# Light --- Is it really a wave? **URL:** \ **Category:** Factual Questions\ **Created:** [July 5, 2003, 4:52am UTC](https://boards.straightdope.com/t/light-is-it-really-a-wave/186348 "2003-07-05T04:52:01Z")\ **Posts on this page:** 6\ **Page:** 2
**Author:** ![Happy\_Fun\_Ball](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/happy_fun_ball/32/17664_2.png) [@Happy\_Fun\_Ball](https://boards.straightdope.com/u/Happy_Fun_Ball)\ **Post date:** [July 7, 2003, 5:15am UTC](https://boards.straightdope.com/t/light-is-it-really-a-wave/186348/21 "2003-07-07T05:15:16Z")
Excuse the lucidity (or lack of) of this post, it is late and I have had several glasses of wine… Light may be a particle but it is also definitely a wave. The wave nature of light is more than just a probability distribution, it has a physical nature. The best way to see and understand the wave nature of light is to start with Maxwell’s equations. Maxwell’s equations, in combination with the Lorentz equation, describe all of electromagnetism. They predict the effects of moving charges, the creation of magnetic and electric fields, and how said fields will interact with other charged particles. One of the solutions to Maxwell’s equations is a propagating electromagnetic wave. The speed of propagation is the speed of light. The speed of propagation also depends on the material the electromagnetic wave is traveling through, just as the speed of light does. Coincidence? The frequency of light actually covers a much larger spectrum than what is visible. From x-rays (which are pretty much indistinguishable from particles due to their small wavelength) down to radio waves with very long wavelengths. It is possible to create radio waves by actually moving a charged particle back and forth (say in an antenna). This creates a propagating electromagnetic wave. If we can accept that radio waves and light are the same beast, then light is a wave. I hope this argument is clear, as my thought definitely is not at this hour… Where’s my glass… ---
**Author:** ![Major\_Kong](https://avatars.discourse-cdn.com/v4/letter/m/b9bd4f/32.png) [@Major\_Kong](https://boards.straightdope.com/u/Major_Kong)\ **Post date:** [July 7, 2003, 5:18am UTC](https://boards.straightdope.com/t/light-is-it-really-a-wave/186348/22 "2003-07-07T05:18:54Z")
> [@](#): > > If we can accept that radio waves and light are the same beast, then light is a wave. But would you consider a single photon of a radio wave a wave itself? ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [July 7, 2003, 5:24am UTC](https://boards.straightdope.com/t/light-is-it-really-a-wave/186348/23 "2003-07-07T05:24:05Z")
> [@](#): > > \*Originally posted by Desmostylus \* > \*\*I like the SUV analogy, **scr4**. 🙂 \*\* I do, too. Everything doesn’t have to be either a wave or a particle (or a truck or a car). That’s the fallacy of the premise. ---
**Author:** ![Happy\_Fun\_Ball](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/happy_fun_ball/32/17664_2.png) [@Happy\_Fun\_Ball](https://boards.straightdope.com/u/Happy_Fun_Ball)\ **Post date:** [July 7, 2003, 5:46am UTC](https://boards.straightdope.com/t/light-is-it-really-a-wave/186348/24 "2003-07-07T05:46:06Z")
> [@](#): > > \*Originally posted by Major Kong \* > \*\*But would you consider a single photon of a radio wave a wave itself? \*\* Yes, it would still obey Maxwell’s equations and propagate as a wave. I know this is not a very rigorous answer… Slight hijack… Currently I am pursuing a MS degree in optics (electrical engineering). I am almost halfway through my course of study and I can tell you lots of interesting things about light, lasers, imaging systems, nonlinear crystals, etc…, but really nothing about quantum optics. One of my professors, a very highly respected physicist, once made the statement that we “should not even use the word photon until you have finished at least a year of graduate quantum physics, and even then you will probably be wrong in what you say when you do use the word”. Not wanting to take even one graduate quantum physics class (though I will be next semester), I try not to use the word. A photon is a weird beast and is somewhat beyond my comprehension at this point in my studies. Sure, I have read the Feynman lectures, and taken several QM courses in my undergrad days (BS in physics - about 12 years ago) and even been exposed to some quantum optics in my nonlinear optics courses, but not nearly enough to debate this issue. In all the optics courses I have taken we treat light as an electromagnetic wave (with the exception of light detection and generation). Perhaps **Chronos** or another of our respected doper physicists would like to say a word or two on this subject… For me, light is a propagating electromagnetic wave packet. ---
**Author:** ![Desmostylus](https://avatars.discourse-cdn.com/v4/letter/d/c57346/32.png) [@Desmostylus](https://boards.straightdope.com/u/Desmostylus)\ **Post date:** [July 7, 2003, 6:01am UTC](https://boards.straightdope.com/t/light-is-it-really-a-wave/186348/25 "2003-07-07T06:01:58Z")
> [@](#): > > _Originally posted by Eyer8 \* > \*\* …or another of our respected doper physicists would like to say a word or two on this subject…_\* We’ve already heard from at least four that I know of, including yourself. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 7, 2003, 8:48pm UTC](https://boards.straightdope.com/t/light-is-it-really-a-wave/186348/26 "2003-07-07T20:48:17Z")
> [@](#): > > (I named my son after one of them; I’ll leave you to guess which one) I’m deeply touched. So, how is little Chronos doing? The thing is, all particles are waves, and all waves are particles. It’s just that sometimes, one way of looking at them is more useful, and sometimes, it’s the other. When you’re modelling a baseball, it’s definitely easier to treat it as a particle. When you’re modelling gravitational radiation with wavelengths the size of the Solar System, it’s definitely easier as a wave. Electrons, or light of various frequencies, fall somewhere in between. [Previous page](https://boards.straightdope.com/t/light-is-it-really-a-wave/186348.md?page=1)