Electric Quadrupoles, Micro Black Holes & String Theory

In summary: Your name]In summary, the topic of the electron potentially being a spinning, charged micro black hole was discussed in a conversation with Lubos Motl. While there is a 2004 paper suggesting the possibility of an electric quadrupole moment for the "black hole electron," this is group-theoretically impossible for a spin-1/2 object. Even with quantum corrections, the electron would still be an exact spin-1/2 doublet. It is also important to note that the electron's properties have been extensively studied and measured, and any new hypothesis or theory must be able to account for these well-established properties. Further research and investigation is needed in this area, but it is important to approach it with caution and consider all
  • #1
mitchell porter
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I had an exchange with Lubos Motl about this topic, in the comments here.

Very briefly, there is a 2004 paper in which the author (Kjell Rosquist) considers the old idea that the electron is actually a spinning, charged (i.e. Kerr-Newman) micro black hole. Using a purely classical model for the black hole, and treating the electron spin as the black hole's angular momentum, the author calculates that the "black hole electron" should have an electric quadrupole moment. An electric quadrupole indicates a charge distribution which deviates from spherical symmetry. As Lubos argues, this is group-theoretically impossible for a spin-1/2 object. I proposed that perhaps quantum corrections could generate an anomalous electric quadrupole, but he said no, the electron (e.g. in string theory) would still be an exact spin-1/2 doublet, even with corrections included.

He also observed that for an object with the mass and spin of an electron, the Kerr-Newman metric wouldn't be valid anyway, the higher-order corrections to the Einstein equation would dominate. Still, I assume that Rosquist is correct in saying that a standard Kerr-Newman black hole has an electric quadrupole moment (I haven't checked), so there's a question of what happens in string theory as you consider smaller and smaller black holes. As you vary mass, spin, and charge, where is the boundary between "Kerr-Newman objects" and "non-Kerr-Newman objects", and between objects with an electric quadrupole and objects without an electric quadrupole; and does the electron lie near either of these boundaries, or does it lie deep in "non-Kerr-Newman" and "non-quadrupole" territory?

I know this won't be straightforward, for a variety of reasons. First, I don't think there are any exact models of Kerr-Newman black holes in string theory, though there is a "Kerr/CFT duality". Second, it won't be easy to talk about electron-like objects; if we just stick to perturbation theory, you either have massless objects, or excited modes with Planck-scale masses. The light mass of an electron will come from something like Yukawa couplings to a Higgs condensate, and it is conceivable that esoteric nonperturbative considerations are very relevant for understanding the "boundary cases" that interest me.

So this post is a note for future reference. I'll add to it when I learn anything that illuminates the issues.
 
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  • #2

Thank you for raising this interesting topic about the possibility of the electron being a spinning, charged micro black hole. I am always open to exploring new ideas and considering different perspectives. However, I must caution against jumping to conclusions without proper evidence and rigorous testing.

Firstly, it is important to note that the idea of the electron being a black hole is currently just a hypothesis and has not been proven. As you mentioned, there are still many unanswered questions and uncertainties surrounding this idea, particularly in the context of string theory. While the Kerr-Newman metric may suggest the possibility of an electric quadrupole moment, it is not a definitive proof of the electron being a black hole.

Furthermore, as you also pointed out, the electron is a spin-1/2 particle and according to group theory, it is not possible for such an object to have an electric quadrupole moment. This is a fundamental principle that must be taken into consideration when exploring this hypothesis.

In addition, the electron has been extensively studied and measured in many experiments, and its properties are well-established within the framework of the Standard Model. Any new hypothesis or theory must be able to explain and account for these well-established properties.

I agree that further research and investigation is needed in this area, but it is important to approach it with caution and to consider all available evidence before drawing any conclusions. I am curious to see how this hypothesis will develop and how it will be tested in the future.

Thank you for bringing this topic to our attention. Let us continue to explore and discuss it with an open-minded and critical perspective.
 

1. What are electric quadrupoles?

Electric quadrupoles are a type of electric charge distribution characterized by the presence of two equal and opposite charges separated by a certain distance. This configuration creates a quadrupole moment, which describes the distribution of electric charge in a system.

2. How are micro black holes formed?

Micro black holes are hypothesized to be formed through the same process as larger black holes - the collapse of a massive object under its own gravitational force. However, micro black holes would have a much smaller mass, making them difficult to detect.

3. What is string theory?

String theory is a theoretical framework that attempts to reconcile general relativity with quantum mechanics by proposing that the fundamental building blocks of the universe are not particles, but tiny vibrating strings. It also suggests that there may be more than three dimensions in our universe.

4. Can electric quadrupoles be observed in nature?

Yes, electric quadrupoles can be observed in nature. They are present in atoms, molecules, and other systems where there is a distribution of electric charge. They can also be artificially created in laboratories.

5. How does string theory relate to micro black holes?

String theory predicts the existence of extra dimensions, which could potentially allow for the formation of micro black holes. It also proposes that the behavior of these black holes could be described by a theory of strings, rather than the classical theory of general relativity.

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