Einstein: Do We Really Understand What He Did 100 Years Ago

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• Einstein Do We Really Understand What He Did 100
  Years Ago?

Giorgio Margaritondo Vice-president for Academic
Affairs EPFL
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March the photon

• 2005
• 100th anniversary of Einsteins 1905 Magic Year
• Celebrations of planetary proportions
• An unmatched celebrity

June Relativity

• The magic 1905

September Emc2
May Brownian motion
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How famous is Albert Einstein today?
Example -- Einstein vs the world in
Google Albert Einstein 6970000
results Pamela Anderson 5320000
results Michael Schumacher 1740000
results Jacques Chirac 1670000
results Marie Curie 1580000
results Silvio Berlusconi 1040000
results Werner Heisenberg 291000
results Erwin Schroedinger 114000 results
G. Margaritondo 9990 results
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• but
• do we really understand (and teach)
• What were the results of Magic 1905?
• What do they mean?
• How were they obtained?
• How could Einstein find the courage to present
  them?
• Who was Albert Einstein?

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Reality or myth? Einstein derived relativity
from the Michelson-Morley experiment
In 1905, Einstein explained the data on the
photoelectric effect using photons.. Th
e paper on the motion discovered by the physicist
Brown is not as important as the other 1905
works Einsteins theory of photoelectrons was
immediately accepted but relativity remained
controversial.... Einstein failed his first
university admission test because of his
weakness in mathematics.. Einstein was an
absent-minded professor not interested in
practical questions......
PROBABLY FALSE FALSE TWICE FALSE FALSE FALSE
FALSE
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AN IMPORTANT ISSUE AFTER ELIMINATING
MISCONCEPTIONS, HISTORICAL DISTORTIONS AND
MISUNDERSTANDINGS, IS THE REAL EINSTEIN NOT AS
GREAT AS THE EINSTEIN MYTH?
ABSOLUTELY NOT! THE REAL EINSTEIN IS EVEN GREATER
THAN THE MYTHOLOGICAL ONE THE BOLDNESS OF WHAT
HE DID IN 1905 IS ASTONISHING PERHAPS
UNDERSTANDABLE IN OF A SEMI-GOD, IT IS INCREDIBLE
IN A HUMAN BEING
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the Brownian motion Ann. Phys. 17, 549
(1905) the least understood and almost
forgotten of Einsteins 1905 works
but a very important one arguably, the first
non-controversial proof of the existence of atoms
(with definite size) (later verified by
Jean-Baptiste Perrin)
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Historical misconception atoms, already proposed
by the Greek philosophers, became an accepted
scientific notion after Lavoisier
Reality until 1905, atoms were far from being
universally accepted by scientists. Rutherfords
experiment came only in 1906 and Thompsons
discovery of the electron was a blow for the atom
theory in classical physics, an electron cannot
be confined within a stable atom.
Boltzmanns statistical mechanics supported
atoms, but it was in deep trouble and almost
universally rejected (derivation apparently
flawed because of fluctuations, conflict with
time-reversible classical mechanics)
Einsteins 1905 work provides the way to settle
the issue
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The amazing history of the Brownian motion

• Brown, a botanist, discovers it in 1827
• In 1905, Einsteins uses atoms, molecules and the
  kinetic theory to predict, among other things,
  that the average Brown-particle displacement
  increases as the square root of time
• Jean Perrin, with experiments that started in
  1908, verifies the square root law the existence
  if atoms is finally established.

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The worst misconception the photoelectric effect
from a popular textbook Other scientists
before Einstein had discovered the
photoelectric effect. The scientists could not
explain the phenomenon as long as they assumed
that light only traveled in waves. To explain
the photoelectric effect Einstein used his theory
of quanta. from APS News, January 2005 In
March 1905 Einstein - still a lowly patent clerk
in Switzerland - published a paper explaining the
photoelectric effect.
Reality in 1905, the data did not yet exist!
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• Did Einstein in 1905
• Derive the existence of photons from the
  properties of the photoelectric effect?
• Inspired by Plancks foundation of quantum
  physics to conceive the photons and explain
  photoelectric data?
• NO -- In reality
• The results (in particular Lenards) on the
  photoelectric effects were not quantitatively
  adequate to derive the existence of photons
• Planck had not founded quantum physics and his
  work had no direct (but only indirect) impact on
  Einsteins derivation

What, then, did Einstein really do in 1905?
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• An intriguing and somewhat mysterious title A
  heuristic point of view on the production and
  transformation of light
• A work of supreme elegance Ann. Phys. 17, 132
  (1905) the calculation of the entropy change
  for the (adiabatic) expansion of a volume
  occupied by electromagnetic waves
• Using Wiens law, Einstein calculated that
• S - So (E/hn) k ln(V/Vo)
• This would be the same law as for an ideal gas if
  one could assume that
• (E/hn) the number of particles
• () heuristic A theory or approach which
  serves to promote discovery or learning by
  encouraging experimentation

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Einstein then boldly assumed that this was not a
mathematical coincidence, but a real things
photons were born!
and, with photons, modern physics, chemistry,
materials science, biology etc.
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• In particular, in the same article Ann. Phys.
  17, 132 (1905) Einstein used photons to predict
  (rather than to justify) the linear kinetic
  energy-frequency law for the photoelectric
  effect
• K hn - EB - ?
• This provided a way to verify the validity of the
  photon hypothesis and started one of the
  worst controversies in the history of science

• Between 1905 and 1915, the experimental
  verification of the linear law remained
  elusive
• In 1907, Ladenburg claimed that the speed and not
  the energy is linearly related to the frequency.
• The data of Hughes in 1912 were inconclusive.
• The data of Richardson and Compton in 1912 were
  also inconclusive.
• and the scientific world in general was against
  photons

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In 1915-16, Millikan Phys. Rev. 7, 355 (1916)
definitely proved the linear frequency law,
validating Einsteins photon theory
but in the same article Millikan continued to
deny the existence of photons!
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Before and even after Millikans work (and after
Comptons experiments), the existence of photons
remained controversial
That sometimes, as for instance in his
hypothesis of light quanta, he may have gone
overboard in his speculations should not be held
against him Plancks 1916 nomination of
Einstein to the Prussian Academy of
Sciences The hypothesis of light-quanta is not
able to throw light on the nature of radiation
Bohrs Nobel speech, 1922 But the conception
of localized light-quanta out of which Einstein
got his equation must still be regarded as far
from being established Millikans Nobel speech,
1923
..and, by the way, the term photon was invented
only in 1926!
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• Compared to the photon, relativity was less
  revolutionary

• The incompatibility of electromagnetism with
  Galileo relativity was evident
• The Lorentz transformation had been published by
  Lorentz in 1904. Lorentz had previously proposed
  the concept of local time and (together with but
  independently of Fitzgerald) the Lorentz
  contraction
• Einsteins role was similar to that in the case
  of photons -- he had the courage to believe the
  reality of exotic theoretical hypotheses

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• The Maxwell theory predicted the speed of light
  to be equal to (eomo)-1/2 regardless of the
  reference frame
• The only way to avoid interpreting this as speed
  of light constant is to assume that Maxwells
  equations are only valid in a special reference
  frame (the ether)
• This interpretation, however, clashes not only
  with experiments but also with the Galileian
  invariance of mechanics
• Einsteins main contribution was to take the
  formal result c (eomo)-1/2 at its face value

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• The second relativity article of 1905, however,
  does contain an element of genuine revolution mc2

• Note the consistent pattern
• Theory formally predicts a surprising and
  previously unknown property of nature
• Einstein considers the property as real and not
  just as a formal thing
• and then proposes a way to verify his bold
  assumption.

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A crucial question How could young Einstein find
the courage to propose revolutionary ideas such
as the photon hypothesis (and to some extent
relativity)?

• He was only 26 years old in 1905 and a fresh PhD
• He did not have an academic position a mistake
  would destroy his chances
• The photon hypothesis did indeed fly in the
  face of well-established facts in (classical)
  physics

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A plausible explanation The three works of 1905
are not independent of each other but all
connected together. Einstein did not produce
three independent results but a body of
interconnected results corroborating each other

• For example, the relativity work shows that the
  energy of a given quantity of light changes with
  the reference frame by the factor (1-b)/(1
  b)1/2
• This is the same law as the Doppler shift for
  frequency, thus the energy and ? are linearly
  related -- and this corroborates the photon
  hypothesis

In Einsteins words It is remarkable that the
energy and the frequency of a light complex vary
with the state of motion of the observer in
accordance with the same law
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Some other examples of links between the three
works of 1905

• The Brownian motion theory puts statistical
  mechanics on a solid ground. In turn, statistical
  mechanics is the foundation of the photon
  hypothesis
• The Brownian motion theory proves the existence
  of atoms but does not solve the problem of their
  stability. The coexistence of wave-like and
  particle-like properties - which is a consequence
  of the photon hypothesis - opens the door to the
  solution

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This coexistence, however, brings up a paradox
Einstein was the first to recognize that the
photon hypothesis leads to probabilistic physics
-- but strongly opposed it for the rest of his
life
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The historical deformations of Einstein as a
person are as important as those affecting his
work
a progressive transformation from a real human
being to a god-like icon
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that is becoming increasingly commercial and far
from the real Einstein
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Distortion is not unusual for historical figures
in science
Enrico Fermi, an oustanding scientist but a
dangerous person in the machine shop, became in
his wifes biography a great handyman
Marie Curie, a merry widow in Paris who did enjoy
life and love, was later transformed into a
saint-like icon (and almost no one is aware of
her top result)
Newton he wrote more about alchemy and to
advocate religious extremism than about science
Robert Millikan an icon in physics, but his
first publication of the electron charge work
without Fletcher, who did the experiment, raises
serious ethical questions
Galileo rightfully a legend, but probably the
tower of Pisa experiment never occurred it was
invented by his biographer Viviani
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Some of the historical misconceptions about
Einstein
Myth Einstein was so weak in math and science
that he failed the admission tests to the ETHZ
Reality He first tried the admission test at 16
before finishing high school. He passed in math
and science but failed in French (then considered
essential by the ETHZ!!!)
Reality He did change his ideas. Until the early
1930s, he advocated disarmament in spite of
Nazism, but changed mind in 1933 I would not,
in the present situation, refuse military
service. I would enter it in the belief that I
was helping European civilization
Myth Einstein was an illuminated philosopher,
consistent in his ideas
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Was Einstein the absent-minded professor pictured
by the media, not interested in applications? Not
at all!
1926 Einstein patented a gyrocompass and later
obtained for it royalties from a Dutch company
1935 Einstein patented a gyrocompass for
airplane navigation
1926-33 Work with Szilard on home refrigerators.
Patent on the Einstein-Szilard pump, later sold
for a substantial sum to the General Electric
company (Germany)
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My personal experience
And one of our main techniques is PHOTOEMISSION
Thus, we are directly linked to magic 1905 do
not tell me that Einstein was far from practical
things!
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A nice way to see relativity with your eyes
The answer is the Lorentz contraction due to the
speed of the electrons circulating in the machine
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How to fabricate x-rays with relativity
In reality, the magnet is fixed and the electrons
move (which is the same for relativity) the
wave forces the electrons to emit photons whose
wavelength is further decreased in the laboratory
frame by relativity (the Doppler effect)
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Einstein not a saint but a human being of blood
and flesh
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The possible role of Mileva Einstein in the 1905
relativity works is still controversial

• Some puzzling facts
• Mileva Maric was a physics student, the fifth
  woman student of the ETHZ. However, she did not
  graduate (she was unmarried and pregnant when she
  failed for the second and last time).
• Einstein wrote to her the following sentence
  How happy and proud I will be when the two of us
  together will have brought our work on the
  relative motion to a victorious conclusion!
• In the divorce agreement, Einstein gave to Mileva
  the entire amount of his Nobel prize.
• A contemporary witness, Abram Joffe, stated that
  the original relativity manuscript was signed
  Einstein-Marity (Marity is the Hungarian
  version of Maric). However, a Swiss husband can
  added his wifes maiden name to his family name.

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Is the real Einstein worse or better than the
Einstein icon?

• Actually, much better
• A young man, he showed incredible courage in
  proposing truly revolutionary ideas that could
  have jeopardized his future forever
• In politics, he was not afraid of changing ideas
  when he found to be wrong
• He was not afraid of going against discrimination
  and prejudice, from his personal experience of
  anti-semitism to the fight against Maccartism
• and his transformation into an icon was against
  his will

When reminded in 1927 that he revolutionized
science 20 years earlier, Einstein replied, "A
good joke should not be repeated too often."
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"Ladies and gentlemen, our age is proud of the
progress it has made in man's intellectual
development. The search and striving for truth
and knowledge is one of the highest of man's
qualities - though often, the pride is most
loudly voiced by those who strive the least. And
certainly we should take care not to make the
intellect our god it has, of course, powerful
muscles, but no personality. It cannot lead, it
can only serve and it is not fastidious in its
choice of a leader. This characteristic is
reflected in the qualities of its priests, the
intellectuals. The intellect has a sharp eye for
methods and tools, but is blind to ends and
values. So it is no wonder that this fatal
blindness is handed on from old to young and
today involves a whole generation."