Eli5 how does a photon not experience time when zooming toward point b? Wouldn’t other photons from point b passing it appear as time happening very quickly?
In: 425
“Photons don’t experience time” is a consequence of something called the Lorentz Transformation, which is a consequence of Einsteinian Relativity.
The idea is that time dilates as you approach the speed of light. That means that the closer you get to c, the slower you feel time move. (in comparison to whatever clock you define as stationary.)
But this effect approaches 0 as speed approaches c, so the only logical conclusion is that things traveling *at* c perceive 0 time. We of course cannot know what photons or other massless particles perceive, but there isn’t much of an option to say that they do experience time.
The speed of light needs to be the same for all observers. This was proven by the Michelson Morely experiment that proved there is no medium through which light travels.
This means that observers at different speeds perceive time differently to ensure that they measure the same speed of light. This is Special Relativity.
The formula for this is t = t0/sqrt(1-v^(2)/c^(2))
If v=c (velocity = speed of light, like a photon would have), then sqrt(1 – v^(2)/c^(2)) = 0, and you can’t divide by 0, so time doesn’t work st the speed of light.
Photons don’t experience anything, and they don’t have a frame of reference. This is a question that gets asked a lot, but the answer is, “You’ve asked a nonsensical question the math cannot address.”
The short answer is that there is no amount of time. The photon is created and travels to point B and no time passes from the point-of-view (not that such a thing exists) of the photon.
Things traveling faster experience time as moving slower (not just observe it going slower, actually experience time slower). At speeds people typically travel the difference is so small you wouldn’t notice. But it can be measured using incredibly accurate clocks.
The simplest way I can explain it is picture three people: one standing still (A), one on a bicycle (B), and one on a motorcycle (C). If the bike is going 5 m/s and the bike is going 10 m/s in the same direction. To person A the motorcycle looks like it’s going twice as fast as the bike, but to person B it looks like the motorcycle is only moving at 5 m/s (because *relative* to their speed, it is). Now let’s say the motorcycle is breaking the laws of physics and going the speed of light and the bike is somehow managing 100 m/s. To both persons A and C the motorcycle is going the same speed regardless of their own speed relative to it which means he experiences the same amount of time regardless of what the outside observer sees (because the relative speeds don’t change our observation of his movement).
Here’s a link to the experiment showing that faster objects experience time slower:
https://en.m.wikipedia.org/wiki/Hafele–Keating_experiment
u/Emyrssentry already explained the why, but I see you still asking some questions, so 2 things to keep in mind:
1. A photon isn’t sentient. It can’t sense anything. So no, it doesn’t sense time, it doesn’t sense other photons around it, it doesn’t sense anything
2. If you ignore 1, from the point of view of a photon, it comes into existence and then immediately goes out of existence. Whether that is the extremely small fractions of a second the photon took to travel from a light bulb to its destination to provide light, or that is millions of years traveling through space from a star that generated it to wherever it’s final destination is, from the point of view of a photon it is instantaneous and immediately ceases to exist.
This is one of several questions these days discussing photons and time.
Can some kind soul clarify what does it mean ‘to experience time’ wrt elementary particles? Is there a specific meaning to it?
I would imagine a photon is like a surfer riding a wave of “time”. The speed of the wave being at the speed of light. Maybe imagine each wave has an image frame on it as well. It would seem you would still experience the progression through time as it is a relative experience. If the surfer had a watch it would still appear to tick away at the normal rate relative to themselves. Everything around the surfer would still be propagating to them at the speed of light from other directions. So they would not be able to see any new waves from their origin and would see only the now relatively stationary waves of light unless they slowed down or changed trajectory. It would appear time stopped at the origin. When looking forward the events would appear to be occurring twice as fast as ordinarily and be color-shifted as well. In essence the time would appear to be warped depending on the direction viewed.
When you go really fast you start to go faster by experiencing less time.
And to go at the speed limit of the universe you don’t experience time at all, which is only possible for things without mass like light.
To the photon its created and absorbed in a instant.
To the light particle, the distance, the space, between objects is zero. It’s only to outside observers that there is a distance because as we move through time slowly, the space also increases.
Latest Answers