Einstein's Physics Of Illusion

Some of you may think from the title "Einstein's Physics of Illusion", that I'm going to talk about the
physics which underlies what we think of as magic. That is not what I expect to talk about. Some of you
may think that I suspect that Einstein had some special physics of illusions. If he did, I don't know
anything of it. Instead, what I want to do, with Einstein's help, is to trace our physics all the way back to
square one, and to find out whether, underlying it, there may possibly be something akin to magic.
George Valens has written a charming book called The Attractive Universe. It is subtitled "Gravity and
the Shape of Space", and on the very first page he says that when a ball is thrown straight up, after a
while it comes to a stop, changes its direction and comes back. He says it looks like magic, and probably
it is. Now what he is taking for granted is that it should have gone off on a straight path without any
change in speed or direction. But you see, that also would have been the result of magic. We do not
understand in physics why the ball comes back. But we also do not understand in our physics why the
ball should have continued without any change in the direction of its speed....

A Brief History of Black Holes

It has frequently been alleged by theoretical physicists Newton’s theory of gravitation either predicts or adumbrates the black hole. This claim stems from a suggestion originally made by John Michell in 1784 that if a body is sufficiently massive, “all light emitted from such a body would be made to return to it by its own power of gravity”. The great French scientist, P. S. de Laplace, made a similar conjecture in the eighteenth century and undertook a mathematical analysis of the matter. However, contrary to popular and frequent expert opinion, the Michell-Laplace dark body, as it is actually called, is not a black hole at all. The reason why is quite simple. For a gravitating body we identify an escape velocity.

This is a velocity that must be achieved by an object to enable it to leave the surface of the host body and travel out to infinity, where it comes to rest.

Black Holes

After a star has exhausted its nuclear fuel, it can no longer remain in equilibrium and
must ultimately undergo gravitational collapse. The star will end as a white dwarf
if the mass of the collapsing core is less than the famous Chandrashekhar limit of 1.4
solar masses. It will end as a neutron star if the core has a mass greater than the
Chandrashekhar limit and less than about 35 times the mass of the sun. It is often
believed that a core heavier than about 5 solar masses will end, not as a white dwarf
or as a neutron star, but as a black hole. However, this belief that a black hole will
necessarily form is not based on any firm theoretical evidence. An alternate possibility
allowed by the theory is that a naked singularity can form, and the purpose of the
present article is to review our current understanding of gravitational collapse and the
formation of black holes and naked singularities.
A black hole has been appropriately described by Chandrashekhar as the most
beautiful macroscopic object known to man. Only a few parameters suffice to describe
the most general black hole solution, and these objects have remarkable thermodynamic
properties. Further, excellent observational evidence for their existence has
developed over the years (Rees 1998). Thus, there can be no doubt about the reality of
black holes, and the gravitational collapse of very many sufficiently massive stars
must end in the formation of a black hole...

Visual Quantum Mechanics The Next Generation

A large number of devices detect the presence of light. These range from the “switches”
which automatically turn on the street lights when it gets dark to the receiving end of the
scanners at the grocery store check out counter to the detectors in a CD player. All of
these devices work because light striking a material deposits energy in that material and
causes a change in the motion of the electrons. The detection of this change helps determine
how dark it is, how much your potato chips cost, and what sound should be produced
by the stereo.
The basic process behind all of these devices is the photoelectric effect. This effect was
first explained by Albert Einstein in 1905 and is cited as the reason for his Nobel Prize.
(When Einstein was awarded the Noble Prize, the Theory of Relativity was very controversial,
so it was not included as the reason.) We will study this photoelectric effect in this
experiment....

"Ether and the Theory of Relativity"

HOW does it come about that alongside of the idea of ponderable matter, which is derived by abstraction from everyday life, the physicists set the idea of the existence of another kind of matter, the ether? The explanation is probably to be sought in those phenomena which have given rise to the theory of action at a distance, and in the properties of light which have led to the undulatory theory. Let us devote a little while to the consideration of these two subjects.
Outside of physics we know nothing of action at a distance. When we try to connect cause and effect in the experiences which natural objects afford us, it seems at first as if there were no other mutual actions than those of immediate contact, e.g. the communication of motion by impact, push and pull, heating or inducing combustion by means of a flame, etc. It is true that even in everyday experience weight, which is in a sense action at a distance, plays a very important part. But since in daily experience the weight of bodies meets us as something constant, something not linked to any cause which is variable in time or place, we do not in everyday life speculate as to the cause of gravity, and therefore do not become conscious of its character as action at a distance.....

Mysteries of the Universe

There are few scientists of whom it can be said that their mistakes are more interesting
than their colleagues' successes, but Albert Einstein was one. Few "blunders" have had a
longer and more eventful life than the cosmological constant, sometimes described as the
most famous fudge factor in the history of science, that Einstein added to his theory of
general relativity in 1917. Its role was to provide a repulsive force in order to keep the
universe from theoretically collapsing under its own weight. Einstein abandoned the
cosmological constant when the universe turned out to be expanding, but in succeeding
years, the cosmological constant, like Rasputin, has stubbornly refused to die, dragging
itself to the fore, whispering of deep enigmas and mysterious new forces in nature,
whenever cosmologists have run into trouble reconciling their observations of the
universe with their theories.
This year the cosmological constant has been propelled back into the news as an
explanation for the widely reported discovery, based on observations of distant exploding
stars, that some kind of "funny energy" is apparently accelerating the expansion of the
universe. "If the cosmological constant was good enough for Einstein," the cosmologist
Michael Turner of the University of Chicago remarked at a meeting in April, "it should
be good enough for us."
Einstein has been dead for 43 years. How did he and his 80-year-old fudge factor come to
be at the center of a revolution in modern cosmology?
The story begins in Vienna with a mystical concept that Einstein called Mach's principle.
Vienna was the intellectual redoubt of Ernst Mach (1838-1916), a physicist and
philosopher who bestrode European science like a Colossus. The scale by which
supersonic speeds are measured is named for him. His biggest legacy was philosophical;
he maintained that all knowledge came from the senses, and campaigned relentlessly
against the introduction of what he considered metaphysical concepts in science, atoms
for example.
Mysteries of the Universe

Another was the notion of absolute space, which formed the framework of Newton's
universe. Mach argued that we do not see "space," only the players in it. All our
knowledge of motion, he pointed out, was only relative to the "fixed stars." In his books
and papers, he wondered if inertia, the tendency of an object to remain at rest or in
motion until acted upon by an outside force, was similarly relative and derived somehow
from an interaction with everything else in the universe.
"What would become of the law of inertia if the whole of the heavens began to move and
stars swarmed in confusion?" he wrote in 1911. "Only in the case of a shattering of the
universe do we learn that all bodies, each with its share, are of importance in the law of
inertia.".....

The Speed of Light

The approximate speed of light was already known to us back in the time of Isaac Newton. Astronomers were able to use the rotation of planets and their moons as an incredibly precise system of "clockwork", and the precision of these measurements was so exact that they could identify the changes in apparent timings caused by light taking longer to reach us from more distant parts of the solar system. The critical measurement was that of the eclipse of the moons of Jupiter -- Roemer noted that the eclipses were seen slightly earlier when Jupiter was nearer to us, and slightly later when the planet was further away.
Newton's quoted estimates in Opticks of light taking seven or eight minutes to reach us from the Sun, along with an estimated distance of the Sun of seventy million miles, would have given an estimated speed of light of 150,000-160,000 miles per second. More modern values of a bit over eight minutes (~500 seconds) and just over 93 million miles give us a speed of around 186,000 miles per second, so the old figures weren't that far off
James Maxwell's work on electricity and magnetism in the mid-Nineteenth Century then led to a prediction of the existence of electromagnetic waves that just happened to propagate at the same speed as light. Maxwell argued that light was an electromagnetic wave, and that visible light consisted of electromagnetic radiation whose wavelengths happened to be in a suitable range for human eyes to be able to detect it.
Maxwell's work suggested that the speed of light should be constant, but didn't tell us exactly what sort of lightspeed constancy ought to be involved.....

"Relativity and the Problem of Space"

IT is characteristic of Newtonian physics that it has to ascribe independent and real existence to space and time as well as to matter, for in Newton's law of motion the idea of acceleration appears. But in this theory, acceleration can only denote "acceleration with respect to space". Newton's space must thus be thought of as "at rest", or at least as "unaccelerated", in order that one can consider the acceleration, which appears in the law of motion, as being a magnitude with any meaning. Much the same holds with time, which of course likewise enters into the concept of acceleration.
Newton himself and his most critical contemporaries felt it to be disturbing that one had to ascribe physical reality both to space itself as well as to its state of motion; but there was at that time no other alternative, if one wished to ascribe to mechanics a clear meaning.
It is indeed an exacting requirement to have to ascribe physical reality to space in general, and especially to empty space. Time and again since remotest times philosophers have resisted such a presumption. Descartes argued somewhat on these lines: space is identical with extension, but extension is connected with bodies; thus there is no space without bodies and hence no empty space. The weakness of this argument lies primarily in what follows. It is certainly true that the concept extension owes its origin to our experiences of laying out or bringing into contact solid bodies. But from this it cannot be concluded that the concept of extension may not be justified in cases which have not themselves given rise to the formation of this concept. Such an enlargement of concepts can be justified indirectly by its value for the comprehension of empirical results.
The assertion that extension is confined to bodies is therefore of itself certainly unfounded. We shall see later, however, that the general theory of relativity confirms Descartes' conception in a roundabout way.
What brought Descartes to his remarkably attractive view was certainly the feeling that, without compelling necessity, one ought not to ascribe reality to a thing like space, which is not capable of being "directly experienced"......