Hacker News Reader

Comment by alkonaut | Hacker News Reader

> two million cubic tonnes

The British really do have the weirdest units.

Cubic tonnes are technically a real and valid (SI even, ish) unit of measurement (for example the fundamental evaporation rate of a black hole via hawking radiation is on the order of 100 million cubic tonnes per second), but I think in this case they're just outright wrong.

What does cubic mass mean?

The time it takes a black hole to evaporate is proportional to the cube of its mass. If you graph mass-cubed versus time, it decreases linearly at about 100 million cubic tonnes per second. The actual mass decreases at a rate that's inversely proportional to the square of the mass.

Interestingly this may be a typo as the article mentions cubic meters. But wiki says cubic tons is a measure of volume that is obsolete in UK and mostly used in the US

It really irks me that journalists cannot make the slightest effort using proper units. Here I understand they meant 2Tm³ (terameter³).

Feel free to put in parenthesis the number of British buses or American football pitches, for the older folk from UK and USA if necessary.

But please use units that are universal and scientific!

No matter how you parse it, it cannot be 2Tm³. The most generous reading would be "two trillion cubic metres" rather than two million. It could also be read to mean that you want to cube a terametre.

If you're going to be pedantic, please put in more effort in identifying the correct unit of measurement, whether it's feet, meters, leagues, or terameters.

A terameter is a unit of length equal to 1 trillion meters.

A cubic terameter is 1x10^36 cubic meters.

2 million cubic meters would be something like: .000000000000000000000000000002 cubic terameters

Or: 2e-30 terameter³

If you're wanting minimalconversion, the amount comes to 2 cubic hectometers.

Indeed. 2 million tonnes == 2Tg. 2 million metre³ == 2hm³. The unit in the article is "cubic tonne". I mixed the whole thing without thinking. This is maybe adding weight (what a pun) to my original point though. Using the proper unit at the source.

Reply on news.ycombinator.com