From the Energizer Bunny, of course. That's why photons keep going and going and going. Energy and matter can't be destroyed. You can change one into the other but can't destroy one alone.

Nuclear fusion is my guess but don't tell anybody I said so. I don't want to appear dumb. Mr Q

Anyone, please jump in and correct me if I'm wrong, but I'm going to give this my best shot... 

The funny thing about photons is that they have zero mass.  So, therefore, they need no energy to accelerate, if you think about it in a classical physics kind of way.

Indeed in Newtonian physics, F = ma, states that given a force F, an object will accelerate at a rate directly proportional to that Force and inversely proportional to its mass.  If it has zero mass, you need no force.  However, it is probably improper to apply a Newtonian concept in Quantum physics.

Also, according to Newtonian physics, once an object is moving, it requires no more Force to keep it moving.

In a quantum sense, photons exhibit wave-like and particle-like properties.  If you consider the wave-like properties, a photon is propagated through alternating electric and magnetic (electromagnetic) fields.  Because an electric field will create a magnetic field at right angles and vice versa, the waves will continue to propagate through any medium, even a vacuum.

It's something like this:

One wave is the electric field and one is the magnetic field.  As the electric field maximizes, the magnetic field is at 90-degrees.  In this way, they can propagate without requiring energy, however, the magnitude of the wave diminishes as light spreads out.

I hope this helps.

-StarNerd

StarNerd:

Anyone, please jump in and correct me if I'm wrong, but I'm going to give this my best shot... 

all mater gives off radiation unless it is at absolute zero.  the background radiation from the big bang has not yet had enough time to cool down that low, so all matter radiates energy. 

at this point i should say that i mean 'normal' matter.  not anything mysterious like dark matter.

the energy that the radiated photons carry is proportional to the energy level of the matter that did the radiating. a low energy body may give off microwave or infrared photons.  something more energetic may give off ultraviolet or x-ray photons. 

a photon/light wave travels at the speed of light no matter its energy.  if the energy is more or less, the frequency (color) will be more or less.

StarNerd:

In this way, they can propagate without requiring energy, however, the magnitude of the wave diminishes as light spreads out.

the magnitude decreases in accordance with the inverse square law which states that the strength is inversely proportional to the square of the distance from the source.  so every time you double the distance the light has traveled, its magnitude is only one-fourth what it was. 

StarNerd:

The funny thing about photons is that they have zero mass.  So, therefore, they need no energy to accelerate, if you think about it in a classical physics kind of way.

Photons have zero 'at rest' mass.  Einstinian physics shows that as an object increases in speed, it's mass also increases.  if photons were truly massless a black hole would probably be a very bright object.

there's a whole lot more to this i'm sure...

That’s a good question for a traditional scientist which I am not. For me a photon represents an excited unit of the mind-energy aether or electromagnetism which is in all and through all. Photons are illusory and only appear to travel.

The energy of a photon depends on the process that took place to create it originally. Go back far enough in time and this would be... the big bang?

Photons are created in atomic nuclear interactions, such as brehmstralung when an electron decelerates. There are other processes, like compton scattering and chemical processes that creat photons. Generally the incident particle transfers its energy to the photon during these interactions. More energetic particles produce more energetic photons, although their velocity is always the speed of light. The energy is expressed as the frequency of the waves, not their velocity. Strong gravitational fields could slow them down.

It might be possible that in the space around black holes, near the event horizon, theres a region where photons are stationary. But I'm not sure about that, its just a thought.