Friday, December 18, 2015

Reader’s Guide To Paris Climate Change Conference: Part 1

What exactly was the Paris Climate Conference 2015 about?

The heads of around 200 nations met in Paris in November- December 2015. They had a single problem to solve – how to limit the global warming and avoid the disaster in the near future. In the pre-conference discussions, a goal was decided – to limit the global warming to 2 degree Celsius.

So what’s the big deal about 2 degrees? We don’t seem to care when in summer the temperature rises by 10 or 20 degrees.

This is not the normal atmospheric temperature that we are talking about here. It is called ‘Global Mean Surface Temperature’ (GMST) of the earth. Because it’s an average of temperature at many places at many times in the year, it does not change much. As an example, the GMST in July 2015 was 16.61 degree Celsius, which 0.08 degree more that July 2014. Even this change of less than a tenth of a degree is considered large. So when someone says that the GMST is up by one degree, she is giving you real bad news.

Why is it such bad news? Just because it’s going to be hotter? I guess we can use more air-conditioners to keep cool.

The rise in GMST (also called as Global Warming) is much more than rise in atmospheric temperature, which makes us feel warm. Its effect on the climate of the earth are many, and disastrous. If we want to make a very short list, it will look like this:
  • -   Sea level rise : costal land will go under sea
  • -   Bigger and more storms, heat waves and floods : we have already seen this in last few years
  • -    Draughts and water shortage – this will probably the first and most dangerous outcome
  • -    Food shortage – due to destruction of life in the seas and on  the land

One doesn't have to explain what will be the impact of these on humankind.

But is this going to happen anytime in foreseeable future? Usually such things are millions of years away.

Not so lucky this time. Some of the effects have already started. Most of them are supposed to become full blown problems by 2100, which is going to be in the lifetime of the children born now.

Of course, the scientific models that predict these outcomes cannot be completely accurate. The climatologists are certain about the outcomes, but not so certain about when they happen. But there is a general agreement that the climate changes will happen in this century.

What is causing this temperature rise?

The primary cause of the temperature rise is the increasing amount of carbon-dioxide (CO2) in the atmosphere. The CO2 in the air traps the heat, which cause temperatures to rise. Naturally, CO2 comes from breathing of most animals and from decaying matter. The oceans and forests absorb CO2. Because of these sinks, the CO2 levels in atmosphere are maintained.

But CO2 also comes from burning what is called as fossil fuels – coal, petrol, diesel, gas and so on. Since the beginning of industrial revolution in the 1700-1800s, we are burning more and more fossil fuels. In fact since the second half of last century- from 1950 onwards- the use of fossil fuel has risen to mega proportions. The sinks cannot absorb so much CO2, so atmospheric CO2 goes on increasing. The amount of CO2 in the atmosphere is now about 400 parts per million, which is more than double of the levels in the last 20 lac years.

So is it a question of using fewer cars then?

Well, our energy requirements go much beyond transportation. We need an enormous amount of energy to run our homes, farms and factories. In cold climates, electricity is used to keep houses warm, in hotter regions, to keep them cool. Our water distribution and irrigation needs electricity. Our whole civilization is powered by energy in various forms. And almost all of this energy is produced by burning fossil fuels - as of now, 86% of energy production uses fossil fuels!

But electricity generation using non-fossil fuel sources like solar and wind is already growing. So won’t the problem be solved in a few years?

Some sources of electricity are environment friendly. The best example is hydroelectric power. Others are solar, wind and nuclear energy.

While each of these methods has problems of its own, the biggest and common problem is investment. Take for example solar energy. The setup cost to produce 1 megawatt is about 8 crores. The city of Mumbai needs around 4000 MW of energy. So the investment required to shift Mumbai to solar power will be 32,000 crores! Similar investments are required for wind and nuclear energy. Most nations are not able to make this kind of investment.

The second problem that stands in the way of shift from fossil fuels is political. Many countries and large companies are dependent on fossil fuel for their economy. These bodies naturally resist any large scale attempts to discard fossil fuel use.   

Why can’t we simply reduce our energy requirement?

Any reduction in energy use means reducing quality of life. Residents of richer nations use much more electricity than the residents of poorer nations. To give examples, a resident of the US uses around 15000 units per year (KWh), while a resident of India uses 1000 units and someone in Congo uses 100 units! As the poor nations achieve better economic status, their energy consumption goes up. In the years 2000 to 2014, China’s electricity consumption per person rose by five times! So for the developing nations, reduction in energy consumption works like a dampener on their efforts to come out of poverty.


To summarise, it is essential to reduce the burning of fossil fuel if we want to avoid a looming disaster. But reducing it is difficult because of the complexity of the factors involved. This is not a problem that one nation or a small group of nations can solve. To make any progress, the whole world has to come together. This is the rationale of the 2015 Paris Climate Change Conference.

In the next part, we will see what transpired at the conference and its outcome.

Chennai Floods - a grim reminder

The recent flooding of Chennai and other areas in southern India is a grim reminder of the power of nature’s fury. All man-made fortification come up short against the intensity of an engulfing flood. We have seen it time and again.

The post-mortem of the floods will go on for some time. Some have claimed that the opening of the water reservoirs of the dams was not managed properly. The El Nino effect (the warming up of water in the Pacific, which happens periodically) was responsible for the severe North-East monsoon in late November. The biggest reason being sited is the destruction of green cover in areas around Chennai, including the mangroves.

Our ecosystem is our first and last protection against floods. Last year I had written an article on how the ecosystem performs the all important function of flood control. Here is the link:

Saturday, October 10, 2015

The Awareness Series: Quantum Computer

Computers were invented 60 years ago. Since then they have become very very powerful, but their working principle has remained the same. Now scientists are working on a new kind of computer called the ‘Quantum Computer’. The quantum computers are based on quantum mechanics.

The quantum effect was discovered by many scientists beginning with Einstein in the first 25 years of last century. These strange effects are observed only at very small scale, like particles smaller than the atom. Some of the strange effects are superposition and entanglement.

The quantum computer is based on these effects. As a unit of calculation, it uses ‘qbit’ or quantum bit instead of the ‘bit’ that a normal computer uses. A bit can be either 0 or 1, but qbit can be both at the same time, because of the strange quantum properties. Therefore a set of qbits can do many computations at the same time.

It is not correct to say that quantum computers are faster than the conventional computers. There are some tasks- like code breaking- that conventional computers cannot do in years, but quantum computers can do in seconds. But for many other tasks, they may be as fast as the normal ones.

Even though quantum computers are in the laboratories today, rapid progress is being made in making it available in the market. I hope my dear readers of YSc would welcome the arrival of a new kind of computers first time since their invention.

Monday, October 5, 2015

Nobel Prizes 2015 – Medicine

There are two heart-warming things about the nobel for medicine this year, announced today.

It was jointly awarded to three scientists – William Campbell of US (born Irish), Satoshi Omura of Japan and Youyou Tu of China. All are now in their eighties.

The first heart-warming thing – The prize was given for development of important drugs for the diseases of the poor. Mr. Campbell and Mr. Omura discovered a drug called Avermectin that treats diseases caused by roundworms. One of these diseases is called river blindness. Another is Lymphatic Filariasis, a terrible swelling condition. Together these affect more than 10 crore people in the world.

Ms. Tu discovered a drug called Artemisinin for treatment of malaria, a disease all too familiar to us in India. It affects 20 crore people worldwide each year, especially in Africa and Asia. Thanks to Artemisinin, the death rate due to malaria in the children has come down by 30%!

The second heart-warming aspect of the nobel – both the drugs have been developed from natural sources. Avermectin from a certain bacteria and Artemisinin from a traditional chinese herb.

(To read further on how important natural resources are for development of new drugs, read my older article…/ecosystem-sciences-part-3-me…)

Yours Sciencely congratulates the recipients and thanks them for their gifts to the humanity.

Sunday, September 13, 2015

‘Kick’, holograms and the universe

In the Bollywood movie ‘Kick’ the hero, played by Salman Khan, is under tight surveillance of the police. To shake off the trail, he projects a holographic image of himself continuously pacing around the house. The police are totally deceived by the illusion, keeping a close watch on the hologram while the real hero carries out whatever admirable enterprise he has in mind.

Is this technology real? Can we create a convincing likeness of something? The answer is yes, holograms are real and as we will see, they might one day lead us to the key to the mystery of the universe.

What is a hologram? It’s like a photograph, but it is 3D and is entirely made up of light. When projected, it is so much like the original object that it even looks different from different angles.

The way holograms are created are somewhat similar to photography. They also require exposure of light on a photographic film, but making a hologram is more complex and more difficult than taking a photograph.

First, there is no lens to focus the light. Instead, the light falls directly on the film. But the most interesting part is the way light is used. The image that is captured by the film is actually a pattern created by mixing beams from two sources. Usually lasers are used for this purpose.

In your school books on physics, you must have read about ‘interference of light’. When light beams from two sources meet under certain conditions, they create a pattern called ‘interference pattern’. The pattern looks like concentric, alternate dark and bright circles. This weird effect from physics gives rise to holographs. Such is the close relationship between Bollywood and physics.

Now, every single point on the object being holographed makes one interference circle, so the film gets a strange looking pattern that is made up of innumerable such circles. When a hologram are displayed, light is passed through the film. On the other side, we see the original object in 3D, without a screen, in the empty space!

There is just one caveat, which makes the use of holograms as shown in the movie ‘Kick’ impossible. While a hologram is being made, everything has to be absolutely still. Even a small disturbance such as talking can disturb the interference pattern and make the hologram invalid. So the part about anxiously pacing around the house in the film is just that, filmy.

You must have seen holograms on your credit cards, but the are now being used for a whole lot of applications, including storing large amount of information. This area has seen a huge amount of interest from the research community as well as the technology industry.

The scientists are following a different path, though. Some scientists have argued that the whole universe is a hologram, and our perception of the things around us is created by processing the information in the hologram. This might appear strange to you, but the universe has always proved to be stranger than we can imagine. Who knows, the Holographic Universe theory might one day become the key, as we said in the beginning, to understanding the mystery that is around us

Sunday, August 9, 2015

Giving sight to the blind

Here is a device that is helping the blind to see. Retinitis pigmentosa (RP) is a disease of the eye, in which certain important cells in the eye get damaged. These cells, called photoreceptors, are responsible for converting the light into electrical signals. The electrical signals are carried by the optic nerves to the brain. The brain interprets the signals and creates meaningful patterns, in short, makes us see the world.

In patients suffering from RP, the electrical signals don’t get generated, so they can’t see even if all the other parts of their viewing equipment are in perfect order. The newly introduced Argus® II system helps the RP patients to overcome this handicap.

The Argus system has three parts. The first part is a small camera that creates an image of the world in front. The second part is a tiny wearable computer. The computer creates a suitable input for the brain from the image. The third and most interesting part is an implant that is surgically inserted into the eye. This implant receives the signal made by the computer and gives it to the optic nerves in form of electrical pulses.

When the brain gets these pulses, it interprets them and creates a vision. But this vision is different from what we normally see. So the patient has to get used to this new kind of seeing. But it is sure worth the efforts because they get their vision back!

About 100 patients in US and Canada have so far benefited from the invention, which received the USFDA approval in 2013.

While writing about the important discoveries of 2013, I described the ‘Mind Controlled Artificial Leg’, in which the signal from the brain is trapped and given to an artificial leg prosthetic.

The Argus discovery is the mirror image of the mind controlled leg, where we are preparing a signal that the brain can use. This is called a ‘sensory’ signal, as opposed to the ‘motor’ signal used for the artificial leg.

See the website of the company that has invented and is promoting the device:

Monday, July 20, 2015

Finding Nemo’s wrong biology

Finding Nemo is an amazing movie. In the movie, a fish called Marlin loses his wife and eggs in an attack by the fearsome Barracuda fish. Only one egg survives. When it hatches, Marlin names the baby fish as Nemo. Due to the painful memories of the loss, Marlin becomes overprotective of his son. But in spite of the protection of his father, Nemo ends up in a fish tank, and Marlin undertakes a heroic journey to bring him back.
Though a heart warming and eminently watchable movie, Finding Nemo has a biological inaccuracy. But before we can understand that, we turn our attention to an ancient divide – the male-female difference.
The fact that even the fish have fathers and mothers seems unremarkable to us. We take the division of any population into males and females for granted. The males and females of human beings have strong differences of body and mind, so much so that the two genders are supposed to be natives of different planets. The animals we see and recognize (mostly mammals) like dogs and cattle seem to have similar differences of gender, though we don’t actually know whether oxen don’t like to ask directions and cows are terrible drivers.
In human beings, gender is more of a social concept, defined by behaviour, role and responsibility. Most societies now recognize biological sex as different from gender. While the concept of gender is meaningful only in human beings, the biological differences in the male and female sexes are applicable to all living organisms.
But what exactly is a male or female? Biology’s definition of sex is very simple and it has to do with what kind of reproductive material the individual produces.
Sexual reproduction is basically the fusing together of two cells, each carrying only half the genetic material required. The fusing creates a cell with full genetic material, which then grows into a complete organism. This mixing of genetic properties gives sexually reproducing living beings an advantage in survival. This is the reason behind the popularity of sexual reproduction among species.
The two cells that fuse are not alike. One is very small but can move fast, the other is big, but stationary. These two cells are called gametes, and it is this asymmetry in the gametes that gives rise to the male-female difference. The smaller gamete is called sperm and the individual that produces it is called male. The larger gamete is called ovum (or egg cell) and the individual which produces it is called female.
(To set the record straight, there are species in which both the cells are alike, but we won’t talk about them here, to keep matters simple.)
Looking at the familiar world of living beings around us, we can easily make two rules:
- An individual is either a male or female
- Once an individual is a male (or female), it remains so for the whole life
So obvious these rules look, it hardly seems necessary to write them. But nature is far more innovative than that. In fact, none of the above rules is true.
Well, firstly, there are the hermaphrodites. There are many species in which an individual is both male and female. To begin with, most plants are hermaphrodites. But even if you take just the animals, over 5% of the species are hermaphrodites. The most familiar examples are the earthworms and garden snails.
Hermaphrodites don’t actually need another individual for reproduction. They can fertilize themselves, but usually they don’t, for the main reason that underlies sexual reproduction – mixing of genetic material is good for survival. Many species, especially plants, however fertilize themselves when it becomes difficult to find gametes from another individual.
Usually the biological sex is determined by the genetic material. In mammals the default sex of an individual is female. But if the genetic material contains a certain piece called the Y-chromosome, the individual becomes male. In birds, the default is male, and presence of a W-chromosome makes the bird female. The sex assigned by genetic material remains fixed for life.
Some species however use more colourful methods of sex determination. In many reptiles, the sex is determined by the temperature at which the egg is hatched. In turtles, for example, a lower hatching temperature produces a male.
But the weirdest strategy is used by the species that change sex during their life. And here’s where we meet Marlin the fish once again. The fish species used in Finding Nemo is Ocelleris clownfish, or simply clownfish. In clownfish, the smaller fish are male and the largest fish becomes female. If the largest fish is to die, the next largest fish will become female!
So in a real life plot of Finding Nemo, Marlin the father fish will become Coral the mother after the Barracuda attack, while Nemo will continue to remain male. According to published stories, this was actually pointed out to the makers of the movie, but they chose to ignore this scientific detail for the purpose of simplicity, a position I wholeheartedly support.

Monday, July 6, 2015

The mythology of the internet: world’s largest snake

For the last few days, reports and photographs of a snake 134 feet in length and weighing more than 2000 kgs are circulating on social networks. You have also probably seen these reports. They further claim that the snake is an Anaconda residing in Africa’s Amazon River; and it has killed 257 human beings and 2325 animals.
Well, well, first a small geographical correction is in order – the river Amazon is in South America, not in Africa. After this bit of geography, we can turn to the biology.
Anaconda is a genus of snakes that includes many species. All these species are found in the continent of South America. They are aquatic animals, mostly dwelling, hunting and breeding in rivers. One of the species, the Green Anaconda, represents some of the world’s longest and heaviest snakes.
However, the length and weight does not reach anywhere the figures we read in the above news. Typical green anacondas are only (!!) 20 feet in length, with weights in the vicinity of 200 kgs. Anacondas reaching 25 feet have been recorded, but no anaconda longer than 30 feet has ever been reliably found.
Python is another type of snakes whose members reach enormous lengths. They are actually longer than anacondas, but much lighter. Pythons are residents of South East Asian countries like Burma (Myanmar), Indonesia, Vietnam and Thailand.
But even longest recorded Pythons have been in the range of 25-28 feet. So, no snake in currently existing species has ever exceeded 30 feet in length.
For the above reports to be true, the snake has to be more than four times the longest snake ever known. As far as we can see, these are false reports and the photos must have been doctored.
What do you make of the claims made about the snake eating 2325 animals? Isn't it rather difficult to track the number of animals eaten by any snake, unless it is in zoo, or it has been dutifully reporting details of each of its meal to zealous internet aficionados?
Lastly, anacondas (and pythons) are known to attack human beings, but such attacks are extremely rare, no matter what you have seen in the three Anaconda movies

Monday, June 22, 2015

Review of – ‘A Brief History of Nearly Everything’

Have you often felt that there are so many things in science that you would like to know? Do you wish that there is a book about such things that is easy to read? ‘A Brief History of Nearly Everything’ by Bill Bryson is one such book.
Bill Bryson is an author of many travel books. His travelogues of England, Europe, America are highly readable and entertaining. This is his first book on Science and he writes it with the same intention as travelogues – to introduce a new land and stoke the curiosity of the reader. The reader should get excited enough to start the journey on her own.
Cosmology, Palaeontology, Relativity, Quantum Physics, Geology, Evolution, Genetics, Anthropology – do you think these subjects with scary names are best hidden in fat books kept in rusty cupboards in dusty libraries? Bill Bryson proves you wrong. These subjects can be fun too, if told in an entertaining way. Wrapped in Bryson’s words, the fearsome subjects appear like the lovable tigers in kid’s cartoons.
Bryson gives us the knowledge, but packs it in warmth and mixes with fun. For example, Bryson writes about Palaeontology, which is the study of very old things. But instead of drowning us in big words, he tells us a story of a 11 year old girl, Mary Anning. She found the fossils of a 17 feet monster animal on the sea shores of Dorset in England. She spent the next thirty five years finding hundreds of such fossils. Bryson says ‘She is commonly held as the source of the tongue twister – She sells sea shells on the sea shore.’
To make the concepts attractive, Bryson uses entertaining examples. This is what Bryson says while illustrating Einstein’s famous equation E = mc2:
‘ You may not feel particularly robust, but if you are an average sized adult you will contain within your modest frame no less than 7 x 10^18 Jules of potential energy – enough to explode with the force of thirty very large hydrogen bombs, assuming you knew how to liberate it and really wished to make a point.’ smile emoticon
Bryson unfolds the story of science through the personalities of its lead actors – the scientists. The dazzling tales of discoveries revolve around the people who made them. So the story of Physics is woven around scientists like Newton, Einstein, Rutherford and Bohr; Chemistry is linked to Mendeleyev, Lavoisier, Curie, and Geology to Hutton, Lyell.
And what colourful personalities these scientists are! We learn about the scientist William Buckland, who woke up his wife at midnight to take a footprint of a tortoise in flour paste!
Karl Scheele, a chemist, who discovered eight elements and many commercially important compounds had the strange habit of tasting every chemical that he studied. Not surprisingly, he ultimately died due to his weird culinary habits.
Women became important part of science only in the last few decades. Even in 1930, women were given simple and menial tasks. A woman called Henrietta Leavitt was employed to perform the routine task of observing photographic plates of sky. But she managed to discover the 'standard candles', which made it possible to measure distances between stars.
We learn from Bryson how glamour follows the hard work in science. Niels Bohr, who postponed his honeymoon to write a landmark paper on Quantum Leap of electron, received Nobel Prize for the finding.
For readers like us, it is always easy to like other people like scientists, and once we like them, we start liking their work too. Many a young children reading this book may dream of becoming a scientist, which will not be a bad thing at all.
It is so educating to learn that science is not infallible at all. Scientists make mistakes regularly and like ordinary human beings, struggle to defend them.
Bryson describes how the first Dinosaur bone to be found was ignored and lost. Dr. Wistar, who came in possession of the bone, failed to see its significance. It was put into a storeroom, forgotten and ultimately lost. Had Wistar given it a little more thought, he would have discovered Dinosaur 50 years before anyone else.
Perhaps nothing makes the point better than the efforts to estimate the age of earth. It took more then hundred years to arrive at the right figure and on the way there were many huge mistakes. An eminent scientist like Lord Kelvin was firm that earth is not older than 10 crore years (the actual age is 480 crore years).
But through the mistakes of individuals science continued its search. Science keeps hitting at a problem even when one entire generation of scientists gets stuck. And this is the overwhelming message that we get from the book – the ever advancing march of human knowledge. I am sure anyone who reads this book will start looking at the world through different eyes.

Thursday, May 14, 2015

Seafood and the story of evolution

Do you think that prawns are fish? If you are a fish eater, your Sunday meal may present you with the pleasant package of prawns and King Mackerel (Surmai in Marathi). Before you take the next mouthful, think about these two facts – prawns are not fish at all; and fish are actually closer to human beings that they are to prawns!
The story goes like this – prawns belong to a group of animals called the arthropods. Insects (like bees and ants) and spiders are some other kinds of animals that are also arthropods. Now arthropods is a very large group. In facts, 80% of all animals are arthropods. There are many smaller subgroups in the arthropods. We already know the insects. Then there are the arachnids, or what we call spiders. Do you know the centipedes – the round things with lots of legs? They have a group of their own, called myriapoda. And then there are crustaceans – the group of the prawns.
The crustaceans appeared on earth very early, around 50 crore years ago. There are other kinds of animals that fall in the crustacean subgroup, like crabs and lobsters. Crustaceans have mainly kept to the sea, not really showing much interest in venturing on the land.
Just like arthropods, there is another group called the chordates. It is much smaller, but a lot more important to us, because it’s the group to which we belong to.
The largest subgroup in chordates is vertebrates – animals with a backbone. All other subgroups are either very small or extinct.
After it gets here, the story becomes interesting, because it leads to us. In vertebrates, first come all the fish. Our topic of the day, the King Mackerel, is a member of a very important subgroup of the fishes – the bony fishes. About 99% of all fish belong to this group, almost every fish except the sharks. From the bony fish, it’s just three steps to us humans.
Once you leave out the fishes, most other vertebrates are tetrapods – animals with four limbs. There are only four major kinds of tetrapods – amphibians like the frogs, reptiles like the lizards and snakes, birds like the peacocks and mammals like humans. In fact, the tetrapods actually evolved from a kind of bony fish, an adventurous kind that crawled onto the land.
Can you see the picture now? Prawns the crustaceans broke away from chordates and vertebrates long time ago. But a branch of bony fish like Mackerel actually grew into early tetrapods and mammals- in turn, human beings.
So if prawns could talk, they would call us fish.

Thursday, April 16, 2015

Bacteria, scholar

Intelligence is an idea that is hard to catch in a definition. There are a million varieties of intelligence. If solving a mathematical equation is intelligence, so is deciding which spice will suit which dish. Selecting the right move in a chess game is intelligence, and choosing the right shade of colour in a painting is intelligence too. These are all high profile varieties of intelligence. But even activities that appear very simple to us require complex calculations, so scientists have realised.
One such simple but ever present activity is moving towards the target. Pause here, give it a thought and you can see that no animal can survive without this skill. Animals have to find food, which means they have to detect food and move towards it (with the possible exception of the lucky animals who can order food at home).
Detecting food and moving towards it requires high degree of intelligence – we just don’t recognise it because we take it for granted. Take mosquitoes for instance – they find you by smell. Or take ants and bees, which have an army of food finders and use elaborate signals to tell others that they have found it. Bats use ultrasound waves to detect their food – a mechanism called Echolocation which is so complex that when you understand it you will treat the mouse like creatures hanging from a neighbourhood tree with definite respect.
But the hero of this article is an unlikely candidate – bacteria. A primitive living being, neither animal nor plant, and visible only through very powerful microscopes. Let alone a brain, it does not even have a neuron. But with the limited means at its disposal, it does a wonderful job of moving towards its food. Bacteria were the first form of life on earth, they are still around, and most probably they will be there when we humans take our exit, which means they are finding their food alright. The mechanism they use for moving towards their food is so basic, yet so fantastic!
Dip a thin glass tube in a jar of water and pass a bit of glucose through the tube. The bacteria in the water will move and reach the tube to eat the glucose. A bacteria is really really small - 1000 bacteria can sit side by side in one millimetre mark on your scale, without the slightest discomfort. So even detecting glucose one centimetre away is like you detecting a freshly fried Batatawada from ten kilometres. How do they do it? They don’t even have noses.
Glucose, like everything else, is made up of molecules. The molecules are much smaller than the bacteria. As we drop glucose in water, these molecules spread in water, some finally reach the bacteria.
What happens next is an arresting sight, if only you can zoom it by a billion times. When the glucose molecules reach the cell wall of the bacteria, they act like a key for a lock. What does the key-lock mean here?
On the cell membrane of the bacteria, there are special sites, like our airstrips, for the glucose molecules to land. But the shape of these sites is such that only some molecules can land there. This is why I called it a key-lock mechanism.
Once the key is in the lock, the membrane opens a little bit. Certain ions from the outside liquid (like calcium or sodium) enter into the cell. (Ions are electrically charged particles that are present in all solutions.)
These ions enter in style – like a bollywood hero entering a villain’s den, and create the same kind of brisk activity. The end result of this activity is moving the small hair like extensions on the wall, called cilia (search ‘Cilia bacteria’ in Google and see the images). The movement of these cilia propel the bacteria in the right direction, like a rowboat.
But how does the bacteria know where to go, where the glucose source is? The bacteria does something very clever. It moves in a zig-zag motion, which we human beings can reproduce by drinking large amount of alcohol. But the bacteria is merely sensing the number of glucose molecules in its path. The direction in which the number of molecules of glucose goes up is the direction of the source. If it finds lesser molecules as it moves, it’s wrong direction, so it comes back and tries another direction.
Isn’t it fascinating? It tells us at least two things. First, the things at small scale are as spectacular as those we can see. Second, behaviour that appears intelligent can be produced purely by chemistry.

Sunday, April 12, 2015

100 Words – Life in the sea is in danger

We burn a lot of carbon – like petrol, diesel, coal and gas for our energy needs. This makes huge amounts of carbon dioxide (CO2) – 36 billion tonnes in 2013. Half of this CO2 dissolves in the oceans, just like we make our fizzy soft drinks. A small part of it generates Hydrogen ions (H+) – Hydrogen atom minus the electron. The concentration of H+ in oceans has gone up by 30% in last 250 years of industry. This increased concentration of H+ is killing creatures like sea snails. The impact will be on bigger animals in sea and land, including us.

Wednesday, April 8, 2015

Of tortoises and school buses

This article is for the students, especially those who are enjoying a peaceful life after the board exams. If you belong to this lucky group, you might want to spend a little time reading this bit of wisdom from the past. It’s actually like a cool FB post, only about 2500 years old, by a guy called Zeno. Make friendship with Zeno now and he might help you in college, with all the math’s stuff you are going to find there.
2500 years ago, around the same time Buddha was preaching in India, the little country of Greece was teeming with all kinds of scholars. They had no FB and WhatsApp to share their status updates, but their teaching was earnestly learned and kept alive by their students. One such scholar was Zeno.
Zeno liked giving strange little problems to others. He told people to imagine a race – a race between a tortoise and a young man called Achilles. I mean, isn’t this like your school cricket team against Australia? Everyone knows how this race will end. But Zeno gave them a different story. It goes like this:
Suppose Achilles is ten times faster than the tortoise. To make the race fair, let’s place the tortoise 100 meters ahead of Achilles.
Let the race begin.
First, Achilles has to run the 100 meters. The tortoise is ten times slower. So it will run 10 meters while Achilles covers the 100 meters gap. Now there are 10 meters between them.
Next, Achilles has to run 10 meters. In this time, our tortoise is going to run 1 meter.
Achilles does not take long to run 1 meter, but tortoise has raced ahead by 10 centimetres!
Take out a forgotten notebook now, and try to write the next steps in this story. Well, you will finish all the notebooks, but this story will never end. No matter what you do, the tortoise will remain a little bit ahead. Achilles will never overtake the tortoise.
But we know Achilles actually overtakes the tortoise in real life. Such things are called Paradoxes. A Paradox is something you know to be false, but you can’t point out what is wrong with it.
There is another way in which Zeno’s Paradox is told. Suppose your school bus is standing 100 meters from you. You have to run and catch it. Now, to cover the 100 meters you have to first run 50 meters. Now only 50 meters remain. But before you run 50 meters, you have to go 25 meters. You run half the distance, but half still remains. No matter how much you run, a tiny bit will still remain. This means you can never catch the bus, even though it is standing still! But in real, you do catch the bus, almost everyday. That's what a Paradox is.
When scholars see such Paradoxes, their eyes light up. ‘Let me try my hand at this now’, they say to themselves. And so over the years, many clever people have tried to answer Zeno in their own way. Some fellows have applied mathematical ideas to the problem. You will probably like one of these ideas - it’s called a ‘convergent series’.
To understand convergent series, let’s go to the school bus again and try to cover the 100 meters. The distance you cover first is 50, then 25 and so on. Let me write it down:
50, 25, 12.5, 6.25, 3.125, and many more. To get the next number, just make half of the last one.
Let’s add all these meters that you ran:
50 + 25 + 12.5 + 6.25 + 3.125 + ...
(These three little dots at the end mean -‘Picture abhi baki hai’, or the story does not end here, there are going to be many such numbers).
What do you think the total of all these numbers will be?
Remember that you were 100 meters away from the bus? So the total will never be more than 100. But it will never be exactly 100 too. See for yourself:
Can you calculate the next totals?
You are going to meet these funny convergent series in college. The method to find totals of such series is called Integration, and once you master integration and things like that, there is no stopping you. One day you will possibly build a Jupiter Mission for India.

Saturday, April 4, 2015

Prime numbers and credit cards

This article is about prime numbers. What! Skipping already?? I know you had enough of them in school and would like to get over the painful memories now. But can you hang on for a few more lines please? I am going to tell you two or three simple things about primes that will tell you a lot about security on the internet.
As we all know, prime is a number that can be divided by only two numbers – one (1) and that number itself. 31 is a prime number, because you won’t find a number- other than 1 and 31- that can divide 31. In other words, no multiplication table contains 31.
How do you decide that a number is prime? It’s easy, but completely donkey work. Take 31. You have to carry out the following steps-
- Is it a multiple of 2, if not,
- Is it a multiple of 3, if not,
- Is it a multiple of 4 ....and so on, all the way to
- Is it a multiple of 30?
If you a get a Yes to any of the above question, stop – it’s not a prime.
Now for a two or three digit number, you can work it out if you have nothing else to do, now that the world cup is over. For larger numbers, like 5437629789890011, you can use a computer to test its Primality, which is just a fancy name for being a prime.
For the computer nerds, this has become a kind of game. Since even computer take really long to test immensely big primes, the geeks run a race to find faster methods of testing primes. The largest prime found so far has 17,425,170 digits!
Now let’s take two primes and multiply them. What do we get? A larger number, of course. For example – 5 X 3 = 15. Easy enough.
But what if I give you 15 and ask to find the two prime numbers that made it in the first place? You can do it, it’s only a little trial and error. You find 3 and 5, and we call them the prime factor of 15.
But what if I give you 10873 and ask you to find its two prime factors? You wouldn’t try it, even if you have a long weekend ahead. You would turn to the computers and they will find the factors for you – 83 and 131.
Now let’s twist this a bit and make the computers groan. Take two large prime numbers, multiply them – you will get a very big number. Give this to the computer and ask it to find the prime factors.
It will huff and puff. Even very powerful computers will take a long long time to find the factors. If you give the most powerful computer existing today a 300 digit number, it will take more time than the age of the universe (13800 crore years) to come up with the result, and it will be a decidedly tired looking computer.
Some clever people used this fact to design a scheme for security of data on the internet. When you put your credit card number on Flipkart or Jabong, it is sent over the wires. It can actually be intercepted and read by anyone snooping on the way. This snooper will obviously then become quite comfortable in life, buying clothes, sofa and books on the internet. But it doesn’t happen. And the reason why this doesn’t happen has to do with what we just learned about prime numbers.
The basic technique (called RSA encryption) is very simple. When you put your credit card number, it is coded and changed beyond recognition before sending over the wires. The coding uses a very large number. When the coded credit card number reaches Flipkart (or Amazon, or whatever...), it is decoded back. But this decoding requires two prime factors of the original large number.
Now you see how clever it is? Anyone can find the public large number. But it does not help you. If you want to decode, you will need its two private prime factors. Finding these factors, as you seen, takes forever, so no one even attempts it.
Overall it is a pretty satisfying scene, isn't it? But wait....something is going to soon spoil the party. It’s called the quantum computer. Quantum computers are not yet really here, but when they come, they will crack a 300 digit RSA code in- hold your breath- less than 4 minutes!
It’s not just about credit cards. Most international top secret communications today use RSA encryption. Quantum computers will render them about as secret as writing on a postcard.
But what is a quantum computer? For that we will have to wait for a future article.