# Light acts as a wave but travels in a staright line right

1. Feb 13, 2005

### The_Thinker

I'm just trying to get the right picture of how light is perseved by us right now.... Does light spread? as in does one photon of light split up as it travels through vaccum or does a photon stay as a ray and there are an innumberable number of these guyz out there which is why light is seen everywhere? Basically does a ray of light continueously spread as it travels through vacuum.....?

I'm a bit confused by this whole thing.....

2. Feb 13, 2005

### Kane O'Donnell

'Rays' of light are an idea that was introduced to make rough calculations about lenses and mirrors and so forth. They're just an approximation.

'Waves' of light are the statistical result of gazillions of single photons. You can treat light as a classical wave and get many of the same experimental results provided you have a high enough light intensity to make sure the wave is 'smooth' or filled out, but the only theory of light consistent with all the experiments I can think of off the top of my head is the photon theory, where photons are *quantum* not classical objects and are measured as particles but statistically show wave behaviour.

Kane

3. Feb 13, 2005

### Kane O'Donnell

Does light spread? Under some conditions, yes, because waves 'spread' (diffract) and light can be thought of as a wave if the light intensity is high enough and frequency low enough.

Photons don't split as far as we know, you can only ever measure them in a single place.

Kane

4. Feb 14, 2005

### HallsofIvy

Light from a "point" source (such as an electron) spreads out in a sphere.

That's very different from a "light ray".

5. Feb 14, 2005

### The_Thinker

ahh... i get it now... thz guyz