NewScientist.com "Sacrificing Einstein: Relativity's keystone has to go"
WHY?
The
Only 'Keystone' and 'Sacrifice' Physics has to make is it’s “Flat World”
Interpretation of E=MC2
The odd force
Nothing doing
Anomalous accelerations
Drop the
subject
Dark
inertia
The Radius
of Curvature of all Natural Law:
How much longer will science avoid the obvious and remain in the “flat world” stage of a round world/universe concept of Physics? THE LAW IS CURVED, NOT THE SPACE. The quantity C is the kinetic energy equivalent of the mass energy of matter. http://fuel2000.net/starsteps2.pdf (Chapter 3)
How much longer will science avoid the obvious and remain in the “flat world” stage of a round world/universe concept of Physics? THE LAW IS CURVED, NOT THE SPACE. The quantity C is the kinetic energy equivalent of the mass energy of matter. http://fuel2000.net/starsteps2.pdf (Chapter 3)
In our discussion of non-linearity of physical law, it was pointed out that the energy inherent
in a gram, or any other quantity of matter is precisely the quantity of energy necessary
to accelerate its mass to a velocity equal to the quantity C by energy conversion. This statement may be hotly disputed by some
students who have not yet learned to distinguish between matter and mass. Their
argument is to the effect that no mass can ever be accelerated to the velocity
of light since the mass would then be 'infinite' and consequently the energy
required to produce the velocity would also be 'infinite'. The incorrectness of this assumption can be
demonstrated simply by pressing the button of a pocket flashlight. A beam of light will be produced which any physicist
will agree has mass and which, by its very definition, is moving at the
velocity of light. Yet all the energy required is released by a small amount of
chemical change taking place within the cells of a battery.
Our Expanding View of Energy
Our Expanding View of Energy
·
The George
Washington University’s Planet Forward: The Promise of Energy for Everyone
Video http://planetforward.org/idea/looking-to-nature-for-a-new-take-on-energy
A
Power Point Introductory Presentation http://www.relaxspa.net/TheRadiusOfCurvature12-28-10PPShow2003.pps
We interact with the concept of mass every day. Without it,
gravity wouldn't keep us firmly planted on Earth. But mass is also a component
of inertia, making it hard, for example, to push a stalled car.
On the surface, inertia and gravity don't seem to have much
in common. But in experiments, these two versions of mass always give the same
results. Although we've been aware of the coincidence since Galileo's day, the
only explanation, proposed by Einstein, has been much disputed.
In this video, we delve into the split personality of mass,
exposing the conundrum that lies at the core of one of the most basic concepts
in physics. For more on the topic, read our full-length feature article, "Sacrificing Einstein: Relativity's
keystone has to go".
Our hopes
of finding a theory of everything depend on upsetting a balance that Einstein
cherished
COINCIDENCE is not generally something scientists have much truck
with. If two things are genuinely unrelated, there is little further of
interest to be said. If the coincidence keeps turning up, however, there must
be some deeper underlying link. Then it is the job of science to tease out what
it is and so explain why there was no coincidence in the first place.
That makes
it rather odd that a large chunk of modern physics is precariously balanced on
a whopping coincidence.
This coincidence is essential to
the way we view and define mass. It is so fundamental to the world's workings
that most of us encounter its consequences every day without giving them
another thought. Yet it has vexed some of the best minds in physics for centuries.
Galileo and Newton grappled with it, and ended up just accepting it, rather
than understanding it. Einstein went one better: he declared it a principle of
nature. He went on to use this "equivalence principle" as the
fundament of his general theory of relativity,
still our best stab at explaining the mysterious force of gravity.
But there is a problem. If we want to find some bigger, better
theory that can unify gravity with the other forces that dictate the world's
workings, the equivalence principle cannot stay. We must either unmask this
coincidence - or radically rethink how physics can progress from here.
There are several versions of the
equivalence principle, but all boil down to one idea: that the effects of
gravitational fields are indistinguishable from the effects of accelerated
motion. A thought experiment of Einstein's expresses it best. Imagine a person
standing inside an elevator on Earth. What keeps their feet firmly planted on
the floor? The inexorable pull of gravity downwards, of course. Now imagine the
same person in the same lift, but in empty space far from any gravitating
object. In this case a rocket just so happens to be pushing the lift up in
empty space with the same acceleration that Earth's gravity produces. The
passenger will remain squarely on the lift floor in exactly the same way (see "An enigmatic equivalence").
How so, when there is no gravity involved? In this case, it is the
person's inertia that is preventing them floating upwards. Inertia is the
natural resistance of any body to acceleration - the same effect that pushes
you back into your car seat when the driver puts their foot down.
The two elevator situations have a common property, mass. But the
two masses come from very different places. One, gravitational mass, is
something that responds to the pull of gravity, tending to accelerate a body in
a gravitational field. The other, inertial mass, is the property of a body that
opposes any acceleration.
Another way of stating the equivalence principle is to say that
these two masses are always numerically exactly the same. The consequences of
this coincidence are profound. If the two masses weren't the same, objects of
different masses could fall to Earth at different rates, rather than all
accelerating in the same way in a gravitational field. This "universality
of freefall" was apocryphally first tested by Galileo dropping a bag of
feathers and a bag of lead shot from the Leaning Tower of Pisa. In fact, the
equality of gravitational and inertial mass dictates all gravitational motion
throughout the universe. If gravitational mass responded just a little bit more
to gravity than inertial mass does to acceleration, for example, then planets
would orbit their stars and stars orbit their galaxies just a little bit faster
than they do.
Yet there is no obvious reason why this correspondence should be
so. It was only by assuming it was that Einstein fully developed the strange
contortions and contractions of time and space he had first introduced in his
special theory of relativity in 1905. What if a massive object such as a
planet, Einstein wondered, squeezes the surrounding space into successively
more compact volumes the closer you get to it? As something moved towards the
planet's surface, it would then take less and less time to cross these
compacted spaces: it would appear to accelerate.
The odd force
By 1916, this thought had guided Einstein to his general theory of
relativity. What looks like gravity is just uniform motion through a
progressively compacted space. And if there is no gravity, gravitational mass
is fictitious too. The only mass at work in the universe is the one that gives
a body its inertia. The coincidence behind equivalence disappears.
General relativity is, as far as we have tested it, peerlessly
accurate, predicting the positions of celestial bodies and guiding our
satellites with minute precision. Yet there is something odd about it that
physicists don't like. All the other forces of nature are transmitted between
bodies by physical, if ethereal, quantum particles. The electromagnetic force,
for example, is transmitted between bodies with electrical charge by the
exchange of the massless particles called photons. Outwardly, gravity works in
exactly the same way. It looks like a duck, swims like a duck - but it can't
quite be made to quack like a duck.
Attempts to make gravity quack
with a quantum voice are the guiding thought behind string theory and other projects to construct all-embracing "theories of
everything". But if gravity is to be reborn as a real force, it
needs something to latch on to, just as electromagnetism latches on to electric
charge. It needs a gravitational mass that is separate and distinct from
inertial mass.
That means progress towards a
theory of everything has an essential first step: slaying Einstein's holy cow.
"Any theory of quantum gravity must violate the equivalence principle at
some level," says Ben Gripaios, a theoretical
physicist at the University of Cambridge.
How? One tried and tested method
is to attempt to prove that the two masses aren't actually equivalent at all -
just very, very close. Even the slightest sliver of a difference would mean
that general relativity is built on an approximation and that a deeper, more
precise theory must exist. "If someone finds a difference then we have
made a major breakthrough," says Claus Lämmerzahlof
the University of Bremen in Germany.
A way to do this is to continue
on in the spirit of Galileo's Leaning Tower experiments, testing the
universality of free fall and other consequences of the equivalence principle
in the hope of teasing out some tiny anomaly - so far with little success (see "Drop the subject").
Meanwhile, theorists are picking at a different thread. They point out that
whether or not Einstein was right about there being no gravity, just inertia,
no one has yet come up with a convincing explanation of inertia. "We do
not yet know how to define it," says Gripaios. "We know it must be
related closely to mass, but until we can define it precisely and know how to
measure it, there can be no theory for it."
One thing's for sure: it doesn't
all come from the Higgs field, feted as the giver of mass.
Evidence for the existence of this field and its associated particle was
presented by physicists sifting through the debris of particle collisions at
the Large Hadron Collider at CERN near Geneva, Switzerland, last
year. But while the Higgs field is thought to give fundamental particles such
as electrons and quarks their mass, when quarks combine into the heavier
particles, protons and neutrons, that make up the bulk of normal matter, the
resulting mass is roughly a thousand times the summed mass of the constituent
quarks. This extra mass comes not from the Higgs mechanism, but from the energy
needed to keep the quarks together. Somehow, these two effects must combine and
latch on to something else to create the property of a body's resistance to
acceleration. "There is no way the Higgs alone can be some sort of
mysterious ingredient that gives inertia," says Gripaios.
What then? One suggestion has its
origins in work by Stephen Hawking in the 1970s. Ironically, it was
motivated back then by a strict application of the equivalence principle.
Hawking was investigating the properties of black holes, the unimaginably dense
gravitating bodies whose existence is a central prediction of general
relativity. He suggested that a black hole should be an apparent source of
radiation, because pairs of quantum particles that constantly pop up in space
would become separated close to a black hole, with one being sucked in and the
other spat out. That led the Canadian physicist William Unruh and
others to suggest that, if gravitation and acceleration really are one and the
same thing, similar emissions should be a feature of any body accelerating in a
vacuum.
Nothing doing
Like Hawking's radiation,
Unruh's has never been unambiguously detected. The accelerations necessary to
achieve a measurable effect in a lab are generally too high, although some argue the effect has been seen with electrons accelerated in the high
magnetic fields of particle accelerators.
A decade or so on from Unruh's original
work, astrophysicist Bernard Haischof the Max Planck Institute for
Extraterrestrial Physics in Garching, Germany, and electrical engineer Alfonso Rueda of California State University in Long
Beach were playing with a similar idea when they realised the vacuum's
interaction with an accelerating body would not just occur on its surface, but
permeate its entire volume. That could produce a force that acts in the
opposite direction to the body's movement. They originally likened it to the
way in which charged particles moving through a magnetic field experience a
force - the Lorentz force - that affects their motion. In this case there were
electromagnetic interactions with the quantum vacuum. "It appears to be
exactly what you need for inertia," says Haisch.
Anomalous accelerations
Mike McCulloch of
the University of Plymouth, UK, thinks such interactions are also just what you
need to break the equivalence principle. One prediction made of Unruh radiation
is that, like the rays emitted from a hot body, it comes in a spectrum of many
different wavelengths. For very small accelerations, the temperature of the
radiation that a body "sees" from the vacuum is low, and dominated by
very long wavelengths. Make the acceleration very small indeed, and some of
these wavelengths become longer than the size of the observable universe,
effectively cutting them off.
In this case, according to calculations McCulloch did in
2007, originally to explain the seemingly anomalous
accelerations of the Pioneer spacecraft as they crossed the solar system, the
total amount of Unruh radiation experienced by a body would drop, and it would
feel less of an opposing force. Its inertia would thus fall, making it easier
to move than Newton's standard laws of motion dictate - and cutting the
connection with gravitational mass.
The problem with this idea is
testing it. In the high-gravity environment of Earth, accelerations small
enough for the effect to be observed would not be easy to manufacture. But its
effects might well be seen in a low-gravity environment such as that found at
the edge of a galaxy. Indeed, looking at the anomalous motions of most spiral
galaxies, McCulloch suggests this mechanism could also explain another enduring
cosmic mystery - that of dark matter (see "Dark inertia").
It's fair to say such ideas have not set the world alight. When
Haisch and Rueda came up with their mechanism, NASA was sufficiently impressed
to fund further study and the duo also attracted some $2 million in private
investment. But the lack of testable predictions of how the effect might
manifest itself led the money and interest to dry up.
Nevertheless, a traditionalist such as Lämmerzahl thinks we should
not dismiss the idea out of hand. "Even though I follow more the ideas of
string theory, these ideas of vacuum interactions are not nonsense," he
says. "We need to look at them seriously and decide whether they give us
new ways to test the equivalence principle."
One proposal to do that was made
in 2010 by a trio of Brazilian astronomers led by Vitorio De Lorenci of the
Federal University of Itajubá. They suggestedusing a spinning disc to cancel
out the accelerations produced by Earth's rotation and its movement through space. At
minuscule accelerations, the disc's inertia would drop, meaning it would spin
faster than expected from Newton's laws. Despite a relatively modest cost,
however, no money has yet been forthcoming to fund the experiment.
And so the deadlock remains until someone delivers either an
experiment that exposes the equivalence principle as a sham, or a theoretical
idea that shows why it must be just so. But if in the end gravitational mass is
indeed just inertial mass in another guise - whatever inertial mass is - then
it will be the quantum theories of gravity, including string theories, that
will find themselves laid upon the sacrificial altar. Paths to a theory of
everything will become even more winding. If gravity is not a force, but truly
an illusion that springs from the warping of space, as described by general
relativity, we will have to look more closely to understand at a basic level
what makes that warping come about.
Just a coincidence? This is one that science is not finding so
easy to dismiss.
Drop the
subject
Looming
146 metres over the north German plain like a great white rocket poised for
take-off, it's hard to ignore the University of Bremen's "drop
tower". Inaugurated in 1990 as part of the Center of Applied Space Technology and Microgravity (ZARM),
it provides up to 9.3 seconds of free fall in which to conduct experiments (see photo). So far
tests of rubidium and potassium atoms in free fall have provided no deviation
from the behaviour predicted by the equivalence principle (see main story). The
atoms have been found to fall at the same rate to accuracies of 11 decimal places.
At the
University of Washington in Seattle, meanwhile, Eric Adelberger and his "Eöt-Wash" team
use a high-tech set of scales known as a torsion balance to compare the motions
of standard masses made of different elements, including copper, beryllium,
aluminium and silicon. They hold the record for test accuracy, with no
violations of the equivalence principle to 13 decimal places.
At some
point, however, these earthbound experiments are going to hit a brick wall.
"It is getting harder to make the instruments better," says
Adelberger. Working somewhere where gravity is a lot smaller would make any
deviations from equivalence a lot easier to spot. The French-led MICROSCOPE mission
due to launch in 2016 will do just that, testing the motions of masses of
platinum and iridium in the microgravity conditions of space. "MICROSCOPE
will achieve an accuracy 100 times better than a laboratory on Earth,"
says Claus Lämmerzahl of ZARM.
His
organisation is testing the satellite's accelerometers in their drop tower, and
also developing the software needed to analyse the satellite's final results.
An even more sensitive mission, the Space-Time Explorer and Quantum
Equivalence Principle Space Test, is currently being evaluated by
the European Space Agency, with a decision on funding due by the end of this
year.
Dark
inertia
In the 1930s, we noticed that
galaxies spinning around other galaxies were not moving as Newton's and
Einstein's laws of gravity dictated. A few decades later, something similar was
observed of the rotation of individual spiral galaxies. It was almost as if
some invisible matter was whirling the matter we could see around faster.
That idea has now become
mainstream: standard cosmology textbooks will tell you that "dark
matter" outweighs normal matter by a factor of 5 to 1. Yet despite
particle physicists supplying an almost endless list of hypothetical particles
that might fit the bill, to date none has been definitively detected.
An
alternative first championed in the 1980s by Mordehai Milgrom, a physicist then
at Princeton University, is that gravity must somehow be modified at a galaxy's
edges. This could be explained if there was a drop in inertial mass without a
drop in gravitational mass for stars experiencing the ultra-low accelerations found
at the outskirts of galaxies. This would naturally make them move faster. If
vacuum interactions can really bring this about (see main story), they could be
just the ticket to mimic dark matter.
Stuart Clark is a consultant to New Scientist and the author of The Sky's Dark Labyrinth trilogy (Polygon)
