The Big Bang, the LHC and the God Particle Cormac O’Raifeartaigh (WIT) Faster than the speed of...
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Transcript of The Big Bang, the LHC and the God Particle Cormac O’Raifeartaigh (WIT) Faster than the speed of...
The Big Bang, the LHC and the God Particle
Cormac O’Raifeartaigh (WIT)
Faster than the speed of light
Was Einstein wrong?
Cormac O’Raifeartaigh (WIT)
Overview
I The experiment
What, why, how
II Relativity (special)
Theory and experiment
III Relativity (general)
Theory and experiment
IV Skepticism in science Coda: what if..?
The OPERA experiment
Result: early by 60 nanoseconds
Beam of neutrinos at CERN
Detector under Gran Sasso
Distance of 732 km
Time of flight 2.43 ms
0.003% faster than light in vacuum!
Highly respected group
Neutrinos
• Suggested by Pauli (1930)
• Conservation of energy
• Zero charge, ‘zero’ mass
• Weak interaction
• Skepticism (non-physicists)
Detected in 1956
Neutrinos
• Tiny mass (non-zero?)
• Dark matter? • The solar neutrino paradox
• Gran Sasso experiment
Three different types Neutrino oscillation
Change of flavour
Standard Model
neutrino = lighter cousin of electron
The OPERA experiment
OPERA: the numbers
Measurement of distance (GPS)
732 km +/- 20 cm
• Time of flight +/- 10ns
2.43006 +/- 0.00001 ms
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 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/timeNeed 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
Length contraction
Time dilation
Mass increase
220 /1)( cvLvL
220 /1/)( cvtvt
220 /1/)( cvmvm
E = mc2
Implications for bodies at high speed
Early experiments Kaufmann, Bucherer
Particle accelerators Length contraction
Time dilation Mass increase
Modern particle accelerators Speed limit
Particle creation E = mc2
Evidence for relativity
CERN (Geneva)
• energy increase
• velocity increase?
K.E = 1/2mv2
mass increases
Time dilation: muons
v = 3 x 108 m/s
t = 2.2 x 10-6 s (lifetime)
d = 660m
Moving clocks run slow
Many muons detected at ground level d = 10 km ?
Muons created in upper atmosphere
Vampire muon
Relativity ‘skepticism’
• Extraordinary concept• Counter-intuitive • Only observable at tremendous speeds• Only observable for subatomic particles
• Simple maths• Time and distance calculations • Personalization• Confusion of discovery and justification
Compare: evolution, climate science
Speed of light plays role of infinity
Dr Al Kelly ‘Einstein wrong’
III The general theory of relativity
Gravity = curvature of space and time
• Laws of physics identical for all observers• Speed of light in vacuum a universal constant• Principle of equivalence
• New view of gravity• Revolution• Cosmological implications Matter warps space and time
General Relativity (1915)
General relativity (experiment)
Predictions• Bending of starlight by sun• Black holes• Expanding universe• Geodesic effect• Time dilation by gravity
Evidence• Eddington experiment• Astronomy • Cosmology (big bang)• Everett experiment • GPS
Breakdown at quantum scales
Relativity and GPS
• Signal from satellite
compare time received to transmitted
synchronized clocks
• Convert time to distance
x speed of radiowaves
Assumes constancy of speed of light
• Triangulation using 4 sources accurate to within 5 metres
GPS: a relativistic correction
• 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?)
Synchronization of satellite/earth clocks
Skepticism from astronomy
Supernova• Huge implosion of massive star• Neutrinos released• Light delayed
Supernova 1987a• Neutrinos detected• Ahead of light by 3 hours
Not by 5 years !
IV Skepticism in science
Many years for new result to be accepted
Must be reproducible
Must fit known experiments
• Paradigm shift• Slow, gradual process (DJ)• Consensus process
If so
Compare: accelerating universe
Thomas Kuhn
The OPERA viewpoint
‘Despite the large significance of the measurement reported here and the stability of the analysis, the potentially great impact of the result motivates the continuation of our studies in order to investigate possible still unknown systematic effects that could explain the observed anomaly. We deliberately do not attempt any theoretical or phenomenological interpretation of the results’ ‘Up to half of the members of the OPERA project are opposed to immediately publishing the result in a peer-reviewed journal. They do not believe any known mistakes are being hidden by other members of the group, but are worried about the significant impact to physics of the results.’ Physics World
Science in the media
Scientific skepticism misunderstood
Attributed to conservatism
Role of evidence misunderstood
‘Balanced’ debate unweighted
Climate ‘skepticism’ is not scientific
Science journalism: news driven Bjorn Lomborg
SummaryExtraordinary result Indirect measurement
Contradicts theorySpecial and general relativity
Contradicts experimentParticle experimentsAstronomy experiments
Extraordinary evidence? X
But what if.... ?
What if result stands?
First evidence of string theory ?
• Extra dimensionsShortcut?
Doesn’t violate relativity
• Unified field theory 7 dimensions curled up?
• High energy Lightest particlesDoesn’t contradict previous results
Further reading: ANTIMATTER
H