photons experience all of trajectory as one single event ?

[Widdekind]

if photons experience no proper time, then from a photon's perspective, every event on their flight path = simultaneous at the same moment of time, and also co-occurring at the same place (= location of photon)

 

so, from the photon's POV, every possible interaction, w/ space plasma, space dust, or some human HST; near or far, from its location of origination; are all perceived as simultaneous in space & time, a little like a "lifetime passing before one's eyes" sort of experience.

 

so, the from the photon's POV, it emerges into existence; is immediately presented with a panoply of options for interaction, similar to a multi-slit experiment ("which door to take"); and immediately "chooses" some selected option to interact with; and immediately its wave-function "collapses" into that interaction, with the "ignoring" of all the others.

 

meanwhile, that "instantaneous selection" of the photon, appears to play out, over millions to billions of years, of cosmic eons of time, from "everybody else's POV" (i.e. observers moving slowly w.r.t. the cosmic background radiation "rest" reference lab frame)

 

so, from some strange apparently paradoxical perspective, the photon is "fore-ordained" to some selected interaction, which it perceived as simultaneous w/ all others, and simply propagates thru space, to that interaction option ("exciting an electron in some piece of space dust, or some other space plasma ion"), where its wave-function dutifully "collapses". The photon "knew the entire time" what potential option for interaction its wave-function "would" eventually collapse into... that "instantaneous choosing" appears to play out, over vast cosmic distances, and times, from "everybody else's" POV

 

if you drew to space-time diagrams, the first for the photon; and the second for "everybody else"...

 

and if you drew a "string of pearls" along the trajectory of the photon, in the second s-t diagram, each "pearl" representing an event along the path of the photon (representing interactions with space plasma, space dust, human telescopes, etc.)...

 

then that entire "string of pearls" would map to the origin, in the photon's re-ference-frame...

 

so that all of those potential interactions, would be perceived, as simultaneous & overlapping in time & space

 

thus, the photon "poofs into existence", is immediately presented with a smorgasbord of potential options for interaction, picks one, and "poofs out of existence", in its own frame...

 

but that appears to play out over vast cosmic space distances & eons of time, in others' frames...

 

the photon "sees" all potential possible places-and-times of eventful interaction, to co-exist (spatially) and co-occur (temporally), as a single "multi-slit experiment"; the photon "selects some slit", and "goes thru that door"...

 

but everybody else's perception of space-time, is so warped w.r.t. the photon, that what "seems" to the photon to be a simultaneous multi-slit experiment, appears to play out over enormous spans of space and eons of time

[swansont]

There is no "photon's POV" that we can describe.

[ACG52]

A photon is not a valid frame of reference, because the speed of the photon is invariant in every frame of reference, so you can't use a photon as any kind of point of view. If you could, you'd be establishing an absolute, preferred frame of reference, which Relativity tells us doesn't exist.

[Widdekind]

A photon is not a valid frame of reference, because the speed of the photon is invariant in every frame of reference, so you can't use a photon as any kind of point of view. If you could, you'd be establishing an absolute, preferred frame of reference, which Relativity tells us doesn't exist.

i follow your first sentence...

 

why would a photon frame = "absolute preferred frame" ?

 

is there a possibility, that photons propagate at some smidgeon less than light-speed, i.e. there is an actual ontological "C = 3.01e8 m/s", and photons fly at "c = 3.00e8 m/s", or some such ??

[ACG52]

i follow your first sentence...

 

why would a photon frame = "absolute preferred frame" ?

 

Because it would establish a single consistent frame of reference across all inertial frames.

 

 

 

is there a possibility, that photons propagate at some smidgeon less than light-speed, i.e. there is an actual ontological "C = 3.01e8 m/s", and photons fly at "c = 3.00e8 m/s", or some such ??

No. Massless particles can ONLY travel at c.

[Widdekind]

photons don't dis-obey the Minkowski metric, yes ?

 

so, there is still no s-t interval, between any light-like-separated events, on a photon's trajectory...

 

and so the photon "must" experience no proper time ??

Because it would establish a single consistent frame of reference across all inertial frames.

 

No. Massless particles can ONLY travel at c.

 

so, you're saying, that the "v=C" frame would be a preferred reference frame ?

 

hypothetically, photons could carry some minuscule amount of mass << neutrinos

[ACG52]

 

 

hypothetically, photons could carry some minuscule amount of mass << neutrinos

Theory says they don't, and to the best accuracy of our measurements they don't.

[Widdekind]

Theory says they don't, and to the best accuracy of our measurements they don't.

 

so, then, they experience exactly zero proper time, all along their trajectories ?

 

photons are... and then are not... but they never experience any passage of proper time ?

[swansont]

so, then, they experience exactly zero proper time, all along their trajectories ?

 

photons are... and then are not... but they never experience any passage of proper time ?

How do you calculate the proper time?

[xyzt]

How do you calculate the proper time?

In flat spacetime, for example, [math]\tau=\int{\sqrt{1-(v/c)^2}dt}[/math]

 

If [math]v=c[/math] then [math]\tau=0[/math].

[moth]

If a photon's proper time is zero, how can photons have different frequencies?

[xyzt]

If a photon's proper time is zero, how can photons have different frequencies?

There is no connection between photon frequency and proper time.

[moth]

Is there any connection between proper time and momentum?
Considering the difficulty involved in arrainging for a single clock's world-line to intersect with the same photon twice, it's hard for me to understand how proper time relates to photons.

[xyzt]

it's hard for me to understand how proper time relates to photons.

 

I already answered this question, it doesn't.

Is there any connection between proper time and momentum?

The photon momentum is [math]\vec{p}=\hbar \vec{k}[/math] where [math]\vec{k}[/math] is the wave vector. So, no connection between photon momentum and proper time.

Edited July 8, 2013 by xyzt

[moth]

I apologize for my misunderstanding. When swansont asked Widdekind how he calculated proper time (for a photon) you posted an equation that doesn't seem to apply to the situation being discussed. Thanks for clearing that up for me.

[Widdekind]

If a photon's proper time is zero, how can photons have different frequencies?

 

 

 

the space-time interval, between all events, on a photon's trajectory, dx2 - dt2 = 0

 

for an observer moving between those events, i.e. a photon, that space-time interval = proper time elapsed (to the photon) = 0

 

sloppily stated, photons are "frozen bundles of EM field vectors", in a strained analogy, "frozen koosh-balls" (for want of worthier words)

 

as they propagate past you, their crests-and-troughs propagate past you, so you perceive a changing fluctuating oscillating EM field. Said fluctuating field is interpreted, as the "frequency" of the photon.

 

However, if you could "surf the crest or trough" of some photon, i.e. "hop on it at the speed of light", then the wave-train wouldn't be whizzing & propagating past you, and so you'd notice no frequency at all...

 

in terms of Relativity, if you accelerate parallel to the path of propagation of some photon, that photon red-shifts to you (photons flying the opposite direction, towards you, would be blue-shifted). So, if you could accelerate all the way to light-speed, then parallel-propagating photons would red-shift all the way to zero frequency, and so you'd indeed notice no changing EM fields fluctuating, no frequency, no elapsed proper time, you'd perceive the photons as "frozen koosh-balls of EM field".

 

photons, propagating along light-like trajectories, all along which the space-time interval is zero, experience zero proper time, yes ?? Is that not basic Relativity ? If so, then photons perceive every event they ever encounter, all along their entire path of propagation, as instantaneously co-occurring, at the same place (the photon's location), at the same proper time (one instant).

 

yes ?

[moth]

This is where i get (even more) confused.
Are you saying a photon exists from source to destination at one instant in time and the apparent motion is an illusion?
It seems like the peak we are "riding along with" is not moving or changing it's just there one instant and gone the next.
Can change occur without time passing?

 

Edit: Maybe change can happen in zoro time

Edited July 10, 2013 by moth

[Widdekind]

there is zero space-time interval, between any two events, on a photon's trajectory

 

e.g. "source to destination" as one of many examples

 

for the photon, that space-time interval (invariant for everybody, invariantly zero) IS the proper time experienced by the photon, whose world-line threads through those events

 

i.e. photons experience zero proper time, they are "frozen globs of EM field"

 

everybody else perceives change, b/c the photon is not there... then its "front" is there... then its "back" is there... then it is not there...

 

so everybody else perceives EM field oscillating to-and-fro', forth-and-back, and says the photons are "changing"...

 

no, the photons are "frozen"... what is changing, is their position RELATIVE to the observer...

 

that change of relative position, gives the observer a changing vantage point of observation, giving the impression of change...

 

somewhat similar to feeling your way along a car, first you feel the bumper, then the hood, then the windshield, etc. you perceive change, as the car rolls past your outstretched hand... but the car is "frozen" in a fixed shape

[moth]

So is the proper time for a photon's journey from sun to earth about 8 minutes or zero ?
It seems to me, if you allow c in the domain for calculating the spacetime interval, you get a verticle line on the graph and ds^2 is no longer a proper function.

[Widdekind]

event A = (0 AU, 0 min.) = emission of photon from sun

 

event B = (1 AU, 0 min.) = earth experience of "simultaneous" to emission at sun, but back on earth

 

event C = (1 AU, 8 min.) = earth receipt of solar photon

 

 

 

from B ----> C = 8 minutes of space-time interval = 8 minutes of "proper" time to earthlings...

 

from A ----> C = 0 minutes of space-time interval = 0 "proper" time to photon...

 

 

So, seemingly, photons in flight do not age, hence do not change, etc....

photons "emerge" into reality when generated...

photons then "are"...

until they are absorbed, when their quantum wave-functions "collapse", depositing their energy & momentum into some other quantum object...

when the photons "are not"...

but whilst they "are", they are timeless, changeless, "frozen koosh-balls of EM field vectors", whizzing at light-speed thru space-and-time...

 

never-the-less, a "photon reference frame" is not well-defined -- even though the space-time interval = 0 all along their photonic flight path is well definedly 0, so that their "proper time" elapsed "must" be well definedly zero

[moth]

Where's that lifeguard?...I keep wandering in over my head.

If your model is wrong, and not just strange to me, i don't know enough to say which.
What can proper time tell us about photons if it's zero for every photon.
It feels like an "external attribute" like a name, and not something "internal" like polarity or frequency.