How do electrons keep out of the nucleus?

[penguinraider]

Apart from inertia and a nucleus' "gravity" (I invisage it's like the planets revolving around the sun), are there any other factors that keep the electrons from being attracted to the protons and crushing into the nucleus?

 

[dextercioby]

Gravity doesn't contribute with (almost) nothing.It can be totally neglected.The model with planets orbitting the Sun it's good for planets orbitting the Sun,it's perfectly useless (due to incorrectness) in atomic description.

The laws of Quantum Mechanics (its axioms & results) applied to the atom give all the proof needed for atomic stability.

Daniel.

 

[jtbell]

We've been having a discussion about this in the next forum down the hall:

https://www.physicsforums.com/showthread.php?t=65636

I suggest you check it out and post any further questions there.

[Argh, Daniel must be able to type faster than I can!]

 

[marlon]

Here is how you should look at the fact that electrons do not crash onto the atomic nucleus and why they don't radiate : there is no radiation of electrons in an atom. The electrons move indeed in orbitals with a certain velocity (no acceleration). Now the fact that electrons do not fall into the nucleus due to the Coulombic interaction has to do with the fact that there is an equilibrium in both potential and kinetic energy.

Electrons that are "closest" to the nucleus have a lower potential energy (more negative) but they move in the orbitals with higher speed (higher kinetic energy). Once you look at electrons further waway from the nucleus, the potential energy rises and the velocity (and therefore the kinetic energy) lowers. In the end there is an equilibrium between those two.

marlon

 

[Antiphon]

Here is how you should look at the fact that electrons do not crash onto the atomic nucleus and why they don't radiate : there is no radiation of electrons in an atom. The electrons move indeed in orbitals with a certain velocity (no acceleration). Now the fact that electrons do not fall into the nucleus due to the Coulombic interaction has to do with the fact that there is an equilibrium in both potential and kinetic energy.

Electrons that are "closest" to the nucleus have a lower potential energy (more negative) but they move in the orbitals with higher speed (higher kinetic energy). Once you look at electrons further waway from the nucleus, the potential energy rises and the velocity (and therefore the kinetic energy) lowers. In the end there is an equilibrium between those two.

marlon

We should be careful. Accelerating a charge is not enough to produce
radiation. If it were, then electrons at rest in a gravity field would radiate since they are being constantly accelerated.

Furthermore, atomic quantum orbitals are anything but constant velocity
configurations, since a change in either direction or speed implies acceleration.

A better answer is needed for why electrons don't radiate in atomic orbitals,
and it is a purely quantum mechanical explanation (which I myself am still looking for.)

 

[ZapperZ]

We should be careful. Accelerating a charge is not enough to produce
radiation. If it were, then electrons at rest in a gravity field would radiate since they are being constantly accelerated.

Furthermore, atomic quantum orbitals are anything but constant velocity
configurations, since a change in either direction or speed implies acceleration.

A better answer is needed for why electrons don't radiate in atomic orbitals,
and it is a purely quantum mechanical explanation (which I myself am still looking for.)

Well, since we are trying to "be careful" here, let's also make sure we be extra careful in saying that the atomic orbitals somehow implies a "velocity" or speed of anything. It doesn't. By saying such things, we are already implicitly implying a well-defined charged particle moving around. You don't have such things until a position measurement is done. Before then, an electron in an s-orbital, for example, has no well-defined position and identity. Rather, based on the wavefunction alone, it is "spread out" in a uniform sphere around the nucleus. So the electron is everywhere simultaneously (which is connected to the Schrodinger Cat-type puzzlement - another illustration that things in QM are interconnected). This is how we get an angular momentum of zero for the s-orbital - from the geometry of the orbital itself.

This is another illustration where our social language can cause many confusion in trying to describe things that have no linguistic equivalent. As soon as we say "electron moves in an orbit", a whole range of implications kick in. We automatically imply that there is this well-defined object that we can track along the way and moving in a well-defined trajectory. QM implies no such thing, at least as far as atomic orbitals are concerned. We have seen a whole zoo of evidence where an "electron" can simultaneously spread itself into many locations to produce unclassical effects (bonding-antibonding bands, etc.) .

Zz.

 

[marlon]

We should be careful. Accelerating a charge is not enough to produce
radiation. If it were, then electrons at rest in a gravity field would radiate since they are being constantly accelerated.

Furthermore, atomic quantum orbitals are anything but constant velocity
configurations, since a change in either direction or speed implies acceleration.

A better answer is needed for why electrons don't radiate in atomic orbitals,
and it is a purely quantum mechanical explanation (which I myself am still looking for.)

Well, indeed maybe i shoudn't have written constant velocity...That is indeed not correct. But the point really is the equilibrium between potential and kinetic energy.

marlon

 

[nebulan]

elctric field is the answer...the protons are positive
the elctron are negative
if the elctron were putted in a right place and shooted in a right velocity it will orbit the proton and never hitting it
..by the way

its a bad example saying that the atomic structure are like planets

its not right to say that the elctrons orbiting the nucleas is like planets revolving around the sun

the elctron was thoght a particle but sceintests discoverd that it is a wave

its true

qm quantum meachanicks is filled with uncorrect statics

but it helped a lot for understanding the atomic srtucture

 

[dextercioby]

elctric field is the answer...the protons are positive
the elctron are negative
if the elctron were putted in a right place and shooted in a right velocity it will orbit the proton and never hitting it
..by the way

its a bad example saying that the atomic structure are like planets

its not right to say that the elctrons orbiting the nucleas is like planets revolving around the sun

the elctron was thoght a particle but sceintests discoverd that it is a wave

its true

qm quantum meachanicks is filled with uncorrect statics
but it helped a lot for understanding the atomic srtucture

I think those are false claims...If u have a source to document your affirmation,please,post them and i'll accept it/them.

Till then,please,do not post erroneous claims...

Daniel.

P.S.It would help your cause a lot,by spelling English properly.We have a spell checker,in case u haven't noticed...

 

[nebulan]

ok danial
first of all sorry i am a bad speeler and that won't change
second its true i never tell lies i always make sur iam right

and these are the sites so you can make sur for your own self
http://www.telp.com/qw1.htm

http://www.rit.edu/~photo/IFS/index-pages/IFS-20.html





http://www.colorado.edu/physics/2000/index.pl

 

[dextercioby]

1.Electron is not a wave.
2.Quantum Mechanics "is filled" with correct descriptions of nature.

There's a giant thread in the QM & QFT forum about "What's wrong with QM?".Maybe you'd like to share your views with us.Who knows,we might learn something...


Waiting you there,

Daniel (sic!).

P.S.Good thing it's not "denial" :

 

[inha]

ok danial
first of all sorry i am a bad speeler and that won't change
second its true i never tell lies i always make sur iam right

and these are the sites so you can make sur for your own self
http://www.telp.com/qw1.htm

http://www.rit.edu/~photo/IFS/index-pages/IFS-20.html





http://www.colorado.edu/physics/2000/index.pl

link 1 doesn't explicitly say electrons are waves.
link 2 uses a bad wording.
link 3 doesn't explicitly say electrons are waves.

 

[Ba]

the elctron was thoght a particle but sceintests discoverd that it is a wave

its true

How does a wave have a spin? I know an electron does.

 

[nebulan]

its wave are collided to a ball shape
A physicist named Erwin Schrödinger showed that electrons are really waves
check this scientest Erwin Schrödinger and youl know that an elctron is a wave

 

[dextercioby]

The classical equivalent of photon spin is what we call independent polarization directions of an em wave.Incidentally,in QFT,when describing a photon,we use the wording "polarization states" when talking about helicity eigenstates of the photon...

Daniel.

 

[inha]

its wave are collided to a ball shape
A physicist named Erwin Schrödinger showed that electrons are really waves
check this scientest Erwin Schrödinger and youl know that an elctron is a wave

wow. how did you reach this conclusion from schrödinger's formulation of quantum mechanics?

 

[dextercioby]

A correct description of the concept of "electron" is offered by the quantum theory of the Dirac field.Period.

Daniel;

 

[Dragongod]

the problem is no field of science has ever explicitly stated whether or not and showed logically how, a field is not made up of mass, matter. To say a field can exist in of itself is to say that energy can exist without mass. Its also to imply that F=ma is wrong, as well as, E=mc^2 because both these formulas indicate that a field must actually be comprised of particles (mass, matter) - that energy and mass cannot exist without each other.

 

[marlon]

1.Electron is not a wave.

I really wonder where people keep getting the idea that an electron is a field. Especially in QFT ?

marlon

 

[dextercioby]

The electron is a quanta of the electron field:a Grassmann \left(\frac{1}{2},0\right)\oplus \left(0,\frac{1}{2}\right) irreductible representation of \mbox{SO(3,1)} to which certain conditions are imposed (see the solving of Dirac's equation for free field).

Daniel.

 

[marlon]

The electron is a quanta of the electron field:a Grassmann \left(\frac{1}{2},0\right)\oplus \left(0,\frac{1}{2}\right) irreductible representation of \mbox{SO(3,1)} to which certain conditions are imposed (see the solving of Dirac's equation for free field).

Daniel.

Yes and every good student should ask the question : WHY ?

Well, the answer is once again group theory.

When studying the Lorentz group (the group that arises when you 'add up' both rotations and Lorentz boosts) one can prove that the generators will obey certain commutation relations conform the SO(3,1)-algebra.

When studying this algebra we can prove that (by writing these generators in a 'certain' way : J+, J-) [J+,J-] = 0. This results tells us that the representations generated by these two operators are 'independent' of each other. More formally, the SO(3,1) breaks up into two SU(2)-algebra's. Why SU(2), well that's because of how J+ and J- are defined (which we won't discuss). Just imagine that the two operators obey the rules 'for belonging to this SU(2)-algebra'

Basically this means that once you know the SU(2)-representations, you also know the SO(3,1)-representations. The generators of these algebra's are the famous Pauli-matrices.

Each SU(2) representation is denoted by a number j which has values 0,1/2,1,3/2,...and it contains 2j+1 objects \phi _{m} (and m is equal to -j,-j-1,...,0,1,...,j) that transform into each other under such transformations generated by the Pauli-matrices.

For SO(3,1) we need two such j's : (j+,j-) and the representations are (0,0), (1/2,0), (0,1/2), (1,0),...

The (1/2,0) and (0,1/2) are the socalled spinor representations. If have explained what a spinor is, in my journal.As you can see, a spinor has two components (2*1/2+1) and can be represented by a 2*1-matrix (\phi_{1,2}, the component-notation of such a matrix). But Dirac proved (when quantizing the Dirac field of which the fluctuations are the electrons) that the 'correct' spinor (that describes an electron) needs 4 components. Why ? Well, because of parity conservation. The two representations that we are talking about are interchanged when parity is changed. Thus we work with BOTh representations at once : this is what dexter wrote in his post : (1/2,0) + (0,1/2). We basically put two (Weyl)spinors together to form a Dirac spinor.

regards
marlon

 

[marlon]

Besides, i would like to add this : people always ask how do electrons orbiting the nucleus prevent from falling in ? Well, this question itself contains incorrect formulations. the electron does NOT orbit the nucleus. Just look at the lowest energy orbital : the s-orbital. It is a sphere around the nucleus. So , prior to any kind of measurement, the electron is basically everywhere around the nucleus.
Same goes for any other orbital (ofcourse the have another shape)


QM proves us that the kinetic energy is higher when being closer to the nucleus, but the potential energy is lower (more negative). The sum of these two really yields a stable equilibrium throughout all energy levels.

marlon

 

[marlon]

And finally (then i will stop whinning) people always mix QFT with QM. A wave function that describes an electron is not a wave that IS an electron. It just contains the electron-properties. This is QM

In QFT, particles arise as fluctuations of fields but the fields themselves ARE NOT particles. Particles arise (and also forces) as actual vinrations of these fields. Just think of the mattress analogy that i have used throughout my entire journal

regards
marlon

 

[Dragongod]

Yes but that is the very problem QM and QFT are in disagreement. As well QFT never actually explains how its possible for particles to arise out of fluctuations of fields. Also, it never explains how fields exist without being comprised of particles, basically it never offers a formula, that is consistant with reality, and that shows force can exist without mass, particles.

 

[dextercioby]

The concept of quantization itself turns classical fields into quantum fields.What's so particular about these quantum fields ?The fact that their energy is quantized and appears under the form of particles...

As for

it never offers a formula, that is consistant with reality

That's simply bull****.

Daniel.

 

[Dragongod]

Really, as far as I know its not bull but I may be just lacking education on this matter. If it is bull could you please please post the formula(s) that it offers to prove this.

 

[dextercioby]

I think you have to prove your statement...

Daniel.

 

[Dragongod]

i didn't make a statement to prove. All i said was that as far as i know, there are no formulas in QFT that prove force can exist without mass or that energy can exist without mass. If there are can you please post them so i will be corrected.

 

[dextercioby]

What's force in QFT?

Daniel.

 

[marlon]

Yes but that is the very problem QM and QFT are in disagreement. As well QFT never actually explains how its possible for particles to arise out of fluctuations of fields. Also, it never explains how fields exist without being comprised of particles, basically it never offers a formula, that is consistant with reality, and that shows force can exist without mass, particles.

Look, i am not going to argue with you but clearly your understanding of QFt is totally wrong. QM is incorporated in QFT. QFT really is the 'unfication' of both QM and special relativity. You don't have to believe me, just ask anyone else or read Anthony Zee's book QFT in a Nutshell.

As to the fluctuations : just google for the Casimir effect, which is a REALTIME prove that such fluctuations must exist.

regards
marlon

 

[Dragongod]

Thanx Marlow and i will goodle it to find out about how they prove fluctuations must exist and how they actually do exist. But my question is if a field exist in QFT which is defined as being massless, not comprised of particles and just force, then what is formula to justify that? How can QFT say that fields aren't particles if they don't have a formula to justify that force, which is what fields are, doesn't have to be made of particles i.e. have mass.

 

[marlon]

Thanx Marlow and i will goodle it to find out about how they prove fluctuations must exist and how they actually do exist. But my question is if a field exist in QFT which is defined as being massless, not comprised of particles and just force, then what is formula to justify that? How can QFT say that fields aren't particles if they don't have a formula to justify that force, which is what fields are, doesn't have to be made of particles i.e. have mass.

Look the problem really is that you are thinking too much in classical terms here. Now, i don't want to explain all this because i want to go watch TV but i really urge you too browse through my journal. You'll find many texts there as to why fields are actually used and how particles arise as fluctuations of these fields. You will also find many links to online QFT-courses that are reliable. Other then repeating myself i urge you to read those before making such claims. I am not saying you are wrong to ask those questions, it's just that you really need to know what you are dealing with, prior to start making those claims

regards
marlon

 

[Dragongod]

I have looked at your journal, maybe i didn't look hard enough, but i didn't really find an answer to my question. I don't care much about the fluctuation thing. My question is if QFT uses the label FIELD and defines a field as having force without mass, then there should be a formula in QFT that represents this relationship. As far as i know, there is no formula in QFT that explicitly describes what FORCE is. If there is please let me know.

 

[dextercioby]

There's no such thing as force:neither in special relativity*,nor in quantum mechanics,ergo not in QFT.


Daniel.

P.S.*U could build in relativistic physics a 4 vector f^{\mu}=mw^{\mu} [/tex],using the acceleration 4 vector,however it's not really used...(okay,2 examples i can think of:Lorentz 4-force and Abraham-Lorentz 4-force,however the name & the notation f^{\mu} doesn't appear).

 

[Dragongod]

See I knew it. That was my whole point. How can they say a field has force if they don't have a definition of force! Does anyone see a little problem with that?

"In QFT, particles arise as fluctuations of fields but the fields themselves ARE NOT particles. Particles arise (and also forces) as actual vinrations of these fields."
-----how can QFT use the word field without saying what it is and how its possible for it to exist without particles. IT DOESN'T MAKE SENSE

 

[dextercioby]

A field (classical em.one) has both momentum & energy.It has a 4 tensor:energy-momentum.9 of its 16 components form the famous Maxwell tensor and describe the ability of the classical em field to transmit momentum...

Daniel.

 

[dextercioby]

See I knew it. That was my whole point. How can they say a field has force if they don't have a definition of force! Does anyone see a little problem with that?

"In QFT, particles arise as fluctuations of fields but the fields themselves ARE NOT particles. Particles arise (and also forces) as actual vinrations of these fields."
-----how can QFT use the word field without saying what it is and how its possible for it to exist without particles. IT DOESN'T MAKE SENSE

It does.A classical em.field can exist in vacuum.Please study the classical theory of fields.A purely relativistic theory.You'll understand many things.

Daniel.

 

[Dragongod]

I read a few thing on classical theory of fields. It still doesn't make sense to me. It never answers what is a vacuum. It gives a definition but it doesn't ANSWER what it is(how its possible to exist and what its properties are and how that fits in with the rest of the laws of physics). Also it doesn't explain how a Field can have momentum and energy but somehow not have mass. I don't get how they justify that.

 

[Dragongod]

maybe i didn't read well enough but if it does explain how a field has that ability (can exert momentum and have energy without mass) can you explain to me how.

 

[dextercioby]

Einstein's formula can account for massless particles (or fields)

E^{2}=m^{2}c^{4}+\left|\vec{p}\right|^{2}c^{4}

Daniel.

P.S.Mass equal zero doesn't mean energy =0,nor momentum =0.

 

[Dragongod]

E^2 = m^2*c^2 + [p]^2*c^2? does this translate to Energy squared equals mass squared multiplied by the speed of light squared plus (momentum) squared multiplied by the speed of light squared. If it does then all its really saying is that energy equals mass and momentum. Therefore it would be proving that a Field cannot exist without mass i.e. particles.

 

[dextercioby]

Particles can be massless.Period.Photons,gluons,gravitons and their SUSY partners are all massless...

Daniel.

 

[Dragongod]

LOL they are not massless. Photons are said to have relativistic mass for some reason that i don't remember but its mass nonetheless. Glouns do have mass they are the particles that generate the force to keep leptons and quarks "stable." And as for gravitons, as far as i know, nobody really discusses or have proved whether or not they do or don't have mass. As far as i know its still very controversial as to whether they actually exist. According to me, I do believe gravitons exist but as far as science goes they still debate it.

 

[dextercioby]

Nope.Please read.You're definitely out of it completely.

Daniel.

 

[Dragongod]

HAHAH if you say so. but that formula you posted in no way shows that fields can exist without particles.

 

[dextercioby]

Classical fields exist without particles...Period.


Daniel.

P.S.Classical fields are irreductible representations of the \mbox{SO(3,1)}.Typically,functions

\mathcal{Q}^{a}:\mathbb{M}_{4}\rightarrow \mathcal{A}

,where \mathbb{M}_{4} is the flat Minkowski space and \mathcal{A} is an algebra...

 

[Dragongod]

thanx for the formulas but what i am trying to get at is that these formulas are based on assumptions. None of the theories have actually been "observed" such as Minkowski space. Its completely based on space-time, a term Einstein coined but didn't actually prove.

 

[Entropy]

It never answers what is a vacuum.

Say what? I suppose you need a definition of "is" aswell? It's empty space, devoid of matter, nothingness. What is a force? Something that accelerates a mass.

LOL they are not massless.

He means they have no rest mass. Techniquely they just have momentum because having mass implies that they have infite energy because it moves at the speed of light. Plus the term "mass" is simply a quality of something that resists change in motion. Since light always moves at c it is hard to say it has mass.

If it does then all its really saying is that energy equals mass and momentum. Therefore it would be proving that a Field cannot exist without mass i.e. particles.

No, from your tone I getting the idea that you think mass and momentum are one and the same. Mass is a quality that resists change in motion. While momentum is the product of mass and velocity.

 

[feynmann]

Well, since we are trying to "be careful" here, let's also make sure we be extra careful in saying that the atomic orbitals somehow implies a "velocity" or speed of anything. It doesn't. By saying such things, we are already implicitly implying a well-defined charged particle moving around. You don't have such things until a position measurement is done. Before then, an electron in an s-orbital, for example, has no well-defined position and identity. Rather, based on the wavefunction alone, it is "spread out" in a uniform sphere around the nucleus. So the electron is everywhere simultaneously (which is connected to the Schrodinger Cat-type puzzlement - another illustration that things in QM are interconnected). This is how we get an angular momentum of zero for the s-orbital - from the geometry of the orbital itself.

This is another illustration where our social language can cause many confusion in trying to describe things that have no linguistic equivalent. As soon as we say "electron moves in an orbit", a whole range of implications kick in. We automatically imply that there is this well-defined object that we can track along the way and moving in a well-defined trajectory. QM implies no such thing, at least as far as atomic orbitals are concerned. We have seen a whole zoo of evidence where an "electron" can simultaneously spread itself into many locations to produce unclassical effects (bonding-antibonding bands, etc.) Zz.

>> You don't have such things until a position measurement is done. Before then, an electron in an s-orbital, for example, has no well-defined position and identity.

Is this the so-called Copenhagen interpretation? Why is the Copenhagen interpretation being taken for granted here?

 

[ZapperZ]

>> You don't have such things until a position measurement is done. Before then, an electron in an s-orbital, for example, has no well-defined position and identity.

Is this the so-called Copenhagen interpretation? Why is the Copenhagen interpretation being taken for granted here?

Don't take it for granted. Why don't you find <x> for the such a situation and draw up your own conclusion?

Zz.