Wave or Particle: Unraveling the Mystery of Electrons

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In summary, the conversation discusses the concept of electrons as both waves and particles and the difficulties in understanding this duality. The use of quantum mechanics and the Schrödinger equation to describe the behavior of electrons is also mentioned, along with the idea of orbitals as equiprobable surfaces rather than equipotential surfaces. The conversation ends with a clarification on when these concepts are typically taught in education and a discussion on the wave-particle duality.
  • #1
peeyush_ali
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waves..or particles..??

I didnt really get when people say that electrons are "waves" .. when we say like "shape of an "s" orbital is spherical...and shape of "p" orbital is a dumbbell and so on.." we actually wanted to show that the surface of an s orbital some how describes the the trajectory of an electron..
well i know electrostatics..so can I conclude that those surfaces are "equipotential surfaces" for they have a constant magnitude of energy ...??
well..i'm really dumbstruck when my friends argue about the electrons that they re sometimes waves and sometimes particles...
I wonder if an electron were a particle like how they teach in classical physics, will it have dimensions..like if someone says a "particle" the immediate figure that comes in our mind is of a "spherical billiard ball" which is very much a sphere with some radius..

If we take a piece of a metal and we zoom a part of it with a highly powerful microscope, then can we see electrons ..?
what is quantum physics all about..?
and what does it has to do with these things..? like Heisenberg principle..
HOW can a particle on very high velocity have wave nature..?
 
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  • #2


The orbitals are found using quantum mechanics. In posing the problem, we still assume that the electron is a point charge and we solve for the orbitals using a wave equation called the Schroedinger equation. Electrons are particles with wave-like properties that arise from Schroedinger's equation. But the orbitals represent a probability density of finding the electron in a volume in space when measured. So the orbitals do not represent a smearing of the electron or a cloud, they just represent the likely positions that we will find the electron.
 
  • #3


well..i'm really dumbstruck when my friends argue about the electrons that they re sometimes waves and sometimes particles...

rightly so,...it is not something that's makes "sense" in the classical way of thinking. "No one understand quantum mechanics" I believe Feynman said.

But is has a very useful set of tools for predicting subatomic behavior that matches experimental observations remarkably well..

If you really want to blow your mind, read about positrons, the antiparticle of the electron: how can THAT be?? And how can they pop into existence from NOTHING? It's a crazy subatomic world!

If we take a piece of a metal and we zoom a part of it with a highly powerful microscope, then can we see electrons ..?

Interesting question.
An electron microscope might be the finest detail instrument we have...is that still correct??
If so, it's not so easy to detect one electron with another even if it were "visible"...I guess scattering is the basic tool we still rely upon?? One of the 'difficulties' with QM is that the observations you make and the measurements you choose determine the outcome of what you may find...even if you were to "observe" an electron at a pinpoint location a moment later it will be in a different state and likely a different location.
 
  • #5


Naty1 said:
An electron microscope might be the finest detail instrument we have...is that still correct??

Atomic force microscope could be the instrument with the finest detail.

Back to the topic, please note that in QM, there are no "wave-particle duality" in describing these things. We don't switch pictures from wave to particle, and back, when we describe light, electrons, etc. There's one, consistent description, no duality.

Zz.
 
  • #6


Are the orbitals "equipotential surfaces" due to electrostatic interactions between protons and electrons..??
 
  • #7


Well, equipotential surfaces would be a good analogy, but they're really more like "equiprobable surfaces" (not a technical term) - that is, surfaces on which the probability per unit volume of finding the electron is constant.

I assume you're familiar with the electric potential field around, say, a proton. In an electric potential field, of course, each point in space has a certain value that represents the potential energy of a unit charge at that point. The wavefunction in quantum mechanics is also a field; each point in space has a certain value that represents the "amplitude" of finding the electron at that point. The amplitude is a complex number, and the square of its magnitude represents the probability per unit volume of finding the electron at that point. The greater the wavefunction's magnitude in a region, the more likely you are to find the electron in that region.

When they say that an s orbital has a spherical "shape," it really means that the corresponding wavefunction is spherically symmetric. So surfaces of constant wavefunction magnitude would be spheres. In contrast, a p orbital has a dumbbell shape, which means that the surfaces of constant wavefunction magnitude would be dumbbells. P orbital wavefunctions are not spherically symmetric, of course. All these shapes come from mathematical functions called spherical harmonics, which are part of the solution of the Schrödinger equation in a central potential (like that of a proton or atomic nucleus).
 
  • #8


thanks alot.. I'm a +2 student..we ve been taught classical physics...can u tell me when will i be learning about what all u hav mentioned such as amplitude..and probability of finding electrons and all... i mean at which level..??
 
  • #9


It depends on how the educational system works where you live. (I don't know what a "+2 student" is.) In the USA, students usually start studying this stuff seriously in the second year of university.
 
  • #10


Code: 
Back to the topic, please note that in QM, there are no "wave-particle duality" in describing these things. We don't switch pictures from wave to particle, and back, when we describe light, electrons, etc. There's one, consistent description, no duality.

hmmm, what do u mean when u say there is no 'wave particle duality'? Light behaves as a wave and as a particle, so do electrons and other particles. Are you referring to the fact that an experiment with light will churn out either a wave or particle description but not both?
 
  • #11


ZapperZ said:
Atomic force microscope could be the instrument with the finest detail.

Back to the topic, please note that in QM, there are no "wave-particle duality" in describing these things. We don't switch pictures from wave to particle, and back, when we describe light, electrons, etc. There's one, consistent description, no duality.

Zz.

What are you talking about? I'm very confused by this statement.
 
  • #12


in QM we have the wavefunction, which is the only entity you" need". We neven go from particle to wave and vice versa in the realm of QM.
 
  • #13


Phrak said:
What are you talking about? I'm very confused by this statement.

My guess to what he is saying is that when people think of dual wave-particle, they sometimes imagine it as an either/or characteristic. Light behaves like a particle since it is a photon but when it comes to diffraction and interference, then it behaves like a wave. In quantum mechanics, there is no distinction, the behavior is always the same, it is just that in some situations it will behave like a macroscopic particle and in others a macroscopic wave.

EDIT: Ahhh.. malawi beat me to it.
 
  • #14


what is meant by a "wave function"?? and "only entity" ??
 
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  • #16


Are entities like "electrostatics" not allowed in QM ??
 
  • #17


I would not call electrostatic an entity...

but the question is not what is allowed or not, the question is if it makes sense.. and electrostatics does not make sense in QM.

What I suggest, is that you pick up a textbook on QM, a really easy one, like

Quantum Physics For Dummies

The Quantum World: Quantum Physics for Everyone

The Quantum World: Quantum Physics for Everyone

HFGL
 
  • #18


thanks for suggesting..
 
  • #19


Almost all questions on "how/why do particles behaves as waves" etc have already been asked and answered 1000 000 times. If you are a physics student, you will eventually have formal quantum mechanics classes.

cheers
 
  • #20


I know I keep banging on about it (the Lord forgive me) but the only way to actually make sense of the wave-particle duality stuff is to assume that there are particles and waves (de Broglie-Bohm view).

Now of course you are not morally obliged to assume this (and the officially sanctioned pigheadedness says that you mustn't - no! - but for no really good reason that would stand up in court). However if you don't want to then you mustn't ask for QM to make sense, because it can't and doesn't. It just gives a probabilistic summary of the results without any clear idea of what is going on - and that is fine for all practical purposes.

Now it is usually claimed/implied that quantum mechanics proves that a reasonable understanding of the world in this sense is impossible, and that it is impossible to write down the laws of nature in terms of a clear ontology. The existence of de Broglie-Bohm theory proves that such claims are false, even embarassingly false, because de Broglie-Bohm theory is an utterly straightforward completion of quantum mechanics. Indeed, if you study the theory closely, one sees that it is just is quantum mechanics. Nothing added, nothing taken away.

Just that when you use the word 'particle', you have to mean it.
 
  • #21


For those unfamiliar with the terminology, zenith8's de Broglie-Bohm theory is more commonly know as the Bohm interpretation.
 
  • #22


It would not make any sense if there are particles and waves. It leads to a whole heap of new questions. How is this Broglie Bohm theory different from the accepted version? I admit I have some deep misgivings about the accepted Copenhagen interpretation but it has met with a lot of success. Anyone wishing to cough up a new interpretation has a lot to prove.
 
  • #23


math_04 said:
It would not make any sense if there are particles and waves. It leads to a whole heap of new questions. How is this Broglie Bohm theory different from the accepted version? I admit I have some deep misgivings about the accepted Copenhagen interpretation but it has met with a lot of success. Anyone wishing to cough up a new interpretation has a lot to prove.

Oh God. Sometimes you lose the will to live.

It's not a new theory - it's existed in almost its entirety since 1927 (before Copenhagen, note). The only reason it wasn't adopted at the time was for political reasons and the prevailing positivistic philosophy in the 1920s. The history of why it hasn't been adopted since is a fascinating study in the psychology of groups and misplaced hero-worship.

It gives exactly the same results as the standard theory - the only difference being that everything now makes sense and you don't have to have these endless discussions of 'what does the double slit experiment/tunnelling/Heisenberg uncertainty etc. etc. mean. So before you say 'it would not make any sense if there are particles and waves' then please think and tell us why not.

Though it superficially looks like you have to add extra maths and so on, that is just not the case. The only difference is as I said - when you say 'particle' mean it. i.e. the square of the wave function is the probability that the electron actually is at a certain point, rather than the probability of being found there in a suitable measurement. Everything else follows (the electron trajectories traveling along the streamlines of the probability current given by the standard theory etc.).

My favourite reference is this http://www.tcm.phy.cam.ac.uk/~mdt26/pilot_waves.html" which is reasonably comprehensible to the novice and (at times) very amusing.

Hootenanny said:
For those unfamiliar with the terminology, zenith8's de Broglie-Bohm theory is more commonly know as the Bohm interpretation.

Indeed, or sometimes the pilot-wave theory,or Bohmian mechanics, or the causal interpretation, or the ontological interpretation, or..
 
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  • #24


math_04 said:
Code: 
Back to the topic, please note that in QM, there are no "wave-particle duality" in describing these things. We don't switch pictures from wave to particle, and back, when we describe light, electrons, etc. There's one, consistent description, no duality.

hmmm, what do u mean when u say there is no 'wave particle duality'? Light behaves as a wave and as a particle, so do electrons and other particles. Are you referring to the fact that an experiment with light will churn out either a wave or particle description but not both?

Phrak said:
What are you talking about? I'm very confused by this statement.

People, once again, I will point out to you the Marcella paper that I've cited numerous times on here (do a search if you don't believe me). In there, using QM and light as photons, one can get ALL of the wave behavior, such as diffraction and interference, without having to switch gears from "particle" to "wave". There is no "duality" in QM as far as both descriptions are concerned, unlike in classical mechanics where they are not compatible with each other.

There aren't two separate descriptions for photons, electrons, etc.. in QM. There's only ONE. It is this one description that produces ALL of the known observations for all these particles.

Zz.
 
  • #25


zenith8 said:
It's not a new theory - it's existed in almost its entirety since 1927 (before Copenhagen, note). The only reason it wasn't adopted at the time was for political reasons and the prevailing positivistic philosophy in the 1920s. The history of why it hasn't been adopted since is a fascinating study in the psychology of groups and misplaced hero-worship.
The version I heard was that at the time the pilot-wave theory wasn't sophisticated enough to deal with many-body problems particularly well, and Pauli tore it to strips such that even De Broglie himself adopted the CI, at least for a period of time. I'd be fairly sceptical as to whether or not Einstein and Schrodinger would lose a battle of "hero worship" quite so easily.
 
  • #26


ZapperZ said:
In there, using QM and light as photons, one can get ALL of the wave behavior, such as diffraction and interference, without having to switch gears from "particle" to "wave". There is no "duality" in QM as far as both descriptions are concerned, unlike in classical mechanics where they are not compatible with each other.

Sorry, what did you mean by "in classical mechanics ... they are not compatible with each other." ? What's not compatible? Is it the "duality"?

Are waves not compatible with particles in classical mechanics?
 
  • #27


muppet said:
The version I heard was that at the time the pilot-wave theory wasn't sophisticated enough to deal with many-body problems particularly well, and Pauli tore it to strips such that even De Broglie himself adopted the CI, at least for a period of time. I'd be fairly sceptical as to whether or not Einstein and Schrodinger would lose a battle of "hero worship" quite so easily.


The version you heard is partly deliberate misinformation. And, believe it or not, misinformation partly spread by Bohm himself - who as late as his 1993 "Undivided Universe" textbook wrote that de Broglie only did the one-body problem in 1927, and that he, Bohm, was the first to do the full many-body pilot-wave theory in 1952. In fact the only thing de Broglie didn't have was a clear understanding of what we now call decoherence (which was invented by Bohm for his 1952 papers) and so he wasn't able to treat measurement interactions involving macroscopic objects properly.

Believe it or not de Broglie's presentation was actually quite well received at the 1927 Solvay conference (see the recent book by Valentini and Bacciagaluppi, which incidentally contains the first translation of the proceedings into English, as well as vast amounts of relevant discussion). Pauli's objection regarding inelastic scattering turned out to be incorrect (though it wasn't his fault - he was using a misleading and incorrect optical analogy of Fermi's).

My understanding of the above is based on lecture 7 of http://www.tcm.phy.cam.ac.uk/~mdt26/pilot_waves.html" entitled "Not even wrong. Why does nobody like pilot-wave theory?" which contains an excellent and concise summary of all the events that you refer to. His 'alternative universe' presentation of what might have happened if Pauli had been paying more attention is quite amusing..

De Broglie certainly had all the equations in 1927, and so the priority is definitely his. Valentini and Baccigaluppi make this point very strongly in their book. Towler goes even further and makes the case for not calling the thing "Bohmian mechanics" or the "Bohm interpetation" - he says one could call it de Broglie-Bohm theory, but the original "pilot-wave theory/interpretation" is probably better since no one who isn't French can pronounce Louis' surname.

Incidentally Einstein and Schroedinger weren't the heroes I was referring to. Didn't Schroedinger refer to the CI as 'a philosphical extravaganza dictated by despair?'
 
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FAQ: Wave or Particle: Unraveling the Mystery of Electrons

What is the wave-particle duality of electrons?

The wave-particle duality is a concept in quantum mechanics that explains the behavior of electrons. It states that electrons can exhibit both wave-like and particle-like properties, depending on the experiment being conducted.

How is the wave-particle duality of electrons tested?

The wave-particle duality of electrons is commonly tested through the famous double-slit experiment, which shows that electrons can behave like waves when passing through a barrier with two slits, creating an interference pattern.

What is the Heisenberg uncertainty principle?

The Heisenberg uncertainty principle is a fundamental principle in quantum mechanics that states that it is impossible to know both the position and momentum of a particle, such as an electron, at the same time with complete accuracy.

How does the wave-particle duality of electrons impact technology?

The wave-particle duality of electrons has had a significant impact on technology, particularly in the field of electronics. It has allowed for the development of devices such as transistors and semiconductors, which are essential components in modern electronic devices.

Can the wave-particle duality of electrons be explained by classical physics?

No, the wave-particle duality of electrons cannot be explained by classical physics. It is a phenomenon that can only be understood through the principles of quantum mechanics, which describe the behavior of particles on a subatomic level.

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