I am a serious high school student with one year of physics class experience, so please point out if there are any flaws in my question or reasoning. Thanks!

Gamma ray radiation possesses a wavelength below 10 picometers ($10^{-11}\: \mathrm{m}$) and is capable of ionizing atoms. If a photon was endowed with sufficient energy ($~1.24 \times 10^{10}\: \mathrm{J}$) to yield a wavelength on the scale of a Planck length ($~1.62 \times 10^{-35}\: \mathrm{m}$), the theorized length of strings, would it be capable of producing interference or some other influence on strings, if they exist?

From what I have learned, string theory postulates that all matter and energy is composed of tiny vibrating strings that require 11 dimensions (please correct me if I am wrong). Would EM radiation with a wavelength on the scale of a string's length then be able to cause some sort of interference or influence on the string's properties or vibrational pattern?

Considering that an electron is so much larger than a string, such an experiment seems like trying to cause a ripple through a floating one inch piece of string by rapidly shifting an adjacent mountain one inch back and forth.

At such high energy levels, would an electron even be able to remain stable, or would it dissociate into its constituent particles? If so, would there be some amount of sufficient energy that would dissociate even those particles?

Here is the equation that I used to approximate the energy required to endow an electron with a wavelength of $~1.6 \times 10^{-35}\: \mathrm{m}$:

$$E=\frac{hc}{\lambda} = \frac{6.63 \times 10^{-34}\: \mathrm{Js} \cdot 3.00 \times 10^8\: \mathrm{m/s}}{1.62 \times 10^{-35}\: \mathrm{m}}= 1.23 \times 10^{10}\: \mathrm{J}$$

  • $\begingroup$ Such a high energy photon would potentially be able to put the string into a high energy vibration which could lead to the observation of very heavy particles not contained in the standard model. They can then decay to lighter particles etc. $\endgroup$
    – Dilaton
    May 26, 2013 at 22:24
  • $\begingroup$ Just wanted to point out, at this moment in time, unlike QED, relativity, ect, there is absolutely no evidence for string theory... $\endgroup$ Mar 23, 2015 at 18:16

1 Answer 1


The strings aren't physical objects that we can do things to. Remember, electromagnetic radiation is itself made of the same fundamental strings. As for the energy estimate, yes that's the range of energy one needs to be dealing with such distance scales, the Planck scale for all things physical. This is the energy for one quantum in some interaction. It is way, way beyond the technology of humans at this time.

There is, however, one approach to measuring indirect effects of strings, or other non-continuous space-time-matter, involving electromagnetic radiation. Astrophysicists are looking for arrival time difference for different wavelengths of radiation coming from very distance sources - quasars and whatever from the early universe. Just as there is dispersion in electron and phonon phenomena in solid state matter due to crystalline structure, any kind of Planck-scale structure in the "fabric of spacetime" should delay blue light relative to red, or UV relative to radio.

The trick, besides the challenging experimental work, is knowing if a distant cosmological source really emits the different wavelengths in one burst all at the same time.

Amusing side note... this isn't about string theory or Planck-scale phenomena, but about three decades ago when theorists were trying to unify all force except gravity. The energy scale was in the range of a few grams (iirc) (times $c^2$) for the bosons carrying the unified force, and they joked about "intermediate vector baseballs". With string theory, I haven't heard any joke names for the equivalent mass for that amount of energy, not yet...

  • 1
    $\begingroup$ These measurements of the discreteness of spacetime try to find evidence for quantum gravities like LQG and related approaches, they have nothing to do with ST where spacetime is not quantized. $\endgroup$
    – Dilaton
    May 26, 2013 at 22:18

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