Are Photons Actually Infinitely Small Particles?

[sophiecentaur]

When you see the double slit experiment with water waves, do you doubt that the waves went from place to place? No, because the observation tools are high enough quality to see the intermediate steps. You apparently want to revert to action-at-a-distance simply because we haven't constructed adequate measuring devices. Who's making the "huge assumption" now?

I don't doubt that the waves, in general terms, 'went from place to place' because I can actually observe the process, which is based on statistical analysis of a large number of 'events' and which fits the straightforward Maths of wave propagation. But I cannot be absolutely sure that their motion is a totally smooth and continuous one because I cannot observe at a very small level. They could be going in a series of small jumps (or even big ones), for all I (or you) can tell

In the case of a photon, I cannot tell anything about its motion except that I have assumed it to have left the source in my experiment and it can be measured / detected just once on its journey. I have no idea 'what it was doing' in between and neither can I predict what it would have done if I hadn't observed it. I can't even be totally sure that the photon I have detected even came from my source. However, I do 'accept' that it follows a general statistical trend, because of the history of measurements of such phenomena.

So, in both cases, the microscopic and macroscopic, big assumptions are made if we say that there is a direct correspondence between the mathematical model we have used and what we have observed. I say that the 'comfort' is in feeling that there is, in fact, a correspondence. Tomorrow morning, someone may come up with a good reason to shake that faith and I shall not be upset. Just interested and probably very confused!

My "comfort" with it is no more trivial than your "comfort" with the currently accepted theory.

I have a problems with that statement. Firstly, I should like to know what 'currently accepted theory' you claim that I adhere to. Secondly, I am not clear about what theory you actually favour.

My view is that no theory is likely to be sufficient, ultimately, but I take comfort in the ability of many theories to predict stuff 'well enough' to make things like computers and TVs work.

 

[Q-reeus]

As a mathematical tool the Feynman path integral approach which posits a particle/photon simultaneously takes all possible paths between A (emission) and B (detection/absorption) obviously works. Handily all those paths but the intuitively expected 'straight' ones (depending on whether wave or particle properties are observed) cancel out to high probability. Few surely believe that literally all paths are actually taken at once. The position that there may be literally nothing between A and B is another thing again. Gravitational deflection of light has an easy intuitive explanation assuming continuous particle/wave traversal. There is a sensible explanation here when nothing in-between is considered possible?

 

[Cthugha]

A photon is definitely not a localized em wave or "packet". For ordinary optical frequencies the required electric field strength is 10+ orders of magnitude too high.

This is plain wrong by the way. Ever heard of single photons on demand or single photon turnstile devices?

If something goes from place to place, it has to traverse the intermediate space. If you create a theory that doesn't have that as a fundamental part, then your theory is either tracking fictitious quantities or your theory is simply a higher level calculation shortcut.

Well, only if you are wearing 19th century glasses. Also that statement is ill defined until you state what sorts of phenomena are covered by "something". Do you mean only classical particles? Do you also mean more abstract entities like fields and their energy density? What about the cases where just information goes from A to B like in quantum teleportation? Does the information also have to traverse the intermediate space?

 

[sophiecentaur]

@Q-reeus
Feynman was absolutely great with his Physics. He never 'believed' anything and never actually (afaik) made definite statements about reality. He was as slippery as an eel when challenged about such matters and always made statements which were loaded with caveats about the assumptions involved. He was a 'good lad' with the totally right attitude but has been treated a bit like Monty Python's Brian in that many people take, as gospel, statements he made with the greatest of care. They then over-interpret them and quote them way out of context.

 

[Q-reeus]

...He was as slippery as an eel when challenged about such matters and always made statements which were loaded with caveats about the assumptions involved...

And crabby at times too - based on a recent free showing! But I will agree with the sentiment it's all pretty pointless arguing this or that unless one's pet idea can lead to experimentally verifiable 'new truth'.

 

[sophiecentaur]

I have this theory about the Moon and Cheese . . . . . .

 

[Q-reeus]

I have this theory about the Moon and Cheese . . . . . .

Forget it - sure to be full of (Swiss variety) holes!

 

[Cthugha]

I have this theory about the Moon and Cheese . . . . . .

Oh, this has already been published. See Wallace, Gromit, et al., "A Grand Day Out", Aardman Animations (1989)
or have a look at the summary of this research article at
http://www.wallaceandgromit.com/films/granddayout/about.html

 

[harrylin]

[..] Well, only if you are wearing 19th century glasses. [..]

That sounds like a typical 20th century reply.

Does the information also have to traverse the intermediate space?

Do you have a model in which something goes from A to B without traversing space in between? If so, what model is that?

 

[Cthugha]

That sounds like a typical 20th century reply.

Indeed. My 21st century glasses are being repaired right now!

Do you have a model in which something goes from A to B without traversing space in between? If so, what model is that?

Well, that depends on the somethings. There are lots of experiments on quantum teleportation which get states from A to B using entanglement. Even highly non-classical states have been teleported this year. This can be described in a non-local manner. Now the "somethings" come into play. There is no information exchange associated with that teleport as we all know, so what qualifies as a something? And which went from A to B? The state of the light field? The information carried? The photons? And if we are discussing photons are we discussing its probability amplitude or the energy density of the associated field? The spatial dependence of both can be very different. Which quantity is the important one in tunneling? That kind of question is too fishy to give a clear answer while it is about "something".

One of the first things I learned when writing papers is that it is a very bad idea to claim "XXXX has to" unless you have absolutely rock solid evidence that every other possibility is completely ruled out. These claims can kill papers. In fact, I do not propose any specific model, but as long as there are tenable models involving nonlocal influences or similar stuff, I would not dare to declare that "everything" has to go through all space in between.

 

[hbjon]

I can go along with most of that.
SO why is it that the Photon is treated by all and sundry as something with the same sort of 'reality' as a cannon ball? It seems to me that it only serves to confuse. Isn't it time to make it more plain to the World that photons are not like that at all?
How many times do we read that the Photoelectric Effect 'proves' that photons are particles?
Q reeus made the comment a few posts ago. All the photoelectric effect shows is that E =hf and that energy interactions with em waves are Quantised. Can't we, as the relatively well-informed, do the World a favour and start putting things a bit more accurately?

In photoelectric effect, does the cannonball(s) splatter energy on the nucleus, causing the electrons to lose some of their hold on the atom? Doesn't a direct hit force the electron to move towards a more electronegative atom? Help me here. My memory does't serve me. The photon originates from the nucleus or the electron in qm?

 

[sophiecentaur]

In photoelectric effect, does the cannonball(s) splatter energy on the nucleus, causing the electrons to lose some of their hold on the atom? Doesn't a direct hit force the electron to move towards a more electronegative atom? Help me here. My memory does't serve me. The photon originates from the nucleus or the electron in qm?

The photon interacts with the whole system and causes the electron to depart.