Can we observe 2 electrons at the same time?

[DARKSYDE]

My question comes from the heels of frustrated google searching and a half arsed attempt to pursued the search function on these forums to find my answer. So my apologies if I havnt given diligence it’s due.

My question is inspired by an episode of Space time, on PBS, regarding the one electron universe thought.

Yes I know I know..

I’ve managed to find the smallest observable measurement made to date involving an interaction with an electron reaction time leaving a proton ( I believe ? )

It was something like 5.83 x 10²¹

( P.S. ) I am using my phone to write this

I’d assume to measure two electrons at the exact same “time” we’d be talking about a Planck length .

Is that possible?

Thanks in advance!

 

[Drakkith]

I’d assume to measure two electrons at the exact same “time” we’d be talking about a Planck length .

There is always some uncertainty in any measurement, so it is not possible to measure two electrons at *exactly* the same time. Or at least it's not possible to know if we've done so.

 

[Nugatory]

We can, in principle, measure the positions of two electrons at the same and with arbitrary precision. But I'm not sure how you're getting to this question from a PBS episode (which generally shouldn't be taken too seriously) on the one-electron notion.

 

[DARKSYDE]

My question was inspired by an episode called spacetime on PBS about the one electron universe thought noted in a nobel prize speech: https://en.m.wikipedia.org/wiki/One-electron_universe.

So I thought why not observe 2 electrons at the same “time”.

 

[Nugatory]

So I thought why not observe 2 electrons at the same “time”.

There's nothing in the one-electron hypothesis that precludes detecting electrons at different points in space at exactly the same time, or that suggests that electrons will behave differently in any other way. We use the math of quantum field theory to predict how electrons will behave; the one-electron hypothesis is just a mental picture that we can form from a negative sign that's in the math and hence the results of our calculations no matter what mental picture we've formed.

And as Feynman and the wikipedia article mention, this particular mental picture requires an additional ad hoc assumption to explain away the observed excess of matter over antimatter.

(It's often a good idea to take a look at the talk page of a wikipedia article, and this one is no exception).

 

[DARKSYDE]

There's nothing in the one-electron hypothesis that precludes detecting electrons at different points in space at exactly the same time.

Nothing wrong with electrons ( plural ) in the one electron universe hypothesis.. you say..

Think about that would ya?

 

[Nugatory]

Nothing wrong with electrons ( plural ) in the one electron universe hypothesis.. you say..
Think about that would ya?

You may have missed a subtlety in the way I worded that... I didn't say there are two electrons, I said there are two electron detection events. That's not the same thing.

We have electron detector A and electron detector B at two different locations. They both report "I detected an electron" at exactly the same time.

You can explain this observation by saying that we have two electrons, one which was present when A triggered and one which was present when B triggered.

Or you an explain this observation by saying that there was one electron that was present when A triggered; then that electron traveled through space to detector B and back in time to before either detection; now the electron is in the right place at the right time to trigger B at exactly the same moment that A triggered.

Both explanations are consistent with the math, and there is no experiment, even in principle, that could tell them apart. The latter explanation is the one-electron hypothesis.

 

[ZapperZ]

This whole thread is extremely puzzling. It seems that everyone but me is clear on what is meant by "observe electron (or two electrons) at the same time". Observe WHAT property of the electron? This has never been clarified.

Are you trying to measure the position, momentum, charge, current, etc... of these two electrons "at the same time"? One doesn't measure "electron". One measures specific properties or characteristics of an electron or many electrons.

BTW, we can measure the charge of 2 electrons at the same time. Make a constriction in a superconductor and measure each Cooper pair as they pass through. Done!

Zz.

 

[DARKSYDE]

I thought my question was pretty clear?

 

[ZapperZ]

I thought my question was pretty clear?

It was clear to you.

Zz.

 

[DARKSYDE]

Ha, fair enough.

 

[DARKSYDE]

Since all electrons have EXACTLY the same charge and mass the only way we’d ever be able to tell them apart is to make to observations at the same time.

And by the same time I’d assume time to be in Planck terms.

Could we conclude that if we indeed observed 2 at the exact same time then the one electron universe could be proven wrong?

Or

Is there some inherent law enevitably prevents an observation at or lower than a plank length?

 

[ZapperZ]

Since all electrons have EXACTLY the same charge and mass the only way we’d ever be able to tell them apart is to make to observations at the same time.

And by the same time I’d assume time to be in Planck terms.

Could we conclude that if we indeed observed 2 at the exact same time then the one electron universe could be proven wrong?

Or

Is there some inherent law enevitably prevents an observation at or lower than a plank length?

Again, observe what?

What if I make ONE measurement of the charge and it comes out to 2e? Is this a "measurement of 2 electrons"? If it is, then I'm done! Cooper pairs, by definition, are entangled particles consisting of 2 "inseparable" electrons. There are enough experimental measurements (including SQUIDs applications) to show that the basic unit of charge in this case is 2e.

Zz.

 

[DARKSYDE]

Again, observe what?

What if I make ONE measurement of the charge and it comes out to 2e? Is this a "measurement of 2 electrons"? If it is, then I'm done! Cooper pairs, by definition, are entangled particles consisting of 2 "inseparable" electrons. There are enough experimental measurements (including SQUIDs applications) to show that the basic unit of charge in this case is 2e.

Zz.

What if you do! But at the same’ time’ do you understand? The same time. The exact same time..

 

[ZapperZ]

What if you do! But at the same’ time’ do you understand? The same time. The exact same time..

I make just ONE measurement of the charge. I get a unit of 2e? Isn't this a measurement of both charges "at the same time"? I did not make one measurement of charge for one electron and then a measurement of the other. It IS ONE, SINGLE measurement. Why is there an ambiguity of the "time" here?

Zz.

 

[DARKSYDE]

This is the smallest observable measurement we’ve made: https://www.google.com/amp/s/futuri...-smallest-division-of-time-ever-observed/amp/

It’s a fun read.

Hope it helps you understand the term measurement

 

[ZapperZ]

This is the smallest observable measurement we’ve made: https://www.google.com/amp/s/futuri...-smallest-division-of-time-ever-observed/amp/

It’s a fun read.

Hope it helps you understand the term measurement

But unfortunately, you don't understand what a "Cooper pair" is, and the significance that they are entangled.

They are so entangled and attached to one another, they can even go through a tunnel barrier together, hand-in-hand (look up Josephson current).

And isn't it funny that you are trying to teach an experimentalist what a "measurement" is?

Zz.

 

[DARKSYDE]

Maybe my question isn’t for you but I do appreciate your response and I’ll take responsibility for any confusion.

 

[Nugatory]

Since all electrons have EXACTLY the same charge and mass the only way we’d ever be able to tell them apart is to make to observations at the same time.

Even that isn't sufficient to tell them apart - two measurements at the exact same time doesn't preclude the hypothetical explanation I desribed above in post #7 of this thread.

You are right that electrons are indistinguishable; in fact that's part of why the one-electron hypothesis cannot be disproven. There's no way of labeling the electrons, so no way of distinguishing between the same electron observed in two different positions and two different electrons observed in those two positions.

And by the same time I’d assume time to be in Planck terms...
Is there some inherent law enevitably prevents an observation at or lower than a plank length?

The Planck length and time may not be what you're thinking they are. The wikipedia section on the physical significance of the Planck units is pretty good, but you may also want to read this Insights article: https://www.physicsforums.com/insights/hand-wavy-discussion-planck-length/

Could we conclude that if we indeed observed 2 at the exact same time then the one electron universe could be proven wrong?

No. See above, and especially the situation described in post #7 above. The one-electron hypothesis does not preclude electron detections in different places at exactly the same time.

 

[DARKSYDE]

No. See above, and especially the situation described in post #7 above. The one-electron hypothesis does not preclude electron detections in different places at exactly the same time.

Even if the resolution of time was at Planck scale?

 

[mfb]

Even if the resolution of time was at Planck scale?

Yes. The resolution does not matter.

This is the smallest observable measurement we’ve made: https://www.google.com/amp/s/futuri...-smallest-division-of-time-ever-observed/amp/

futurism is known for poor science journalism. Don't trust anything they write. The article is not even internally consistent.
> with an accuracy rate of up to 850 zeptoseconds.
> with an accuracy of a zeptosecond
And I don't find either number in the reference.

850 zeptoseconds are about 3 million times the (well-measured) lifetime of the Z boson.

 

[DARKSYDE]

Well dang.. thanks guys. Sorry I drug a half baked idea into the house. ( wags tail )

 

[alantheastronomer]

Even if the resolution of time was at Planck scale?

No, because as Nugatory stated in post #7, according to the single electron hypothesis, the one electron travels BACK in time to position #2 to be measured at the exact same time as the first measurement!