- #1
Jeff Root
- 76
- 6
I'm looking at the possibility of trying to measure the length
of photons as a Science Fair project. I know that photons are
often considered to be "point particles", and I know there are
fundamental limits on measurements due to uncertainty in
position and momentum. I also know that according to
special relativity, length is a relative measurement, and that
light is different from virtually everything else in that it is
always moving relative to every observer.
How can I define the "length" of a photon? I suspect that there
might be several different ways to define the length, and they
might each have advantages and disadvantages.
How might I go about measuring the length? One tool you
might suggest is an interferometer. I can probably build one
if I need to, but I doubt I could build a very good one. Visible
light would be easiest to use in some ways, but the wavelength
is awfully small. Radio waves have a much more convenient
wavelength, but they are invisible, and can't be detected one
at a time. So the two best choices both seem very bad.
I'm looking for any measurement than can be practically done,
even if it isn't very precise, that would tell me something about
the length of the photons I'm measuring. I might use a laser of
known wavelength/frequency (that I could also measure myself)
and do something to the beam that would have an effect that
would depend on the lengths of the individual photons.
-- Jeff, in Minneapolis
of photons as a Science Fair project. I know that photons are
often considered to be "point particles", and I know there are
fundamental limits on measurements due to uncertainty in
position and momentum. I also know that according to
special relativity, length is a relative measurement, and that
light is different from virtually everything else in that it is
always moving relative to every observer.
How can I define the "length" of a photon? I suspect that there
might be several different ways to define the length, and they
might each have advantages and disadvantages.
How might I go about measuring the length? One tool you
might suggest is an interferometer. I can probably build one
if I need to, but I doubt I could build a very good one. Visible
light would be easiest to use in some ways, but the wavelength
is awfully small. Radio waves have a much more convenient
wavelength, but they are invisible, and can't be detected one
at a time. So the two best choices both seem very bad.
I'm looking for any measurement than can be practically done,
even if it isn't very precise, that would tell me something about
the length of the photons I'm measuring. I might use a laser of
known wavelength/frequency (that I could also measure myself)
and do something to the beam that would have an effect that
would depend on the lengths of the individual photons.
-- Jeff, in Minneapolis