I was listening to a podcast last night about the relationship between the distance of a light source generating photons and the age at which you are seeing the object. However, I’d never really thought about how light travels as an individual photon, and found this fact a bit mind-blowing as I’d never thought about the ‘journey’ from the perspective of the photon. This also applies to radio wave propagation through a vacuum.
From the perspective of a photon, which travels at the speed of light (about 299,792 kilometers per second in a vacuum), time doesn’t pass in the usual sense as it does for objects traveling at slower speeds.
In special relativity, time dilation occurs as you approach the speed of light. For an observer traveling at the speed of light, time essentially “stops.” So, for a photon, from the moment it’s emitted to the moment it is absorbed, no time passes. It doesn’t experience the journey at all—it would “experience” its entire path across the universe as an instantaneous event, no matter how far it travels.
This is a bit of a mind-bending concept because, from the perspective of us humans, the photon might travel millions or billions of light-years. But to the photon itself, that journey is essentially zero time.
Radio waves, like all electromagnetic radiation, travel at light speed in a vacuum, and so from their “point of view” (if we could define one), the trip happens in zero time.
Neither had I until the recent developments of photonics both for quantum stabilisation (which I personally believe will be the catalyst for leaps in qubit scale advancement over the more well documented cooling for stability methods, and photonics for IO instead of traditional silica (in other words using light as a processing method over tradition silicon chip IO).
Then there are advances in photonics for quantum application in communications. It’s a mind blowing field in general and I think will change the face of technology, industry, communications, security and, well, everything.
Question 1: How do we know its the same photon? - simply we don’t. Until something is observed its just a probability.
Question 2: Is the speed of light constant? - we can only say that it is when measured and we can only say that it is in our locality
Question 3: Given the above, there is nothing to stop (and its mathematically correct and has a finite probability) that a photon leaving Earendel (28 billion light years) could have dawdled along at say 1mph (as long as it didnt interact with anything) and then at the point of it’s interaction with your retina went back in time to the precise moment where it would appear that it travelled at 300million m/s. Just think of what it could have seen on its journey. Sounds ludicrous? Yes, possible also Yes.
If the above is true, and you could alter this in anyway (we can slow photons down, but can we speed them up?) , then you have faster than light communication (in theory).
If you consider an electron and its anti-particle the positron, is one just the same particle travelling backwards in time. Also remembering the arrow of time is dependent on the observer.
When Dr Who shouts “reverse the polarity” , he may not be that far off in terms of time travel.
Given all that, do I believe we will achieve FTL travel or communications or time travel? No, this is all happens on the quantum scale and unlikely to affect our macro world.
I was always ask myself when electromagnetic wave transform to photon. Light is also electromagnetic wave, isn’it? Is electromagnetic wave also a photon on say, 7MHz?
Heisenberg and Schrodinger are driving down the road when they’re pulled over by a police officer.
He walks up to the window and asks:
“Do you know how fast you were going?”
Heisenberg replies: “No, but I know exactly where I was”.
The officer says “You were doing 90.” Heisenberg throws up his hands and shouts “Great! Now I’m lost!”
The officer, thinking such a weird response deserves further investigation, tells Heisenberg to open the boot of the car. He looks in and sees a dead cat.
"Do you know there’s a dead cat in here?!” He shouts.
Photons all the way down. A great example is the cosmic microwave background. A nice soup of thermal RF at 2.7K But when those photons were emitted, the universe was a nice toasty 3000k, very much where you think of “photons” They have just been stretched by the universe on the way here .
What is really insane, is that the detectors that actually detect the CMB are photon counting. Some detector types are photon counting down to 1-cm! AFAICT Cold electron Bolometers are currently the best, and trying to avoid going down a rabbit hole here. Back when I was in school transition edge sensors were the best bolometers, and very curious now!
From a human physics perspective, absolutely. We physicists don’t have a closed model for phenomenon X. Sometimes it behaves like a wave, sometimes like a particle. Why should X take into account the fact that we humans find something comparable in our haptic world of experience?
It is irelevant for X. But not for me. Is it field or is it particle? It is huge difference. When and how field is transformed into porticle or when and how particle is transformed into EM field?
It’s always the same X.
In the space around your 40m dipole, it behaves like, for example, a sound wave in an organ pipe. X is reflected at the end, overlaps, and resonances occur.
If X hits a sensitive photosensor at extremely low intensity, it doesn’t show a continuous image, but rather individual photon hits with a random distribution.
73 Chris
Wave-particle duality. It’s both a wave and a particle(or it acts like one at least) at the same time.
How you perceive it depends on how you try and view it.
I used to run a couple of experiments for 1st year physics students. Electron diffraction (through graphite) and Planck’s constant by photoelectric effect.
Electrons viewed as a wave, light viewed as particles (photons)
Could I make antennas differently to catch 7MHz photons instead of waves? Can I catch enough 7MHz photons to understand the signal? Does this fit in a pocket or do I need acreage?
I should probably shut up instead of displaying my ignorance but this thread is fun reading.
Your 7 MHz dipole is already collecting photons. A field is formed when there is more than 1 photon present.
Homework. How many photons are required to generate a field strong enough to produce 1 uV across the feed point. Assume 73 ohms and 7.0 MHz as the photon frequency.
Addressing the remarks made several times above about quantum wave-particle duality, it’s important to point out that Physics doesn’t describe how nature actually is but rather provides a model of how it behaves. That’s particularly true for quantum physics. QP models are counter-intuitive but they allow scientists to make predictions and calculations with extraordinary accuracy which gives them confidence the models are pretty good - but certainly not the final word on the subject.
The models of Classical Physics are perfectly good approximations for most everyday ‘macroscopic world’ situations [including, apparently, getting Apollo spacecraft to the Moon and back] which is why most of high-school physics is taught that way.
Richard Feynman’s famous quote, “If you think you understand quantum mechanics, you don’t”. So, don’t feel bad, join the rest of us.
. i hope my first words post death are i told you it was a simulation! 
