i)
Old-style Physics

ii)
Galileo

iii)
Einstein

iv)
Pythagoreanism

v)
The Beauties and Symmetries of String Theory

vi) String Solutions and the Multiverse

**[All unlinked quotes are from Michio Kaku's**

__.]__*Parallel Worlds*
Much
has been made of string theory being “unscientific”, lacking
evidence and not offering unique predictions. This piece lays part of the blame at the Pythagorean nature of string theory (in which the mathematics always has a supreme
position).

The
first section tackles what's called “old-style physics” - that is
physics that places an importance on observation, experiment and
prediction. Then there's a section in which Michio Kaku ties his own
position to the science of Galileo and then Einstein. In both cases,
it can be seen that they aren't great exemplars for string theory.

The
central section deals with Pythagoreanism and how it ties in with
string theory. The next section deals with the aesthetics of string
theory and argues that aesthetic appeal can't be – and mustn't be -
the end of the story in physics.

Finally,
there's a section which cites a specific example of how string theory
mathematics can lead to string theory physics and cosmology: i.e.,
the case of string solutions and the multiverse.

***************************************

Michio
Kaku is an American theoretical physicist and populariser of science.
He is a professor of theoretical physics in the City College of New
York and CUNY Graduate Center.

**Old-style Physics**

The
main contention
of this piece is that string theory is essentially Pythagorean in
nature. String theory has also been described
as

**“postmodern” by the theoretical physicist**__Lee Smolin__. In terms of the latter description, this doesn't mean*postmodern*in the philosophical sense practised by philosophers like Jean Baudrillard, Jean-François Lyotard, etc.: it simply means*after*modern physics. That is, this is how physics was done when string theory arrived. (Having said that, no doubt Smolin was aware of the philosophical associations of this term.) Smolin__puts it this way__:
“The
feeling was that there could be only one consistent theory that
unified all of physics, and since string theory appeared to do that,

*it had to be right*. No more reliance on experiment to check our theories. That was the stuff of Galileo. Mathematics [alone] now sufficed to explore the laws of nature. We had entered the period of postmodern physics.”
“For
the first time in its history, theory has caught up with experiment.
In the absence of new data, physicists must steer by something other
than hard empirical evidence in their quest for a final theory.”

Kaku himself (though
talking about cosmology in the 1960s) also uses words which are
perfectly apt for string theory. He
writes:

“[Cosmology/string
theory] was not an experimental science at all, where one can test
hypotheses with precise instrument, but rather a collection of loose,
highly speculative theories.”

Kaku
also

**tells us how physics used to be before string theory****:**
“In
the past, physics was usually based on making painfully detailed
observations of nature, formulating some partial hypothesis,
carefully testing the idea against the data, and then tediously
repeating the process, over and over again.”

Despite
the above being a very simplified picture (which Kaku wouldn't deny),
Kaku pits it

**against the approach employed by string theorists. Kaku continues:**
“String
theory was a seat-of-your-pants method based on simply guessing the
answer. Such breathtaking shortcuts were not supposed to be
possible.”

Just
as it was said that Kaku's account of “old-style” physics is
simplified, so we can say that same about his account of the early
days of string theory (despite him being an important member of that
group). Nonetheless, despite these simplifications and exaggerations,
Kaku and many others are well aware that string theory is seen as being both
postmodern and Pythagorean. So it seems odd (at least

*prima facie*) that a string theorist would admit that string theory was based on “simply guessing”. Then again, guessing (or at least*speculation*) has always been a part of physics. So string theory isn't unique in that respect. And even critics of string theory may have a problem with that emotive word – i.e., “guessing”.
Anyway,
even according to a string theorist himself (i.e., Kaku), whereas
old-style physics involved observations, tests and experiments;
string theory is about maths... and guessing.

Not
only is string theory seemingly more dependent on maths than other
areas of physics (though that can be debated), it seems that some
physicists even see string theory as being a branch of mathematics.
Kaku doesn't hide from this because he quotes a “Harvard physicist”
saying as much. In Kaku's own words:

“One
Harvard physicist has sneered that string theory is not really a
branch of physics at all, but actually a branch of pure mathematics,
or philosophy, if not religion.”

That
Harvard physicist was “Nobel Laureate

__Sheldon Glashow__”. So can we now play Kaku's emotive word “sneered” against Glashow's equally emotive word “religion”?
We
can see that although string theory has an

__hegemony in physics__(at least according to Lee Smolin, Sheldon Glashow and other physicists), there are some physicists who are very unhappy with this. Kaku again puts the case of the Opposition in this respect. According to**Kaku, Glashow****“compar[ed] the superstring bandwagon to the Star Wars program (which consumes vast resources yet can never be tested”.**
Glashow then got technical when he also
said
(at least according to Kaku) that

“string
theory will dominate physics the same way that Kaluza-Klein theory
(which he considers 'kooky') dominated physics for the last fifty
years, which is not at all.”

Of
course talk of the

__Kaluza-Klein theory__(__“which posited a fifth dimension”__) is relevant here because that was the theory which introduced an extra dimension into physics. That may mean that Glashow believes that the rot actually set in during the 1920s.**Galileo**

Kaku
mentions Galileo in support of his Pythagorean position. (Kaku never uses the word 'Pythagorean' about his own position.)

Galileo
was also at least partly Pythagorean in that he noted the vital
importance of numbers in physics. Yet he was also fundamentally un-Pythagorean in the respect that he often moved

*from the world to the maths*- rather than vice versa. That is, he both observed the world and carried out experiments; which**the Pythagoreans never did. Thus it’s no surprise that Kaku quotes this well-known passage from Galileo:**
“'[The
universe] cannot be read until we have learned the language and
become familiar with the characters in which it is written. It is
written in mathematical language, and the letters are triangles,
circles, and other geometrical figures, without which means it is
humanly impossible to understand a single word.'”

Galileo
is basically saying that mathematics comes first. That is, “until we have
learned the language and become familiar with the characters in which
it is written”, we simply can’t understand the universe. However,
that didn't stop Galileo from moving in both directions: from

*maths-to-world*and then from*world-to-maths*. (The same is true of the comments from Einstein later.) This hints at the conclusion that the*either maths-to-world or world-to-maths*idea is, in fact, a false__binary opposition__. At least it's a false binary opposition when it comes to Galileo and, later, Einstein. However, it may be a true binary opposition when it comes to Pythagoreans, strings theorists and Max Tegmark (see later comments).
In
addition, perhaps I'm doing Galileo a disservice here because he did
say that

“we
cannot understand [Nature] if we do not first learn the language and
grasp the symbols in which it is written”.

Yes,
Galileo was talking about our

*understanding*of Nature - not just Nature as it is (as it were) “in itself”. Nonetheless, Galileo also said that the “book is written in mathematical language”. So was he also arguing that Nature*as it is in itself*is mathematical? That is, perhaps Galileo wasn't only saying that mathematics is required to*understand*Nature.
There
is, therefore, an ambivalence here between the following:

i)
The idea that Nature

*itself*is mathematical. And
ii)
The idea that mathematics is required to

*understand*Nature.
Surely
we must now say that “Nature's book” isn't written in the
language of mathematics. Sure, we can say that Nature's
book

*can*be written in the language mathematics. (Indeed it often is written in the language of mathematics.) Though Nature's book is not*in itself*mathematical because that book - in a strong sense - didn't even exist until human beings began to write (some of) it.**Einstein**

After
Kaku puts the Pythagorean position, he then mentions Albert Einstein.
He quotes Einstein (as backup)
stating the following:

“'I
am convinced that we can discover by means of purely mathematical
construction the concepts and the laws… which furnish the key to
the understanding of natural phenomena.'”

Einstein
went deeper when he added these words:

“'Experience
may suggest the appropriate mathematical concepts, but they most
certainly cannot be deduced from it.'”

Now
all this does indeed sound rationalist or Pythagorean – at least on
the surface. And Einstein more or less came clean about this in his
final sentence. Thus:

“'In
a certain sense, therefore, I hold it true that pure thought can
grasp reality, as the ancients dreamed.'”

Yet
doesn't all this seem back to front? That is, Einstein claimed to be
working from a “purely mathematical construction” and from there
he went on to discover new “concepts and laws”. In other words,
mathematical concepts “furnish[ed] the key to the understanding of
natural phenomena”.

Nonetheless,
it's not a (purely) rationalist position to claim that mathematical
concepts can “furnish the key to the understanding of natural
phenomena”. Basically, most (or even all) physicists would accept
that. However, claiming that through “pure thought”

*alone*we can “grasp reality” is surely a rationalist position. Then again, pure rationalists wouldn’t say that “experience may suggest the appropriate mathematical concepts”. And they would rarely talk of “natural phenomena”. So, in that sense, it’s clear that pure rationalism is a rare position. And it’s even rarer when it comes to physicists (i.e., rather than philosophers).
This
means that in the Einstein passage above there's a subtle merging of
rationalism and empiricism - in a

__Kantian____mode__. That Kantian mode is best expressed in this sentence from Einstein:
“Experience
may suggest the appropriate mathematical concepts, but they most
certainly cannot be deduced from it.”

This
suggests (in a true Kantian spirit) that the mathematical concepts
are already there (as it were) in the human mind and only then do the
observations of physicists help to tease them out. In any case, Kant
certainly incorporated
what Einstein called “mathematical concepts” into his “

*a priori*reasoning”.
Does
this

*off-piste*journey into Einsteinian rationalism validate Kaku’s previously-quoted claim? (The claim that “verification of string theory might come entirely from pure mathematics, rather than experiment”?) Probably not. That's primarily because Kaku doesn’t elaborate on his philosophical position (as Einstein does). The other thing is that many of Einstein’s forays into philosophy aren't very sophisticated. That’s not a surprise since he wasn’t a philosopher. Thus the quote above may well contain contradictions or unclear reasoning. It’s also the case that Einstein often changed his philosophical positions throughout his life.
For
example, Kaku again mentions Einstein (in the same book) stating
this:

“Einstein
once said that if a theory did not offer a physical picture that even
a child could understand, then it was probably useless.”

On
the surface, Einstein’s position here is far from being rationalist
or Pythagorean. Indeed even an hard-core empiricist probably wouldn’t
feel the need to go as far as Einstein did (at least at that moment
in his career). An empiricist may concede that “physical
interpretations” of theories or mathematical concepts are
important. However, we shouldn’t get too fixated on mental imagery
or “physical picture[s] that even a child could understand”.

And
here's another example which Kaku conveniently offers us. This time,
however, it's Kaku talking about Einstein's position. Kaku

**writes:**
“To
Einstein, any solution of his equations, if it began with a
physically plausible starting point, should correspond to a
physically possible object.”

This
again shows Einstein in non-rationalist mode and perhaps it works as a warning to string theorists. It also squares perfectly
well with the astrophysicist and writer

__John Gribbin__on the same subject.__Gribbin says__that “a strong operational axiom” tells us that
“literally
every version of mathematical concepts has a physical model
somewhere, and the clever physicist should be advised to deliberately
and routinely seek out, as part of his activity, physical models of
already discovered mathematical structures”.

When
it comes to Einstein's possible philosophical confusions, it's worthwhile noting that Kaku also quotes Einstein's warnings against
philosophy. Einstein is quoted as stating

*the following*:
“'Is
not all of philosophy as if written in honey? It looks wonderful when
one contemplates it, but when one looks again it is all gone. Only
mush remains.'”

So
perhaps Einstein should have heeded his own warning.

**Pythagoreanism**

As
for the “accusation” of Pythagoreanism (if it is an accusation),
don’t take my word for it. Take the words of Michio Kaku himself.
Firstly Kaku

**lays out the essential Pythagorean position:**
“Not
surprisingly, the Pythagoreans’ motto was ‘All things are
numbers.’ Originally, they were so pleased with this result that
they dared to apply these laws of harmony to the entire universe.”

Then
Kaku continues by saying that “with
string theory, physicists are going back to the Pythagorean dream”.

As
will be expressed later in this piece, the intellectual move for the
Pythagoreans (at least as Kaku expressed it) was from maths (or
“numbers”) to the universe/world/reality, rather than from the
universe/world/reality to maths. That is, the maths came first and
only after was it applied to the universe/world/reality.

The
question we must now ask is this:

What
is it for “things” to be “numbers”?

This
isn’t to only to state that maths can describe “things” –
it’s to say that “things [literally] are numbers”. But what
does that actually mean? As with

__Max Tegmark__(who endorses this position), we can ask it the statement “All things are numbers” is to be taken poetically or literally. Taken literally, it hardly makes sense. Taken poetically, it still requires interpretation.
One
interpretation of both Tegmark's and the Pythagorean positions is that
if things literally are numbers, then it’s no surprise that string
theory is on top of

*things*when it comes to describing reality. I mean that in this sense:
i)
If

*things*are numbers,
ii) and numbers describe things (which are numbers),

iii) then numbers are describing numbers.

So
we never escape from the world of numbers; which is, I suppose,
precisely the result which Pythagoreans want. Yet we still don’t
really know (for sure) what the statement “All things are numbers”
means.

To
change
tack
a little.

The
physicist

__John Archibald Wheeler__provided the best riposte to Pythagoreanism in physics. We're told that Wheeler used to write many arcane equations on the blackboard and stand back and say to his students:
“Now
I'll clap my hands and a universe will spring into existence.”

According
to Pythagoreans, however, the equations

*are*the universe.
Then
Steven Hawking trumped Wheeler with an even better-known quote.

__He wrote__:
“Even
if there is only one possible unified theory, it is just a set of
rules and equations. What is it that breathes fire into the equations
and makes a universe for them to describe?”

The
science writer

__Kitty Ferguson__offers a (possible) Pythagorean answer to Hawking's question when__she says__that “it might be that the equations are the fire”. Alternatively, could Hawking himself have been “suggesting that the laws have a life or creative force of their own?”. Again, is it that the “equations are the fire”?
So
what, exactly, “breathes fire into the equation [to] make a world”?

To
return to string theory.

Kaku
himself puts what can be seen as the extreme place which string
theory finds itself in. He
writes:

“My
own view is that verification of string theory might come entirely
from pure mathematics, rather than from experiment.”

This
is hard to even understand. That may because I’ve read too much
philosophy and find the use of the words “verification” and
“mathematics” together odd. That isn’t a problem if Kaku means
“proof” by “verification”. Whatever the case may be, it’s
clear that he doesn’t mean

*observational*or*empirical*means of verification. After all, Kaku himself finishes off with the words “rather than from experiment”.
So
is string theory is about the physical world? Yes?

It's
true that all physics employs mathematics. However, such physics is
still

*about the physical world*. Therefore how can the “verification of string theory [come] entirely from pure mathematics”? (Note the term__“____pure mathematics”__, not “applied mathematics”.) How would that work?
Despite
all of the above, string theorists haven’t got a complete hegemony.
Kaku happily acknowledges this and cites various cases. For example,
the chance meeting of the theoretical physicist

__John Schwarz__and Richard Feynman. Kaku**writes:**
“String
theorists became the butt of jokes. (John Schwarz remembers riding in
the elevator with Richard Feynman, who jokingly said to him, ‘Well,
John, and how many dimensions do you live in today?’”

Feynman’s
witty remark didn’t necessarily mean that he was against string
theory. After all, this exchange occurred in the early days of string
theory (Feynman died in 1988). In addition, Feynman's

__“sum over paths”__is hardly a walk in the park.
Of
course we need to establish whether or not there’s a strong
connection between the fact that string theory is highly mathematical
and that corresponding fact that string theorists believe some pretty
outlandish things about the universe (or multiverse).

**The Beauties and Symmetries of String Theory**

Much
is made of the fact that many mathematicians and physicists stress
the “beauty” and “elegance” of their theories. In terms of
string theory, perhaps these aesthetic values may provide string
theory's main appeal.

Kaku explicitly defines
(mathematical) beauty thus:.

“When physicists speak of 'beauty' in their theories, they really mean that their
theory possesses at least two essential features: 1. A unifying
symmetry 2. The ability to explain vast amounts of experimental data
with the most economical mathematical expressions.”

Then
Kaku quotes the physicist and astrophysicist

__saying as much. (Though he''s talking about inflation, not string theory!) Primack said:__**Joel Primack**
“No
theory as beautiful as this has ever been wrong before.”

It
would be an empirical fact if that were true. However,

__Lee Smolin__, for one, has warned physicists about paying to much homage to mathematical beauty. (__Roger Penrose__has also warned about this in his*Road to Reality**,*chapter 34)
Smolin
quotes string theorists talking about the beauty of the theory

__in the____following__:
“...
'How can you not see the beauty of the theory? How could a theory do
all this and not be true?' say the string theorists.”

Smolin
is at his most explicit when he also tells us that “string
theorists are passionate about is that the theory is beautiful or
'elegant'”. However, he says that

“[t]his
is something of an aesthetic judgment that people may disagree about,
so I'm not sure how it should be evaluated”.

Smolin
concludes:

“In
any case, [aesthetics] has no role in an objective assessment of the
accomplishments of the theory.... lots of beautiful theories have
turned out to have nothing to do with nature.”

Perhaps
Smolin is going too far here. Surely it's the case that aesthetics
has at least some role to play when it comes to

*theory-choice*. And who's to say that whether a theory is elegant or not – at least in some sense - isn't itself an “objective” issue? Whether something is simpler than another theory is surely an objective fact. It's whether or not such simplicity can also be directly tied to elegance, beauty and*truth*that's the issue here.
In
addition to that, as evolutionary psychologists and cognitive
scientists have told us, human beings have an innate need for both
simplicity and explanation – sometimes (or even oftentimes) at the
expense of

*truth*. Thus, in the case of string theory, we may have a juxtaposition of the psychological need for simplicity and explanation along with highly-complicated and arcane mathematics.
So
perhaps that highly-complicated maths is but a means to secure us
simplicity and explanation. That is, the work done towards simplicity
and explanation is very complex and difficult; though the result –
a theory which is both simple and highly explanatory – evidently
isn't.

All this means that the statement “beauty is truth” may not itself be a truth. Or at
least it may not always be applicable to every mathematical or
physical theory.

And
just as the two-way direction of

*world-to-maths*or*maths-to-world*has been discussed, so we have a similar idea with beauty. This is how Kaku puts it:
“When
you come up with a theory, you fall in love with the beauty the
simplicity and elegance of it. But then you have to get a sheet of
paper and pencil and crack out all the details. Hundreds and hundreds
of pages. Because you have to prove it.”

Here
Kaku (or other physicists) firstly notes “the beauty, simplicity
and elegance” of a theory. And only then does he “get a sheet of
paper and pencil and crack out all the details”. So beauty is first
spotted (as it were), and only then does the physicist needs to
“prove it” - that is, show that beauty is also truth/correctness.
But, again, the beauty of a mathematical theory comes first. Thus
beauty in and of itself (as it were) entails
(to use a strong word)
truth.

Yet talk of beauty by
physicists is very off-putting because their views of beauty don't
really coincide with the layperson's – except when it comes to
symmetry and simplicity. But even here the way that physicists use the
words “symmetry” and “simplicity” will not strike many chords
with many laypersons. But perhaps that simply doesn't matter.

Kaku offers us a
very specific case
of

*beauty-vs.-ugliness*in the following account of Maxwell's equations:
“Maxwell's
equations... originally consisted of eight equations. These equations
are not "beautiful." They do not possess much symmetry. In
their original form, they are ugly. ...However, when rewritten using
time as the fourth dimension, this rather awkward set of eight
equations collapses into a single tensor equation. This is what a
physicist calls 'beauty,' because both criteria are now satisfied.”

Clearly, beauty is being
strongly connected to symmetry. And, of course, string theory and

__M-theory__**offer us much symmetry. In architecture and music, symmetry can be very important. Indeed they may partly constitute beauty. What about simplicity? That depends. Aesthetics is a tricky road to go down if one isn't an artist or aesthetician.****String Solutions and the Multiverse**

Let's
give one specific example of how the physics of string theory grew
out of the mathematics of string theory.

In
the mid-1990s, billions of solutions of what are called the

__string equations__were discovered. The important and relevant point to make about this situation was that all those billions of solutions “corresponded**to a mathematically self-consistent universe”. This had a concrete effect, then, on physics itself and especially on string theory. As Kaku tells the story:**
“The
bewildering numbers of string solutions was actually welcomed by
physicists who believe in the multiverse idea, since each solution
represents a totally self-consistent parallel universe.”

Interestingly
enough, Kaku continues by
saying
that

“it
was distressing that physicists had trouble finding precisely our own
universe among the jungle of universes”

Put
that way, it’s as if this “jungle of universes” grew solely out
of the maths. That is, firstly we had billions of string solutions,
and only then we had “billions of self-consistent parallel universe[s]”.
This raises the question as to how many physicists believed in the
multiverse theory before the mid-1990s (i.e., when these string
solutions were discovered). The way that Kaku puts it (which may be a
simple grammatical misreading) is that there were physicists who
already believed in the multiverse - and then these string solutions
came along to back up their prior beliefs. That is, Kaku wrote that
“[t]he bewildering numbers of string solutions was actually
welcomed by physicists who believe in the multiverse idea”. Does
this mean that before the 1990s physicists had neither mathematical
nor physical reasons to believe in the multiverse? Or did previous
mathematical tricks (which helped bring the multiverse into
existence) already exist before that time?

So what do physicists mean by “beauty”? Here Kaku helps us out
again. He
writes:

“To
a physicist, beauty means symmetry and simplicity. If a theory is beautiful, this means it has a powerful symmetry that can explain a
large body of data in the most compact, economical manner. More
precisely, an equation is considered to be beautiful if it remains
the same when we interchange its components among themselves.”

Of
course string theory and M theory contain many symmetries. So does that mean that string
theory (or string theories) must be beautiful? However, despite these
positive words, Kaku does go on to say
the following:

“Symmetries
then encode the hidden beauty of nature. But in reality, today these symmetries are horribly broken. The four great forces of the universe
do not resemble each other at all. In fact, the universe is full of irregularities and defects...”

Despite
the fact that Kaku makes much of symmetry and supersymmetry, he’s
still happy to acknowledge “at present there is absolutely no
experimental evidence to support it”. Then again, he does conclude
by saying
that

“[t]his
may be because the superpartners of the familiar electrons and
protons are simply too massive to be produced in today’s particle
accelerators”. (This was written in 2005.)

Is
this is a clear case of supersymmetry wagging the dog (as it were)?
Nonetheless, one can see the “beauty” of supersymmetry and the
consequential urge to embrace it. Kaku sells it
like this:

“When
one adds supersymmetry [to the Standard Model], however, all three
forces fit perfectly and are of equal strength, precisely what a
unified field theory would suggest.”

But
then comes a warning sign:

“Although
this is not direct proof of supersymmetry, it shows at least that
supersymmetry is consistent with known physics.”

So
here we have mathematical and physical consistency again. Like the
possible worlds of philosophers, all these things are indeed

*logically possible*. Zombies and trees with a sense of humour are also logically possible: but are they actual?
.

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