How Big Are Photons?

Thanks emc_c. Good analogies.

I guess what I'm most curious about is the size of photons. Unlike the radio waves from my favorite station, photons strike a photographic film and leave a dot -- after entering my telescope of limited resolution because of its limited aperture.

The telescope next to mine didn't get the photon at all, implying that the photon is localized. As some form of packet -- a quatum of energy. The photon is here, but not there. Everywhere it is not imputes some sort of size, doesn't it? Some limit on its extent?

Physicists talk about the sizes of atoms, of protons and neutrons. Not electrons as they seem to have no extent at all. They talk about these things, but nobody seems to talk about the size of a photon. They talk about the wavelength, but not the size. Why is that? Don't they know?

I'm not an astronomer, not even amateur, but there is something flawed in your comment about the adjacent telescope not catching the photon that your telescope caught.

It is well known that larger telescopes catch more light and can see farther into space. If the photons from a distant source were so narrowly focused that they would hit one small aperture telescope but not another one next to it, then bigger aperture telescopes would be no more sensitive than small ones.

A conundrum...

On a different tack, you cannot think of a photon as a particle of finite size. Recall my first post about wavicles and wave-particle duality and being careful to remember the difference between models and reality.

Perhaps a better way to think of the size of a photon is as a time duration. If you have a continuous emission of radiation from an extended radiating source, you see a constant level of illumination. But suppose you were able to raise a single electron from a low energy state to a higher state, and then let it fall back to the lower state, during which event it emits a photon of electromagnetic energy equal to the difference of the two energy states. The visual here is of a single frequency burst of light of limited duration. The photon wavefront acts like a wave in terms of interaction with space, but it only lasts for a few nano/pico(?) seconds.

I'm not claiming this is how things work, but I think it is a useful model.

"...photons strike a photographic film and leave a dot ..." - The dot left on the photographic plate are the chemical trace on the 'excited' emulsion, and are not indicative to the size of the photon, which only passed some of it's energy to the emulsion (in older chemical photography, or, to the CCD, in today's digital sensory).

Like electrons, photons have no physical boundary, which is probably why you cannot determine where one ends and the other begins.

It's a bit like the Cheshire Cat:

Where does the smile end and the cat begins ?

Solid matter is an illusion caused by the behaviour of quantum particles, which basically are continuous, fuzzy entities - or in other words - force-fields interacting with each other.

Single photons can be electronically detected, but none as to their size

"Consider that we sent men to the moon and returned them safely to earth,..."

emc_c, I was a huge fan of the space program. I was glued to the set at the slightest mention of space, NASA, Mercury, Gemini, Apollo -- you name it, I watched.

The weirdest thing happened during one of the programs, and I've never figured it out. It really makes me wonder........

One of the Apollo moonshots was about halfway between Earth and the Moon when they broke out their TV camera and showed us Earthlings what our planet looked like from some 150,000 miles out. The Earth was small, mostly in sunlight, almost full. It hung in the black sky outside the window like some Christmas ornament. It was not the Moon, but a distant Earth. The astronaut described it as looking like a beautiful jewel or something along those lines. This is not typically how the Moon is described. It was Earth as you'd probably see it from that far out. Then came the kicker...

The astronaut put the camera in his lap. It was still transmitting video and you could see different parts of the spacecraft interior as the astronaut jostled it about, doing something else. You could see his feet, part of the control panel, an interior light, and so forth. I guess he forgot to turn the camera off.

Then it happened. The camera got jostled around such that it looked out the window on the opposite side of the craft. In this position it should be looking away from Earth toward, possibly, the Moon or just empty space. So you'd think, huh?

The view out the other window was hardly empty. In fact, it was completely filled with a fine view of the Earth from Earth orbit. Got that? Earth orbit. Not an Earth seen from halfway to the Moon, but from a few hundred miles up! You could easily see cloud tops, the sheen from the ocean's surface, and bits of land. You could see the Earth turning beneath the craft just as you'd see it turning from beneath the Space Shuttle, and from roughly the same altitude. It was all very clear, very unmistakably Earth from maybe 100-200 miles up.

So what the hell was that little image of Earth doing in the other window? The Earth that was so far away?

Then the video suddenly cut out and the program went back to a very puzzled Walter Conkrite.

When they replayed the transmission later that last bit of footage had been removed. I never saw it again. Nor was any mention made of this puzzling affair. Not by broadcast television. Not by Walter Conkrite nor anyone else. He seemed pretty somber the rest of the program, like something was troubling him.

This puzzle has always bothered me. A lot. The implications of what it means is tremendously significant. That shot of Earth from 150,000 miles had to be fake. It had to be. There's no other explanation. Even an eighth-grader (me) could smell duplicity in the air. My dad, my brothers and my sister were stunned. We looked at each other in total disbelief.

Earth on one side of the craft seen from "halfway to the Moon," and Earth on the other side of the craft seen from not more than 200 miles up. All during the same five or ten-minute TV transmission. How do you explain that? I'm still at a loss.

From that day on I felt the whole space program was suspect. Things like that just don't happen. Somebody was pulling the wool over our eyes. Me and my family saw this faux pas live, as it was happening.

Somebody was fooling someone. And getting away with it.

Could his camera have been filming the reflection of the earth in the cabin window.

How would that origninal image of the earth have been faked unless taken from 150 K miles away.

Did he perhaps adjust the magnification of the camera lens?

Never saw that, but the answer is obvious. Camera recording function was shut off and what was recorded earlier on the tape was seen, which was shown as the tape continued to run. This is all on the assumption that they used a nascent and primitive video system back then. Makes more sense than a conspiracy. I finish watching a football game I taped and when the recording stops I watch the end of another game I had taped over from the previous weekend on the same tape (because the previous game ran longer).

You may want to present your doubts on a site where wackos will support your claims. They are plentiful.

There was no discontinuity in the transmission. The camera was not shut off, but was running the entire time. It was every bit a live transmission as was the TV coverage of Neil Armstrong's setting foot on the Moon. In the late 1960s live TV coverage from a Moon-bound spacecraft was Big News. There was no tape-splicing, editing or anything along those lines because there wasn't time. It was live.

Doubts are not claims. I'd wager that even you know the difference.

Exactly, TVP45, good answer. Ubernerd was way over the top - Europium framed his question/skepticism in a logical manner, presenting an observation and drawing a possible conclusion at odds with accepted wisdom. And there was even independent, unsolicited corroboration of his observation. I am one of those who thinks/wants to think that the space program was on the up and up, but I don't have a ready answer for him, other than "say it ain't so." The only problem with the original Europium comment is it was off-topic from the original post query about photon "size."

Ubernerd should reserve his fire for the many who post to CR4 about physical impossibilities such as violations of conservation of energy. I repeat my plea to the editors I made in one of those "over-unity" threads:

"Could CR4 maybe have a separate mandatory category for posts which violate fundamental laws of physics? That way those who are interested in the freak show can enjoy themselves, and the rest of us don't need to be bothered. Thanks!"

"

Hello TYP45: good answer.

I find Europiums comment questioning something unusual, extremely fitting considering our topic of discussion on this thread. The key word here is questioning, while I was being sarcastic with my original comment as to the government being a reliable source of information, both by national security necessity, and plain criminal conduct at times, government press has been anything but an accurate source of information.

The basis of all science is questioning, a repeatedly proved theory like relativity is still a theory. Considering fairly recent events of a notable scientists being prohibited from publishing for two years for exaggerating his results on the detriments of electromagnetic radiation, or a doctor /researcher completely faking results on silicone implants, even those trained to question results are prone to take things for granted.

A little questioning and skepticism never hurts. While I personally believe the lunar landings are legitimate, I must the least extend the possibility that they were fake. The comment made by Europium merely questioning an anomaly is nothing more than good science.

Enough of the soapbox, I'm not even sure where I left my shoes last night. I have had suspicions at times of my dryer developing a singularity that swallows a stock from time to time, while being sarcastic anyone that says that that would be impossible had better review quantum mechanics. Anything is possible the probabilities are what count.

Hi, YWROADRUNNER!

Here's another possible explanation for the discrepency in earth-view field size.

While the camera was floating around, a zoom button got pushed and the port it was looking out was actually on the same side...not on the 'other side' of the space craft (difficult to find a port on the other side with the kind of craft used for lunar landing vehicles anyway). The second picture was the zoomed one. Bigger.

Or some such. Whaddya think?

Mark

Hello emc c,

Very good job of explanation Sir. GA to you...........(Even I almost understood!)

Take care...............

Nice.

Hello emc c,

Are you trying to set a record for number of GA's?

If I can I will give you another. (Not sure if I have or not but brilliant post!)

Take care..............

By the way I hear Bill Gates or, the bloke who took over as CEO, is looking for people like you!

Babybear,

Thank you for the kind words. I'm pretty sure Microsoft wouldn't have me - I am happily pecking away at my G5-based Mac desktop computer. It's in the basement of my home, which is my office and museum of antiquated radio test equipment. I am happy here, and I believe my customers are happier with a solely electronic interface to me than face-to-face.

When I am on the road, I use my G4-based Mac laptop - just can't get me on a PC. I spent an hour or more this evening trying to get my wife's PC back to work after having it repaired. I think it's a dead loss, and after a frustrating hour of dealing with Windows, I'm taking it easy and discussing the fundamental laws of the Universe.

Compared to Windows, it's a piece of cake!

Thanks again,

emc_c

Hello emc c,

If you have time, after running the Universe!.........

I am thinking of buying a Mac but:

1) I am not sure how different they are to use compared to a PC?

2) I have not looked into this at all, but am pretty fed up with the constance avalanche of b-ll-hit spam, and infections.What are the infection rates for both you machines? I would bet on nowhere near window!

Your Business sounds very interesting. I am an avid listener to HAM Radio. And have a shortwave FRG7 and a microwave set. But they are both packed away for the moment. I moved some time ago and want to sort out antenna before I think of unpacking.

Thank you for your post by the way.

Take care...................

G A and G means great. The speed of light (and it's wavicle) travels in curves, and thus, "an illusion" because we model in psychics. The shortest distance between two points (in our three dimensions) is a straight line, or your "flat mirror". The ancients must have had an innate "knowledge" of the sun, and "time".

Sorry about the off-topic post, Guest. I submitted my post without thinking to mark it off-topic. My apologies.

No problemo. Pretty interesting post if you must know. I saw that show too, the one with two earths. Never figured that one out............

Hello Guest,

Unfortunately the answer to your question is not quite as simple as, say, asking "how big is a baseball." Photons are quanta, as you said, and such they obey the rules of quantum mechanics. And, as everyone knows, quantum mechanics never play baseball because they're nervous, skittish types who are always uncertain of their aim. They never know when they'll put out someone's window. Even when they're facing the other way.

Probably a more apt question to ask would be, "How long does it take for a photon to be emitted?" At least by asking this question we can estimate an upper bound on the length of a photon. This, too, is unsatisfactory on a number of technical grounds, but has the advantage of being in familiar territory. QM, of course, defies common sense. (That's it's primary mission: to obfuscate reality. Please don't tell anyone because a lot of careers are on the line.)

So how long is a photon, anyway?

To be really safe, the answer has to be infinity. Of course, we see photons emitted all the time and these events happen rather more quickly than that. Of course, this just means that the photon emission time scale is very long compared to some other characteristic length, yet still very short compared to the time scales we are used to. To identify what each of these time scales is, we need to look at how photon emission is observed and how it is theoretically analyzed.

First lets look at how photons appear theoretically. Take Maxwell's equations. They form a system of linear translation-invariant equations. A Fourier transform decouples the fields into independently vibrating modes, each with a characteristic frequency. In this form, quantization is trivial. Each mode is treated as an independent harmonic oscillator. So far so good?

The spectrum of stationary states (those with definite energy) of a harmonic oscillator is well known. It is discrete and equally spaced, with the spacing given by the frequency. Each state is labeled by an integer n. The energy of the state is basically a multiple of this number. We like to say that the state n contains n quanta, each with energy proportional to the frequency of the oscillator. These quanta are called phonons. Each stationary state of the electromagnetic field can be described by a linear superposition of states with definite finite photon number in each vibration mode.

So far we have only described stationary states of the EM field and given them an interpretation in terms of photons. Obviously this does not cover non-stationary states, which describe photon emission, for example. If we know all the stationary states and their energies, we can in principle describe all time dependent states of the EM field as well, but *only* of the EM field. To model interesting physical situations, we have to introduce other matter or fields and interactions with them. Unfortunately, for most interacting systems, we can't write down a closed form solution for its state spectrum.

Calculations are usually done in perturbation theory. The crucial assumption is that we can approximate the state at the beginning and end of the experiment by stationary states of the non-interacting EM field + matter system. The interaction can then be turned on and off in between. By necessity, for the initial and final states to be well approximated by stationary ones, the on/off switching of the interaction must be slow, i.e., adiabatic. That is why we formally place the initial state at time -∞ and the final state at time +∞.

So, with this set up, how do we characterize processes in which photons are emitted? It's rather simple really. Count the photons in the initial state and count the photons in the final state. If the latter
number is larger than the former, then we say that some photons were emitted. Note however, that the only answer we can give to how long it to took for the emission to take place is infinity, which is the elapsed time between the initial and final states.

Okay, now we know what theorists mean whey they speak of photons. How about experimentalists? If you look at the experimental evidence that is pointed to when speaking of photons, it always comes back to quantization of energy, for example the photoelectric effect and Planck's radiation spectrum. But to measure energy we need to observe the system for a sufficiently long time. In other words, the experimental setup is such that the system's state can be approximated by a stationary one. But that's exactly where the theoretical description of photons comes in. Everyone is on the same page here. And it's a wonder, too, because theorists and experimentalists are seldom even in the same room.

Finally, we come to observation of emission. The experimental procedure is to prepare the system in some known state (again most likely approximated by some stationary state), wait for the emission event and for the detector to register the emission (wait for the detector to also settle close to a stationary state). This matches the theoretical description as well. But then we face the same uncertainty about the time needed for emission.

However, now we have at least some bounds the needed time just by the amount of time needed to setup the experiment and wait for the results. With better technology, the time needed to perform the experiment can be shortened. Can this be done until the least upper bound on the emission duration is reached? Here, quantum mechanics says that you can get close, but not quite. If you don't allow enough time for the system to come close to a stationary state, the theoretical approximation and the photon description break down. You will still measure photons absorbed or emitted. But the results of the experiment will become more and more erratic. In other words, the uncertainty in the number of photons absorbed or emitted grows the less time you devote to setup of the experiment and to observation. This is nothing but the energy time uncertainty relation.

So, at the end of this perhaps overly verbose explanation, the simple answer is given by the Heisenberg uncertainty principle. If the energy of the photon is E, the time needed to emit a photon of this energy is greater than hbar/E. The longer you wait, the more sure you are how many quanta were emitted. The less you wait, the less certainty there is about the number of photons emitted, which could also be zero.

Hope this helps. Sorry about the (reply) length. I told you it wouldn't be simple, but even then I wasn't certain.

Hi europium,

That was a long answer. I'd vote a good answer for you, but I'm not certain if it either.

S

Length does not equal good, and I'm not comfortable with it either (to be perfectly honest). Photons are sneaky little devils and we don't really -- not really -- understand them. We have all the standard explanations, of course, but what, actually, is the deeper reality? Seems we know a great deal less about photons than what meets the eye, so to speak. Even less about electrons. Practically nothing at all about mass, and maybe a just tad more about that if the LHC produces a Higgs boson. Maybe.

We've got all these models (with the one above being rather reductionistic I'm afraid), but they're just that -- models. When we speak of a photon, what are we really talking about? A model. Meanwhile the little beasties are whizzing right by our uncomprehending minds. At least our models are halfway useful. But we really don't understand the beasties themselves.

So how long is a photon, anyway?

Or when does one photon stop and another one start?

The incomparable Michael Fowler answers (or fails to answer, depending on your point of view) that question this way,

"It does not correspond to a physical picture readily interpretable in terms of familiar concepts."

And that's the big barrier to grasping QM - it just doesn't make sense. We draw "wavicles" on the whiteboard, but that's not really what it is.

Think for a minute of the familiar sine wave. What we draw is only correct when it goes off to infinity in either direction. If we took just a tiny portion of that sine wave, we would lose the ability to determine it's wavelength; so it is as we try to describe a photon which is a superposition of an infinite number of indeterminate wavelengths.

Not very clear, or satisfying, I suppose. But some (many?) questions become nonsensible in QM. Probably the best way to deal with this is not "either or" but "and" for the wave particle question.

Some good sites to look more closely at this are

http://hyperphysics.phy-astr.gsu.edu/hbase/quacon.html#quacon

http://galileo.phys.virginia.edu/classes/252/Bohr_to_Waves/Bohr_to_Waves.html

http://www.technology.niagarac.on.ca/people/mcsele/lasers/Quantum.htm

Hello Guest,

Part of the issue with size is energy. An IR photon and a UV photon may travel the same speed but UV is/has much more energy. I do not know if this effects gravitational lensing, but if it does then it also changes their mass. If it does not then the additional energy must be something like a spinning top spinning faster.

The difference in energy/frequency is what makes optic lens work. It also causes chromatic aberration.

The wave/particle issue is a quantum effect, even small molecules have been found to act this way.

Brad

HI UV,

Gravitational-lensing has to do with the warping of spacetime by the presence of mass. GL is a special case where a central mass (a massive galaxy or cluster of galaxies) warps spacetime in such a way that light from distance sources behind the mass is bent round to converge on the other side of the mass. You can clearly see in this pic of the Abell cluster how it bends light from very distant galaxies behind the cluster into arcs of light. The brightest object seen in the pic is a supermassive elliptical galaxy and is responsible for most of the gravitational lensing seen here.

The diagram below shows essentially what is happening with GL.

My apologies for the poor resolution. Apparently CR4 doesn't preserve the full resolution of uploaded images, and decimates them. Rescaling scales the decimated image, resulting in graininess when you try to rescale the image after uploading (decimation should be done *after* re-scaling, not before, IMHO):

Photon wavelength and energy is not affected by gravitational lensing so much as is the trajectory of the photon as seen from a distant vantage point (however, from the photon's point of view it has been travelling in a straight line the whole time, except that photons don't experience time).

Also, photons have no rest mass, but they do have mass/energy of the E/c² kind.

Hi europium,

So the ton of feathers and the ton of lead fall at the same speed. Dope.

I think it is bed time. Obviously not firing on all cylinders.

Brad

It's too late in the evening for me to enter into this discussion. I should've never looked at it quantum mechanics drives me to drink.

If we're saying all photons are the same size, the question is how do you judge the size of the photon? How does the information packet in a tunneling photon reach the detector before and not obstructed photon?

How does light go faster than light? I'm only doing this for two reasons, 1. there seems to be some intelligent answers from some smart guys. 2. I am getting revenge for the headache I have trying to digest the answers, and the hangover I'm going to have in the morning.

I leave you with these wise words.

If anybody says he can think about quantum physics without getting giddy, that only shows he has not understood the first thing about them.

Never express yourself more clearly than you are able to think.

No, no, you're not thinking; you're just being logical.

We are all agreed that your theory is crazy. The question which divides us is whether it is crazy enough to have a chance of being correct. My own feeling is that it is not crazy enough

Everything we call real is made of things that cannot be regarded as real.
Niels Bohr
for all quotes.

Somehow that loged me as guest, if I'm going to all the trouble to give everybody a headache I want the credit.

LOL!

One answer might be to look at the coherence. In an interferometer, light will interfere if the path lengths differ by less than a given amount. For a highly coherent source such as a laser, this might be thousands of feet, even if the light is attenuated to the point where only one photon is in the interferometer at a time. This defines the photon length.

The width depends on how collimated the light source is. If you can form an interference pattern with light reflected from mirrors 2 inches apart from a distant star, you could say the photons are 2 inches across. (I've read somewhere that a photon from a distant quasar might be as large as Texas.)

The mystery of Quantum Dynamics is how something that size can make a tiny dot of silver on a piece of photographic film.

This is a question without an answer.

Think of a line - not a very, very thin cylinder but a mathematical line. What is it's width? If it has any value (including zero), then it's a skinny solid, not a line. The definition of a line includes that it has only one dimension (length). So you can't ask a question about the width of a line.

Similarly, with a photon, it's meaningless to ask about size when we're seeing energy (What is the diameter of a Joule?). Size only counts when we're looking at the effects of photons, i.e., interference slits.

Hello TVP45: you said with a photon, it's meaningless to ask about size.

Good idea to take a different approach, in the two slit experiment a single photon will cause an interference pattern if both slits are open, it's Richard Feynman's sum over histories interpretation that the photon takes every possible path in the universe to go through the slit.

T=0 for anything moving at the speed of light. If something is every place in the universe (again time is meaningless) is it infinitely large, and then only becomes measurable when it becomes subject to the effects of time, by being slowed by the photographic paper (or similar detectors) and destroyed.

. Probably not making much sense I'm still nursing a hangover from last night and on my second cup of coffee, if you've ever read about the antics of Richard Feynman, or Bohr, it becomes easy to understand why these guys had a sense of humor that you would normally associate with someone that was one sandwich short of a Picnic.

Bhor failed a physics final by answering the question of how would you measure the height of a building with barometer , saying he would throw it off the roof and see how long it took to hit the ground, Richard Feynman played around opening high-security safes, and did his work at a topless bar.

I am going to go put my cat in the box now and see if her meowing collapses the wave function.

That, my friend, is a hell of a hangover. Ouch, alka-selzter, don't fizz so loud....

Hello TVP45:

If you take their age from the distance they travel, measured in ns, the clever Japanese have made a single photon last 2.2 ns. They made holes if some....................oh, stuff, which were accurate to a nanometer to allow this. I can paste the results if anyone is interested.

I mean, I almost know what I am talking about............does that count?

Take care..............

Hi guest. Maybe your initial question of "How Big Are Photons?" has no meaning at all.

Let's take, for example, the more familiar and tangible electons. How well do we know them??? Do they have physical dimensions or even a size??? Do they have "zero size" (i.e. mathematical point)??? No, as the intensity of their electric field should be "infinite" exactly on them. Do they have "definite size" (i.e. a small sphere)??? No, as their distributed charge should disolve their structure (repulsion forces). So, we don't have a clue of "how they look like"... We can't be even sure "exactly where are they" at a specific time instant. We can only know the possibility to be "inside a space area" thanks to Quantum physics. They behave, also, as a "wave" (exactly like photons). In a "dual hole experiment" they produce interference (the picture of bright and dark lines) whenever we don't try to look at them. And they behave as particles whenever we try to do so.

So, the electrons and all the other particles (which are described by Quantum physics) are not less mysterious than the photons.

You asked:"And why don't radio waves from a transmitter seem to come as photons?... Does it at lower frequencies like from an AM radio station?" Yes, all these radio waves can be considered, also, as photons, although of a much longer wavelength. But these "low frequency photons" are, also, "low energy photons". So, it's difficult to exhibit their quantic behaviour, like the "visible (high energy) photons" do. For example, they cannot produce the photoelectric effect, as they don't have enough energy to make the electrons escape from the atoms. So, they are observed (and studied) like waves (and not like quanta).

A photon, by definition is a massless unit of energy.

If light (a photon) is a wave, then it's size depends on how far you are from it's origin, as it expands to fill all space as any other electromagnetic wave would do. I was about to say it's size depends on how long it has been shining. I think you know why I decided not to say that.

StandardsGuy, don't mess photons with waves. A photon itself is a "particle" not a "wave". Light behaves either as wave or as particles (photons) depending on the way of the observation (or the experiment that takes place). And the guest's initial question was "how big is the "light particle" -i.e. the photon-", not "how long is the light wavelength" or "how far can the light go"...

Hi G.K.,

I'm surprised at you. You know about the duality of light. You know that it has been said of light for many many years that "light travels as a wave, and departs and arrives as a particle". Einstein described the "particle" as a bundle of waves. No better explanations have been given. The "particle" is just something that we use to convince ourselves that we have some sort of understanding. We don't. The original guest didn't know what he was asking.

S

If I erect a vertical wire and cause electrons to move up and down the wire in a harmonic (sine wave) fashion, we observe, experimentally, that energy is radiated. The process can be described using "classical physics", and it was pretty well understood before quantum mechanics became revealed dogma. If that sloshing of electrons in the wire occurs at low frequencies (perhaps kiloHertz), and the energy of the quanta relates to h-nu, surely the photons of "AM radio" are of very low energy. Experimentally, I can take my miniscule crystal set to a point several miles (several wavelengths) away and capture enough energy, lots of photons, to hear the signal in my earphones. Whatever the size of those photons when they originated (from a slim wire), the size is essentially zero when they are destroyed in my hand-held receiver. I have yet to find a quantum mechanic to explain to me what size or duration they might have between the transmitter and the receiver. Non-quantum mechanics will speak wisely of Fourier analyses and such and pretend they know all about antenna patterns, backlobes, phase changes on reflection, etc., all of which seem a bit strange, if one is dealing with "particles." Like a Three-in-One God, we are asked to accept all this on faith.

OK, here is the problem. I slowly ramp up the current in my vertical wire (say charging a capacitor) and then suddenly dump that energy with zero left (not an oscillating spark, just a one-way flow of electrons). The radiation of energy goes as the derivative of the current, but if the current starts and stops instantly, goes in only one direction, what happens? You cannot do a Fourier analysis on an instantaneous, non-repeating function, can you? And, if the radiated energy is not an "electromagnetic wave", has no duration to speak of and no frequency, when what is the energy of the individual photons?

This is not a purely academic question. If one can create "non-sinusoidal" or "unipolar" electromagnetic disturbances (can't call them waves?), those propagating disturbances can be used to transmit information or to form a radar in a manner which no operational intercept receiver can detect, as the energy will not get through the tuning circuits. (Go ahead, show me a superheterodyne radio receiver which can detect a single short non-sinusoidal pulse of radio-photons) In addition, such "frequencyless" pulses should not excite resonant molecules, hence they should penetrate materials (sea water?) which absorb ordinary radio waves. There are, no doubt, a few problems in building such a stealthy radio system (how do you detect the signal?), but it appeals to me as an engineering problem. I challenge you quantum mechanics, photon counters, to solve the problem.

Forget QM; just use classical e&m. If it propagates, it's a wave. The frequency might be indeterminate but not nonexistent. BTW, dI/dt will never be infinite.

Esbuck's post is a series of erroneous hypotheses and conclusions.

The initial part attempting to analyze broadcast band communication links via analysis of photons is totally worthless, and either esbuck didn't read the discussions posted by myself and others, or he/she didn't understand what was posted. For anyone reading esbuck, please go back and read the initial responses, which explain in detail about wave-particle duality, and the difference between existential reality and our perception thereof. The only "faith" required of the reader is that of Socrates, who opined that the really wise man is the one who knows how little he actually knows.

As to the "thought problem" esbuck poses; it is no problem at all, and anyone who has ever set up an electrically short antenna will find the following treatment elementary.

Esbuck proposes an infinitely short and fast electrical current applied to a whip antenna and says because it isn't a periodic wave, it can't be treated by classical or quantum mechanics. Any time domain event can be converted via Fourier techniques into a corresponding frequency domain representation. If the time domain waveform is periodic, a Fourier series expansion may be used. If the time domain waveform is a single event, use a Fourier integral.

A time domain waveform with infinite rise/fall-time and no duration is called a delta function in mathematics, and an impulse function in physics. The frequency spectrum of a delta function is just the opposite of what was claimed by esbuck - it contains all frequencies out to infinity, with even distribution. A real world impulse doesn't contain infinite frequency coverage, because it doesn't have zero rise- and fall-times.

In fact, if you had an unknown passive device consisting of some combination of inductance, capacitance and resistance, and if you applied a delta function to the input and looked at the output you would completely characterize the device function, because all frequencies with constant amplitude and fixed phase were passed through it, and the output amplitude and phase vs. frequency relative to the input completely define the function of the (no longer) unknown circuit.

Now as TVP45 pointed out, you cannot physically design a circuit that provides zero rise- and fall-times, but you can get arbitrarily close. For instance, in my test facility I have several impulse generators whose spectral distribution is flat out to 1 GHz. These devices are used for calibrating EMI receivers, because of their flatness and wide frequency content. If you had a fast enough oscilloscope (I don't) you would see a pulse train of roughly 10 picosecond wide pulses at a 60 Hz rate. Don't let the periodicity lead you astray: the generator can be set to emit a single pulse. But if you're trying to make a measurement with a superhet receiver, it is easier if the impulse is repetitive. Not necessary, mind you, just easier.

If one were to apply the 50 Ohm output of an impulse generator to a collapsible whip antenna such as you get at Radio Shack, here is precisely what you would get:

Below the frequency at which the length of the whip is one quarter wavelength, the emitted field intensity will decrease with decreasing frequency. This is because an electrically short whip has an input impedance which is capacitive, which makes it harder to drive the lower you go in frequency. This is of course precisely the reason that HF or shortwave antenna tuners were developed - they place an inductance in series with the whip capacitance that provides a resonant short circuit, making it easier to get current to flow into the whip element.

At and above one quarter wavelength you will see a series of peak and anti-peak field intensities as a function of frequency, with a sinusoidal characteristic. This is because the whip is easiest to drive when it appears to be an odd-integer multiple of a quarter wavelength, and is very difficult to drive when it appears to be an even-integer multiple of one quarter wavelength.

A receiver equipped with a similar antenna would exhibit similar behavior, so the received signal would look like the impulse spectrum, multiplied by (technically convoluted with) the square of the transfer function discussed for a single whip antenna, because there are two.

Relative to Esbuck's sea water issue, the lowest frequency components would penetrate sea water better, because of the skin depth phenomenon. The high frequency components would be absorbed very near the surface. Once again, this problem has been solved - the VLF band is used to communicate with submarines for this very reason.

So there you have a complete qualitative discussion of what happens when you apply an impulse or delta function to a whip. Not only is it easy to understand, but there is absolutely no need to look at a quantum mechanical solution. Classical physics suffices completely.

As I and others have noted, repeatedly in this thread, quantum mechanics only becomes important when the wavelength of the radiation is short enough that photons start to interact with electron energy levels. That doesn't occur at frequencies we use for radio communications.

Thank you for you detailed answer. Unfortunately, it missed my point.

You say:

"Below the frequency at which the length of the whip is one quarter wavelength, the emitted field intensity will decrease with decreasing frequency. This is because an electrically short whip has an input impedance which is capacitive, which makes it harder to drive the lower you go in frequency. This is of course precisely the reason that HF or shortwave antenna tuners were developed - they place an inductance in series with the whip capacitance that provides a resonant short circuit, making it easier to get current to flow into the whip element."

I was postulating a non-resonant antenna, with a one-way current. (If you drive a whip from one end, obviously electrons go both ways) I'm thinking not of a dirac delta but of a step function. You can do your fourier analysis on it, but it isn't, I suspect, very useful, especially if you deal with multiple radiators.

Further, if one uses an impulse function which generates a broad band of frequencies or, for that matter, an impulse in the receiver, how do you detect the signal against a background of noise? Tune your receiver to any frequency, and you get the same signal. You will likely get a similar effect from a lightning bolt, which approximates the "thought experiment", except that usually there is some alternating current, back and forth, as well as the primary discharge.

I would like to provide some experimental back-up for my erroneous hypotheses and conclusions, but I was told I did not have the proper clearances to see the secret data.

I will cheerfully accept that quantum mechanics isn't important with long wavelength radiation, but that doesn't prevent my being curious about how quantum mechanics works with it. Do photons not exist at radio frequencies? If they do exist, it seems reasonable to ask what the "look" like. If, of course, they don't exist, there may be a Nobel Prize in there somewhere, when you figure out how and why the radio waves propagate in an unquantized manner.

Esbuck says I missed his point, stating:

"I was postulating a non-resonant antenna, with a one-way current. (If you drive a whip from one end, obviously electrons go both ways) I'm thinking not of a Dirac delta but of a step function. You can do your Fourier analysis on it, but it isn't, I suspect, very useful, especially if you deal with multiple radiators."

A whip antenna becomes resonant at one-quarter wavelength. I addressed the performance below, at and above one-quarter wavelength; therefore I addressed the non-resonant case as a subset of all the possibilities.

Step-by-step:

Esbuck stated: "If you drive a whip from one end, obviously electrons go both ways."

It is obvious if you drive it with an ac waveform, but not if you drive it with a single impulse, which was the case of interest to esbuck and what I therefore specifically addressed.

Esbuck stated, "I'm thinking not of a Dirac delta but of a step function."

Esbuck's original post (#42) described his waveform of interest as:

"OK, here is the problem. I slowly ramp up the current in my vertical wire (say charging a capacitor) and then suddenly dump that energy with zero left (not an oscillating spark, just a one-way flow of electrons). The radiation of energy goes as the derivative of the current, but if the current starts and stops instantly, goes in only one direction, what happens? You cannot do a Fourier analysis on an instantaneous, non-repeating function, can you? And, if the radiated energy is not an "electromagnetic wave", has no duration to speak of and no frequency, when what is the energy of the individual photons?"

That is not a step function, but a delta function, because esbuck described the current starting and stopping instantaneously. In fact you cannot apply a step current function to a short whip, because it is non-resonant, and as a load, looks like a capacitor. If you were to apply a step potential (Volts) to the whip base you would see (theoretically) an instantaneous current which then decreases from the peak following an exponential decay, as the whip capacitance charges up.

Esbuck stated, "You can do your Fourier analysis on it, but it isn't, I suspect, very useful, especially if you deal with multiple radiators."

Can't even buy a clue on that one. Of course you can do a Fourier transform of a step function, but you don't need to - it's so elementary you can find it in the CRC Standard Math Tables and lots of other sources. No clue where multiple radiators comes from in this discussion, but if you suddenly add extra whips, making a small antenna "farm," then the only difference is you have to look at the resultant field structure. If the whips are very close together, with max separation between the farthest apart at one-tenth wavelength or less, then you basically have a fat, lower impedance antenna. If the whips are a significant fraction of a wavelength apart, then you will have phase differences and in some directions you will have constructive interference, and in others you will have destructive interference (all a function of frequency, obviously). Thus the antenna farm gives you directivity over the isotropic pattern of a single whip operating against a ground plane.

Finally esbuck asks: "Further, if one uses an impulse function which generates a broad band of frequencies or, for that matter, an impulse in the receiver, how do you detect the signal against a background of noise? Tune your receiver to any frequency, and you get the same signal."

The answer is that the frequency spectrum of an impulse is coherent, whereas the frequency spectrum of thermal noise is incoherent. If you increase your receiver bandwidth while measuring coherent impulsive noise, the measured signal potential (Volts) increases in direct proportion to the change in bandwidth. If you increase your receiver bandwidth while measuring incoherent thermal noise, the measured signal power (Watts) increases in direct proportion to the change in bandwidth. Therefore the increase in measured signal for a coherent signal is the square of the change in the incoherent signal level (P = V^2/R).

Also, and just as fundamentally, if you know the receiver noise figure you know what your noise floor should be. If you have an even distribution of noise at a level well in excess of the thermal noise floor, that's a pretty good clue you have incoming coherent noise.

Esbuck concludes with:

"I will cheerfully accept that quantum mechanics isn't important with long wavelength radiation, but that doesn't prevent my being curious about how quantum mechanics works with it. Do photons not exist at radio frequencies? If they do exist, it seems reasonable to ask what the "look" like. If, of course, they don't exist, there may be a Nobel Prize in there somewhere, when you figure out how and why the radio waves propagate in an unquantized manner."

The basic definition of a photon is that its energy equals Planck's constant multiplied by its frequency. Clearly that can be done at any frequency. But the utility of the concept is nil when the frequency is so low that the photon energy is below that necessary to bump an electron from one state to another. Since the photons with lower frequencies don't interact with matter that way, from a utilitarian point-of-view we may indeed say that photons don't exist at low frequencies. If you can't measure or detect something, for all practical purposes it doesn't exist.

Even at frequencies where photons are detectable and measurable, it is not necessarily reasonable to ask what they look like. Quarks come in "colors" and "flavors". There are red and green and blue quarks. Understanding that quarks are the building blocks of sub-atomic particles whose dimensions are going to be orders of magnitude less than the wavelength of visible light, is one to literally picture colored quarks? And let's not get started on flavors. What about electron "spin"?

These are all just ways of describing certain behaviors we infer from measured behavior. We use the names of common everyday perceptions to denote uncommon concepts for which we would otherwise have to invent a name.

Hello emc c,

Just to ask,...........how is there room in your head for all the 'stuff' you know?

I know I know more, I just can't remember if I know it!

Take care, and very interesting! A keeper for sure!

"If the whips are a significant fraction of a wavelength apart, then you will have phase differences and in some directions you will have constructive interference, and in others you will have destructive interference (all a function of frequency, obviously). Thus the antenna farm gives you directivity over the isotropic pattern of a single whip operating against a ground plane."

While I don't care for "whips", which to my mind implies a resonant element, there have been advocates for "non-sinusoidal wave forms" (no phase, no wavelength) who advocate that, without a defined frequency, there will be no interference effects, no side lobes, for instance. Of course those advocates are delusional, regardless of their experiments.

As you seem to say, the array of antenna elements, driven by an impulse, would radiate at all frequencies which would seem to imply an infinity of interference patterns, one for each frequency. Thus, receivers or reflectors would not "see" all frquencies but would, depending on their location, get discrete frequencies, where there was constructive interference. Now, I don't need to scan my radar transmitter to illuminate at different angles; I can scan my (narrow bandwidth) receiver to catch reflections at different frequencies from different targets. (Yes, inefficient, but...)

"The basic definition of a photon is that its energy equals Planck's constant multiplied by its frequency. Clearly that can be done at any frequency. But the utility of the concept is nil when the frequency is so low that the photon energy is below that necessary to bump an electron from one state to another. Since the photons with lower frequencies don't interact with matter that way, from a utilitarian point-of-view we may indeed say that photons don't exist at low frequencies. If you can't measure or detect something, for all practical purposes it doesn't exist."

I'm old enough to remember when that argument was used to deny the existence of neutrinos.

OK, the radio frequency photon has so little energy that it won't bump an electron from one state to another. No argument there. It can't be detected? So what is it my crystal set is detecting? (No excited atoms, right?) Does it sum up the effects of lots of (coherent) photons? (Perhaps analogous to the thermopile detecting IR photons?) What does that say about the "size" or "duration" of those photons? How can photons be coherent in frequency (with other photons) if they don't exist in time? (probably a silly question) Another silly question. If the photon has a low frequency and long wavelength, and my antenna is miniscule (millimeters) compared with the wavelength (hundreds of meters), how long does it take a "passing" photon to be absorbed? What does a half-absorbed photon look like? Oh, electron states don't change, so the photon isn't absorbed? Perhaps it passes on by? But then it doesn't lose energy, so what excites my receiver?

Golly, you know the difference between a physicist and an engineer is that for the engineer you have to draw a picture. Can anyone draw a picture for me? A verbal picture will do.

The whip antennas on my old cars are electrically short in the AM band, and resonant in the FM band. A whip is a whip.

If you look at what it takes to detect a neutrino, giant vats of liquid chemicals placed underground, with very sensitive electronics to sense their passage through the vats, and then ask yourself why anyone would do this, the inescapable conclusion is that the only reason neutrinos were ever detected was that the government felt it had too much money and needed to burn some of the excess.

There is no point in repeating and re-repeating points I and others have made throughout this thread. There is no need to look at the particle nature of light unless you are looking at interactions between light and electron energy states. At lower levels of photon energies, the interaction does not occur and it suffices to look at light as a wave phenomenon. It is waves that interact with antennas, not photons. Your crystal set is responding to an rf potential delivered to it by an antenna which transduces an electromagnetic wave into an rf potential (that's what antennas do, by definition).

You need to go read Kraus or any number of other fine classic texts on electromagnetics and antennas. If you want references, I can give them to you off-line. There is complete treatment of all manner of antennas, and nary a word on photons.

This it for me on this topic, absent a new issue brought forward. I like to read and contribute, but repetition induces boredom, in both the reader and writer.

esbuck,

The thing to remember is that photons aren't real in the same sense that a '57 Chevy is. It's a way of talking about the effects we see. At high frequencies we see something that can be described as a photon; at low frequencies we don't. Somebody mentioned Quark flavor and it's kind of like that - just a description, not necessarily realistic. Nature does whatever she damn well pleases and we mortals then gossip about it and call it science. It's important to remember that any experiment we do or calculation we make doesn't change what actually happens (alright you entanglement folks - let me skate on that one, please?).

Well put.

A rational, detached from Anthropocentric kind of view, is required here.

Hello Guest,

This is a bit off the wall but worth looking at, especially regarding size.

3School of Information and Communication Engineering, Sungkyunkwan University,
Suwon, Gyeonggi-do 440-746, Korea
*Corresponding author: Ytakahashi@qoe.kuee.kyoto-u.ac.jp
Abstract: We have succeeded in fabricating a photonic crystal nanocavity
with a photon lifetime of 2.1 ns, which corresponds to a quality factor of 2.5
× 106. This lifetime is the longest recorded thus far in photonic crystal
cavities, and was brought about by improvements in the fabrication process.
Comparing our experimental quality factor with the results of calculations
shows that we have suppressed variations in the radii and positions of the air
holes composing a nanocavity such that their standard deviations are less
than 1 nm.
©2007 Optical Society of America Take care............

It's turtles on turtles all the way down.

OK! Here is my theory as outlined in "A Gestalt theory of light and related phenomenon."

We know that the electron is a charged particle and that it loses and gains energy by emitting and absorbing photons. What if, what the electron was emitting were pulses of electric energy, what could be more natural than for an electron to emit pulses of electrical energy ? Suppose the pulses that were emitted underwent polarization. See picture below:

A natural result of this would be that a solenoid field would be formed around the pulses of energy as seen in the figure below.

The final result would be a photon structure that posseses the properties of both a wave and a particle. See below.

Having got a possible structire for the photon which would explain to a large extent its seemingly contradictory wave/particle properties, we have next to think about how it propagates and why it does so at a constant speed.

Good Answer. And one of the better explanations. The solenoidal field is generated as the electromagnetic pulse travels through space/time or the aether as I prefer. Just like the em field down a wire.

Nice representation, Dragon

I won't buy it, DDjames. Essentially you imagine the photons like "small wave packets". It's not so. A photon itself is not a wave in any sense. For example in a "two hole experiment", if just one photon is emitted, it doesn't exhibit the picture of intereference on the screen (bright and dark lines). A lot of photons must be emitted (one by one or as a group) in order to see the picture of intereference (i.e. to exhibit wave behaviour).

Afterall, I could "accept" the electric field of the emitted "packet" that you described (although I can't understand even this... a packet of electric field???... polarized??? ... ??? ... anyway... ). But where is the associated magnetic field??? Don't forget that the light is an electromagnetic wave (i.e. is a combination of electric and magnetic field which travels at a speed 3x10⁸m/sec)

"...doesn't exhibit the picture of interference on the screen..."

That's because unlike Fermions, Bosons do not obey the distribution patterns derived from Pauli's exclusion, only that when a bunch of photons are interacting as a beam, wavy patterns may accrue, concerning the beam.

The Slit-Experiment, is simply a vivid demonstration of De Broglie's description

I won't buy it, DDjames. Essentially you imagine the photons like "small wave packets". It's not so. A photon itself is not a wave in any sense. For example in a "two hole experiment", if just one photon is emitted, it doesn't exhibit the picture of intereference on the screen (bright and dark lines). A lot of photons must be emitted (one by one or as a group) in order to see the picture of interference (i.e. to exhibit wave behaviour).

Right, but remember that I have given only half an explanation here, namely a possible structure for the photon that accounts both for its wave and particle properties. In order to understand why the double slit experiments yields the results that it does, it is necessary to go one step further, namely to find out how a photon propagates through space.

We are all acquainted with the inverse square law as applied to light, it has been tested experimentally over hundreds of years and found to be true. (Not taking into account of course laser light , but the present theory does offer a mathematical explanation of why this is so and predicts accurately how far a laser beam will go before dispersing.) Present scientific wisdom is that light once it is emitted, exists forever or until it comes into contact with matter and is absorbed by an electron. Is this really true, has it been proved to be so by our senses. The present theory (A Gestalt theory of light and related phenomenon) holds that light (i.e., photons) does not possess the quality of immortality, it is prone to attenuation just like anything else. If you are willing to give me a fair hearing, just listen.

OK take a 1 watt light source, by the time that light source has traveled a distance of 2 kilometres, it is attenuated by four million times. In other words if we are to stick to a strictly empirical understanding of the facts, it has ceased to exist. So what happens to it? One possible explanation is that it loses almost all of its energy and transforms into a 'virtual" photon, possessing an energy of about 10^^-18eV. In this form it is to all purposes invisible to matter and because of the extremely low energy that it possesses, transcends the Laws of Conservation and can in effect exist for ever. Gestalt theory states that we live in a sea of these 'virtual' photons that could have had its existence at the time of the big bang.

Right, so what happens when an electron emits a real photon, the "virtual" photons in its line of emission immediately line up in a positive to negative manner, forming a line whose ends rest on infinity. The energy of the real photon travels along this line of "virtual" photons at a speed of 3x10^^m/sec, in its totality (i.e., no energy is lost). In order to imagine how the photon travels along this line of "virtual" photons it is necessary to think back to one of Benjamin Franklin's early experiments with a Leyden jar. He arranged for a line of uncharged leyden jars to be connected in series (positive terminal to negative terminal), at one end of this line of leyden jars a soldier was told to hold one terminals while the other end of this line of leyden jars was connected to a live Leyden jar. The whole of the current from the charged Leyden jar, traveled along the line of uncharged Leyden jars and reached the other end intact, knocking the soldier ( some would have it as several soldiers) down. This is precisely the way that the energy of a photon travels down a line of 'oriented' "virtual" photons. Thus it fulfils one of the observed properties of a photon, it preserves its 'identity' (i.e. energy intact, no matter the distance that it travels.) It is evident that three of the properties of a photon, namely that it is particle without mass, that it travels at a speed of 3 x 10^^8m/sec, that it preserves its identity, have already been accounted for.

Also think of the qualities of the 'virtual' photon sea, it approximates extremely closely to the ether, predicted of old, it is colourless, tasteless, odourless, is completely invisible and undetected to matter, yet at the same time it practically incompressible.

This post is already a bit too long, it will have to be continued at a further time.

Very interesting. Please continue, I believe you almost have it. Focus on the "virtual" photons. They are not virtual at all. Think aether and surface tension of water.

Regards Dragon

Hi! Dragonsfarm,

Thanks for the positive comments. I am especially drawn to your signature: " Ignorance is the beginning of knowledge. Heresy is the beginning of wisdom. The ignorant heretic is the wisest of all."

OK, while questions might arise about the type of aether in question, at least it is agreed that there must be an aether. The AAD scenario (Action at a distance) or even the highly ingenious theory of James Clerk Maxwell of self supporting and self generating electric and magnetic fields is now known to be less than perfect and doesn't fit the facts as they are known. In fact modern science does not accept the existence of separate electric and magnetic fields, experiment has shown that there is only one field and that is the electromagnetic field, this is the only field mentioned in the four forces, (i.e., strong force, weak force, electromagnetic force and gravitational force.). That said, it is necessary to look in more detail at what is being proposed viz-aviz the propagation of light and electromagnetic radiation.
What are the properties of the photon as we know them:

1) It is a particle without mass.

2) It possesses the properties of both a wave and a particle.

3) It travels at the speed of C ( 3x 10^^8 m/sec)

4) It is electrically neutral.

5) It preserves its identity ( energy) almost indefinitely.

6) It propagates in straight lines.

The photon structure I have outlined, accounts in an almost exact sense, for each of these properties, it is not wanting in any aspect. The solenoidal form I have attributed to the photon structure makes it electrically neutral, it has no mass, it travels at the constant speed of C, it preserves its energy almost indefinitely, it posseses wave and particle characteristics, and so on. No other theory can explain all the properties of a photon in a similar manner.

As for an explanation of the Double slit experiment, surely it is self-explanatory. If there exists an aether as postulated, then it follows that this aether, although invisible, would experience diffraction as it passes through the double slits. Since the aether is the medium through which photons ( light ) experiences propagation, it follows that a beam of light directed on to the double slits would in turn experience interference, similarly, single photons sent through the slits would also naturally emulate an interference pattern. In fact, I can safely say, given the presence of an aether, that it would be extremely strange if they did not undergo interference. More in the next post on radio waves, if you approve.

"...No other theory can explain all the properties of a photon in a similar manner..."

How about the following minors, just for good measure, that is, to keep us on the safe side:

1) It is a particle without rest-mass - (mass acquired with velocity - to comply with Lorentz moving mass clock and ruler, later adopted by Einstein).

6) It propagates in straight lines, bent only in the presence of another mass - (aether being gravity for that sense)

How about the following minors, just for good measure, that is, to keep us on the safe side:

1) It is a particle without rest-mass - (mass acquired with velocity - to comply with Lorentz moving mass clock and ruler, later adopted by Einstein).

6) It propagates in straight lines, bent only in the presence of another mass - (aether being gravity for that sense)

A bit of scientific trivia: The theory that you speak of and attribute to Lorentz was actually proposed by George Francis Fitzgerald, an Irishman. Fitzgerald reasoned that it was the pressure of the ether 'wind' that compresses matter, just as an elastic object moving through water becomes shortened in the direction that it is traveling . Fitzgerald's theory had a major advantage because it was impossible to disprove. It said simply that there was a one dimensional contraction in the direction of motion that increases as velocity increases. It was Lorentz, however who expressed the theory in rigorous mathematical terms. Henri Lorentz was later to comment " I proposed and Einstein disposed" or words to that effect.

It is interesting that in the sense of physical properties of the aether as visualised by Lorentz and Poincare for example, would not apply at all to a "virtual" photon ether, simply because in a 'virtual" photon ether light propagates because of and through the medium of an aether. The aether is not a distinct physical entity as visualized by Lorentz etc.,

"The Gestalt theory of light and related phenomenon" offers another explanation for the phenomenon of gravity based on Sir Isaac Newton's conjectures on the subject. As a matter of fact Einstein was very much in favour of some kind of electromagnetic type of aether, as was Henri Lorentz.

And, of course, ever eager to muddy the water, I might point out that a perfectly good way to view propagation is from the point-of-view of the photon. Since it is moving at the speed of light relative to everything else, the photon sees all length as zero and all time as infinitely slow. Thus, it doesn't need to propagate since it already "is" everywhere, forever.

If so, are you suggesting that the Michelson–Morley experiment is invalid in the sense that Aether does exist to resist objects passing through it ?

I thought the whole point of that experiment concluded with that Aether is only a concept, a frame of mind, (just like Time is, if you will) but is not an actual, physical entity

It does, only that dark matter is the name we chose to describe a lot of mass which is not luminescent, (or at least directly observable, such as stars or nebulae).

In "dark matter", we relate to "dark" cosmic dust (heavy elements left over by super novae) or even the accumulative mass of black holes. These cannot be analysed by direct obsevation and spectrography, to asses the element-composition, temperature range and mass involved.

The term was coined to point to the amounts of "hidden" mass, not directly observable, but such that exerts it's gravity effect on large-scale celestial systems such as galaxies or galaxy-clusters.

"not directly observable,..." Or even indirectly observable. Dark matter's existence is still a theory that has a few holes in it. Its "gravitational effects" could be attributed to the "Beifeld-Brown effect", whereas electrical charge effects the actions of matter in motion. Interesting research by the way, you might want to check into it.

Regards Dragon

And, of course, ever eager to muddy the water, I might point out that a perfectly good way to view propagation is from the point-of-view of the photon. Since it is moving at the speed of light relative to everything else, the photon sees all length as zero and all time as infinitely slow. Thus, it doesn't need to propagate since it already "is" everywhere, forever.

A very apt explanation by TVP45 of the disassociation of light, and in fact this is exactly what QM does claim, (although not so succinctly). The theory of an aether was rejected when the Michelson-Morley experiment proved that the aether wind does not exist, and that the speed of light is constant, regardless of the frame of reference. The concept of an ether then became a moot point because it had no practical use. Maxwell's field equations for electromagnetism, effectively did away with the need of a medium and Einstein stated that there was no need for an ether because as he put it :…….." The electromagnetic fields are not states of a medium and are not bound down to any bearer. But they are independent realities which are not reducible to anything else.

But forgive me, for taking a leaf from Dragonfarm's book: Namely "Heresy is Wisdom".

I will question this statement, where do these electromagnetic fields originate? We have demonstrable evidence that electromagnetic fields arise from a flow of current or in other words from electrons, so one aspect of this phenomenon seems to tell us that they have no independent existence, which is in a sense a contradiction of the statement made by Einstein, that the electromagnetic field is an independent reality.

What we often lose sight of in the study of science is the Historical perspective. Concepts and theories were developed at a time when the pool of available knowledge was limited, and sometimes these were never revised even though contradictory evidence existed or new facts had come to light(forgive the pun). For instance Maxwell's field theories were formulated more than eighty years before the existence of photons was even suspected. Yet the theory remains, although increasingly side lined, virtually unchanged today. Would it have been changed if the existence of photons were known at the time, I have little doubt that this knowledge would have changed things considerably.

A lot of the confusion arises out of the manner in which the aether was conceived by physicists of the time. They envisaged the aether as a separate medium through which light traveled, something akin to the way in which sound travels through the atmosphere. The 'virtual' photon aether proposed by Gestalt Theoory is different, initially the 'virtual' photons are randomly oriented, in the presence of a real photon, the 'virtual' photons of the field line up in a line whose ends rest on infinity and the energy of the photon travels along this line of oriented photons. Thus in the case in point, although the speed of light is always constant, irrespective of the frame of reference, and although the light is traveling at relativistic speed, it does not exist everywhere simultaneously as TVP45 theorises, instead it spreads out (in the case of ordinary incoherent light) in accordance with the inverse square law(Gestalt Theory has a mathematical explanation of why this happens.) This of course is far more in keeping with what the evidence tells us, than to view light as something that undergoes 'disembodiment' and only appears at the point of detection.

In case anyone is intested in exactly what 'virtual' photons are, here is a new post that I started.

Here is a new twist on photons.

"When researchers talk about optical forces, they are generally referring to the radiation pressure light applies in the direction of the flow of light," said Tang. "The new force we have investigated actually kicks out to the side of that light flow."

This is from a Globalspec article's source article. http://opa.yale.edu/news/article.aspx?id=6245

Brad