Black Friday Sale

New black hole discovered in New Zealand toilet

After bringing the world news of the Black Hole Lane near a reader's home in Hereford, UK, last month, Feedback is delighted to learn of the existence of the Black Hole Public Toilet in Nelson, New Zealand

By Marc Abrahams

22 November 2023

New Scientist Default Image

Josie Ford

Black hole bum

Roger Sharp adds another item to Feedback’s compendium of black holes that are findable on surface maps of our own planet (7 October). Visitors to the Maitai Esplanade Reserve in Nelson, New Zealand, may find relief upon entering the Black Hole Public Toilet.

Feedback notes that siting a toilet in an astrophysical black hole would eliminate the need for some pricey aspects of modern waste-disposal facilities: specifically a sewage-piping system or a septic tank.

Needling the patient

How far is it probably OK to insert a needle a little too far into a person’s abdomen? Surgeons – 365 of them, in 58 European countries – expressed their opinions about that. Their thoughts, their desires, perhaps even their dreams are distilled in a study called “The relevance of reducing Veress needle overshooting“, by researchers in the Netherlands and Malta.

These are needles used to inflate a patient before doing the look-around-inside and then the cut-and-manipulate activities that are the highlights of most laparoscopic surgery. The specific kind called a Veress needle has long been a standard gizmo to stick-and-insufflate a body who is in the shop for repairs. It serves roughly the same function as the simpler kind of needle used to inflate footballs.

The study probes the desire or need for some new, better design for Veress needles.

The researchers say that the surgeons feel “that it is important to facilitate a good grip on the needle shaft, as most of the respondents hold the needle instead of the grip. The reason is that the grip is located too far from the abdominal wall as some surgeons attempt to stabilise their hand by touching the abdominal wall with their fingers during insertion. The data also indicates that the maximum overshoot should be limited to 0–10 mm.”

Nearly every professional activity has a characteristic tolerance for error. With the publication of this paper, the public can become more aware of the professionals’ general tolerance for laparoscopic surgery patient insufflation-needle over-insertion.

Gangue in goaf

Unfamiliar scientific terminology can be a treat – especially when the words are dredged up from depths unfamiliar to most people.

So it is with gangue and goaf. Feedback encountered them while reading a report by Zhanshan Shi and colleagues at Liaoning Technical University, China, called “Simulation test study on filling flow law of gangue slurry in goaf“.

Goaf is the waste material that accumulated while a mine was being mined. Gangue is the apparently worthless portion of the ore taken from a mine. Inevitably, there is gangue in goaf.

There is also mystery. The report says “there are few studies on the flow rule of gangue slurry in the accumulated rock mass of goaf”.

The report is a reminder that there is always something, be it only information, yet to be mined.

Plank on wood

In the vast nominative determinism forest of people whose names are cheerily, almost eerily related to their work, some trees – that is, some people’s names – are especially fit to purpose. One is Marlin E. Plank, who was a research forest products technologist at the Pacific Northwest Research Station in Portland, Oregon. He spent much of his professional life estimating how much commercially useful wood can be obtained from this or that kind of tree.

Stewart Harrison tells Feedback of his joy upon discovering Plank’s 1982 paper called “Lumber recovery from ponderosa pine in western Montana“.

A journey through the library turned up further Plankitude, including Plank on logs: “Estimating cubic volume of small diameter tree-length logs from ponderosa and lodgepole pine“.

Plank’s most refined log paper may be the one he co-wrote with Floyd Johnson in 1975 called “An empirical log rule for Douglas-fir in western Oregon and western Washington“. It tells of a better way – a way unglamorously, woodenly practical – to estimate how much wood the woods would yield if the trees were harvested à la Plank.

Plank and Johnson said: “The traditional procedure for estimating lumber tally volume is based on theoretical log rules, defect deductions, and overrun factors. This procedure is indirect, subjective, and complicated. It is also apparently inaccurate. A better procedure, one based on actual rather than theoretical lumber recoveries, is described.”

Plank died in 2014. A Plank remembrance website says: “To plant trees in memory, please visit the Sympathy Store“.

Eye spy countermeasure

Greg Rubin looks askance at fellow computer security professionals who warn that video screen info can be plucked from reflections on video chatters’ eyeglasses (28 October).

He says: “This is something my community has known about for years. Sometimes we’ll even comment on the reflections we can see during video calls. Personally, I recommend using a simple defence strategy during long and boring conference calls. Just close your eyes and take a nap.”

Marc Abrahams created the Ig Nobel Prize ceremony and co-founded the magazine Annals of Improbable Research. Earlier, he worked on unusual ways to use computers. His website is

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