I discuss the difficulty of testing quantum theories of gravity empirically and the general question of verifiability in science. I also comment on how unified theories of physics can help skeptics evaluate novel claims.

1. A Skeptic’s Guide to String Theory†
George Musser – 1 November 2008
† and not just string theory

2. 1. THE PROBLEM OF UNIFICATION

3. The Tree
of
Physics
Mercury Nov/Dec 97

4. 2. THE ZOOM BUTTON

5. 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/

6. Energy and Size in Quantum Theory
PositionMomentum

7. Energy and Size in Quantum Theory

8. 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

9. Energy and Size in General Relativity

10. Energy and Size in Both Theories
Planck scale

11. The Fine Filigree of Spacetime
American Scientist Nov/Dec 91

12. 3. IS QUANTUM GRAVITY SCIENCE?

13. Energy and Size in Both Theories
Planck scale
LHC
Cosmic rays
Accelerator limit Known universeHuman

14. 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?

15. Moiré pattern

16. Photoelectric Effect

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

19. Science 299:1171 (2003)

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

21. 4. WHAT IT MEANS FOR SKEPTICS

22. • Use the unity of nature as a criterion for
evaluating claims (but carefully).
• Never ascribe to design what you can ascribe
to luck.

23. The Tree
of
Physics
Mercury Nov/Dec 97

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

25. BACKUP SLIDES

26. Moiré pattern

27. Particle
Accelerators
101
www.atlas.ch/multimedia/animation_lhc_event.html; CERN-EX-0401001

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

29. RAW MATERIAL

30. The Tree
of
Physics
Mercury Nov/Dec 97

31. The
Tree of
Physics
Simpler