Quoting from Alan Lightman's, "A Modern Day Yankee In A
Connecticut Court and other essays on Science".
Conversations with Papa Joe
The Forth Evening
Key Words and Phrases:
Equation can describe the behavior of time, space, matter and energy.
Newton's laws, thermodynamics
Quantum Mechanics --
Summary of Important Ideas in Quantum Physics
Simplicity, intuition, guesses.
GR Predicted BH
Gravitational Time Dilation
Space and time are malleable
Tests of GR (Solar Eclipses 1919, 1922)
Sirius, Hunter, Constellations
Perhaps the most powerful aspect of physics, and indeed
perhaps the most amazing thing about the cosmos as a whole,
is the universality of physical laws and theories.
A few scant equations small enough to fit on your favorite
T-shirt can explain a variety of phenomena from one edge of
the universe to the other, and from the earliest moments of
the Big Bang to the unfathomable future.
Five Papers That Shook the World
ON THE ELECTRODYNAMICS OF MOVING BODIES By A. Einstein
Wikipedia - General relativity
General relativity (GR), also known as the general theory of
relativity (GTR), is the geometric theory of gravitation
published by Albert Einstein in 1915 and is the current
description of gravitation in modern physics. General
relativity generalizes special relativity and refines
Newton's law of universal gravitation, providing a unified
description of gravity as a geometric property of space and
time or four-dimensional spacetime. In particular, the
curvature of spacetime is directly related to the energy and
momentum of whatever matter and radiation are present. The
relation is specified by the Einstein field equations, a
system of partial differential equations.
Documentary: Life of Albert Einstein (90 min) Start at 1:22:45
Beautiful, Simple and Profound -- Final Development and Testing GR
Beautiful, Simple and Profound -- Classical Tests of Relativity
Beautiful, Simple and Profound -- Modern Tests of Relativity
Beautiful, Simple and Profound -- Detection of Gravitational Waves
Black Holes -- Prediction, Properties, and Structure
Black Holes -- Formation, Evolution, and Hawking Radiation
Black Holes -- Observational Evidence
Black Holes -- Open Questions
Einstein's description of gravity just got much harder to beat
Einstein's theory of general relativity-the idea that
gravity is matter warping spacetime-has withstood over 100
years of scrutiny and testing, including the newest test
from the Event Horizon Telescope collaboration, published
today in the latest issue of Physical Review Letters.
According to the findings, Einstein's theory just got 500
times harder to beat.
Despite its successes, Einstein's robust theory remains
mathematically irreconcilable with quantum mechanics, the
scientific understanding of the subatomic world. Testing
general relativity is important because the ultimate theory
of the universe must encompass both gravity and quantum
Summary of Important Ideas in Quantum Physics
Heisenberg's uncertainty principle
http://www.youtube.com/watch?v=a8FTr2qMutA (4+ min)
Heisenberg's uncertainty principle tells us that it is
impossible to simultaneously measure the position and
momentum of a particle with arbitrary precision. In our
everyday lives we virtually never come up against this
limit, hence why it seems peculiar. In this experiment a
laser is shone through a narrow slit onto a screen. As the
slit is made narrower, the spot on the screen also becomes
narrower. But at a certain point, the spot starts becoming
wider. This is because the photons of light have been so
localized at the slit that their horizontal momentum must
become less well defined in order to satisfy Heisenberg's
Quantum vacuum fluctuation (or Quantum Fluctuation for short)
Quoting from the above Wikipedia page:
"In quantum physics, a quantum vacuum fluctuation (or
quantum fluctuation or vacuum fluctuation) is the temporary
change in the amount of energy in a point in space, arising
from Werner Heisenberg's uncertainty principle.
"According to one formulation of the principle, energy and
time can be related by the relation
"That means that conservation of energy can appear to be
violated, but only for small times. This allows the creation
of particle-antiparticle pairs of virtual particles. The
effects of these particles are measurable, for example, in
the effective charge of the electron, different from its
"In the modern view, energy is always conserved, but the
eigenstates of the Hamiltonian (energy observable) are not
the same as (i.e., the Hamiltonian doesn't commute with) the
particle number operators.
"Quantum fluctuations may have been very important in the
origin of the structure of the universe: according to the
model of inflation the ones that existed when inflation
began were amplified and formed the seed of all current
Quoting from A USENET Posting by Steve Carlip (UC Davis):
"CMB fluctuations give evidence for (though not proof of)
"So far, I haven't said anything about where the initial
density variations of the pre-recombination plasma came
from. There are many possibilities. We know, at least, that
they must be there -- even if we try to start with a
perfectly smooth, unvarying plasma, the Heisenberg
uncertainty principle tells us that there must be a minimum
level of quantum fluctuations.
"Inflationary" models propose that the very early Universe
-- before the time of primordial nucleosynthesis --
underwent a very rapid expansion. Such an expansion would
smooth out/dilute any earlier inhomogeneities, leaving only
the quantum fluctuations, which would be "stretched" in size
by the rapidly expanding space.
"Such models predict a special pattern of fluctuations. In
particular, although any particular fluctuation is random,
the average number at any particular scale is predictable.
This pattern on initial variations, in turn, should show up
in the details of the CMB variations. So far, observations
match the predictions of inflation very well. Most people in
the field don't consider this conclusive -- one can imagine
other ways of getting a similar pattern of initial
perturbations -- but it is suggestive."
In physical cosmology, cosmic inflation, cosmological
inflation, or just inflation is the extremely rapid
exponential expansion of the early universe by a factor of
at least 10^78 in volume, driven by a negative-pressure
vacuum energy density. The inflationary epoch comprises the
first part of the electroweak epoch following the grand
unification epoch. It lasted from 10^-36 seconds after the
Big Bang to sometime between 10^-33 and 10^-32 seconds.
Following the inflationary period, the universe continued to
expand, but at a slower rate.
The term "inflation" is also used to refer to the hypothesis
that inflation occurred, to the theory of inflation, or to
the inflationary epoch. The inflationary hypothesis was
originally proposed in 1980 by American physicist Alan Guth,
who named it "inflation". It was also proposed by Katsuhiko
Sato in 1981.
As a direct consequence of this expansion, all of the
observable universe originated in a small causally connected
region. Inflation answers the classic conundrum of the Big
Bang cosmology: why does the universe appear flat,
homogeneous, and isotropic in accordance with the
cosmological principle when one would expect, on the basis
of the physics of the Big Bang, a highly curved,
heterogeneous universe? Inflation also explains the origin
of the large-scale structure of the cosmos. Quantum
fluctuations in the microscopic inflationary region,
magnified to cosmic size, become the seeds for the growth of
structure in the universe (see galaxy formation and
evolution and structure formation).
Why did Alan Guth say "the universe may be the ultimate free
Alan Guth is the first and main father of inflationary
cosmology, see e.g. Alan Guth and inflation.
His comment about the "universe as the ultimate free lunch"
is an explanation of a striking feature of inflationary
cosmology. During cosmic inflation, the Universe is created
basically from nothing.
The energy conservation law and the mass conservation law
are explicitly violated in cosmology as modernized by
Einstein's general theory of relativity and Guth's (and
Linde's) cosmic inflation makes this violation maximum.
During inflation, the volume of the Universe - e.g. the
volume of a tetrahedron between four (newborn or future)
galaxies - increases exponentially with cosmic time.
Nevertheless, the density of mass or energy in that
tetrahedron is basically constant during inflation. So the
total mass/energy increases exponentially, just like the
At some moment, the inflationary epoch ends and the energy
produced in the Universe "out of nothing" is converted to
particles that give rise to the seeds of galaxies as we know
There is a proverb that there's never any free lunch.
Everything costs something, everything is a trade-off, and
so on. Alan Guth pointed out that the model of the expansion
of the very early Universe that he discovered is the
greatest counterexample to that proverb and wisdom - because
there actually is a completely free lunch. The Universe,
essentially all the matter in it, was created (almost) out
The Stars: A New Way to See Them
by H. A. Rey
This book contains the most lucid explanation of the
sidereal day I have ever read. If you are looking for a book
that explains the big bang theory and modern astronomical
theories, this is not your book. If you are want to look up
at the sky and recognize stars like old friends, then this
is your book.
Along the way, you will learn enough about the relative
motions of the earth, sun, planets and stars to understand
why different parts of the sky are visible at different
times of the year, and from various places on earth.
365 Starry Nights; An introduction to Astronomy for every
night of the year
by Chet Raymo
365 Starry Nights is a unique and fascinating introduction
to astronomy designed to give you a complete, clear picture
of the sky every night of the year. Divided into 365
concise, illustrated essays, it focuses on the aesthetic as
well as the scientific aspects of stargazing. It offers the
most up-to-date information available, with hundreds of
charts, drawings, and maps-that take you beyond the visible
canopy of stars and constellations into the unseen realm of
nebulae and galaxies.
This simple yet substantial text is full of critical
information and helpful hints on how to observe the stars;
describe their position; calculate their age, brightness,
and distance; and much more. Whether you observe the sky
with a telescope or the naked eye, 365 Starry Nights makes
the infinite intimate and brings the heavens within your
grasp. Keep this invaluable, informative guide close at
hand, and you'll find that the sky is the limit 365 nights a
The Equations: Icons of Knowledge
by Sander Bais
An intriguing little book...founded on a quarrel with what
the author calls the 'fashionable dogma' of not including
equations in science books intended for general readers.
'The veto is like asking somebody to explain art without
showing pictures,' Bais argues. And he's right. His book is
worth a look for anyone feeling brave enough to journey into
the language of physical science on its own ground: the
terra firma of mathematics. --Anthony Doerr (Boston Globe
The author writes clearly and incisively about the physical
ideas...Most books of this genre take it as axiomatic that
they must avoid equations. Bais embraces them, building his
book around the equations of physics and using them as the
vehicle for describing the counter-intuitive world of
relativity theory, quantum mechanics, and string theory.
--David M. Bressoud (Mathematical Association of America)
Let me say at once that I learnt a great deal from the
author's broad-brush approach...The physics is very
readable, with connections between different parts of the
subject made well. And because the book is so short, the
reader has a real chance to see "the big picture"...There is
no doubt that The Equations is a bold and original book.
And, in my view, imagination of this kind will be needed in
the future if maths and science education is to avoid
sliding gradually into lightweight stuff about what Newton
ate for breakfast. --David Acheson (Times Higher Education
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