A Skeptic’s Guide to String Theory†

George Musser – 1 November 2008

† and not just string theory

1. THE PROBLEM OF UNIFICATION

The Tree of

Physics

Mercury Nov/Dec 97

2. THE ZOOM BUTTON

Powers of 10

© 1995-2008 by Michael W. Davidson and The Florida State University. Used by permission. http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/

Energy and Size in Quantum TheoryPositionMomentum

Energy and Size in Quantum Theory

Energy and Size in General Relativity

Threshold for Black Hole Formation

6 Kilometers 1 Solar Mass

1 Centimeter 1 Earth Mass

0.1 Millimeter 1 Moon Mass

Energy and Size in General Relativity

Energy and Size in Both Theories

Planck scale

The Fine Filigree of Spacetime

American Scientist Nov/Dec 91

3. IS QUANTUM GRAVITY SCIENCE?

Energy and Size in Both Theories

Planck scale

LHC

Cosmic raysAccelerator limit Known universeHuman

The Skeptic’s Dilemma

• If quantum gravity can’t be tested, is it really science?

• But if it’s not science, do we have to give up the pursuit of deeper explanation?

Moiré pattern

Photoelectric Effect

Photoelectric Effect

http://www.semiconductor-sanyo.com/images/amorton/feature/wavelength.gif

Science 299:1171 (2003)

Just because a theory isn’t (yet) falsifiable doesn’t mean it’s not scientific.

4. WHAT IT MEANS FOR SKEPTICS

• Use the unity of nature as a criterion for evaluating claims (but carefully).

• Never ascribe to design what you can ascribe to luck.

The Tree of

Physics

Mercury Nov/Dec 97

For a copy of the talk, visit www.strings.musser.com

BACKUP SLIDES

Moiré pattern

Particle Accelerators 101

www.atlas.ch/multimedia/animation_lhc_event.html; CERN-EX-0401001

www.ippp.dur.ac.uk/~georg/lhcilc/cern0702/lhclco_tricomi.pdf; iguanacms.web.cern.ch/iguanacms/gallery-page4.html

Creation of Gluinos

RAW MATERIAL

The Tree of

Physics

Mercury Nov/Dec 97

The Tree of PhysicsSi

mpl

er