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Author Topic: Does Light Start Off Slow !!  (Read 2866 times)

Offline neilep

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Does Light Start Off Slow !!
« on: 04/07/2008 02:55:00 »
Dearest All,


Light is my all time favourite type of electromagnetic radiation of a wavelength that enables me to see stuff !

It's also well fast !.....even faster than my Toyota Previa..and that is fast !!!


Look here's some taking in a tour of Big Ben:



I hope it had the time to take in the full tour !


Anyway.....light travels at 186000 miles a second !..fast eh ?.....

...my question is...just before it starts off on it's journey does it start off slow and accelerate ?..and what propels it anyway ?


Thanks


Neil
Candle Owner


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Offline Soul Surfer

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Does Light Start Off Slow !!
« Reply #1 on: 04/07/2008 09:44:00 »
The classical description of light is as a wave motion in the electromagnetic field ans waves always travel at the wave velocity because they just cant stand stil think of it coming out as a series of ups and downs.  The quantum mechanical description as a particle only overlays this because it aleays has a wavelength and other properties of a wave the particles mean the waves just come a sets.  Ask ant surfer and they will tell you what a set is.  Once they have settled down waves always tend to travel in litle groups it is only on very rare occasions that you get a solitary wave or soliton
 

Offline Alan McDougall

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Does Light Start Off Slow !!
« Reply #2 on: 04/07/2008 17:24:59 »
Light does not accelerate it can only move at C light speed in a vacuum of course,
 

Offline neilep

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Does Light Start Off Slow !!
« Reply #3 on: 04/07/2008 19:09:39 »
Thank you both Ian and Alan,

It is difficult for a laymans' layman ,like myself ,to comprehend how something that is shown to travel at a speed did not have to start from a starting point and then accelerate to C.

Thank you for your insightful assistance !
 

Offline Flyberius

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Does Light Start Off Slow !!
« Reply #4 on: 09/07/2008 00:53:43 »
I know how to answer this one.

Think of the aforementioned "electromagnetic field" as a rowdy stadium of football supporters.  Think of light as a mexican wave.  When an energetic particle (in this case a merry supporter) gains the energy to pop of a photon he jumps in the air and the person next to him instantly jumps as soon as he sees it, arms flailing en all. The mexican wave has begun and travels at a constant velocity but didnt actually need to accelerate because no person is actually moving in the direction of the wave.  You arent measuring the speed of an object in a strait line, you are measuring the peaks of an effect, or in this case a crowd of drunk, angry lads.
 

Offline syhprum

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Does Light Start Off Slow !!
« Reply #5 on: 09/07/2008 13:43:04 »
When electromagnetic radiation leaves an antenna it takes half a cycle for the magnetic and electrical components to settle into their correct phase relationship, something similar must happen with light.
 

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Does Light Start Off Slow !!
« Reply #5 on: 09/07/2008 13:43:04 »

 

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