The shape of light

[cpwmatthews]

It's 5am and I've spent all night woundering about the shape of light.

I 've decided that it COULD be a disk that when travelling forward gets an indent to it's centre making it a small cone from where the light emminates. this may explain why you cannot see a beam of light from any angle other than from the front, unless it contacts with a medium say a gass or solid object.

Any thoughts??

[dirtyamerica]

Are you suggesting that photons are disc shaped?

[cpwmatthews]

Forgive me if I seem a bit dim but I point out that it is merely my hypothosis that static photons begin disk shaped then immediately go conical upon travell and as light is always travelling fast they in a way would never really be discs.

[mooeypoo]

I was looking for some resources online about the shape of photons, and came up with this:

https://www.icfo.es/images/publications/J05-040.pdf

 

I can barely make out anything, this is waaaaaay over my head in scientific specifications... but perhaps someone can make somethin gout of it? I think I've heard somewhere that it was possible to "film" or "look" at a single photon. If that's true, then its possible to get a "shape".

 

I'm... guessing here? Err. This is just very interresting indeed. Would love to know if there actually is a hypothesized shape for a photon.

 

~moo

[cpwmatthews]

Thans for the web site to look at, the maths is way beyond me too and quite what "entangled photons" are only the enlightened ( no pun intended ) can say. I thought the images of light were very near to what I propose as they appear to show what would be the end of the cone shape I was trying to get accross.

As I said in my initial question, you can't see photons side on unless they collide with some matter and then I proffer that you see them then because their motion path has been reversed. Any thoughts??

I've gone back to the Acrobat Reader piece and the maths seem all about angles of photons rather than our immediate question about shape, and I wa sthinking again about what it said about "entangled" which I now presume to be caused from photon collisions. I envisage colliding photons as merging together rather than bouncing off each other because the photon does not possess any solid state from which to bounce??/?

[mooeypoo]

Basically, from what I learned about light, the only reason you see it when its "colliding with matter" is because it's bouncing back to your eyes. If you use a matter that absorbs the light, you won't see it even as it collides with it.

 

Light is also said to be both wave and "matter". From what I remember from my physics lessons, it's quite the debate. I think today science just "agrees" to call it both.

 

Hope I'm not wrong with this... learnt it quite generally (relatively) and quite a while ago.

 

~moo

[cpwmatthews]

Yes thats what I think although less so that light has "matter"

[TimbaLanD]

Basically, from what I learned about light, the only reason you see it when its "colliding with matter" is because it's bouncing back to your eyes.~moo

 

Does this mean light is capable of carrying an image? When the photon enters the eye, it’s still only a photon. What makes it different from any other photon?? Surely all photons are identical yet we see different images!! HOW HOW HOW??? WHY WHY???

[mooeypoo]

what what whaaaat?

 

No.. I lost you completely..

 

Light bounces off surfaces and enters your eyes. Various "intensities" and wavelengths determine colors. Colors build up pictures that your brain interpret. Changin in those pictures, movements, are interpreted in your brain and you see your invironment.

 

This is not "Photon", it's Photons (plural). Many many many photons..

 

Photons are not quite "identical", they differ in intensity. They're "packets of energy". Different Energy/Intensity = different input your brain interprets.

 

This is also why light is dual -- both wave and "matter" -- wavelengths are used to explain different colors. But light also has very "weird" behaviour in terms of emmitting energy; so it is explained as behaving as a "matter"(or 'enery', actually) together.

 

This is out of my limited knowledge. I didn't really understand your question though.. did I even answer it?

 

~moo

[MattC]

Light is often called electromagnetic radiation because it travels as a wave in the electric and magnetic fields. I am hardly an expert, but I don't believe it has a shape in the sense that you might expect. Rather, imagine that a ball is moving in a straight path, and that as it moves it affects electric and magnetic fields around it, creating a wave in the fields (as it moves). Now imagine that there is no ball, just a point, traveling in a line, at which the electric and magnetic fields are affected. This wave in the electromagnetic field is light. When it hits something, it interacts as though it is a particle, but while traveling it behaves as a wave.

 

As for seeing a photon from the side ... or seeing a photon at all:

 

When you see something moving past you, such as a bullet, you are not seeing the bullet itself - rather, light is coming from somewhere (sun, lights in a building, whatever) and hitting the bullet. Some of that light bounces off and goes straight for your eyes, where it hits your eyes. Different colors represent different frequencies of the light, though different colors (as well as heat itself, and UV radiation, radio waves, and quite a bit more) are all fundamentally the same - light.

 

A photon is what you see, when it hits your eyes. So you cannot "see" a photon unless it hits your eyes. If a photon is speeding by, in front of you, then it doesn't hit your eyes ... it just goes past you. So you don't see it with your eyes.

 

An image is formed by a bunch of light hitting an observer or appearing to come from a particular place or ... well, there's a lot to learn about imagines, some are real and others are virtual, and it's difficult to explain. Much better to google it and look for some pictures.

[TimbaLanD]

Yes, you have answered my question!! “Light bounces off surfaces and enters your eyes. Various "intensities" and wavelengths determine colours. Colours build up pictures that your brain interprets. Changing in those pictures, movements are interpreted in your brain and you see your environment”

 

That makes sense… The amount of processing that a brain have to do to see something is amazing!

[mooeypoo]

indeed, our brain is complex.

 

Check these out:

 

http://www.unitn.it/convegni/download/neuroscienze/Perret.pdf

 

and, though a bit "general", it is a good site to learn the basics of light behaviour (and colors in specific):

http://science.howstuffworks.com/light6.htm

 

~moo

[cpwmatthews]

I do believe light has a shape even though you must agree that most uniform things in the universe are round, that is not to say I believe photons are round because then light would emminate from the globe in all directions, it does not. Otherwise when you shine a torch in one direction the light would also shine back on itself,it does not. Therefore light or many many photons travell one way and only shine back when they hit something.

Yes you see light when it hits you in the eyes and as was said by Moo it's the wave lengths that make the colour but even as atomic structure has shape I say I believe a photon has shape too and it's conical in a vary small way.

[mooeypoo]

actually, I'm not sure about the "everything in the universe is spherecal" declaration thing.

 

First off, not quite; planets are oval usually..

 

Second, I must wonder about atoms too.. Are they truely "Round" the way they're depicted in the drawings, or is this just the way we chose to represent them?

 

And isn't a sphere the most "perfect" shape in 3 Dimentions? Perhaps things are "more" than a sphere when you go up to more than 3 dimentions, but since those are what we percieve with our brain, we make out everything that has a shape beyond that to be a sphere.

 

Much like beatles; they percieve 2 dimentions, and when encountering a "hole" or a "bump" they don't actually see it.. their brains translate it as something the can understand in their own 2-D perception...

 

~moo

[cpwmatthews]

ok not truely round but you must agree roundish is the norm for most things that hold themselves together otherwise bits would blow off

[mooeypoo]

I'm not sure light even HAS a shape. If it isn't matter, it's energy, odds are it's "abstract" in its form.

 

Or.. at least I'd think it is :\

 

I really should go over my physics ...

 

~moo

[cpwmatthews]

a spark is energy and sparks have a kind of shape usualy like a bar pointing to its nearest contact so why not alow yourself to think of light photons in terms of shape. If they were amorphus they would be too random and light is too regular in my view

[Klaynos]

light would emminate from the globe in all directions

 

The photon IS light and the only direction it can travel is the direction of motion of the photon.

 

Otherwise when you shine a torch in one direction the light would also shine back on itself

 

That's why torches have mirriors in them to direct the light out through the lens. The only way you can see stuff using a torch is because the torch light bounces back from objects int your eye.

 

Photons are wave-particles, they are a deformation in the electromagnetic fields. The Fields are orthoginal to each other, and the direction of motion of the photon is orthoginal to both of these fields.

 

I always "picture" photons as being two sin waves orthoginal to each other, in an elipse kind of shame (which is kinda wrong). Photons don't really have a shape as far as we know.

 

The reason lots of stuff is round is becuase there are alot of fields (gravity being one) that are spherically symetric. The reason plannets are not perfectly spherical is that they are deformed by the fact they're spinning.

 

And now the final point I'd like to make on entanglement, entanglement is a quantum phenomenon in which two wave-particles are made to have some characteristics that when measured on one of the pair the characteristics of the other one are instantly known, no matter what superposition state they where in...

[swansont]

I do believe light has a shape even though you must agree that most uniform things in the universe are round' date=' that is not to say I believe photons are round because then light would emminate from the globe in all directions, it does not. Otherwise when you shine a torch in one direction the light would also shine back on itself,it does not. Therefore light or many many photons travell one way and only shine back when they hit something.

Yes you see light when it hits you in the eyes and as was said by Moo it's the wave lengths that make the colour but even as atomic structure has shape I say I believe a photon has shape too and it's conical in a vary small way.[/quote']

 

Light from a point source does emanate in all directions. Even from a torch/flashlight, which is generally why you put a reflector in it.

 

Just because you don't see photons going in the other directions doesn't mean they are not there.

 

The shape of a photon is an ill-defined issue in the context being described here. They are whatever "shape" the wave function has.

[Severian]

It's 5am and I've spent all night woundering about the shape of light.

 

A more interesting question might be 'what does light smell like?'.

[mooeypoo]

Great question!! What does it smell like really?

 

 

 

 

And, uhm cpwmatthews, I would suggest you go read a bit about light and it's behaviour.. it seems you got a few basic points slightly wrong, and it seems to confuse you.

 

~moo

[jgmaynard]

The wave/particle thing happens (IIRC) because if you test to see whether it is a wave, it is a wave; if you test whether it is a particle, it is a particle. So, logically, it either has to be both (currently accepted) or something else (I have a feeling this will turn out to be the answer).

The shape, though, is an interesting question. My instinct is to say it can't have a shape, but I don't know why. My first thoughts are that if the photon were "confined" within a certain shape, and the object HAD to travel at local c., then the size would have to become enormous to maintain the Heisenburg U.P. Since that size is limited by local c., I think the "shape" we assumed at the beginning would have to give.

But that is just a SWAG and I make no assurance of fact whatsoever.

 

JM

[SmallIsPower]

Good Question! I read light is a wave/particle as a kid, and never once thought of it having a shape. Perhaps it's hyperdimenssional, giving us a hard time describing it in space/time.

[the tree]

And, uhm cpwmatthews, I would suggest you go read a bit about light and it's behaviour.. it seems you got a few basic points slightly wrong, and it seems to confuse you.

On the Discworld (the Universe of Terry Pratchetts major fantasy series), there are two types of light. There is the "slow light" which rolls over the hills and hovers near windows in a dusty room, then there is the "fast light", this is what lets you see the "slow light".

That's what the OP reminded me of.

[gcol]

Perhaps consider a photon as an envelope with a fuzzy outline. Its shape depends upon your power of resolution? (How far from the theoretical "centre" you measure its peripheral uncertainty effects). From the side, would it not look like a sort of sinusoidal envelope whose length depends upon observation time?