Slashdot Mirror
Weighing An Attogram
Roland Piquepaille writes "Researchers at Cornell University have reached a new level of precision by measuring objects with a mass of less than an attogram (10^-18 gram). They used a silicon cantilever oscillator to measure small dots of gold. But their real goal is to detect and identify viruses. The team also wants to reduce the size of the cantilever, extending the sensitivity well into the zeptogram (10^-21 gram) range. This summary contains more details and an image of a small gold dot resting on the silicon cantilever they used to achieve this breakthrough."
Au: 197g/mol
10E-18 / 197 = 5.076x10E-21 mol
5.076x10E-21 x 6.022x10E23 = 3056.8 gold atoms.
Your question reveals some confusion, perhaps produced by the wording of the article.
They are not "weighing" anything. They are measuring the mass of the gold. These are two different things. Gravity is not involved in the latter.
Good judgement comes from experience, and experience comes from bad judgement.
- W. Wriston, former Citibank CEO
If they can use this to measure very small forces on very small objects, they might be able to construct some interesting tests of gravitational fields or of quintessence.
I don't really think that this technology in its current form can measure the forces on a particle that size. If you read the article, it is measuring the mass by measuring the resonant frequency, not measuring the forces present on the object.
Yes I know that external forces can shift the frequency (due to nonlinearity) however I do not think that the precision of the device allows for measurement of such a weak effect.
This has little to do, as another poster metioned, with other forces masking things at this small scale, but rather with the fundamental nature of the measuring device.
Disclaimer: I'm a semester away from my BS in physics.
Cheers,
Justin
The problem with this is that your system is chaotic. If you measure it one way, you can't tell how it's going to turn out. If you measure it the other way, you also can't tell how it began.
And, the number of possibilities you have for a starting state would probably depend on just how sensitive your system is. If there's not many possibilities to choose from, then your system is probably insensitive enough to get an accurate measurement right up front.
But it's a cool idea that would probably make a good gimmick in a sci-fi story.
If tits were wings it'd be flying around.