🚀 go-pugleaf

Einsteiniana: Divine Albert said the speed of light is variable and
this is perfectly valid and makes good physical sense but we now say
the speed of light is constant and that's it:

http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/speed_of_light.html
Steve Carlip: "Is c, the speed of light in vacuum, constant? At the
1983 Conference Generale des Poids et Mesures, the following SI
(Systeme International) definition of the metre was adopted: The metre
is the length of the path travelled by light in vacuum during a time
interval of 1/299 792 458 of a second. This defines the speed of light
in vacuum to be exactly 299,792,458 m/s. This provides a very short
answer to the question "Is c constant": Yes, c is constant by
definition! (...) Einstein went on to discover a more general theory
of relativity which explained gravity in terms of curved spacetime,
and he talked about the speed of light changing in this new theory. In
the 1920 book "Relativity: the special and general theory" he wrote:
"...according to the general theory of relativity, the law of the
constancy of the velocity of light in vacuo, which constitutes one of
the two fundamental assumptions in the special theory of relativity
[...] cannot claim any unlimited validity. A curvature of rays of
light can only take place when the velocity of propagation of light
varies with position." Since Einstein talks of velocity (a vector
quantity: speed with direction) rather than speed alone, it is not
clear that he meant the speed will change, but the reference to
special relativity suggests that he did mean so. This interpretation
is perfectly valid and makes good physical sense, but a more modern
interpretation is that the speed of light is constant in general
relativity."

Einsteiniana: An infinitely long body can safely be trapped inside an
infinitely short container; the infinitely long body remains trapped
inside the infinitely short container in an infinitely compressed
state:

http://math.ucr.edu/home/baez/physics/Relativity/SR/barn_pole.html
"These are the props. You own a barn, 40m long, with automatic doors
at either end, that can be opened and closed simultaneously by a
switch. You also have a pole, 80m long, which of course won't fit in
the barn. Now someone takes the pole and tries to run (at nearly the
speed of light) through the barn with the pole horizontal. Special
Relativity (SR) says that a moving object is contracted in the
direction of motion: this is called the Lorentz Contraction. So, if
the pole is set in motion lengthwise, then it will contract in the
reference frame of a stationary observer.....So, as the pole passes
through the barn, there is an instant when it is completely within the
barn. At that instant, you close both doors simultaneously, with your
switch. Of course, you open them again pretty quickly, but at least
momentarily you had the contracted pole shut up in your barn. The
runner emerges from the far door unscathed.....If the doors are kept
shut the rod will obviously smash into the barn door at one end. If
the door withstands this the leading end of the rod will come to rest
in the frame of reference of the stationary observer. There can be no
such thing as a rigid rod in relativity so the trailing end will not
stop immediately and the rod will be compressed beyond the amount it
was Lorentz contracted. If it does not explode under the strain and it
is sufficiently elastic it will come to rest and start to spring back
to its natural shape but since it is too big for the barn the other
end is now going to crash into the back door and the rod will be
trapped in a compressed state inside the barn."

Einsteiniana: An observer sees the bug squashed; the bug sees itself
alive and kicking. This does not refute Divine Albert's Divine Theory.
Rather, this gloriously demonstrates the unlimited deductive power of
Divine Albert's Divine Theory:

http://hyperphysics.phy-astr.gsu.edu/Hbase/Relativ/bugrivet.html
"The bug-rivet paradox is a variation on the twin paradox and is
similar to the pole-barn paradox.....The end of the rivet hits the
bottom of the hole before the head of the rivet hits the wall. So it
looks like the bug is squashed.....All this is nonsense from the bug's
point of view. The rivet head hits the wall when the rivet end is just
0.35 cm down in the hole! The rivet doesn't get close to the
bug....The paradox is not resolved."

Selected Einsteinians (e.g. John Norton) are entitled to reject the
important consequence of Einstein's 1905 false light postulate
establishing the passage of time as an illusion. All other believers
should, like Brian Greene, constantly procrusteanize their minds into
conformity with the consequence establishing the passsage of time as
an illusion:

http://rescomp.stanford.edu/~cheshire/EinsteinQuotes.html
Albert Einstein: "People like us, who believe in physics, know that
the distinction between past, present, and future is only a stubbornly
persistent illusion."

http://www.pitt.edu/~jdnorton/Goodies/passage/index.html
John Norton: "A common belief among philosophers of physics is that
the passage of time of ordinary experience is merely an illusion. The
idea is seductive since it explains away the awkward fact that our
best physical theories of space and time have yet to capture this
passage. I urge that we should resist the idea. We know what illusions
are like and how to detect them. Passage exhibits no sign of being an
illusion....Following from the work of Einstein, Minkowski and many
more, physics has given a wonderfully powerful conception of space and
time. Relativity theory, in its most perspicacious form, melds space
and time together to form a four-dimensional spacetime. The study of
motion in space and and all other processes that unfold in them merely
reduce to the study of an odd sort of geometry that prevails in
spacetime. In many ways, time turns out to be just like space. In this
spacetime geometry, there are differences between space and time. But
a difference that somehow captures the passage of time is not to be
found. There is no passage of time. There are temporal orderings. We
can identify earlier and later stages of temporal processes and
everything in between. What we cannot find is a passing of those
stages that recapitulates the presentation of the successive moments
to our consciousness, all centered on the one preferred moment of
"now." At first, that seems like an extraordinary lacuna. It is, it
would seem, a failure of our best physical theories of time to capture
one of time's most important properties. However the longer one works
with the physics, the less worrisome it becomes....I was, I confess, a
happy and contented believer that passage is an illusion. It did
bother me a little that we seemed to have no idea of just how the news
of the moments of time gets to be rationed to consciousness in such
rigid doses.....Now consider the passage of time. Is there a
comparable reason in the known physics of space and time to dismiss it
as an illusion? I know of none. The only stimulus is a negative one.
We don't find passage in our present theories and we would like to
preserve the vanity that our physical theories of time have captured
all the important facts of time. So we protect our vanity by the
stratagem of dismissing passage as an illusion."

http://www.geekitude.com/gl/public_html/article.php?story=20050422141509987
Brian Greene: "I certainly got very used to the idea of relativity,
and therefore I can go into that frame of mind without it seeming like
an effort. But I feel and think about the world as being organized
into past, present and future. I feel that the only moment in time
that's really real is this moment right now. And I feel [that what
happened a few moments ago] is gone, and the future is yet to be. It
still feels right to me. But I know in my mind intellectually that's
wrong. Relativity establishes that that picture of the universe is
wrong, and if I work hard, I can force myself to recognize the fallacy
in my view or thinking; but intuitively it's still what I feel. So
it's a daily struggle to keep in mind how the world works, and
juxtapose that with experience that [I get] a thousand, even million
times a day from ordinary comings and goings."

Pentcho Valev wrote:

http://www.people.fas.harvard.edu/~djmorin/book.html
Introduction to Classical Mechanics
David Morin
Cambridge University Press
Chapter 11, p. 14: "Twin A stays on the earth, while twin B flies
quickly to a distant star and back. Show that B is younger than A when
they meet up again. Solution: From A's point of view, B's clock is
running slow by a factor gamma, on both the outward and return parts
of the trip. Therefore, B is younger than A when they meet up again.
This is the answer, and that's that. So if getting the right answer is
all we care about, then we can pack up and go home. But our reasoning
leaves one large point unaddressed. The "paradox" part of this
example's title comes from the following alternate reasoning. Someone
might say that in B's frame, A's clock is running slow by a factor
gamma, and so A is younger than B when they meet up again. It's
definitely true that when the two twins are standing next to each
other (that is, when they are in the same frame), we can't have both B
younger than A, and A younger than B. So what is wrong with the
reasoning at the end of the previous paragraph? The error lies in the
fact that there is no "one frame" that B is in. The inertial frame for
the outward trip is different from the inertial frame for the return
trip. The derivation of our time-dilation result applies only to one
inertial frame. Said in a different way, B accelerates when she turns
around, and our time-dilation result holds only from the point of view
of an inertial observer. (...) For the entire outward and return parts
of the trip, B does observe A's clock running slow, but enough
strangeness occurs during the turning-around period to make A end up
older. Note, however, that a discussion of acceleration is not
required to quantitatively understand the paradox, as Problem 11.2
shows."

The moment a rational scientist comes to find the following excerpt
consistent he becomes irrational, that is, he becomes a Believer:

"For the entire outward and return parts of the trip, B does observe
A's clock running slow, but enough strangeness occurs during the
turning-around period to make A end up older. Note, however, that a
discussion of acceleration is not required to quantitatively
understand the paradox, as Problem 11.2 shows."

http://www.haverford.edu/physics/songs/divine.htm
No-one's as dee-vine as Albert Einstein
Not Maxwell, Curie, or Bohr!
He explained the photo-electric effect,
And launched quantum physics with his intellect!
His fame went glo-bell, he won the Nobel --
He should have been given four!
No-one's as dee-vine as Albert Einstein,
Professor with brains galore!
No-one could outshine Professor Einstein --
Egad, could that guy derive!
He gave us special relativity,
That's always made him a hero to me!
Brownian motion, my true devotion,
He mastered back in aught-five!
No-one's as dee-vine as Albert Einstein,
Professor in overdrive!

http://www.youtube.com/watch?v=5PkLLXhONvQ
We all believe in relativity, relativity, relativity.
Yes we all believe in relativity, 8.033, 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, 8.033, relativity.

Pentcho Valev
pvalev@yahoo.com