# Photons confuse me [duplicate]

I'm not entirely sure if my question is valid or not but I'll ask it anyway. So my physics porf. told us the Photons are constantly in motion and they never come at rest and the sub-topics relating to it. Now since they never come to rest we cannot possible observe them, but [ There's always a but] if we're able to move at the same speed $$c= 3*10^8 m/s$$ we will be in a position to observer them. For instance I'm standing still and a fighter jet whooshes past me all I'm able to observe is a blurred object but if I'm in another fighter plane overserving the other plane, I'm able to look at every minute detail of the jet. Likewise if we move as fast as light then photons would seems stationary, but if they are stationary then how will be observe them because for us to appreciate the presence of a particle around us we need those proton to reach our retina. This might be an issue of Biology but my question is that is it possible for say a device to observe PHOTONS, or is there any way we can manage to observe them?

The thing you should keep in mind is that nothing can move at the same speed as light. In fact, as weird as it sounds, the light will always move at the same speed relative to you! This was first discovered experimentally by Michelson and Morley and led to the discovery of special relativity, where speeds don't add up in a simple way.

Also, there is a problem with what you call "observation", since as you say (and this is not only an issue of Biology) you need photons to go from an object to your retina or whatever in order to "observe" this object. In that sense, we cannot "observe" photons, since they do not emit photons. All we can do is catch them and measure some of their properties (energy and polarization), but we destruct them by doing so.

This is from an experiment that make one photon at a time to hit a screen , leave a footprint and so detect that a photon passed, even though with its zero mass and its enormous fixed for all frames velocity.

Single-photon camera recording of photons from a double slit illuminated by very weak laser light. Left to right: single frame, superposition of 200, 1’000, and 500’000 frames.

As photons accumulate from left to right we see the classical wave interference pattern of the light composed of those photons.

So we do observe photons by their interactions.

if we're able to move at the same speed c=3∗108m/s we will be in a position to observer them

Ah,but at high velocities close to c special relativity takes over, and this means that the closer you get to the velocity c the more fuel you will be burning, and at the limit you would need an infinite amount of fuel, so even in thought experiment it cannot be done.

• Really nice answer. Sep 26 '20 at 18:59
• Maybe I wasn't clear enough and I'm sorry about that. Like an electron, the photon is a particle, right? So apart from observing and confirming its presence by measuring it's properties can I theoretically ever see the particle? Now I might be the dumbest person on PSE but is it possible? Oct 11 '20 at 4:54
• We only "see" particles, know they exists, , by their interactions,. whether electrons,or atoms or molecules. That is why I gave the example above. Charged particles like the electron are seen in cloud and bubble chambers by the tracks they leave when interacting with a medium. see here physics.stackexchange.com/questions/520183/… Oct 11 '20 at 5:15

You write about a jet-fighter. We can observe it by photons coming from it (in whatever way) which subsequently enter our eyes (and being absorbed by a molecule in the retina).
Can we observe the photons themselves? It depends on what you mean by "observe".

Of course, you can't observe them in a way we observe jet-fighters or any other massive object that is able to send (by whatever means) photons to our eyes. The photon itself doesn't send photons to our eyes. When a photon hits our retina, can you say we have "seen" a photon? I guess not.
We can observe them indirectly by letting them enter some device that gives a click, a flash of light (which consists of photons too), or take your pick.

You write:

Now since they never come to rest we cannot possibly observe them

My girlfriend never comes to rest (actually she is sleeping right now), but I can see her and observe her. "Seeing her" is different though from "observing her". But I think that's a psychological issue. So that's no reason for being not able to see something. A photon indeed never comes to rest. It appears (it's created), has the velocity of light in every reference frame, that's the core of Einstein's Special Theory of Relativity (so, as you write, you can't fly together with them), or is absorbed by some massive electrically charged particle.
Even if you could fly aside from them, we come back to the problem that the photon can't be shined upon with light to make it visible, like in the jet-fighter case. But you can't.

So, yes we can build a device (or use a device already developed in Nature: the eye, which translates the impact of a photon in some kind of click, i.e., a tiny flash of light, though I'm not sure if only one photon, which has a frequency to which the eye is perceptible, will suffice to make this happen) to observe them indirectly, but we can't see them in full-color like we can see a fighter-jet.

• Why the downvote? Please leave a comment to explain why, as I have done for the answer below, given by @Peter. Then I can edit to improve the answer. Sep 26 '20 at 11:59
• Why are the two downvoters don't explain their downvote? Please, explain. I'm very curious. Is it just a random downvote? Is it some grudge? I don't understand. Sep 26 '20 at 12:25

An observer moving with a photon at the speed of light would in principle observe it as a static electromagnetic wave pattern, in the same way as an observer moving above a wave on water. How to make such an observation would be a problem, given that (as we now know) electromagnetic fields are transmitted by photons.

However, as others have noted, you cannot travel at the speed of light. If you could chase a photon at half that speed you would still see the photon traveling at exactly the same speed away from you.

• This is not really an answer to the question. Sep 26 '20 at 9:24
• If you could chase a photon at half that speed you would still see the photon traveling at exactly the same speed away from you. This is the point of the question. Can you see a photon? Sep 26 '20 at 12:25