Inflation Model Seriously Challenged

What do you think of the following?

Is the Universe Out of Tune? by Glenn D. Starman, Dominik J.
Schwarz Scientific American August 2005

"IMAGINE a fantastically large orchestra playing expansively for
14 billion years. At first, the strains sound harmonious. But
listen more carefully: something is off key. Puzzlingly, the tuba
and bass are softly playing a different song.

So it is when scientists "listen" to the music of the cosmos
played in the cosmic microwave background (CMB) radiation, our
largest-scale window into the conditions of the early universe.
Shortly after the big bang, random fluctuationsprobably thanks to
the actions of quantum mechanics - apparently arose in the energy
density of the universe. They ballooned in size and ultimately
became the galaxy clusters of today. The fluctuations were a lot
like sound waves (ordinary sound waves are oscillations in the d
ensity of air), and the "sound" ringing throughout the cosmos 14
billion years ago was imprinted on the CMB. Now we see a map of
that sound drawn on the sky in the form of CMB temperature
variations.

As with a sound wave, the CMB fluctuations can be analyzed by
splitting them into their component harmonics-like a collection
of pure tones of different frequencies or, more picturesquely,
different instruments in an orchestra. Certain of those harmonics
are playing more quietly than they should be. In addition, the
harmonies are aligned in strange waysthey are playing the wrong
tune. These bum notes mean that the otherwise very successful
standard model of cosmology is flawed-or that something is amiss
wit h the data.

Scientists have constructed and corroborated the standard model
of cosmology over the past few decades. It accounts for an
impressive array of the universe's characteristics. The model
explains the abundances of the lightest elements (various
isotopes of hydrogen, helium and lithium) and gives an age for
the universe (14 billion years) that is consistent with the
estimated ages of the oldest known stars. It predicts the
existence and the near homogeneity of the CMB and explains how
many other properties of the universe came to be just the way
they are.

Called the inflationary lambda cold dark matter model, its name
derives from its three most significant components: the process
of inflation, a quantity called the cosmological constant
symbolized by the Greek letter lambda, and invisible particles
known as cold dark matter.

According to this model, inflation was a period of tremendously
accelerated growth that started in the first fraction of a second
after the universe began and ended with a burst of radiation.
Inflation explains why the universe is so big, so full of stuff
and so close to being homogeneous. It also explains why the
universe is not precisely homogeneous. because random quantum
fluctuations in the energy density were inflated up to the size
of galaxy clusters and larger.

The model predicts that after inflation terminated, gravity
caused the regions of extra density to collapse in on themselves,
ultimately forming the galaxies and clusters we see today. That
process had to have been helped along by cold dark matter, which
is made up of huge clouds of particles that are detectable only
through their gravitational effects. The cosmological constant
(lambda) is a strange form of antigravity responsible for the
present speedup, of the cosmic expansion [see "A Cosmic
Cortundrurn, " by Lawrence M. Krauss and Michael S. Turner;
SCIENTIFIC AMERICAN, September 2004.

The Most Ancient Light

Despite the Model's great success at explaining all those
features of the universe, problems show up when astronomers
measure the CMB's temperature fluctuations. The CMB is
cosmologists' most important probe of the largestscale properties
of the universe. It is the most ancient of all light, originating
only a few hundred thousand years after the big bang, when the
rapidly expanding and cooling universe made the transition from
dense opaque plasma to transparent gas. In transit for 14 billion
years, the CMB thus reveals a picture of the early universe.
Coming from the farthest reaches, that picture is also a snapshot
of the universe at its largest size scale.

Arno Penzias and Robert Wilson of Bell Laboratories first
detected the CMB and measured its temperature in 1965. More
recently, the cutting edge of research has been studies of
fluctuations in the temperature as seen when viewing different
areas of the sky. (Technically, these fluctuations are called
temperature anisotropies.) The differences in temperature across
the sky reflect the universe's early density fluctuations. In
1992 the COBE (Cosmic Background Explorer) satellite first
observed those fluctuati ons; later, the WMAP (Wilkinson
Microwave Anisotropy Probe) satellite has made high-resolution
maps of them.

Models such as the lambda cold dark matter model cannot calculate
the exact pattern of the fluctuations. Yet they can predict their
statistical properties, similar to predicting their average size
and the range of sizes they span. Some of these statistical
features are predicted not only by the lambda cold dark matter
model but also by numerous other simple inflationary models that
physicists have considered at one time or another as possible
alternatives. Because such properties arise in many different inf
lationary models, they are considered "generic" predictions of
inflation; if inflation is true at all, these predictions hold
irrespective of the finer details of the model. To falsify one of
them would be to challenge the scenario of inflation in the most
serious way a scientific theory can be challenged. That is what
the anomalous CMB measurements may do.

The predictions are best expressed by first breaking down the
temperature fluctuations into a spectrum of modes called
spherical harmonics, much as sound can be separated into a
spectrum of notes [see box on page 411. As mentioned earlier, we
can consider the density fluctuations, before they grow into
galaxies, to be sound waves in the universe. If this breakdown
into modes seems mysterious, recall the orchestra analogy: each
mode is a particular instrument, and the whole map of
temperatures across the sph ere of the sky is the complete sound
produced by the orchestra.

The first of inflation's generic predictions about the
fluctuations is "statistical isotropy." That is, the CMB
fluctliations neither align with any preexisting preferred
directions (for example, the earth's axis) nor themselves
collectively define a preferred direction.

Inflation further predicts that the amplitude of each of the
modes (the volume at which each instrument is playing, if we
think about an orchestra) is random, from among a range of
possibilities. In particular, the distribution of probabilities
follows the shape of a bell curve, known as a Gaussian. The most
likely amplitude, the peak of the curve, is at zero, but in
general nonzero values occur, with decreasing probability the
more the amplitude deviates from zero. Each mode has its own
Gaussian curve, and the width of its Gaussian distribution (the
wider the base of the "bell") determines how much power (how much
sound) is in that mode.

Inflation tells us that the amplitudes of all the modes should
have Gaussian distributions of very nearly the same width. This
property comes about because inflation, by stretching the
universe exponentially, erases, like a pervasive cosmic iron, all
traces of any characteristic scales. The resulting power spectrum
is called flat because of its lack of distinguishing features.
Significant deviations from flatness should occur only in those
modes produced at either the end or the beginning of inflation.

Missing Notes

S P H E R I C A L H A R M 0 N i c s represent progressively more
complicated ways that a sphere can vibrate in and out. As we look
closer at the harmonics, we begin to see where the observations
run into troubling conflicts with the model. These modes are
convenient to use, because all our information about the distant
universe is projected onto a single spherethe sky. The lowest
note (labeled 1=0) is the monopole - the entire sphere pulses as
one. The monopole of the CMB is its average temperature-just 2.7
25 degrees above absolute zero [see box on page 411.

The next lowest note (labeled l=1) is the dipole, in which the
temperature goes up in one hemisphere and down in the other. The
dipole is dominated by the Doppler shift of the solar system's
motion relative to the CMB; the sky appears slightly hotter in
the direction the sun is traveling.

In general, the oscillation for each value of 1 (0, 1, 2 ... ) is
called a multipole. Any map drawn on a sphere, whether it be the
CM11's temperature or the topography of the earth, can be broken
down into multipoles. The lowest multipoles are the largest-area,
continent- and ocean-size undulations on our temperature map.
Higher multipoles are like successively smaller-area plateaus,
mountains and hills (and trenches and valleys) inserted in
orderly patterns on top of the larger features. The entire
complic ated topography is the sum of the individual multipoles.

For the CMB, each multipole 1 has a total intensity, Clroughly
speaking, the average heights and depths of the mountains and
valleys corresponding to that multipole, or the average volume of
that instrument in the orchestra. The collection of intensities
for all different values of 1 is called the angular power
spectrum, which cosmologists plot as a graph.

The graph begins at C2 because the real information about cosmic
fluctuations begins with 1=2. The illustration on page 42 shows
both the measured angular power spectrum from WMAP and the
prediction from the inflationary lambda cold dark matter model
that most closely matches all the measurements. The measured
intensities of the two lowest-1 multipoles, C2 and C3, the
so-called quadrupole and octopole, are considerably lower than
the predictions. The COBE team first noticed this deficiency in
the low-1 powe r, and WMAP recently confirmed the finding. In
terms of topography, the largest continents and oceans are
mysteriously low and shallow. In terms of music, we are missing
bass and tuba.

The effect is even more dramatic if instead of looking at the
total intensities (the Cl's) one looks at the so-called angular
correlation function, C(theta). To understand this function,
imagine we look at two points in the sky separated by an angle 0
and examine whether they are both hotter (or both colder) than
average, or one is hotter and one colder. C(theta) measures the
extent to which the two points are correlated in their
temperature fluctuations, averaged over all the points in the
sky. Experimenta lly we find that the C (0) for our universe is
nearly zero at angles greater than about 60 degrees, which means
that the fluctuations in directions separated by more than about
60 degrees are completely uncorrelated. This result is another
sign that the low notes of the universe that inflation promised
are missing.

This lack of large-angle correlations was first revealed by COBE,
and WMAP has now confirmed it. The smallness of C (0) at large
angles means not only that C2 and C3 are small but that the ratio
of the values of the first few total intensities-up to at least
C4-are also unusual. The absence of large-angle power is in
striking disagreement with all generic inflationary models.

This mystery has three potential solutions. First, the unusual
results may be just a meaningless statistical fluke. In
particular, uncertainties in the data may be larger than have
been estimated, which would make the observed results less
improbable. Second, the correlations may be an observational
artifact-an unexpected physical effect that has not been
compensated for in the WMAP team's analysis of its data. Finally,
they may indicate a deeper problem with the theory.

Several authors have championed the first option. George
Efstathiou of the University of Cambridge was first, in 2003, to
raise questions about the statistical methods used to extract the
quadrupole strength and its uncertainty, and he claimed that the
data implied a much larger uncertainty. Since then, many others
have looked at the methods by which the WMAP team extracted the
low-1 Cl and concluded that uncertainties caused by the emissions
of our own Milky Way galaxy are larger than what researchers orig
inally inferred.

Mysterious Alignments

TO ASSESS THESE DOUBTS about the significance of the discrepancy,
several groups have looked beyond the information contained in
the Cl's, which represent the total intensity of a mode. In
addition to Cl, each multipole holds directional information. The
dipole, for instance, has the direction of the hottest half of
the sky. Higher multipoles have even more directional
information. If the intensity discrepancy is indeed just a fluke,
then the directional information from the same

The absence of large-angle power is in striking disagreement with
most inflationary theories.

data would be expected to show the correct generic behavior. That
does not happen, however.

The first odd result came in 2003, when Angelica de
Oliveira-Costa, Max Tegmark, both then at the University of
Pennsylvania, Matias Zaldarriaga of Harvard University and Andrew
Hamilton of the University of Colorado at Boulder noticed that
the preferred axes of the quadrupole modes, on the one hand, and
of the octopole modes, on the other, were remarkably closely
aligned. These modes are the same ones that seemed to be
deficient in power. The generic inflationary model predicts that
each of these modes sho uld be completely independent-one would
not expect any alignments.

Also in 2003 Hans Kristian Eriksen of the University of Oslo and
his co-workers presented more results that hinted at alignments.
They divided the sky into all possible pairs of hemispheres and
looked at the relative intensity of the fluctuations on the
opposite halves of the sky. What they found contradicted the
standard inflationary cosmology-the hemispheres often had very
different amounts of power. But what was most surprising was that
the pair of hemispheres that were the most different were the
ones l ying above and below the ecliptic, the plane of the
earth's orbit around the sun. This result was the first sign that
the CMB fluctuations, which were supposed to be cosmological in
origin, with some contamination by emission in our own galaxy,
have a solar system signal in them-that is, a type of
observational artifact.

Meanwhile one of us (Starkman), together with Craig Copi and
Dragan Huterer, then both at Case Western Reserve University, had
developed a new way to represent the CMB fluctuations in terms of
vectors (a mathematical term for arrows). This alternative
allowed us (Schwarz, Starkman, Copi and Huterer) to test the
expectation that the fluctuations in the CMB will not single out
special directions in the universe. In addition to confirming the
results of de Oliveira-Costa and company, we revealed some
unexpecte d correlations in 2004. Several of the vectors lie
surprisingly close to the ecliptic plane. Within that plane, they
sit unexpectedly close to the equinoxes-the two points on the sky
where the projection of the earth's equator onto the sky crosses
the ecliptic. These same vectors also happen to be suspiciously
close to the direction of the sun's motion through the universe.
Another vector lies very near the plane defined by the local
supercluster of galaxies, termed the supergalactic plane.

Each of these correlations has less than a one in 300 chance of
happening by accident, even using conservative statistical
estimates. Although they are not completely independent of one
another, their combined chance probability is certainly less than
one in 10,000, and that reckoning does not include all the odd
properties of the low multipoles.

Some researchers have expressed concern that all these results
have been derived from maps of the full CMB sky. Using the
full-sky map might seem like an advantage, but in a band around
the sky centered on our own galaxy the reported CMB temperatures
may be unreliable. To infer the CMB temperature in this galactic
band, one must first strip away the contributions of the galaxy.
Perhaps the techniques that the WMAP team or other groups have
used to remove the galactic thumbprints are not reliable enough.
Ind eed, the WMAP team cautions other researchers against using
its full-sky map; for its own analysis, it uses only those parts
of the sky outside the galaxy. When Uros SeIjak of Princeton
University and Anze Slosar' of the University of LjubIjana
excluded the galactic band, they found that the statistical
significance of some of these alignments declined at some
wavelengths. Yet they also found that the correlations increased
at other wavelengths. Our own follow-up work suggests that the
effects of the ga laxy cannot explain the observed correlations.
Indeed, it would be very surprising if a misunderstanding of the
galaxy caused the CMB to be aligned with the solar system.

The case for these connections between the microwave background
and the solar system being real is strengthened when we look more
closely at the angular power spectrum. Aside from the lack of
power at low l, there are three other points-l=22, l=40 and l=210
- at which the observed power spectrum differs significantly from
the spectrum predicted by the best-fit lambda cold dark matter
model. Whereas this set of differences has been widely noticed,
what has escaped most cosmologists' attention is that these t
hree deviations are correlated with the ecliptic, too.

Two explanations stand out as the most likely for the correlation
between the low-l CMB signal and features of the solar system.
The first is an error in the construction or understanding of the
WMAP instruments or in the analysis of the WMAP data (so-called
systematics). Yet the WMAP team has been exceedingly careful and
has done numerous crosschecks of its instruments and its analysis
procedure. It is difficult to see how spurious correlations could
accidentally be introduced. Moreover, we have found simi lar
correlations in the map produced by the COBE satellite, which
used different instruments and analysis and so would have had
mostly independent systematics.

The results could send us back to the drawing board about the
earig universe.

A more probable explanation is that an unexpected source or
absorber of microwave photons is contaminating the data. This new
source should somehow be associated with the solar system.
Perhaps it is some unknown cloud of dust on the outskirts of our
solar system. But this explanation is itself not without
problems: How does one get a solar system source to glow at
approximately the wavelength of the CMB brightly enough to be
seen by CMB instruments, or to absorb at CMB wavelengths, yet
remain sufficiently i nvisible in all other wavelengths not to
have yet been discovered? We hope we will be able eventually to
study such a foreground source well enough to decontaminate the
CMB data.

Back to the Drawing Board?

At first glance, the discovery of a solar system contaminant in
the CMB data might appear to solve the conundrum of weak
large-scale fluctuations. Actually, however, it makes the problem
even worse. When we remove the part that comes from the
hypothetical foreground, the remaining cosmological contribution
is likely to be even smaller than previously believed. (Any other
conclusion would require an accidental cancellation between the
cosmic contribution and our supposed foreground source.) It would
then be harder to claim that the absence of low 1 power is just a
statistical accident. It looks like inflation is getting into a
major jam.

A statistically robust conclusion that less power than expected
exists on large scales could send us back to the drawing board
about the early universe. The current alternatives to generic
inflation are not terribly attractive: a carefully designed
inflationary model could produce a glitch in the power spectrum
at just the right scale to give us the observed absence of
large-scale power, but this "designer inflation" stretches the
limits of what we look for in a compelling scientific theory - an
exercise ak in to Ptotemy's addition of hypothetical epicycles to
the orbits of heavenly bodies so that they would conform to an
Earth-centered cosmology.

One possibility is that the universe has an unexpectedly complex
cosmic topology [see "Is Space Finite?" by jean-Pierre Luminet,
Glenn D. Starkman and jeffrey R. Weeks; SCIENTIFIC AMERICAN,
April 1999). If the universe is finite and wrapped around itself
in interesting ways, like a doughnut or pretzel, then the
vibrational modes it allows will be modified in very distinctive
ways. We might be able to hear the shape of the universe, much as
one can hear the difference between, say, church bells and wind
chim es. For this purpose, the lowest notes-the largest-scale
fluctuations- are the ones that would most clearly echo the shape
(and the size) of the universe. The universe could have an
interesting topology but have been inflated precisely enough to
take that topology just over the horizon, making it not just hard
to see but very difficult to test.

Is there hope to resolve these questions? Yes, we expect more
data from the WMAP satellite, not only on the temperature
fluctuations of the sky but also on the polarization of the
received light, which may help reveal foreground sources. In 2007
the European Space Agency will launch the Planck mission, which
will measure the CMB at more frequency bands and at higher
angular resolution than WMAP did. The higher angular resolution
is not expected to help solve the low-1 puzzle, but observing the
sky in many m ore microwave Iccolors" will give us much better
control over systematics and foregrounds. Cosmological research
continues to bring surprises-stay tuned.

On 24 Jul 2005 03:31:09 -0700, "Cos_mo" wrote:


What do you think of the following?

Is the Universe Out of Tune? by Glenn D. Starman, Dominik J.
Schwarz Scientific American August 2005

[Snip...]

1. That puting this here might well be a copyright violation
of Sci-Am copyright.

2. No surprise to me, we've (myself & Mingst) have predicted
these effects for years now. Namely, the CMB is background
noise of the space-time continuum NOT the reminants of any
cosmic fireball. No inflation, and most certainly a local
component of it due to the local region, including the matter
in the instrumentation. We've begged experimentalist to test
a CMB detection in an cyrogenic cooled isolation chamber
(liquid He @ 0.5 °K) to look for the predicted local signal.

I for one, feel vindicated.

Paul Stowe

Based on this article, I have two questions for a physics class to answer that I am unsure of.

1. Explain what is meant by a mode of vibration. Include a diagram to help with your explanation. What does "l" represent (a lower case "L")?

2. What is the disadvantage of observing a "full CMB sky"? In order for these observations to be useful, what must be done?

3. What are the possible conclusions for the observations described in the article?

Any help that anyone can provide would be beyond amazing. Thank you so much!

"physicshelp" wrote in message
news

Based on this article, I have two questions for a physics class to
answer that I am unsure of.

1. Explain what is meant by a mode of vibration. Include a diagram
to help with your explanation. What does "l" represent (a lower case
"L")?

2. What is the disadvantage of observing a "full CMB sky"? In order
for these observations to be useful, what must be done?

This should answer the first two:

http://www.astro.ucla.edu/~wright/CMB-DT.html

3. What are the possible conclusions for the observations described in
the article?

Observations don't always lead to conclusions. We
have seen unusual values but we don't have a model
that predicts them so further study and measurements
are the way forward.

George