Posts tagged with string theory

Mirror symmetry is an example of a duality, which occurs when two seemingly different systems are isomorphic in a non-trivial way. The non-triviality of mirror symmetry involves quantum corrections. It’s like the Fourier transform, where “local” in one domain translates to “global”—something requiring information from over the whole space—in the other domain.

a Fourier spike

Under a local/global isomorphism, complicated quantities get mapped to simple ones in the dual domain. For this reason the discovery of duality symmetries has revolutionized our understanding of quantum theories and string theory.


summer school on mirror symmetry (liberally edited)


Thinking about local-global dualities gave me another idea about my model-sketch of knowledge, ignorance & expectation.

  • Under physical limitations, at a fixed energy level, Fourier duality causes a complementary tradeoff between frequency and time domains—not both can be specific. Same with position & momentum, again at a fixed energy level.
  • Under human limitations, at a fixed commitment of effort|time|concentration, you can either dive deep into a few areas of knowledge|skill, or swim broadly over many areas of knowledge|skill.

If I could come up with a specific implementation of that duality it would impose a boundary constraint on that model-sketch. Which would be great as optimal time|effort|concentration|energy could be computed from other parts of decision theory.

Apparently the “extra” dimensions of string theory are only supposed to be a few millimetres thick.

If that’s the case, could you dodge a bullet by moving a millimetre in the 10th dimension?

I guess it would depend on how wide the bullet and your liver are in the 10th dimension. Could lead to an interesting superpower: move in hidden dimensions.

  • The hero wouldn’t be invulnerable but would be less vulnerable. Still get an exit wound but maybe she’d only be grazed through the interior rather than completely ripped to shreds.
  • Still worth dodging/blocking a fist in the normal-sized 3 dimensions, but even a “direct” uppercut or body blow could become more of a “glancing blow” if she dodged in the thin directions. (NB: If ∃ 7 extra thin dimensions, each 1mm wide, and she dodged at once to “the other side” of all 7 at once—assuming, as well, that we’re “all the way to one side” of each of the extra dimensions—then she’d have made a total distance of √7mm between her and us.)
  • Joint locks—could she put someone in a joint lock they couldn’t get out of? Couldn’t she also get out of joint locks that no-one else could?
  • Couldn’t become invisible but become less visible.
  • Couldn’t pass through walls but could reach into crevices easier.
  • Could swim faster (twist her torso in the 10th dimension so the hands & feet still pull water, but less resistance on the mass of the body).

Am I thinking about this right?

What is the world made of?There are twelve basic building blocks.

Six of these are quarks—- they go by the interesting names of up, down, charm, strange, bottom and top. (A proton, for instance, is made of two up quarks and one down quark.) The other six are leptons—- these include the electron and its two heavier siblings, the muon and the tauon, as well as three neutrinos.

There are four fundamental forces in the universe: gravity, electromagnetism, and the weak and strong nuclear forces. Each of these is produced by fundamental particles that act as carriers of the force…: …photon…graviton…eight…gluons…three…W+, … W- , … Z.

The behavior of all of these particles and forces is described with impeccable precision by the Standard Model, with one notable exception: gravity.



Being a theoretical physicist is like being up in a balloon. The balloon is held aloft by hot air. And the person in the balloon enjoys looking down on other people.