# what is light **URL:** \ **Category:** Cecil's Columns/Staff Reports\ **Created:** [June 10, 2010, 2:35am UTC](https://boards.straightdope.com/t/what-is-light/542611 "2010-06-10T02:35:49Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Johnk](https://avatars.discourse-cdn.com/v4/letter/j/59ef9b/32.png) [@Johnk](https://boards.straightdope.com/u/Johnk)\ **Post date:** [June 10, 2010, 2:35am UTC](https://boards.straightdope.com/t/what-is-light/542611/1 "2010-06-10T02:35:49Z")
Can’t light be a wave like water or sound? Electricity is the flow of electrons through a conductor. Maybe light flows through some unknown substance, like dark matter or energy and doesn’t really travel at all. * * * Link to staff report: [How can light be both a wave and a particle? - The Straight Dope](http://www.straightdope.com/columns/read/2087/how-can-light-be-both-a-wave-and-a-particle) ---
**Author:** ![Twoflower](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/twoflower/32/22_2.png) [@Twoflower](https://boards.straightdope.com/u/Twoflower)\ **Post date:** [June 10, 2010, 4:43am UTC](https://boards.straightdope.com/t/what-is-light/542611/2 "2010-06-10T04:43:23Z")
Your idea is about 120 years late. [Messers. Michaelson and Morley](http://en.wikipedia.org/wiki/Michelson%E2%80%93Morley_experiment) disproved the idea that light was transmitted through a substance back in 1887. ---
**Author:** ![Illuminatiprimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/illuminatiprimus/32/11520_2.png) [@Illuminatiprimus](https://boards.straightdope.com/u/Illuminatiprimus)\ **Post date:** [June 10, 2010, 9:28am UTC](https://boards.straightdope.com/t/what-is-light/542611/3 "2010-06-10T09:28:38Z")
But haven’t experiments demonstrated that light is both a wave and a particle? This is something I’ve never properly understood. ---
**Author:** ![ivan\_astikov](https://avatars.discourse-cdn.com/v4/letter/i/58f4c7/32.png) [@ivan\_astikov](https://boards.straightdope.com/u/ivan_astikov)\ **Post date:** [June 10, 2010, 10:25am UTC](https://boards.straightdope.com/t/what-is-light/542611/4 "2010-06-10T10:25:12Z")
And a particle of what? How can something without mass be a particle of anything, and if it has mass, how can it travel at c? ---
**Author:** ![MarcusF](https://avatars.discourse-cdn.com/v4/letter/m/67e7ee/32.png) [@MarcusF](https://boards.straightdope.com/u/MarcusF)\ **Post date:** [June 10, 2010, 12:09pm UTC](https://boards.straightdope.com/t/what-is-light/542611/5 "2010-06-10T12:09:04Z")
> [@Illuminatiprimus](#): > > But haven’t experiments demonstrated that light is both a wave and a particle? This is something I’ve never properly understood. IANAPhysicist - and this really needs an expert to explain properly - but I don’t think “experiments demonstrated that light is both a wave and a particle”. As I understand it experiments have demonstrated that light has both wave like and particle like properties - not the same thing. Once you get down to this sub-atomic scale quantum effects come into play and using words like particle and wave to try and visualise what is happening just adds to the confusion. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [June 10, 2010, 4:02pm UTC](https://boards.straightdope.com/t/what-is-light/542611/6 "2010-06-10T16:02:39Z")
> [@ivan\_astikov](#): > > And a particle of what? How can something without mass be a particle of anything, and if it has mass, how can it travel at c? You could try reading any of a thousand popular science books on the subject. The short answer is that what you call a particle is a manifestation of something much more basic, a thing that contains energy. It may contain mass or may be massless but its properties emerge the same way. (One version of string theory says that all particles come from open ended strings, except the graviton, which is a closed loop string.) Why wavicles didn’t catch on as a name surprises me, since it better gives the dual nature of something that is neither a particle nor a wave but can give the appearance of either when looked at a certain way in the macro world. There are endless numbers of good explanations of this to be found. I strongly recommend that anyone with an interest in the subject - and that should be everybody - and especially those who purport comment on science should be acquainted with them. ---
**Author:** ![John\_W.Kennedy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_w.kennedy/32/1031_2.png) [@John\_W.Kennedy](https://boards.straightdope.com/u/John_W.Kennedy)\ **Post date:** [June 10, 2010, 4:10pm UTC](https://boards.straightdope.com/t/what-is-light/542611/7 "2010-06-10T16:10:32Z")
Let’s just say that light obeys certain equations, and certain of those equations are the equations that waves obey and particles don’t, and certain of them are the equations that particles obey and waves don’t, and that’s weird (from our point of view), but that’s how it is, and complaining about the weirdness doesn’t make it go away. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [June 10, 2010, 5:28pm UTC](https://boards.straightdope.com/t/what-is-light/542611/8 "2010-06-10T17:28:03Z")
> [@Illuminatiprimus](#): > > But haven’t experiments demonstrated that light is both a wave and a particle? This is something I’ve never properly understood. You and some of the smartest people who have devoted their lives to researching the field of quantum mechanics. The truth is that what we perceive as discrete phenomena on the everyday macroscopic level that we see is actually only a fuzzy approximation of the reality of the underlying mechanics, although due to a phenomenon called [decoherence](http://www.physics.ubc.ca/~jfolk/decoh.html), it is also the most precise measurement we can make of a large system that doesn’t have some kind of uniquely well-ordered low energy states (like a [Bose-Einstein condensate](http://www.colorado.edu/physics/2000/bec/what_is_it.html)). The supposed paradox of light being both a particle and a wave exists only because of the nomenclature we have applied (“photon particle” or “light wave”) to it carries the connotations of the way we think things work on the everyday level. As **John W. Kennedy** said, phenomena at the quantum level can be described mathematically by applying both particle models (when dealing with individual fundamental “particles” or discrete collections thereof) and wave mechanics (when referring to large coupled groups of fundamental particles). This doesn’t mean that one model or the other is better; it means that we’re all blind men in a room with an elephant, and each of us is describing the isolated piece that we’re touching. The reality of quantum mechanics is so foreign to our everyday, seemingly causal experience that it just seems wrong, even when it works outstandingly well at making highly precise predictions. I’m currently reading [_Particle or Wave: The Evolution of the Concept of Matter in Modern Physics_](http://www.amazon.com/Particle-Wave-Evolution-Concept-Physics/dp/0691135126), and I think it provides not only a decent explanation of the particle/wave duality, but also gives a very good context for the understanding and development of quantum theory in non-technical terms. Stranger ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [June 11, 2010, 12:14am UTC](https://boards.straightdope.com/t/what-is-light/542611/9 "2010-06-11T00:14:15Z")
> [@Stranger\_On\_A\_Train](#): > > You and some of the smartest people who have devoted their lives to researching the field of quantum mechanics. Richard Feynman is famously supposed to have said “If you think you understand quantum mechanics - you don’t understand quantum mechanics.” It’s strange that the best advice seems to be: Don’t try to understand - be content to accurately explain and predict all sorts of weird phenomena (something modern physics is quite good at). ---
**Author:** ![Polycarp](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Polycarp](https://boards.straightdope.com/u/Polycarp)\ **Post date:** [June 11, 2010, 1:08am UTC](https://boards.straightdope.com/t/what-is-light/542611/10 "2010-06-11T01:08:42Z")
FWIW, this is apparently basically commenting on [this staff report](http://www.straightdope.com/columns/read/2087/how-can-light-be-both-a-wave-and-a-particle) My take is, when someone says “quantum mechanics,” I look for **Chronos** or **Stranger** to answer it, because it’s certaub I have no clue. ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [June 11, 2010, 12:53pm UTC](https://boards.straightdope.com/t/what-is-light/542611/11 "2010-06-11T12:53:30Z")
> [@Xema](#): > > It’s strange that the best advice seems to be: Don’t try to understand - be content to accurately explain and predict all sorts of weird phenomena (something modern physics is quite good at). This is the main reason why quantum mechanics was so unpopular for so long. Science is supposed to be about understanding the world, right? Making sense of apparently odd phenomena, not making it more confusing. But, whether something _works_, and is therefore useful, turns out to be even more significant. So people shrug their shoulders and just get on with it. (Also of course, it does increase our knowledge of the universe, even if it doesn’t increase the amount of stuff we can intuitively grok.) ---
**Author:** ![Corner\_Case](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/corner_case/32/234_2.png) [@Corner\_Case](https://boards.straightdope.com/u/Corner_Case)\ **Post date:** [June 11, 2010, 6:31pm UTC](https://boards.straightdope.com/t/what-is-light/542611/12 "2010-06-11T18:31:15Z")
> [@Chronos](#): > > So, for instance, you might have the beam traveling in the X direction, the electric field in the Y direction, and the magnetic field in the Z direction. You might also have the beam in X, the electric in Z, and the magnetic in Y, or any angle in between. That angle is the polarization angle. is said in the linked column. Wouldn’t this represent two different types of light? If they propagated together both in X at the same time, but the second was rotated 90 degrees on X (Y to Z, Z to -Y), wouldn’t the electric fields cancel and the magnetic fields double? Kindof a magnetic monopole (no, this can’t be right!). If -90 the magnetic would cancel and the electric double? If I wave a bar magnet around, am I generating an electric field? And if I hold it still, where is the electric field component that goes with the magnetic field? For an electromagnetic wave am I right assuming that the the peak (trough) of the electric component coincides with the peak (trough) of the magnetic component at all times? If so, doesn’t this also mean that the components also momentarily become zero together halfway through each cycle (and effectively disappear)? ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [June 12, 2010, 9:03am UTC](https://boards.straightdope.com/t/what-is-light/542611/13 "2010-06-12T09:03:21Z")
> [@Corner\_Case](#): > > If I wave a bar magnet around, am I generating an electric field? And if I hold it still, where is the electric field component that goes with the magnetic field? There are no privileged reference frames, so although your magnet is still in your reference frame, it’s moving and creating an electrical field in all others.