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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."
Another one today? After yesterday's hat trick? -scc
Now they can finnaly weigh George W's brain!! (or cock... take your pick it doesn't matter)
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.
Two wrongs don't make a right, but three lefts do.
How many atoms of gold is that?
Very fascinating! I love the picture.
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They Are Vermin Feeding On Each Other's Feces.
I Hate \.
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.
Scientists restrict study to entire physical universe; creationist
...finally a way to weigh my post-dot-com crash paycheck. :D
I had this idea, which I've never implemented, of weighing items with extreme precision using a chaotic system. Since the chaotic system is sensitively dependent upon initial conditions, it should be possible to take measurements over a short period of time and work backwards mathematically to one of several possible initial weights. Eliminate those values that are not possible via other means (negative weights, far too heavy, far too light), and you should end up with an extremely accurate initial weight.
I'm not sure that it would really work in practice, but I just thought it was a neat idea, and vaguely related to the authors' use of an oscilator.
Perhaps if they were able to make the position of the oscilator at any time sensitively dependent on initial conditions, they could invent such a measurment tool (e.g. swing another weight in and out based on the position of the oscilator to slightly modify the local gravity in a nonmodal fashion that would make the oscilator sensitively dependent upon its weight and its inital position)
My differential equations work is so far gone, I couldn't even begin to measure this mathematically anymore.
The world will not get better through technology. We must seek to be better people.
And people complain that the Imperial system doesn't make any sense... How many micrometers per zeptoliter does your car get?
A virus is what we doctors call very very small. So small in fact it could not possible have made off with an entire leg.
This lobster was alive when it hit the frothy, boiling water.
How much would an attogram cost to send at Western Union? How many letters in an attogram anyway? Can I write normally or should I abbreviate with alotta yotta-yotta-yottas?
Are attograhams good with marshmallows and chocolate?
Tadum pum!
Eat at Joe's.
Now I can figure out what smells so good in my crotch. Maybe I can get it in a bottle, make it stronger and spray it all over.
I can see it now: Crotch in a Bottle, by Calvin Klein
The zeptogram was never as popular as the grouchogram. People only use it because it's better looking.
Damn little bastards will become weight concious and go on a diet just to elude detection.
But their real goal is to detect and identify viruses.
Maybe they should license this technology to Microsoft?
I've got more mod points and GMail invi
Let me tell you, I'm very impressed. I tried doing this and I could never pull it off. No matter how many diets I tried and how many hours I spent on the treadmill, I could never get down to one attogram. So, to you dedicated researchers who managed to weigh an attogram... congratulations, and good luck in your modeling career.
All it takes is nukes and nerves.
A technique like the one you mention is very common in many measuring applications: it's called oversampling followed by lowpass filtering.
Essentially, you're trading bandwidth for accuracy: the lower you make your lowpass bandwidth, the more you "average out" the noise, and the more accurate your measurement can become. However, the downside is that your bandwidth is very small, which causes your measuring time to be very large (you'll have to wait for your lowpass filter to complete at least a reasonable portion of its step-response).
The above implies that there is a limit on low tight you can make your lowpass filter: the characteristic timescale of your lowpass filter must be larger than that of your actual phenomenon (not: noise) related signal, or else the process itself it "too fast" and the actual signal is also filtered out by your lowpass filter.
Example: if you have a small amount of atoms that you want to weight, then having a too-large measuring time to obtain a 0.1% (or whatever) accuracy on the mass doesn't make sense if on the timescale of your measurement more than 0.1% of the material evaporates.
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