Does a photon have physical volume or geometrical size?

[Norman Albers]

Is the fermi range lateral separation or longitudinal?

[skeptic]

While a photon's rest mass = 0, it's mass at c must be proportional to it's energy level. A gamma ray photon of sufficient energy can split into an electron and positron, both of which have defined masses and,of course, the process is reversable. What's really intriguing is to think about the size/length of a single medium wave photon in the broadcast band of say 180 meters wavelength. Remember ALL electromagnetic radiation is made up of photons, not just those frequencies in the visible light spectrum. While these light photons are conveniently tiny especially for the one by one two slit interference pattern displays, no physicist I've ever talked to has thought seriously about conceptualizing low energy, long wavelength photons. Is a single broadcast band photon 180 meters long and if not why?

[johnnymckiernan]

Yes, a photon has a physical size. It carries a tiny amount of energy but that doesnt mean it's tiny.

A laser has a very well defined wavelength,lambda;(633nm).It ,therefore, has a very well defined momentum,p=h/lamda.h=Plank's constant=6.6*10^-34Js.

Dp*Dx>h from Heisenberg

So Dx = 0.2m i.e about 20cm (..... the diameter of the beam is about 2mm)

How big is a photon?

Answer: I make it about 20cm long for a laser.

[lemur]

Is a single broadcast band photon 180 meters long and if not why?

 

Answer: I make it about 20cm long for a laser.

 

This may be naive, but I'm wondering how a photon can have a volume/length if it is absorbed in a single instant by an electron? I mean, if different wavelength photons had different lengths/sizes, that would imply that they take longer or shorter time to pass or absorb into a given electron. So would you then say that the photon gets absorbed in its entirety instantaneously even though 180 meters of it (or 20cm) is lagging behind the point of contact? If you said that it took so much time for it to absorb, where has the electron gone in that amount of time? Plus, how did the photon affect the electron when it made contact, etc.? At this moment I am picturing a 180m EM field "blob" reaching an electron at the speed of light and getting sucked in as the electron speeds around the nucleus at ???speed. After all, the photon can't get partially absorbed right? But then can another electron or the nucleus pass through it as it is getting sucked into the moving electron?

[alpha2cen]

The spelling- photon confuses us.

How about change it other word for the future education?

For example---elecwaveton.

[lemur]

The spelling- photon confuses us.

How about change it other word for the future education?

For example---elecwaveton.

Why not change the word, "electron" to photonator? That sounds cool, like "terminator." "Elecwaveton" has an awkward dipthong with the "c" next to the "w."

Edited December 17, 2010 by lemur

[swansont]

This may be naive, but I'm wondering how a photon can have a volume/length if it is absorbed in a single instant by an electron?

 

 

It isn't. All transitions have energy widths, and because of the Heisenberg Uncertainty Principle, there is an uncertainty in how long the interaction takes.

[johnnymckiernan]

You are correct(in my opinion).The photon has a very definate energy (for the laser E=hc/lambda.....lambda is very precisely known(same with c).

 

 

but dE*dt >h.......By Heisenberg

 

so dt, the time for transition, is large.

 

It is not absorbed in an instant but over a minimum time given above (if it encounters another He atom).

This may be naive, but I'm wondering how a photon can have a volume/length if it is absorbed in a single instant by an electron? I mean, if different wavelength photons had different lengths/sizes, that would imply that they take longer or shorter time to pass or absorb into a given electron. So would you then say that the photon gets absorbed in its entirety instantaneously even though 180 meters of it (or 20cm) is lagging behind the point of contact? If you said that it took so much time for it to absorb, where has the electron gone in that amount of time? Plus, how did the photon affect the electron when it made contact, etc.? At this moment I am picturing a 180m EM field "blob" reaching an electron at the speed of light and getting sucked in as the electron speeds around the nucleus at ???speed. After all, the photon can't get partially absorbed right? But then can another electron or the nucleus pass through it as it is getting sucked into the moving electron?

 

Photons a readily absorbed by matter.

If the photon has the

same energy as a transition excited state of an atom then the photon will be absorbed.The speed of the electron in the atom is a few percent of c from the 1st Heisenberg Eqn viz dx*Dp>h

Where dx is the diameter of the atom.kinetic energy=p^2/2*m

where m=10^-30kg for the electron.

This means that the speed of the electron is not precisely know nor its direction within an atom.In such cases it is better to assign a probability distribution to it.

 

 

 

 

 

 

 

You are correct(in my opinion).The photon has a very definate energy (for the laser E=hc/lambda.....lambda is very precisely known(same with c).

 

 

but dE*dt >h.......By Heisenberg

 

so dt, the time for transition, is large.

 

It is not absorbed in an instant but over a minimum time given above (if it encounters another He atom).