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)
Download ReportTranscript 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)
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) 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 The OPERA experiment Beam of neutrinos at CERN Detector under Gran Sasso Distance of 732 km Time of flight 2.43 ms 0.003% faster than light ! Result: early by 60 nanoseconds Neutrinos • Suggested by Pauli (1930) • Conservation of energy • Particle of zero charge, low mass • Weak interaction Skepticism Detected in 1956 Neutrino puzzles • Tiny mass (non-zero?) • Created in nuclear reactions • The solar neutrino paradox Three different types Neutrino oscillation OPERA experiment Standard Model neutrino = lighter cousin of electron The OPERA experiment 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??) OPERA: The snags 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 Systematic error ? 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 L(v ) L0 1 v 2 / c 2 Time dilation t (v ) t 0 / 1 v 2 / c 2 Mass increase m(v) m0 / 1 v 2 / c 2 E = mc2 Evidence for relativity Early experiments Kaufmann, Bucherer Particle accelerators Length contraction Time dilation Mass increase Modern particle accelerators Speed limit Particle creation E = mc2 CERN (Geneva) • energy increase • velocity increase? K.E = 1/2mv2 mass increases m(v) m0 / 1 v 2 / c 2 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’ 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 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 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 ! IV Skepticism in science Many years for new result to be accepted Must be reproducible Must fit known data If so • Paradigm shift • Slow, gradual process (DJ) • Consensus process Compare: accelerating universe Thomas Kuhn Skepticism in the media Scientific skepticism misunderstood Attributed to conservatism Role of evidence misunderstood ‘Balanced’ debate unweighted Bjorn Lomborg Science journalism: news driven Summary Extraordinary result Indirect measurement Contradicts theory Special and general relativity Contradicts experiment Particle experiments Astronomy experiments Extraordinary evidence? X Explanation ? 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 Lessons to be learnt 1. 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 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 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?) 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 • First evidence of string theory ? Further reading: ANTIMATTER <iframe width="560" height="315" src="http://www.youtube.com/embed/VBnkITI2nLM" frameborder="0" allowfullscreen></iframe>