Weekly Roundup 30

The scientific method is a very interesting thing. Despite the fact it is given the definite article there are in fact other scientific methods that are very rarely talked about. It may be an attempt at dishonesty, since all other methods are almost unanimously deemed inferior, why bother even mentioning them. Just pretend there’s only one and don’t confuse people. But I think learning about past inferiority is important for projecting future success and so learning at least the basics of these methods is necessary. Since this is closer to scientific philosophy referring to it as epistemology, the philosophical study of knowledge seems more appropriative. The meditative method of understanding involves simply internalising information and seeing what conclusion can be arrived at through logic. We see this idea creep in on maths and theoretical physics where experiments are rare and so long as the equation follows through it is considered valid knowledge gained. The anarchic method is almost the opposite  where information is gained simply be doing. If I do X to Y while Z is true this happens, and so long as all those things are true again then the thing will happen again. Astronomy has this most blatantly with observations. Knowledge can be gained about star and planet locations without and experiment being performed as what experiment is required to know of something position. The anarchic method, however,  lacks true predictive ability but is certain of what is happening now while the meditative method can give predictions but it is in question whether the mathematical  model even represents anything to begin with. It is important in science to keep focus but not to stick so dogmatically to a method that it leads mindless action.

Until the light shines, goodnight.

Investigating Heavy Ions

Although it is easy to think of electrons as existing in specific orbits and adding an electron either adds to the same orbit or creates a new orbit; this is a great simplification. Helium’s electron structure is not just hydrogen’s with another electron added on. The two electrons will repel each other for a start and the extra proton will pull the electron cloud closer overall. This is why all elements have unique spectral lines and not just the previous element’s with an extra line or two added. This means that the ions of elements also have unique spectral lines as well.

Now for very heavy elements with high numbers of protons it is hard to remove more than a couple of electrons and so the emission spectra of ionised elements like gold, tin and tungsten were unknown and have recently been found. By injecting pellets of the elements into a plasma and then observing in the ultraviolet spectrum the emissions of ions like  terbium, holmium, and thulium were found for the first time. Now about two thirds of the elements fifty to eighty three have been analysed. This is an amazing piece of progress as it opens the opportunities for elements like gadolinium and bismuth (two of the other elements analysed) to be used in plasma lighting. Many of the elements under scrutiny have various uses in plasma physics even some going towards the ultimate goal of nuclear fusion.  But that still seems quite a way away at this point, but steps like this make the road one step shorter.

Creating Photochemical Catalysts

A  photocatalyst, as the name suggests, speeds up a photochemical reaction, a reaction that operates in the presence of (normally) ultraviolet light. They do this by creating electron hole pairs according to band theory which then produce free radicals (molecules with an unbonded electron) which are very reactive and allow for a different chemical pathway with a lower energy requirement and so speed up the reaction. One of the most common photochemical reactions is water splitting to produce hydrogen and oxygen. Using electrolysis to split water is very energy inefficient and using a pure reaction is abhorrently slow so a catalyst is used very often.

Recently a new photocatalyst, C12N7H3, has been designed. Its crystal structure gives it a controllable surface area and the fact it is organic, containing no metal, is a big advantage. Metal catalysts skim the chance of heavy metal poisoning and the limited manipulation of the active sites is always a problem. The full electronic structure and alignment states of C12N7H3 has already been calculated and there are four different methods of suggested application for the catalyst already laid out. The use of hydrogen as a possible future fuel means that any improvement in its production, no matter how small, has the possibility of creating a massive difference in the future.

 

Curbing Titanium’s Creeping Nature

The physics of a thin wire appears at first to be very simple: apply the Hooke’s law so long as the wire hasn’t broken. But as with all branches of physics, adding more details makes the algebra treatment more accurate but quite a lot more complicated. Concepts like stress and strain, Young Modulus, hysteresis, elastic limit and limit of proportionality come in and make the mathematics more difficult if you want a answer that is closer to the truth. I will be writing a page on elastics quite soon but today the main focus is the idea of “creep”.So long as wire has a weight on it, it will continue to extend. This creeping is almost imperceivable at first but as a greater load is added the rate of creep increases until the point where the wire extends, keeps on extending and snaps.

Alloys of titanium are favoured in many construction projects because of titanium’s high melting point, resistance to corrosion and good strength to weight ratio. The main reason why alloys are used almost exclusively is because all metals are softer when pure and so creep much more easily. Silicon is a very common additive and used in close to all titanium alloys to massively reduce creeping but too much would make the alloy brittle and prone to fracture. A study has recently looked into exactly what happens in the mixture to ensure this effect occurs. By performing calculations based on the geometry and the interaction energy between the silicon and metal atoms it was concluded a strong covalent could form in the metal lattice disrupting the sliding structure meaning the planes could no longer slide over each other with ease. Combined with the different bonding between a metal and a metalloid the result is a much harder substance with less creep but also easier to crack.

Insuring Electron-Positron Equivalency

For a long time Issac Newton’s theory of universal gravitation was the accepted truth of the way gravity works. But it was revealed by Einstein that it was just an estimation. A very good estimation, Newton’s equations were accurate enough to get humanity to the moon, but they were still not perfect. It is Einstein’s field equations and the theory of general relativity that is now what is believed to be true. Many of the core concepts have however remained the same. The most key one being the equivalence principles. If two objects are dropped in a uniform gravitational field they will experience the same acceleration, this is true no matter what the objects are. There is nothing inherent in an object that can make it experience gravity more or less and we have never found anything that breaks this rule.

But being thorough is essential in science. Since we know that all matter ever observed obeys this rule it must also be proven that antimatter does also. To do this data from the Large Electron Positron (LEP) collider was analysed. The actual experiment being performed was determining the mass of the W boson but during this the production of positrons in the synchotron was inevitable and data for theses was also recorded. The analysis came up with a 0.13% maximum on possible deviation of equivalency, a massive improvement on the previous 4%. This means there is very little chance that the positron is effected by gravity differently as this reduced percentage falls in the error range of the experiment. Although it seems obvious that this would be the case, making such assumptions has led to massive oversights in the past. This is why the scientific method has to applied almost compulsively to all situations with no exception.

Demonstrating Phonon Decay

Tungsten (IV) telluride (WTe2) is a very unique material with some amazing properties. I have talked before about magnetoresistance, the change in resistance of a material due to an applied magnetic field. The unique thing is that WTe2 changes its resistance by about 13 million percent and it can’t be saturated (when extra magnetic field fails change magnetisation of the material). It is also the first and only real material that constantly compensates keeping the same amount of electrons in the conduction and valence band at all times.

Recently a paper has been published looking into the vibrations in the lattice of WTe2 and the exact mechanisms behind phonons that appear there. The most interesting thing that was looked into was the transformation of optical phonons into acoustic phonons. Acoustic phonons are very similar to sound waves, thus the name, and are the atoms in the crystal vibrating from their mean position sending the wave energy thorough a system. Optical phonons are where there are two different atoms in the crystal (tungsten and tellurium in this case) that get polarised differently by light and so repel. Each pair of atoms will push out of position to get further away from their partner and it appears once the light is removed the energy that was in these optical phonons is turned into acoustic phonons. Understanding just one property of such a material could get scientists thinking about applications and eventually it could be an essential component in electronic circuits of the future.

Estimating Future Electrical Demand

In Britain the National Grid is responsible for distributing electricity around the country. It is, in essence, a series of generators, pylons and transformers that need to keep up with the demand of the population. This is especially a problem whenever the World Cup is on and England has managed  to make it to a reasonably important stage. When half time comes around the country may have 10 million households all turning their kettles on simultaneously  to make themselves a cup of tea. This surge, called a TV pick up, is accounted for and extra generators can be turned and surplus power created for these times.

A study has recently been published describing a similar change in electricity demand but over a much longer period. It focused on how climate change is likely going to affect the demand in the southern United States and what infrastructure changes might be required in order to satisfy this. As the temperature gets hotter, more buildings will use electrical cooling systems and this is what will really drive up the electricity usage. All new electrical construction will have to be done considering the expected demand in the future in order to prevent having to relay many cables later. Studies like this are essential for the predictions and plans to be made in order to ensure things keep running smoothly.