Anyone who has done a PhD knows that you go through an educational phase transition. You are no longer instructed by others, but instead teach yourself. You cease acquiring basics and begin assimilating values and behaviours that allow you to participate in the scientific way of life. It is an apprenticeship that cannot be condensed into a set of rules.

Survivors of graduate education, however, come to appreciate the fact that certain valuable maxims distil much wisdom. I don’t mean vague injunctions like “persevere”, “adapt” or “network”; they are good and true but possess all the functionality of your horoscope. Nor do I mean the practical advice on shelter, food and companionship (“choose a romantic partner who knows PowerPoint”) that is generic to graduate life. What I mean are useful maxims for the blossoming physicist. Let me illustrate.

Never means three months

I once learned an important lesson from Andrew Kevey, who used to be chief spectrometer engineer at the High Flux Beam Reactor (HFBR) at the Brookhaven National Laboratory in the US. While learning the ropes at the lab’s previous neutron source – the Graphite Research Reactor – Kevey’s advisor had told him to design and build a small calibrated turntable on which to mount crystals for a spectrometer. Kevey asked how much load it would have to bear. A few ounces, came the reply – never more than a pound.

Three months later, the advisor – whose research programme now involved magnetic properties – handed Kevey a 50 pound magnet and asked him to install it on the turntable. Kevey protested, citing the advisor’s earlier remarks about the load.

“You idiot,” the advisor exploded, “don’t you know that, in physics, never means three months?”

This important maxim, Kevey explained to me, is a condensed way of saying be prepared for rapidly changing demands and revised expectations.

Build in the centre of the room

Brookhaven physicist Laurence Passell discovered a related lesson while a graduate student at Berkeley. His advisor, who was conducting experiments in low-temperature physics, had instructed Passell to prepare an experiment in a new basement laboratory. When Passell first walked into the still-empty lab and began to set up, he ran into a more experienced graduate student who cast a disdainful eye on Passell’s first efforts. “Let me give you a piece of advice,” the student said. “Always start building your experiment in the centre of the room.”

“I laughed at the time,” Passell recalls, “but the advice was extremely useful.” For doing physics, he explains, means embarking on a random walk. Regardless of the direction in which you set out, you rarely know where you will end up. And experimental divagations expand radially. So lesson two is: give yourself as much space as possible.

Don’t make it better than necessary

Passell learned another important lesson at Berkeley: don’t make your equipment better than it needs to be. “The best piece of scientific apparatus is one that falls apart the day after you finish using it,” he explains. Violation of this principle cost Passell a research programme at the HFBR in the late 1960s. He was planning to use a new neutron spectrometer that was being built by a perfectionist retired navy officer who was aiming to build the best of its kind in the world. But as Passell recalls, the officer never asked himself “Is it good enough?”. Instead, he asked “Is it as good as I can make it?”.

“The answer, of course, was always no,” says Passell.

At one key juncture, for instance, the officer became dissatisfied with the crude but effective shielding method that had to be realigned each time the beam direction was shifted. As the spectrometer drum turned to change the angle of the neutron beam, a series of wedges would lift up out of the way of the beam before dropping back down on the other side. Unhappy with this rudimentary design, the officer instead began installing an elegant system in which a rotating cone block inside the drum automatically realigned all the shielding.

Passell looked on, horrified, as the device tore up the spectrometer’s budget and wrecked its construction schedule. His research programme was soon terminated.

“An experiment is perfect when the equipment is just good enough,” he concluded.

Over-extend yourself

A fourth key maxim that I have often heard scientists mention is: if you really know what you are doing, you should not be doing it. For if you know that much, someone else has probably already done – or is about to do – what you are intending. Your results, in other words, will soon be obsolete. As Fermilab’s former director Robert Wilson liked to say, “Something that works right away is over-designed, and consequently will have taken too long to build and will have cost too much.” Doing science effectively and efficiently requires you to over-extend yourself to the point where some things will not go as planned.

This principle is, of course, a secret. You won’t find it in textbooks, nor will you hear science administrators publicly endorse it. Their job is to know it and cover it up.

The critical point

Shacheenatha Jha, a physicist from Case Western Reserve University, liked to tell his graduate students that “When you start telling me what you want to do, instead of me telling you what I want you to do, you are ready to graduate.” Acquiring the requisite autonomy to do that cannot be captured in a finite set of rules.

Nevertheless, every scientist who has successfully endured the process learns a set of maxims for effective action. These ought to be compiled and passed on for the benefit of future generations. I therefore invite you to send me the most important one you learned in the course of your PhD training or other learning period, along with an example. I shall discuss your comments in a future column.

• What is the most important thing you learned in graduate school? Send your advice to Robert P Crease at the address given below, or by fax to +1 631 632 7522, or by e-mail rcrease@notes.cc.sunysb.edu