BBC Focus Magazine

[Flakkarin]

Ok, so I just watched Prof. Brian Cox's Night with the Stars, and while admitting physics have never been my strongest subject I believe I kept up with most of it.
However, I have a questions about the Pauli exclusion principle - the idea that electrons cannot occupy the same energy level. I understand how this can be true within an atom, but why does it have to be true for all electrons everywhere? I'm referring to the demonstration where he rubbed the diamond to give it more energy, stating that now every electron in the universe had to adjust its energy so that none were the same as the ones in the diamond. What is the proof this has to be true?

[M Paul Lloyd]

As I understood it, and I may well not have, its the maths that proves it through the 'Pauli exclusion principle' , its one of those moments when you have try and accept that they know what they are on about even if it doesn't seem to make any sense.
I have to admit its the one part of Quantum physics that I struggle with, but then I am naturally sceptical about a lot of things.

[The Beige Avenger]

Ok, so I just watched Prof. Brian Cox's Night with the Stars, and while admitting physics have never been my strongest subject I believe I kept up with most of it.
However, I have a questions about the Pauli exclusion principle - the idea that electrons cannot occupy the same energy level. I understand how this can be true within an atom, but why does it have to be true for all electrons everywhere? I'm referring to the demonstration where he rubbed the diamond to give it more energy, stating that now every electron in the universe had to adjust its energy so that none were the same as the ones in the diamond. What is the proof this has to be true?

It could be due to an abstract concept that says all electrons are really only one electron... It's a bit out there.

All electrons in the universe do not change. I never saw the programme so I don't know what he was actually doing.

Electrons cannot occupy the same quantum state with the same energy level. Electrons with the same energy are seen all the time.

[TJ2007]

I watched the programme and he certainly implied that after warming the diamond and changing it's state, then all of the atoms in the universe would realign themselves slightly to satisfy Pauli's principle. Hard to grasp as it implies instantaneous communication which we are told is not possible.

[The Beige Avenger]

I might have to watch it to see what he said... but... he don't half get on my nerves.

[M Paul Lloyd]

Just an observation but I'm not sure that he so much implied TJ2007 but rather he asserted that all the electrons in the universe must realign themselves so as to avoid being on the same energy level.

So I'm left struggling with my usual ignorance to decide that rather than prove the Pauli exclusion principle it shows that it is probably flawed?

[Shadowwolf]

After a brief gander at Wiki on this and all I find is the exclusion being limited to electrons in an atom, not every electron in the verse.

[M Paul Lloyd]

That would make sense Mr.S but Prof Cox definitley said in every atom....

[The Beige Avenger]

From my perspective, it's flawed and probably designed to make people Ooh and Aah.

Perhaps he was meaning either an abstract concept (like the electron itself, still an abstract concept designed to explain something) or that he is simply stating that everything is interconnected and influences each other so if you change something, things around it change, things around them change, things around them change ad infinitum.

[PTFE]

I too had always believed that the exclusion was limited to each atom but then again my last physics lecture was in '80 so don't count on me. Even if the exclusion does apply everywhere, does simply warming the carbon atoms in your hand by a couple of kelvin alter the electons' quantum states?

[M Paul Lloyd]

Hi there PTFE (no flies on you then eh? )

does simply warming the carbon atoms in your hand by a couple of kelvin alter the electrons' quantum states

apparently yes it does, by inducing energy, albeit only a tiny amount, to the atoms elevates the 'level' at which they exist.
Or at least that's my take on it.
I'm still left wondering if this idea of 'all' electrons behaving in synchronized harmony isn't some magnificent wind up to be honest.

I mean photons also display wave and particle properties so does that mean if I slow a photon down all photons react accordingly? I rather doubt it?

[The Beige Avenger]

Electrons occupy specific orbitals around the nucleus. The possible orbitals are essentially defined by the atomic number (no. of protons).

For a biggish atom, there are a good number of electrons existing in their orbitals and within a specific orbital, 2 electrons cannot have the same quantum state... this applies because they have spin = 1/2 (it's a fermion and obeys fermi-dirac statistics) rather than something like a photon that has a spin = 1 (it's a boson and obeys bose-einstein stats so you can squidge heaps of them into the same space)... a slide side note but in a neutron star, the force of gravity is so strong that the electrons stop paying attention to pauli and get squished into the nucleus.

If you add energy (photon) to the atom and it's of a certain wavelength it will hit an electron in orbit and raise its energy; in the quantum world this means raising its momentum by moving it to a higher orbital.

So yeah, if you increase the temperature of something, that implies you increase the energy and thus affecting the electrons within... although temperature is just a measure of kinetic energy of particles in a system.

[...]

i also questioned this in MPLs thread in news & links and yes, it was not implied it was stated that everything in the uni' was thus connected.
ive just sent Graham Southron an email and asked him to ask old coxy to elaborate

[M Paul Lloyd]

And I just linked this to that topic..

Time for my bed I think...

[Flakkarin]

I was talking about this with my brother earlier (my older brother, and therefore the smartest man I know) and he pointed out that atoms share electrons with each other. So the not-the-same-energy idea must apply across all those atoms sharing electrons, and then, why stop there...?
Apparently though, this brings up the problem of information travelling faster than the speed of light - if all electrons everywhere have to shift their energies when a Prof rubs a diamond. And according to Einstein, nothing should travel faster than the speed of light.
Except some neutrinos, obviously

But there was another question I had which my brother could not answer!
Thinking about the demonstration with two people holding either end of a spring and vibrating it - I understand how this demonstrates the placing of energy levels within the bounds of an atom - but what makes those bounds? If one of those men is the nucleus, what determines where the other man is? What forces bound the electrons so that they have to inhabit the energy levels?

[M Paul Lloyd]

Its down to the attraction of opposites Flakkarin, protons in the nucleus attract the electrons and the closer they are together, the stronger that mutual attraction will be, which (I believe) is one of the reasons why large atoms become unstable as electrons are lost and the balance of the atom is compromised.
Trouble is this would not hold the nucleus together as neutrons have no charge (hence the name) so you also have what is called the strong nuclear force that holds the protons and neutrons together around which the electrons 'sort of' orbit, in a wobbly wave-form sort of way, like a tiny electric motor. The energy levels are, as I understand it, determined by the size of the nucleus and the amount of energy that is available, if it is cold they contract and are less reactive with each other, make them hotter and the bonds between the atoms begin to weaken.

[The Beige Avenger]

Electrons are held in place by Electro-Magnetic forces; the positive charges from the proton attracting them and the negative charges from the electrons repelling. The relationships for how charged things interact were deduced by a chap called Charles Coulomb.

All forces are mediated by particles, in this case, photons. Photons effectively fire back and forth between the repelling charges like throwing weights from one boat to the other to change their direction.

Inside the nucleus, that which mediates the strong nuclear force is called a gluon.

There was a great scientist called Richard Feynman whose diagrams describe (via graphical abstract) what goes on between interacting particles.

[PTFE]

... and where does the energy come from to move the electrons in the carbon atoms that are not getting warmed by BC's hand? They can't move to lower energy states in their atoms as Pauli should've made sure that those levels are already full.

Have I, as an electronic engineer, reached the point where I should just stay away from quantum theory? It's bad enough that electrons flow the "wrong" way down wires without having to worry about them having an effect on everyone else's' circuits, even those in Faraday-shielded enclosures!

[M Paul Lloyd]

I don't think you have to 'stay away' from quantum theory PTFE but dancing around the outside of it does feel a tad safer don't you agree?

I think the warming of the carbon atoms has to be viewed in terms of energy being transferred from one atom to another as the whole diamond warms. If you then put it in boiling water the atoms, along with the electrons would get even more energetic and if you took something like an oxyacetylene flame to it....... in a vacuum to prevent the thing burning obviously..... and heated it to about 2,700 degrees C you could excite those atoms so much that the thing would actually start to melt.
Of course the atoms will remain intact no matter how hot they get, they simply have more energy.

Not sure what the electrons in the diamond, or indeed across the universe would do about that, but personally I'm not buying the idea just yet.

Need more data.

[The Beige Avenger]

... and where does the energy come from to move the electrons in the carbon atoms that are not getting warmed by BC's hand? They can't move to lower energy states in their atoms as Pauli should've made sure that those levels are already full.

Have I, as an electronic engineer, reached the point where I should just stay away from quantum theory? It's bad enough that electrons flow the "wrong" way down wires without having to worry about them having an effect on everyone else's' circuits, even those in Faraday-shielded enclosures!

Electrons are constantly absorbing photons; if the photons are of sufficient energy, it will cause electrons to raise an energy level, this usually means that an electron has to drop down; it does so by emitting a photon also.


AFAIK, electrons only flow the "wrong" way because of how we define current (the flow of positive charge)...

Practical electrics in some ways is as complicated... you don't really need to deal with "real world" issues when discussing the theory