What is the smallest physically-possible voltage that can be detected or processed given the state of today's technology?

rickman wrote: > On Jun 1, 10:33 pm, ItsASecretDummy
>> On Mon, 01 Jun 2009 17:40:20 -0700, John Larkin >>
>> >>> Single-electron transistors can sense, well, single electrons. >>> John >> PMTs can be good enough to detect single photon events. > > Hmmm... I have a $35 digital multimeter that can measure exactly 0 > volts!
How exactly?
Jerry
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ndoftheuniverse.org> wrote:

The usual way. It's not a magic voltmeter!
Rick
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rickman wrote:

I meant not "How, exactly", but "exact to what extent".
Jerry
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Ahh... the resolution question again. He already answered that one too, you just have to read what was written.
Another resolution question is the guys trying to determine the age of the universe.
I would think it quite hard to look that far back because things would be so distorted that even your determination of how far back you are "seeing" could be off an order of magnitude. 13.5 Billion years could really be 135 Billion.
See you on 12/20/2012.
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The Great Attractor wrote:
...

13.5 billion is so last year! The number now is 13,500,000.001.
Jerry
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The Great Attractor wrote:

Have fun... Javascript calculator of the many distances involved in cosmology http://www.astro.ucla.edu/~wright/CosmoCalc.html
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wrote:

It would have to be to be able to measure zero volts, since such feats are not possible.
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wrote:

No... it cannot. In fact, nothing can.
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On Jun 1, 5:40 pm, John Larkin

Are there any devices that can detect, receive, record, playback, modulate/demodulate, transmit and/or otherwise process signals with peak-to-peak amplitudes around 1 femtovolt?
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(snip)

Since it is usually power, and not voltage, that is the limiting factor, it might be possible if the current is high enough.
If you go through a transformer, or a series of them, to get to a more usual voltage and current range, then it might work. I would say that it is likely not possible to measure femtovolts DC, but likely possible AC.
-- glen
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Can't you always chop a DC current to produce an AC current? Even if the current is very high, the fact that it is at a very low voltage makes it hard to get any of that current to flow through your measuring device, even if it is a transformer.
I suppose that you could pass the entire current through the measuring device and then calculate the voltage by knowing the impedance... But I don't see how having a high current help a direct measurement of a low voltage.
Rick
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On Tue, 2 Jun 2009 06:17:53 -0700 (PDT), GreenXenon

Yes, your FM receiver. Usually takes 3 or more though.
We call them radios.
Satellite and deep space radio waves exhibit even less energy. That what the big concentrator dishes are for.
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On Tue, 02 Jun 2009 18:47:14 -0700, GoldIntermetallicEmbrittlement

Femtovolts, with an FM receiver? Good ones need microvolt or so. A 3 dB noise figure, optimistic for a radio, is ballpark 1 nV RMS noise per root Hz, and an FM radio has a couple of hundred KHz bandwidth.
AlwaysWrong.
John
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< Femtovolts, with an FM receiver? Good ones need microvolt or so. A 3 < dB noise figure, optimistic for a radio, is ballpark 1 nV RMS noise < per root Hz, and an FM radio has a couple of hundred KHz bandwidth.
How about traditional satellite TV? As I remember, it is about six watts per channel. If the signal covers most of the continental US, a 10m dish has about 1/(500000)**2 the area of the US, so about 6W/2.5e11 or about 2.4e-11W At 75 ohms that is about 40uV. I would expect that to be a lot less than FM radio with 100kW transmitters.
On the other hand, my cable modem has about +16dBm input at 75 ohms. About 1.7V, maybe enough for a small light bulb. (I believe that is only for the specific signal it is receiving, not counting the hundreds of other cable channels.)
-- glen
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glen herrmannsfeldt wrote:

Try that without the feed horn and dish to supply a fair amount of gain.
The early 'Galaxy' birds were 10 watts per transponder.
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Go bugger yourself, you spamming pile of shit.
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wrote:

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Oh my god please fuck off from sci.physics. We do not want you.
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Eric Gisse wrote:

Just kill file the idiot. If no one replies, they will give up. Trolls thrive on attention, so you have to starve them.
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On Tue, 02 Jun 2009 00:19:17 -0400, "Michael A. Terrell"

But he asked a sensible question this time.
John
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