These were known as “Roman candles”.Most nuclear weapons are designed to burst high above their target, so that terrain features cannot shield their victims from blast and heat. Then, a rising column of hot air sucks up irradiated dirt from the ground, which returns to earth as fallout. These tests showed that a one-kiloton bomb had to be buried 250 feet deep to contain the blast. In tests, it has never penetrated more than 20 feet of earth.Robert Nelson, a nuclear-weapons expert at Princeton University, says there is no novel technology around the corner that will bring an impressive leap in penetration. “The rules of long-rod penetration say a steel rod hitting concrete can penetrate about 10 times its own length. But even that would require an impact velocity liable to melt the casing or destroy the warhead.”Supposing scientists can burrow twice as deep as their best efforts to date, their bomb will detonate 50 feet underground. Proponents of the RNEP talk of attacking bunkers as deep as 1,000 feet.

A bomb that could shatter a bunker 950 feet below it without broaching the ground 50 feet above would be a wonder weapon indeed.In the 1960s, the US government carried out a series of tests known as Operation Plowshare, to study the feasibility of using nuclear weapons to build substitute harbours and canals if war or catastrophe destroyed existing facilities. At the depths attainable by a ground-penetrating bomb, said Professor Sidney Drell, the director of the Stanford Linear Accelerator, not even the smallest nuclear explosion could be contained underground America has an earth-penetrating nuclear bomb, the B61-11. In the public debate, these have been conflated into a single weapon, able to destroy buried dictators without collateral damage. In fact, there is no such device.
When Congressional supporters of the nuclear bunker-buster enthused about a bomb that could be safely dropped on a bunker in the middle of a city without harm to innocent people above ground, physicists reacted with scorn. The weapons that have grabbed most headlines are the RNEP and the mini-nuke. The Cold War – and the principle of mutually assured destruction – may be over, but research into nuclear weaponry continues apace.

The US, for example, is to study four new types, according to an agenda leaked from last month’s US Strategic Command meeting. These include an enhanced radiation (“neutron”) bomb; a bunker-buster, the Robust Nuclear Earth Penetrator (RNEP); a “mini-nuke” battlefield weapon with an explosive yield equivalent to 100 tons of TNT; and an “agent-defeat weapon” designed to incinerate anthrax spores or nerve gas. Child neglect is a major problem which has been severely neglected in all the ethical discussions, and it raises a real question as to whether everyone and anyone has the right to bear children.Lewis Wolpert is professor of biology as applied to medicine at University College, London. But will it really make more difference than currently exists between the rich and poor, the former giving their children all sorts of advantages? Emphasising the ethics of designer babies is a way of avoiding the very real problem that about one in 10 of all children suffers some sort of abuse, and thousands are registered as requiring special care because of their dangerous parents. Who, for example, is being harmed in all the recent fuss about choosing an embryo with the right genes to help a sibling? Both children will certainly be very well cared for. And it is care of the child that matters.There are fears that those who have designer babies – choosing children with particular genes that code for hair colour or height, perhaps – will be part of a superclass and increase the inequalities in our society.

This idea is a relatively recent one, with religious underpinning but with neither argument nor evidence. The Magisterium of the Catholic Church demands that the embryo be respected from the first instance. But what has to be considered in every case is the child and its future wellbeing, and not to do so is totally lacking in respect. What possible argument from ethics could be used against prenatal diagnosis of an embryo obtained by IVF, if the diagnosis prevents the implantation of embryos with defective genes? I know that some people object, but there is no evidence that the early embryo is a person.