Tony stated "Net overseas migration accounts for about 60 per cent of the country's population growth". In fact, it accounts for about 100 per cent. An extremely simplified example can explain the error.

Assume that this year (year 0) 10,000 young single adults migrate to Australia, form a community separate from the main Australian community, and marry to create 5000 couples. By year 10 they will have 10,000 children, and by year 40 they will have 10,000 grandchildren. By then, the increase to Australia's population stemming from the original migration will not be 10,000 but 30,000. Such activity has been occurring for years. Thus, this year the population growth due to net overseas migration will equal not just this year's net immigration, but also this year's births of descendants of people who migrated to Australia over the past two generations.

The population growth due to the rest of the Australian population (ie the real 'natural increase') is about zero. The term 'natural increase' is being used inappropriately in population statistics.

Because immigration rates have recently skyrocketed, future population growth due to past immigration is about to skyrocket. Even if immigration ceased today, Australia's population growth will be much higher than that of most comparable countries for another two generations. To avoid worsening population growth problems, immigration to Australia should almost cease until the population growth falls to about zero.

R. Salmond , Melba

Athol Morris (Letters, November 19), like John Howard, is horrified that another country – in this case Indonesia – would try to influence our foreign policy.

What exactly to they think diplomats are employed to do? No doubt, for consistency, they will also be calling for the removal of sanctions against Iran.

Morris is untiring in his attempts to influence Australia's foreign policy in what he perceives to be Israel's interests. Howard's most important foreign policy decision aptly led to his being described as a US deputy sheriff, a badge he wore with pride. Hypocrisy abounds.

John McMahon, Griffith

Scott Morrison's frat-boy attempt at titillation, in reply to Pamela Anderson's appeal to him over the government's ongoing abrogation of its duties towards the Australian citizen Julian Assange, tragically proves that the only hat that fits him is indeed the one branded Porky's, already of meat-pie-devouring fame.

Most prime ministers, upon public election, feel elevated to claim to "govern for all people". Evidently the unelected Morrison feels free to do as he pleases, play acting just for yobbos or — worse — assuming that's all Australians are.

Alex Mattea, Sydney, NSW

In the interests of reducing the amount of packaging used on new appliances, how difficult would it be to make the manufacturer responsible for the disposal of the packaging as well as the actual item when it ceases to function.

This could work well on electricals, as so many of them now have a short life. One year and one month after purchase the "built-in obsolescence" kicks in. It might encourage producers to market items that perhaps last longer, like they used to. With China no longer accepting our rubbish, why don't we step up our demands for better quality products?

Alayne Richardson, Narrabundah

As a chemistry scientist I wish to discuss the real as against the grossly misunderstood meaning of common terms in the food industry, such as organic food, and chemicals.

First, let it be known that calories weigh absolutely nil. They are energy, not mass units.

Per se, calories do not increase your weight!

Chemicals: By definition, virtually everything is a chemical.

There are organic chemicals, carbon-containing by definition.

Truly organic compounds, and mixtures of them, invariably involve chemical combinations with elements such as hydrogen, oxygen, sulphur and many others, and they abound in living systems. There can be no life here without carbon.

Our food is mostly the dead materials derived from living systems.

Thus the expressions organic food, and chemical free, are clearly meaningless from a chemist's perspective. But organic food has come to mean food derived from plants not treated with insecticides, or animals not subject to nasty fertilisers used on grasses and grazing soils.

On "low or fat free", one should be aware of cis and trans fats, the latter regarded as nasty; some argue the former can be as well, depending upon the degree of unsaturation.

On "no added sugar", or "sugar free", one should know that there are numerous and very different sugars, well more than 20.

For example, glucose and fructose, not healthy when in excess, are chemically quite different to table sugar (sucrose), but the latter slowly converts to the two others in vivo.

(As an interesting aside, lactulose, a disaccharide sugar like sucrose, is superb for constipation!)

Sugar content of foods labelled without "added sugar" is often very high, and the same is true of salt, nasty in excess, that is frequently found in a larger amounts in foods you would never expect, (e.g. ice cream).

Read labels carefully!

Greg Jackson, Kambah

Mario Stivala's letter justifying shoot-to-kill training was right in the instances he wrote about.

It was formalised by the FBI at the time of the Dillinger-type criminals.

The rule was that if you had to draw your gun, aim at the chest and kill the target.

In some cases it made good sense.

In Melbourne a decade ago a 15-year-old, high on drugs, who had fallen out with his girlfriend and wanted to end it all found a sunken area in a local park. He wandered back and forth in the area carrying two carving knives he had shoplifted from a supermarket.

The police arrived and negotiated and then called the dog squad.

The sergeant in charge lost patience and before the dog squad arrived ordered the other three officers to draw their weapons and arranged for all to shoot to kill at exactly the same time. Doing that no one officer could be held accountable for the killing.

The moral of the story is that what is understandable in some circumstances is bloody wrong in others.

Howard Carew, Isaacs

Scott Morrison attended the APEC Leaders Forum in Port Moresby hopelessly under-prepared. He apparently swallowed the line that a "significant push-back" to China's ambitions in the Pacific was a useful outcome of the meeting - but many people question that. I don't agree with all that China does, but I watched President Xi Jinping's address to APEC on the ABC and found it comprehensive and thought-provoking. The US-Australian-PNG response – a proposed revival of a naval base on Manus Island – scarcely compares. And the after-thought, to help PNG improve electricity supply, not only confirms the Chinese criticism that we've been under-investing there, but also begs the question of the Coalition's track-record in that field.

China is our biggest trading partner and, with an unpredictable administration in the US, we need agile politicians who can make decisions in our interest. There is an ominous sense we are being sucked into an unnecessary confrontation, and Morrison failed to counter it. If Pence was simply following instructions from Donald Trump, a very firm no would seem a better response than flat-footed complicity. Far more effective than any statements from China, it would have bought time to prepare a more measured APEC outcome and clearly signalled that Australia and PNG shouldn't be taken for granted as "allies" in any trade war the US tries to mount.

Brian Cooke, Waramanga

Albert White's criticism (Letters, November 20) of the narrowly framed economic benefits of household drone deliveries promoted in the study done for Wing is on the money.

Why do so many politicians automatically assume that money and the economy must be considered as more important than the community's quality of life? Bonython residents have already demonstrated in numbers that drone deliveries are a major attack on this front. People's well-being and health is being ignored in favour of dubiously constructed economic arguments.

Murray May, Cook

The saying used to be "What's good for the goose is good for the gander" although maybe this should be changed to 'What's good for the goose is good for the daughter' – basically everyone should be treated the same.

When Hillary Clinton used a private email server, Donald Trump said "If I win, I am going to instruct my attorney general to get a special prosecutor to look into your situation". This was seen in many circles to be a reasonable idea as her email usage was considered inappropriate. The situation has become more complex now as his daughter Ivanka Trump has sent hundreds of emails relating to government business from a non-government and potentially less secure email account. This is effectively the same as the situation that Hillary was attacked for. Bring on the equality of the legal system. Ivanka Trump should also face investigation.

Dennis Fitzgerald, Melbourne

John McKerral in his letter (Letters, November 20) claimed you cannot generate energy and supported coal fired power plants.

Firstly, during nuclear fission and fusion some residual matter is turned into energy according to e=mc squared. Albert Einstein seemed to believe that energy can be created. The World Coal Association has stated that the average efficiency of coal fired plants is 33 per cent, and 40 per cent at best.

They are also inflexible and take a very long time to start up. In contrast, a combined cycle gas turbine (CCGT) is 60 per cent efficient and can achieve full power in less than half an hour. CCGTs can also be used to complement variable power sources and are being installed around the world, including nuclear power rich France.

Of course, since the Australian government permits most of our gas to be exported, we cannot fully utilise the CCGT technology. We will just have to "chug along" with the "clunky" coal-fired plants.

John Simsons, Holt

Today's editorial ("PM's fix for congestion no solution", November 21, p14) calls for more attention to be paid to urban infrastructure, with which I agree wholeheartedly.

The editorial also mentions Christopher Pyne's view that this country could accommodate "many more than" its present population of about 25 million, a view with which I certainly do not agree.

This country, which has relatively little land capable of supporting human life, cannot cope with indefinite population growth, as Mr Pyne's comments imply.

Furthermore, as climate change – which the Morrison government chooses to ignore – progresses, the population-carrying capacity of Australia is bound to decrease rather than increase as required by Mr Pyne's policy.

Douglas Mackenzie, Deakin

Australia's latest Liberal Prime Minister says he has just discovered that the roads are clogged, the trains are full, and schools are taking no more enrolments – in Sydney and Melbourne, anyway. He blames this situation on the migrants, and says we have to slow down our intake.

Scott Morrison might like to shoot the blame home to where it belongs. When Peter Costello was treasurer, he smugly told the world he had a budget surplus so big that he didn't know what to do with it. Back then, not one road, train system or school could attract his attention. Costello did know about the numbers of migrants coming into the country at that time, and how many more were expected in the years leading up to now. He simply never thought that something should be done to make it ready for them. So he just gave all the money away.

And lest we forget: Liberal prime minister John Howard did nothing to stop Costello's nonsense. In fact, he encouraged it. Scott Morrison would do best to admit that a lack of planning by Liberals in the past is what has produced the problems of today.

Such a change from the usual Liberal smoke-screen would be so refreshing that a huge number of people could be surprised into voting Liberal next year.

G.T.W. Agnew, Coopers Plains

ISLAM TARNISHED

For any Muslim who understands their faith, incidents of terrorism cause great sorrow and despair. Tarnishing the name of Islam, which teaches peace, justice and safety for all individuals, regardless of faith, will not achieve anything. The acts of these individuals have nothing to do with Islam. Just like we shouldn't criticise other faiths for the indecent, inhumane acts of certain individuals, we can not blame Islam for the act of one individual. Our thoughts and prayers are with those impacted by the incident in Melbourne.

B Nasir, Toowoomba, Qld

LIFE'S CONSEQUENCES

We won't forgive, we won't forget, the mantra of the terrorist, after Australia's invasion of Iraq, based on American lies. Was Australia's invasion of Iraq a war crime?

Imagine some nation invading Australia for regime change, and using the excuse of looking for weapons of mass destruction.

Richard Ryan, Summerland Point, NSW

THOUGHT-PROVOKING

Bravo Dr Randa Abdel-Fattah for your thought-provoking article (The Canberra Times, November 18) offering your perspective on the terrorism debate following the recent Bourke Street attack. Having now only discovered your web page and publications list I must certainly read more of what you have written.

Jeff Hart, Kingston

KNOWING IT ALL

Nick Georgalis ("'Mr Geocon': Nick Georgalis on the property empire and Canberra's future", www.thecanberratimes.com.au, November 18) clearly thinks he knows what's best for Canberra (including, incidentally, advertising demeaning to women). What ordinary Canberrans want for our city is of no consequence.

Patricia Saunders, Chapman

FAIR GO ON FETE FINES

Whoever made the decision to target school fetes for revenue-raising parking fines is a disgusting individual. If the Labor government is so desperate for revenue then it should cancel stage two of light rail. We cannot afford it.

Phil Nicolls, Monash

HERE'S A CHALLENGE

It sounds like Matt Golding has given up on the Donald judging by his comment "Donald Trump tweeting overnight ... but with Trump it's getting harder and harder ... how do you make a clown look funny, how do you send up someone who seems to send himself up without trying ("Picture imperfect: cartoonists shine in eventful year", November 17, p16). Your challenge Matt, should you chose to accept it, is to come up with a Letters 'toon portraying Donald tweeting a response to your assessment of him!

Allan Gibson, Cherrybrook NSW

THIS IS A SURPRISE

The Hanson-Latham tandem has lasted longer than I expected.

M.F. Horton, Adelaide, SA

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