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Author Topic: What holds a photon together?  (Read 2303 times)

Offline thedoc

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What holds a photon together?
« on: 01/10/2015 15:50:01 »
Sheena asked the Naked Scientists:
   
If a photon is a 'packet' of energy, what is holding it together?

What do you think?
« Last Edit: 01/10/2015 15:50:01 by _system »


 

Offline PmbPhy

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Re: What holds a photon together?
« Reply #1 on: 01/10/2015 20:00:53 »
Quote from: Sheena
   
If a photon is a 'packet' of energy, what is holding it together?
The photon is a point particle. Like all point particles it needs nothing to hold it together and as such there is nothing holding it together. Perhaps if you could tell me why you think it needs to be held together I can help you address that thought.
 

Offline puppypower

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Re: What holds a photon together?
« Reply #2 on: 01/10/2015 20:31:05 »
A photon moves at the speed of light which is the same in all references. A photon also has wavelength and frequency which are inertial properties which can be different in all references. It has two mutually exclusive properties, all in one particle.

As a loose analogy, a photon acts like a basketball player who is stopped and can pivot on one planted foot. The other foot can move in any direction as fast or slow as it wishes; depends on the action. What glues these two mutually exclusive references together?


 

Offline PmbPhy

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Re: What holds a photon together?
« Reply #3 on: 01/10/2015 21:20:14 »
Quote from: puppypower
A photon also has wavelength and frequency which are inertial properties which can be different in all references. It has two mutually exclusive properties, all in one particle.
Wavelength and frequency are not mutually exclusive properties whatsoever. Where did you get that idea from?
 

Offline evan_au

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Re: What holds a photon together?
« Reply #4 on: 01/10/2015 22:06:55 »
Quote
If a photon is a 'packet' of energy, what is holding it together?
A photon can be considered to propagate as an electromagnetic wave, with an electric field and a magnetic field.
Maxwell showed that if you created this combination of electric and magnetic fields, it would travel through a vacuum as a unit, the electric and magnetic fields supporting each other.

This theory immediately explained light, and later, the radio waves created by Hertz.

What Maxwell didn't know is that there is a certain minimum unit of energy for light (E=hν), which we now call a photon. But Maxwell's equations still work for multiples of this minimum energy.
 

Offline chiralSPO

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Re: What holds a photon together?
« Reply #5 on: 01/10/2015 22:21:45 »
Sheena asked the Naked Scientists:
   
If a photon is a 'packet' of energy, what is holding it together?

What do you think?

I actually hate the use of "packet" in this context, as it does seem to imply a container of some sort. Really, a photon is a "unit" or "article" or "item" or "piece" of energy. As far as I know, photons are indivisible, and don't have any smaller components...
 

Offline PmbPhy

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Re: What holds a photon together?
« Reply #6 on: 02/10/2015 00:52:22 »
Quote from: evan_au
A photon can be considered to propagate as an electromagnetic wave, with an electric field and a magnetic field.
That's quite wrong. Photons don't have either and electric or magnetic field.
 

Offline acsinuk

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Re: What holds a photon together?
« Reply #7 on: 02/10/2015 11:23:22 »
IMHO a photon is an energy vibration at right angles to a magnetised area. Nothing to do with charged particles
 

Offline Thebox

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Re: What holds a photon together?
« Reply #8 on: 02/10/2015 13:14:34 »
Quote from: evan_au
A photon can be considered to propagate as an electromagnetic wave, with an electric field and a magnetic field.
That's quite wrong. Photons don't have either and electric or magnetic field.


Because it remains  ''virtual'' until the flow becomes compressed creating radiation pressure and interaction by the activator?


 

Offline jeffreyH

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Re: What holds a photon together?
« Reply #9 on: 02/10/2015 13:28:07 »
Quote from: evan_au
A photon can be considered to propagate as an electromagnetic wave, with an electric field and a magnetic field.
That's quite wrong. Photons don't have either and electric or magnetic field.

Pete I am glad you said that. I was beginning to think that I was in a minority.
 

Offline Thebox

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Re: What holds a photon together?
« Reply #10 on: 02/10/2015 13:33:11 »


Pete I am glad you said that. I was beginning to think that I was in a minority.

I agree with you and Pete, Photons do not have net charge in space, they have no magnetic properties, the are essentially dormant in space although travelling at c?

In saying that though, I read somewhere about the polarisation of Photons? is this myth or pop science speculation?
 

Offline evan_au

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Re: What holds a photon together?
« Reply #11 on: 02/10/2015 13:35:37 »
Quote from: PmbPhy
Photons don't have either an electric or magnetic field.
Can you please clarify that?

Light and radio waves are both composed of photons, and both are often described as electromagnetic radiation.

Or should I have said something like "an oscillating electric field and a magnetic field"?

How would you phrase it?
 

Offline PmbPhy

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Re: What holds a photon together?
« Reply #12 on: 02/10/2015 14:43:59 »
Quote from: evan_au
Quote from: PmbPhy
Photons don't have either an electric or magnetic field.
Can you please clarify that?
This is something I know by talking to people who know quantum field theory. It's not something I've learned yet. To my understanding to date photons quantize the EM field. Both the electric field and the magnetic fields are composed of photons. As such if you were to assert that photons are composed of electric and magnetic fields then you'd have a circularity.

Quote from: evan_au
How would you phrase it?
Until I finish studying quantum field theory I won't even make an attempt. In such cases if it's something I need to know like in this case I contact one of my buddies who know QFT solid. I've asked this question in the past and I was told that photons don't have an electric or magnetic field. Although I did see a quantum mechanics text which said otherwise. Physics can be confusing sometimes. :(
 

Offline lightarrow

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Re: What holds a photon together?
« Reply #13 on: 02/10/2015 18:03:48 »
Quote from: PmbPhy
Photons don't have either an electric or magnetic field.
Can you please clarify that?

Light and radio waves are both composed of photons, and bothhttp://www.thenakedscientists.com/forum/index.php?topic=60390.msg468293;topicseen#new are often described as electromagnetic radiation.

Or should I have said something like "an oscillating electric field and a magnetic field"?

How would you phrase it?
To use a methaphor, a photon is not made of electric or magnetic field in the same way that a string's mode of vibration is not made of the string's material.

--
lightarrow
 

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Re: What holds a photon together?
« Reply #13 on: 02/10/2015 18:03:48 »

 

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