Can Symmetry be Dangerous?

Before, one of our friends' blogs wrote about the dangers of Agent Orange. Basically, the toxic molecule in question is named "2,3,7,8-tetrachloro-dibenzo-p-dioxin," or 2,3,7,8 TCDD" for short. It is formed as a by-product from the production of herbicides and pesticides, and was used excessively during the Vietnam War. It was especially emphasized in their blog that, "It is actually the most potent synthetic carcinogen ever tested in a laboratory."

But what does Agent Orange have to do with symmetric molecules?

(A 2,3,7,8-TCDD molecule diagram)

Well, you can see from the molecular structure shown above that, in fact, this molecule is almost perfectly symmetric! (For those of you who are group-theory-nuts out there, this molecule possesses D2h symmetry! More to come on that later on in the blog.)

Other characteristics of its symmetry include the following:

• All atoms in the molecule have completely full octets-- in other words, there are no electrons missing from their valence shells.
• There are no net dipole moments, which can be easily seen from the symmetric nature of the molecule.
• No formal charge differences exist among the atoms.
• No angles between atoms are "strained": all bonds are in their ideal angles.

So we can see just how beautifully symmetric this molecule really is.

But what does its symmetry have to do with its side-effects? 

If you think that the molecule's symmetry is just a coincidence, and that the dangerous side-effects of this molecule stem from other properties, you are not fully correct; its symmetry does affect its level of danger! 
Because of the symmetry discussed above, the molecule is VERY stable, which only adds to the damage. This stability gives 2,3,7,8-TCDD a half-life of 7-12 years, which means that the toxin will last for a very long time. So not only are the side-effects of TCDD-exposure devastating, but the risks of being exposed long after its introduction are also very high.

Also, because this dioxin shares structural similarities between it and aromatic hydrocarbons (or molecules made up of carbons and hydrogens and containing at least one benzene ring), the TCDD molecule can fight for the receptor site of aromatic hydrocarbon proteins. This allows the toxin to be absorbed into the body more easily. 

(Examples of aromatic hydrocarbons: Each big circle and hexagon in the diagram represents a benzene ring, which is an actual "ring" composed of 6 carbon atoms and 6 hydrogen atoms.)

So overall Agent Orange shows that despite their beautiful appearance and stability, symmetric molecules can be just as dangerous as any other molecules-- and in this case, even more dangerous.

Lastly, we now have to ask ourselves-- is it really worth pursuing the formation of new chemical products or other symmetric molecules? After all, although 2,3,7,8-TCDD was a by-product, it was still human-made-- we essentially brought this upon ourselves! So is it worth playing around with such molecules, with the giant health risks on our backs? We leave this question open to the reader.

Symmetry with that Glass of Emulsion: Yummy

Now, we have seen the symmetry of the aforementioned quasicrystals and we see the beauty. But we need to understand symmetry and its impact at home, at the breakfast table. You sit down (not that hungry, people are not usually very hungry when they wake up in the morning) at the breakfast table to do just that, to break your fast. You sit down to have a nice glass of emulsion with a pancake that has some of that sweet solid emulsion sitting right on top. Sounds pretty friggen disgusting? Strange how this is so intricately involved with the stark beauty of symmetry.

These are colloidal properties. Colloids are not quite heterogeneous and not quite homogenous. In terms of size, colloids meets the two types of mixtures in the middle at 1.0 x 10^-6. "Suspension of colloidal particles have been widely employed as model systems to study" phase changes. Now when measuring and studying this, spherical pictures of atoms and molecules are always used. Other shapes likes rods have been used as models but for very specific research purposes. It is well known that spheres do not account for the vast array of molecule shape and size. What people need to do is synthesize some of these micro particles. This has been done to some degree. Great minds at Yale University, Jin-Gyu Park,Jason D. Forster, and Eric R. Dufresne, have synthesized colloidal water. These are polymer particles with the same imitated symmetry as water molecules for the purposes of the study and research of condensed matter. 

Figure 1

Figure 2

Multistep polymerization is used. Take a quick peep above this text (Figure 1) and you will get the picture. The spherical micrometer sized colloids are swelled with a monomer solution. It is heated and this drives separation of the monomers (the solvent). Seeded polymerization is what is used. The results were seen under a scanning electron microscope (Figure 2). This is a genuine synthesis of chemical symmetry, all utilizing the lexicon of solutions. A symmetrical molecule, water, has been created using colloidal micro-molecules. This can be expanded beyond the domain of simple molecules like water, for sure. These colloidal properties, using seeded polymerization as the medium, can yield results, results that show that symmetry can be created, artificially, in the solutions market place.  

Are the Foundations of Science as Secure as We Think?

A few posts earlier we had mentioned how Dan Shechtman and his team had once been ridiculed for their theories and discoveries of quasicrystals. For years since the team's first discovery, they were even pressured by other scientists to give up and move to another field. Yet now we know that quasicrystals were actually only early for the time, and that now they are crucial substances that hold many practical and academic applications, especially in the world of crystallography. They have even been shown to exist naturally!

This, however, brings up a troubling question: if such an "established" theory as the Crystallographic Restriction Theorem, which, by the way, was proven not just scientifically but also mathematically, how do we know that other "established" theories that we "know" of are also flawed? How do we know that this is the only case in which our scientific community was incorrect?

The truth is, we don't know. We must remember that science cannot prove anything, since it merely uses observational data. Compelled by the logic of induction, science can at best strongly predict what happens. If we look a bit to the past, for example, we remember how at one point people believed in the geocentric-- rather than the heliocentric-- model. At the time, the former model of the universe was labeled correct, and other projections of the universe were quickly shot down.

But now we see that isn't the case, and that those who opposed the scientific community of the time were right all along-- scientists like Galileo and Copernicus.

So what does this all imply? That we must be cautious of the things we hold for granted. Hypotheses, theories, and even laws that we hold onto dearly today might just be history tomorrow, as was the case in the field of crystallography.

That's probably why such landmark discoveries are labeled as "revolutionary."

Quasicrystals "In Space!"

          As you may or may not know quasicrystals were discovered by scientists only in the last 40 or so years. And before that most scientists refused to believe that they even existed because of how crazy the concept of quasicrystals were. So imagine the surprise when two people by the name of Paul J Steinhardt and Luca Bindi discovered a meteorite containing quasicrystals in eastern Russia within the Koryak Mountains around the 1980s. Before this discovery, only one natrual quasicrystal had been documented. The sample in question, currently located in the Museum of Natural Florence, Italy, was found to have the symmetry of a soccerball; with six axes of five-fold symmetry forbidden to ordinary crystals. And what makes this all more interested was the type of meteorite that the quasicrystals were discovered in. This meteorite was a CV3 carbonaceous chondrite. And for the 3 of you people that don't understand meteor terminology, it means that this rock was formed around 4.5 billion years ago; around the time that the solar system first began. 

Meteor striking Earth's atmosphere. Scientists reveal that new, naturally occurring quasicrystal samples have been found in an environment that does not have the extreme terrestrial conditions needed to produce them, therefore strengthening the case that they were brought to Earth by a meteorite. (Credit: © JRB / Fotolia)

        This is a huge discovery. It means that something that's existence has been acknowledged within the last 40 years or so has been in production by the universe since the beginning of the universe or at least our own solar system. This creates several questions that have to be solved, and according to Paul J. Steinhardt, those questions are: "What does nature know that we don't?", How did the quasicrystal form so perfectly inside a complex meteorite when we normally have to work hard in the laboratory to get anything as perfect?", What other new phases can we find in this meteorite and what can they tell us about the early solar system?". While these questions are very good, I feel the need to add one more, call it some food for thought. What other things are there that modern science has already dismissed that are in fact legitimate? Thanks for reading.

Symmetry on a Larger Scale

We previously discussed how vital symmetry is on a small scale, but is symmetry important on a large scale? Just to refresh everyone's memory, symmetry is significant as it contributes to the boiling point of a compound, can assist in determining the compounds structure, or can effect the bond strength (a symmetrical "hydrogen bond" is stronger than a regular "hydrogen bond"). Quasicrystalls, incredibly symmetrical crystals, are versatile and can be used in various situations, but they are only about 150 micrometers in size! So does symmetry only effect small particles or molecules? Well, this depends because last year, the discovery channel claimed that the Milky Way galaxy is symmetric. Yes, we have just claimed that a 150 micrometer crystal is symmetric and the a 100,000-120,000 light year galaxy is symmetric. Just to put that into perspective: 1 light year is equal to 9.46*10^21 micrometers.

Milky Way galaxy

Quasicrystal under a scanning electron microscope

If symmetry applied to smaller molecules is applied to the Milky Way, many questions rise. As stated before, when molecules are symmetric and stacked on top of each other, they are incredibly difficult to separate. Since galaxies move, what if another galaxy, symmetric like the Milky Way, stacks atop the Milky Way. There are though to be at least 500 billion galaxies in the universe, so there has to be at least 1 that is symmetric like the Milky Way. Will there be attractive forces so strong that these galaxies will turn into one galaxy? As previously stated, scientists are able to determine a compound structure, so will the symmetry of our universe allow us to discover our universe's "structure"? Will knowing that our universe is symmetric cut out half of the work for astronomers?

Image depicting galaxies moving moving close to each other

Now, how can the Milky Way galaxy be symmetric? Simply put, half of the Milky Way galaxy is virtually the exact mirror image of the other half. This is incredibly similar to many molecules who's right side is just a mirror image of its left side. So if our galaxy is symmetric, does this mean that another planet exactly the same as earth must be on the opposite side of the galaxy? How many other galaxies are symmetric and what will be the deleterious effects of symmetry? Is our universe symmetric? Only time will tell.

Usage of Quasicrystals in Tools

           Quasicrystals have many different characteristics that allow them to used in many different scenarios. The first quasicrystals were metastable, meaning that if the crystals were exposed to heat or reheated at some point in time, it might vanish. This heavily limited there use  But within a few years stable quasicrystals were found in several different materials systems, including aluminum–copper–iron and aluminum–palladium–manganese.
                                    
Quasicrystals are extremely poor electrical and thermal conductors. In fact the thermal conductivity of quasicrystals containing more than 70 atomic percent aluminum is two orders ofmagnitude below that of aluminum and roughly equivalent to that of zirconia, which is used as a refractory material. Quasicrystals are
also exceptionally hard, and their surfaces have very low coefficients of friction, good wear resistance, and good oxidation and corrosion resistance. Also, depending on how they are prepared, quasicrystals can have coefficients of friction so low they are comparable to the coefficient of a diamond gliding over a diamond film.At first, there was an apparent obstacle to exploiting these properties: Bulk quasicrystalline materials are brittle at temperatures below a few hundred degrees Celsius. The solution to this problem was that quasicrystals made into coatings by the standard techniques of metallurgy, such as atomization and plasma spraying, retain the desirable properties, but not the brittleness, of the bulk material. So with these features, what can quasicrystals be used for? The first use lies in medicine, specifically medical tools. Put simply, there quasicrystals easily made into very strong and durable tools. Continuing on, titanium-based quasicrystals  particularly titanium–zirconium–nickel, would be very useful for hydrogen storage. The reason being that hydrogen likes to sit in tetrahedral sites in transition metals. Quasicrystals because of their shape have huge amounts of tetrahedral sites. In addition, hydrogen is very specific about its bonding partners. It doesn’t work well with aluminum, but it works beautifully with titanium, zirconium, and the rare earths. So the titanium quasicrystals have the combination of a favorable chemistry and a favorable structural unit. Ken Kelton of Washington University in St. Louis found that titanium–zirconium–nickel quasicrystals can absorb nearly two hydrogen atoms per metal atom which is more hydrogen than is absorbed by related crystalline and amorphous materials. Moreover, it is more hydrogen than is absorbed by the hydrogen-storage materials currently in use, such as the lanthanum–nickel compounds in renewable batteries in laptop computers. “We can store almost double the weight percent of hydrogen that can be stored in lanthanum–nickel-5,” Kelton said. Some problems with is though is that Titanium–zirconium–nickel tends to form a surface oxide that can delay hydrogen loading. “This is not uncommon,” Kelton commented, “and we can get around it by gently milling the quasicrystal ribbons or by electrolytic loading.” He also noted that titanium-zirconium–nickel has so far been produced only by melt-spinning. Although the quasicrystal is stable, the reactivity of titanium has prevented it from being produced by the more versatile techniques used to make aluminum-based quasicrystals. The final potential use would be in the field of solar power. While quasicrystals lack exotic optical properties, their resistance to corrosion and abrasion might yield solar panels that do not require the "round the clock" maintenance needed by regular solar panels. The ideal solar-absorber material shows large absorption in the solar spectrum and is highly reflective at longer wavelengths. These characteristics basically give the effect of a window in a closed car. Sunlight comes in and is absorbed by the seats, but  energy re-emitted as infrared radiation is trapped in the car by the windows. Thus, the car’s interior, becomes much hotter than its exterior. By similar means, solar-selective absorbers can reach temperatures as high as 500°C. Using quasicrystals, the closed-car effect can be achieved using a thin-film stack made up of a layer of quasicrystalline aluminum–copper–iron between two layers of the dielectric alumina deposited on a reflective metal had a solar absorptance of 90%.
          While all these uses of the quasicrystal remain mostly untested, many different companies and people are cautiously optimistic of this technology. And for good reason, as these crystals have the to potential to change many things in the world of humans.

Quasicrystals-- A Revolution in Crystallography

For centuries, the field of crystallography-- the science of how atoms and solids are arranged-- has followed a fundamental mathematical theorem called the Crystallographic Restriction Theorem (CRT). It states that periodic crystals, which are ordered on a microscopic level, can only contain 2-fold, 3-fold, 4-fold and 6-fold rotational symmetries.

(A regular snowflake is shown to have 6-fold rotational symmetry.)

This makes sense when you use pictures: for instance, try to cover an entire area with pentagons attached to each other, and you will indeed fail:

However, this theorem-- as well as the basis of crystallography itself-- has been corrected in 1984 with the revolutionary works of Dan Shechtman and his synthesis of aluminum-manganese alloys with icosahedral symmetry.

(A icosahedron has twenty equilateral triangles as its faces.)

This figure is especially troubling to believers of the original CRT, as it has numerous 5-fold symmetric axes. One such axis is shown below:

These crystals, due to their unusual symmetries, have been called quasiperiodical crystals, or in short quasicrystals. Because of their unusual characteristics--especially that of rotational symmetry-- its existence has been doubted by many scientists.

So how can such molecules be made, with the proven CRT still standing? Well, if we look at the second picture of this blog (the one with pentagons), we see that the gaps between the pentagons become the problem; however, in quasicrystals the gaps are filled with differently shaped atoms, while rotational symmetry is still maintained.

As Marjorie Senechal, a specialist in mathematical crystallography, describes it, such symmetries are forbidden. And such criticisms are what Mr. Shechtman and his team faced initially, when they published their highly-controversial results.

(image of Al6Mn)

Even after such criticisms were resolved, numerous scientists refused to believe in the entire concept; they continued to argue that these crystals, nonetheless, could only be formed synthetically (i.e. it cannot be naturally found). This belief was again proven false with the discovery of icosahedrite (Al63Cu24Fe13), the first natural quasicrystal found. This solid also has an icosahedral symmetry.

With the naked eye, it does not appear to be so special:

Yet on a microscopic level, this quasicrystal exhibits 5-fold symmetries-- a fact which surprises scientists even to this day. Its diffraction patterns, or patterns created when beams of X-rays strike a solid and spread into directions provided by the solid's edges, are shown below:

(Pattern (a) shows a 5-fold rotational symmetry, while (b) shows a 3-fold symmetry.)

Thus, since its appearance in the field of crystallography three decades ago, these quasicrystals have been studied vigorously by scientists around the globe. Hundreds of other quasicrystals, with 5-fold, 8-fold, 10-fold, 12-fold and 15-fold symmetries, have also been created.

(One such example is the aluminum-palladium-manganese quasicrystal; its atomic model is shown here. It exhibits 5-fold rotational symmetries but no translational symmetry.)

Paul Steinhardt, professor of physics at Princeton University, summarizes the effect of the emergence of quasicrystals as following:

The 30-year history of quasicrystals is one in which, time after time, the conventional scientific view about what is possible has been proven wrong.

This new subject is undoubtedly revolutionizing the field of crystallography. Thomas Kuhn, a prominent physicist and philosopher of science, would have gladly called it the bringer of a paradigm shift.

Nature: Awed and Humbled

In the words of President Obama these past few days "We are awed and humbled by nature's destructive power," in light of Hurricane Sandy. As a resident on the northeast, let me first offer my sympathies and say I stand in solidarity with all the people involved.

This brought me to this thought process. Forces in nature can cause up to 50 billion dollars in damages and can create beautifully formed, virtually symmetrical compounds. We must respect nature; that is a given. But can we respect it by imitating it, by synthesizing it in the lab? That is a good question, a question I shall attempt to answer now, with all of you, my friends.

If we can, should we? Just because we can doesn't necessarily mean we should. Kudos to Michael Crichton, whose books centered on these issues. Is it moral to create something found in nature? I must say no, I will not make any effort to disguise my opinions. I think that given our abilities, we should use them to the fullest extent and to our benefit, provided that they do not conflict with basic human rights. We are going to talk about the ethics and morals involved and I do not think we can do that without invoking God. Growing up Catholic, I was taught that we are all made in the image and likeness of God and that only God can create a human being. That is why the Roman Catholic Church does not condone cloning. But this same principle can be applied here. If only nature can create a super symmetrical compounds, is it moral for humans to do it?

This is my take. People were put here to do with their resources as they wish. I respect the Church's position on this issue. And perhaps cloning is one extreme; it is a replication, creation (however you would like to term it) of another life form and we can all agree that a compound, quasi-crystal, or anything like that is nothing like an actual animal. But the broader picture is the same. Do people have the right to replicate nature to their benefit? I say if God put us here, he did it so that we can do those very things. 

You know, for all you trekkies out there, and I'm not talking to you hooligans who just jumped on board since the J.J. Abrams movie came out (it was a fantastic movie, don't get me wrong), I hope you remember the scene in Kirk's room in Star Trek II: The Wrath of Khan where Spock, Dr, McCoy, and Kirk are discussing the Genesis project. The Genesis project was a plan to take a lifeless, dead planet and rejuvenate it with life to deal with the problems of over population and food supply. McCoy says "According to myth, the Earth was created in six days, now watch out, here comes Genesis. We'll do it for you in six minutes." Spock quips by saying he was not trying to analyze its moral implications. Eventually, the two scuffled as they usually do, with Spock admonishing Dr. McCoy. He says to him, "You must learn to govern your passions, they will be your undoing. Logic suggests..." wherein Dr. McCoy interjects to talk about the faulty of logic in this situation. Why did I just outline all this? Because I love Star Trek (hell of a thing when Spock died). But also because the same principle and same arguments are presented here. Logic suggests that we follow the path of scientific innovation, without the single glance at the ethical constraints. Dr. McCoy is the voice of a feeling human (not a stoical Vulcan) who has greater respect for such devices. Do we have enough respect for creation as to allow us to create super symmetrical compounds and great technologies for the fulfillment of our intentions (yes, initially good ones). I have to agree with Spock on this one. Those passions are the things that we can feel (and even be proud of) but we should not allow them to get in the way. One of my core beliefs is that I shall not impose my religious or moral beliefs on other people. For example, I believe abortion is morally wrong yet I am adamantly pro-choice. Again, the same principle applies here. I think it is human to go forward with these innovative feelings. "Out of all the souls I have encountered in my travels, his was the most....human." That line out of Spock's eulogy only makes sense to me from this perspective and interpretation.  

There are other schools of thought from which to see this argument and moral dilemma from. Does life hold inherent meaning? Do things have innate meaning or do they only have it when we grant this meaning onto them? Do things have ethical values at all? All depends on the mindset. If you are a fan of Seinfeld, then you are familiar with the absurdist, nihilistic view of life it takes. If you are a religious person, you find deep meaning in your faith.

This applies to super-symmetrical compounds in ways one could not have fathomed. Do we have the right to voraciously create without relishing and appreciating what has allowed us to do that? I implore you to think about these questions. Ponder them. You will come to many conflicting answers. Is this discovery or creation? I define discovery as something that has implications that are conducive to revolutions in science (like the discovery of gravity which is not recognized as a "discovery" by many). When we create these compounds, are we discovering them? Or is that terminology reserved for nature? 

These are the questions that haunt me...and I hope they haunt you too, Constant Reader.