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."

Comments

New tests for gravity.

[G4from128k]

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. We all think gravity changes with 1/r^2 and is irrespective of material composition, but do we really know that this rule works for ALL ranges of mass, distance, and material?

Inquiring physicists want to know and this innovation could help them know it.

Re:New tests for gravity.

[marcus]

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.

Re:New tests for gravity.

[QuantumFTL]

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

Re:How many...

[Patrik_AKA_RedX]

Au: 197g/mol
10E-18 / 197 = 5.076x10E-21 mol
5.076x10E-21 x 6.022x10E23 = 3056.8 gold atoms.

Tests will be difficult

[Spamalamadingdong]

At that scale, influences like Van der Waals forces become far more powerful than gravity. Reading the pull of gravity with all the EM-related forces at work seems like a very, very difficult job.

Re:Weight Via Chaos Theory

[Baron_Yam]

Actually, this has already been done... though with optics. You take large numbers of measurements of 'nothing' and note the random static produced by the sensor. You can then subtract the average noise from the average of a large number of measurements of something and get an accuracy level theoretically beyond the ability of your instrument.

Re:Zeptogram?

[cicadia]

About 1.4x10^-11 microns/zL on the highway, 8x10^-12 or so in the city. Although I think that mileage is more commonly measured in zeptolitres per 100 Angstroms these days.