I had this discussion today with my Network + Essentials teacher (kind of surprised me really...) and I just HAD to ask it here

Well, what is light? Light is made up of electrons that move at an insane speed of about 186,000 miles a second. Now, what EXACTLY is light all about?

Does light have mass? Some people I've talked to say yes. Some say no. Here's what I think: I tend to believe that light has SOME sort of mass in some way, as I believe electrons to have even a extremely microscopic amount of mass. Now, if you say yes (like me), here's some thoughts: If there is mass to light, why can't you contain it in a storage container that would not let light escape?

Ok, if you don't think light has mass, then think of this: If there is no mass to light, what causes it to bend when it passes an extremely strong source of gravity?

Everything is made up of atoms. Atoms and quarks are the building blocks of all materials. Electrons are made up of atoms as well. Now, take Gold for example. Gold is a pure element. Elements are made up of trillions of atoms. There are enough atoms there to make a substance have a noticeable amount of weight. In that case, since gold is made up of atoms (and everything else), then that proves that atoms have weight.

Weight contributes to mass.

Electrons are made of atoms.

Atoms=Electrons=Weight=Mass. Theoretically. Thus, light would have mass, right?

Maybe light is just that of pure energy. Maybe it's not really "there", so to speak. A pure energy souce and energy output by that source has no mass.

Then you get to thinking: Does your monitor get heavier when you turn it on, and electricity flows through it? Electricity is similar to light.

Or is light just how our mind percieves an energy source?

I'm not sure. That's why I asked.

well lets say it has mass...then you cant say u cant put it in a container. Coz light isnt just a ray you see coming from your flashlight, or the sun, its everywhere. So just passing a container through the air would technically entrap the light source within it because you can still see whats inside with the outside light source. That is why I do not really think it has a true mass. I think its more that light is sort of a concept we have created based upon many other factors that take place during the day, many other processes.

On my personal opinion now though, light is the devil!

If light has mass, and you put it in a container, how will you know if the light can't escape the container? You won't be able to see it if the light won't reach your eyes.

lol gtx.... ummm.. where do u come up with this stuff??

Um actually electrons are a part of atoms, atoms do not make up electrons

well as far as the "if it has mass it can be stored" thing, if it was stored in a container itd obviously have to be completely enclosed otherwise itd escape because well light keeps goin til it stops. I'd imagine if you were to open a container containing "light" itd just escape immediately and far too fast for our eyes to detect or anything for that matter. Wee see light because its continuous, a container of light would all escape together and it wouldnt be that much so itd be invisible to us or any equipment. This is all in theory of course.

the whole escaping thing, u cant really tell coz light is just everywhere, u cant just hold it up and see it inside the container, its already IN the container whether u like it or not .Just because light may not reach ur eyes and u cannot see it doesnt mean its not there. Its the same with anything, just coz u cant see it doesnt mean it doesnt exist.

Light does have a mass, but I'm not sure it always has. Actually, I think light is a combination of two things : the photons and the waves it creates. Actually, I think that what we see is the wave. But if you think this through, you will see that light HAS to have a mass. Think of black holes! Black holes do even attract light, you can see that because it's completely dark around dark holes. And one of the things you need to be attracted to a mass, is to be a mass yourself. As simple as that

Light does have mass and also its a particle and energy hmmm actualy the whole idea of matter is sort of misunderstood everything is energy... and light does not always move at 186,000 MPH thats only in empty space. for instance when moving through something like say a Ruby its about half that speed (takes time for the light wave to weave through the mass of the crystal) Thats the reason why lead crystal has such nice color seperation from "white" light all the colors are there and becouse its slowed down you see them refracted better. There is a realy nice book on the physics of light I have them in my Shareaza forlder do a search for these files. [eBook] - Science - Physics - Light and Matter Books.zip and LM Physics - Optics.pdf and Physics Of Color Perception.pdf realy interesting reading although I fear my lack of time precludes me from fully ingesting the information....

Fe=(9x10^9 = (k))(Q1)(Q2)/(d^2)) -> light has mass or a force of attraction and therefore mass. Although it may be very small it still exists.

I do believe this is the most intelligent conversation I’ve ever read/participated in (although I’m not participating much). This is very interesting and I’m not real sure whether I think it has mass or not because all of you make such good points I just can’t decide what I think. I agree that we don’t “see” it b/c it’s everywhere but I also think there has to be a way to find out b/c everything has a limits therefore there has to be some way to find out if it has a mass or not.

yes light has mass...corporal mass not weight coz its not the same thing. It takes up matter but its also ethereal at the same time, whether u believe it can be contained or not, really is up to you. Because if you go in the dark, the absense of light, you cannot see any more light in the container (if the container is transparent) then u could say u cant capture light. But maybe thats just coz our eyes cant pick up the light coz its so infinitely smaller. Besides, light is always there, you know how even in pitch black ur eyes adjust adn eventually you see something? Light is still present somehow. I think in a certain way it can be contained.

Whatever the answer might be..fluky is right...very very interesting

Light can be contained after a fashion... When light enters a black hole (the whole reason they are so hard to "see") it cannot escape. Although light has very little mass to it still a little is enough

yeah thats what i thought. However i was referring say if u took a glass jar and tried to catch some "light" with it.

If you made a sphear out of a perfectly 100% effecient mirror the light would bounce around for a long time but still would empty in time heheheh some particles of light actualy do time travel through some unkown mechanism they pick up an energy level and exceed the speed of light and pop out of this temporal existance (where they go dont ask me those books are actualy somewhat over my head) Although I think I read something about that light might actualy tap into zero point energy but thats a whole different Scientific question number 9 or something lol

Edit: On a side note this reminds me of a thing I forgot the name but its something to this effect if you put a cat in a box how do you know the cats in the box untill you observe it.

another thing I have thought about is this maybe the Light isnt picking up energy maybe its loosing it and the speed just under light couses time travel ? I dont know my brain is fried right now LOL

yeah i didnt quite follow that last one

i suggest you read this book, itz very interesting - 'A brief History of Time' by Stephen Hawking. He explains that light in some cases may have mass and in some cases not. Weird but true. It's something about light behaving differently at different times. You see, thats how light gets sucked into a black hole. If it had no mass, then it cannot be 'pulled' as such.

Also the part about electons=mass. Not true. You see, the mass of an electron, when compared to that of the atom is extremely small. So, the mass of an electon or several electons is negligible.

A little bit of newz i picked up : Scientists have managed to actually start and stop a beam of light. This was a year ago. Now, they have done it several times, and it could change comptuing the way we kno it

start and stop a beam of light? you mean...like have a controlled beam instead of it extending forward til it reaches a wall or object right?

So they can make light sabers now?

thats what i was thinking. BUt he said light. The question is can they restrict the beam of a laser to have a certain width and length and then control its power as well. Then yeah.

The thing about stopping light a year ago was a bit of a fiddle. They had caught light between two absorbers and emmitters in a very thin layer of a material (called a microcavity) so it kinda bouced about enough between the two to look stationary. It was fianlly done proply about 1 month ago but not entirely sure on the details.

In term of what light is it all depends on what your characteristic of light your measuring. Look up de broglie waves and youngs slits experiment That shows it behaves as a particle and hence has mass, whereas if you want to do some optical experiments you treat it as a wave and then it dont have mass.

Its a funny thing is light.

(ps as a particle it is called a boson and has a spin of 0 or 1)

Well, that's something I didn't understand either. Because in fact, the cat knows it dies. And then there's the mechanism that writes the letter, that one doesn't know the cat died, but it processed it, that's about the same thing. I've got the article right here, and it says the following : "In fact, before your brain processes the information, you have 2 possible states : A=cat's dead; B=cat's alive. But when you see it, the information is sent to your brain, and there something weird happens. These two states can't coexist, that would be a paradox. That forces your brain to choose for one of the two possibilities."
But I'd like to say that this is just a theory that is supposed to show that the reality is decided by measuring it (with our eyes for example). So this hypothetical. You could try to lock yourself up, but I doubt if you'd live forever

ok, this is way over my head!!

This all relates to quatum flux now what will realy blow your mind is this somethings are only the way they are becouse they are observed. Take for instance a single particle of light if you could see it, it would be gone and therefore you would have no way of proving you saw it.... realy anoying things quantum particles LOL

Edit: on a side note stopping light and making a light sabre would be two different things. If you stop a beam of light its stationary now for you to move a sabre about the light actualy has to move I would sugest some sort of plasma beam contained in an elongated magnetic field although using this thing would require no metals be around you LOL

ya, i agree with MS. even if you stop a beam of light it is only in a special container, not in thin air

The schrodingers cat phemomena was a thought experiment that forms part of a way of thinking about quantum phenomena called "The copenhagen interpretation"
(Name came from the city Neils bohr lived in)

He said that until you Observe an Atom or light it exists in both states (hence the alive/dead cat)

By 'observe' he means the transmission of information. so that can be by seeing it or by indirect measurements like leaving a device to detect it.

The crux of this is that until the measurment is made it does not really exist and is up there with the "falling tree in a woods does it make a sound"? question.

I was like you at 16 and dying to know these questions and one masters degree later I'm still none the wiser on the WHY this happens ;¬)

very good point