How come photons and...

[JacksSmirkingRevenge]

...other massless particles are affected by gravity as evidenced by gravitational lensing effects, black holes etc?
The closer to layman's terms this can be explained (if it can be, that is), the better. - I'm not highly edjumacated.

[Gawdzilla Sama]

...other massless particles are affected by gravity as evidenced by gravitational lensing effects, black holes etc?
The closer to layman's terms this can be explained (if it can be, that is), the better. - I'm not highly edjumacated.

Space curves. They follow space.

[Rob]

To my understanding: As photons travel along "space-time". As they go near something such as a black hole, which bends 'space-time" into a curvature, straight is no longer straight. So while the photon would travel straight it instead travels "straight" or curved from an outside perspective. I would imagine in the perspective of the photon it is still going straight though.

[Gawdzilla Sama]

To my understanding: As photons travel along "space-time". As they go near something such as a black hole, which bends 'space-time" into a curvature, straight is no longer straight. So while the photon would travel straight it instead travels "straight" or curved from an outside perspective. I would imagine in the perspective of the photon it is still going straight though.

tl:dr

[JacksSmirkingRevenge]

Of course.
I did know about this but never had the common sense to apply it here. I've been wondering about it for ages too.

Thanks for pointing it out.

[JimC]

Unlike other particles, their rest mass is zero, but as they zip along at the speed of light, they definetly have momentum (only a tiny bit), and momentum implies mass.

[Rob]

Yeah, I thought about pointing that out Jim. The only problem with velocity or momentum implying mass is that it is light particles traveling at the speed of light. In a vacuum, the speed of light is invariant. As such they have no rest mass. This isn't to say that their rest mass is zero but simply they cannot have a rest mass. I must admit, though, on a personal level I want to think the photon must have some mass yet there is no evidential support for this. *shrug*

[JimC]

Yeah, I thought about pointing that out Jim. The only problem with velocity or momentum implying mass is that it is light particles traveling at the speed of light. In a vacuum, the speed of light is invariant. As such they have no rest mass. This isn't to say that their rest mass is zero but simply they cannot have a rest mass. I must admit, though, on a personal level I want to think the photon must have some mass yet there is no evidential support for this. *shrug*

Well they definitely have momentum; when photons collide with an object, they transfer momentum to it, which is the whole principle behind light sails...

And in practical terms, rest mass = zero tends to mean the same thing as not being able to have a rest mass...

[JacksSmirkingRevenge]

I'm sure I've heard (or read) that about 4 kg of light falls on the earth every year. - A statement which is surely bullshit if photons are massless?
Was I dreaming or has anyone else heard this too?

[nellikin]

Isn't there a duality to photons? - wave (massless) and particular (mass-full?). So maybe the deflection is due to the particular-nature of them?

[JacksSmirkingRevenge]

I dunno - Every time I hear or read something about them it seems to contradict something else I've heard or read. Lol.


Edit -

(mass-full?)

- Massive.

[nellikin]

Massive, I like the sound of that

[JacksSmirkingRevenge]

...So, what happens when a photon is drawn beyond the event horizon of a black hole? Is it drawn into a place where space-time doesn't exist (or something ) and therefore cannot 'find' it's way out?

Also...When a photon is released (let's say, in a vacuum) does it just instantly start traveling at the speed of light, does it have to accelerate up to the speed of light or is it already traveling at the speed of light before it's released?

My apologies if these questions are stupid or irrelevant.



- I'm going to regret starting this thread, aren't I?

[nellikin]

I think photons may be emitted, not released. And yes, in a vaccuum, they would probably be emitted at the speed of light... Because, well, they are light (?)

[JacksSmirkingRevenge]

Emitted - Yes, a better word, methinks.

I'm finding it difficult impossible to imagine anything (massive or not) moving that has not previously accelerated.
- I think I'm stuck in some Newtonian view of things or something. I'll just have to somehow resign myself to the fact that I'm never going to even get close to understanding any of this stuff, at least to a satisfactory extent.