Is Planck's constant the key to understanding a quantum?

[trogan]

The problem is that when I asked you what the action was, you could not give it to me. You stated that the electron and photon have the same "action potential" yet you can not give me what that potential is when I asked. You need to start learning more about these things before you start basing conclusions upon them.

More importantly, how would having the same action dictate that two situations are the same? Going from the definition you reference, energy times time, I could give you the "action" in this sense of a 1 ton car that travels 1 second at 100 km/hr and say that it is the same as the action of a mole of C_60 buckyball traveling at 54 ft/s for 1 hour. What is of interest is how the action relates to physics in general, through its use in Lagrangian physics. If you learned about Lagrangian mechanics then you would easily see the answer to your question.

As for Planck's constant, to me, it really doesn't mean anything of much consequence. It's just a constant, we can always set it to any arbitrary non-zero number depending on our desired system of units. For example, if we were to use natrural units, then c=\hbar=1. The ubiquitious nature of \hbar popping up everywhere makes it rather difficult to describe what it is since it is present in the basic principles of quantum mechanics, like Schroedinger's equation or Feynman's path integral formulation. However, it is of interest that classical mechanics can be recovered by taking the limit of \hbar to zero with the path integral formulation.

Okay, thanks a lot for that. I see where you are coming from. Action Potential was, like oomph, just something I dreamed up but it seemed very evocative and a hell of a lot easier to talk about than Unit of Action of a Quantum of Energy. Plus it had a rest mass connotation as in Potential Energy.

 

[Vanadium 50]

the Quantum Unit of Action (or Planck's Constant) is 6.62606896(33)×10−34 J·s and Joules is a unit of energy.

Joules are a unit of energy. Joules times seconds are not a unit of energy.

Action Potential was, like oomph, just something I dreamed up but it seemed very evocative and a hell of a lot easier to talk about than Unit of Action of a Quantum of Energy. Plus it had a rest mass connotation as in Potential Energy.

And what we are trying to tell you - and it's evidently not sinking in - is that you don't get to "dream up" stuff until you've learned something first.

 

[trogan]

Joules are a unit of energy. Joules times seconds are not a unit of energy..

Fair enough. Do you mean Joules times second (i.e. 1 second) ?

And what we are trying to tell you - and it's evidently not sinking in - is that you don't get to "dream up" stuff until you've learned something first.

I have mea culpa'ed on this in a previous post.

 

[trogan]

Fair enough. Do you mean Joules times second (i.e. 1 second) ?

So, this seems to be saying that the quantum in QP is a quantum of action, not energy. And it therefore seems to me that time always needs to be involved if energy is to be manifested (maybe a better way of putting it is "if energy is to be involved in an interaction"). Where does that leave E=mc2 ? Can anone enlighten me on the flaws in my logic ?

 

[Vanadium 50]

The "flaw in your logic" is that you continue to try and hypothesize first and learn second.

You will make more progress by trying to learn what QM actually says than by posting your own hypotheses and asking us to show you the mistake. (It also is disrespectful of others' time - it says "I am not willing to put the effort into get this right, but want you to put in the effort to find where it's wrong.")

 

[trogan]

The "flaw in your logic" is that you continue to try and hypothesize first and learn second.

You will make more progress by trying to learn what QM actually says than by posting your own hypotheses and asking us to show you the mistake. (It also is disrespectful of others' time - it says "I am not willing to put the effort into get this right, but want you to put in the effort to find where it's wrong.")

I am trying to build up a picture of QP at its most basic. I am having great difficulty (to say the least). As I am pretty intellegent I would guess others are in a similar boat. And it seems obvious that if people don't get the basics right then QP will be difficult for them all the way through.

I never ask a question unless I am completely stumped, as in this case. I always seek to use whatever means I have available to gain understanding before I ask a question. It is not only more satisfying that way, it makes the knowledge gained deeper and more lasting than would otherwise be the case.

I have more questions that I am stumped on:

1. Can anyone tell me what energy times second actually means ? As it is the very basis for QP I would expect that it would be clearly explained in textbooks and elsewhere. I have not found this to be the case.

2. Also, what is frequency in the equation E=hf as it relates to a photon ? I have been told that it is frequency of a photon but this makes no sense at all. Does a photon vibrate (I presume this means move up and down or side to side) ? How can a photon's energy vary if it always travels at the speed of light ? I have seen E=hf as relating to the wave function (i.e. f is the frequency of a wave in a particle's wave function that relates to the energy attribute of the particle) but few explanations I have met seem to take this viewpoint.

 

[Born2bwire]

So, this seems to be saying that the quantum in QP is a quantum of action, not energy. And it therefore seems to me that time always needs to be involved if energy is to be manifested (maybe a better way of putting it is "if energy is to be involved in an interaction"). Where does that leave E=mc2 ? Can anone enlighten me on the flaws in my logic ?

Once again, you need to look up and learn what Lagrangian mechanics, path integral, and the action are if you are going to start asking questions based on assumptions of their character.

 

[trogan]

Once again, you need to look up and learn what Lagrangian mechanics, path integral, and the action are if you are going to start asking questions based on assumptions of their character.

Thanks for your reply. So are saying that I cannot understand the basics of QP without advanced expertise in the areas you mention ?

 

[DaveC426913]

So are saying that I cannot understand the basics of QP without advanced expertise in the areas you mention ?

No, I think what everyone is saying is you cannot draw your own conclusions without advanced expertise in the areas they mention.

 

[trogan]

No, I think what everyone is saying is you cannot draw your own conclusions without advanced expertise in the areas they mention.

My conclusions are definitely not conclusions. They are all questions. I don't have the answers, believe me. It seems to me that I am just stating the obvious but with a twist that is missing from normal explanations of QP.

I am just interested in the basics of QP. As I have received almost zilch in the way of answers to a myriad of questions, I am starting to surmise that even questions on the basics are not answerable. This is a thread where I sarted with what I thought would be a simple question on the standard definition of a Quantum. And it has now run to 4 pages with almost no answers being provided. Something mighty strange is going on although I concede it is not beyond the realms of possibility that people find me objectionable and are not willing to help ! Hopefully not.

 

[trogan]

Once again, you need to look up and learn what Lagrangian mechanics, path integral, and the action are if you are going to start asking questions based on assumptions of their character.

Can you please tell me whether my definition of action in post #1 is correct or not.