Photon that "fits" into its schwarzschild radius

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SUMMARY

The discussion centers on the relationship between photon wavelengths and their corresponding Schwarzschild radii, specifically when half the wavelength (\lambda/2) equals the Schwarzschild radius (r_s). The calculations reveal that \lambda/2 = r_s = \sqrt{Gh/c^3} = \sqrt{2\pi}l_p, where l_p is the Planck length, and the mass of the photon is expressed as \sqrt{2\pi}\,m_p, with m_p being the Planck mass. The conversation explores the implications of these findings, questioning the significance of the simplicity of the formulas and the appropriateness of the Schwarzschild solution for massless photons. The discussion emphasizes the conceptual challenges in defining the size of photons and the conditions under which they might form black holes.

PREREQUISITES
  • Understanding of Schwarzschild radius and its implications in general relativity.
  • Familiarity with Planck units, specifically Planck length (l_p) and Planck mass (m_p).
  • Knowledge of photon properties, including energy-wavelength relationships.
  • Basic concepts of quantum mechanics and massless particles.
NEXT STEPS
  • Investigate the implications of high-energy photons in the context of black hole formation.
  • Explore the Schwarzschild solution and its applicability to massless particles.
  • Study the relationship between quantum mechanics and general relativity, particularly in extreme conditions.
  • Learn about the role of inertial reference frames in the behavior of photons and their wavelengths.
USEFUL FOR

Physicists, astrophysicists, and students of theoretical physics interested in the intersection of quantum mechanics and general relativity, particularly in understanding the behavior of photons in extreme gravitational fields.

birulami
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Photons with smaller and smaller wave lengths have a higher and higher energy and these engeries have an increasing Schwarzschild radius r_s. Consequently i can ask when half the wave length \lambda/2 is equal to r_s, such that one wave length fits into the sphere of the Schwarzschild radius.

I did the calculation and came out with \lambda/2 = r_s = \sqrt{Gh/c^3} =\sqrt{2\pi}l_p where l_p is the Planck length. Incidently the mass of this photon is \sqrt{2\pi}\,m_p with m_p being the Planck mass.

Now I wonder. Should I be at least a bit surprised about such extremely simple formulas or not. To put another way, is this as trivial as transforming ab=1 into a=1/b, or is there at least one physical statement needed between the Schwarzschild radius and this specific photon wave length? (Hmm, I hope someone can understand what I mean here. :confused:)
 
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Photons are massless and their size is not a very well defined concept - and it is definitely not equal to the wavelength. Furthermore your statement is frame dependent as I can find an inertial frame of reference where your photon has a wavelength in the radio wave band.
 
Before getting all wrapped up with photons and therefore quantum mechanics, why do you think the Swarzchild solution (boundary conditions being static and spherical) is an appropriate one for light?
 
Last edited:
Orodruin said:
Photons are massless and their size is not a very well defined concept - and it is definitely not equal to the wavelength. Furthermore your statement is frame dependent as I can find an inertial frame of reference where your photon has a wavelength in the radio wave band.

Since a photon has no inertial reference frame and is only a single object, it makes no sense to say that an extremely high energy photon is or is not a black hole. Making that classification is meaningless in the absence of some other object with which to interact. Now add an electron to the system.
It is certainly possible that the photon + electron system will have enough energy in a small enough space to form a black hole. This scenario would have meaningful and observable consequences since neither particle would continue to exist after the intersection.
 
Thanks for your answers, except I don't get it where you all are heading. I did not mention the term "black hole", I did not say that the photon has a certain size and I did not pronounce any appropriateness of the Schwarzschild solution for light. All i did was toy with some physical formulas out of curiosity and got an, at least for me, surprisingly simple result. My question is basically whether this is at least mildly surprising or completely trivial.
 

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