# Why don't an atom's electrons fall into the nucleus and stick to the protons?

• 414 Replies
• 174704 Views

0 Members and 1 Guest are viewing this topic.

#### Sarah Raphaella Rodgers

• Guest
##### Why don't an atom's electrons fall into the nucleus and stick to the protons?
« on: 26/10/2009 09:30:10 »
Sarah Raphaella Rodgers asked the Naked Scientists:

I'm a 16 year old Chemistry student. My Chemistry class has been focusing on the periodic table recently. I know that protons are positively charged, neutrons are neutral, electrons are  negatively charged and that atoms are mostly empty space. I also know for magnets opposites attract.

So why don't electrons stick to protons instead of flying around the nucleus? Magnets do it, so why can't atoms?

What do you think?
« Last Edit: 07/01/2010 04:22:51 by chris »

#### Mr. Scientist

• Neilep Level Member
• 1451
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #1 on: 26/10/2009 10:58:54 »
It has to do with the uncertainty principle. Because the electron cannot have a defined position in the nuclei of atoms means that it must occupy every other space within the atom in a wave of possibilities. If the electron was positioned with great certainty within the nuclei of atoms, their momenta becomes infinitely uncertaint. But instead, they seem to have energy-orbits inside of atoms which determine the chemical struture of the universe. Another interesting thing to note is that electrons could not be in the center of atoms, because if they where, matter would drastically sink in size.

We already know of nature objects which undergo this process, and they go by the name of neutron stars. In classical mechanics, electrons couple so strongly with protons that they should collapse all the time; and would in classical physics mean that every nucleus of every atom would gobble up the electrons in about 100 microseconds.

''God could not have had much time on His hands when he formed the Planck Lengths.''

̿ ̿ ̿ ̿̿'\̵͇̿̿\=(●̪•)=/̵͇̿̿/'̿'̿̿̿ ̿ ̿̿ ̿ ̿

٩๏̯͡๏۶

#### Vern

• Neilep Level Member
• 2072
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #2 on: 27/10/2009 11:29:02 »
When I was 16 people like Einstein and Schrodinger were reassuring us that we need not worry; the Copenhagen interpretation and Quantum Theory were too weird to make any real difference. Now we are a half century into Physics becoming Quantum theory to the exclusion of reality even. Causality was abandoned because Quantum theory can't survive if we insist upon it.

There is a cause for quantum phenomena just as there is a cause for uncertainty.  Philosopher David Hume trashed causality with his view that no matter the times we observe an event and its precursor we can never be certain that such an event will follow a future precursor of the same nature. Philosopher Emanual Kant insisted that there is a cause for every event, however; it is just that we may never know that cause with certainty.

Edit: The cause of all quantum phenomena is that the electric and magnetic amplitude that space can support is a finite value; all photons peak at this value. Max Planck observed this. But because we did not demand causality, we imagined the Quantum nature of the universe without even considering its cause.

Uncertainty has been boiled down to the statement that it is impossible to know both the position and the momentum of anything absolutely. The more you know about the position of something, the less you can know about its momentum.

Books have been written about the implications of this. The link describes the cause of uncertainty. The quote below is the meat of it.

Edit: I should point out that the causes mentioned are my speculation; you won't find them in physics books. []

The electromagnetic fields that comprise a photon are in a state of constant change. This change drives the central point of a photon forward through space. We measure the photon's path to be that of the central point, but the fields exist spatially around the photon at an amplitude that is greatest close to the point and diminishes as the square of distance away from the point.
When this photon nears its target, churning electrons belonging to atoms in the target begin to sense the photon's approach. Some electromagnetic fields in the electrons will be in good phase relation with the approaching photon. Among this huge jumble of moving electrons, some will be more inclined to absorb the photon's fields than others. Those most inclined will probably not be dead centre in the photon's path.
« Last Edit: 27/10/2009 13:52:39 by Vern »

#### Vern

• Neilep Level Member
• 2072
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #3 on: 27/10/2009 13:47:02 »
Quote from: Sarah Raphaella Rodgers
So why don't electrons stick to protons instead of flying around the nucleus? Magnets do it, so why can't atoms?
The present state of physical science does not allow "why" questions. Any answer will have to be speculative. I have an answer to the question that works well for me.

There has never been found any substance of an electron that is smaller than its electromagnetic radius. This radius is much larger than a proton. So if observations are correct, and electrons only exist at their electromagnetic radius, they would consist of a hollow shell about 12 times larger than a proton. The electron would engulf the proton and form a dynamic dance with the proton's charges.

This is speculative, but it explains the observations.
« Last Edit: 27/10/2009 13:48:57 by Vern »

#### Homely Physicist

• Jr. Member
• 11
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #4 on: 01/11/2009 02:32:13 »
It has to do with the uncertainty principle.

I'm afraid not. It's actually a result of two physical phenomena.

1) Pauli exclusion principle

This states that two fermions must be distinguishable i.e. you can always tell them apart. In practice, this means they must have at least one different quantum number. This restricts electrons into their shell structure. For example, consider hydrogen. The first shell (s- shell) has quantum numbers (1,1,1) and (1,1,-1). This is why two electrons, at most, can occupy the s- shell. These number combinations are easily derivable by solving the Schrodinger wave equation for hydrogen.

2) Entropy

Processes in physics tend to increase the entropy of the universe. Energy likes to go from ordered states to disordered (like how a ball wants to roll down a slope). A proton and an electron is more energetically favourable than a neutron. The decay of neutrons this way is known as beta decay. In order to 'squash' together a proton and an electron into a neutron you need to supply a large amount of energy, as well as overcome the electron degeneracy force (as you're probably going to try it with a large collection of atoms rather than waiting millions of years for a single electron to pair up). This occurs inside neutron stars.

#### Vern

• Neilep Level Member
• 2072
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #5 on: 01/11/2009 03:40:45 »
Principles do not cause things; principles merely describe the happenings. We tend to think of principles and theories as causes; they can not be causes; their use is in describing the happenings. [] I'm just trying to keep folks honest.
« Last Edit: 01/11/2009 03:43:09 by Vern »

#### Mr. Scientist

• Neilep Level Member
• 1451
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #6 on: 01/11/2009 15:33:42 »
It has to do with the uncertainty principle.

I'm afraid not. It's actually a result of two physical phenomena.

1) Pauli exclusion principle

This states that two fermions must be distinguishable i.e. you can always tell them apart. In practice, this means they must have at least one different quantum number. This restricts electrons into their shell structure. For example, consider hydrogen. The first shell (s- shell) has quantum numbers (1,1,1) and (1,1,-1). This is why two electrons, at most, can occupy the s- shell. These number combinations are easily derivable by solving the Schrodinger wave equation for hydrogen.

2) Entropy

Processes in physics tend to increase the entropy of the universe. Energy likes to go from ordered states to disordered (like how a ball wants to roll down a slope). A proton and an electron is more energetically favourable than a neutron. The decay of neutrons this way is known as beta decay. In order to 'squash' together a proton and an electron into a neutron you need to supply a large amount of energy, as well as overcome the electron degeneracy force (as you're probably going to try it with a large collection of atoms rather than waiting millions of years for a single electron to pair up). This occurs inside neutron stars.

I am sure Hawking himself said the Uncertainty Principle had something to do with it.

Either way you're wrong, the pauli explusion principle has nothing to do with electrons falling into the nuclei of atoms. It's a process which eliminates one fermion energy level to another. This happens everywhere, not only inside an atom. And entropy also has nothing to do with it.

''God could not have had much time on His hands when he formed the Planck Lengths.''

̿ ̿ ̿ ̿̿'\̵͇̿̿\=(●̪•)=/̵͇̿̿/'̿'̿̿̿ ̿ ̿̿ ̿ ̿

٩๏̯͡๏۶

#### Mr. Scientist

• Neilep Level Member
• 1451
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #7 on: 01/11/2009 15:36:37 »
Just in case you would like an example of the exclusionary principle ordinary in nature, it even happens when two electrons come close to each other in space. It's closely related to the wave function, which is actually one main reason why the electron does not fall into the nuclei of atoms; specifically because they are not located to any particular region of space, which would induce a collapse of their superpositioned states. They are ''arranged'' within their superpositioning because of energy levels. But the exclusion principle is not the prime cause of either the wave function or the fundemental reason why particles do not fall into the nuclei of atoms.

''God could not have had much time on His hands when he formed the Planck Lengths.''

̿ ̿ ̿ ̿̿'\̵͇̿̿\=(●̪•)=/̵͇̿̿/'̿'̿̿̿ ̿ ̿̿ ̿ ̿

٩๏̯͡๏۶

#### Mr. Scientist

• Neilep Level Member
• 1451
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #8 on: 01/11/2009 15:45:03 »
I knew i was right. I came across this convo on the net:

If these particles are attracted to one another, shouldn't electrons be pulled into the nucleus? I gather the reasoning is because of the strong force? If thats the case i need to understand this "strong force" better..

Mizzuno

This question is actually addressed in the Feynmann lectures, which are linked to in the physics napster thread in the General Physics forum. The answer is:

What keeps the electrons from simply falling in? [The uncertainty principle]: If they were in the nucleus, we would know their position precisely, which would require them to have a very large, but uncertain, momentum, i.e., a very large kinetic energy. This would cause them to break away from the nucleus. They make a compromise: they leave themselves a little room for this uncertainty and then jiggle with a certain amount of minimum motion in accordance with this rule.

It wasn't really the answer I was expecting. I was previously under the impression that the uncertainty relations were only an expression of our own limitation as subjective observers of a subatomic event, but apparently they are actually an expression of a fundamental principle governing the behavior of small particles. If you're curious, the relation used here is:

\Delta x \Delta \rho \geq \frac{h}{2\pi}

Where
x = the position of the particle,
\rho = the momentum of the particle, and
h = Planck's constant
[\i][\b]

''God could not have had much time on His hands when he formed the Planck Lengths.''

̿ ̿ ̿ ̿̿'\̵͇̿̿\=(●̪•)=/̵͇̿̿/'̿'̿̿̿ ̿ ̿̿ ̿ ̿

٩๏̯͡๏۶

#### Vern

• Neilep Level Member
• 2072
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #9 on: 01/11/2009 16:49:00 »
If you like to think that Quantum theory represents reality you have to invent excuses. Quarks can not exist outside nuclei, for example. Electrons dance to the uncertainty tune, etc. To me it is much easier just to accept reality as it presents itself.

#### Mr. Scientist

• Neilep Level Member
• 1451
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #10 on: 01/11/2009 16:55:29 »
But it seems that we hve experimental evidence for these conclusions. If anything, i think reality has shaped physics for the larger part, not so much intentionally the other the way.

''God could not have had much time on His hands when he formed the Planck Lengths.''

̿ ̿ ̿ ̿̿'\̵͇̿̿\=(●̪•)=/̵͇̿̿/'̿'̿̿̿ ̿ ̿̿ ̿ ̿

٩๏̯͡๏۶

#### Vern

• Neilep Level Member
• 2072
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #11 on: 01/11/2009 18:13:39 »
Quote from: Mr. Scientist
But it seems that we hve experimental evidence for these conclusions.
But we really don't. I started looking for experimental evidence for wave function collapse years ago. I'm still looking. None found. We have a habit of reporting our conclusions as experimental results. Sometimes it is hard to find the actual results that led the experimenters to their reported conclusions.

In every case where I have searched out the actual experiment the evidence was not there. The POS thought experiment Einstein and company proposed is still valid.

#### Mr. Scientist

• Neilep Level Member
• 1451
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #12 on: 01/11/2009 18:21:56 »
We can measure decoherence, which is the gradual collapse of the wave function in wave-states of matter. We may not be able to directly observe the transformation because in doing so we disturb the p-field ''probability-field''. But, we know the collapse must occur as an actual transition from having matter acts as waves and then suddenly not.

''God could not have had much time on His hands when he formed the Planck Lengths.''

̿ ̿ ̿ ̿̿'\̵͇̿̿\=(●̪•)=/̵͇̿̿/'̿'̿̿̿ ̿ ̿̿ ̿ ̿

٩๏̯͡๏۶

#### Vern

• Neilep Level Member
• 2072
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #13 on: 01/11/2009 18:35:25 »
Quote from: Mr. Scientist
But, we know the collapse must occur as an actual transition from having matter acts as waves and then suddenly not.
But this is what we don't know; this is the idea in contention. Does the observed state happen at the time of observation as in wave function collapse, or does the observed state happen at the time of creation of the particles, as in the POS experiment?

#### Mr. Scientist

• Neilep Level Member
• 1451
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #14 on: 01/11/2009 18:38:08 »
But there is very little else that can happen. Given the intantaneous change from wave to particle-nature means that there is little room other than to say there is a sudden collapse. All models have agreed with observation.

''God could not have had much time on His hands when he formed the Planck Lengths.''

̿ ̿ ̿ ̿̿'\̵͇̿̿\=(●̪•)=/̵͇̿̿/'̿'̿̿̿ ̿ ̿̿ ̿ ̿

٩๏̯͡๏۶

#### Vern

• Neilep Level Member
• 2072
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #15 on: 01/11/2009 18:56:47 »
We don't know that there is an instantaneous transition from wave to particle. We know that there is an instantaneous transition of a previously unknown state to a known state at the time of observation. We have not yet figured out how to know the state of the previously unknown state.

In the simple case of a photon striking a target, my speculative model has changing fields driving two points of maxima of the fields. Interaction always occurs very close to the points of maxima; the fields determine the trajectory.

Edit: Bolded text was edited for clarification.
« Last Edit: 01/11/2009 19:03:41 by Vern »

#### Mr. Scientist

• Neilep Level Member
• 1451
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #16 on: 01/11/2009 19:00:32 »
Though, we have what we need to know about this state, and that is it acts in every way like a particle when its not being observed.

''God could not have had much time on His hands when he formed the Planck Lengths.''

̿ ̿ ̿ ̿̿'\̵͇̿̿\=(●̪•)=/̵͇̿̿/'̿'̿̿̿ ̿ ̿̿ ̿ ̿

٩๏̯͡๏۶

#### Vern

• Neilep Level Member
• 2072
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #17 on: 01/11/2009 19:06:28 »
I can't argue with the success of Quantum theory. It is the only theory I know that demands a change in reality when reality does not agree with it. []

#### Mr. Scientist

• Neilep Level Member
• 1451
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #18 on: 01/11/2009 19:14:39 »
I meant a wave by the way in the passage above - oops.

''God could not have had much time on His hands when he formed the Planck Lengths.''

̿ ̿ ̿ ̿̿'\̵͇̿̿\=(●̪•)=/̵͇̿̿/'̿'̿̿̿ ̿ ̿̿ ̿ ̿

٩๏̯͡๏۶

#### Vern

• Neilep Level Member
• 2072
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #19 on: 02/11/2009 12:02:19 »
I don't mean to be contrary. [] I just need to explore every possibility that might offer experimental evidence that my vision of a photon is not reality. As far as I can determine the double slit experiment supports the vision. If I did not have the photon defined so that it must produce the observed results by cause and effect, I might fantasize some magical wave-particle duality.

The anatomy of a photon: A photon consists of two half cycles of electric and magnetic fields that drive points of maxima through space. The fields exist in a spatial area around the points. The changing amplitude of the fields drive the points and determine their path through space. Photon interaction happens at the points of maxima. So any observation will see the points. Edit: It is not my definition; it is Maxwell's definition.

What perplexes me is that folks don't seem to understand that. Is it that I just can't put the right words together?

Here's a schematic of the vision. It looks just like those that were in the text books when I studied electronics and nuclear instrumentation back in the 50's.

« Last Edit: 02/11/2009 12:18:41 by Vern »

#### Mr. Scientist

• Neilep Level Member
• 1451
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #20 on: 02/11/2009 12:13:23 »
I wouldn't be as bold as to suggest you cannot explain physics, if indeed it is the correct description of a photon. Physics is not easy to explain, whether it being a pet-theory or not.

''God could not have had much time on His hands when he formed the Planck Lengths.''

̿ ̿ ̿ ̿̿'\̵͇̿̿\=(●̪•)=/̵͇̿̿/'̿'̿̿̿ ̿ ̿̿ ̿ ̿

٩๏̯͡๏۶

#### Vern

• Neilep Level Member
• 2072
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #21 on: 02/11/2009 16:51:24 »
I have to keep reminding myself what my goal is here in this forum. It is not to point out weaknesses in Quantum theory, and it is not to promote my pet concepts. It is simply to remind folks when common misconceptions are promoted. In this case it was the misconception that there is experimental evidence that quantum states occur at observation time. []

#### Mr. Scientist

• Neilep Level Member
• 1451
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #22 on: 03/11/2009 16:13:03 »
Fair do's.

''God could not have had much time on His hands when he formed the Planck Lengths.''

̿ ̿ ̿ ̿̿'\̵͇̿̿\=(●̪•)=/̵͇̿̿/'̿'̿̿̿ ̿ ̿̿ ̿ ̿

٩๏̯͡๏۶

#### Vern

• Neilep Level Member
• 2072
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #23 on: 03/11/2009 17:14:01 »
It would really be interesting if there was experimental evidence; maybe a last instant change in one of the states that is reflected in the other. I know that has been tried. All the attempts I know about failed.

#### litespeed

• Sr. Member
• 419
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #24 on: 03/11/2009 19:41:45 »
Vern - You wrote: "There is a cause for quantum phenomena just as there is a cause for uncertainty."

I agree. SOMETHING caused an individual Uranium atom to decay. We just do not know what the hell it is. Perhaps it is a simply some sort of harmonic in the electron field that works a bit like "The Buterfly" effect.

Personally, I have become increasingly convinced our four dimensional world is entangled with one, or probably several other "Dimensions". In our universe NOTHING transits from point A to point B through an infinite number of points. I am unaware of ANY motion that does not pop in and out of our universe according to the various Plank Units.

Perhaps our universe has time movement, but not particle movement. As time progresses paricles move in and out of a timeless 'holding' dimension producing an effect something like a motion picture.

#### litespeed

• Sr. Member
• 419
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #25 on: 03/11/2009 19:55:35 »
Vern

I have a couple of observations concerning Quantum Mechanics that may or may not be relevant.  First, the Drake Equation shows that entangled particles are not a local phenomena.  That means that entangled particle A and entangled particle B do not change polarity symultaneously because they were both 'programed' at the time of separation.

I see no possible way to explain this other then to accept some sort of extra dimensional involvement, that theoretically could communicate faster the the speed of light. I send a series of entangled particles in your direction, followed by a similar sequence of non entagle particles. You notice the diference, and work out some sort of Morse code with the senders. Almost instantaneously you have joined a universeal communications exchange.  Of course the signal SENT to you travels at light speed. The subsequent communications is instantaneous.

#### Vern

• Neilep Level Member
• 2072
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #26 on: 03/11/2009 19:56:14 »
Quote from: litespeed
Personally, I have become increasingly convinced our four dimensional world is entangled with one, or probably several other "Dimensions". In our universe NOTHING transits from point A to point B through an infinite number of points. I am unaware of ANY motion that does not pop in and out of our universe according to the various Plank Units.

I think you're making a huge assumption here. I know of no experimental evidence that movement is quantized.

#### Vern

• Neilep Level Member
• 2072
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #27 on: 03/11/2009 19:59:58 »
Quote from: litespeed
I see no possible way to explain this other then to accept some sort of extra dimensional involvement, that theoretically could communicate faster the the speed of light. I send a series of entangled particles in your direction, followed by a similar sequence of non entagle particles. You notice the diference, and work out some sort of Morse code with the senders. Almost instantaneously you have joined a universeal communications exchange.  Of course the signal SENT to you travels at light speed. The subsequent communications is instantaneous.

I have seen several attempts to show that this could happen. As far as I know they have all failed. I have never seen a proof for wave function collapse in the Copenhagen sense.

#### litespeed

• Sr. Member
• 419
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #28 on: 03/11/2009 20:03:29 »
Vern,

I agree it is a big leap. Howver, the Heisenberg Uncertanty priciple seems to support the notion. Further, I would like your discussion on Plank Units. IMHO, these seem to support a kind of granularity in our universe.  For instance, there is a minimum distance between A and B that can not be subdevided.  Similarly, Plank time seems to support a minimum unit of time that can not be subdevided.

Of course my understanding of Plank Units is very likely flawed.  However, I have actually seen explanations of the Big Bang that include things like Plank Zero is null, Plank Two is such and such proportion of the inflation etc etc.

My basic point is that it seems to me nothing in our universe EVER moves. It simply moves in and out of time.  Just me rambling....

#### Vern

• Neilep Level Member
• 2072
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #29 on: 03/11/2009 21:42:16 »
I have not yet signed on to quantum units other than the quantum of light. That is because I have a speculative cause for How Come The Quantum that assigns the cause to a property of the photon. I guess when you dwell on a subject for a long time it kinda sets in your mind and makes it difficult to contemplate another scenario for the action in mind.

Quantum Phenomena:
How come the quantum then is because empty space has limits on the amount of electric and magnetic amplitude it can support. These limits cause Planck's constant. These limits therefore cause the quantum nature of the universe. We have not invented anything new for this realization. We just noticed the obvious cause for a well known effect. But we only noticed it because we looked for a cause for the quantum effect.

#### thedoc

• Sr. Member
• 513
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #30 on: 04/11/2009 11:50:44 »

#### Jarek Duda

• Full Member
• 70
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #31 on: 02/02/2013 17:03:46 »
Heisenberg uncertainty principle restricts measurement capabilities, not what objectively happens there - I completely disagree with such explanation by eye shutting ...
Quantum phenomenas are much more subtle (like interference), for example we can make expansion around extremely small Planck's constant (semiclassical WKB approximation) and in zeroth order we start with the classical mechanics.
So there should be already a classical explanation of such brutal property like not falling against Coulomb attraction ... and indeed there is - it is enough to remind that electron is not only a charge, but has also very strong magnetic dipole moment - is tiny magnet. So if they would try to fall into each other, while placing reference frame in the electron, proton/nucleus is moving in magnetic field of electron - there appears perpendicular Lorentz force bending the trajectory, so even classically they would have to miss each other.

The complete Lagrangian including electron's magnetic dipole moment ($$\mu$$) looks like that ( http://en.wikipedia.org/wiki/Free-fall_atomic_model ):
$$L = \frac{v^2}{2}+\frac{Ze^2}{r}+\frac{Ze}{c}\left[ v\cdot\left( \frac{\mu\times r}{r^3}\right)\right]$$
« Last Edit: 02/02/2013 17:31:56 by Jarek Duda »

#### yor_on

• Naked Science Forum GOD!
• 12188
• (Ah, yes:) *a table is always good to hide under*
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #32 on: 02/02/2013 20:01:56 »
Yeah, reading it I agree with homely physicist. You can't ignore the Pauli exclusion principle as that is what defined matter macroscopically. Although the Heisenberg exclusion principle is also important, but there depending on how far you want to take it. As a way of thinking or as a real property of the universe.
"BOMB DISPOSAL EXPERT. If you see me running, try to keep up."

#### Jarek Duda

• Full Member
• 70
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #33 on: 02/02/2013 20:29:15 »
Schrodigner picture represents complex electron dynamics as a simple wavefunction - Pauli exclusion principle only says that there cannot be multiple repelling particles in the same dynamical state.
This principle doesn't need to be artificially included - it is already there in Schrodinger equation alone: if we don't treat electrons independently, but include their interaction - use $$\psi(x,y)$$ with repulsive potential, such two-electron wavefuntion has to vanish on diagonal: when potential goes to infinity.
And this principle doesn't work for attracting particles, like electron-positon pair would just annihilate ... we cannot use Pauli principle in proton-electron case.

The Heisenberg principle, on the other hand, says that measurements influence the system - affect eventual additional measurements of noncommuting observables - it concerns only extremely subtle category of phenomenas: measurements (projections - not unitary!).
But atom "works" even without measurements - without applying Heisenberg principle ...

Quantum mechanics gave physicists universal answers when they don't understand: "it's quantum", "it's uncertainty" ... but maybe we can search for the real understanding, concrete answers ... understand the underlying dynamics (like in Couder's picture).

#### yor_on

• Naked Science Forum GOD!
• 12188
• (Ah, yes:) *a table is always good to hide under*
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #34 on: 03/02/2013 00:53:54 »
Doesn't matter (ahem:) if they vanish meeting Jarek, well, as i see it
It's about each particle of rest mass craving a unique space-time position, not willingly sharing it with others. There is more to it naturally as with helium4 etc, but that's how I see it from a simplified definition. And without that principle matter should become chaotic as I think, and the chair might become?? (possibly Anti matter or matter, they are still  defined as rest mass, as I understands it.

And yeah, you hit a very delicate point there discussing HUP.

What is a 'observer'?
Does it need consciousness to be defined as such?
Or is it enough with something, interacting with something else?
"BOMB DISPOSAL EXPERT. If you see me running, try to keep up."

#### yor_on

• Naked Science Forum GOD!
• 12188
• (Ah, yes:) *a table is always good to hide under*
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #35 on: 03/02/2013 01:12:10 »
But there are some weird effects to it, thinking of it from the probability of finding a electron in a atom. The electron (in its orbital inside the atom) is from the point of probability 'smeared out' as I understands it. The measurement alone must then be the definition of 'where it is/was'

And that is not the exact same as defining a unique 'place' to/for each particle of rest mass. But macroscopically I find the Pauli exclusion principle to be what keeps us existent.
« Last Edit: 03/02/2013 01:18:33 by yor_on »
"BOMB DISPOSAL EXPERT. If you see me running, try to keep up."

#### evan_au

• Neilep Level Member
• 4246
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #36 on: 03/02/2013 04:49:25 »
The short answer is that a "proton and electron stuck together" does happen, in a neutron.

However, a neutron is unstable, and will break down in about 15 minutes, releasing an electron (beta particle) and proton, plus a ghost-like particle called a neutrino. This decay releases a lot of energy. So, a hydrogen atom (=proton+electron) is much more stable than a isolated neutron.

Neutrons can be stable, if they are combined into an atomic nucleus with protons in the right ratio. In this case, the strong nuclear force provides the binding force to keep the nucleus stable.
• Too many neutrons, and one could decay (releasing an electron, as described above)
• Too few neutrons, and an inner electron can be captured, forming a neutron, just as you asked
• There are other nuclear decay paths too; for more details: http://en.wikipedia.org/wiki/Stable_nuclei

#### Jarek Duda

• Full Member
• 70
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #37 on: 03/02/2013 08:10:42 »
Quote
It's about each particle of rest mass craving a unique space-time position, not willingly sharing it with others. There is more to it naturally as with helium4 etc, but that's how I see it from a simplified definition. And without that principle matter should become chaotic as I think, and the chair might become?? (possibly Anti matter or matter, they are still  defined as rest mass, as I understands it.
But electron and positron do will to share the same position ... while electrons avoid themselves because of Coulomb repulsion itself, and protons similarly.
Just imagine two-electron wavefunction $$\psi(x,y)$$. It is extremely difficult to calculate it so usually they only consider energy corrections, but the wavefunction is also very different from for two noninteracting electrons because of the 1/|x-y| repulsive potential in this 3+3 dimensional space - it has infinite potential barrier on the diagonal: meaning electrons avoid themselves because of repulsion ("exclusion principle").

The only missing is understanding why against Coulomb attraction, electron doesn't fall into proton, but exclusion principle doesn't help for attracting particles (e.g. electron+proton->neutron).
And it doesn't have to - as I have written, it is enough to remember that electron is also relatively strong tiny magnet - it creates Lorentz force while trying to fall into proton - bending trajectory such that it will always miss.

About helium4 superfluid, shouldn't you rather say that they are bosons so these atoms should be all in the same quantum state?
But in fact it is just nonzero volume fluid ...
Quantum "smart sounding phrases" are great when you don't understand but need to say something ... but these are simplifications - bosons doesn't exactly choose the same state, exclusion of repulsive fermions is already there in Schrodinger equation ... we shouldn't be satisfied with such mystical answers, but need to get deeper ...
Quote
And yeah, you hit a very delicate point there discussing HUP.
What is a 'observer'?
Does it need consciousness to be defined as such?
Or is it enough with something, interacting with something else?
But I didn't want to - I have only pointed out that using it to explain why electron doesn't fall into nucleus is a nonsense...
Indeed "conscious?" observer seems to be extremely delicate point ... but he is made of the same atoms governed by the same physics, so extending the system to include him, the problem disappears ... and vanishes completely when we think of the whole universe as the system - the wavefunction of the universe. It no longer has an external observer, exterior to interact with, so there are no longer wavefunction collapses like measurements - we have unique objective unitary evolution.
And so we can consider objective physics to understand why the atom works - without external observers, measurements, Heisenberg principle ...
Quote
But there are some weird effects to it, thinking of it from the probability of finding a electron in a atom. The electron (in its orbital inside the atom) is from the point of probability 'smeared out' as I understands it. The measurement alone must then be the definition of 'where it is/was'.
This smearing tries to forget about the particle part of wave-particle duality. But now we can measure where exactly was the electron before leaving the orbital - here is such picture made by averaging positions of many single electrons:

So physically the electron was somewhere in the orbital in the moment of being stripped off - remain both wave and particle like Couder's droplets and wavefunction describes only its averaged position density and relative phases of its wave nature.
Quote
The short answer is that a "proton and electron stuck together" does happen, in a neutron.
Indeed ... and Pauli exclusion principle doesn't prevent such sticking together of two parts of matter
However, as you have written, because of strong interaction this state has much higher energy ... so what ground state hydrogen atom is, is just the lowest energetic state of electron-proton pair (excluding proton decay): electron cannot fall into the nucleus just because it would increase energy.
« Last Edit: 03/02/2013 08:13:43 by Jarek Duda »

#### lightarrow

• Neilep Level Member
• 4586
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #38 on: 03/02/2013 14:19:09 »
Part of the hydrogen electron's life *is* lived in the nucleus: its wavefunction square modulus is non-zero there; it has even the greatest value, there!
Infact |$$\psi$$|2 goes as e-r where r is the electron distance from the nucleus' centre.

For example, look for R(r) here:
http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/hydwf.html

and look at the first picture here:
http://users.aber.ac.uk/ruw/teach/237/shape.php
<<The radial solutions of the Schrödinger equation of the hydrogen atom, R(r), are plotted on the right. Each time the quantum number n increases, an additional node is created. At n=1, the radial function is all positive. Its maximum is at r=0, i.e. the point in space with the highest probability density of finding the electron is actually inside the nucleus! That is why the term probability density is used: As we move outward along the radius, the volume of a shell of equal thickness is getting larger and larger, thereby spreading out the probability over a larger volume. >>
« Last Edit: 03/02/2013 14:24:48 by lightarrow »

#### Jarek Duda

• Full Member
• 70
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #39 on: 03/02/2013 15:21:12 »
Indeed the simplest Schrodinger equation leads to that the maximum of electron density is exactly where the proton is ... but this model is just one point charge in potential of another fixed point charge - greatly simplifies the real physics. In the real world electron being in the same place as proton would mean that they create neutron, but it would require relatively huge energy: 782keV.  So including strong force holding baryons together would rather remove this density maximum from the Schrödinger's ground state.

This simplest Schrödinger picture misses much more, like magnetic dipole moments, relativistic corrections, interaction with environment ... it is rather surprising that it works so well, especially as Nuclear shell model where they model this unbelievably complex internal structure of large nucleus with just a simple potential well.
Connecting with independence of environment behavior, which should be seen as thermal noise, we see how unbelievably strong this universality of Schrödinger's ground state is ...

... and indeed it should be - if we make "classical" thermodynamical considerations of corpuscular entities, it turns out that models based on the fundamental in statistical physics: maximal uncertainty principle - Maximal Entropy Random Walk, in opposite to standard "generic random walk" only approximating this principle, also leads to stationary probability density being exactly squares of coordinates of dominant eigenvector of corresponding Hamiltonian: the quantum ground state. Here is comparison of such "classical"(approximated) and "quantum"(corrected) random walks on defected lattice - the second has strong (Anderson's) localization properties:
« Last Edit: 03/02/2013 15:25:05 by Jarek Duda »

#### yor_on

• Naked Science Forum GOD!
• 12188
• (Ah, yes:) *a table is always good to hide under*
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #40 on: 03/02/2013 15:32:43 »
Be that how it might Jarek, but your question about measurements is one that has been on my mind too, but in the form of 'observers', and of course 'consciousness'. And it is important to define it I think. My own view of it is that as long as you define a 'observer' as 'something' being in a interaction with 'something else' the Copenhagen interpretation makes sense, and HUp seems then to be a sort of ultimate answer on the very small plane. If you on the other hand define it such as a 'measurement' always must involve something conscious, deciding to make that measurement? Then all of your objections hold water to me.
"BOMB DISPOSAL EXPERT. If you see me running, try to keep up."

#### yor_on

• Naked Science Forum GOD!
• 12188
• (Ah, yes:) *a table is always good to hide under*
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #41 on: 03/02/2013 16:06:44 »
As for bosons and fermions?

Helium 4 has a rest mass, but is defined as a boson according to Bose-Einstein statistics. Its nucleus has a atomic mass (u) of 4.0026 u. That makes it a member of the Pauli exclusion principle at normal temperatures as I understand, although acting (much) as a boson when as a condensate. The definition of a boson is hinging on the spin, and there the physics differ between a even (bosons) or uneven (fermions) amount of 'spins', counted up all together (net nuclear spin + electrons spin etc etc)  for whatever atom/particle under discussion, defining how the particle will act, as a boson, or as a fermion following Fermi-Dirac theory. But there are differences to 'bosons' too, or you might otherwise be able to expect helium4 to be massless, time less, and move at 'c'
« Last Edit: 03/02/2013 16:24:21 by yor_on »
"BOMB DISPOSAL EXPERT. If you see me running, try to keep up."

#### Jarek Duda

• Full Member
• 70
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #42 on: 03/02/2013 16:43:00 »
The need of consciousness of observer makes it extremely mystical ...
I think the best experiment to understand measurements is the Stern-Gerlach - it doesn't need any consciousness and we can get intuitions classically.
So imagine a particle with a randomly chosen direction of spin goes through such conditions (gradient of magnetic field) making it align in a line: to have spin up or down. The nearest to "up" the initial spin was, the larger probability - so this is measurement for "Pauli z matrix" observable - with two eigenvectors: spin up or down.
This measurement definitely modify the state: from a random one into one of two ... placing a few of them in different directions behaves accordingly to their order as Pauli matrices don't commute ...
Anyway, while we used to see them as something basic, measurements are physically quite subtle and complex phenomenas ...

Ok, let us look also at conscious observer situation - e.g. Schrödinger's cat.
So imagine there is a cat killed by practically random incident like nuclear decay and two observers: one near the cat, and the other separated - for simplicity let us imagine he is spatially separated, like a light year away.
Now after accidentally killing the cat, he will immediately become dead for the knowledge of nearby observer ... but for the knowledge of far observer, he will be in superposition of life and death ...
It seems there is a conflict here - while objectively cat is dead xor alive, it looks like these two observers use different quantum mechanics ... suggesting that QM only represents their knowledge ...
In fact accordingly to QM of far observer, the situation is rather:
(|cat is dead, near observer knows that cat is dead> + |cat is alive, near observer knows that cat is alive>)/sqrt(2)
so the atoms building the "conscious observer" becomes just part of physics around the cat ...

----------------------
About superfluid helium4 - indeed it is seen as made of bosons because of even multiplicity of 1/2 spin, but being all in the same quantum state is huge approximation here as it is just a liquid which can have practically any volume - liquid of electromagnetically binded alphas and electrons loosing the viscosity.
The situation is better for not composed bosons like photons, what is used in lasers for stimulated deexcitation ... but the essence here is to understand why the presence of photons makes it easier to release energy from excited atoms - understand their internal dynamics instead of just saying that photons are bosons ...
« Last Edit: 03/02/2013 16:56:22 by Jarek Duda »

#### lightarrow

• Neilep Level Member
• 4586
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #43 on: 03/02/2013 22:12:03 »
Indeed the simplest Schrodinger equation leads to that the maximum of electron density is exactly where the proton is ... but this model is just one point charge in potential of another fixed point charge - greatly simplifies the real physics. In the real world electron being in the same place as proton would mean that they create neutron, but it would require relatively huge energy: 782keV.  So including strong force holding baryons together would rather remove this density maximum from the Schrödinger's ground state.

This simplest Schrödinger picture misses much more, like magnetic dipole moments, relativistic corrections, interaction with environment ... it is rather surprising that it works so well, especially as Nuclear shell model where they model this unbelievably complex internal structure of large nucleus with just a simple potential well.
Connecting with independence of environment behavior, which should be seen as thermal noise, we see how unbelievably strong this universality of Schrödinger's ground state is ...

... and indeed it should be - if we make "classical" thermodynamical considerations of corpuscular entities, it turns out that models based on the fundamental in statistical physics: maximal uncertainty principle - Maximal Entropy Random Walk, in opposite to standard "generic random walk" only approximating this principle, also leads to stationary probability density being exactly squares of coordinates of dominant eigenvector of corresponding Hamiltonian: the quantum ground state. Here is comparison of such "classical"(approximated) and "quantum"(corrected) random walks on defected lattice - the second has strong (Anderson's) localization properties:

I have to admit to have understood nothing of what you have written, maybe it's outside of my knowledge possibilities.
Just for the news, you are the same J.Duda of the Phys. Rev. article you linked and of this: http://arxiv.org/abs/0910.2724 ?

#### Jarek Duda

• Full Member
• 70
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #44 on: 03/02/2013 22:38:26 »
What you don't understand? I have only pointed out that this density maximum in the center is a nonsense from the point of particle physics (binding proton with electron would cost m_n-m_p-m_e=782keV). This simple Schrödinger equation ignores much more physical aspects, but still gives impressively good agreement, even in nuclear shell model - it is because the quantum ground state is something extremely universal, also from thermodynamical point of view as Maximal Entropy Random Walk shows (these papers and my last PhD thesis was about) ...

#### yor_on

• Naked Science Forum GOD!
• 12188
• (Ah, yes:) *a table is always good to hide under*
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #45 on: 04/02/2013 01:36:22 »
Jarek, what lightarrow mean is that you have had a long hard thinking about this, with friends presumably. We are new to the subject, and it might well be that we miss what you consider obvious. You keep coming back to the quantum ground state btw, can you expand on how you see that? One universal ground state, is that what you mean? And yes, spin states are a mystery to me How they can define matter from 'bosons'. So does your model simplify it, or explain them?
=

This random walk you're describing, would that then be a mechanism that we can foresee? It's what sets the spin states, if I get you right? But it would still be governed by probability, or are you saying that your model give us a tool for a 'classical explanation' that is predictable?
=

I'm probably jumping to conclusions here, but there is one more thing that intrigue me with your ideas. You refer to particles as possibly having 'internal clocks'. If I now assume that a particle, not atom, but let's say a electron can't be split in more parts, what does a internal clock means? That the arrow becomes a 'force' of sorts too? It seems to me that if I assumed a intrinsic time keeping for particles I also lift up time as a real 'dimension'?
« Last Edit: 04/02/2013 03:16:06 by yor_on »
"BOMB DISPOSAL EXPERT. If you see me running, try to keep up."

#### lightarrow

• Neilep Level Member
• 4586
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #46 on: 04/02/2013 20:27:45 »
What you don't understand? I have only pointed out that this density maximum in the center is a nonsense from the point of particle physics (binding proton with electron would cost m_n-m_p-m_e=782keV). This simple Schrödinger equation ignores much more physical aspects, but still gives impressively good agreement, even in nuclear shell model - it is because the quantum ground state is something extremely universal,
...and this is quite simple to understand.
Quote
also from thermodynamical point of view as Maximal Entropy Random Walk shows (these papers and my last PhD thesis was about) ...
...and this is the less simple part  []

#### Jarek Duda

• Full Member
• 70
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #47 on: 04/02/2013 21:08:19 »
Probability density of the quantum ground state is universal from QM point of view because other states are excited - have higher energy and so want to release this energy, deexcitating down to the ground state - so this is kind of thermal equilibrium state (in 0K).
Stochastic models also predict some probability densities for these situations, but standard models predict different from QM (much weaker localization properties). Maximal Entropy Random Walks(MERW) allows to understand this conflict - it is because standard models only approximate the basic for thermodynamics: maximal uncertainty principle. If we do it right, there is no longer conflict - MERW also leads exactly to the ground state probability density.
It also gives natural intuition of the Born rules that probability is square of amplitude (leading to violation of Bell inequalities): in this model amplitude is probability on the end of past and simultaneously on the beginning of future - to get real probability in given moment we have to multiply them. This "fourdimensional understanding" allows also to get intuitive understanding of why quantum computers are stronger than classical: because they can "mount" qbit trajectories in both past (initialization) and future (measurements). Here is schematic picture of Shor's algoritm (description):

Quote
This random walk you're describing, would that then be a mechanism that we can foresee? It's what sets the spin states, if I get you right? But it would still be governed by probability, or are you saying that your model give us a tool for a 'classical explanation' that is predictable?
MERW is thermodynamical model, that means predicting the most probable evolution. It is obtained for the maximal uncertainty principle, what basically means that if there is no reason to emphasize any scenario, we should assume uniform probability distribution. So it is not about foreseeing some concrete scenario, but operating on our knowledge - like what stationary probability we should assume, or if we know where it is in one moment, what probability density we should assume after some time (propagator).
These are completely general considerations - spin is something much more subtle (approximately the direction of magnetic dipole moment).

Quote
I'm probably jumping to conclusions here, but there is one more thing that intrigue me with your ideas. You refer to particles as possibly having 'internal clocks'
It's extremely offtopic here ... while there is topic about it, maybe let us take it there - it was de Broglie's idea (see Hestenes paper), and the Couder's droplets give great intuition of such view on wave-particle duality and basic quantum phenomenas from this point of view ...

#### yor_on

• Naked Science Forum GOD!
• 12188
• (Ah, yes:) *a table is always good to hide under*
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #48 on: 05/02/2013 10:27:13 »
So you do this from assuming a even probability 'density' to the universe? "we should assume uniform probability distribution". So I got it all wrong when I wondered if you were trying for a 'classical' (Newtonian?) definition. I will have to read up on the maximal uncertainty principle, it's new to me. As for a uniform probability it makes sense to me, as long as we ignore interactions, if that is how you mean? I'm good at jumping to conclusions And I like new ideas, and yours are new to me.
==

Btw, anything that can simplify or visualize my understanding of quantum logic and their effects, as you seem to imply in the other thread comparing macroscopic systems to quantum effects, are welcome to me

I'm still stuck on the simple experiment where we split a photon in two (down converting its energy) Getting either the 'spooky action at a distance', or 'hidden variable(s)' defining the outcome. Because I see no way identical photons, whose polarization you can't predict (50% chance either way) before the measurement, as proven experimentally, still always result in the other photon 'knowing' which way the polarization was, and setting the opposite polarization.

How would you describe that from your view? Or maybe that is outside the subject?
« Last Edit: 05/02/2013 10:53:59 by yor_on »
"BOMB DISPOSAL EXPERT. If you see me running, try to keep up."

#### Jarek Duda

• Full Member
• 70
##### Re: Why don't an atom's electrons fall into the nucleus and stick to the protons?
« Reply #49 on: 05/02/2013 10:50:14 »
In terms of random walk, one of equivalent formulation of maximal uncertainty principle says that having absolutely no information about what trajectory the object will chose, we should assume uniform probability distribution among all possible paths - it is MERW. Another formulation is by maximizing entropy.
In physics we emphasize some scenarios by assigning them energy - replacing uniform distribution with Boltzmann distribution ... we can also consider multiple particles with interactions between them through potential (in analogous way as in quantum mechanics) ... please at least look at sources like slides before asking further (especially we are offtopic)..