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Parity Violation: The Biggest Scientific Blunder of the 20th Century?. Dr Mark Hadley. Is Nature Symmetrical?. We thought so until 1956 !!. A Major change in our view of space and time Round Earth Heliocentric view of Universe Special Relativity (time is not absolute)

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Parity Violation: The Biggest Scientific Blunder of the 20th Century?

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Parity violation the biggest scientific blunder of the 20th century l.jpg

Parity Violation: The Biggest Scientific Blunder of the 20th Century?

Dr Mark Hadley


Is nature symmetrical l.jpg

Is Nature Symmetrical?

We thought so until 1956 !!

  • A Major change in our view of space and time

  • Round Earth

  • Heliocentric view of Universe

  • Special Relativity (time is not absolute)

  • General relativity (spacetime is curved)

  • Big bang – Universe finite in space and time

  • Expanding Universe (time asymmetry)


Slide3 l.jpg

Plan

  • Parity violation – the conventional view

  • My interest

  • Review of Parity conservation

    • Mechanics

    • Electromagnetism

    • Weak Interactions

  • An alternative view

    • Parity is Conserved !!


Space inversion l.jpg

Space Inversion

Inversion = reflection + 180° rotation

Axial or Pseudo vector


Effect of parity momentum l.jpg

Before

After

Effect of Parity - momentum

The Parity Operator gives the transformation due an inversion of the spatial coordinates


Effect of parity spin l.jpg

Before

After

Effect of Parity - spin


Physical review october 1956 p254 258 l.jpg

Physical Review October 1956 p254-258

Parity violation in the weak interactions

Tsung Dao Lee

Chen Ning Yang


Start with a symmetrical state l.jpg

Look for an asymmetric outcome

Start with a symmetrical state

e-

θ

60Ni + e- +υe

60Co

I(θ)dθ = k (1 + αcosθ )sinθdθ


Experimentalists l.jpg

Experimentalists

Wu   Ambler   Hayward  Hoppes  Hudson

National Bureau of Standards USA 1956


Slide10 l.jpg

actual result

I(θ)dθ = k (1 –v/c cosθ )sinθdθ


Nobel prize winners 1957 l.jpg

Nobel prize winners 1957

Parity violation in the weak interactions

Tsung Dao Lee

Chen Ning Yang


But not quite so simple l.jpg

But not quite so simple…….

Is the initial state symmetrical?

“We see from this analysis that the logical path from the observed asymmetry to the inferred nonconservation of parity in β decay is considerably more complex than the popular presentations would indicate.”

L. E. Ballentine:


A gravitational explanation for quantum theory l.jpg

A gravitational explanation for quantum theory

  • Aims to explain

    • QM

    • Particle spectrum

    • Fundamental interactions

  • Predictions

    • No graviton (Gravity waves are just classical waves)

    • Spin-half

    • Parity is conserved


Parity is violated fact l.jpg

Parity is violated - FACT

The Nobel Prize Committee say so.

All the books say so.


Slide15 l.jpg

Doh !


Explanations using gr l.jpg

Explanations using GR

  • Boundary Conditions

  • Common source


Slide17 l.jpg

Doh!!

Doh !!


Where have they gone wrong l.jpg

Where have they gone wrong?

  • Exactly what has been observed?

  • Exactly what has been violated?

  • What, exactly, is the definition of Parity?


Parity in newtonian mechanics l.jpg

Parity in Newtonian Mechanics

Parity conserved

Before

After

F = ma

E = ½m v2

F = m(-a)

-F = m (-a)

-F = (-m)(-a)

F = (-m)(-a)

(± )E = ½(± m) v2


Parity in newtonian mechanics20 l.jpg

Parity in Newtonian Mechanics

P operator is chosen:

  • For simplicity

  • To conserve parity

  • Supported by:

    Special Relativity: (t-component of the energy momentum 4-vector)

    General Relativity:


Slide21 l.jpg

e-

e-

e-

e-

e-

Parity in electromagnetism

Start with a symmetrical state……

e-

Magnetic field pointing out


Parity in electromagnetism l.jpg

Parity in Electromagnetism

Parity conserved

Before

After

F = q(E + v x B)

Note:

-F = q(-E + -v x (-B))

-F = q(-E + -v x B)

-F = -q(E + -v x B)

-F = -q(E + -v x (-B))


Parity on magnetic poles l.jpg

Parity on magnetic poles


Slide24 l.jpg

e-

e-

e-

e-

Parity in electromagnetism

e-

Magnetic field pointing out


Slide25 l.jpg

e-

e-

e-

e-

e-

Magnetic field pointing in


Duality transforamtion l.jpg

Duality Transforamtion

  • The roles of E and B can be reversed by a duality transformation:


Parity in electromagnetism27 l.jpg

In this order

Parity in Electromagnetism

P operator is chosen:

  • To conserve parity

  • For simplicity

  • Supported by the covariant formulation:


Effect of parity l.jpg

Effect of Parity

The Parity Operator gives the transformation due an inversion of the spatial coordinates.

We do not have a free choice of P operator.

What are the transformations in beta decay?


Slide29 l.jpg

“We see from this analysis that the logical path from the observed asymmetry to the inferred nonconservation of parity in β decay is considerably more complex than the popular presentations would indicate.”

L. E. Ballentine:

The assumption that the Cobalt nucleous is symmetrical is not only non-trivial -

it may well be wrong !


What is the mirror image of a cobalt atom l.jpg

e-

e+

Anti 60Co

What is the mirror image of a Cobalt atom?

60Co

60Co

e-

(not to scale)


Parity l.jpg

Parity

  • Reverses

    • Momentum

    • Lepton number etc.

    • Charge

  • Unchanged

    • Spin

  • Is conserved


Conclusions l.jpg

Conclusions

  • Space Inversion is a symmetry of Nature

  • Parity is conserved

  • The conventional P operator is not conserved.


Just a change of convention l.jpg

Just a change of convention?

  • The conventional P operator may be combined with another transformation of degenerate multiplets. (eg particle anti-particle, neutrino flavours)

  • Impacts on unifying theories.

    “Not merely a matter of convention: on other particles P could have the usual effect.”

Weinberg


Parity violation l.jpg

Parity violation

How could they get it so wrong?


How could they get it so wrong l.jpg

How could they get it so wrong?

  • The Parity operation was defined before the experiments were done.

    • Particles were defined as eigenstates of Parity.

    • Simplicity of the operator took precendence over conservation - even though QFT required particles and antiparticles to be combined in the same equations.

  • There was no higher theory to appeal to.

Watch this space!


Parity is conserved l.jpg

Parity isConserved


Slide37 l.jpg

Eigenvectors of P, H,J3 with eigenvalues 0,M,σ

Parity

Lorentz Boost


Cp violation l.jpg

CP violation

  • Boundary conditions

    • Matter dominated Universe

  • T asymmetry (CPT theorem)

    • Expanding Universe

  • Parity = CP for some particles only!

  • More complicated effects of P on other degeneracies.


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