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Selected developments in Physics during the last few centuries E. Matsinos

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Presentation on theme: "Selected developments in Physics during the last few centuries E. Matsinos"— Presentation transcript:

1 Selected developments in Physics during the last few centuries E. Matsinos

2 On how progress is made 27/6/20132Is this the end of Physics?

3 On how progress is made Complacency 27/6/20133Is this the end of Physics?

4 On how progress is made 27/6/20134Is this the end of Physics?

5 On how progress is made Dissension 27/6/20135Is this the end of Physics?

6 On how progress is made 27/6/2013Is this the end of Physics?6 Maximisation of activity (mainly by theorists)

7 On how progress is made 27/6/20137Is this the end of Physics? Nothing seems to make senseCreativity phase

8 On how progress is made Complacency 27/6/20138Is this the end of Physics?

9 The scientific method “Principles and procedures for the systematic pursuit of knowledge involving: – the recognition and formulation of a problem, – the collection of data through observation and experiment, and – the formulation and testing of hypotheses” [Webster's dictionary] 27/6/2013Is this the end of Physics?9

10 From Mythology to Geometry 27/6/2013Is this the end of Physics?10 Eratosthenes of Cyrene (276 BC – ca. 195 BC) First measurement of the Earth radius First measurement of the Moon radius (eclipse) First measurement of the Earth-Moon distance

11 From Mythology to Geometry 27/6/2013Is this the end of Physics?11 Aristarchus of Samos (310 BC – ca. 230 BC) First measurement of the Earth-Sun distance (a factor of 20 off!) First measurement of the Sun radius

12 From Mythology to Geometry 27/6/2013Is this the end of Physics?12 Aristarchus of Samos (310 BC – ca. 230 BC) Heliocentric Cosmology Why was Aristarchus’ Heliocentric Cosmology not accepted? o If the Earth moved, there should be constant ‘wind’ and the ground should disappear under our feet o If the Sun were the centre of the universe, then all objects (on the Earth) should fall onto (move toward) it o Stellar parallax Friedrich Wilhelm Bessel, 1838; mas ( ) Today’s value: mas (→ ly)

13 From Mythology to Geometry Claudius Ptolemy (ca. 90 – 168) o Almagest: the only surviving comprehensive ancient treatise on astronomy o Tables to compute future (or past) positions of the Sun, Moon, and planets; also the rising and the setting of the stars 27/6/201313Is this the end of Physics? Geocentric Cosmology

14 Medieval Cosmology 27/6/201314Is this the end of Physics? Wycliffe Translation Psalm 93:1 for he [the Lord] made steadfast the world; that shall not be moved Psalm 96:10 and he [the Lord] hath amended the world, that shall not be moved Psalm 104:5 which hast founded the earth on his stableness; it shall not be bowed into the world of world 1 Chronicles 10:3 for he [the Lord] hath founded the world unmoveable Ecclesiastes 1:5 the sun riseth, and goeth down, and turneth again to his place; and there it riseth again

15 Starting the scientific revolution Nicolaus Copernicus (1473 – 1543) Heliocentric Cosmology removed the Earth from its privileged status of being the ‘centre of the universe’ 27/6/201315Is this the end of Physics? De revolutionibus orbium coelestium, 1543

16 Starting the scientific revolution 27/6/201316Is this the end of Physics? From Copernicus' Commentariolus (1514): 1.There is no one centre of all the celestial circles or spheres. 2.The centre of the Earth is not the centre of the universe, but only of gravity and of the lunar sphere. 3.All the spheres revolve about the Sun the distance from the Earth to the Sun is imperceptible in comparison with the height of the firmament. 5.Whatever motion appears in the firmament arises not from any motion of the firmament, but from the Earth's motion. The Earth... performs a complete rotation on its fixed poles in a daily motion, while the firmament and highest heaven abide unchanged. 6.What appear to us as motions of the Sun arise not from its motion but from the motion of the Earth... We revolve about the Sun like any other planet. 7.The apparent retrograde and direct motion of the planets arises not from their motion, but from the Earth's. The motion of the Earth alone, therefore, suffices to explain so many apparent inequalities in the heavens.

17 Observations 27/6/2013Is this the end of Physics?17 Haec immatura a me iam frustra leguntur oy (These are at present too young to be read) Cynthiae figuras aemulatur Mater Amorum (Cynthia's figures are imitated by the Mother of Love)

18 History Isaac Newton (1642 – 1727) Foundation of Classical Mechanics 27/6/201318Is this the end of Physics?

19 History 27/6/2013Is this the end of Physics?19 The nature of light – Newton (particle aspect) – Huygens (wave aspect) – Rømer (c is finite, Io’s eclipses, 1676) – Young’s experiment (1803) The classification of the elements – Lavoisier – Gay-Lussac – Mendeleyev Electromagnetism – Ørsted – Faraday

20 History 27/6/201320Is this the end of Physics? Differential form of Maxwell’s ‘microscopic’ equations Gauss’ law Gauss’ law for magnetism Faraday’s law Ampère’s law

21 History Classical Physics Gravitation (Newton) Electromagnetism (Maxwell) Galilean transformation Open questions/problems – Invariance of laws of Physics – Relativity principle – Introduction of aether – Structure of matter 27/6/2013Is this the end of Physics?21

22 History 27/6/201322Is this the end of Physics? The Michelson–Morley experiment (1887) Aimed at detecting the relative motion of matter relative to the luminiferous aether (aether wind) Negative result

23 History Albert Einstein (1879 – 1955) Special Theory of Relativity (1905) General Theory of Relativity (1915) Strong gravitational fields distort the space-time It did not take long for GR to be tested and verified – precession of Mercury’s perihelion, – deflection of light of remote galaxies, … 27/6/201323Is this the end of Physics?

24 History General Relativity generalises Special Relativity and Newton’s law of universal gravitation, providing a unified description of gravity as a geometric property of space-time 27/6/201324Is this the end of Physics?

25 History 27/6/201325Is this the end of Physics? Correction (arcsec/century)Cause ±0.69 Gravitational tugs of the other planets Oblateness of the Sun (quadrupole moment) ±0.69Total ‘theoretical’ ±0.65Observed Precession of the perihelion of Mercury’s orbit Recognised in 1859 as a problem in celestial mechanics by Urbain Le Verrier (re-analysis of the transits of Mercury over the Sun’s disk from 1697 to 1848); Le Verrier estimated an anomaly of 38 arcsec/century Correction (arcsec/century)Cause ±0.69 Gravitational tugs of the other planets Oblateness of the Sun (quadrupole moment) 42.98±0.04General Relativity ±0.69Total ‘theoretical’ ±0.65Observed

26 An ‘extreme case’ of precession Binary-star system: two neutron stars (M ~ 1.4M ☼ ) orbiting each other → precession of the periastron: yr -1 o T= hr o  = o a=1,950,100 km o Rate of decrease of orbital period: 76.5  s/yr o Rate of decrease of semi-major axis: 3.5 m/yr o Calculated lifetime: 300 Myr 27/6/201326Is this the end of Physics? PSR B (Hulse–Taylor binary pulsar)

27 History 27/6/201327Is this the end of Physics? Gravitational deflection of light arcsec

28 History 27/6/201328Is this the end of Physics? Gravitational deflection of light

29 History The ray-frenzy era Röntgen von Laue Bequerel Curie’s Rutherford 27/6/2013Is this the end of Physics?29 First Solvay Conference, 1911

30 History 27/6/2013Is this the end of Physics?30 ‘… as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you’ Plum-pudding model First ‘realistic’ model of the atom

31 History Quantum mechanics Planck Rutherford Bohr Pauli Heisenberg Schrödinger de Broglie Born Dirac 27/6/2013Is this the end of Physics?31 Fifth Solvay Conference, 1927

32 Fundamental forces and elementary particles (1 st half of 20 th century) 27/6/2013Is this the end of Physics?32 Gravitation ElectromagnetismQuantum Theory Electron (Thomson, 1897) Proton (Rutherford, 1919) Neutron (Chatwick, 1932) - Rutherford Antielectron (Anderson, 1932) - Dirac Muon (Anderson, 1936) Pion (Powell, 1947) - Yukawa One problem solved (electrons in stable orbits), another remained (stability of the nucleus)

33 Fundamental forces and elementary particles (2 nd half of 20 th century) 27/6/2013Is this the end of Physics?33 Birth of Quantum Electrodynamics (QED) Feynman, Schwinger, and Tomonaga (Maxwell’s equations + Quantum Theory + Special Theory of Relativity)

34 Fundamental forces and elementary particles (2 nd half of 20 th century) 27/6/2013Is this the end of Physics?34 Cockcroft-Walton Cyclotron (Lawrence) Synchrotron (McMillan) 1952: BNL, proton synchrotron, 3 GeV; Cosmotron

35 Fundamental forces and elementary particles (2 nd half of 20 th century) 27/6/2013Is this the end of Physics? : Berkeley, 6 GeV; Bevatron1957: Dubna, 10 GeV; Synchrophasotron 1957: CERN, 28 GeV; PS ring New particles were discovered with these accelerators Further discoveries Electron neutrino (Cowen and Reines, 1953) - Pauli Muon neutrino (Steinberger, Ledermann, and Schwartz, 1962)

36 Fundamental forces and elementary particles (2 nd half of 20 th century) 27/6/2013Is this the end of Physics?36

37 Fundamental forces and elementary particles (2 nd half of 20 th century) 27/6/2013Is this the end of Physics?37 Gell-Mann and Ne’eman arranged the existing hadrons in geometrical patterns Gell-Mann predicted the existence of a new particle in 1962, discovered one year later Friedman, Kendall, and Taylor showed that the proton has structure Gell-Mann and Zweig introduced the quarks as elementary blocks of matter Baryons consist of three quarks Mesons consist of a quark-antiquark pair Introduction of ‘colour’ Quantum Chromodynamics (QCD) is born Fritzsch, Gell-Mann, and Leutwyler (early 1970s) The six quarks (u, d, c, s, t, and b) are the building blocks of the hadrons and they interact by exchanging gluons

38 Fundamental forces and elementary particles (2 nd half of 20 th century) 27/6/2013Is this the end of Physics?38 GRQEDWeakQCD Do these states really exist? 11/

39 Fundamental forces and elementary particles (2 nd half of 20 th century) 27/6/2013Is this the end of Physics?39 GRQEDWeakQCD Electroweak Glashow, Weinberg, and Salam (Higgs, t’ Hooft) First evidence for W , W , Z  (UA1 and UA2, 1983) First evidence for gluons (three-jet events, PLUTO, 1978) Standard Model The Higgs boson was tentatively confirmed to exist on 14 March 2013 (ATLAS and CMS, 4 July 2012) ~ 125

40 Unification: problems There is no real unification between the Electroweak interaction and QCD; they simply co- exist within the Standard Model There is little logics in the grouping of the elementary blocks of matter Fermion-boson asymmetry The Standard Model contains 24 parameters which cannot be obtained from ‘principles’ GRAVITY AND QUANTUM THEORY ARE CONCEPTUALLY INCOMPATIBLE 27/6/2013Is this the end of Physics?40

41 Unification: why bother? Order and simplicity At the early times of the Universe, gravitation was equally important as the other forces Quantum fluctuations in the ‘primeval soup’ led to the creation of stars and galaxies 27/6/2013Is this the end of Physics?41

42 Unification 27/6/2013Is this the end of Physics?42 String Theory (1980s) All the particles (and all forms of energy) in the Universe may be identified as one-dimensional, tiny 'strings' Our Universe is functioning in ten (or eleven) dimensions! Five string theories have emerged and seem to be self-consistent! M-theory (Witten, 1994) ‘The true sign of intelligence is not knowledge, but imagination’ [Albert Einstein]

43 Future 'The most important fundamental laws and facts of physical science have all been discovered, and these are now so firmly established that the possibility of their ever being supplemented in consequence of new discoveries is exceedingly remote... Our future discoveries must be looked for in the sixth place of decimals.' Albert Michelson, University of Chicago, /6/2013Is this the end of Physics?43

44 Thank you! 27/6/2013Is this the end of Physics?44 E. Matsinos


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