The Gist of Science Reporter: May 2015

The Gist of Science Reporter: May 2015

  • Scientists Discover How Birds Localize Sound Sources (Free Available)
  • The Importance of being “Stupid” (Free Available)
  • Questioning in Science: Implications and Consequences (Only For The Subscribed Members)
  • Greatest Discovery of Nineteenth Century (Only For The Subscribed Members)


A research team in the College of Literature, Science and the Arts University of Michigan, has reported in Science [2014;346 (6214): 1208 DOl: 10.1126/science.1250366] confirming several properties of the compound called Samarium Hexaboride, an iridescent material whose properties had puzzled scientists since the 1960s.

The material turns out to be an exotic state of matter that may be used to create next generation electronics like quantum computers. Their results confirm how to classify the material and provide the first direct evidence that samarium hexaboride, 5mB., is a ‘topological insulator’. Topological insulators are a class of solids that conduct electricity like a metal across their surface, but block the flow of current like rubber through their interior. The University of Michigan scientists used a technique called ‘torque magnetometry’ to resolve the ‘Fermi surface topology’ by observing the material’s oscillations in a magnetic field when an electric current moved through it. They found that Samarium Hexaboride had a two dimensional conducting surface. Their technique also showed that the surface of samarium hexaboride holds rare Dirac electrons, particles that may be useful to Samarium Hexaboride help researchers overcome one of the biggest hurdles in quantum computing. Electrons in SmB6. interact more closely with one another than most solids. This helps its interior maintain electricity-blocking behavior. Engineers might one day route the flow of electric current in Samarium Hexaboride, a strongly ‘co-related material’, so it could be used in quantum computers much like silicon in conventional electronics. In quantum computers, “qubits” stand for the 0s and 1s of conventional computers’ binary code. While a conventional bit can be either a 0 or 1, a qubit can be both at the same time. However when you measure the quantum system it forces it to choose one state, 0 or 1 eliminating its main advantage. They now hope to overcome this flaw by using Samarium Hexaboride to create quantum transistors.

Scientists Discover How Birds Localize Sound Sources

Because birds have no external ears, it has long been believed that they are unable to differentiate between sounds coming from different elevations. By studying three avian species - crow, duck and chicken - Schnyder discovered that birds are also able to identify sounds from different elevation angles. It seems that their slightly oval-shaped head transforms sound waves in a similar way to external ears.

It all comes down to the shape of the avian head. Depending on where the sound waves hit the head, they are reflected, absorbed or diffracted. What the scientists discovered was that the head completely screens the sound coming from certain directions. Other sound waves pass through the head and trigger a response in the opposite ear.

The avian brain determines whether a sound is coming from above or below from the different sound volumes in both ears. “This is how birds identify where exactly a lateral sound is coming from - for example at eye height,” continues Schnyder. “The system is highly accurate: at the highest level, birds can identify lateral sounds at an angle of elevation from -30° to +30°.”

Why have birds developed sound localization on the vertical plane? Most birds have eyes on the sides of their heads, giving them an almost 360· field of vision. Since they have also developed the special ability to process lateral sounds coming from different elevations, they combine information from their senses of hearing and vision to use effect when it comes to evading predators.

The Importance of being “Stupid”

The importance of stupidity in scientific research’, is indeed an eye-catching title. Published in the Journal of Cell Sciences (121, 1771; 2008), the author Martin A. Schwartz, a microbiologist at the University of Virginia, provokingly says: “Science makes me feel stupid .... in fact, that I actively seek out new opportunities to feel stupid. I wouldn’t know what to do without that feeling.”

Endorsing the sentiment, physicist Brian Cox says: “I’m comfortable with the unknown-that’s the point of science. There are places out there, billions of places out there, that we know nothing about. And the fact that we know nothing about them excites me, and I want to go out and find out about them. And that’s what science is. So I think if you’re not comfortable with the unknown, then it’s difficult to be a scientist... I don’t need an answer. I don’t need answers to everything. I want to have answers to find.”

When it is unknown, then everyone, you me or Einstein are ignorant. As Schwartz observes, “Focusing on important questions puts us in the awkward position of being ignorant.” But then “one of the beautiful things about science is that it allows us to bumble along, getting it wrong time after time, and feel perfectly fine as long as we learn something each time.”

Schwartz further says “no doubt, this can be difficult for students who are accustomed to getting the answers right and argues that science education can do well if we do not exclusively harp on “learning what other people once discovered to making your own discoveries”. Schwartz goes on to celebrate being constructively stupid, “The more comfortable we become with being stupid, the deeper we will wade into the unknown and the more likely we are to make big discoveries.”

There are millions of questions out there for which we have no answers today. Be it mundane, ‘How does a bicycle work’; or profound, ‘What is time’. But there are questions galore all around us. There is a wide wonderful world out there to be discovered and made sense of. With this selection of ten enticing question we invite you to the world of the curious.

Imagine a brick lying on an open ground. Suddenly the brick animates and makes copies of itself – two, four, eight, and so on. The growing numbers of bricks then start to form structures; initially the floor, then the four walls, then windows and door opening and at last the roof. One after another the apartments are made stacked on the sides and above. Eventually a skyscraper with hundreds of floors and thousands of apartments stands on the field. Sounds plausible?

But that is what happens when the single fertilised cell grows in to a bubbly baby. Initially, at the time of conception, there is just a single fertilised cell in the human womb (or in the womb of any animal). Then the cell multiplies and proliferates. At some point of the embryo growth, the front and back are de-marketed in the blob of cells. The head develops in the front, and the legs come out from the back. The entire human child is shaped slowly like the magical brick replicating and producing a hundred- storey skyscraper.

How does it happen? How does a cell know how to make a human (or any other mammal)? Bricks on the field cannot by themselves build the whole edifice without a mason and a plan. But unlike the bricks, cells have DNA which have codes for the preparation of amino acids and production of proteins, the building blocks of the organism. However, each cell has the same genome and the eye cell differs from skin cell not because they have different genomes, but because different sets of genes are expressed.

Certain species of tortoise live for 300 years, while certain varieties of Mayflies are alive for just a few minutes. Why do animals live as long as they do? What determines their natural life span?

We know from the second law of thermodynamics, decay is natural. Red blood cells decay and are replaced once in every 120 days; the stomach wall is replenished every three days. The lungs are at the best six weeks old. The DNA, in every single cell, is damaged by free radicals and cap’s on chromosomes, the Telomeres, shorten with every cell division. When the length of the Telomeres becomes shorter than a certain length, after a certain number of cell divisions, apoptosis, or cell death occurs. But what determines the natural life span of every species? One theory says that larger the species, the slower its energy-delivery systems, the lower the metabolic rate, the longer the life. If one plots the metabolic rate against the longevity the resultant graph is almost a straight line.

This has resulted in what is popularly called the ‘one billion heart-beats’ theory. Although not to be taken literally, it says, every organism has a life span of one billion heart beats. The rat with high heart beat rate of 420 per minutes has an approximate life span of about four years while a blue whale with just six times a minute lives around 80-90 years to have the ‘one billion heart beats’. Similarly, the horse with 38 bpm (beats per minute) lives around 60 years, whereas a rabbit with 205 bpm has a life span of about 9 years. Despite a difference of many millions in body weight, heart weight, stroke volume, and total blood pumped per lifetime, the total oxygen consumption and ATP usage per unit mass and lifetime are almost identical together with the total number of the heart beats per lifetime.

Thus, it appears that all living creatures have about the same amount of energetic life, with one particular exception. Humans and our evolutionary cousins primates are outliers in an otherwise almost neat graph. For the rate of heart beats that we have, we seem to be living longer than we should be. A typical human cell contains more than 6 feet of tightly packed DNA. But only about an inch of that carries the codes needed to make proteins. Is there any relevance for the remaining 71 inches of DNA in each and every cell of our body?

Way back in the 1970s, Nobel laureate Sydney Brenner flippantly called these non-coding parts as ‘junk DNA’ and the name stuck. Are these so-called junk DNA really just trash or an invaluble treasure? Earlier, some scientists thought that these vast terrain of dark DNA consisted of genetic parasites that copy segments of DNA and paste themselves repeatedly in the genome, like computer viruses.

Perhaps, junk DNA are protective butters against genetic damage and harmful mutations. For example, at the time of chromosomal crossover event, the buffer of junk DNA may protect the functional DNA from being destroyed. Thus, the species may become more tolerant to the mechanism of genetic recombination. On the other hand, an experimental study on mouse shows that even artificially removing 1% of the junk did not result in any detectable phenotype changes. Thus, it is possible that junk DNA may indeed be trash.

Why do we Sleep?

We all need a good sleep. We spend almost one third of our life in sleep; even a night’s sleep deprivation makes us sluggish, hungry, emotional and unable to concentrate. Sleeplessness makes us forgetful, slows the reactions and affects decision making and at times vision. Most adults require about 7-8 hours of sleep to feel rested and refreshed upon waking. For infants, the requirement is much higher - about 16 hours a day, and teenagers need on an average about 9 hours of sleep. As people age, they tend to sleep more lightly and for shorter times, although often needing about the same amount of sleep as in early adulthood.

However, it must be noted that there are significant differences between the sleeping patterns of different types of animals. Although sleep or at least a physiological period of quiescence occurs in animals ranging from fruit flies to humans we do not know why we sleep.

We know what happens when we sleep. Sleep is the time when our bodies repair tissues and perform other maintenance activities. It is well established that it is during sleep time that the brain glycogen is replenished, which is consumed during the waking hours. While it is the lymphatic system that flushes out the waste produced by cells from the rest of the body, the brain is disconnected from this system. The brain has its own cleaner, cerebrospinal fluid, which collects the waste products and toxins from the brain flushing them down to the liver for excretion. During sleep it is found that the neurons in the brain shrink, permitting the cerebral fluid to move faster.

The restorative nature of sleep appears to be the result of the maintenance activities, such as cleaning toxins and consolidating memories. But why sleep emerged in the first place is still a mystery. In the wild, a sleeping animal is like a sitting duck - an easy target for the prey. Evolution should have eliminated ‘sleep’ which is a hurdle in survival. Nevertheless, most animals sleep, which implies there must be some evolutionary advantages that outweigh this considerable disadvantage. Researchers point out that it is only those animals that can hide well, that have the luxury of deep slumber. Other organisms have to remain alert at all times. Therefore, some animals sleep with one part of the brain alert while the other half is in sleep mode. After some time the other part slips into sleep, while the first part wakes up. This explains ‘how’ sleep is managed, but not when and why sleep evolved.

In our solar system, planets orbit around the Sun according to Kepler’s law. Mercury which is closest to the Sun has an orbital velocity of about 48 kilometers a second, whereas Neptune which is far away has an orbital velocity of just 5 kilometers a second. Galaxies are made up of billions of stars. As the galaxies rotate, the stars at the edge should be rotating slower, like Neptune, as compared to the inner stars, like Mercury. While this Keplerian motion is what we expect, observations show that the stars at the edge of the galaxies are rotating faster than what they should be.

Unless we assume that laws of gravity are different in other galaxies, we are left with no option but to conclude that there is some kind of mysterious ‘dark matter’ engulfing the galaxies. Totally invisible to telescopes and the human eye, dark matter neither emits nor absorbs visible light (or any form of electromagnetic radiation). At that time, mainstream astronomers scoffed at the idea and Vera was shunned for many years. Ultimately, with improved instrumentation, when rotation curves of many more galaxies and galactic clusters were precisely measured, the anomalous rotation curve became evident. Vera Rubin’s ideas are now accepted and an intense search has been mounted to discover the dark matter.

Of all the great mysteries of science today, dark energy might be the most enigmatic of all. While dark matter makes up an estimated 80% of all mass, dark energy is a hypothetical form of energy believed to make up around 70% of all content in the Universe. The neat picture was shattered when supernovae were observed at anomalous distances. Tn 1997, astronomers Schmidt and Riess observed a supernova that appeared to be further away than where it should have been. This implied that the cosmos was lot bigger, and had expanded beyond what it should have. That means the gravitational pulling power of the universe was somehow being overwhelmed. Some energy was pushing the universe against gravity and making the expansion of the universe to speed up.

The Sun’s core is really hot. Due to thermonuclear fusion taking place at the core, the temperatures are estimated to be about 15 million kelvin. As this energy slowly percolates above due to convection and convention, the surface of the Sun is heated up and shines at about 6000 kelvin. Beyond the surface enveloping the Sun is a very low density ‘atmosphere’, called solar corona. On a normal day, solar corona is not visible to the naked eye. The brilliance of the sun hides it from our view. However, during the totality of the total solar eclipse for a brief few moments, the visually enthralling solar corona can be seen. Way back in 1939, two astronomers Grotrian and Edlen studied the solar corona during a solar eclipse with a spectroscope. They found that the spectral lines of elements such as iron (Fe), calcium (Ca), and nickel (Ni) in the corona were in very high stages of ionization. This implied that the coronal temperatures should be around one million Kelvin.

In earlier times, acoustic waves were considered as a serious contender to explain the solar coronal heating. However, studies in the past have eliminated that possibility. Today two dominant theories exist to explain this mystery. One attributes the heating to the loops of the magnetic field, which stretch across the solar surface and can snap and release energy. Another ascribes the heating to waves emanating from below the solar surface, which carry magnetic energy and deposit it in the corona. Observations show both these processes continually occur on the Sun. Until now, scientists have been unable to determine whether either one of these mechanisms releases sufficient energy to heat the corona to such high temperatures.

Which Freezes Faster-Hot or cold Water?

Mpemba was an unassuming but observant Tanzanian student. Mpemba was on his way to a cooking class; that day he and his friends had to make ice cream. Unfortunately the water with which Mpemba had to prepare the mixture was warmer than his friend’s. As there was no option, both of them made the mixture and put them inside the refrigerator to freeze. After sometime, when they opened the refrigerator, to their utter surprise they found that Mpernba’s warmer mixture had turned into ice much faster than his friend’s.

Water is H20 - the two atoms of hydrogen and oxygen form a standard covalent bond. As the three atoms make an angle of about 104.5 degrees, the H-O-H appear like Mickey Mouse with two protruding ears. In fact, in this arrangement, the two ears of the Mickey Mouse, that is hydrogen atoms, .and the chin that is oxygen atom, are respectively positively and negatively charged. As both the positively charged H atoms in the molecule are sticking out like two hands, they attach to another molecule’s negatively charged oxygen atom. This bond is weak and is called the hydrogen bond. It is due to this additional bonding that the boiling point of water is higher than the liquids of similar molecules.

Xi thang says that hydrogen bonds bring water molecules into close contact and when this happens the natural repulsion between the molecules causes the covalent O-H bonds to stretch and store energy. But as the liquid warms up, water molecules move further away and it is the hydrogen bond that stretches. As the molecules sit further apart in a warmer liquid, inter-molecular repulsion would be a little less than room temperature water. Therefore, unlike molecules at room temperature, the warm water molecule’s covalent bonds can shrink again and give up their energy. The important point is that this process in which the covalent bonds give up energy is equivalent to cooling.

Yet this theory is not accepted by physicists as complete. Physicists expect that they need to use this theory to predict a novel measurable property that would arise out of shortened covalent bond, which would otherwise be not present. Until then, for physicists, it is just a good hypothesis.

Perhaps Xi is correct; but we are not sure, as of now. Nevertheless, the Mpemba effect is a great example of how a seemingly simple phenomenon is actually harder to explain once you delve into it.

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