Comments on: World's most perfect spheres

By: duke_leeto_III

duke_leeto_III — Thu, 04 Oct 2012 23:19:35 +0000

shrink earth down to the size of a cue ball and earth would be smoother

By: Sean Weatherford

Sean Weatherford — Wed, 30 Nov -0001 00:00:00 +0000

Englarge the spheres to the size of the Earth. Use the official equatorial diameter of 7926.41 miles as a reference. The resulting difference between lowest point (Marianas Trench) and highest point (Mount Everest) would then be 15.7 feet.

By: Wilson!

Wilson! — Wed, 30 Nov -0001 00:00:00 +0000

I call BS on at least some of this. If these were the spheres mentioned in the story, I highly doubt they would be in anything other than a clean room, and certainly not held in the palm of someone’s hand (gloved or not). And I doubt “bearded scientist guy” would be in anything other than a full-body bunny suit. Just the act of taking them out and showing them off would affect the mass and diameter.

Now, the orbs in the pics might be stand-ins, or something to that effect, but I seriously doubt these are the real McCoy.

By: Anonymous

Anonymous — Wed, 30 Nov -0001 00:00:00 +0000

It’s “metre”, not “meter” in Australia and nearly all other parts of the world. For an article that discusses precision and metric units, it’s more than a little ironic that such flaws have been introduced. Editors of Make, please fix these typos; you’re making me cringe and ruining your own scientific cred.

By: Mike

Mike — Wed, 30 Nov -0001 00:00:00 +0000

Earth ins’t perfectly round. It’s vaguely spherical, but the oceans actually rize and fall a long way due to lunar gravity. Also the earth is wider at the equator than anywhere else.

By: RocketGuy

RocketGuy — Wed, 30 Nov -0001 00:00:00 +0000

This isn’t a misspelling, it’s a linguistic gulf from the divergence of American English and UK/AU/NZ English(which probably also diverge from each other a bit, I have no data there though).

English, in general, is quite flexible which allows for some of it’s success as a language. However, this does introduce the interesting interplay of slight differences in spelling and more importantly, definition.

Try comparing billions sometime…

By: elliottpayne.com

elliottpayne.com — Wed, 30 Nov -0001 00:00:00 +0000

The processed used to make these things is surprisingly simple.

I used to be a machinist the company that made one of the original “perfect” spheres and the process is actually kind of ghetto. Put a steel (or silicone in this case) ball between two cone shaped abrasive wheels & spin. If the bearing used in the spinning process has a true enough axis, you’ll get what you’re looking for.

http://en.wikipedia.org/wiki/Professional_Instruments_Company

Also, metrology is as much about statistics as it is about actual measuring instruments.

By: oskay

oskay — Wed, 30 Nov -0001 00:00:00 +0000

NIST publishes a *very good* guide on the recommended use of the use of the SI: http://physics.nist.gov/Pubs/SP811/ , in which “meter” is still preferred as the (US) spelling.

Since this is a cultural difference, calling our spelling a “flaw” is not helpful, and referring to it as a “typo” is snarky at best.

Wikipedia has an interesting discussion of (some of the) spelling differences between American English and British English:

http://en.wikipedia.org/wiki/American_and_British_English_spelling_differences

By: Sean Michael Ragan

Sean Michael Ragan — Wed, 30 Nov -0001 00:00:00 +0000

Certainly you’re free to call BS any time you like. Personally, if I’m ever going to take anybody’s word on anything, it’s likely to be these guys, as the whole point of their project is to be as exactly right about one measurable quantity as is humanly possible, and they’ve spent years and millions doing it. As for your claim that “taking it out and showing it off would affect the mass and diameter,” I can’t say if I agree or disagree. But I’m curious why you think so.

By: RocketGuy

RocketGuy — Wed, 30 Nov -0001 00:00:00 +0000

I was kinda flabbergasted how simple the process is for telescope mirror grinding was too, even for a 1/10th wave mirror. Long and boring, but simple.