Transcript The Big Bang

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 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
Beam of neutrinos at CERN
Detector under Gran Sasso
Distance of 732 km
Time of flight 2.43 ms
Highly respected group
Result: early by 60 nanoseconds
0.003% faster than light in vacuum!
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
Three different types
Neutrino oscillation
• Gran Sasso experiment
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/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
Time dilation: muons
Muons created in upper atmosphere
v = 3 x 108 m/s
t = 2.2 x 10-6 s (lifetime)
d = 660m
Many muons detected at ground level
d = 10 km ?
Moving clocks run slow
Vampire muon
Relativity ‘skepticism’
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Extraordinary concept
Counter-intuitive
Only observable at tremendous speeds
Only observable for subatomic particles
Speed of light plays role of infinity
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Simple maths
Time and distance calculations
Personalization
Confusion of discovery and justification
Compare: evolution, climate science
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
• Revolution
• Cosmological implications
Matter warps space and time
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
• 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?)
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
If so
• Paradigm shift
• Slow, gradual process (DJ)
• Consensus process
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
Science journalism: news driven
Climate ‘skepticism’ is not scientific
Bjorn Lomborg
Summary
Extraordinary result
Indirect measurement
Contradicts theory
Special and general relativity
Contradicts experiment
Particle experiments
Astronomy experiments
Extraordinary evidence? X
But what if.... ?
What if result stands?
Extra dimensions
Shortcut?
Doesn’t violate relativity
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Unified field theory
7 dimensions curled up?
High energy
Lightest particles
Doesn’t contradict previous results
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First evidence of string theory ?
Further reading: ANTIMATTER
H