Neutrinos at the Speed of Light: Challenging Einstein's Theories

1. Faster than the speed of light Was Einstein wrong? The Big Bang, the LHC and the God Particle Cormac O’Raifeartaigh (WIT) Cormac O’Raifeartaigh (WIT)

2. Overview I The OPERA experiment What, why, how II Relativity (special) Theory and experiment III Relativity (general) Theory and experiment IV Skepticism in science Coda: a mundane explanation

3. Beam of neutrinos at CERN Detector under Gran Sasso Distance of 732 km Time of flight 2.43 ms The OPERA experiment 0.003% faster than light ! Result: early by 60 nanoseconds

4. Neutrinos • Suggested by Pauli (1930) • Conservation of energy • Particle of zero charge, low mass • Weak interaction Skepticism Detected in 1956

5. Neutrino puzzles • Tiny mass (non-zero?) • Created in nuclear reactions • The solar neutrino paradox Three different types Neutrino oscillation OPERA experiment

6. Standard Model neutrino= lighter cousin of electron

7. The OPERA experiment

8. OPERA: The numbers • Measurement of distance (GPS) 732 km +/- 20 cm • Time of flight(GPS) 2.43006 ms +/- 10 ns • Velocity = distance/time Δv/v = 2.5 x 10-5 (25 ppm) Note: proton pulse 10 μs long (10,000 ns) 60 ns early (18 m??)

9. Not direct comparison Light does not travel through mountain Accurate measurement of distance Relies on GPS Accurate measurement of time-of-flight Relies on GPS and statistics (pulses) Relatively short distance/time Need to direct beam at the moon OPERA: The snags Systematic error ?

10. II The theory of relativity (special) • Laws of physics identical for observers in uniform motion • Speed of light in vacuum a fundamental constant Implications for bodies at high speed Length contraction Time dilation Mass increase E = mc2

11. Evidence for relativity • Early experiments Kaufmann, Bucherer • Particle accelerators Length contraction Time dilation Mass increase • Modern particle accelerators Speed limit Particle creation E = mc2

12. CERN (Geneva) • energy increase • velocity increase? K.E = 1/2mv2 mass increases

13. Relativity ‘skepticism’ • Extraordinary concept • Counter-intuitive • Only observable at tremendous speeds • Only observable for subatomic particles Speed of light plays role of infinity • Simple maths • Time and distance calculations • Personalization • Confusion of discovery and justification Dr Al Kelly ‘Einstein wrong’

14. III The general theory of relativity General Relativity (1915) • Laws of physics identical for all observers • Speed of light in vacuum a universal constant • Principle of equivalence Gravity = curvature of space and time • New view of gravity • Cosmological implications Matter warps space and time

15. General relativity (evidence) • Bending of starlight by sun • Eddington experiment • Time dilation by gravity • Pound experiment • Expanding universe • Hubble’s law • Geodesic effect • Everett experiment Breakdown at quantum scales

16. Skepticism from astronomy • Supernova • Huge implosion of massive star • Light released • Neutrinos released • Supernova 1987a • Neutrinos detected • Light detected • Time difference of 5 min Not 5 years !

17. Many years for new result to be accepted Must be reproducible Must fit known data IV Skepticism in science If so Thomas Kuhn • Paradigm shift • Slow, gradual process (DJ) • Consensus process Compare: accelerating universe

18. Scientific skepticism misunderstood Attributed to conservatism Role of evidence misunderstood ‘Balanced’ debate unweighted Skepticism in the media Bjorn Lomborg Science journalism: news driven

19. Extraordinary result Indirect measurement Contradicts theory Special and general relativity Contradicts experiment Particle experiments Astronomy experiments Extraordinary evidence? X Summary Explanation ?

20. The verdict • Reproducible? • Many checks carried out • Technical flaw discovered Cable to external GPS clock Accounts for time discrepancy • A second flaw • Internal clock Unreliable result Re-runs possible but not beneficial We told you so

21. Lessons to be learnt Unexpected result? Check, check, check Emphasis on simple errors 2. Do not publish If in conflict with theory and experiment 3. Do not underestimate the media ‘Einstein wrong’ is a huge story Further reading: ANTIMATTER

22. Relativity and GPS • Signal from satellite compare time received to transmitted synchronized clocks • Convert time to distance x speed of radiowaves • Triangulation using 4 sources • accurate to within 5 metres Assumes constancy of speed of light

23. GPS: a relativistic correction Synchronization of satellite/earth clocks • Motion of satellite (SR) Clocks slow by 7 μs/day • Reduced gravity field (GR) Clocks fast by 45 μs/day Satellite clocks fast by 38 μs/ day Well-known correction to GPS OPERA - new correction? (18m?)

24. What if result stands? • Extra dimensions Shortcut? Doesn’t violate relativity • Unified field theory 7 dimensions curled up? • High energy Lightest particles Doesn’t contradict previous results Further reading: ANTIMATTER First evidence of string theory ?

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