From the time of the Big Bang nearly
14 billion years ago, the universe has undergone an amazing
evolution. Imagine if you had been there at the beginning, to witness
the hot smooth density, in which supposedly all of our universe was
packed into a microscopic size. If you knew nothing about the
eventual outcome, you would not have been optimistic about what would
have resulted from this explosive event. Your best bet might have
been a mess of disorganized space junk, with no more order than the
debris resulting from a hydrogen bomb explosion.
But almost 14 billion years later, we
have a universe of remarkable order. Matter is organized into
superclusters of galaxies consisting of clusters of galaxies
consisting of galaxies consisting of solar systems. A large fraction
of the galaxies are the particularly beautiful type called spiral
galaxies. Do scientists really have a firm grip on how this
improbable evolution occurred?
Scientists say that the current
structure of the universe evolved from what are called primordial density
fluctuations. They can see tiny fluctuations in the cosmic background
radiation, which is uniform to about 1 part in 100,000. But how did those
fluctuations get there?
Cosmic Background Radiation
The most common explanation is that
the fluctuations began as quantum fluctuations (matter popping into
existence in accordance with Heisenberg's uncertainty principle), and
that these quantum fluctuations were then amplified by a period of
cosmic inflation (exponential expansion) that occurred for a fraction
of a second when the universe was less than a second old.
The difficulties in this explanation
are many. For one thing, no one has ever actually observed a quantum
fluctuation that caused matter to appear out of nowhere, not even a
fluctuation big enough to produce an atom. Secondly, there are
currently serious credibility issues associated with the theory of
cosmic inflation, issues that have been highlighted by Princeton physicist Paul
Steinhardt in this review. Among those issues are what Steinhardt
calls an “unlikeliness” problem, plus the problem of creating an
inflation theory that both begins and ends an inflation phase while
remaining consistent with observations. Cal Tech physicist Sean Carroll says
here, “When perturbations are taken into account, inflation only
occurs in a negligibly small fraction of cosmological histories,”
and then spells that out as a fraction less than 1 in
1.000,000,000,000,000,000,000,000,000. The leading cosmologist Roger
Penrose has described cosmic inflation as a thermalization process,
and has stated, “There is, however, something fundamentally
misconceived about trying to explain the uniformity of the early
universe as resulting from a thermalization process.” He states
that any thermalization process doing anything would have “been
even more special before the thermalization than after” (The
Road to Reality, page 755).
Third, the inflation theory requires a severe
fine-tuning of its model parameters in order to perform the trick of
inflating these quantum perturbations to be the right size. As one
scientist puts it here:
A lumpiness of about 10-5 is essential for life to get a start. But is it easy to
arrange this amount of density contrast? The answer is most decidedly no! The
various parameters governing the inflating universe must be chosen with great
care in order to get the desired result.
arrange this amount of density contrast? The answer is most decidedly no! The
various parameters governing the inflating universe must be chosen with great
care in order to get the desired result.
In short, we do not yet have a good plausible explanation of how these “seeds of structure” appeared. The only explanations are ones that resort to extensive parameter tweaking, rather like in the graphic below.
Explaining the Growth of Structure: More Nebulous Fudge Factors
Scientists have done calculations regarding the formation of galaxies and the preservation of galactic structure, and have come up with the resounding conclusion that the gravity of visible matter is completely insufficient to explain the origin and persistence of galactic structure.
Consequently cosmologists have come up with some “fudge factors” to help explain things. The two biggest fudge factors are called dark energy and dark matter. Scientists say that dark matter is a mysterious type of matter that is invisible. Dark energy is supposed to be a mysterious unseen energy that pervades all of space. Scientists guess that the universe's mass-energy is 68% dark energy, 27% dark matter, and 5% regular matter.
Total unambiguous observations of dark matter: 0
Total unambiguous observations of dark energy: 0
It's not as if scientists haven't tried. They have spent many dollars and much time with some very fancy observation techniques, but have still come up short. But that hasn't stopped cosmologists from creating a “lambda cold dark matter” theory (called LCDM) designed to explain cosmic structure.
Besides
the fact that it relies on dark matter (the existence of which has
not been verified), there are problems in this LCDM theory. One of
the main problems is that it predicts way too many satellite
galaxies. The paper here describes the problem. According to this link the
LCDM theory predicts that our galaxy should have thousands of
satellite galaxies, but instead it only has about 26.
Another
problem with the LCDM theory is that it predicts that almost all
galaxies should have have large bulges in the center or be spherical.
But between 58% and 74% of disk-shaped galaxies do not have a bulge.
Another problem with the LCDM theory is the difficulty of getting it to produce not just galaxies but a universe with as many beautiful spiral galaxies as we have in our universe.
A spiral galaxy
As this site says, "Cosmological evolution simulations do not generally produce universes
containing large spiral galaxies. Rather they produce clumps of matter
making up roughly spherical amorphous galaxies without anything like the
broad disks and extended arms of a typical spiral galaxy."
In
this story a scientist comments on strange findings he has discovered
by studying deep space:
The limits of our understanding of cosmic structure may also have been highlighted by the recent discovery of the planet HD 106906 b, a planet 11 times the mass of Jupiter. HD 106906 b orbits its star at a distance 650 times the average distance between Earth and the Sun. That puts the planet 20 times farther away from its star than the planet Neptune is from the Sun. This finding seems to be quite incompatible with current theories of solar system formation. HD 106906 b is being called “the planet that shouldn't exist.”
Particle Physics Makes the Situation Even Worse
When we look in the world of particle physics for help with these problems
in explaining large scale structure, we get no help.
The
prevailing theory of large structure formation (the Lambda Cold Dark
Matter theory) is based mainly on the hypothesis of dark matter, but
dark matter is totally unaccounted for in the Standard Model of
physics. Dark matter has no place in that model. That leaves dark
matter as a kind of nebulous “some kind of something.” Do we know
how many dark matter particles there are, or how much mass any dark
matter particle has? We sure don't.
Modern
quantum physics does predict that dark energy should exist. The
problem is that quantum field theory predicts that the dark energy
should be at least 1060 times (a trillion trillion trillion trillion trillion times) larger (and probably 10120 times larger) than the maximum
value that it can be, according to observations. This is known as the
vacuum catastrophe problem or the cosmological constant problem.
Quantum field theory predicts that every cubic meter full of vacuum
should contain more energy than the maximum amount that the
observable universe can contain.
In
light of all these considerations, the graphic below summarizes the
current very shaky state of our current understanding of the
formation of cosmic structure.
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