from just above absolute zero to a few hundred degrees above its boiling point. Theorists, meanwhile, attempt to hone their computer simulations to match more closely the experimental observations. As increasingly powerful computers bring the two approaches into somewhat better agreement, scientists are learning that water is even weirder than they had thought.
LIQUID MYSTERY
Take virtually any liquid -- molten iron, for instance -- and freeze part of it into a solid; the solid will sink to the bottom. But ice floats, and the question is why. Indeed, water reaches peak density at 4 degrees Celsius, or around 40 degrees Fahrenheit.
"In school," says H. Eugene Stanley, a physicist at Boston University, "we learn that if water is in equilibrium with ice, the temperature must be zero Celsius. That's not true. The water at the bottom is not zero, but four Celsius, and the reason is that below four Celsius, the water starts becoming lighter, so the heavier four-Celsius water sinks to the bottom of the glass and just stays there."
Mr. Stanley describes this as the most remarkable of the "magical properties" of water, although there are plenty of others. There are, for instance, 5 different kinds, or phases, of liquid water, not to be confused with the 12 to 14 different phases of ice. Ice forms a crystal lattice, and each phase has its own structure. As a crystal, ice is as different from water as diamonds are from pencil lead. You can, for example, supercool water so that rather than freezing at 0 degrees Celsius, as it prefers to do, it will stay a liquid down to roughly -38 degrees Celsius. Water typically won't freeze without some impurities around which its molecules can begin to coalesce. For this reason, researchers who study supercooled water do so with the purest water they can get.
At -38 degrees Celsius, however, even the purest water spontaneously turns to ice. When that happens, "it does so with an audible bang, like a little bomb," says Austen Angell, a University of Arizona chemist who holds the world record for supercooling water. From -38 to -120 degrees Celsius, it's ice all the way, a temperature regime that Mr. Stanley calls "no-man's land," by which he means "no liquid." But below -120 degrees Celsius, it's possible to make what's known as ultraviscous water, a liquid as thick as molasses. Below -135 degrees Celsius comes glassy water, a solid having no crystal structure.
Most of water's strange properties stem from the peculiar bonds formed between neighboring H2O molecules. The bonds are formed by the two hydrogen atoms, which stick out from the oxygen at an angle of exactly 106 degrees -- "Mickey Mouse ears," Mr. Stanley calls them, "with the two positive hydrogen atoms as the ears, and two little feet sticking out, which are the negatively charged pairs."
The bond angle doesn't allow water molecules to bind ears-to-feet. Instead, the left ear of one molecule goes to the foot of a second, and the right ear goes to the foot of a third. At any given moment, only a few water molecules are likely to be bound at both ears and both feet. Others will have only three bonds, and still others only two.
The result is hard to simulate because you can't treat every water molecule as identical. Nor can you portray them as spheres, with perfect symmetry that would cut back on the number of spatial relationships, considerably easing the calculating load. Moreover, the electromagnetic forces between Mickey's ears and feet have a relatively long range, so you have to take into account not merely neighboring molecules but those farther apart as well.
TESTING THE WATERS
As computing power has grown exponentially over the years and modeling techniques have improved, so have simulations, which can now do a reasonable job of modeling a few thousand water molecules at a time. The models explain the four-degree temperature anomaly and some other conundrums just as Mr. Stanley did in his suggestion 20 years ago -- at any one time, the water molecules are engaged in the largest possible number of "good" hydrogen bonds. In ice, for instance, the hydrogen bond network is fully engaged, with each Mickey Mouse molecule locked onto its neighbors by two ears and two feet and occupying its maximum volume.
In water, because one or more of the hydrogen bonds is always broken, the molecules can move a little closer than they can in ice, allowing them more ways to arrange themselves. Lower the temperature, and you get "a little bit of a solid phase inside the liquid phase, and, as you lower the temperature further, you get more and more of these little bits of ice forming," Mr. Stanley says, like "plums in the plum pudding."
But does this transition between phases happen in reality or just in the computer? The ultimate test of a model is whether it predicts a phenomenon that experimentalists have yet to discover. In the case of Mr. Stanley's water simulation, this happened in 1992, when he and two collaborating physicists, Peter Poole of the University of Western Ontario and Francesco Sciortino of the University of Roma La Sapienta, noticed a coalescing of the plums in the plum pudding at roughly -50 degrees Celsius. The water seemed to be separating into a less dense phase of highly bonded water and a denser phase of less well-bonded water -- a kind of liquid water never before seen.
The proposition was, and still is, controversial. Indirect evidence is mounting, but direct evidence is hard to come by. "Heat capacity, compressibility -- quite a lot of the properties of water measured in that region show this type of divergence," says Mr. Saykally. "That's the standard hallmark of a phase transition near a critical point in the neighborhood."
The only direct experimental evidence of the phenomenon comes from Osamu Mishima of Japan's National Institute for Research in Inorganic Materials. In 1994, Mr. Mishima demonstrated that glassy water has high- and low-density phases and a transition from the former to the latter that Mr. Stanley says "pops like popcorn" as the glassy water expands. More recently, Mr. Mishima and Mr. Stanley have plotted the melting temperature against the pressure of superpure water and discovered kinks in the resulting curves -- kinks that are consistent with transition to a new form of liquid water.
Meanwhile, Mr. Saykally wants to infer Niagara Falls from a drop of water by fully calculating the behavior first of two water molecules, then three, four, and onward. He hopes to end up with a water model that is demonstrably better than that of Mr. Stanley or, for that matter, anyone else. "It should be able to do everything," Mr. Saykally says, "to calculate any properties whatsoever of liquid water more accurately than they've ever been described before."
Gary Taubes is a freelance writer living in Venice, California. Write to
letters@redherring.com.
1997-2001 Red Herring Communications. All Rights Reserved.
Thanks for the memory
Experiments have backed what was once a scientific 'heresy', says Lionel Milgrom
Lionel Milgrom
Guardian
Thursday March 15, 2001
A bout homeopathy, Professor Madeleine Ennis of Queen's University Belfast is, like most scientists, deeply sceptical. That a medicinal compound diluted out of existence should still exert a therapeutic effect is an affront to conventional biochemistry and pharmacology, based as they are on direct and palpable molecular events. The same goes for a possible explanation of how homoeopathy works: that water somehow retains a "memory" of things once dissolved in it.
This last notion, famously promoted by French biologist Dr Jacques Benveniste, cost him his laboratories, his funding, and ultimately his international scientific credibility. However, it did not deter Professor Ennis who, being a scientist, was not afraid to try to prove Benveniste wrong. So, more than a decade after Benveniste's excommunication from the scientific mainstream, she jumped at the chance to join a large pan-European research team, hoping finally to lay the Benveniste "heresy" to rest. But she was in for a shock: for the team's latest results controversially now suggest that Benveniste might have been right all along.
Back in 1985, Benveniste began experimenting with human white blood cells involved in allergic reactions, called basophils. These possess tiny granules containing substances such as histamine, partly responsible for the allergic response. The granules can be stained with a special dye, but they can be decolourised (degranulated) by a substance called anti-immunoglobulin E or aIgE. That much is standard science. What Benveniste claimed so controversially was that he continued to observe basophil degranulation even when the aIgE had been diluted out of existence, but only as long as each dilution step, as with the preparation of homoeopathic remedies, was accompanied by strong agitation.
After many experiments, in 1988 Benveniste managed to get an account of his work published in Nature, speculating that the water used in the experiments must have retained a "memory" of the original dissolved aIgE. Homoeopaths rejoiced, convinced that here at last was the hard evidence they needed to make homoeopathy scientifically respectable. Celebration was short-lived. Spearheaded by a Nature team that famously included a magician (who could find no fault with Benveniste's methods - only his results), Benveniste was pilloried by the scientific establishment.
A British attempt (by scientists at London's University College, published in Nature in 1993) to reproduce Benveniste's findings failed. Benveniste has been striving ever since to get other independent laboratories to repeat his work, claiming that negative findings like those of the British team were the result of misunderstandings of his experimental protocols. Enter Professor Ennis and the pan-European research effort.
A consortium of four independent research laboratories in France, Italy, Belgium, and Holland, led by Professor M Roberfroid at Belgium's Catholic University of Louvain in Brussels, used a refinement of Benveniste's original experiment that examined another aspect of basophil activation. The team knew that activation of basophil degranulation by aIgE leads to powerful mediators being released, including large amounts of histamine, which sets up a negative feedback cycle that curbs its own release. So the experiment the pan-European team planned involved comparing inhibition of basophil aIgE-induced degranulation with "ghost" dilutions of histamine against control solutions of pure water.
In order to make sure no bias was introduced into the experiment by the scientists from the four laboratories involved, they were all "blinded" to the contents of their test solutions. In other words, they did not know whether the solutions they were adding to the basophil-aIgE reaction contained ghost amounts of histamine or just pure water. But that's not all. The ghost histamine solutions and the controls were prepared in three different laboratories that had nothing further to do with the trial.
The whole experiment was coordinated by an independent researcher who coded all the solutions and collated the data, but was not involved in any of the testing or analysis of the data from the experiment. Not much room, therefore, for fraud or wishful thinking. So the results when they came were a complete surprise.
Three of the four labs involved in the trial reported a statistically significant inhibition of the basophil degranulation reaction by the ghost histamine solutions compared with the controls. The fourth lab gave a result that was almost significant, so the total result over all four labs was positive for the ghost histamine solutions.
Still, Professor Ennis was not satisfied. "In this particular trial, we stained the basophils with a dye and then hand-counted those left coloured after the histamine- inhibition reaction. You could argue that human error might enter at this stage." So she used a previously developed counting protocol that could be entirely automated. This involved tagging activated basophils with a monoclonal antibody that could be observed via fluorescence and measured by machine.
The result, shortly to be published in Inflammation Research, was the same: histamine solutions, both at pharmacological concentrations and diluted out of existence, lead to statistically significant inhibition of basophile activation by aIgE, confirming previous work in this area.
"Despite my reservations against the science of homoeopathy," says Ennis, "the results compel me to suspend my disbelief and to start searching for a rational explanation for our findings." She is at pains to point out that the pan-European team have not reproduced Benveniste's findings nor attempted to do so.
Jacques Benveniste is unimpressed. "They've arrived at precisely where we started 12 years ago!" he says. Benveniste believes he already knows what constitutes the water-memory effect and claims to be able to record and transmit the "signals" of biochemical substances around the world via the internet. These, he claims, cause changes in biological tissues as if the substance was actually present.
The consequences for science if Benveniste and Ennis are right could be earth shattering, requiring a complete re-evaluation of how we understand the workings of chemistry, biochemistry, and pharmacology.
One thing however seems certain. Either Benveniste will now be brought in from the cold, or Professor Ennis and the rest of the scientists involved in the pan-European experiment could be joining him there.