Can an electron be identified?

Use this forum to discuss the philosophy of science. Philosophy of science deals with the assumptions, foundations, and implications of science.
Belindi
Moderator
Posts: 919
Joined: September 11th, 2016, 2:11 pm

Re: Can an electron be identified?

Post by Belindi » April 14th, 2017, 5:00 am

Felix wrote:Here's an an interesting thread on quora.com re: the reality of electrons: http://ow.ly/ZzMl30aQM6c

Thanks Felix, that is super!

-- Updated April 14th, 2017, 5:06 am to add the following --
A Poster He or I wrote:I notice, Belindi, that no one has attempted a direct answer of your OP's last question, "But multiple electrons aren't different aspects of the same are they?" I'm in agreement with Felix that we are ultimately just talking about mathematical constructs here, but I freely acknowledge that the effects of what we call electricity are a very real part of our empirical experience, and that the "electromagnetic field" is our best model of electricity, and that the "players" on that field are these troublesome electron thingies.

The thing about fields in physics, unlike those in football stadiums, is that they exist in complementarity with their particle "players." There is no field without the presence of the particles, while the behavior of the players is only understandable in terms of the field they produce. In other words, the mere idea of an individual electron is merely a convenient (or more likely obfuscating) extrapolation of the Pauli exclusion principle. There is circumstantial evidence that all of space and time are merely an emergent epiphenomenon of something much more fundamental (I'm referring here to the consequences of the empirical proofs of Bell's Inequality). So our fundamental concepts of extension and duration are in some sense unreal. The would bode well for an opinion that all electrons are the "same" electron.
I think you are saying, A Poster He or I, that whether electrons are real or not is about which aspect we view then from, or to put this another way which question we ask. So electrons exist as units in a field and the field also exists, and that those are complementary.

User avatar
-1-
Posts: 712
Joined: December 1st, 2016, 2:23 am

Re: Can an electron be identified?

Post by -1- » April 14th, 2017, 5:03 pm

Felix wrote:
-1- said: All I know is that at the moment you are debating completely factual scientific findings, over which the scientific community has consensus and overwhelming evidence
What is the "completely factual finding on which there is scientific consensus"? That the electron is, as you said, a discrete form of matter? (that is what we are debating). There is certainly no consensus about that, as it displays both particle and wave like properties.
You got me there, Felix.

But it's not the case of a "nothing", electron is not energy, and it can be detected. You contested the detectibility... electrons can be detected as discrete matter.

You're right about electrons displaying both wave like and particle-like existence. But this is not the same as to say that it is only a math concept.
"You can always live without a lover, but you can't love without a liver."

Felix
Posts: 1786
Joined: February 9th, 2009, 5:45 am

Re: Can an electron be identified?

Post by Felix » April 15th, 2017, 1:25 pm

The latest fluid dynamic studies indicate that the electron is both a particle and a wave, not sure what that means....

"a wavepacket travelling along a phase vortex in an Eulerian fluid obeys Maxwell's equations, is emitted and absorbed discretely, and can have linear or circular polarisation."

Duh! Why of course, all my sailing experience on the Eulerian sea should have told me that!! :oops:
"We do not see things as they are; we see things as we are." - Anaïs Nin

Steve3007
Posts: 4237
Joined: June 15th, 2011, 5:53 pm
Favorite Philosopher: Eratosthenes
Location: UK

Re: Can an electron be identified?

Post by Steve3007 » April 17th, 2017, 5:27 am

A little contribution from me:

As has been noted by others the only way to understand the concept that we refer to as an electron is to remember that it is a collective name for a set of observations and some mathematical relationships between those observations. This includes observations that have already been made and recorded and observations that the mathematical relationships predict would be made in the future if we were to arrange our apparatus in a particular way and look in a particular direction.

As such the idea of "seeing" an electron means making some of those observations. In that sense (as Poster pointed out earlier) we "see" electrons all the time. I am "seeing" them right now because the best way to describe and predict the presence and behaviour of this computer in front of me (or, in fact, all the other things in front of me) involves the concept of the electron, among many other things. To put it another way: All observations of all the concepts that we think of as "things" are indirect to some degree or other.

If we wanted what we might arbitrarily regard as a slightly less indirect way of viewing an electron we might try doing one of those experiments with cathode ray tubes that we did in high school physics. They sometimes had a little metal Maltese Cross in the middle of them (remember that?). When various things were done involving other apparatus such as power supplies and wires, some of those CRTs - the ones that were filled with a particular kind of diffuse gas - exhibited a strange glowing line inside them whose position could be changed using a magnet or electric field. In that situation, the best explanation for the little green line is that electrons are flowing from the cathode to the anode and bumping into things on the way with the end result that those things emit light that enters our eyes.

Does this mean we're seeing electrons? "No" some might say. They might say we're just seeing the photons and inferring the presence of electrons as one possible explanation for the presence of those photons. Or maybe some might say we're seeing the atoms that emit the photons and making a similar inference. Or some such thing. But if we say that of electrons - that their existence is only inferred from other things that we see directly - then we have to say pretty much the same thing about everything else we think we see. So, as a shorthand, we might as well just say that we see the electrons. In the same way, as a shorthand, I say I can see a table in front of me rather than going to all the trouble of obtusely saying that photons that I assume to be entering my eyes (due to various chemical/electrical signals in my brain) are probably there due to having bounced off a chair. That would be an odd thing to say wouldn't it? In everyday life the shorthand is the norm. But in physics, in order to make sense of things, we have to remember that it is a shorthand.


On the subject of identical electrons: Those mathematical models also tell us that electrons, like many other particles, are literally identical to each other. The mathematical models that are most successful in describing and predicting observations (the models of Quantum Theory, and particularly Statistical Mechanics) work on the assumption that this is true not just for practical purposes, but is true in principle. As has also been pointed out earlier, this can lead to the idea that, in a sense, there is only one electron in the universe. But, as with everything else, I would say that a statement like "there is only one electron in the universe" stands or falls by its utility in describing and predicting observations, albeit very indirectly. To say something like "yes but is it really true that there is only one electron in the universe?" just leads ultimately to confusion. It's either useful or not useful to say it.

-- Updated Mon Apr 17, 2017 10:46 am to add the following --

Note: In the penultimate paragraph, above, I've just noticed I mixed up "table" and "chair"! That was a mistake. I hope it doesn't cause any confusion. Just read them both as "table" or as "chair". Which one you choose doesn't much affect the point I was trying to make.
"Even men with steel hearts love to see a dog on the pitch."

Belindi
Moderator
Posts: 919
Joined: September 11th, 2016, 2:11 pm

Re: Can an electron be identified?

Post by Belindi » April 17th, 2017, 11:40 am

But do electrons have mass? I know that atoms have mass. and can be manipulated. But can electrons be manipulated, or does that hypothesis not make sense?

Steve3007
Posts: 4237
Joined: June 15th, 2011, 5:53 pm
Favorite Philosopher: Eratosthenes
Location: UK

Re: Can an electron be identified?

Post by Steve3007 » April 17th, 2017, 12:03 pm

Yes electrons have mass. 9.1 x 10-31 kgs of it. A small portion of the mass of the atoms of which they are a part. Yes electrons can be manipulated, in the sense that they can be caused to do things by taking certain actions. We're manipulating electrons all the time. I'm doing it now by bashing the outer electrons in the outer atoms of my finger tips against the outer electrons of the outer atoms of the keys on my keyboard.
"Even men with steel hearts love to see a dog on the pitch."

Belindi
Moderator
Posts: 919
Joined: September 11th, 2016, 2:11 pm

Re: Can an electron be identified?

Post by Belindi » April 18th, 2017, 6:02 am

Steve3007 wrote:Yes electrons have mass. 9.1 x 10-31 kgs of it. A small portion of the mass of the atoms of which they are a part. Yes electrons can be manipulated, in the sense that they can be caused to do things by taking certain actions. We're manipulating electrons all the time. I'm doing it now by bashing the outer electrons in the outer atoms of my finger tips against the outer electrons of the outer atoms of the keys on my keyboard.
Then is it true to say that in order to make this technology possible some scientist had first to separate one electron from another electron? I mean, does the fact of mass imply that whatever has mass is also a discrete entity?

If the latter is the case then the electromagnetic field is analogous to fire which is process of which the flame is what is a discrete mass. Is that correct?

Felix
Posts: 1786
Joined: February 9th, 2009, 5:45 am

Re: Can an electron be identified?

Post by Felix » April 18th, 2017, 9:56 pm

Belindi: Then is it true to say that in order to make this technology possible some scientist had first to separate one electron from another electron?
To be precise, separate all electrons from an atom save one, and determine that solitary electron's mass relative to the mass of the atom's nucleus.
Does the fact of mass imply that whatever has mass is also a discrete entity?
No, it is only a discrete entity in the minds of men, it is not discrete in nature.
"We do not see things as they are; we see things as we are." - Anaïs Nin

Belindi
Moderator
Posts: 919
Joined: September 11th, 2016, 2:11 pm

Re: Can an electron be identified?

Post by Belindi » April 19th, 2017, 4:10 am

Felix wrote:
Does the fact of mass imply that whatever has mass is also a discrete entity?


No, it is only a discrete entity in the minds of men, it is not discrete in nature.
Yes I understand that mass and entities are mind dependent categories as far as we can know. However, allowing for that, are electrons, which like other entities have mass, as much discrete entities as atoms are discrete entities?

ChanceIsChange
Posts: 28
Joined: December 15th, 2016, 7:36 am

Re: Can an electron be identified?

Post by ChanceIsChange » April 19th, 2017, 6:03 am

Belindi wrote:Regarding the last sentence, if any electron E can have a locus assigned to it such that it can't occupy the same space at the same time as another electron E2 then it's not identical with E2.
The premise is false; because of Heisenberg's uncertainty principle, it is not possible to assign a precise position to an electron. Therefore, the conclusion need not be correct. In fact, it is false according to quantum mechanics. All electrons are the same, which can even be verified empirically as follows:

Consider two distinct connected chambers A and B of the same size and two electrons e1 and e2.
If e1 isn’t identical to e2, then there are 4 distinct constellations, all equally probable: e1 in A and e2 in A, e1 in A and e2 in B, e1 in B and e2 in A, and e1 in B and e2 in B. Consequently, the probability of having both electrons in chamber A would be ¼.
However, if e1 is actually identical to e2, then there are only 3 distinct constellations, all equally probable: both electrons in A, both electrons in B, and one electron in each chamber. Consequently, the probability of having both electrons in chamber A would be 1/3.
Experiments have shown the latter to be the case.

I suggest the following descriptions of the three constellations to remove the apparent counterintuitivity of the sameness of electrons:
Rather than saying that there is an electron and another electron in chamber A and no electron in chamber B, we should say that the electron manifests twice in chamber A and zero times in chamber B. Even better, we should say that the electron 2-manifests in chamber A and 0-manifests in chamber B to eliminate the illusion of two manifestations as distinct entities. Here, the number n in “n-manifestation of the electron in chamber X” should simply be considered a property of the manifestation of the electron in chamber X.
Similarly, we should say that the electron 0-manifests in chamber A and 2-manifests in chamber B rather than that there are two electrons in chamber B and none in A, or that the electron 1-manifests in chamber A and 1-manifests in chamber B rather than that there is one electron in each chamber.

Felix
Posts: 1786
Joined: February 9th, 2009, 5:45 am

Re: Can an electron be identified?

Post by Felix » April 19th, 2017, 6:46 am

Belindi: are electrons, which like other entities have mass, as much discrete entities as atoms are discrete entities?
That depends: would you consider a wave a discrete entity?

"We must be clear that when it comes to atoms, language can only be used as in poetry." — Niels Bohr
"We do not see things as they are; we see things as we are." - Anaïs Nin

Steve3007
Posts: 4237
Joined: June 15th, 2011, 5:53 pm
Favorite Philosopher: Eratosthenes
Location: UK

Re: Can an electron be identified?

Post by Steve3007 » April 19th, 2017, 7:42 am

Belindi:
Yes I understand that mass and entities are mind dependent categories as far as we can know. However, allowing for that, are electrons, which like other entities have mass, as much discrete entities as atoms are discrete entities?
Short answer: yes. As much and as little. The mathematical models that we use to describe entities like electrons are not fundamentally different for electrons, atoms or double decker busses. If you want to you can calculate the DeBroglie wavelength of a double decker bus and the extent to which it will diffract when it passed through a tunnel, just as you can for an electron passing through a slit.
"Even men with steel hearts love to see a dog on the pitch."

User avatar
Consul
Posts: 776
Joined: February 21st, 2014, 6:32 am
Location: Germany

Re: Can an electron be identified?

Post by Consul » April 19th, 2017, 9:44 am

Belindi wrote:
Consul wrote:A perfectly natural class is one whose members are qualitatively identical, i.e. (intrinsically) indistinguishable duplicates, such as the class of electrons: every electron is perfectly similar to any other electron. The classes of elementary particles and the ones of chemical elements are perfectly natural.
Regarding the last sentence, if any electron E can have a locus assigned to it such that it can't occupy the same space at the same time as another electron E2 then it's not identical with E2. This ontology is different from the ontology of minds and bodies. Minds and bodies do occupy the same space and time as each other because they are two aspects (perspectives) of the same. But multiple electrons aren't different aspects of the same are they?
According to Leibniz' Principle of the Identity of Indiscernibles, qualitative identity entails numerical identity. But this principle is arguably false. However, there are different interpretations of it, depending on the kinds of properties in question, e.g. intrinsic properties vs. extrinsic properties.
Since all electrons are intrinsically indistinguishable, they cannot be individually identified in terms of their intrinsic properties. They could be individually identified in terms of their extrinsic (relational) properties, such as their respective locations in space. However, as quantum physics teaches us, it's pretty problematic to determine the locations of single particles. So single electrons may not be individually identifiable at all. Does this mean that an electron lacks individuality and identity? I don't think so, because identification/identifiability is one thing and identity is another. As Joseph Butler famously said, "Everything is what it is and not another thing." Every electron has its own (self-)identity or "haecceity" simply by being numerically different from all other electrons: where there are two or more electrons, there are two or more numerically different electrons. Simple as that!

For those interested: Identity and Individuality in Quantum Theory
"We may philosophize well or ill, but we must philosophize." – Wilfrid Sellars

Steve3007
Posts: 4237
Joined: June 15th, 2011, 5:53 pm
Favorite Philosopher: Eratosthenes
Location: UK

Re: Can an electron be identified?

Post by Steve3007 » April 19th, 2017, 11:18 am

Just for fun:

DeBroglie wavelength:

λ = h / p

(λ = wavelength. h = Planck's constant. p = momentum.)

The internet told me that a Routemaster London double decker bus has a mass of about 12 tonnes. That's 12000 kgs. If it's travelling at 10 ms-1 then its momentum is 12000 X 10 = 120000 kg.ms-1. So its DeBroglie wavelength is given by:

λ = 6.626 X 10-34 X 120000

= 7.9512 X 10-29 metres

Pretty small. But not zero.

Note: the smaller the momentum (and therefore the smaller the velocity) the longer the wavelength, which equates to a greater uncertainty in the position: Heisenberg's uncertainty principle.

---

Consul:
...Does this mean that an electron lacks individuality and identity? I don't think so, because identification/identifiability is one thing and identity is another. As Joseph Butler famously said, "Everything is what it is and not another thing." Every electron has its own (self-)identity or "haecceity" simply by being numerically different from all other electrons: where there are two or more electrons, there are two or more numerically different electrons. Simple as that!
I don't think comments like this about the identity of an electron really mean anything unless they describe and predict things that can be observed. The notion that electrons are identical exists because it explains actual observations like those illustrated by ChanceIsChange above. A mathematical model in which they were not identical would not fit observed reality.

I think if you want to make a statement such as "Every electron has its own (self-)identity or "haecceity" simply by being numerically different from all other electrons: where there are two or more electrons, there are two or more numerically different electrons. Simple as that!" you'd have to describe an experiment whose results can only be explained if that statement is true.

This is why I suggested earlier that purely ontological questions about how things "really are" such as "are electrons really identical?" serve no purpose and just lead to confusion unless they're tied to what can be observed.
"Even men with steel hearts love to see a dog on the pitch."

User avatar
-1-
Posts: 712
Joined: December 1st, 2016, 2:23 am

Re: Can an electron be identified?

Post by -1- » April 21st, 2017, 10:57 pm

Correct me if I am wrong, and I shall stand corrected, but I sorta imagine that the following are scientific findings in qm.

1. Electrons do couple up.
2. Each electron couple has opposing spins to each others' (as a concept).
3. If you reverse the spin of one electron, the other of the couple will reverse its.
4. Other electrons don't change their spins, only these two.

According to this, electrons are distinct, identifiable. You work out the logic, I'm too tired now to come down to that task.
"You can always live without a lover, but you can't love without a liver."

Post Reply