V. Gates, Empty Kangaroo, M. Roachcock, and W.C. Gall
Frank's Physics Institute, Eigenstate University of New and Improved York


This is the Web version of the seminar given at the FPI on 4/1/2000, and lectures given at the 1998 Jeffrey Harvey Summer School of Dance.

*I can't remember what goes in this footnote, for reasons explained in the title.

"A stitch in time saves nine in space"

- - - - - - - - - - Old folk theorem


Lobotomy is the most recent area of research in Cheerio theory (cosmology, phenomenology, cohomology, etc.) to develop from string theory:
--- the study of the D-braneing of strings [1,2].

From the audience: a frequent question

A response

In this talk, we review lobotomy and the developments that led to it: In the following section, we outline the history of string theory. The next section briefly reviews the main features of compactification. Finally, we complete the process by D-braneing.

The Bullshevik Revolutions

In the First String Revolution, S-matrix theorists discovered that dual models were really strings, which had a Lagrangian and Feynman rules just like ordinary field theory. Their immediate reaction was to quit dual models and go back to phenomenology. The few who remained then discovered that these strings existed only in spacetime dimensions D=26 or 10, so they switched to QCD and did real field theory.

In the Second String Revolution*, a string theory was temporarily thought to have an anomaly. So, people who didn't care about strings when they thought it didn't have an anomaly started working on it when they realized it still didn't have one. This discovery focused attention on the D=10 theory. Not-so-stringy people proposed D=11 supergravity or supermembranes, but because they were found impossible to quantize these alternatives received little attention.

In the Third String Revolution**, it was discovered that D=10 superstrings required M theory [3], which is based on D=11 supergravity or superMembranes. Stringy people then decided to take a cue from QCD: Having long since run out of amplitudes they could calculate, they started looking at classical solutions to the field equations, which they hand-waved into nonperturbative results. This had about as much success as QCDers who claimed to derive confinement from instantons.

*This is also known as the "First Superstring Revolution", so as to subtly ignore the existence of the First String Revolution.

**Also known as the "Second Superstring Revolution" by the instigators of the First Superstring Revolution; see previous footnote. However, since the Third String Revolution, tendency has been to ignore fermions altogether, since the interesting part of the solution comes from the bosons, so supersymmetry is a moot point, except indirectly through restrictions necessary to obtain the Standard Model, which ironically is already considered to be supersymmetric. A better name might be the Brane Revolution, since most researchers in this area no longer remember what the first two revolutions were about.

This will be reduced

One hopeful result was that the 5 string theories of D=10 became 1 membrane theory in D=11. This led to the principle of the "running of the dimensions": The farther you go, the fewer directions you have to go in. This explains the experimental observation that all roads lead to Rome. Thus, at the Planck length there are 11 dimensions, at everyday distances there are just 4, but if you go far enough, there aren't any! Consequently, the Big Bang is a simple consequence of the fact that the farther you go back in time, the fewer dimensions there were.

Unfortunately, this led to even more types of compactifications to D=4, and thus less predictabilty. We were thus also led to "running of predictabilty": In 11 dimensions, you can predict things uniquely; in 10 dimensions, you can predict up to a factor 5 of uncertainty; but by the time you get to 4 dimensions you can predict any value you want for a result.

One advantage of compactification* as described by is the introduction of new distance scales: For example, a mysterious new form of Heisenberg's uncertainty principle is that the smaller a particle is, the bigger the accelerator you need to create it. Thus roughly

Δx Δy ≥ 10-13 cm x 105 cm = (10-4 cm)2

Hence, a new scale is expected at a distance of about a micron, which might potentially be explained by compactification. Unfortunately, the collapse of extra dimensions in string theory has never been proven.**

*OK, it's the only one, but who's counting?

**However, there are stronger indications that it is string theory itself that has collapsed.

If I only had a brane

The absence of a proof for, or unique choice of, compactification led to a search for alternatives: According to the Random-Sundial scenario [4], extra dimensions have not gone away, it's just that nobody visits them anymore. Phenomenologists have had a quantum field day with this proposal: The vibrational modes of the string, like the notes on their neighbor's electric guitar, have kept them awake at nights thinking of ways to make them unobservable. (This is unusual, since normally curves only give them fits.) Because of the invisibility of nearby branes, whose presence is felt only through their weight, now even obesity can be attributed to dark matter. (But this does not solve the problem of how one can be obese and stringy at the same time.)

Brane theory also allows the simple derivation of a number of interesting mathematical identities:

(1) According to the AdS/MFT [5] correspondence, the massive modes decouple by the Applesauce-Calzone theorem.

(2) There are two kinds of physics:

  1. laxatives
  2. cathartics
These lends relevance to the mathematical identity


(3) Clobber-You compactification from D=10 implies the Beatle identity

1 + 1 + 1 = 3

We haven't figured out what it has to do with physics yet, but the mathematical relation is so profound there must be some application.

Dark problems

  1. If dark matter fell in the forest, would anyone hear it?
  2. Is anything darker than a black hole made out of dark matter?
  3. What is the politically correct term for people made of dark matter?
  4. How many of those people does it take to screw in a dark bulb?

Appendix: Proof that physics gets more depressing

There are (at least) three fundamental reasons that physics research can only get worse as a function of time:
  1. The easier stuff gets done first, so research gets harder.
    Yesterday's Nobel Prize winning work is merely today's homework problem.
  2. The field is expanding, leading to increasing specialization.
    QED people no longer understand QCD, and vice versa, and neither is even aware of QAD, QBD, QDD, etc.
  3. The distance between theory and experiment is exponentially increasing.
    Faraday did theory and experiment; so did Fermi.* How many theorists today can build an SSC in their basements, and how many experimentalists can prove the superstring is nonperturbatively finite?

*Lament of the Quantum Meteorologist:
When photons play,
But just Faraday,
Then it will be
Good enough Fermi.


  1. W. Siegel, Strings with dimension-dependent intercept, Nucl. Phys. B109 (1976) 244.
  2. V. Gates, Empty Kangaroo, M. Roachcock, and W. C. Gall, The Super G-String, in Unified String Theories, eds. M. Green and D. Gross, Proc. of Santa Barbara Workshop, Jul. 29 - Aug. 16 (World Scientific, Singapore, 1986) 729-737, section 4.
  3. The M(atrix), Warner Bros., 1999.
  4. Lisa Raman and Randall Humdrum, Where have all the dimensions gone?, JHETP Lett.1 (2000) 1999.
  5. G. Chalmers and K. Schalmers, Superpartners in high-energy group theory, Phys. Rev. D137 (2000) 838118714751847518475.
  6. George Mikrasov, The Windows pane is mainly a D-brane, I think I've got the preprint here somewhere.
  7. W.C. Gall, D-banes and the AdS epidemic, YITP preprint 00-xx.