# What is light made of?

by seminole
Tags: light
 P: 6 Hey is light made of electrons or protons? I know that all matter in existence is made up of a combination of those two. I figure it is one of each that way that the total charge is 0 and it's all neutral and stuff (and due to the symmetry of the universe and all that) but i'm not sure. I tried to look it up but it wasn't really clear it said online that it was a photon but I know that's just a sci-fi kind of term (that they use in Star Trek and stuff). So can anyone clear this up?
 P: 560 http://science.howstuffworks.com/light1.htm If you don't find your answer there, let me know.
P: 6
 Quote by dontdisturbmycircles http://science.howstuffworks.com/light1.htm If you don't find your answer there, let me know.
Hello! Thank you for the link, it is very informative but it does not answer the problem regarding the proton and electron but instead gives a vague answer in terms of this imaginary "photon". Please clarify! Thanks! :)

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## What is light made of?

 Quote by seminole Hey is light made of electrons or protons?
no.
 I know that all matter in existence is made up of a combination of those two.
that's not quite true, either.
 I figure it is one of each that way that the total charge is 0 and it's all neutral and stuff (and due to the symmetry of the universe and all that) but i'm not sure. I tried to look it up but it wasn't really clear it said online that it was a photon but I know that's just a sci-fi kind of term (that they use in Star Trek and stuff). So can anyone clear this up?
probably not.

if i were to say light (visible light is just particular frequencies of the electromagnetic spectrum) was "made from something", i guess i would say it is made from varying (and propagating) electromagnetic fields.
 P: 560 lol. I am pretty sure you're confused :) The photon is for real! A proton is a particle in an atom which does have mass (And could never travel at the speed of light) , a photon what light is made of (and is massless, thus it can travel at the speed of light). edit: By the way my answer was directed to OP. rbj snuck a post in before me :). btw rbj's post is more accurate then mine.
P: 6
 Quote by dontdisturbmycircles lol. I am pretty sure you're confused :) The photon is for real! A proton is a particle in an atom which does have mass (And could never travel at the speed of light) , a photon what light is made of (and is massless, thus it can travel at the speed of light). edit: By the way my answer was directed to OP. rbj snuck a post in before me :). btw rbj's post is more accurate then mine.
Sorry but this explanation doesn't seem quite right since protons and electrons are the basic building blocks of matter and can't be made of anything else (proton has a charge +1 and electrons -1, thus you can't have anything else since what would it be? The only other thing is neutral which is 1 p and 1 e and that is my theory of what light is). The notion of light being waves seems pretty silly (after all, when you turn the lights off they dont slowly ripple away like a stone dropped in a pond) so I don't know where that came from. Light is definitely a particle that is a proton/electron mixture but I don't know what that exact mixture is.
 P: 555 1) Protons and electrons are not the building blocks of all matter. 2) The notion of light being a wave is not silly. Your idea that waves slowly ripple off after you stop them or something, and comparing that to light, is silly. 3) Light is massless. Protons and electrons have mass.
 P: 560 $$m=\frac{m_{o}}{\sqrt{1-\frac{v^{2}}{c^{2}}}}$$ where m = mass v=velocity c=speed of light (299 792 458 m / s ) $$m_{o}$$=rest mass Since I am sure you would agree that protons and electrons both have mass (if you don't, you are OBVIOUSLY trolling), it becomes apparent that the mass of any object comprised of protons/electrons becomes infinitely great as the object approaches the speed of light. According to that equation which you can read more about here http://en.wikipedia.org/wiki/Relativistic_mass light can't possibly be made of protons or electrons. Plus you are leaving out many many many many subatomic particles that make up the universe. Anyways, hopefully that site helps you, but my true suggestion is for you to pick up a physics book and read if you're interested.
Mentor
P: 11,239
 Quote by seminole Sorry but this explanation doesn't seem quite right since protons and electrons are the basic building blocks of matter and can't be made of anything else (proton has a charge +1 and electrons -1, thus you can't have anything else since what would it be?
Electrons are indeed one of the fundamental particles (building blocks, if you like), but protons are not. Protons are made up of quarks and gluons. So are neutrons, which you also find in an atomic nucleus.

 The only other thing is neutral which is 1 p and 1 e and that is my theory of what light is). The notion of light being waves seems pretty silly (after all, when you turn the lights off they dont slowly ripple away like a stone dropped in a pond)
Light waves travel at a speed of $3 \times 10^8$ meters per second, so they do "ripple away" but so very very rapidly that it looks like they disappear instantly.

 so I don't know where that came from.
Light has wavelike properties because it exhibits diffraction and interference, which are impossible with purely particle-like objects.

 Light is definitely a particle that is a proton/electron mixture but I don't know what that exact mixture is.
Light also has some particle-like properties, but it's definitely not a proton/electron mixture. For a summary of the current state of generally accepted knowledge/theory about particles in general, try

 P: 684 jtBell gave the correct answers and said them very concisely and nicely. If you then ask what a photon is, no one can answer that question because its considered indivisible just like a quark or electron or graviton is. These 4 particles are called fundamental particles and its thought that everything in the Universe is made up of them. P.S.What's trolling mean?
 Mentor P: 7,292 I am keeping a pretty tight fist on this thread. If you have had a post vanish, very likely it addressed the sincerity of the OP rather then making a effort to answer his question. At this point there are several good explanations, it is now up to the OP. Seminole: You need to read the remaining posts very carefully. They contain good information.
P: 94
 Quote by dontdisturbmycircles Since I am sure you would agree that protons and electrons both have mass (if you don't, you are OBVIOUSLY trolling), it becomes apparent that the mass of any object comprised of protons/electrons becomes infinitely great as the object approaches the speed of light.
Since when did photons have mass???

They are just blocks of pre-packaged energy, and energy does not have mass.
 PF Gold P: 8,961 Mad, if your response is to the section that you quoted, I think that you misread it. It says protons and electrons, not photons and electrons, and the relativistic mass gain is real. Integral, I have no issue with the sincerity of the original question, but the refusal to accept correct answers is a bit irritating. Seminole, I don't know where you ever got the idea that photons are fictional. They are the quanta of electromagnetic radiation, which is indeed composed of an electric field and a magnetic field oscillating perpendicular to each other. Light displays the characteristics of both a wave and a particle. Which one it seems to be at any particular time depends upon how it is observed. (Compare the dual-slit experiment with the photoelectric effect.)
P: 2,265
 Quote by MadScientist 1000 Since when did photons have mass???
oh, i guess since energy was discovered to be equivalent to mass.

 They are just blocks of pre-packaged energy, and energy does not have mass.
there is a serious proposal to redefine the kilogram in such a way as to define Planck's constant to a fixed value (rather than measure it, similarly to how the meter was redefined so that the speed of light is defined to be 299792458 m/s). one such wording is:

The kilogram is the mass of a body at rest whose equivalent energy is equal to the sum of energies of a collection of photons whose frequencies sum to exactly (2997924582/66260693 x 1043) Hz.

so if we could put that collection of these blocks of pre-packaged energy in a perfectly mirrored box of neglegible weight on one platter of an honest scale and put the kilogram prototype on the other platter, which way does the scale tip?

photons have mass. the mass of a photon is

$$m = \frac{E}{c^2} = \frac{h \nu}{c^2}$$

but because

$$m_0 = m \sqrt{1 - \frac{v^2}{c^2}}$$

the rest mass is zero because the speed of photons are normally believed to be the same as the wavespeed of light (which is $c$).

photons have mass (inertial mass, what you get when you divide momentum by velocity), but no rest mass or "invariant mass".