[alancalverd]

This is standard physics teaching as far as I am aware

Your awareness is either faulty or not suported by common sense.

Consider a point source of photons. If a particular photon is duplicated in all places in the universe where is can possibly currently exist, then placing a detector anywhere will attract all the photons. Don't look at the sun.

[mxplxxx (OP)]

This is standard physics teaching as far as I am aware

Your awareness is either faulty or not suported by common sense.

Consider a point source of photons. If a particular photon is duplicated in all places in the universe where is can possibly currently exist, then placing a detector anywhere will attract all the photons. Don't look at the sun.

It seems to me common sense in quantum mechanics is often dispensed with. For validation of my assertion, see  http://discovermagazine.com/2005/jun/cover

[alancalverd]

Eddington had a different view. He maintained that the student of physics should be come accustomed to having his common sense violated five times before breakfast, so that if he were to pass through the floor and reappear in the room below he would not consider it a miracle or magic, just a natural event of very small probability. 

And that is why macroscopic stuff seems to stay in one place. Whilst there is a finite probability of any of your atoms being somewhere else, the likelihood of all of you spontaeously materialising on the far side of the moon is of no practical consequence. IIRC a few buckballs have indeed been shown to tunnel through a chemically impermeable barrier.   

[mxplxxx (OP)]

the likelihood of all of you spontaeously materialising on the far side of the moon is of no practical consequence

But the likelihood of uncertainty causing a malfunction in one of our cells , I would imagine, is reasonably high. Which is good from evolution's point of view but not so good from a personal point of view. I would think one of our immune system's main functions is to make sure cells that don't conform to a type are repaired (or disposed of if badly damaged as e.g. in the case of cancer). But what of uncertainty and the type:) Maybe one reason for aging?

[alancalverd]

It's an interesting point. I've lost my lecture slide about the natural rate of DNA transcription errors but it runs into zillions per day. Most are harmless or ineffective but the adjoining "normal" cells have to somehow prevent the defective ones from multiplying. One oddity is the female breast, which may have to change its function several times at (relatively) short notice, so my hypothesis is that it is more tolerant than the rest of the body towards "deviant" behavior and may permit the growth of tumors that would be killed by the immune system if they occurred elsewhere.   

A complete digression, but an interesting one.

[mxplxxx (OP)]

It's an interesting point. I've lost my lecture slide about the natural rate of DNA transcription errors but it runs into zillions per day. Most are harmless or ineffective but the adjoining "normal" cells have to somehow prevent the defective ones from multiplying. One oddity is the female breast, which may have to change its function several times at (relatively) short notice, so my hypothesis is that it is more tolerant than the rest of the body towards "deviant" behavior and may permit the growth of tumors that would be killed by the immune system if they occurred elsewhere.   

A complete digression, but an interesting one.

Makes sense. There is also the fact that the breast may have to switch off at least part of the immune system to enable it to manufacture something that is meant for a different body.

[Bored chemist]

Breast tissue has to grow suddenly. To do so the cells needs to divide a lot faster than usual. They also need to grow quickly in response to a chemical signal.
That more or less primes them for being at greater risk of becoming cancerous.

There is also the fact that the breast may have to switch off at least part of the immune system to enable it to manufacture something that is meant for a different body.

That makes little sense.
Breasts make various things- proteins etc that are
(1) made for a different body, but also
(2) Pretty much identical to the ones that the breast's owner's mother's milk contained.

If someone had a reaction to the proteins they made for their baby, they would have had a reaction to the proteins their mother made for them; and they wouldn't have survived.

[mxplxxx (OP)]

The latest in photon measurement:) https://scienceblog.com/506371/entangling-photons-of-different-colors/?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+scienceblogrssfeed+%28ScienceBlog.com%29

[yor_on]

It sounds simple but it can't be MP, as far as I know it's really hard to entangle with precision.
=

We'll have to wait until those subs really can 'speak' and see if it works.
Although this seems to be carriers expected to run in fibers?
Ah, maybe not, anyway..

yeah, not what I was thinking of.

[mxplxxx (OP)]

Not too sure whether this experiment actually measure the energy of a photon, but it is interesting that a photon can be detected at all without destroying it.
https://www.sciencedaily.com/releases/2007/04/070402122514.htm

[mxplxxx (OP)]

The author of the reference also states that the absorption is instantaneous.

But how can it be instantaneous? Is it possible the photon has attributes that are immediately transferred to the receiving particle, much like an event in a computer program immediately updates the status of an affected object. 

Basically, energy takes time to transfer. How long depends on the power (Energy per second) of the object the energy is being transferred from. Planck's constant h has an aspect of power about it as it relates energy and time. There is no reason, I can see, to believe that a photon does not have power. How much power is given by P=E/t from E=h/t  which is the wave function of the photons's associated EM wave.

[mxplxxx (OP)]

Interestingly, it seem not all photons carry energy. https://phys.org/news/2015-03-photon-afterglow-transmit-transmitting-energy.html.

It would seem that some types of photons transfer state/energy from one object to another and other types of photons transfer information only about events in other objects. Yippee! I don't think computer science has woken up to the difference - but has now:).

[mxplxxx (OP)]

One last try at punching smoke. The ultraviolet catastrophe was solved by Planck introducing h. Otherwise the classical theory would still predict the energy approaching infinity at shorter wavelengths. https://en.m.wikipedia.org/wiki/Ultraviolet_catastrophe

If you still don't understand then there is no hope.

No hope for hordes of us then it would appear. I am far from alone. A heroic search for the meaning and derivation of h (Planck's constant) was in vain until I came across this post https://www.reddit.com/r/askscience/comments/3qxkvf/how_did_planck_calculate_his_constant/.

The youtube channel viascience has a very very goo series on quantum mechanics. I recommend it very highly. see here https://www.youtube.com/watch?v=SCUnoxJ5pho&index=2&list=PL193BC0532FE7B02C for the first video. It and the second explain exactly how Planck came up with quantisation, and in so doing his constant.

A simple explanation is this. Planck was studying light bulbs, and wanted to work out how to get the most light out of a bulb for the least power. To do this, he needed to model how energy moved about. He initially treated it as if energy moved continuously, rather than in little packets like quantum mechanics says.

He made the model in basically the same way you derive integration (area under a curve in calculus) from first principles. In calculus, to find the area under a continuous curve, we divide up the x axis into many small intervals of width h, then find h times the height of the curve at each interval on the x axis to get an area of a rectangle for each, then sum up the rectangles. We mathematically consider what would happen with smaller and smaller intervals (smaller h) to more and more closely approximate the area under the continuous curve, as opposed to the chunked up (quantised) approximate to the curve made out of rectangles. As you shrink h to zero, you approach the continuous case.

Planck modelled the movement of energy in a similar way - imagining that it moved about in small chunks of size h times the wavelength, and he mathematically imagined shrinking h to zero, to make the model represent energy moving continuously, not in chunks.

He applied this model to observed data, but it didn't match. What DID match, however, is if he neglected to shrink his value h to zero. The precise value you limit h to be in order to make it fit the observed data is what we now call Planck's constant - and it still has the symbol h.

It is my guess then that E in E=hf is only an approximation and the longer the wavelength, the more inaccurate E becomes.

While I am about it let me tentatively suggest based on the above that h is in fact Energy (E), not Action. h is actually the area of a rectangle with width t and height energy where energy is the energy being applied at an instant in time (so power maybe?), not total energy. Hooray, no more Action which is such a controversial unit in physics.

[alancalverd]

A very poor analogy, and not at all what Planck did. This is a fine example of what happens if you grab at a model without understanding its limitations (or, in this case, lack of limitation).

He assumed that a hypothetical electrically charged oscillator in a cavity that contained black body radiation could only change its energy in a minimal increment, E, that was proportional to the frequency of its associated electromagnetic wave.

but the size and shape of the hypothetical cavity in Planck's dervation is not quantised. Thus you can generate a continuous spectrum from a theoretical black body, even if a real source may have a few bits missing.

The dimensions  of h are a consequence of its definition. If E is energy [ML²T^-2] and f is frequency [T^-1], then h cannot be energy. The only interesting thing about h is its constancy, which is fairly easy to measure for single photon events from infrared to γ-ray frequencies and neatly predicts the observed black body spectrum down to long wave radiofrequencies.

Despite doing quantum physics for money for over 50 years, I've never encountered any "controversy" about the dimensions of h. Only priests, politicians and philosphers argue about the bloody obvious.

[mxplxxx (OP)]

Despite doing quantum physics for money for over 50 years, I've never encountered any "controversy" about the dimensions of h. Only priests, politicians and philosphers argue about the bloody obvious.

Not h, Action itself. It has undergone several metamorphoses and I am surprised these haven't affected h. h has units of energy times time. It is hard to see how such a bizarre thing can exist. It is more a concept than a physical unit. It is even harder to see how multiplying Action by frequency gives Energy (E). Why not just do the energy times time multiplication and use h = energy. Far less complicated and it doesn't affect the end result.

h as energy means that vastly more people can understand quantum physics. Few people, including I suspect, many physicists understand Action.

[Bored chemist]

While I am about it let me tentatively suggest based on the above that h is in fact Energy (E), not Action.

Why bother to suggest, even tentatively, something that is obviously wrong?

It is my guess then that E in E=hf is only an approximation

Your guess is wrong.

It is hard to see how such a thing can exist.

It's easy for me to see how it exists.
Perhaps this lack of understanding on your part is the root cause of the problem.

[mxplxxx (OP)]

In my travels I have come across Planck's Constant h being referred to as the "Quantum of Action" and is usually simultaneously trotted out as the basis for quantum theory. Give me a quantum of solace please:). As far as I can see, h is not a quantum of anything; it is a slice of an energy/time graph. The basis of quantum theory is the discovery that the energy of a photon/EM wave cycle can only interact as a whole (quantum) object

[seeker3]

All these fifty years of conscious brooding have brought me no nearer to the answer to the question, 'What are light quanta?' Nowadays every Tom, D i c k and Harry thinks he knows it, but he is mistaken. -Albert Einstein

It is important to realize that in physics today, we have no knowledge of what energy is. -Richard P. Feynman

Photoelectric effect theory won Nobel, why the godfather of quantum theory made that quote?

Maybe there is NO photon particle?

[seeker3]

Photoelectric effect theory won a Nobel Prize. But it is questionable.

If photon has momentum, why navy laser weapons have no kinetic impact?

Why light mill does not move in hard vacuum?

Why photons don't slow down and stop in water like bullets? How can photon accelerate from water to air? What is the mechanism?

[Kryptid]

If photon has momentum, why navy laser weapons have no kinetic impact?

They do.