Around about 1978,
cosmologists (the scientists who study the universe as a whole) were
puzzled by a problem of fine-tuning. They had figured out that the
expansion rate of the very early universe (at the time of the Big
Bang) must have been incredibly fine-tuned, apparently to one part in
ten to the sixtieth power. This dilemma was known as the flatness
problem.
Around
then Alan Guth (an MIT professor) proposed a way to solve the
flatness problem. Guth proposed that for a tiny fraction of its first
second (for less than a trillionth of a trillionth of a second), the
universe expanded at an exponential rate. The universe is not
expanding at any such rate, but Guth proposed that after a very brief
instant of exponential expansion, the universe switched back to the
normal, linear expansion that it now has.
Even
though there was no evidence for it, and the idea was very
far-fetched from the beginning, Guth's idea became very popular among
the small tribe of cosmologists. We can call this idea Guthism, and
we can call the small tribe of cosmologists who adopted it Guthists.
Guthism can also be called the cosmic inflation theory, although
Guthism may be better term, to avoid confusion with the broader
concept of the expansion of the universe (which does not require the
idea of primordial cosmic inflation).
In
January of 2017 Scientific American published an article attacking
Guthism. The article was written by Princeton professor Paul
Steinhardt and Harvard professor Abraham Loeb, along with Anna Iijas.
The trio methodically dismantled the Guthist idea of primordial
cosmic inflation.
Commenting
on a Planck satellite data release that was proclaimed as being in
support of Guthism, the article states, “If anything, the
Planck data disfavored the simplest inflation models and exacerbated
long-standing foundational problems with the theory, providing new
reasons to consider competing ideas about the origin and evolution of
the universe.”
Here
is a quote from the paper:
Two
improbable criteria have to be satisfied for inflation to start.
First, shortly after
the big bang, there has to be a patch of space where the quantum
fluctuations of spacetime have died down and the space is well
described by Einstein’s classical equations of general relativity;
second, the patch of space must be flat enough and
have a smooth enough distribution of energy that the inflationary
energy can grow to dominate all other forms of energy. Several
theoretical estimates of the probability of finding a patch with
these characteristics just after the big bang suggest that
it is more difficult than finding a snowy mountain equipped with a
ski lift and well-maintained ski slopes in the middle of a desert.
A
stunning statement – that a theory paraded around as a standard of
cosmology is really more implausible than “finding a snowy mountain
equipped with a ski lift and well-maintained ski slopes in the middle
of a desert.”
The
paper then goes on to explain why Guthism is basically worthless in
terms of helping to explain the flatness problem. The authors state
this:
More
important, if it were easy to find a patch emerging from the big bang
that is flat and smooth enough to start inflation, then inflation
would not be needed in the first place. Recall that the entire
motivation for introducing it was to explain how the visible universe
came to have these properties; if starting inflation requires those
same properties, with the only difference being that a smaller patch
of space is needed, that is hardly progress.
The
scientists also tell us, “Not only does inflation require starting
conditions that are difficult to obtain, it also impossible to stop
inflation once it gets going.” They are referring to the “graceful
exit” problem. Appealing to an “inflaton field” that has never
been discovered, Guthism tells the tale that exponential cosmic
inflation lasted for less than a trillionth of a second, and that it
both started and stopped during the universe's first second. But
getting the stopping to occur requires fine-tuning and vastly
improbable circumstances similar to the fine-tuning and vastly improbable
circumstances needed to get this exponential cosmic inflation
beginning in the first place. It's like trying to explain an
elephant appearing out of nowhere and then disappearing in less than
a second.
The
three scientists suggest a “bouncing universe” theory as an
alternative to Guthism, but there are powerful reasons (discussed
here) for rejecting such a theory. Our three scientists have done a
fine job at showing the low credibility of Guthism, but have not
succeeded in presenting some viable alternative. But that's okay,
because we can simply say that we do not understand the universe's
beginning, rather than pretending to understand primordial mysteries
beyond our comprehension and knowledge. Kudos to anyone who shows
the weaknesses of a prevailing theory, even if they don't succeed in presenting a viable replacement for such a theory.
What
do you call a theory that tells a “once upon a time” story
describing unproven and unbelievable narrative details of the
universe's first second – a theory hanging around because it has
become a verbal story tradition of a little clique of scientists?
The best term I can think of is: tribal folklore.
Darwinists
have constantly been telling us, “Nature does not make leaps.”
But the cosmic inflation theorists want you to believe that nature
made two gigantic leaps in its first second. According to them, the
first of the leaps when was this exponential period of cosmic
inflation started; and the second leap, a fraction of a second later,
was when this exponential period of cosmic inflation ended (with the
universe returning to the normal, linear expansion rate we now
observe).
Is
there any chance that this folk tale will ever be verified? No,
because we can never hope to look back to the beginning and see what
happened. The cosmic density preceding the “recombination era” scattered photons from the
very beginning of the Big Bang, and prevents us from looking back to a
time earlier than about 380,000 years after the Big Bang.
If
you do a Google search for “cosmic inflation,” you will find
quite a few web links proclaiming that observations have confirmed
the theory. No such thing has happened. The web links date from 2014,
when the BICEP2 team announced observations which it claimed found
something (primordial b-modes) that the cosmic inflation theory had
predicted. But later in the year, a consensus emerged that the team
had done no such thing, and that the observations were just as
likely to have been the result of ordinary dust. This was all a
great big embarrassment to modern cosmology, since a giant false
alarm had been raised. At a time in the spring of 2014 when most major scientific web sites were toasting the supposed glorious success of
BICEP2, this blog was one of only a handful of web sites raising
doubts about the claim (my 2014 posts on the topic are here). By the end of the year, things had reversed,
and the scientific world was pretty much saying this about BICEP2:
“Never mind.”
The
Scientific American article by the three scientists has provoked an
unusual response. The main supporters of Guthism (including Alan Guth
and Andrei Linde) along with about 30 other cosmologists have
published a rebuttal article called “A Cosmic Controversy.” It is
kind of an authoritarian power play, designed to impress the reader
by listing authorship by some of the top names in cosmology. The
list of authors is very impressive, but the reasoning of the rebuttal
is very unimpressive.
The
core of the rebuttal is the claim that cosmic inflation theory
(Guthism) has made several predictions that have proven true. The
predictions listed are that the universe is geometrically flat, that
ripples in the cosmic background radiation should be nearly “scale
invariant,” that these ripples should be “adiabatic,” and that
these ripples should be “Gaussian.”
Let
me explain why such things cannot be cited as good evidence that
Guthism is correct. First, we must recognize that many a false
theory may make a true prediction. Some person may have a false
theory that the Freemasons are secretly plotting to take over the
world. That theory may predict (among other things) that interest
rates will rise, that the stock market will go down, and that real
estate prices will not change much. If it then happens that each of
these three things happens, it does nothing to prove that such a
theory of a Freemason conspiracy is correct. There would be about 1
chance in 10 of such predictions being right accidentally, and a 1 in
10 coincidence is not an impressive one.
In
physics the theories of gravitation, electromagnetism, and quantum
mechanics are regarded very highly because they make very precise
predictions that turn out to be exactly correct. For example, a
theory of gravitation may predict that a particular small asteroid
will crash into the moon at exactly 10:35 PM EST on January 23, 2025.
When such exact predictions turn out to be precisely true, it is
very impressive, because it's hard to see how the theory could be so
precisely right if it were not true. If the theory were not true,
such a prediction would seem to require perhaps a 1 in a billion
coincidence.
Conversely,
there is nothing impressive about a theory being correct with a few
predictions that may be coincidentally correct with a likelihood of
about 1 in 2 or 1 in 3. The
overall unlikelihood of such a level success is only about 1 in 6 or
1 in 9, which is not very unlikely at all.
In
the case of the predictions of Guthism (primordial cosmic inflation),
the items mentioned by the “A Cosmic Controversy” rebuttal are
items that would have not been very unlikely for a false theory to
have predicted. There are three possible geometries of space (flat,
open, and closed), so you have 1 chance in 3 of being right if you
pick one of those. If you guess that primordial ripples were
Gaussian, you have about 1 chance in 2 of being correct. If you guess
that primordial ripples were scale-invariant, you also have 1 chance
in 2 of being correct. If you guess that fluctuations were adiabatic,
you also have about 1 chance in 2 of being correct.
We
may also note the fact that over the past 35 years there have been
many hundreds of papers published presenting different versions of
Guthist cosmic inflation theories. The predictions of these models
have been “all over the map.” Typically a particular version of
the theory will present a model consisting of equations, with lots of
free parameters that can be plugged into the equations. A particular
model (one version of the cosmic inflation theory) may predict a
million different things, depending on what is chosen for the free
parameters. And hundreds of such Guthist models have been published,
each with slightly different equations.
So
even the meager predictive successes mentioned in the “A Cosmic
Controversy” rebuttal are not at all something that can be trotted
out as some sign that “the predictions of cosmic inflation theory
have been verified.” The few predictions mentioned are predictions
cherry picked from a large family of models, which made predictions
all over the map.
If
I advanced some economic theory, and got disciples to grind out
hundreds of different flavors of my theory, I would no doubt be able
to find among some of these works some successful predictions that each had a
chance probability of maybe 1 in 2 or 1 in 3 of being correct. But
that would not be evidence that my theory was correct. Similarly, a
few successful predictions (none very numerically exact) among the
huge number of Guthist cosmic inflation models is not at all impressive,
and something we might well expect to occur by chance.
The
“successful predictions” cited in the “A Cosmic Controversy”
rebuttal are also things that have been produced as the evidence was
gradually coming in. It's not too hard to get successful predictions
if you are predicting as the evidence is coming in. For example, if
it's 2007 and the evidence is starting to come in that the housing
market is collapsing, it's not hard to predict in that year that the
housing market will collapse.
As
Steinhardt,
Loeb, and Iijas state in their rebuttal to the “Cosmic
Controversy” rebuttal, “Any
inflationary model gives an infinite diversity of outcomes with none
preferred over any other.”
At
this link Steinhardt,
Loeb, and Iijas cite various Guthist cosmic inflation models over
the years which have made false predictions, including some models
predicting an open universe, some models predicting non-guassianity,
some models predicting large tilt, some models predicting deviations
from isotropy, some models predicting bumps and wiggles in the
primordial spectrum, and some models that “predict B-modes with
amplitudes that should have been detected by the WMAP and Planck
satellites.”
It would actually be
a gigantic project probably requiring years of work for someone to
analyze whether the predictions of cosmic inflation models have been
mainly successful or mainly unsuccessful. You would have to do
something like put together an incredibly complex computer program
that included thousands of equations that were extracted from more
than 500 cosmic inflation papers published in the past 35 years. You
would then have to vary the input parameters on all of these models,
and see how well the results matched up with a large variety of
cosmological observations. No one has ever done such a thing,
partially because of the runaway complexity of such a project, which
might be thousands of time more difficult than checking the accuracy
of IPCC predictions on global warming.
In short, it is not right to claim that predictive successes show some
likelihood that Guthist cosmic inflation actually occurred. We must
also consider that the Cold Spot in the cosmic background radiation
seems to be inconsistent with what such a theory predicts (as discussed here).
Imagine
a salesman who knocks on your door and tells you he can make your
kitchen look real nice if you spend only a few dollars to do some
simple work. You let him in to do some work, thinking it will be a
simple affair. Imagine the guy starts fiddling with the pipes and
electricity, and then eventually tells you the job is going to cost
you many thousands of dollars. You think to yourself: I never would
have let this guy in if he had told me that at the beginning.
The
tale of Guthism is a similar tale. It was originally pitched as
something pretty simple. So cosmologists welcomed it. As time
progressed, and the simplest versions kept failing, our Guthists
eventually indicated that the theory required a whole multiverse (a
huge collection of universes). The theory never would have been
initially welcomed if this gargantuan requirement had been confessed at the very beginning.
But by the time the multiverse requirements of Guthism had become
apparent, the Guthist thought virus had infected so many cosmologists
that they were reluctant to say, “This thing has got out of hand –
we've been going in the wrong direction.” It's rather like a
husband who takes the wrong turn trying to get from New York City to
Philadelphia. If you point out his mistake the first few miles, he
may turn around. But by the time he's gone a hundred miles down the
wrong road, he may never admit he made a wrong turn. And even if he
starts seeing signs saying, “Welcome to Massachusetts,” he may
still swear he made the right turn.
Postscript: Scientific American columnist John Horgan writes the following:
Almost 40 years after their inception, inflation and string theory are in worse shape than ever. The persistence of these unfalsifiable and hence unscientific theories is an embarrassment that risks damaging science’s reputation at a time when science can ill afford it. Isn’t it time to pull the plug?
Here is a relevant previous post of mine, entitled "Let's Keep the Big Bang but Dump the Cosmic Inflation Theory."
Postscript: Scientific American columnist John Horgan writes the following:
Almost 40 years after their inception, inflation and string theory are in worse shape than ever. The persistence of these unfalsifiable and hence unscientific theories is an embarrassment that risks damaging science’s reputation at a time when science can ill afford it. Isn’t it time to pull the plug?
Here is a relevant previous post of mine, entitled "Let's Keep the Big Bang but Dump the Cosmic Inflation Theory."
ReplyDeleteThere is a way to calculate Hubble's Constant from geometry. The following equation has been tested by a Professor at Imperial College, London, who described it as 'elegant'. It is 2 X a megaparsec X C, divided by Pi to the power of 21. This gives Hubble's Constant as 70.98047 kilometres per second per mega parsec. The value of a parsec for this equation is the standard unit of 3.26 light years. This equation comes from 'The Principle of Astrogeometry' on Kindle Books, which describes how the equation is derived. Deriving the Hubble Constant from geometry involves no measuring differences and errors, and so is the precise value. Scientist do not understand this equation, which is the main problem behind them not agreeing on the true Hubble Constant value. They fumble and guess, create nonsense theories, and it is now plainly seen that the Big Bang idea is not the truth, and the scientists are totally wrong. They can't move forward until they drop their mindsets, and seriously try to understand this simple Hubble Constant equation. They are making a 21st Century blunder, and really don't understand as much (very little) about the universe as they boast to the public!! David Hine.