
Science's Alternative to an Intelligent Creator: the Multiverse Theory - rms
http://discovermagazine.com/2008/dec/10-sciences-alternative-to-an-intelligent-creator
======
sciolizer
Anthropic arguments frustrate me to no end.

1.) "Life as we know it" is an extremely important phrase. Ask a biologist
what life is, and she will probably say something about cells and DNA. It is
possible for other self-replicating combinations of molecules to exist, but
not on Earth, because the Cell/DNA model has become so effective at wiping the
competition out. It's actually really hard to come to a solid definition of
what "life" is, but if you make it sufficiently broad, I suspect you could
find life even in some universes where the fundamental constants differ
significantly from ours.

2.) We have no idea what determines the fundamental constants. You cannot talk
about the "odds" of having a universe like ours until you know the probability
distributions for each of the fundamental constants. Look at the H2O on Earth,
and you will find that a significant portion of it occurs at 0C and 100C. Of
course that is not a coincidence - water often exists at those temperatures
because energy is spent on converting state, not on altering temperature. It's
an equilibrium point. So likewise, it's POSSIBLE that the fundamental
constants (of multiple universes, if they exist) interact in ways that cause
them to arrive at equilibrium points. One really fascinating theory promoting
this idea (and any theory is as good as the next, since we have very little
empirical evidence available to us) is Lee Smolin's argument that the
singularities within blackholes are themselves universe phases. Thus, a kind
of "natural selection" of black holes occurs, which leads to more and more
universes with fundamental constants ideal for producing black holes (and thus
close to the constants necessary for life).

3.) The anthropic principle is just way too convenient, and I fear it de-
motivates scientists from looking deeper into issues that really need
explaining. Roger Penrose argues that there is a surprising lack of parsimony
on behalf of whatever forces (spiritual or natural) brought about our
universe. While our universe appears to have inflated from an initial region
with a phase-space-volume of 10^(10^123), it would have been more than
sufficient to create a life-supporting universe (several! in fact) from a
region with only a phase-space-volume of 10^(10^117). Additionally, Penrose
points out that the odds of creating an exact duplicate of our solar system
from the random coming together of gas and radiation (no Darwinian evolution
necessary!) is only 1 in 10^(10^60). (Penrose calls it "utter chicken feed"
compared to the odds of the Big Bang producing ANY universe of our size). So
even when you invoke the anthropic principle, the question still remains - why
is our (life-supporting) universe so large and so old, when we could have done
with so much less?

~~~
gaius
_The anthropic principle is just way too convenient, and I fear it de-
motivates scientists from looking deeper into issues that really need
explaining._

This I must take issue with. The anthropic principle is what drove the
Renaissance. It's what motivated people like Sir Isaac Newton to better
understand the universe, they believed that this was the way to get closer to
God. The anthropic principle is responsible for the single biggest leap in
science in the history of mankind. Saying "God created it" doesn't excuse
anyone from anything; you still need to work on it, in fact the good Christian
has no excuse not to.

~~~
sciolizer
The anthropic principle did not drive the Renaissance. The scientific
revolution within the Renaissance was driven by a rediscovery of Greek/Arabic
knowledge, the focus on empirical evidence that came with the invention of the
scientific method, and the (yet-to-be-formalized) desire to apply Occam's
razor to every explanation.

The anthropic principle is dual to Creationism. The Creationist says, "It is
because God made it so." The scientist says, "It is because it necessarily
must be so." Neither philosophy, by itself, leads to deeper understanding.

------
Retric
_If gravity were slightly more powerful, the consequences would be nearly as
grave. A beefed-up gravitational force would compress stars more tightly,
making them smaller, hotter, and denser. Rather than surviving for billions of
years, stars would burn through their fuel in a few million years, sputtering
out long before life had a chance to evolve._

This is wrong, with slightly more gravity smaller stars would burn hotter but
there is a wide range of stars that can last for 5 billion years. Now if was
100 times as strong they might have a point but there is about an order of
magnitude to play around with.

~~~
rsheridan6
But would we still be able to get the elements we need for life? We are partly
made of leftovers from supernovas, and so is our sun. It takes more than just
a energy source to create life - you have to have something other than
hydrogen to work with.

~~~
Retric
Assuming everything else was the same and gravity was 5x as strong then a star
around the size of the sun would go super nova in a short time period.
(Granted it would take a lot of time to really model this.)

There is some support for Jupitor producing a little fusion with it's current
mass. If you increase gravity it becomes smaller until it's heat balances out
the force of gravity which increases the amount of fusion taking place.

PS: Less massive stars have a higher surface area to volume ratio. This
reduces their temerature which reduces their fuel usage. But once they run out
of fuel the same type of interesting things are going to happen.

------
robg
The multiverse is my favorite scientific hypothesis. It just seems right. It's
always been cool to think about the boundary conditions of our universe (how
big? how long? how much?). But one among many? That's utterly baffling and
exciting.

Unfortunately, without evidence, it's an argument of faith, like any other.

~~~
trapper
I like the simulation hypothesis. I love how it "explains" some of the
constants we see & quantum physics.

I don't see how belief in "the multiverse" is any different than belief in a
god or the simulation hypothesis. They all have zero evidence and can't be
tested. The obvious question in all three is: what was there before? So they
all have the same problems.

~~~
goodness
The simulation hypothesis actually becomes more likely, though still not
proven, if we get to the point where we can run our own simulated universe.

We might also demonstrate that we were in a simulation if we found an exploit
to take over the simulator's webcam (assuming the simulator didn't patch and
revert). Universal buffer overflow!

------
asdflkj
The idea that science should even come up with an "alternative" to that
bullshit is an insult to science.

~~~
swombat
Not to mention that the multiverse theory can't currently be proven wrong and
hence is unscientific.

~~~
yummyfajitas
True, neither multiverse theory nor a singleverse theory can be proven. But
both are scientific in the sense that they (sort of) predict the structure of
our universe. The question then becomes how to select one of the theories.
Occams razor provides little help, since both theories are similarly complex,
so one possible way to select a theory is to use Bayes rule. I'll sketch this
reasoning:

The laws of physics are governed by equations which output only a probability
distribution P(x) for various quantities (positions of particles, the values
of certain fundamental constants).

(Note: I really don't understand any of this stuff well, so if someone (Dani?)
with better knowledge can correct me or clarify, I'd love to see it.)

In a single-universe theory (SUT), one postulates that a particular x is
selected, at random, relative to P(x) dx. In this theory, it is highly
unlikely that the universe can support life (or at least life like us). In a
multiverse theory (MUT), one postulates that all x are selected in parallel.
In this case, our particular x _will be chosen_ ; the fact that we live in a
good universe is not luck, merely natural selection. So the probability we
exist is close to 1.

Both these theories are more or less equally "simple" (think Kolmogorov
complexity), so let us _assume_ they each "occur" with the same or similar
"probability" (i.e., p(SUT)=p(MUT)=1/2). Then we use Bayes rule:

p(SUT | we exist) = p(we exist | SUT) p(SUT) / p(we exist) = (really freakin
low) (1/2) / (1/2+really freakin low) = (unlikely)

p(MUT | we exist) = p(we exist | MUT) p(MUT) / p(we exist) = (almost 1) (1/2)
/ (1/2 + really freakin low) = (highly likely)

So multiverse theory is more "probable" than single universe theory. This
remains true even if you wildly alter the complexity of competing theories,
e.g. p(SUT)/p(MUT) = 1e6.

It's true, we can never falsify SUT or MUT relative to each other. But we can
make educated guesses as to which one is more "probable". And yes, this is
pretty sketchy, hence my use of scare quotes everywhere. But it's the best we
can do right now.

Note: I computed p(we exist) = p(MUT)p(we exist | MUT) + p(SUT)p(we exist) =
(1/2) 1 + (1/2)(really freakin low).

[edit: just curious why I'm being downmodded. Not begging for upmods, I'm
honestly curious. Did I make a mistake here?]

~~~
swombat
I guess for lack of scientific rigour? Theories aren't scientific because of
the maths, they're scientific because of the approach, which involves creating
testable hypotheses that can be determined to be right or wrong. The reason
why these two are not scientific theories is not because no one can come up
with some maths to support them, but because there is no way to observe them.

I did a physics degree. I studied atomic physics and quantum mechanics. We
briefly brushed on the multi/single universe, but largely that was not
examined in too much detail in the physics cursus. People who were doing
Physics & Philosophy, however, got plenty of detail in their course. My point
being: this is philosophy, not science.

[edit: my turn to wonder why _I_ am being downmodded, lol]

~~~
yummyfajitas
Both theories _are_ testable. They both (sort of) successfully predict the
structure of the universe, up to some parameter choices (e.g., fine structure
constant). There are ways to falsify both theories _simultaneously_ since they
make nearly the same predictions, we just don't have ways to falsify one but
not the other.

The question is 'absent plausible experiments, how do we choose _between_
single and multiple universes?' And that is done using occams razor; the
'simpler' or 'more probable' theory is chosen, for a somewhat (but not
completely) arbitrary definition of 'simpler'.

Occams razor is a philosophical point, as is (to some extent) your definition
of 'simpler'. I thought I was careful to highlight those points.

I was merely trying to explain the reasoning multiverse theory, but in a less
vague manner than the article did (I trust most of HN to know Bayes rule).

Incidentally, this thread is bringing out behavior which is weird for HN.
Someone downmodded your comment, also for reasons which are completely
inscrutable to me.

------
river_styx
If I recall correctly, the "universe" is a concept meant to encompass all that
exists. How then can there be multiple universes? Wouldn't the set of all
universes itself exist within the universe?

It seems more likely to me that "universe" here is being defined as "what we
can observe", in which case these multiverses are simply the unobservable part
of our universe.

~~~
r7000
"Universes" in this context means discrete space-times with potentially
_different physical constants_ where the laws of physics would be different.
<http://en.wikipedia.org/wiki/Multiverse#Bubble_theory>

The Many-Worlds hypothesis also implies separate "realities" ("universes"?)
diverge with every quantum measurement.

The word is used for convenience.

~~~
river_styx
I guess that's part of my objection, really. The use of the word "universe"
implies that there is only one of them, as the prefix "uni-" in Latin means
"one".

------
elemenohpee
I don't think the idea that the universe is finely tuned for life(not
necessarily life as we know it) is that unreasonable. I dislike the idea of a
creator for the obvious reason that you run into an infinite regression. What
created the creator, etc... So how do we get around this? Could it be possible
that the universe created itself? In the void, there are infinite
possibilities. If there existed a pattern which sustained itself, somehow
propagated itself in perpetuity, would it then exist? Then the fact that the
universe seems finely tuned for life would be an obvious consequence.
Something like us would be needed to tend the light, we would be a necessary
component of this pattern. Anyway, I like it better than the idea of a huge
number of "dead" universes, although I doubt we'll ever know the Truth of the
matter.

------
markessien
The solution is too complex. Complex things don't survive, because complexity
tends to decay. The universe has to be based of a very simple concept - but
our minds, which are developed for earth-style biology has not yet landed on
that concept.

I'll consider any theory seriously that is:

1\. Very simple

2\. Very stable

~~~
crabapple
_The universe has to be based of a very simple concept_

why?

~~~
markessien
Because everything we have ever observed in nature follows the exact same
pattern:

1\. Single instable thing exists that tends to combine with other items to
form a somewhat stable object

2\. The results combine with other more complex things in the same manner to
create something else

It's like a recursion. Something simple gets executed over and over again,
each time gaining in parameters and complexity.

------
wensing
Is the multiverse theory falsifiable? I can't tell.

~~~
DarkShikari
To some extent, actually, yes. Here's a way of doing it.

Let us say that a hyper-advanced civilization has the ability, through
simulations or otherwise, of calculating the odds of life arising in a
universe with given initial conditions and fundamental constants (to some
rough accuracy). They can test billions of possible initial states, including
our own, and use that to see whether we lie in a very probable location in
phase space or an improbable one. If the location is probable, it strongly
supports the multiverse theory.

If the location is improbable, the theory is likely false. For example, if the
average probability of life arising in a given universe in some chunk of phase
space that includes ours is 40%, and ours is in a subsection of that phase
space with a 30% probability, the multiverse theory is not falsified. If ours
is in a subsection of that phase space with a 0.000001% probability (far lower
than average), it suggests that multiverse is unlikely, because our existence
seems to be in violation of pure chance.

The same method can be used to falsify evolution. Test billions of simulations
of the Earth's development of life, and see where our species falls
statistically. If we're in a probable area of the phase space (phase space of
possible sentient creatures to evolve), our understanding of evolution is
likely correct, and if we're in a very improbable area (many many standard
deviations away from the most likely), our understanding must be flawed
somewhere.

~~~
swombat
Down-modded for basic misunderstanding of the scientific method.

~~~
DarkShikari
Exactly how? Or are you just going to respond with a useless one-liner rather
than actually explain your objection?

Statistical analysis of probabilities is a method of analyzing the odds of a
theory's validity. _If a theory requires that reality be extremely improbable,
that theory is highly unlikely._ And when there's absolutely nothing else you
can do, its the only option other than blind faith.

I'll repeat this again:

 _If a theory requires that reality be extremely improbable, that theory is
highly unlikely._

The _entire point_ of the Anthropic Principle is to attempt to answer this
question by stating that if reality was not improbable as such, we wouldn't
exist to ask that question.

Do you object to this concept? How is this concept a violation of the
scientific method?

~~~
swombat
I warmly invite you to consult the wikipedia page on the scientific method:

<http://en.wikipedia.org/wiki/Scientific_method>

In it, you will find the "essential elements" of the scientific method:

    
    
        * Characterizations (observations, definitions, and measurements of the subject of inquiry)
    
        * Hypotheses (theoretical, hypothetical explanations of observations and measurements of the subject)
    
        * Predictions (reasoning including logical deduction from the hypothesis or theory)
    
        * Experiments (tests of all of the above)
    

The last two elements are missing from your approach, and it is hence
unscientific.

Please note that the anthropic principle is not a scientific theory, it is a
wild guess at why things might be what they are.

 _If a theory requires that reality be extremely improbable, that theory is
highly unlikely._

This is a very wild conjecture with no substantiating evidence. It is wholly
equal to blind faith, and in no way superior to it.

~~~
DarkShikari
_Please note that the anthropic principle is not a scientific theory, it is a
wild guess at why things might be what they are._

 _It is wholly equal to blind faith, and in no way superior to it._

So, by your logic, the anthropic principle is wholly equal to blind faith?
Sure, its not strictly science, and more of a logical argument than a
scientific experiment (much like my original post), but _really?_ _Equal to
blind faith?_

If you are that deluded, I'm not even going to bother arguing this. This is
pointless. Go get yourself a source a bit better than Wikipedia and educate
yourself.

~~~
swombat
Wikipedia has become a fairly good reference for these sorts of basic
principles.

In terms of intellectual "worth thinking about"-ness, the anthropic principle
may be more worthwhile than blind faith, but in terms of science, it is
equally worthless.

You need to revise your understanding of how science works, or else you'll
only continue to blunder around.

------
trapper
They should get blossom goodchild to ask the galatic federation of light,
perhaps they know :P

------
speek
Isn't this a major part of string theory?

------
crabapple
there's a lot of talk of probabilities in the article but it seems hackneyed

the universe has almost countless variables that can result in near-infinite
states, but there is a 100% chance that _one_ state must emerge (i.e. a 100%
chance that reality exists), and it isn't clear if the alternative scenarios
they describe (particles of different masses, stronger gravitational impact on
stellar mass) are more probable than our own. the scientists see our state as
optimal because we live in it, but why couldn't our state be suboptimal? maybe
there was a potential state (never realized) that resulted in us all being
omnipotent. there seems to be a bias from the researchers regarding our own
state, but they haven't demonstrated that its any more or less likely than any
other outcome

