Nature of photons presented in high school text books

In summary: This means it is the particle that carries light and other forms of electromagnetic radiation.In summary, textbooks have often associated photons with visible light, but they also exist in other areas of the electromagnetic spectrum. The photon model is supported by experimental and theoretical physics. While there is a distinction between classical waves and the internal field of a photon, asking about the internal field is not a meaningful question. Photons do exist, and while weaker sources may take longer to detect, there is no limit to the number of photons that can exist in the universe.
  • #1
hl_world
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Why did textbooks (when I was in high school 5 1/2 years ago) always associate photons with the visible light part of the EM spectrum. Wouldn't the radio, x-ray, gamma, etc. areas of the spectrum exist as photons too?

What about the transverse waves; would it not form a helix shape instead of the classic wave pattern on a flat plane? The former seems more realistic to me.

Do photons REALLY exist? Think about it - a particle of which there would be a finite number of in the universe. A light source emits a certain number of photons per 3 dimensional degree. Eventually, wouldn't said photons diverge enough that would render the light source invisible to any telescope (because no photons are available to enter the lens). It makes me think that radiation energy exists as a longitudinal wave (like sound through matter medium) but with some other unseen, unfelt, unknown medium.

Your thoughts?
 
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  • #2
From what I recall, "light" has erroneously been equated to "visible light."

I believe that in the simplest environment, a local vacuum, light waves (free photons) are sinusoidal and unpolarized.

The photon model fits with the vast majority of experimental and theoretical physics, from quantum mechanics to general relativity, from electromagnetism to thermodynamics.
 
  • #3
I always thought "light" meant visible light. Ie, X-rays aren't light, they are x-rays. But all are forms of em radiation.
 
  • #4
"Light" is sometimes used for electromagnetic radiation just beyond visible light, i. e., "infrared light" or "ultraviolet light."
 
  • #5
i see what you mean by the point of no photons available to enter the telescope and what happens is light is not emitted by the start at any specific direction but photons are emitted at random directions every second or fraction of a second, and during this the photons emitted by the light reaches every possible region in the universe and since the number photons emitted is very large it looks like the star is emitting the photons in all directions, that is why sometimes the telescopes point at the same astronomical objects for seconds,minutes and sometimes hours.
 
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  • #6
hl_world said:
Why did textbooks (when I was in high school 5 1/2 years ago) always associate photons with the visible light part of the EM spectrum. Wouldn't the radio, x-ray, gamma, etc. areas of the spectrum exist as photons too?
Yes.
hl_world said:
What about the transverse waves; would it not form a helix shape instead of the classic wave pattern on a flat plane? The former seems more realistic to me.
You need to make a distinction between a classical wave (or the wavefunction of a photon if you like) and the internal field of the photon itself. You can get classical transverse waves and you can get classical helical waves (one just has a linear polarisation, while the other has a circular polarisation). Asking what the internal field of a photon however is like asking what the internal mass/charge distribution of an electron is - a question that, to me, doesn't make a great deal of sense.

hl_world said:
Do photons REALLY exist?
Yes.
hl_world said:
Think about it - a particle of which there would be a finite number of in the universe. A light source emits a certain number of photons per 3 dimensional degree. Eventually, wouldn't said photons diverge enough that would render the light source invisible to any telescope (because no photons are available to enter the lens). It makes me think that radiation energy exists as a longitudinal wave (like sound through matter medium) but with some other unseen, unfelt, unknown medium.

Your thoughts?
Probabilistically, the weaker a source the less photons per unit time will strike the detector. Thus the weaker a source, the longer we need to look to see a photon, which is a fairly well understood imaging principle. In practice our ability to detect a source is limited by the number of false positives (or dark counts) a photon counter tends to generate.

Claude.
 
  • #7
In physics, the photon is the elementary particle responsible for electromagnetic phenomena.It is the carrier of electromagnetic radiation .
 

What is a photon?

A photon is a fundamental particle of light that has no mass and travels at the speed of light. It carries energy and can behave as both a particle and a wave.

How are photons produced?

Photons can be produced in a variety of ways, including through the emission of electrons in atoms, the decay of radioactive materials, and the collision of high energy particles.

What is the nature of light?

Light is made up of photons, which are the smallest unit of light. These photons have both wave-like and particle-like properties, and they travel in a straight line until they interact with matter.

How do photons interact with matter?

When photons interact with matter, they can be absorbed, reflected, or transmitted. The specific interaction depends on the properties of the material and the wavelength of the photon.

What is the relationship between photons and energy?

Photons carry energy, and the energy of a photon is directly proportional to its frequency. This relationship is described by the equation E=hf, where E is energy, h is Planck's constant, and f is frequency.

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