In my
previous post I discussed cosmic habitability categories, which
involve four possible types of universes: uninhabitable universes (in
which life can't exist), barely habitable universes (in which it is
very hard but just barely possible for intelligent life to exist),
moderately habitable universes (offering more favorable conditions),
and abundantly habitable universes (in which life might be able to
evolve all over the universe, with many planets having life all over
them, and intelligent life having great prospects for being able to
survive for eons). It seems that our universe is the fourth type of
universe, as it does not have any serious shortfall in regard to
habitability.
Now
let us consider two interesting questions: (1) which of these types
of universes are the most likely and the second-most-likely to exist? (2)
what type of prediction about the habitability of the universe is
implied by scientific materialism?
In my
previous post I described a group of habitability necessities
that are required for any universe to be habitable, and I also listed
a series of factors I called habitability boosters, each of
which would increase the habitability of a universe (without being an
absolutely necessary precondition for the habitability of a
universe). I then used these factors to define the different
habitability categories:
Uninhabitable
universe: A universe in which intelligent life cannot evolve
anywhere, because it is missing one or more of the habitability
necessities.
Barely
habitable universe: A universe that has all of the habitability
necessities, but none or only one or two of the habitability
boosters.
Moderately
habitable universe: A universe that has all of the habitability
necessities, and roughly half of the habitability boosters.
Abundantly
habitable universe: A universe that has all of the habitability
necessities, and all or almost all of the habitability boosters.
So to
delve into the relative likelihood of these types of universes, we
must consider first : what is the chance of the habitability
necessities occurring? Then we can consider what is the chance of the
habitability boosters occurring.
Why a Random Universe
is Overwhelmingly Likely To Be Uninhabitable
The
first habitability necessity I mentioned was stable atoms heavier
than hydrogen. We take heavy elements such as carbon and oxygen for
granted, but we shouldn't. We should not expect them to exist in more
than a very tiny fraction of all random universes. You wouldn't have
atoms other than hydrogen unless you have the strange convenience we
call the strong nuclear force, which binds together nuclei together,
overcoming the electromagnetic repulsion between protons. First such
a force must exist. Second, it must have the right strength level
(and it is actually the strongest known force). You must also have
electromagnetism causing a force of attraction between protons and
electrons, which keeps electrons in an atom. Then you need quantum
mechanical laws that prevent such attraction from causing electrons
to fall into the nucleus. Given all of the ways you can wrong, it
seems the chance of atoms existing in a universe of random constants
and forces is very low.
The
second habitability necessity I mentioned was planets with a
reasonable level of gravity. To meet this necessity a universe needs
a universal force of gravitation that is attractive. The very
existence of such a force would seem to be no more than a
one-in-three likelihood, since we can imagine two other equally likely
possibilities (a universe with no such force at all, and a universe
with a force of repulsion between all particles). But the likelihood
of habitable planets in a random universe is actually much, much
smaller than that. For one thing, the strength level of gravitation
(signified in our universe by the gravitational constant) must be
within a quite narrow range of values. If gravitation is too weak,
planets won't hold together. If gravitation is too large, then the
gravity on all planets will so great that no animals will be able to
move around on a planet (and there are also reasons why an expanding
universe would have collapsed into black holes if gravitation had
been much higher). There is also fine-tuning required in regard to
the proton charge and the electron charge. For example, in our
universe if the proton charge and the electron charge were not
exactly the same, gravitation would not be enough to hold planets
together (since the electromagnetic force is roughly a trillion
trillion trillion times stronger than the gravitational force, even a
relatively tiny difference in the proton charge and the electron
charge would cause repulsive effects exceeding the attractive effects
of gravitation in large bodies such as planets, preventing their existence, as mentioned by Greenstein here).
In
short, while we take planets for granted (having lived on one all our
lives), it seems that we should expect only a tiny fraction of random
universes to have planets suitable for the existence of mobile living
creatures
The
likelihood of a random universe being habitable seems even smaller
when we consider the third habitability necessity I mentioned, the
necessity of having a relatively empty vacuum. The issue (discussed here) is
that according to quantum mechanics, quantum fluctuations should
cause the vacuum to be teeming with energy. This is the “vacuum
catastrophe” problem or cosmological constant problem that is
perhaps the biggest unsolved problem in physics. According to the
predictions of quantum field theory, we should live in a vacuum that
is at least 1060
times denser than the observed vacuum – so dense that a square
meter of the vacuum should be denser than a square meter of steel.
Pretty much the only idea physicists have as to why our vacuum is so
relatively empty is that there was some fantastically improbable and
coincidental “cancellation of contributions” leaving us with a
nearly empty vacuum – something rather like the annual savings of
Chinese citizens coincidentally matching the annual credit card
charges of US citizens, with an exact match to the penny. The chance
of such a thing in a random universes is very, very low.
The
likelihood of a random universe being habitable seems even smaller
when we consider the fourth habitability necessity I mentioned, the
necessity of having both carbon and oxygen in the universe.
Scientists have discussed how if the strong nuclear force had been
slightly weaker or slightly stronger, we would have been left with a
universe that would have had either lots of carbon but no oxygen, or
lots of oxygen but no carbon. Apparently getting both required a lot
of luck that would be very unlikely in most random universes.
Based
on these considerations (which do not at all discuss all of the
habitability necessities of a habitable universe), we can conclude
that uninhabitable universes are vastly more likely than habitable
universes. Such a conclusion has been made by quite a few previous
scientists. A recent article by physicist Luke Barnes has a relevant
graph showing habitable universes as just a small portion of a
parameter space that is much bigger (and there are lots of bulls-eyes that nature must hit for a universe to be habitable, not just the one illustrated here).
Why a Barely Habitable
Universe Should Be Vastly More Likely Than a Moderately Habitable
Universe Or an Abundantly Habitable Universe
The
conclusion above has been made by many writers, but now let's look at
a question rarely considered, but quite important: in the class of
all habitable universes, what fraction should be we expect to be just
barely habitable? In other words, should we expect that barely
habitable universes are vastly more common than moderately habitable
universes and abundantly habitable universes?
I
will now argue that we should expect exactly that, mainly because the habitability boosters that I identified are unlikely to occur in
random universes. Let's look at the first habitability booster I
identified, the existence of radiant stars.
The
likelihood of you getting radiant stars in a random universe is
discussed in section 4.7 of the scientific paper here. The paper
quotes a scientific paper by Adams mentioning a 1 in 4 chance of
stars being possible if you allow the fine-structure constant and the
gravitational constant to have values differing from their current
values by ten times. But this is an example of “putting the camera
near the needle hole in order to make the needle hole look big.”
There's no reason why the the fine-structure constant and the
gravitational constant could not have values a million times smaller
or larger. When we properly consider that, we are then left with a
probability of less than 1 in a million that a random universe would
have radiant stars. See
here for more on this issue. On page 40 of this paper, physicist
Luke Barnes says, “We conclude that the existence of stable stars
is indeed a fine-tuned property of our universe” – in other
words, something that would be very unlikely to occur in a random
universe.
Another
habitability booster I mentioned is the existence of sun-like stars.
A universe that has such stars will tend to be a lot more habitable
than one merely having red stars (planets around red stars are
predicted to be tidal-locked planets on which there is only a ring of
habitability between the side facing the star and the opposite side).
It turns out that the fine-tuning for sun-like stars is far greater
than the fine-tuning needing for red stars. Below is a quote from
page 73 of The Accidental Universe by physicist Paul Davies:
If
gravity were very
slightly weaker, or electromagnetism very
slightly stronger, (or the electron slightly less massive relative to
the proton), all stars would be red dwarfs. A correspondingly tiny
change the other way, and they would all be blue giants.
It
seems, therefore, that in random universes we are extremely unlikely
to see sun-like stars, and that the requirements for such stars are
much more special (much greater “long shots”) than the
requirements for stars in general, just as the requirements for
getting into Harvard are much harder-to-meet than the requirements
for getting into “some type of college.”
Another
habitability booster I mentioned is the existence of large amounts of
both carbon and oxygen. Scientists have identified this as something
that would not occur unless fundamental constants are fine-tuned.
According to page 41 of this paper, a 1 part in 100,000 change in one fundamental
constant would change things so that the main stellar process
producing carbon and oxygen would produce either carbon or oxygen,
but not both. That paper concludes, “The ability of stars in our
universe to produce both carbon and oxygen seems to be a rare
talent.” So we can conclude that this habitability booster (an
abundance of both carbon and oxygen) is highly improbable in a random
universe.
Another
habitability booster I mentioned is low radioactivity. For simplicity
let's just assume there is maybe 1 chance in 2 of such a condition.
It would seem to be many times harder for a universe to have the last
habitability booster I mentioned, that of low static electricity (so
there are not all kinds of lethal static electricity amounts hanging
around all over the place, ready to kill anyone who touches them).
Low static electricity seems to require two different coincidences:
the coincidence that the number of protons in a universe roughly
equals the number of electrons (as it seems to do in our universe),
and the coincidence that the proton charge equals the electron charge
(as it does in our universe, to twenty decimal places). If you change
those conditions just a little, you will be left with a universe in
which there is so much free-floating static electricity (excess
charges floating about) that life should be very rare, very
short-lived or both (imagine a planet teeming with billions of
“static electricity landmines” and you'll get the idea).
So
speaking very generally, not only are the habitability necessities
rare strokes of luck that should be very unlikely to occur in a random
universe, but also the habitability boosters are almost
all rare strokes of luck that should be very unlikely to occur in
a random universe. Consequently, barely habitable universes should be
vastly more likely than moderately habitable universes or abundantly
habitable universes. Barely habitable universes should be much more
likely because they require much fewer “improbable strokes of
luck” than moderately habitable and abundantly habitable universes.
The
visual below illustrates this idea. This is a very schematic visual,
and its proportions are not supposed to represent the actual ratio
between different habitability categories. The visual refers merely to probabilities, not actualities. In the first bar we see
something that represents very roughly a ratio between uninhabitable
universes and habitable universes (although the actual fraction of
habitable universes should be much smaller). The second bar is a
closeup of the right edge of the first bar. When we zoom in and look
at the habitable universes, we find that almost all of them are
barely habitable universes, with a few (on the right side) being
moderately habitable. The third bar is a closeup of the right edge
of the second bar. When we zoom in and look at the universes that are
better than barely habitable, we find that almost all of them are
moderately habitable and only a tiny fraction are abundantly
habitable. Although this visual is highly schematic, I think it gives
a rough idea of the relative probabilities of a random universe being
uninhabitable, barely habitable, moderately habitable or abundantly
habitable.
What Prediction Does
Scientific Materialism Make About Our Universe's Habitability?
Now
let us consider: what type of prediction does scientific materialism
make about the habitability of our universe? The answer is: it makes
a prediction that could not be more wrong.
The
actual prediction that scientific materialism makes about the
habitability of universe is that our universe should be about the most
uninhabitable universe imaginable. This is because of the
long-standing problem in physics known as the cosmological constant
problem or the vacuum catastrophe problem. Because of weird quantum
mechanical considerations, physics predicts the vacuum of space
should be seething with a very dense sea of virtual particles,
particles that should cause each cubic meter of space to have more
mass-energy than solid steel. Under such conditions, no type of life
could exist for even an instant – it would be easier for life to
exist in the middle of the sun.
So
what we get from scientific materialism is the prediction that the
universe should be as uninhabitable as anything we can imagine. But
suppose we grant a special favor, and simply ignore the predictions
of quantum mechanics. Suppose we pay no attention to the whole
cosmological constant problem and vacuum catastrophe issue that
physicists have been puzzled by for forty years. What type of
universe does scientific materialism then predict? It then still
predicts that our universe should be an uninhabitable universe. This is
simply because an uninhabitable universe should be trillions of times
more likely than any type of habitable universe. That's because of all the extremely improbable long shots and coincidences for a
universe to meet the habitability necessities I have mentioned (and
others I haven't mentioned).
But
what if we grant a second special favor, and assume that
observers must exist in a universe, perhaps by using some kind of
dubious “selection effect” reasoning or “anthropic principle”
reasoning. There is no sound basis for granting such a favor, but
suppose we grant it anyway. What then does scientific materialism
predict? It then predicts that our universe should only be a barely
habitable universe. Why? Because, as we have seen, barely habitable
universes should be vastly more likely than abundantly habitable
universes like the one we live in. The list of long shots and
coincidences that must be met in order to have a barely habitable
universe is much shorter than the list of long shots and coincidences
that must be met for moderately habitable universes or abundantly
habitable universes.
So
even if we grant two special favors, scientific materialism still
makes the wrong prediction about what type of universe our universe
should be. But what if we throw in a multiverse – the assumption
that there are many universes? Does that help? No, it doesn't help at
all. The habitability predictions of scientific materialism regarding
our universe are not changed at all if we assume that there are many
universes. It is a basic fact of probability math (ignored by
multiverse enthusiasts) that you do not increase the chance of
success on any one random trial by increasing the number of random
trials.
The
predictive failure of scientific materialism in this regard is very
spectacular. It's a predictive failure far worse than has ever been
made by any errant gypsy fortune teller or any misguided apocalyptic
preacher. A failure this spectacular is a sure sign of underlying
false assumptions. What we need is a worldview that predicts that our
universe should be a type of universe like the type that it is, an abundantly habitable universe.
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