# Thread: Planck constant - the problem of Joule second

1. Planck constant (h) is the proportianility constant between the energy (E) of an atomic oscillator and the frequency (f) of the associated electromagnetic wave.
The relation between energy and frequency was given by the famous equation:

E=hf

The unit of h is expressed in joule seconds (J·s) or (N·m·s) which is quite unusual as it means the product of energy and time, which is difficult to interpret.
The reason for this is that frequency is given by a natural number divided by time (t), so h must be multiplied by time (t) as the product must result energy.

h x t x n/t = E - in units: joule x sec x n/sec = joule

The other problem with Plancks relation is that h refers to energy change (W) so if we divide it by time, we get power (P) not energy.

hn/t = W/ t = P

If we interpret the product of frequency and Plancks constant what it is  that is Power- , we dissolve all problems:

P = hf - here the unit of h is joule.

The meaning of the equation is: higher frequency has higher power instead of higher energy.
To transform power to energy we must multiply it by time.

dE = W = P dt = hf dt

So time becomes a factor of the equation, not a redundant element of unit.

Sandor Fofai  2.

3. The unit of h is expressed in joule seconds (J·s) or (N·m·s) which is quite unusual as it means the product of energy and time, which is difficult to interpret.
You don't need to interpret it; it is just a proportionality factor in the Planck relation.

The other problem with Plancks relation is that h refers to energy change (W)
No it doesn't; it is not referring to anything. It is just a proportionality factor, and a fundamental constant.

The meaning of the equation is: higher frequency has higher power instead of higher energy.
No - see above. The Planck constant has nothing to do with power, or energy change; it is simply the proportionality factor between energy and a given frequency of a photon.

P = hf - here the unit of h is joule.
Ok, this is just silly, and so not right that it isn't even wrong.

dE = W = P dt = hf dt
And this is completely meaningless.

Tell me one thing - why are you guys trying to invent problems where no problems exist ? E=hf is fine just as it is, and the Planck constant is fine as it is as well; it appears in many other contexts as well, and works as it should. See here :

Planck units - Wikipedia, the free encyclopedia  4. MOD NOTE : I don't know what the claim E=P is supposed to be, but I do know that it doesn't belong in the main sections as it is nonsense. I am feeling very generous, so I'll put it into "New Hypothesis" for now, pending some theoretical and experimental support by the OP.  5. Clearly the elephant in the room with the Planck constant is that it doesn't mention planks.

It should therefore be redefined in terms of elephants per square plank.  6. Originally Posted by PhDemon Planck joke:

Why is a spherical electromagnetic wave-front which has been expanding for 5.4×10−44 s not very clever?
Its as thick as two short Plancks

*get's coat*
*Chuckles and moves on to threads which have some science in them*  7. Seriously, what is it lately with people who see "problems" in fundamental things, proceed to redefine stuff, and break mostly all of physics in the process ? Is there an influx of that nonsense of late, or is it just me ?  8. I don't know. Is it more than just ignorance? Is it some sort of mental illness?  9. Originally Posted by Sandor Fofai The unit of ‘h’ is expressed in joule seconds (J·s) or (N·m·s) which is quite unusual as it means the product of energy and time, which is difficult to interpret.
Not really. The Planck constant has the units of action. It is perhaps worthwhile to note that the four-dimensional spacetime volume integral of density is an action, so from a relativistic standpoint, action may be a more natural unit than energy, which is the ordinary three-dimensional volume integral of density. Also noteworthy is that the Planck constant has the same units as angular momentum, though the Planck constant is generally regarded as the quantum of action.  10. Originally Posted by KJW Also noteworthy is that the Planck constant has the same units as angular momentum, though the Planck constant is generally regarded as the quantum of action.
I hadn't noticed that before (this is touching on an area of physics that I have a woefully poor knowledge of). It might have been better if quantum "spin" had been named "action". This would, at a stroke, get rid of a lot of the crank theories involving spinning particles and might relate it better to the path integral.  11. Mocking is surely simpler than to understand a problem. Whatever trivial it may seem nobody could explain the reason of ‘joule second’. Accepting doesn’t mean reasoning

Maybe I wasn’t clear enough. I tried only to show that as Planck ”quantized” the energy, he arranged the unit of his constant to ‘Planck relation’ resulting energy. However in this case - in lay men like me - a question may pop up: if energy is related to time – here by frequency -, why isn’t it power? Why is it more practical to multiply the unit of the constant with time, then to apply the conventional formula?
An example: according to Planck’s relation the 400Thz red light produces less energy in a second than 600Thz blue light, but red light produces more energy in 2 seconds then blue light in one second.
In formulas:
h x 400Thz/1sec < h600Thz/1sec and 2s x h x 400Thz/1s >1s x h600Thz/1s
If ‘h’ is in ‘joule sec’, then the first expressions results Energy(joule), the second results ‘Energy x time’.
If ‘h’ is in Joule, then the first expression results power ( joule/sec), the second result energy (joule).
Which interpretation seems to be more realistic?

The same is the problem with Heisenberg’s formula, which originally described ‘work’ – see Heisenberg’s microscope – later however the missing ‘/dt’ (to match it to ‘h’) turned the equation into ‘uncertainty’ dividing even the leading physicists. This is the importance of units.  12. Originally Posted by Sandor Fofai Mocking is surely simpler than to understand a problem. Whatever trivial it may seem nobody could explain the reason of ‘joule second’. Accepting doesn’t mean reasoning
And verbiage does not mean logic. You have lots of the former, little of the latter.

The problem is quite simple, really. You don't understand something. Fine. An enlightened response would be to then get some understanding. Instead, your response is to assert that all scientists have gotten it wrong. Mocking is to be expected, especially when you demonstrate a strong resistance to learning. If you would show a sincere interest in actually learning, we'd try that instead of mocking.

Maybe I wasn’t clear enough.
No, you were plenty clear enough. Your writing is PureBollocks)tm).

I tried only to show that as Planck ”quantized” the energy, he arranged the unit of his constant to ‘Planck relation’ resulting energy.
I don't even know what you're trying to say here, but it seems that you aren't aware of what Planck actually did. Perhaps you should read Helge Kragh's accounting of how Planck came to "invent" the quantum of action. Google for it.

However in this case - in lay men like me - a question may pop up: if energy is related to time – here by frequency -, why isn’t it power?
For the same reason that gravity is not weight. You are asking the wrong question. Power is certainly associated with energy and time, but it is not either of them. Association does not imply equality. It's that simple. You've invented a false paradox by starting with an illogical implicit premise.

Why is it more practical to multiply the unit of the constant with time, then to apply the conventional formula?
An example: according to Planck’s relation the 400Thz red light produces less energy in a second than 600Thz blue light, but red light produces more energy in 2 seconds then blue light in one second.

In formulas:
h x 400Thz/1sec < h600Thz/1sec and 2s x h x 400Thz/1s >1s x h600Thz/1s
If ‘h’ is in ‘joule sec’, then the first expressions results Energy(joule), the second results ‘Energy x time’.
If ‘h’ is in Joule, then the first expression results power ( joule/sec), the second result energy (joule).
Which interpretation seems to be more realistic? The same is the problem with Heisenberg’s formula, which originally described ‘work’ – see Heisenberg’s microscope – later however the missing ‘/dt’ (to match it to ‘h’) turned the equation into ‘uncertainty’ dividing even the leading physicists. This is the importance of units.
It's ironic that you allude to the importance of units while displaying total ignorance of what they mean.

It's straightforward. The energy of a photon is proportional to frequency. Multiplied by the number of photons, one obtains the total energy. If you are interested in power, that is a measure of the total energy delivered (or "consumed") per unit time.

Neither energy nor power is action. You seem to be complaining that they should be somehow equal. They are not. Just as kilowatt-hours is not the same as kilowatts. Or joules.

That's the importance of units. Different units mean different things.

As for uncertainty, you seem again to be making up stuff because you haven't actually learned the history correctly. Uncertainty comes about from the built-in fundamental nature of Fourier transforms. Complementary variables are Fourier transform pairs. A narrow distribution in one variable necessarily implies a broad one in its transform counterpart. No "missing" dt was converted to match it to "h." Heisenberg's matrix mechanics doesn't involve the ad hoc arbitariness as you imply.  13. Originally Posted by Sandor Fofai Whatever trivial it may seem nobody could explain the reason of ‘joule second’.
See posts #3 and #11. If you feel they don't explain it then that suggests you need to learn a little more basic physics.

There is no problem with being ignorant. It is nothing to be ashamed of. We are all ignorant to some extent. It is up to you to learn. If you choose not to, then that is a problem.

Accepting doesn’t mean reasoning
Nothing you have said appears to involve reasoning.  14. Originally Posted by Strange  Originally Posted by KJW Also noteworthy is that the Planck constant has the same units as angular momentum, though the Planck constant is generally regarded as the quantum of action.
It might have been better if quantum "spin" had been named "action".
Spin is angular momentum in a genuine sense. For example, the spin of the electron couples to its orbital angular momentum to produce a total angular momentum. I like to think of the spin of a quantum particle as being analogous to the Kerr blackhole, which also has no "moving parts", and gives rise to effects on the surrounding spacetime that indicate that it does indeed possess angular momentum.  15. Originally Posted by Sandor Fofai If h is in Joule, then the first expression results power ( joule/sec), the second result energy (joule).
Yes, and if pigs had wings that could probably fly. But they don't and they can't. Likewise, h does not have dimensions of Joules.

Which interpretation seems to be more realistic?
The correct one, i.e. E=hf, with h being in Js.

The same is the problem with Heisenbergs formula
There is no problem, except in your own personal opinion, but that doesn't count for much I'm afraid.  Bookmarks
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