> Dark matter is the mysterious, unknown substance that seems to make up the bulk of all the mass in the universe; for every 2 pounds (1 kilogram) of regular matter, there's roughly 10 pounds (5 kg) of dark matter.
The units here are pretty silly. They are only talking about proportions, so they could have gone with banana-equivalents, and it would still have worked.
The bananas you can buy in the West are all clones of each other. Their mass distribution is tight enough that it wouldn't make much of a difference given that the numbers in the article are only very approximate to begin with.
In any case, my point in the comment was that the unit is arbitrary, they are only talking about ratios. So any unit (or no unit at all) would do.
They could have just said "5 times as much" to save us the bother of doing the calculation ... which needs a tiny bit of care because of the dual units.
The calculation involves dividing 5 by 1; most people should be able to handle it.
Note that they've correctly not bothered with providing equivalent quantities in each unit - 5 kilograms is 11 pounds, not 10 pounds. This doesn't matter, because the ratio 10 to 2 is equal to the ratio 5 to 1.
But it does raise the question of why they provide pounds at all, and if they're going to, why not just say "for every pound (or kilogram) of matter, there are roughly 5 pounds (or kilograms) of dark matter".
> why not just say "for every pound (or kilogram) of matter, there are roughly 5 pounds (or kilograms) of dark matter".
Your suggestion is better writing. As for why? Likely the author and editors rushed the content or lack strong skills in this particular style of writing. The author Paul Sutter seems to have a strong background in writing. The original sentence is awkward enough that it looks like it was written by one person and edited by another.
> Dark matter is the mysterious, unknown substance that seems to make up the bulk of all the mass in the universe; for every 2 pounds (1 kilogram) of regular matter, there's roughly 10 pounds (5 kg) of dark matter.
If I had to guess, I bet it only originally had one set of units and an editor added converted units to match some style guide. I doubt that Paul would have originally gone with
> for every 2 pounds of regular matter, there's roughly 10 pounds of dark matter.
Because 2:10 ratio is not a natural thing to write. He's an astrophysicist who did post-doc fellowships in Paris and Italy, so most likely he submitted an article with SI units:
> for every 1 kilogram of regular matter, there's roughly 5 kilograms of dark matter.
And I bet a livescience.com editor changed that to pounds to match a US-centric style guide.
The units here are pretty silly. They are only talking about proportions, so they could have gone with banana-equivalents, and it would still have worked.