JIM AL-KHALILI, HIS BOXER SHORTS AND THE SPEED OF LIGHT

http://www.guardian.co.uk/commentisf...?newsfeed=true
Jim Al-Khalili: "I'd love it if neutrinos really have exceeded the
speed of light. But I'm not eating my shorts just yet. (...) According
to our understanding of the laws of physics, nothing can exceed the
speed of light, an impressive billion kilometres an hour. And in my
experience, there is nothing that annoys people more about Einstein's
theory of relativity (for that is where this notion originates) than
its claim to this cosmic limit. Since Einstein's work in 1905,
thousands of experiments have only confirmed it – and indeed much of
the beautiful edifice of modern physics rests on it being correct. The
crucial point is not that light is so special but rather that this
speed limit is written into the fabric of space and time."

Jim Al-Khalili,

Neutrinos may or may not have exceeded the speed of light and yet I am
afraid you will have to eat your boxer shorts some day. Two
experiments - that of Michelson-Morley and that of Pound-Rebka - show
that the speed of light varies with v, the speed of the emitter
relative to the observer, in accordance with the equation c'=c+v given
by Newton's emission theory of light:

http://www.pitt.edu/~jdnorton/papers/companion.doc
John Norton: "These efforts were long misled by an exaggeration of the
importance of one experiment, the Michelson-Morley experiment, even
though Einstein later had trouble recalling if he even knew of the
experiment prior to his 1905 paper. This one experiment, in isolation,
has little force. Its null result happened to be fully compatible with
Newton's own emission theory of light. Located in the context of late
19th century electrodynamics when ether-based, wave theories of light
predominated, however, it presented a serious problem that exercised
the greatest theoretician of the day."

http://philsci-archive.pitt.edu/1743/2/Norton.pdf
John Norton: "In addition to his work as editor of the Einstein papers
in finding source material, Stachel assembled the many small clues
that reveal Einstein's serious consideration of an emission theory of
light; and he gave us the crucial insight that Einstein regarded the
Michelson-Morley experiment as evidence for the principle of
relativity, whereas later writers almost universally use it as support
for the light postulate of special relativity. Even today, this point
needs emphasis. The Michelson-Morley experiment is fully compatible
with an emission theory of light that CONTRADICTS THE LIGHT
POSTULATE."

http://groups.google.com/group/sci.p...abc7dbb30db6c2
John Norton: "THE MICHELSON-MORLEY EXPERIMENT IS FULLY COMPATIBLE WITH
AN EMISSION THEORY OF LIGHT THAT CONTRADICTS THE LIGHT POSTULATE."
Tom Roberts: "Sure. The fact that this one experiment is compatible
with other theories does not refute relativity in any way. The full
experimental record refutes most if not all emission theories, but not
relativity."
Pentcho Valev: "THE POUND-REBKA EXPERIMENT IS FULLY COMPATIBLE WITH AN
EMISSION THEORY OF LIGHT THAT CONTRADICTS THE LIGHT POSTULATE."
Tom Roberts: "Sure. But this experiment, too, does not refute
relativity. The full experimental record refutes most if not all
emission theories, but not relativity."

Of course, the epoch-making statement "But this experiment, too, does
not refute relativity" needs a lot of discussion that for the moment
is impossible in mainstream science. Still let me call your attention
to the concept of "protective belt" advanced by Imre Lakatos:

http://bertie.ccsu.edu/naturesci/PhilSci/Lakatos.html
"Lakatos distinguished between two parts of a scientific theory: its
"hard core" which contains its basic assumptions (or axioms, when set
out formally and explicitly), and its "protective belt", a surrounding
defensive set of "ad hoc" (produced for the occasion) hypotheses.
(...) In Lakatos' model, we have to explicitly take into account the
"ad hoc hypotheses" which serve as the protective belt. The protective
belt serves to deflect "refuting" propositions from the core
assumptions..."

The protective belt ("contracting lengths, local time, or Lorentz
transformations") referred to by Banesh Hoffmann:

http://www.amazon.com/Relativity-Its.../dp/0486406768
"Relativity and Its Roots" By Banesh Hoffmann: "Moreover, if light
consists of particles, as Einstein had suggested in his paper
submitted just thirteen weeks before this one, the second principle
seems absurd: A stone thrown from a speeding train can do far more
damage than one thrown from a train at rest; the speed of the particle
is not independent of the motion of the object emitting it. And if we
take light to consist of particles and assume that these particles
obey Newton's laws, they will conform to Newtonian relativity and thus
automatically account for the null result of the Michelson-Morley
experiment without recourse to contracting lengths, local time, or
Lorentz transformations. Yet, as we have seen, Einstein resisted the
temptation to account for the null result in terms of particles of
light and simple, familiar Newtonian ideas, and introduced as his
second postulate something that was more or less obvious when thought
of in terms of waves in an ether."

Pentcho Valev

http://personal.ph.surrey.ac.uk/~phs...tes11Nov08.pdf
Jim Al-Khalili (lecture notes): "Technically, M&M experiment showed
not that the speed of light is constant in all inertial frames but
rather that it was constant in all directions within the same frame.
It was not until 1932 when another famous experiment was carried out
(by Kennedy and Thorndike) that Einstein's second postulate was
properly proven: that speed of light is constant in all inertial
reference frames."

http://en.wikipedia.org/wiki/Kennedy...ike_experiment
Wikipedia: "While the Michelson-Morley experiment showed, that the
speed of light is independent of the orientation of the apparatus, the
Kennedy-Thorndike experiment showed that it is also independent of the
velocity of the apparatus in different inertial frames."

Jim Al-Khalili,

Obviously your lectures are based on Wikipedia but that is not very
good for your students. Are you sure that, while the Michelson-Morley
experiment confirms the variable speed of light c'=c+v predicted by
Newton's emission theory of light, the Kennedy-Thorndike experiment
refutes it?

http://personal.ph.surrey.ac.uk/~phs...tes11Nov08.pdf
Jim Al-Khalili: "Einstein's second postulate states that the speed of
light is the same in all inertial reference frames (or: speed of light
has the same value as measured by all observers no matter what their
relative velocity with respect to each other is)."

Do the following observers continue to measure the same speed of the
waves as they start moving towards the source?

http://a-levelphysicstutor.com/wav-doppler.php
"vO is the velocity of an observer moving towards the source. This
velocity is independent of the motion of the source. Hence, the
velocity of waves relative to the observer is c + vO. (...) The motion
of an observer does not alter the wavelength. The increase in
frequency is a result of the observer encountering more wavelengths in
a given time."

http://www.expo-db.be/ExposPrecedent...%20Doppler.pdf
"La variation de la fréquence observée lorsqu'il y a mouvement relatif
entre la source et l'observateur est appelée effet Doppler. (...) 6.
Source immobile - Observateur en mouvement: La distance entre les
crêtes, la longueur d'onde lambda ne change pas. Mais la vitesse des
crêtes par rapport à l'observateur change !"

http://www.phys.uconn.edu/~gibson/No...6_3/Sec6_3.htm
Professor George N. Gibson, University of Connecticut: "However, if
either the source or the observer is moving, things change. This is
called the Doppler effect. (...) To understand the moving observer,
imagine you are in a motorboat on the ocean. If you are not moving,
the boat will bob up and down with a certain frequency determined by
the ocean waves coming in. However, imagine that you are moving into
the waves fairly quickly. You will find that you bob up and down more
rapidly, because you hit the crests of the waves sooner than if you
were not moving. So, the frequency of the waves appears to be higher
to you than if you were not moving. Notice, THE WAVES THEMSELVES HAVE
NOT CHANGED, only your experience of them. Nevertheless, you would say
that the frequency has increased. Now imagine that you are returning
to shore, and so you are traveling in the same direction as the waves.
In this case, the waves may still overtake you, but AT A MUCH SLOWER
RATE - you will bob up and down more slowly. In fact, if you travel
with exactly the same speed as the waves, you will not bob up and down
at all. The same thing is true for sound waves, or ANY OTHER WAVES."

Pentcho Valev

Jim Al-Khalili irreversibly mutilates young minds:

http://www.facebook.com/note.php?not...22654397787009
Ask the Expert - answers from Prof Jim Al-Khalili
Question: "If the speed of light is constant, why is light affected by
the Doppler shift?"
Jim Al-Khalili: "In the Doppler shift, the speed of light (or sound)
is not what is affected; it is the wavelength that changes, and the
frequency. There is a formula for this: speed=wavelength x frequency.
So if a light source is travelling towards us, the waves of light
coming from it are getting squashed and so wavelength is smaller, but
they are arriving more rapidly, so frequency gets higher. The product
of smaller wavelength and higher frequency gives the same speed of
light always."

Jim Al-Khalili,

As the observer starts moving towards the source of SOUND, the speed
of sound waves relative to him increases while the wavelength remains
unchanged (the wavelength simply cannot depend on the movements of the
observer). The same happens in the case of LIGHT (see quotations
below).

Pentcho Valev wrote:

http://personal.ph.surrey.ac.uk/~phs...tes11Nov08.pdf
Jim Al-Khalili: "Einstein's second postulate states that the speed of
light is the same in all inertial reference frames (or: speed of light
has the same value as measured by all observers no matter what their
relative velocity with respect to each other is)."

Do the following observers continue to measure the same speed of the
waves as they start moving towards the source?

http://a-levelphysicstutor.com/wav-doppler.php
"vO is the velocity of an observer moving towards the source. This
velocity is independent of the motion of the source. Hence, the
velocity of waves relative to the observer is c + vO. (...) The motion
of an observer does not alter the wavelength. The increase in
frequency is a result of the observer encountering more wavelengths in
a given time."

http://www.expo-db.be/ExposPrecedent...%20Doppler.pdf
"La variation de la fréquence observée lorsqu'il y a mouvement relatif
entre la source et l'observateur est appelée effet Doppler. (...) 6.
Source immobile - Observateur en mouvement: La distance entre les
crêtes, la longueur d'onde lambda ne change pas. Mais la vitesse des
crêtes par rapport à l'observateur change !"

http://www.phys.uconn.edu/~gibson/No...6_3/Sec6_3.htm
Professor George N. Gibson, University of Connecticut: "However, if
either the source or the observer is moving, things change. This is
called the Doppler effect. (...) To understand the moving observer,
imagine you are in a motorboat on the ocean. If you are not moving,
the boat will bob up and down with a certain frequency determined by
the ocean waves coming in. However, imagine that you are moving into
the waves fairly quickly. You will find that you bob up and down more
rapidly, because you hit the crests of the waves sooner than if you
were not moving. So, the frequency of the waves appears to be higher
to you than if you were not moving. Notice, THE WAVES THEMSELVES HAVE
NOT CHANGED, only your experience of them. Nevertheless, you would say
that the frequency has increased. Now imagine that you are returning
to shore, and so you are traveling in the same direction as the waves.
In this case, the waves may still overtake you, but AT A MUCH SLOWER
RATE - you will bob up and down more slowly. In fact, if you travel
with exactly the same speed as the waves, you will not bob up and down
at all. The same thing is true for sound waves, or ANY OTHER WAVES."

Pentcho Valev

Jim Al-Khalili fiercely teaches Divine Albert's Divine Theory at the
University of Surrey:

http://personal.ph.surrey.ac.uk/~phs...TR-Lec3,4n.pdf
Jim Al-Khalili: "The speed of light has the same value (c) measured by
all observers no matter how fast they are moving relative to each
other. (e.g. the speed of light coming from the sun is the same
whether measured on Earth or on a rocket speeding away from the Solar
System at half the speed of light!)"

Jim Al-Khalili,

Is the wavelength of the light reaching the Earth equal to the
wavelength of the light reaching the rocket speeding away from the
Solar System at half the speed of light? If not, who or what has
caused the difference? That is, who or what stretches the wavelength
of the light reaching the rocket so that the speed of the light
measured on the rocket can gloriously be equal to the speed of the
light measured on Earth?

Do your students sing "Yes we all believe in relativity, relativity,
relativity", like Max Tegmark's students?

http://www.youtube.com/watch?v=5PkLLXhONvQ
We all believe in relativity, relativity, relativity.
Yes we all believe in relativity, relativity, relativity.
Einstein's postulates imply
That planes are shorter when they fly.
Their clocks are slowed by time dilation
And look warped from aberration.
We all believe in relativity, relativity, relativity.
Yes we all believe in relativity, relativity, relativity.

Pentcho Valev