B Why Do Objects Move? | Molecule Physics

[sophiecentaur]

Imagine that a single hydrogen atom in my finger/hand comes close to a single hydrogen atom in the block..

That is the problem with your model; it's too simple. A single Hydrogen Atom that's in a block is entirely different from a single, isolated H gaseous atom. The Energy jump from the ground state is in the optical region, which is far too big to achieve with an ordinary collision (high speed electrons or photons will do it but that doesn't apply to the Mechanical situation you are trying to explain). A single H atom in the block (or, more reasonably, several billions of them) can be displaced about equilibrium position by as little as you want because of the band structure of the energies, rather than the discrete energy levels in a gas.
You have ignored my very simple (car suspension) model (not prepared to draw the analogy, perhaps?) and seem to have ignored the previous mention of Energy Bands. Both those ideas are essential to grasp if you want to get anywhere here. Fact is that you could push an individual H atom millions of times and it would accelerate every time. It's "internal energy" (do you mean its Quantum Energy state?) would not change. It would be an Elastic Collision if the energy supplied were less than that required for the first transition. When you push the block, you displace billions of atoms and they will take up new positions during the push. Some of the energy involved will be stored as Potential Energy but some will end up as Phonons, which contribute to the thermal energy. (The proportion will govern the lossiness of the material - coefficient of restitution kind of thing.)
I suggest that you first get to understand the simple mechanical situation and then, if you have to, relate it to the microscopic situation. We all seem to agree that your approach is not fruitful so why not take advice and look at things a different way? It really does make sense. Alternatively, there is no shame in saying "It's too hard guv".

 

[Deepak K Kapur]

@ Sophiecentaur

I think I have not been able to convey myself properly. I DO understand the mechanical situation. I am trying to get at the bottom of it. ( You can even criticize me for being a reductionist out and out)

In your post I can't understand how a single hydrogen atom has discrete energy levels and the same atom in a group has continuous energy levels.

Thanks again for your God-like patience.

 

[sophiecentaur]

In your post I can't understand how a single hydrogen atom has discrete energy levels and the same atom in a group has continuous energy levels.

That's how QM works
In an isolated atom, the equation is very simple and has discrete solutions. In condensed matter, the equation is massive (taking into account interaction with every nearby + and - charge) and the solution comes out as a continuum of levels and, hence a continuum of transitions within bands. It isn't surprising that you can't "understand" it if you have never learned it. It's another bit of QM that just isn't intuitive. Solid state Physics is all about the statistics of huge numbers and you have to fling away the simple Hydrogen atom we all learned for starters.

 

[Deepak K Kapur]

Well, what to say... except

I have FAITH in you and the ways of the universe.

But, people must have done such experiments with Bucky Balls or such heavy molecules to see if the band energies are really continuous.

Any inputs, anybody.

On a lighter side, what you have told me is akin to the following..

An iron ball appears in front of me just from thin air. I do all the possible experiments with it and find no anomaly with its composition, structure etc. I do such experiments daily and find no anomaly. In fact people have been doing experiments with such balls for hundreds of years and have found no anomaly either. The only thing being that the ball vanishes into thin air after an hour.

People say, well THIS IS HOW OUR UNIVERSE REALLY IS.

Thanks again.

 

[sophiecentaur]

But, people must have done such experiments with Bucky Balls or such heavy molecules to see if the band energies are really continuous.

The results of pretty well every experiment that has ever been done have indicated the continuum of energy levels in condensed matter. Your computer relies on it to work. You don't need exotic Buckyballs to show this - except, with the relatively small number of Carbon atoms in a Buckyball, I would imagine that it would be possible to resolve the gaps between levels. You could, perhaps, research this.
But your Philosophical comments are fair enough. I do not believe in ultimate truths. Physics doesn't go for them. Physics has the job of coming up with models (a model) that can predict the outcome of a situation within the limits of possible experimental accuracy and the limits of the conditions that can be produced. The LHC has provided new extreme conditions that allows for new theories and the confirmation of some hypotheses - within the new limits
A ball that disappears as you suggest would certainly produce some head scratching. But we will worry about that when you actually produce that ball. The Universe has proved to be remarkably consistent, so far . . . . . . . . . . . . The band structure of solids is certainly no surprise.

 

[Deepak K Kapur]

What is the underlying reason that the solution in case of solids produces a continuum of levels?

In other words, what is the law that dictates that when many electrons/charged particles/nuclei come together--- the discreteness has to go away.So, surprise is very much there.

 

[sophiecentaur]

What is the underlying reason that the solution in case of solids produces a continuum of levels?

So, surprise is very much there

Do you have any idea about the solution to the Schrodinger wave equation? For a Hydrogen atom, it gives a very limited number of energy levels that the system can occupy. Consider the levels, crudely, as being related to the separation (physically) of an electron (particle) and a Proton (particle), which can only take certain values because of the wavelike nature of the particles. Now consider many more nearby charges - electrons and protons. Each one will contribute to the net energy level of any particular electron - spreading the possible values of the actual levels about what you would have expected for an H atom. That cannot really be surprising. Even adding another H atom to form an H2 molecule alters the levels in both atoms so how much more combinations could you expect with millions of nearby atoms in a solid that are close enough to affect each electron.
Rather than being "surprised" why not read up about it and then you will be less surprised that there are things there that you don't yet know. Physics is full of them - for all of us. Do not rely on what you are reading on this thread. Be an active learner and limit the Q and A method, which is highly inefficient.

 

[Deepak K Kapur]

Not arguing...

Surprise has to be there.

What is the reason for attraction of positive and negative charges that they lead to continuum of bands when present in large numbers ---- a surprise.

If you say conditions in the Big Bang decided/produced positive and negative charges and their attraction ...what is the reason for the Big Bang ---- a big surprise.

You can't do away with surprise

 

[sophiecentaur]

You can't do away with surprise

That's certainly true - but you can avoid a whole lot of surprises if you do your homework.