About Me

My photo
Science communication is important in today's technologically advanced society. A good part of the adult community is not science saavy and lacks the background to make sense of rapidly changing technology. My blog attempts to help by publishing articles of general interest in an easy to read and understand format without using mathematics. I also give free lectures in community events - you can arrange these by writing to me.

Friday, 17 August 2012

Announcing Population Growth and Sustainability Talks in September 2012...

In partnership with Glasgow University and Scottish Enterprise, Lanarkshire, and following the initial announcement of the planned talks
I can confirm that I have arranged

four talks lasting 90 minutes each on
Saturdays 8, 15, 22 and 29 September 2012. 
Talks start at 11 am and end at 12:30 pm. The venue is
James Watt Auditorium, E.K. Technology Park, G75 0QD
with ample free parking on site. 

The talks are free to attend and require no science background. 
The talks are particularly suitable for school pupils and general community. 
Everybody is invited to the discussion of this highly relevant subject -
Talks promise to be informative, exciting, somewhat controversial and I am sure will be followed by thought-provoking exchanges.

The contents of the talks are:

Talk 1:  Population: Exponential Growth and Ecosystem Response
Talk 2:  Managing Climate Change:  Oceans and Atmosphere
Talk 3:  Managing Food and Water Resources
Talk 4:  Managing Energy Resources 

For further information and if you wish to express interest in attending the talks then write to 
Come along to the talks and support the popular community education initiative. 
Inform your family, friends, neighbours about the talks - it is your programme.

Thursday, 16 August 2012

Explaining Exponential Growth - its basic features...

One can find examples of Exponential Growth (EG^) in almost all fields of life.  EG^ mathematically describes how some fundamental attribute of a system will change with time.  Systems with EG^ can show non-intutive bizarre behaviours and makes exponential growth a difficult concept to comprehend and accept its conclusions.  
Mysterious as it may sound, an understanding of EG^ is crucial to appreciate what is going on in our daily lives and to plan for the future.

From calculating the interest earned on your capital to using Moore's Law to predict the number of transistors on a chip, or to calculate the power output in a nuclear reactor, EG^ is there to help. Its twin brother, exponential decay (ED^) only differs in the direction of change but shares all the concepts of EG^.

There are three ways to describe EG^ - they are equivalent but one is used in preference to others depending on the situation:  In EG^

1. Rate of change (% Change) depends on the amount present. e.g. 
Annual interest rate is 5% (interest earned per year is 0.05 times the money at the start of the year). 
Inflation index which measures the % change in the cost of a basket of goods over a year, was 2.5%. 
Global population increased by 1.4% per year in the 20th Century.
E.Coli colony increases is size at 3.5% per minute.  etc...

2.  The quantity present doubles after a certain time.
(Doubling Time) 
If you leave your money in a bond, it will double in 14 years
Inflation will double the cost of goods in 28 years.
Global population doubled every 50 years in the 20th Century.  
E Coli colony doubles in size in 20 minutes.  etc...

3.  Doubling steps: 
Accumulate something with the added amount doubling in successive steps.

The only important parameter in exponential growth is
% rate of change or doubling time. 
Rate of change and doubling time are measured in the same units of time - be it years, minutes, seconds, centuries, nanoseconds or whatever. 
They are simply related as follows (called the rule of 70):

% rate of change = 70 divided by the doubling time, and of course
The doubling time = 70 divided by the % rate of change

If we start with 1 unit and the doubling time is T then at time

10T the number of units will be 1,000 (actually 1024)
11T                                          2,000
20T                                              1,000,000
30T                                              1,000,000,000
40T                                                 1,000,000,000,000 
41T                                                 2,000,000,000,000
What quantity (population, money, no of transistors) and  the unit of time (years, seconds, minutes etc.) you choose  depends on the problem.

The thing to note is that at 10T after one doubling time, the growth was 1,000;
while at 40T after one doubling time, the increase was 1,000,000,000,000 - a billion times greater. 
This is true of all systems showing exponential growth - this is simple maths.

Also note that in each doubling time, the increase is as much as has happened in all the previous doubling steps. 
So when we say that energy consumption will double in 40 years; it means that in the next 40 years we shall consume as much energy as we have used since the beginning!  To make it clearer:
From 1970 to 2010 we used as much energy as we had used from 1800 to 1970.  (1800 is used as a reference point - energy used before 1800 was very small)

If we were to plot the quantity against time then the graph will show very little change in the beginning but after 10 or 20 doubling times the numbers would have grown to thousands of times bigger and the graph will show an almost vertical swing.

Another interesting property of EG^ graph is that it looks the same no matter what section of the graph you are looking at.  For example, in the picture, you can change the x-axis (time axis - doubling steps) from the current range of 0 to 14 to a range from 20 to 34.  The y-axis (quantity) will be changed to start at 1000,000 (the actual value at 20 doubling times) and go to 4,000,000,000 (at a doubling time of 34).  The curve on the graph will be exactly the same. 
Isn't that wonderful?

Here is a chart of how world population grew in the past 

Wednesday, 15 August 2012

Human Population Dynamics on a Finite Earth....

Growing human population with its habit of over consumption on a planet with finite space and resources provides some fascinating scenarios.   Population quadrupled in the 20th century.  The momentum of population growth will almost certainly take us from 7 billion in 2011 to over 9 billion by 2050. 
Where do we go from there?  the situation is serious enough that I shall deliberately make some provocative statements to start a serious debate.  We need to look at the big picture and come out of the habit of theoretically solving a local limited problem and announce that as a solution to everything.

In examples  1 and 2  we set out the nature of exponential growth.  Example 2 is directly applicable to human population on earth for which the doubling period is not one week (as it was in example 2) but somewhat longer - 50 years in the 20th century and may be of the order 100 years in the 21st century.  The increase in doubling period might partly be a result of humans hitting the earth's resource ceiling although many experts think that we reproduce less as we grow richer and doubling in numbers takes longer.  Some even feel that if we all got much richer then population will start decreasing.  Let me explain the problem with this line of thinking:

On average, about a quarter of us are living very well - are rich.  One third of us (China and India with a combined population of 2.5 billion) would like to increase consumption seriously to reach at least the European levels.  The remainder live at or below subsistence levels.  Currently we use resources in excess (1.5 times) of what is considered sustainable.  To raise every body's standard of living to European level will require resources of 4 Earths; to reach US levels will require 15 Earths.  And we are talking about 7 billion population.  Consumption by 9 billion rich humans will be correspondingly greater.

Look at it another way:  To support US style living for everybody on earth, we need to reduce our numbers by a factor of 15 - the population can only be about 500 million.  The reproduction rate will be no problem according to experts when we are all rich but how do we reduce the population to 500 million.  Please send me an e-mail (ektalks@yahoo.co.uk) if you think I have missed something here.
The conclusion I draw is that we have already hit the resource ceiling and increase/decrease in human population will now be governed by the resource limits of our ecosystem. 
It is not possible for our visionary world leaders to make the 7 billions of us rich quickly.

Some say that science and technology will solve the resource problems.  NanoTechnology (NT) will produce limitless food without waste, will be nonpolluting, even clean up past pollution, etc. etc...  
NT will also improve medical care, may be even allow people to live for ever (much longer than 100 years would not be unreasonable); thus decreasing the death rate drastically.  Population growth is the difference of birth rate minus the death rate.  For stable population birth rate must be zero if nobody dies.  Imagine a world full of 100 year old rich people.  Who will do the work?  Robots probably?  But then will these robots no get fed up with humans and decide to do something about it - after all they will think logically!  Now this is the subject of my blogs in 2013. 
Let us go back to human population scenarios:

The reason I think zero or negative population growth is not possible is the way exponential growth works.  This was explained in example 2.  We looked at doubling steps.  Even if 99% of the population dies the remaining 1% will grow back to original numbers within 7 doubling steps - 350 years in the case of humans.  What this means is that if a natural or human generated catastrophe eliminates 99% of the population - it will be 7 billion again in 350 years.

Nations of the world do not all think the same way.  Population, largely poor, in African and South American (A&SA) countries is doubling in 25 years or less.  Rest of the world might stabilise its population but in 100 years, A&SA will have increased their population by a factor of 16.  India's population is projected to reach 1.6 billion in 2050 from 1,2 billion now.   Indigenous US population is not expected to grow but to do the work they will allow 100 million new immigrants over the next 40 years who will demand US style standard of living.  Effectively US population will grow by more than 25% over the next 40 yaers. European population trends will not be much different from US - I believe.  It seems clear to me that eventhough local population in rich countries does not grow by itself, new immigrants will boost the population - and the arguments about reproduction rates decreasing with prosperity do not hold out - unfortunately.

So where do we go from here - if global population continues to incrase with a doubling period of 100 years then in 1000 years (10 doubling periods) the population will hit a number of 7000 billions.
what it means in terms of space and resources is quite obvious.  As I had said previously - it won't happen.


Tuesday, 14 August 2012

Population and Exponential growth ... (part 2)

Exponential Growth produces some surprising results. 
The next example has been discussed in different forms - I prefer my version.

A clump of alien life (A.L) falls on Earth in the middle of an abandoned wall garden somewhere in Italy. 
It can grow by using energy from the Sun and gases from the atmosphere - doubling in size every week.  It is bright orange in colour so easy to see, and spreads in a single layer to maximise energy capture. And, 
It can be killed by spraying coke.  

Let us assume that by the end of 40th weeks, A.L had covered 1/16th  or 6.25% of the surface area in the walled garden  
By the end of 41st week, the area covered has increased to 1/8 - 12.5%
By the end of 42nd week, the area covered has increased to 1/4 - 25%
By the end of 43rd week, the area covered has increased to 1/2 - 50%
By the end of 44th week, A.L fills the whole area in the walled garden!

Notice that it took A.L 40 weeks to occupy the first 6.25% of the garden (and during the first 40 weeks of observation, the garden would have looked relatively free from alien life) but in the next 4 weeks A.L occupied the remaining 93.75% leaving no free space.

In 4 weeks, the unoccupied area reduced from 93.75% to 0%
In the last week, A.L added as much area as it had done since the start.

Getting worried by the spread of alien life, coke was sprayed killing 99% of A.L
1% of A.L, that survived, grew as before doubling every week and in just over 6 weeks it had covered the whole area again.

Cloudy weather would prevent Sun reaching A.L and reduce its growth rate to say half - A.L doubling every two weeks. Then A.L will take 88 weeks to cover the garden.  The growth rate could vary from one week to the next and an average rate will prevail.  Different parts of the garden could grow at different rates but again an average rate will determine how long it takes A.L to cover the garden.

Extinctions, variable rates, geographically different rates etc. only affect the time it takes to cover the garden - end result is the same. 
What matters is the number of doubling periods.

Remember 1 grows to 1000 (actually 1024) after 10 doubling periods
1 grows to 1,000,000,000 after 30 doubling periods
1 grows to 1,000,000,000,000,000 after 50 doubling periods; that is 1000 trillion.
Rule of thumb is that numbers increase by 1000 after 10 doubling periods.

Exponentials, % Growth Rate, Doubling Time...

The dynamics of money supply, debt, inflation, population, energy use, digital electronics, green house gas concentrations, bacterial colony growth, radioactivity and many many other phenomena show exponential behaviour.

The science is so simple to comrehend but the consequences can be totally counterintutive, fascinating, baffling and many a times frightening.
And it always starts with a nice slow pace gaining momentum as it goes along and before you know it, it has become a monster.

Let us start with a couple of fun examples; I use them as party games:

1.  Take a big sheet of paper - normal paper is 0.1 mm thick.
      Fold it 1 times - the thickness of folded paper will be 0.2 mm.
      Fold it again - the thickness is now 0.4 mm.
      Fold is again - the thickness is now 0.8 mm.
     continue this folding for a total of 50 steps
     What do you think the thickness of the folded paper will be??

   The height of the folded paper will be more than 100,000 km!

2.   A chess board has 64 squares.  Place
      1 grain of rice on the first square,  (Total grains = 1)
      2 grains of rice on the second square, (Total grains = 3)
      4 grains of rice on the third sqaure, (Total grains = 7)
      8 grains of rice on the 4th square,   (Total grains = 15) 
      16 grains of rice on the 5th square and so on...

      Continue doubling the number of grains on the next square  
      Fill up to the 64th square on the board.
      How much rice will you need to fill up the board?
      You will need 400 billion tonnes of rice to fill up the board!
       This is about 1000 times annual global rice production. 

UNBELIEVABLE - Of course one hits reality limits before you can finish.  You cannot fold a piece of paper so many times and there is not enough rice to fill the whole board. 
These are examples of Exponential Growth.

There are a few important observations one makes here:

1.  Size of each step is double the size of the previous step
2.  Amount added in a step is greater than the total amount added in all the previous steps by one unit 

Let us now consider an example where time is involved:
Look at the next blog for this ...



Sunday, 12 August 2012

Critical Thresholds in Earth's Ecosystem...

Feedbacks, Tipping Points, Planetary Boundaries, Ecological Footprint, Irreversible Changes, Ecosystem Collapse are mentioned frequently. 
Lot of these are matters of opinion and the time scales associated with such predictions are important.  
When will we reach a tipping point and how long after that the ecosystem will change in a way never to return to the current state are relevant questions.  How long is 'never'?
In planning and making decisions, human time scales range from a decade to a millenium. 
Politicians and policy makers largely work on a timescale determined by the next general election - and that is most unfortunate in the present context.

In relation to the Earth's Ecosystem, Tipping points or Critical Thresholds are real.  They have occurred in the past.  Great extinctions have happened when the world's living species have been reduced to a small fraction of their pre-event numbers.  Even as recently as 12,000 years ago, global temperatures had risen by a massive 5 or 6 degrees in a matter of decades making a transition from the ice age to the warmer interglacial that we enjoy just now.

As human population grows, the rate at which we consume Earth resources and produce waste increases.  Ecosystem services (worth a cool $33 Trillion) have limits.  Earth can produce services we demad and clean up the waste we produce only up to an extent.  We are already using resources of the earth 50% faster than they may be replenished.
There are signs that Earth's capacity is being adversely affected by our overuse and may be weakening.  Increasing consumption will only quicken the weakening setting up a spiral towards collapse.  One can see how a tipping point may be reached if business as usual (increasing population and overconsumption) continues.

Scientists in Journal Nature (2009) have identified nine processes in the ecosystem which have critical thresholds or tipping points (subject to limits or planetary boundaries).  According to the study, three of these processes have already passed the tipping points with the others under serious stress.  Remember, however, it is difficult to identify the actual point when a prcess passes its critical threshold or even to know what the critical threshold is.
National Economic Council Report (January 2010) discusses these processes in deatil.  
At this stage we shall only list them.

1.  Climate Change
2.  Rate of biodiversity loss (terrestrial and marine)
3.  Interference with the nitrogen and phosphorus cycle
4.  Stratospheric ozone dpeletion
5.  Ocean acidification
6.  Global freshwater use
7.  Change of land use
8.  Chemical Pollution
9.  Atmospheric aerosol loading

We shall look at some of these in future blogs.

Saturday, 11 August 2012

Nature Services - a Cool $33 Trillion Worth!

The 1997 study of the value of services that Nature or the Ecosystem provides us was estimated to be worth a minimum of $33,000 billion!  Global GNP was $18,000 billion then. 
The estimates only included renewable ecosystem services, excluding non-renewable fuels & minerals, and the atmosphere.

What are we talking about? 

One way to think about it is to calculate what it would cost to replace the goods and services that nature provides us.  In fact, zero natural capital implies zero human welfare - it is not possible to totally substitute ecosystem services.  Their value is infinite.   

Again, what are we talking about?  Let me give some examples:

Pollination of crops by bees is required for 15-30% of US food production. 

In the drainage basin of Yangtze River, the annual economic benefits of maintaining forests for flood control and power services are estimated to be 3 times than harvesting them once for timber.  China now pays loggers not to cut trees but plant new ones.

Nature provides, we think free of charge, sea food, crops, fresh water, energy (hydro, biomass fuels), climate regulation, waste decomposition, pest and disease control, purification of water and air, nutrient dispersion and cycling... etc.  The list goes on and on.

So, what is the problem?  Why are we talking about it now?

The problem is that most of our decision making does not take into account the effect of our decisions on the health of the ecosystem services.  It seems to have mattered little in the past when the population and pressures on the ecosystem were small, but now the stresses created by humans are such that unless we start to give proper consideration to restoring the health and wellbeing of the ecosystem in our decision making processes then future human welfare may suffer in a big way.

In a proper market, ecosystem services must be valued and paid for.  The price of goods that use ecosystem services directly or indirectly would then be much greater.  For example, the true cost of burning oil, including repair to the environment, is calculated to be about $15 per gallon but in USA they pay $4 per gallon.  Cheap Energy has caused serious damage to the ecosystem.

Some parts of the ecosystem have already passed critical thresholds or tipping points and others may do so in future.  This will impact adversely on human welfare - already it is reckoned that since 1970, even though global GNP has gone up, human welfare index has not.

We shall look at the ecosystem stresses annd what we can do about it in the next blog.

Friday, 10 August 2012

Stability, Feedback and Tipping Points - (Part 3)

These days, Tipping Point is frequently used in discussions to describe a point of no return or a point of sudden and large change.
The change may be undesirable, catastrophic, unpleasant, unplanned, unexpected or irreversible.
Alternately the change may be sought for, as in marketing a product, or in social media to generate a lot of contacts. 

Stable systems return to their normal state of stability after they are  disturbed slightly by an external agent;  Remember the example of a marble in a bowl  Negative Feedback

However, if the marble is pushed more and more until it reaches the top of the bowl,  then a slight further push will take it to a new state from where it can not return to the original state.
The marble has passed the tipping point.  Beyond the tipping point, there may be a new state of stability, as shown in the diagram, or there may be a precipice, cliff edge – a point implying catastrophe.

Small changes can build up to bring a system to a state (tipping point) that even a further small change can cause large and irreversible shift in the state of the system. 

The pressures that human activities are placing on the Earth's ecosystem are increasing and we may be reaching a tipping point when serious undesirable and damaging changes to the ecosystem become inevitable. 
Earth is rapidly approaching a tipping point
Ecosystem collapse?

When the tipping point happens is difficult to predict.  In a complex system with many parameters it is not possible to exactly say when the system will switch to a new stable state or collapse.  One looks for signs of stress and forms an opinion about the future behaviour of the system.

A good read is Malcolm Gladwell's book in which he describes The Tipping Point as that magic moment when an idea, trend, or social behaviour crosses a threshold, tips, and spreads like wildfire. Just as a single sick person can start an epidemic of the flu, so too can a small but precisely targeted push cause a fashion trend, the popularity of a new product, or a drop in the crime rate.  He describes several examples such as a New Yorker district which becomes more and more dangerous because of small changes such as broken windows which convey the message to people that the neighborhood became less caring.

Wednesday, 1 August 2012

Stability, Feedback and Tipping Points - (Part 2)

In positive feedback, a change in one parameter causes other changes which then amplify the magnitude of the original change.

Example:  Arctic Ice Loss.  Global temperatures have risen but temperatures in the Arctic have increased much more rapidly over the past century.  This has resulted in melting of the ice cover in the Arctic circle.

Change (increase) in the one of the climate parameters (temperature) has caused change of a second parameter ( area covered by ice in the Arctic).

Ice is highly reflective.  Fresh snow sends back about 80% of Sun's energy falling on it, while ice is ~50% reflective. 
Melting converts the ice to darker water that reflects less than 10 percent of solar energy and absorbs the rest.
Greater absorption of solar energy increases the temperature which then causes more ice to melt...
A positive feedback cycle operates...

Another example of positive feedback is thawing of the permafrost - frozen earth in Siberia, Alaska and Canada. 

Positive feedback causes a drift away from the original stable situation. 
The drift may continue and become uncontrollable. 
Alernately, due to changes happening, other internal mechanisms of the system may come in and pull it back towards stability.
If the drift due to positive feedback continues then we can reach a tipping point - we shall discuss this in Part 3

World's Wittiest Best Quotes...

It is amazing how some people can say so much in a few words...

We are living in a world today where lemonade is made from artificial flavours and furniture polish is made from real lemons          ALFRED E. NEWMAN

People are more violently opposed to fur than leather because it's safer to harass rich women than motorcycle gang               JOHN VARLE
We have two ears and one mouth, so that we can listen twice as much as we  speak                 EPICTETUS (c 55-135 AD)
A celebrity is a person who works hard all his life to become known, then wears dark glasses to avoid being recognised                        FRED ALLEN
"We live longer,  but we think shorter.”       MARY CATHERINE BATESON
If you wanted to make an apple pie from scratch, you first had to create the universe              CARL SAGAN
No diet will remove all the fat from your body because the brain is entirely fat. Without a brain, you might look good, but all you could do is run for public office                       GEORGE BERNARD SHAW
Interesting people are nonconformists, swimming tirelessly against the flow of the cultural norm. Only dead fish go with the current.          ROY WILLIAMS
One camel does not make fun of another camel's hump.                   GHANAIAN PROVERB
If things are clear then they will have sharp edges  ANONYMOUS 
My grandfather once told me that there are two kinds of people: Those who do the work and those who take the credit.  He told me to try to be in the first group; there was less competition there.          INDIRA GANDHI
A lot of the people who keep a gun at home for safety are the same ones who refuse to wear a seat belt.                 GEORGE CARLIN
If dandelions were hard to grow, they would be most welcome on any lawn.        ANDREW MASON
How is it that we remember the least triviality that happens to us, and yet not remember how often we have recounted it to the same person.                         DUC DE LA ROCHEFOUCAULD
Why inflict pain on oneself, when so many others are ready to save us the trouble?                GEORGE PACAUD (1879-1937)
Ever notice that 'what the hell' is always the right decision?                 MARILYN MONROE (1926-62)
Quality is never an accident; it is always the result of intelligent effort.          JOHN RUSKIN (1819-1900)
The greatest pleasure I know is to do a good action by stealth, and to have it found out by accident.  
 CHARLES LAMB (1775-1834)
The average man, who does not know what to do with his life, wants another one that will last forever.                               ANATOLE FRANCE (1844-1924)
Often when I pray, I wonder if I am not posting letters to a non-existent address.          CS LEWIS (1898-1963)
Like airplanes, we all leave behind a vapour trail. And though we can easily see others’, we rarely see our own.     RP SIEGEL
If you think you are too small to make a difference, try sleeping in a closed room with a mosquito.             AFRICAN PROVERB
Some cause happiness wherever they go; others, whenever they go.
Everything we hear is an opinion, not a fact.  Everything we see is a perspective, not the truth.   MARCUS AURELIUS (121-180 AD)
The best way to predict the future is to invent it         ALAN KAY
One who is proud of ancestry is like a turnip; there is nothing good of him but that which is underground.   
AMUEL BUTLER (1835-1902)
If you have an apple and I have an apple and we exchange these apples then you and I will still each have one apple. But if you have an idea and I have an idea and we exchange these ideas, then each of us will have two ideas.      GEORGE BERNARD SHAW (1856-1950)
"Because almost everything -- all external expectations, all pride, all fear of embarrassment or failure -- these things just fall away in the face of death, leaving only what is truly important." "Remembering that you are going to die is the best way I know to avoid the trap of thinking you have something to lose. You are already naked. There is no reason not to follow your heart."                 STEVE JOBS (1955-2011)
We are here on Earth to do good to others. What the others are here for, I don't know.        WH AUDEN (1907-73)
Ideas are more powerful than guns. We would not let our enemies have guns, why should we let them have ideas?                   JOSEPH STALIN (1879-1953)
Don't be afraid to go out on a limb. That's where the fruit is.            H JACKSON BROWNE
They say such nice things about people at their funerals that it makes me sad that I'm going to miss mine by just a few days. GARRISON KEILLOR
“Forget Jesus, the stars died so you could be born.” LAWRENCE KRAUSS
“There are thousands and thousands of people out there leading lives of quiet, screaming desperation, where they work long, hard hours at jobs they hate to enable them to buy things they don’t need to impress people they don’t like.” — NIGEL MARSH

All truth passes through three stages.
First, it is ridiculed.
Second, it is violently opposed.
Third, it is accepted as being self-evident                             ARTHUR SCHOPENHAUER

  • Whenever a friend succeeds, a little something in me dies.
  • Never have children, only grandchildren.
  • A good deed never goes unpunished.
  • It's not enough to succeed. Others must fail                                                                                GORE VIDAL(1926 -2012)

Friday, 27 July 2012

Stability, Feedback and Tipping Points (Part 1)...

Be it climate change, economic situation, politics, society, relationships - we hear a lot about stability, equilibrium, feedback and these days the term tipping point is used frequently.

We, the homo sapiens,  are comfortable when things are going as expected and we can predict what is going to happen, at least, in the near future.  It just makes planning easier, there is more time do other interesting things - a state of equilibrium (stability) is sought.

Stability is defined as a state in which a system tends to return to its original state after being disturbed. 
A good example of such stable equilibrium is a bowl with a marble in it. If we disturb the marble by moving it up the side of the bowl and let go then after a few oscillations, the marble returns to its original position of stability.

If the bowl was upside down and the marble balanced at the top of the bowl then a disturbance in its position will lead it to fall off, never to terun to its original postion.  That is unstable equilibrium.

The question is what gives rise to stability? - why should a system return to its original position when disturbed? 
It does so because a disturbance causes the system to generate some sort of restoring force which operates to cancel the direction of change.
Gravitational forces pull the marble back towards it original position.  However, the marble oscillates for a while before settling down. 

When you disturb something, you need to do work which is stored in the system as energy (potential energy or I shall call it latent or hidden energy) which has to be eliminated before stability is regained.  This is achieved by dissipative forces or friction in the system. 
Friction converts energy to heat - kind of wasted energy.

For the marble, the new displaced position gave it a higher potential energy.  Oscillations about the lowest point in the bowl, cause loss of energy due to friction and gradually the marble returns to stability.  If the bowl and the marble were completely smooth with no friction present then the marble will oscillate for ever.

We have described above, what in physics is called
negative feedback in which stability is regained after the system has been disturbed.

A familiar example of negative feedback at work is the thermostat of your central heating system.  You set a temperature and the boiler comes on to heat the room to this temperature.  But the boiler doesn't cut-off at the exact temperature chosen on the thermostat.  If it did so, then as soon as the temperature drops by the smallest amount the boiler will have to come back on again.  What the actual systems do is to have a small acceptable range of say about 0.5 degrees on either side of the thermostat setting. The boiler heats the room to the setting plus 0.5 degrees and cuts off and only comes back on when the temperature in the room falls to the setting minus 0.5 degrees.
Refrigerators, ovens, fan heaters, air conditioning systems all work on this basis.  These are examples of what we call Linear Control Systems.  Wiki has a diagram to explain how they work

Global climate regulates itself through feedback mechanisms.
Economic activity, our personal relationships all seem to operate on the basis of feedbacks and responses. 

File:Ideal feedback model.svg

In part 2, we shall look at Positive Feedback...

Sunday, 22 July 2012

How much heat is given off by a human...

(An updated version of this post is available here).  Application to hypo- and hyper- thermia are also discussed there.

Heat is generated in biochemical reactions in cells. Each gram of carbohydrate generates 4 Calories, while fat and protein generate 9 and 4.5 Calories respectively.
Humans are hot-blooded and their body temperature is maintained constant at about 37C, the heat produced in the body has to be given off to the outside. This is done through breathing, sweating and radiating away heat energy to cooler surroundings, say at 20C.

Your calorie consumption goes up if you are physically active, like running or climbing stairs than when you are sitting calmly. In one hour, a 70 kg man would burn, approximately, 80 Calories sitting; 110 standing; 320 walking and 500 jogging.

Suppose, that every day a human consumes 2000 Calories (Some eat much more and get obese!).
We can calculate, using physics, the amount of energy produced in a day.
The Calorie used by nutritionists is actually equal to 1000 times the calorie used by physicist to measure energy. Note C and c in the two definitions of energy.

1 Calorie = 1000 calories or 1 kcal

In physics the usual unit to express energy is a Joule (J), and 1 calorie = 4.18 J

So we consume 2000 x 1000 calories/day
= 2,000,000 calories/day
= 2,000,000 x 4.18 J/day
= 8,360,000 J/day

To make sense of Joule per day, it is better to talk about power that is J per second or Watt (W)

A day has 24 x 3600 second = 86,400 seconds

We produce 8360000/86400 J per second (W) = 96.76 W (nearly 100 W) and this is given off to the surroundings as heat.

A human gives off heat equal to that of a 100 W incandescent light bulb (old style light bulbs) which actually converts most of the electricity to heat.
The new fluorescent light bulbs and particularly LED lights are more efficient in converting electric energy to light and that is why they do not get too hot when in use.
They are also cheaper to use.

Now you know why the room feels very warm when a lot of people are present and talking animatedly.
Or why you sweat and breath faster when jogging - you are burning extra Calories and producing heat faster.  The body has to get rid of the extra heat by sweating and respiration.

Thursday, 19 July 2012

Energy has been too cheap...

There are over 7 billions of us in the world today and we are living very well thanks to the available cheap energy. 
How under priced is the energy?
About a factor of 500 relative to manual labour - this is how it works out...

A gallon of petrol costs £6 in the UK (about £3 in the USA!) and provides energy equivalent to 500 hours of human labour worth £4000.
The amount of work that oil performs for you is equivalent to having hundreds of slaves working round the clock.
Thanks to cheap oil, even the kings did not have the comfortable life style that an average middle class family now enjoys. 

It is one of Ravi's laws of nature that when something is cheap, it is bound to be misused
Coal, gas and oil are no different.  Humans have wasted energy as if it is unlimited, ignoring the damage to environment and climate.  Cheap energy has also fuelled overconsumption.

Did you know that only humans and their pets suffer from obesity?
Have you heard of a wild animal being fat?

Cheap energy has also prevented development of plentiful, unpolluting renewable energy like solar and wind. 

Global power consumption is 15,000 GW.
Solar power falling on the Earth is 120,000,000 GW!
This is 8000 times greater than what we consume. 

But, humans have failed to tap this unlimited source of energy because buried under ground they found a heap of fossil fuel that will do them for another 100 years or so. 
Never mind the damage - lot of it irreversible - that is being caused by the folly.

Some people are asking - is it too late?  Most do not care.
I do not know the answer but feel sure that soon it will be too late.

Enjoy the lifestyle while it lasts!

Tuesday, 17 July 2012

Science for All - A community Education Initiative

Science For All
An exciting and innovative series of science talks launched in East Kilbride in October 2006. The Science For All programme is the result of a partnership between University of Glasgow & Scottish Enterprise in Lanarkshire.
The creator and presenter Dr. Ravi Singhal specifically designed the community based programme to highlight the role science plays in everyday life and improve the understanding of science in today's modern world in an engaging and informative way.
No previous knowledge of science is required and everyone is welcome to attend. The talks are most suitable for secondary pupils and adults of any age.
'The talks will be entertaining as well as being informative and thought-provoking for all attending. We are hoping to attract as many people as possible to the talks and guarantee there will be something for everyone, from the beginner to the expert.'
Audience comments include 'his lectures are so well prepared and well illustrated...his presentation is suitable for an audience with even quite limited previous knowledge of physics or cosmology, but also for enthusiasts.
Programme Details
All talks are free of charge and will take place from 11am on Saturday mornings in the James Watt Auditorium, East Kilbride Technology Park, G75 0QD. Click for map
To find out more email   ektalks@yahoo.co.uk    more information.
  • Meeting Maxwell:  29 April 2014 Parton                                                  (D&G Science Festival)
  • The Curie Family and the Story of Radioactivity:                                    24 January 2014
  • Energy from Thorium: 25 January 2013
  • Sustainability: October 2012 (five 90 minutes                                                               meeting)
  • Sustainable development: October 2012  
  • Population growth & sustainability: September                                                                   2012
·         Talks 60 to 64  Population: Elephant in the Room (To be scheduled)
·         Talk 59 Renewable Energy Sources  Glasgow Science Festival                      10 June 2012 (120 Minutes)  
·         Talk 58 Climate Change and Oceans  Glasgow Science Festival                     9 June 2012 (120 Minutes)
·         Talk 57 Climate Change Dumfries Science Festival                                         10 May 2012 (120 Minutes)
  • Talks 52 to 56: Nanotechnology                                                                      3, 10, 17, 24, 31 October 2011 (90 minute talks)
  • Talks 46 to 51: Einstein and the Theory of Relativity:23, 30 October and 6, 13, 20 & 27 November 2010
  • Talks 41 to 45: Exploring the Cosmos:30 January and 6,13, 20 & 27 February 2010
  • Great Scottish Inventors: to be rescheduled
  • Talks 35 to 40:
    Climate Change: 3,10,17 & 24 February and 3 & 10 March 2009
  • Talks 30 to 34:
    Science in Medicine: 1, 8, 15, 22 & 29 November 2008
  • Talks 25 to 29:
    Atomic Nucleus and Nuclear Energy:                                                           16, 23 February and 1,8 & 15 March 2008
  • Talks 15 to 24:
    Micro- and Nano- technologies: 20, 27 October, 3, 10, 17 & 24 November 2007
  • Talks 13 and 14:
    Alternative Energy Sources: 14- 21 April 2007
  • Talks 8 to 12:
    Global Warming and Climate Change: 3-31 March 2007
  • Talks 1 to 7:
    Exploring the Cosmos: 28 Oct - 9 Dec 2006
In 2010 and 2011, three eight-hour sessions were held in the Department of Life Long Learning at Strathclyde University, Scotland.  The topics were Exploring the Cosmos, Nanotechnology and Einstein & the Theory of Relativity. 
Speaker Profile
Dr Ravi Singhal has lived in East Kilbride since 1970 and recently retired from Glasgow University's Department of Physics & Astronomy after 36 years. During that time he taught students from a wide range of disciplines and covered topics as diverse as birth of the universe to quantum mechanics. Dr Singhal is a widely published academic with almost 200 research papers, reviews and book chapters related to lasers, environmental and nuclear physics.
A passion for science and education combined with a desire to 'give something back' to the community Dr Singhal found retirement gave him the perfect opportunity to start up the Science Talks programme:
'My talks are designed to improve the awareness and importance of science at a local level and highlight the role it plays in everyday life...volunteers who will be able to expand the programme and give different talks to the community on diverse subjects including medicine, the environment, alternative energy sources and nanotechnology.'

Population: Elephant in the Room

Population – Elephant in the Room

We have only one planet and its resources are limited. Global population quadrupled during the 20th century.
Such is the dynamics of exponential growth that even if the population increases half as fast (doubles in 100 years), in about 1300 years each of us will only have a patch of 5ft x 5ft on dry land with no room for plants, animals or anything else.  Overcrowding will be felt much before that.  In fact mother Earth might get fed up at some stage and do something about her childrens' behaviour.

Consumption and the number of domesticated animals increases in line with population growth. We are depleting non-renewable resources and polluting the environment at a rate that the Earth cannot cope with.
Just now we are using resources 1.5 times faster than the Earth can regenerate. If everybody consumes as much as the Americans do, then we require resources of fifteen Earths.

Our planet responds to the stresses we create.
Bio-diversity is diminished.
Global climate is impacted by the burning of fossil fuels.
Oceans, where 60% of all photosynthesis happens, become polluted, more acidic and less able to sustain aquatic life.
Overgrazing is a major cause of desertification, irreversible loss of topsoil with consequent impact on the fertility of agricultural land.
Aquifer depletion due to over-pumping & retreat of mountain glaciers in response to rising temperatures create serious concerns about future fresh water supplies for human use and for agriculture.
Higher global temperatures are causing sea levels to rise, threatening many highly populated coastal areas.
Some of the above global parameters have already passed the tipping point and further changes can happen uncontrolled, quickly and irreversibly.

Various estimates put the carrying capacity of the Earth from 500 million (at US level of consumption) to 10 billion (at an unacceptably low level of consumption).
Nobody wants to talk about managing population growth.
Population is an elephant in the room.  It has been more convenient to ignore the problem.
The fundamental issue is the growth in population and that must be addressed urgently.  Education, empowerment of women, birth control can make a difference.

We have to ensure that the carrying capacity of the Earth is not further damaged by our excessive consumption habits.
Energy has been too cheap, at least four times cheaper than its true cost and must be priced correctly. A rapid transition from non-renewable fossil fuels to the plentiful supply of renewable solar and wind energy is essential to manage our climate and pollution.
There is enormous potential for efficiency gains by innovative designs and good practices.
For example, plug-in hybrid cars can potentially solve the storage problems for electricity, reducing the need to provide extra power generation capacity at peak demand times.
Smart grids and smart metering will go some way in alleviating the peak load problems. Regenerating our forests will help in stabilising the climate.
Food and water security can be helped by consuming more plant proteins in preference to animal protein which is up to ten times more water and energy intensive. Demand for animal protein is rapidly increasing in the BRIC countries and others.
Bio-fuels are joker in the pack.

It may not be too late to act, but the geo-political situation does not inspire confidence.
Nano- and digital- technologies will help to alleviate many of the problems but only if the population stabilises. The US population is projected to increase by one hundred million by 2050. Imagine the extra resources required to accommodate such numbers at the current US consumption levels. Over 2500 million people in China and India would like to consume four times more than they do now!

There are those who talk about space colonisation and people living on asteroids etc.
Technologically it might be possible sometime in the future but the question one needs to ask is: “What are the 7 billion humans on the Earth for? Why are they here?”
Surely human race is not here just to increase their numbers but consideration has to be given for the quality and fulfilment of life.

We have the choice of managing the population and what we consume and saving our civilisation by acting now, or let nature do it in her own way – that will not be pleasant for sure.
What do I tell my daughter when she asks “What type of world shall I inherit, daddy?”

ScienceforAll, a Community Education Initiative, will look at the issues and their potential solutions in a series of six 90-minute talks this autumn. Further announcements about the free talks will be made at the end of August 2012.                                                        ... Ravi Singhal (17/07/2012)