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Author Topic: What is the driving force behind photons?  (Read 34720 times)

manjit

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What is the driving force behind photons?
« on: 25/09/2008 08:03:01 »
Hi All!

I wonder if some sharp heads can explain what is the driving force behind the movement of electromagnetic radiation - why does light move - if it does. Does light use some energy to move it self or it does not move any resistance?

Thanks!

Manjit

<Mod edit - Formatted the subject as a question - please do this to help keep the forum tidy and easy to navigate - thanks!>
« Last Edit: 25/09/2008 12:53:16 by BenV »

manjit

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What is the driving force behind photons?
« Reply #1 on: 27/09/2008 07:59:37 »
A little correction

Hi All!

"Does light use some energy to move it self or it does not move any resistance?"
There should be:- Does light use some form of energy to move it self or it does not meet any resistance in the space.

Thanks!

Manjit

DoctorBeaver

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What is the driving force behind photons?
« Reply #2 on: 27/09/2008 09:01:13 »
I think you mean "What gives a photon its velocity?". Unfortunately, I cannot provide an answer.

chris

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What is the driving force behind photons?
« Reply #3 on: 27/09/2008 09:33:48 »
Light is electromagnetic (EM) radiation; put simply this is a changing electrical field which induces a changing magnetic field which in turn produces a changing electric field, and so on. This field propagates from the source like ripples on a pond. There's nothing at ehe edges of the pond pulling the ripples towards it, they move there because this is the way to maximally disperse the energy that caused the ripple in the first place.

So these ripples spread out from their point of origin; it's the same with a radio transmitter. At the ripple source there is a lot of energy in this one place which is dispersed as the waves move further from the source because the energy is effectively being spread over a larger volume of space. This is why the inverse square law applies; that is, if you double the distance the energy falls to 1/4 of what it was previously.

Chris
« Last Edit: 27/09/2008 21:49:21 by chris »

DarthTutor

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What is the driving force behind photons?
« Reply #4 on: 27/09/2008 22:29:20 »
The speed of photons is dictated by the geometry of spacetime. All waves in the vacuum (when left to their own devices and not interacting with matter or any other fields) will travel at one and the same speed "c". This is a fundamental constant of nature that has a geometric origin in the fact that space and time together form a single continuum called spacetime. For this to be possible some fundamental constant, "c", should allow the conversion of length units into time units. This c has the units of speed.

DoctorBeaver

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What is the driving force behind photons?
« Reply #5 on: 28/09/2008 08:14:15 »
Could c be different if spacetime were dramatically curved or warped? I'm thinkng of some of the extra-dimensional models such as RS2.

manjit

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What is the driving force behind photons?
« Reply #6 on: 28/09/2008 20:01:16 »
Thank you evreybody who has taken some moments to put forth some thoughts in relation to my post!

I just wanted let it be known that I do not have any formal education in physics. Also my english is not very good. Anyway I do have burning interest in some basic natural phenomons. So I hope that every body much more educated than me in these subjects would not mind me posting some questions here in hope to learn more about the nature and hopefully also contribute to the forum afterwhile.


I think you mean "What gives a photon its velocity?". Unfortunately, I cannot provide an answer.
. Thank you! That is what I ment.

Chris I understand that photons are changing magnetic and electric field. But here I also wonder:- Electric field in the first place originate from electrons. When we think about EM radiation propagating through vacuum, there is no electron in the vacuum - or there shoud not be. So how is the electric field generated there?

After reading these valuable posts I now think that there must be some pushing force between the different photons, even consisting of the same frequency. Do photons consist of both north and south magnetic pole? I believe they should. Does electric field have any polarity?

In simple words, the space for me is something related to volume and time is related to some sort of change in a given system, for example the relative laction of the sun or some other process. Can someone please throw some more light on it and also on spacetime?

Many thanks for any thoughts!

manjit


JukriS

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What is the driving force behind photons?
« Reply #7 on: 29/09/2008 05:20:16 »
Hi All!

I wonder if some sharp heads can explain what is the driving force behind the movement of electromagnetic radiation - why does light move - if it does. Does light use some energy to move it self or it does not move any resistance?

Thanks!

Manjit

<Mod edit - Formatted the subject as a question - please do this to help keep the forum tidy and easy to navigate - thanks!>

There is only one driving force for everything. It is energy who changing to not so density energy!

LeeE

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What is the driving force behind photons?
« Reply #8 on: 29/09/2008 11:16:38 »
Quote
There is only one driving force for everything. It is energy who changing to not so density energy!

I think JukriS may be referring to entropy here.

LeeE

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What is the driving force behind photons?
« Reply #9 on: 29/09/2008 11:41:22 »
Could c be different if spacetime were dramatically curved or warped? I'm thinkng of some of the extra-dimensional models such as RS2.

I guess it could be but I suspect that 'c' is always the same within it's space-time frame, although that space-time frame could be distorted and, when viewed by a distant observer, could appear to be different.  For example, if we could somehow distort a 1x1x1km volume of spacetime so that it fitted in to a 0.5x0.5x0.5km volume of space and then consider a photon of light passing from 'normal' space, through the 'compressed' region and then back into normal space, to a distant observer the distorted region of space would only appear to be 0.5 km across and light would seem to slow down when it traverses it.  The photon of light itself, however, has actually had to travel a full 1km of distance to cross the 0.5km gap between the two regions of 'normal' space.

This would be akin to the pair of clocks that end up recording different periods of time when one is moving and the other is not except that the two differing viewpoints record a different distance instead of time.

labview1958

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What is the driving force behind photons?
« Reply #10 on: 21/11/2008 00:08:37 »
Could it be that the photons are travelling into the future. The photons disappear and reappear every nanosecond. Thus the photons are stationary. Only space moves. To us it is as the light is moving.

lyner

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What is the driving force behind photons?
« Reply #11 on: 22/11/2008 16:45:23 »
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Thus the photons are stationary. Only space moves.
Bearing in mind that photons are moving in all directions, which direction is all of space moving`?

that mad man

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What is the driving force behind photons?
« Reply #12 on: 22/11/2008 17:28:44 »
Propagated by gravity waves that travel in a similar manner to background radiation, travelling at C and moving in all directions.



lyner

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What is the driving force behind photons?
« Reply #13 on: 23/11/2008 00:02:16 »
What does 'movement' actually mean in that context?
It does not seem to fit in with the accepted meaning so are you rewriting absolutely everything?

that mad man

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What is the driving force behind photons?
« Reply #14 on: 24/11/2008 18:06:21 »
Quite right, I should probably have said a constant forward velocity C, and acting in a similar way to background radiation.


DoctorBeaver

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What is the driving force behind photons?
« Reply #15 on: 25/11/2008 17:14:43 »
Could c be different if spacetime were dramatically curved or warped? I'm thinkng of some of the extra-dimensional models such as RS2.

I guess it could be but I suspect that 'c' is always the same within it's space-time frame, although that space-time frame could be distorted and, when viewed by a distant observer, could appear to be different.  For example, if we could somehow distort a 1x1x1km volume of spacetime so that it fitted in to a 0.5x0.5x0.5km volume of space and then consider a photon of light passing from 'normal' space, through the 'compressed' region and then back into normal space, to a distant observer the distorted region of space would only appear to be 0.5 km across and light would seem to slow down when it traverses it.  The photon of light itself, however, has actually had to travel a full 1km of distance to cross the 0.5km gap between the two regions of 'normal' space.

This would be akin to the pair of clocks that end up recording different periods of time when one is moving and the other is not except that the two differing viewpoints record a different distance instead of time.

That's compression, not warping. Warping involves every point in an area of spacetime being curved in n dimensions. An analogy would be the bell of a trumpet.

On a more technical note, the difference between warping and curvature is that every slice through a warped spacetime has the same geometry; that is not so with curvature.

LeeE

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What is the driving force behind photons?
« Reply #16 on: 25/11/2008 19:17:34 »
The only difference I can see between compression and warping is when the compression is linear across a region.  If the degree of compression changed over distance then I'd say it was curved.  I think :)

DoctorBeaver

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What is the driving force behind photons?
« Reply #17 on: 25/11/2008 19:46:10 »
The only difference I can see between compression and warping is when the compression is linear across a region.  If the degree of compression changed over distance then I'd say it was curved.  I think :)

I'm not sure about that. I don't know enough about it. Even Lisa Randall got confused by it and had to be corrected by a mathematician.

LeeE

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What is the driving force behind photons?
« Reply #18 on: 25/11/2008 19:57:28 »
Heh, I'm not sure either, but if you plotted the degree of distortion against distance from a gravity source you'd get a curve.  The problem seems to be that you can't fit the curve to any specific direction, except radially from the source, and it's like looking at the graph edge-on, so you only see the axis and not the curve.  Dunno for sure though.

labview1958

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What is the driving force behind photons?
« Reply #19 on: 26/11/2008 13:31:54 »
Maybe space is being "burned" by the em wave as energy is needed to move. Thus in order for light to move space is somehow converted to time.

labview1958

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What is the driving force behind photons?
« Reply #20 on: 27/11/2008 14:20:54 »
If we put gunpowder in a straight line and light it. The fire will move along the path of the laid gunpowder. Space could be "burned" to provide energy for the light to move through it. Possible?

Bikerman

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What is the driving force behind photons?
« Reply #21 on: 27/11/2008 14:54:44 »
Err...using the same logic would not any object moving through space 'burn' it? Why would photons be special?
You also seem to be assuming that time and space are absolute and inter-convertable, whereas relativity tells us that both are relative.
We can regard movement through space/time as a whole - the more you move through space, the less (relatively) you move through time (and vice-versa) with the total always being c...

Soul Surfer

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What is the driving force behind photons?
« Reply #22 on: 02/12/2008 19:11:48 »
To return to the original question. 

The question is a classical example of conventional terrestrial thinking where objects do not move unless you push them and stop moving if you stop.

It is important to remember one of the fundamental laws of the universe,  that is the law of the conservation of energy. 

A photon is energy and nothing else and as described above it always moves at the velocity of light.  Each photon also represents the smallest possible quantity of energy at that frequency.

It follows that a photon moves from the moment it is emitted until the moment it is absorbed and no additional energy could possibly be needed, gained or lost.

labview1958

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What is the driving force behind photons?
« Reply #23 on: 11/12/2008 14:16:05 »
A photon is mass/energy. Could it be a photon is mass/energy/space. Which means a photon energy converts to space and back again. This gives the impression is moving forward.

LeeE

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What is the driving force behind photons?
« Reply #24 on: 11/12/2008 14:33:55 »
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A photon is mass/energy

I'm not sure that's a good or helpful way to think of energy.

While photons and matter are both forms of energy it's not really correct to say that they are the same as each other.  It's a bit like saying that cider is the same as apple pie, when the fact is that neither of them are apples.

 

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