what propels light?

[yusufcam (Colin)]

a quick question....(har)

just reading something about electromagnetic radiation and wondered..
(have limited internet access, so i posted here)

light is in motion, light source is stationary, why is light propelled at such speeds...

if it is a substance how does it reach such speeds and not ever slow and why is that then the limit of speed?

[GeoffW1 (Geoff)]

Hi,

A good question which attracts interest because the detailed rigorous science of it is so obscure to most of us

Firstly (as I understand it) the speed of light as an absolute is an intrinsic property of space-time. It is the natural and inevitable speed of other types of elementary particle besides the photon, for instance bosons.

Prof Brian Cox (calm, calm, ladies) has co-written a terrific book which has in it the most simple and elegant explanation of why c is such a basic property of space-time, "Why does e=mc^2 and why should we care". It is really worth a read.

These quasi-particles are "mediators" of different fields, that is, they make the fields known and felt to us. The photon is the mediator of all kinds of electromagnetic field effects. The undiscovered graviton would be the mediator of gravitational fields, if we could find one

Photons are without any mass at rest, so have no inertia, and then need no force to push them along to c. That speed is actually their natural state, in a vacuum anyway (they go slower in a housebrick). Indeed they are really only spoken of as particles at all because they behave that way in certain circumstances. At other times they behave as a wave. This is one of the planks (no pun) of Quantum Theory.

I've given myself a headache now, so I'll leave the rest to some real experts.

Cheers

[ballaratdragons (Ken)]

Great questions Colin

I await the answers with you.

[mswhin63 (Malcolm)]

I think light does not accelerates instead reaches it required speed because of its massless condition.
The term photon was given because of the way it interacts with matter (bending, relection speed limit etc) but it real nature is Electro-Magnetic radiation ie. radiation that come from a source (Supernova, energy release from a source including Radio, Gamma rays etc). Electromagnetic radiation is the key to understand lights real nature.
Correct me if I am wrong.

[avandonk]

This is a non sensible question. The OP is obviously deluded at best or a troll at worst.

He only needs to study some science to get an answer to this idiotic premise.


There are reams of information that is easily accessed by google.

Bert

[avandonk]

Originally Posted by GeoffW1

Your bile duct playing up today Bert?

I just get angry when ignorant idiots cannot understand basic physics.

There is a lot of this about where you lead the ignorant public with nonsense science.

My bools_s_h_i_t alarm went off!

Bert

[avandonk]

Colin you do not exist! You are just the interaction of EM particles that constantly produce you. What is even more amazing is that you live on a rather large rock orbiting a rather large star. All this is made of the same stuff!

There are far larger stars around here somewhere. The death of these stars made the nuclei that you are made of eons ago.

If I was wrong I apologise. I do not think so, as no one can be so ignorant as you portray. Unless you just crawled out from under a rock from the proverbial primeval slime.

Bert

[GeoffW1 (Geoff)]

Originally Posted by avandonk

Colin you do not exist! You are just the interaction of EM particles that constantly produce you. What is even more amazing is that you live on a rather large rock orbiting a rather large star. All this is made of the same stuff!

There are far larger stars around here somewhere. The death of these stars made the nuclei that you are made of eons ago.

If I was wrong I apologise. I do not think so, as no one can be so ignorant as you portray. Unless you just crawled out from under a rock from the proverbial primeval slime.

Bert

OMG Bert take it easy, you will have a stroke

[traveller (Bo)]

Whoa Bert, strong words there. There might be a chance its an innocent question, just because we have an interest in astronomy doesnt make us all astrophysicists.
Bo

[GeoffW1 (Geoff)]

I's not too serious I believe

[avandonk]

In my defense I put it to the jury that lately many false and dare I say it liars are doubting well established science.

I am very calm and calculating. You have no idea how icy I can treat ignorant idiots. I have no intrinsic bad feeling for ignorant idiots. It is only when they pass themselves off as experts that I get a tad testy.

Bert

[ballaratdragons (Ken)]

and here I was waiting to see if anyone would give a really short simple answer to one of the most fascinating aspects of science, so I could copy it and say I know everything

[avandonk]

Originally Posted by ballaratdragons

and here I was waiting to see if anyone would give a really short simple answer to one of the most fascinating aspects of science, so I could copy it and say I know everything

OK ken here we go.

Reality does not rely on matter. It is the space time fabric that is our Universe. Even where there is nothing virtual particles appear and disappear.

Time could be based on the mere interaction of even virtual particles. Without interaction there is no time. When the interactions stop, time will cease.

The fact that we all exist to even ask these questions is improbable to say the least.

I could go deeper with lots of equations but that will not explain anything.

Our real understanding is just beginning.


Bert

[casstony]

Now you're just being condescending Bert - of course we know dat stuff

[Dave2042 (Dave)]

Here's my 2 cents' worth.

I don't think it's a foolish question at all. On the face of it, if light is a particle, why shouldn't it need to be set off in motion by some force like any other particle?

I think the real answer is to see that this is actually a specific version of a very general question: what is really going on with phenomenon X?

As I think I've observed in other threads, while this is a reasonable question to ask of physics, it's a question that physics gave up on trying to answer along time ago. The best physics can do is come up with equations that well describe observable quantities.

Particularly since the advent of quantum mechanics and relativity (both involved in the question asked), the underlying processes are so removed from our day-to-day reality, that a 'sensible' explanation corresponding to our day-to-day reality seems a hopeless task.

So, I think the answer to the question posed is not much more than this. Light just travels at the speed of light, with nothing 'starting it off' - that's just how light is, and if it doesn't make sense then it doesn't make sense.

[yusufcam (Colin)]

interesting....

thought i'd ask in case there was a simple answer, no real motive other than that.

just came back from the illawara air show, plenty of light (sunshine) propelled down there today, thats for sure (forgot to take a hat).

wow, those old piston engine planes make the most interesting sounds (like four cycylinder harleys through a rock concert some noted).

a good day (missed the steamfest, last week).

anyway thanks

[Peter Ward]

Originally Posted by avandonk

....

I could go deeper with lots of equations but that will not explain anything.

Our real understanding is just beginning.


Bert

Oh! Oh! I have a question.

Electron changes valence levels....and emits a photon. Paul Dirac had a lot to say about that.

What has me stumped is: what is the mechanism? Why do electrons do that? Is it simply enough to say, well, they just do.

Which leads me to my next question: condsider E=cv (energy of a photon is directional proportional to its frequency )

Where did all the energy of the (very high frequency) photons from the big-bang go? since they have apparently now cooled to very low frequency in the CBR !!!

[bartman (Bart)]

Originally Posted by yusufcam

light is in motion, light source is stationary, why is light propelled at such speeds...

Dark energy draws ( sucks) them along?.............


Bartman

[Jaybee (John)]

Originally Posted by avandonk

In my defense I put it to the jury that lately many false and dare I say it liars are doubting well established science.

I am very calm and calculating. You have no idea how icy I can treat ignorant idiots. I have no intrinsic bad feeling for ignorant idiots. It is only when they pass themselves off as experts that I get a tad testy.

Bert

Geez Bert
Its a good job Colin didn't ask you in person you would have taken his head off with a single strike! It was just a simple question and he said he had limited internet access, so google may not have been an option...This ignorant idiot also wouldn't have minded a simple answer in simple terms, as clearly I'm simple, because I couldn't follow your replys at all except to know they where rather scathing and personal. I re-read Colins question and sorry, I didn't get the feeling that he was trying to pass himself off as an expert, I re-read it again and I couldn't find the bit where he slammed the publishings of established science...I guess I am just too trusting as I thought that it was a genuine question, still do by the way, and even if it wasn't, wouldn't a well thought out answer have been better and more helpful, even if only to younger less seasoned readers, than an angry tirade?? just my 2 cents...please don't hurt me..

[marki]

Here you go, not my words

"From the source, light travels in all directions. To understand how it travels, let us consider a ray of light travelling on a rectilinear path and see what all phenomena occur on that path.

At a definite instant of time, at various points on the path of propagation of light, there are electric intensity vectors in a plane perpendicular to the path of propagation of light ray. Their magnitudes at various points are such that their tips when joined form a wave. At the same instant, there is a similar looking magnetic intensity wave in a plane perpendicular to the plane of the electric intensity vectors and also to the path of propagation of the light ray. Beyond some distance from the source, both these waves are in phase.

After an extremely small time interval, if we again join the tips of the intensity vectors, we get a new wave similar to the previous one but slightly displaced in the direction of light propagation. Thus light travels in the form of an electromagnetic wave. We discussed light propagation on a rectilinear path, but it travels in all directions from the in the same way reaching the surface of a sphere of radius equal to the distance travelled by light if the medium is homogeneous".

Gotta love physics

Mark