Exponential Growth an Illusion?: Response to Ilkka Tuomi
Ray Kurzweil responds to Ilkka Tuomi's essays, "The Lives and Death of Moore's Law" and "Kurzweil, Moore, and Accelerating Change," in which Tuomi challenges Kurzweil's "law of accelerating returns" and the exponential growth of semiconductor technology.
Published on KurzweilAI.net Sept. 23, 2003. See also The
Lives and Death of Moore's Law and Kurzweil,
Moore, and Accelerating Change (pdf) by Ilkka Tuomi.
In his detailed analysis "The Lives and Death of Moore's Law,"
Ilkka Tuomi concludes that the "semiconductor industry has not actually
followed an exponential growth trend" and "price decreases have
not followed an exponential trend."1
Tuomi's conclusions are surprising, to say the least. If correct,
I would have to conclude that the one-quarter MIPS computer costing
several million dollars that I used at MIT in 1967 and the 1000
MIPS computer that I purchased recently for $2,000 never really
existed. Tuomi has an explanation for all this. He writes that
"the apparent explosive big bang in semiconductor technology is
. . . an illusion."2
If all of this is an illusion, it has been quite an effective one.
The reality is that Tuomi's conclusions defy common sense and clear
observation. They are at odds with the historical data on the past,
as well as all of the industry road maps for the future.
Tuomi's approach is to set up a variety of straw men in the form
of faulty interpretations of Moore's Law and then proceed to show
how certain data fail to match these incorrect interpretations.
When presented with a "forest" of data representing a clear exponential
trend, Tuomi often cites a tree with a missing branch (see my discussion
below on Tuomi's critique on my history of the computing trend over
the past century). Tuomi supports his contrarian contentions with
a list of often conflicting technical terminology and irrelevant
historical anecdotes. There are a variety of misconceptions in
Tuomi's two papers, which I detail in this response essay.
Despite a plethora of misconstructions in the data that Tuomi presents,
his analysis is nonetheless replete with exponential trends. Tuomi's
remarkable conclusion that the semiconductor industry has not followed
an exponential trend is not consistent with his own analysis.
Tuomi repeatedly points out how the advances have not followed
the oft-quoted 18-month doubling time of Moore's Law. Tuomi is
correct that the 18-month figure is a mischaracterization. Moore
never said it, and it does not necessarily match the data (depending,
of course, on what you're measuring). Tuomi devotes a lot of his
paper to showing how the 18-month figure is not correct, at least
for certain measurements. He quotes a lot of people, such as R.X.
Cringely in 1992, who have gotten it wrong3.
But the fact that many people state Moore's Law incorrectly does
not mean that there is not a correct way to state it, and it certainly
does not follow that there has not been exponential growth.
Moore's Law refers to the continual shrinking of the size of transistors
on an integrated circuit, as well as other process and design improvements.
This shrinking increases the number of transistors that can be placed
on a chip, as well as their speed, resulting in dramatic exponential
gains in the price-performance of electronics.
My law of acceleration returns is broader, and refers to ongoing
exponential improvements in the price-performance and capacity of
information technologies in general, of which Moore's law is just
one example. I provide further explanation and examples below.
Tuomi writes that
"During the four decades of validity often claimed for
Moore's Law the difference between one-year and three-year doubling
time means about eight orders of magnitude. In other words, to get
the same number of transistors, the slower growth path would require
us to buy 100 million chips, instead of one."4
I would certainly agree that there is an enormous difference in
implications between a one-year and a three-year doubling time.
However, there is no such variability in the data, unless one is
trying to create confusion. Whether one gets a 36-month doubling
time or a 12-month doubling time, or any other doubling time, depends
entirely on what is being measured. If measuring something simple
like two-dimensional feature size, then the doubling time (toward
smaller features) is about 36 months.5
This has nothing to do, however, with cost-effectiveness or price-performance,
which is what we really care about. The cost per transistor has
fallen by half about every 1.6 years. If one takes into consideration
all of the levels of improvement including speed, as I describe
below, then the doubling time for price-performance is closer to
one year.
Regardless of the doubling time, the trends are all exponential,
not linear, both in the historical data, and in the roadmaps for
the future. Tuomi's point about the difference between 36 months
and 12 months as a doubling time is based entirely on comparing
apples to watermelons, or in this case, cell sizes to actual price-performance
improvements.
Let's examine these issues in more detail. I'll start with my
own four-plus decades of experience in this industry. Compare the
MIT computer I mentioned above to my current notebook. As a student
in 1967, I had access to a multi-million dollar IBM 7094 with 32K
(36-bit) words of memory, and a quarter of a MIPS processor speed.
I now use a $2,000 personal computer with a quarter billion bytes
of RAM and about a thousand MIPS processor speed. The MIT computer
was about a thousand times more expensive, so the comparison with
regard to the cost per MIPS is a factor of about 4 million to one.
Click for larger version.
This ignores many other advantages of my contemporary computer.
Ignoring these other significant factors of improvement, the contemporary
computer provides MIPS of processing at a cost that is 222
lower than the computer I used in 1967. That's 22 doublings in
36 years, or about 19 months per doubling. If we factor in the
increased value of the approximately 2,000 fold greater RAM memory,
vast increases in disk storage, the more powerful instruction set
of my circa 2003 computer, vast improvements in communication speeds,
more powerful software, and other factors, the doubling time comes
down even further.
Consider microprocessor history. The Intel 8080 had 5,000 transistors
in 1974. The Pentium IV had 42 million transistors in 2000. That's
just about exactly 13 doublings in 26 years, which is a two-year
doubling time. Keep in mind that this two-year doubling time takes
into consideration only this single factor of the number of transistors.
If we also factor in the fact that the smaller Pentium IV transistors
operate many times faster and are organized with many layers of
circuit innovation, then the overall price-performance improvement
is greater than 213. The graph (of number of transistors)
of the intervening processors (such as 8086, 286, 386, 486, Pentium,
Pentium 2, etc.) shows smooth exponential growth (R2
= 0.9873).6
Click for larger version
We should also keep in mind that adding transistors to a microprocessor
is not the sole or even the primary goal of semiconductor technology.
At a certain point in the future, we will have the optimal complexity
for a single processor. We will continue to want to improve price-performance,
but not necessarily number of transistors in a single microprocessor.
Thus the International Technology Roadmap for Semiconductors (ITRS)
projects the number of transistors in a single microprocessor to
double every 36 months through 2016, but also projects the cost
of a single microprocessor to come down such that the cost per transistor
in a microprocessor is coming down by half every 24 months. Even
this figure ignores the speed improvement factor, which I discuss
below.
Data from Dataquest and Intel shows that the average price of a
transistor per year went from 1 dollar in 1968 to about 2 x 10-7
dollars in 2002. That represents an improvement of 5 x 106
(= approximately 222) in 34 years. This represents 22
doublings in 34 years, or about 1.6 years per doubling. Again,
the trend has been very smooth in intervening years.7
Click for larger version
Keep in mind that unlike Gertrude Stein's roses, it is not the
case that a transistor is a transistor. Because transistors have
been getting steadily smaller (at an exponential rate), they have
been getting faster, so this factor brings down the doubling time
for price-performance even further. And there are other levels
of innovation that also improve price-performance.
The available data also supports exponential growth in volumes.
The number of transistors shipped, according to Instat/MDR, went
from 2 x 109 in 1968 to just under 1018 in
2002, or an increase of about 4 x 108 (= 229)
in 34 years. This represents a doubling time of 1.1 years.8 Again, this ignores other levels of improvement.
Click for larger version
Now let's factor in the speed improvement. Interestingly, Tuomi
provides us with this exponential trend in his paper9:
Tuomi's Figure 4: Desktop computer processor
speed.
Source: Berndt et al., 2000, Table 1.
It is difficult to see the exponential trend in Tuomi's
linear chart, so I provide here our own logarithmic chart of microprocessor
clock speed, which shows both the historical data and the ITRS road
map10:
Click for larger version
With a speed improvement of approximately 103 in 34
years (1968 to 2002), the cost per transistor cycle decreased by
a factor of 5 x 109 (= 232), resulting in
a doubling time of just over 12 months.11
Even this analysis takes into consideration only semiconductor density
and process improvements, and does not take into consideration improvements
at higher levels such as processor design (for example, pipelining,
parallel instruction execution, and other innovations).
Click for larger version
The theoretical total number of transistor cycles in the world
increased by a factor of 4 x 1011 (= 239)
in 34 years, resulting in a doubling time of only 10.4 months.
One could go on for many pages with such analyses, measuring many
different dependent measures, and citing data from many sources,
all of which show clear exponential growth. Tuomi's myopic finding
that there is no exponential growth in the semiconductor industry
is notable, and I admire his tenacity in attempting to prove that
the world of information technology is flat (i.e., linear).
One reason technology improves exponentially is that we seek to
improve quantifiable measures by multiples rather than by linear
increments. About a half century ago, Dr. An Wang and his engineers
struggled to add an increment of a thousand bits to his (iron-core-based)
RAM storage. Do engineers struggle to add a thousand bits to a
memory design today? Or a million bits? Design goals today are
more likely to be measured in billions of bits. Goals are always
set in a multiplicative relation to the current standard.
Another reason that technology improves exponentially is that we
use the (more) powerful tools of one generation of technology to
create the next. Early computers were designed pen-on-paper and
wired with individual wires and screwdrivers. Today, a chip or
computer designer specifies formulae and high-level parameters in
a high-level language, and many layers of intermediate design are
automatically computed by powerful computer-assisted-design software
systems.
For these and related reasons, we see exponential growth not only
in memory and computational price-performance, but across the board
in information-related technologies. For over two decades, I have
been studying key measures of capacity and price-performance in
a wide variety of such technologies. The data clearly shows exponential
growth that goes far beyond Moore's Law or computation. We see
exponential growth in a broad variety of measures of the capacity
and price-performance of information technologies. To provide just
a few examples, consider the price-performance of magnetic-disk
memory density, which is a phenomenon distinct from semiconductors12:
The Internet13:
Click for larger version
Brain scanning14:
Biological technologies such as DNA sequencing15:
Click for larger version
We also see exponential growth in varied measures of human knowledge,
and even in the key feature sizes of technology, both electronic
and mechanical.16
Tuomi himself adds to our extensive list of examples of exponential
growth in information when he writes, "According to Price (1986),
the number of scientific journals has doubled about every 15 years
since 1750, the number of 'important discoveries' has doubled every
20 years, and the number of U.S. engineers about every 10 years."17
I do agree, however, that for many applications, exponential growth
of a capability (such as memory size or processor speed) does not
necessarily translate into exponential growth in utility. For many
functions, it requires exponential growth in capability to obtain
linear gains in functionality. It requires, for example, exponential
gains in computing to obtain linear gains in chess ratings. Similarly,
we see linear gains in the accuracy of pattern recognition algorithms
(for example, speech recognition) with exponential gains in processor
speed and memory capacity. However, for inherently exponential
problems, linear gains in functionality and performance are very
powerful and sufficient to obtain profound benefits.
Tuomi writes that "Exponential growth . . . is very uncommon in
real world [sic]. It usually ends when it starts to matter."18
It is clear, however, that the information industry (in all of its
manifestations) has indeed begun to matter. Moreover, Tuomi provides
no basis to conclude that exponential growth in computing has ended
or is about to end.
When we are unable to continue to shrink two-dimensional integrated
circuits, we will build three-dimensional circuits. Note that this
will not be the first paradigm shift in computing because Moore's
Law itself represented not the first but the fifth paradigm to provide
exponential growth to computing. Prior to flat integrated circuits,
we had electro-mechanical calculators, relay-based computing vacuum
tubes, and then discrete transistors. Even though the semiconductor
industry road map19
indicates that we have more than a dozen years left to obtain exponential
growth through two-dimensional circuits, there has been enormous
progress in recent years in developing early prototypes of three-dimensional
circuits.
Based on our current understanding of the physics of computing,
the inherent limits to exponential growth of computation and communication
are extremely high (that is, the minimum matter and energy required
to compute a bit or transmit a bit is extremely low).20
One of the most promising is to create general-purpose electronics
using nanotubes, which are hexagonal arrays of carbon atoms. This
approach has shown considerable promise in experiments. When fully
developed, nanotube-based circuitry has the potential to be many
orders of magnitude more powerful than flat integrated circuits.
Even nanotubes do not approach the fundamental limits of computing,
based on our current understanding of the physics of computation.
In Tuomi's review of the industry's history, he notes that on several
occasions the industry just happened to be "saved" by special circumstances,
for example, the emergence of the calculator and memory chip markets
in 1965-68.21 Tuomi assumes that the industry was just lucky
that the invention of these two product categories came at the right
time. He writes that in general, "semiconductor technology has
evolved during the last four decades under very special economic
conditions."22
But the introduction of new product categories made feasible by
the greater price-performance of each new generation of semiconductor
technology is inherently part of the process. More powerful chips,
which have been occurring on a very predictable basis, lead to new
product categories, which in turn lead to greater volumes.
The pace of this type of innovation has increased in recent years
with the rapid introduction of new types of digital products. An
inherent aspect of progress in information-based technologies is
new paradigms on every level. Often, old problems are not solved
directly, but rather are circumvented by the introduction of new
paradigms, new applications, and new markets. But to Tuomi, the
50 years of exponential growth attributable to integrated chips
(preceded by 50 years of exponential growth from pre-chip technologies)
is all a temporary aberration.
It is important to point out that an evolutionary process whether
of technology or biology is always a matter of special circumstances.
However, there are always special circumstances. Whatever it was
that hit the Earth that resulted in the demise of the dinosaurs
was a special circumstance, one that had profound implications for
all species at that time. But the progression of biological evolution
was not dependent on that event just happening. In general, evolutionary
events happen in "special" ecological niches that are inherently
delicate and bounded by distinctive circumstances.
The "special circumstances" that Tuomi refers to in the semiconductor
industry have kept Moore's Law going for half a century, and counting.
The acceleration of the price-performance of computation goes back
at least a century. Special circumstances are part of the evolutionary
process not a reason to overlook its exponential progression.
As Gilda Radner used to say on Saturday Night Live, "it's always
something" meaning there is always something special about current
circumstances.
Tuomi's analysis is filled with strained analyses that stretch
the data to make his contrarian points.
Consider his hand-drawn trend lines on the following graph23:
Tuomi's Figure 3: Number of transistors on
Intel microprocessors
Tuomi has drawn his chart in a misleading way. For example, it
suddenly jumps up at year 21, yet this improvement is not taken
into consideration. There are only two outlier points, both around
years 20 and 21 (the "x" below the right point of the middle line,
and the left most point of the right most line). If one draws a
trend line through all of the points, leaving out these two outliers
(which, in any event, cancel each other out), one gets a relatively
smooth exponential chart. See my previous chart on the number of
transistors in Intel microprocessors. Note that both Tuomi's and
my chart leave out the issue of transistor speed and the effect
of many design innovations.
Tuomi includes less powerful processors at various points in time
that skew the curve. There are always less-powerful versions of
processors offered for special markets. The appropriate microprocessor
to include at each point in time is the one providing the optimal
performance. It is also worth pointing out that the number of transistors
in a microprocessor is not the most relevant variable to measure.
We are more concerned with the functionality per unit cost.
As noted previously, at some point, there will be an optimal number
of transistors to perform the functions of a single processor.
At that point, we won't be interested in increasing the number of
transistors in a microprocessor, but we will continue to be interested
in improving price-performance. Above, I provided a properly constructed
chart on transistors in Intel processors.
If we measure what is really important (overall processor performance),
we need to consider speed improvements, among other factors. Tuomi
himself provides evidence of the exponential speed improvement in
his figure 4 above. Taking speed as well as design innovations
into account, we get a doubling time of about 1.8 years for overall
processor performance.24 This does not include the issue of word length,
which has been increasing during this period. Including this factor
would bring down the doubling time further.
Click for larger version
Remarkably, Tuomi prints a similar chart and concludes
that "As can be seen from Figure 5, MIPS ratings of Intel processor
have not increased exponentially in time."25
Tuomi's Figure 5: Processor performance in
millions of instructions per second (MIPS) for Intel processors,
1971-1995.
His hand-drawn trend lines (on a logarithmic chart) show exponential
growth, with the trend lines jumping up (meaning increased values)
at two points. Each straight line on Tuomi's logarithmic chart
is an exponential, but as one goes across the chart (from left to
right), each successive straight line (representing exponential
growth during that time period) is at an even higher level.
How he can conclude that "this shows no exponential growth" is
not explained.
Tuomi cites the following chart26
to make a point about the life cycle of a particular generation
of chip:
Tuomi's Figure 1: Prices and
Quantities of 16-kilobit DRAM chips. Source: Grimm, 1998
Tuomi makes the point that one can obtain misleading trends by
taking price points at different times in the life cycles of different
chips. But this criticism is not valid for any of the charts I
have presented, nor those cited from other industry sources. The
chart that I provided above for average cost per transistor is exactly
that the average cost for that year. In charts involving different
types of chips, prices at the point of production are consistently
used. There has been no attempt to compare one point in the life
cycle of one chip to a different point in the life cycle of another
chip.
However, let's take a look at what happens if we examine the entire
life cycle of multiple generations of semiconductor technology27:
Click for larger version
In this logarithmic chart, we can see the life cycle of each generation,
and the overall exponential trend in the improvement of price-performance
remains clearly evident.
Tuomi spends a lot of time in both papers talking about the "hedonic"
model for economic value of various features and "quality" improvements
such as increased memory or increased speed. He writes:
"
if a 100 MHz PC costs today 500 dollars
more than a 60 MHz PC, we might assume that if a 100 MHz PC costs
today as much as a 60 MHz PC a year ago, technical advance has been
worth 500 dollars."28
The hedonic model has little validity. Current software may only
make sense for the mainstream specifications, so purchasers would
not be willing to pay very much for more memory than they need for
the applications they have or intend to use. However, at a later
time, when the more sophisticated applications available require
more memory, they would be willing to pay for this extra memory,
and in fact would not want the computer if it didn't provide the
memory (or other capabilities) necessary to run these applications.
Furthermore, certain variations in specifications may appeal only
to small niche markets. All of these factors distort this hedonic
model methodology.
However, despite these methodological concerns, Tuomi himself cites
numerous examples of exponential growth in price-performance based
on quality-adjusted prices. He writes:
"The classic study of quality corrected prices in computing
is by Chow (1967), who analyzed mainframe rental prices in the 1960s.
According to Chow, quality-adjusted prices fell at an average annual
growth rate (AAGR) of about -21 percent during the 1960-1965 period.
Cole et al. (1986) studied the price declines of different computer
components and found that over the 1972-1984 period, the AAGR for
computer processors was -19.2 percent using the hedonic prices.
. . .Cartwright (1986), in turn, reported an AAGR of -13.8 percent
from 1972 to 1984. According to Gordon (1989), quality adjusted
mainframe prices fell 22 percent annually from 1951 to 1984."29
These are all exponential improvements cited by Tuomi. It should
also be noted that during this time frame, mainframes started out
as the best value, but were no longer remotely close to the best
value by the end of the time period. Mainframes maintained artificially
high prices to locked-in customers (who eventually escaped the lock-in
to minicomputers and then personal computers). Nonetheless, even
just considering mainframes, and an insufficient "quality adjustment"
methodology, it still shows exponential improvement in price-performance.
Tuomi continues:
"Triplett (1989) summarized earlier hedonic studies
on mainframe computer prices and reported a 'best-practice' quality-adjusted
price decline of -27 percent over the 1953-1972 time period. Gordon
(1990) then extended his earlier analysis to personal computers
and reported 30 percent annual declines from 1981 to 1987. Berndt
and Griliches (1990) collected a large sample of data on personal
computers and reported 28 percent annual decreases from 1982 to
1988."
Note that a 30% decline each year = 51% decline (i.e., doubling
of price-performance) in 2 years. 28% each year = 48.2% decline
in 2 years, all examples of exponential growth.
Tuomi provides even further evidence of exponential improvement:
"Grimm has also calculated price indexes for microprocessors
using the same methodology. For microprocessors the decline in price
indexes has been considerably faster than for memory chips. During
the 1985-1996 period, quality adjusted microprocessor prices dropped
at an average annual rate of 35 percent."
Note that an annual improvement of 35 percent is a doubling time
(of price-performance) of less than 24 months. Also, the quality
adjustment methodology, as I noted earlier, understates the values
for the reasons I cited above. Tuomi's conclusion is again to state
the "the price decreases have not followed an exponential trend."
This conclusion is not consistent with the evidence that Tuomi provides
in his own papers.
Tuomi consistently miscalculates these doubling times. For example,
he writes:
"on average prices per unit of memory have declined
32 percent per year during the 1978 2000 period. This corresponds
to a 30 month doubling time."30
If prices drop 32 percent in one year, a price of $1 would
be $0.68 after one year and $0.46 after two years (i.e., falling
to less than half in 24 months). A 32 percent decline in price
per year corresponds to a doubling time of under 22 months, not
30 months. He makes this mistake repeatedly, so Tuomi's stated
doubling times cannot be relied upon. Regardless of whether the
doubling time is calculated correctly or not, this is one of many
pieces of evidence cited by Tuomi himself of exponential improvement.
In Tuomi's paper on my law of accelerating returns, "Kurzweil,
Moore, and Accelerating Change31,"
he describes my thesis as leading "to an apparently infinite speed
of change." I do want to clarify that exponential growth, even
double exponential growth, does not lead to infinite rates of change.
It nonetheless will lead to greatly transforming rates of change.
Repeatedly, Tuomi cites Moore's change in description of what has
become known as Moore's Law from his 1965 paper, in which he cited
a doubling time of transistors per dollar of one year, to his revised
estimate in 1975 of two years. Tuomi describes this as Moore noting
"that the speed of technical change was slowing down." This is
a mischaracterization. Moore simply corrected his earlier estimate
to a more accurate one (one that has, incidentally, been conservative).
He was not saying that it had been one year and was now becoming
two years. He was saying that his earlier one-year estimate had
been incorrect, and that it had been two years and would remain
so.
As I mentioned earlier, when presented with the "forest" of a trend,
Tuomi often responds with a comment about a missing branch of a
tree. For example, in response to my chart on a century of double
exponential growth in computing:
Tuomi responds that "Ceruzzi (1998:71,74) gives $1.6 to
about $2 million as the price of a full IBM 7090 installation. Kurzweil
uses $3 million. Kurzweil has also moved Babbage's Analytical Engine
about half a century in time, with the explanation that it probably
could have been built in 1900. Other authors have argued the machine
could have been built using available manufacturing capabilities."
I would argue with both of Tuomi's assertions, but even if one
removes these two points, it hardly makes a dent in this forest
of a trend.
My team of researchers has been adding additional points to this
trend that corroborate this double-exponential trend. Note that
a straight line on a logarithmic graph represents exponential growth,
and that the exponential trend here is itself exponential it took
three years to double the price-performance of computing at the
beginning of the twentieth century, two years in the middle, and
it is now doubling approximately every one year.
Hans Moravec's analysis32,
which includes additional points from my own chart, also shows the
same double-exponential trend:
Click for larger version
Tuomi also writes that "Historical data also reveals that the early
computers rarely were working at their theoretical speeds." This
point only strengthens the observation that later computers were
more powerful.
Perhaps the most convoluted argument that Tuomi presents is his
discussion of the alleged lack of increased resources to the semiconductor
industry. He writes "Technological developments in the semiconductor
industry are generally viewed as the drivers of progress in computing.
According to Kurzweil's hypothesis, one would expect semiconductor
industry to enjoy increasing positive returns that would speed up
technical developments in the industry. Indeed, in Kurzweil's model,
the rapid technical developments would be caused by the increase
in resources available for developers."
Remarkably, Tuomi states that there have been no "accelerating
increases in its resources." Yet he cites a report from the World
Semiconductor Trade Statistics (WSTS) that "the average year-to-year
change in semiconductor shipment value during the 1958 2002 period
is 18 percent." This, of course, is exponential growth, so how
does Tuomi justify his conclusion that I am incorrect in my assessment
that the computer and information industries (which includes the
semiconductor industry) have benefited from increased resources?
Tuomi provides this chart33:
Click for larger version
He takes the growth rate of the semiconductor industry and subtracts
the growth rate of the U.S. GDP. This is a dubious proposition
because the growth rate of the GDP is fueled specifically by technological
innovation, particularly in information technologies. So we are
subtracting from the growth rate of the semiconductor industry the
growth rate of the economy. Yet it is the semiconductor and information
technology industries that are primary contributors to the growth
of the economy.
The result is nonetheless positive, which Tuomi calculates as averaging
10.8 percent annual growth (over the GDP growth). However, he then
takes the derivative (slope) of this curve and notes that it is
negative.
From this, he concludes that the semiconductor industry has not
enjoyed increased resources. Yet, the industry has grown on average
by 18 percent according to Tuomi's own analysis, and this growth
rate exceeds that of the overall economy to which it contributes.
The appropriate conclusion of the negative slope in this complex
graph is that the growth rate of the economy is catching up to the
growth rate of the semiconductor industry. The reason for that
is that information technology in general is becoming increasingly
pervasive and influential. Information technology itself has gone
from 4.2% of the GDP in 1977 to 8.2% in 1998, with the growth rate
recently accelerating.34
Click for larger version
Moreover, information technology is increasingly influential on
all aspects of the economy. Even those industries that are not
explicitly "information technology" are nonetheless deeply influenced
by it. We are rapidly moving towards an era in which the dominant
portion of the value of most products is represented by their information
content. Thus the overall economy is slowly catching up to the
rapid growth rates of information-related industries such as the
semiconductor industry, specifically because of the effect of these
industries.
The bottom line is that resources have increased exponentially
in the information technology industries, including the semiconductor
industry, and this rate of growth is not slowing down. Moreover,
this is the less important part of the story. The more important
issue is not merely the increase in dollars, but the very rapid
exponential growth of what each dollar buys.
Both hardware and software have increased enormously in power.
Today, a semiconductor engineer sits at a powerful computer assisted
design station and writes chip specifications in a high-level language.
Many layers of intermediate design, up to and including actual chip
layouts, are then computed automatically. Compare that to early
semiconductor designers who actually blocked out each cell with
ink on paper. Or compare that to the early computer designers who
wrote out their designs by pen and then built the computers with
individual components, wires and screwdrivers.
Tuomi cites the following graph to argue that computers and software
investments have not been growing exponentially35:
Click for larger version
First of all, the data on figure 2 above matches a slow exponential
more closely than a straight line, which does not match very well.
The data starts under the line and ends up over the line.
More importantly, this graph is not plotting the actual computer
and software investments, but rather expressing them as a percentage
of private fixed investment, which is itself growing exponentially,
reflecting the growth of the IT sector as a percentage of the GDP.
Tuomi writes that ". . .an exponential trend defines a technical
trajectory that is independent of any external factors. Moore's
Law, in its original form, is basically such a claim. Its exponential
form implies that. . .developments in integrated circuits are effectively
independent of economic, organizational, social, or any other forces."36
Tuomi here is misunderstanding the nature of exponential growth
in information technology. The development of semiconductors and
related computer technologies is not taking place in a vacuum.
External factors are very much involved. This is a classical evolutionary
process taking place in a competitive environment. If there were
no economic value to increased capacities, they would not be developed.
Greater capacities and price-performance lead to new capabilities
and applications, which in turn result in increased demand. Moreover,
the more powerful tools from one generation of technology create
the next more powerful generation.
Tuomi's argument becomes particularly strained when he discusses
the purported benefits of analog computing. He writes, "Many mathematical
problems that require an infinite number of algorithmic computations
can be solved by intelligent humans and by non-algorithmic calculating
machines. A classical technical method of doing this has been to
use analog computers. Indeed, in many classes of mathematical problems
the computational power of an analog computer is infinitely greater
than the computation power of conventional digital computers."
The above statements are illogical. "Humans and non-algorithmic
calculating machines" are clearly not able to solve mathematical
problems that "require an infinite number of algorithmic computations."
Moreover, the use of an analog computer certainly does not allow
one to accomplish this.
It is also completely unjustified to say that an analog computer
"is infinitely greater than the computation power of conventional
digital computers." This conclusion derives from the naïve notion
that digital computers can only deal with "on" and "off," and not
with shades of gray in between. By using floating point numbers,
digital computers can represent fractional values to any desired
precision. In fact, digital computers are much more precise than
analog computers in doing this.
Prior to World War II, analog computers were popular, and digital
computers required the "digital" modifier to distinguish them.
But analog computers are so unpopular today that we no longer are
required to use the word "digital" before "computer." Although
an analog computer can represent a fractional value, the accuracy
of analog components is relatively low and unpredictable. With
a digital computer's floating point numbers, the accuracy is known
from the number of bits in the floating point representation.
If desired, one could use thousands of bits in each floating point
number (the algorithms for doing this are well understood), which
would provide accuracy far exceeding any conceivable analog process.
Of course, for most practical applications, 32-bit or 64-bit floating
point numbers are quite sufficient, and exceed the accuracy of existing
analog computers.
There is an engineering argument that for some applications, such
as precisely modeling the nonlinear aspects of human neurons, using
transistors in their native analog mode is more efficient. California
Institute of Technology Professor Carver Mead has pioneered this
approach to doing neuromorphic modeling. There are counter-arguments
to this: such analog chips are difficult to design and are not programmable.
But regardless of how one settles this particular design issue,
Tuomi's statements about analog computers appear to have no basis.
In conclusion, every time I open the morning paper (which I now
usually read online) and look at the specifications and prices in
the ads for the latest digital phones, digital cameras, portable
electronic games, MP3 players, digital TVs, notebooks, tablets,
and pocket computers, among an increasingly diverse set of new product
categories, I am reminded of the obvious exponential growth in price-performance
that Tuomi insists on denying.
Further Detailed Response
I provide here a detailed response to specific assertions in Tuomi's
thesis. I encourage the reader to read Tuomi's papers in full to
obtain the full context of Tuomi's statements.
Responses to Ilkka Tuomi's
"The Lives and Death of Moore's Law"37
Tuomi: Technical considerations of optimal chip manufacturing
costs have been expanded to processor performance, economics of
computing, and social development. It is therefore useful to review
the various interpretations of Moore's Law and empirical evidence
that could support them.
Such an analysis reveals that semiconductor technology has evolved
during the last four decades under very special economic conditions.
Kurzweil: Every paradigm has special conditions. Evolutionary
change in either biology or technology always derives from finely
tuned conditions and operates at the edge of survival (of a species
or a product line).
Tuomi: Several observers have . . . . speculated about the possibility
of "the end of Moore's Law." Often these speculations
have concluded by noting that Moore's Law will probably be valid
for at least "a few more generations of technology," or
about a decade. An important example is the International Technology
Roadmap for Semiconductors (ITRS), which now extends to 2016. This
roadmap is generated by a global group of experts and represents
their consensus. . . . it notes that within the next 10-15 years
"most of the known technological capabilities will approach
or have reached their limits."
Kurzweil: These well-publicized limits of Moore's Law pertain to
flat two-dimensional circuits only. Sometime during the second
decade of this century, key feature sizes will be a small number
of atoms in width, and we won't be able to shrink them further.
At these scales, these circuits are vastly more efficient than the
cumbersome electrochemical signaling used in mammalian interneuronal
connections, but only in 2-D. We live in a three-dimensional world,
and it is clear that we will move into the third dimension. The
research accomplishments underlying three-dimensional molecular
computing are escalating rapidly, and are ahead of comparable points
in history prior to other paradigm shifts. The entire paradigm
of Moore's Law (flat integrated circuits) was not the first but
the fifth paradigm to provide exponential growth to computing
each time it became clear that a paradigm would end, research would
intensify on the next paradigm.
Tuomi: Speculations on the extended lifetime of Moore's Law
are therefore often centered on quantum computing, bio-computing,
DNA computers, and other theoretically possible information processing
mechanisms.
Kurzweil: This is the wrong list. Quantum computing, bio-computing
and DNA computers, if perfected, would be special-purpose devices.
Although prodigious on certain classes of problems, they are not
suitable for general-purpose computing. Quantum computing can in
theory try every combination of qubit value simultaneously. So
for the class of problems in which a solution can be easily tested,
such as finding the factors of large numbers to break encryption
codes, it is a great technology. But it provides no speed improvement
for most conventional computing problems. The primary focus for
the sixth paradigm of computing (after electromechanical, relay-based,
vacuum-tubes, discrete transistors, and integrated circuits) is
three-dimensional molecular computing. I have always favored nanotube-based
designs, and these in fact have obtained the most advances in recent
research.
Tuomi: The fundamental assumption was that the total manufacturing
costs are practically independent of the complexity of the chips.
For this to be the case, the engineering and design costs had to
be so small that they could be neglected. Indeed, Moore noted that
the costs of integrated circuits were totally dominated by packaging
costs. In other words, the costs of silicon was fixed and knowledge
was free and the only limiting factor in manufacturing costs was
the rapidly increasing waste created by deteriorating yields. Moore's
discussion did not explicitly take into account investment costs.
Kurzweil: It is true that engineering of each new generation of
chips has become more complex, but there have been countervailing
trends that more than offset this. First, CAD sophistication (and
the computers to run CAD software on) has substantially increased,
allowing increasingly sophisticated chips to be developed in comparable
time frames. Also, the number of chips produced in each generation
has increased at an exponential rate, allowing development costs
to be amortized over an increasingly large volume.
Tuomi: From an economic point of view, Moore's Law was a rather
fascinating law. It implied that the development of integrated circuits
was completely determined by manufacturing costs. Moore's Law, therefore,
defines a completely new economy. In this economy, demand is infinite.
Kurzweil: Infinite? This is clearly an oversimplification. Nonetheless,
demand has kept pace with continued exponential gains in memory
size and computer capabilities, as evidenced by the exponential
growth of the semiconductor industry (which Tuomi himself describes
as being 18 percent per year) and the overall information technology
industry. Below, Tuomi cites some examples of this as accidents
that just happened to save the industry at various times. The reality
is that the opening of new markets is inherently part of the process.
There are many applications today that are waiting for the communication
speeds, memory, and computational capacities of future years (such
as ubiquitous full-immersion, visual-auditory virtual reality for
business and personal encounters, augmented reality and telepresence
applications, and many others).
Tuomi: The essence of Moore's argument had been that it was
becoming possible to manufacture increasingly complex integrated
circuits and that the price per component was dropping radically.
The limiting factor would be efficient amortization of design investments.
This could be done in two basic ways: either by making high volumes
of single function or by making designs that could be used for many
different chips. The first path led to Intel's focus on memory chips
and the latter, a couple of years later, to microprocessors.
Kurzweil: Also by increases in chip volume created through new
applications that result from the greater capabilities of each new
generation of chip technology.
Tuomi: In his presentation, Moore analyzed the different causes
of the exponential development. First, the physical size of the
chips had been growing approximately exponentially. In 1975, chip
sizes of the most complex chips were about 20 times larger than
in 1959. Second, the miniaturization of component dimensions had
also evolved at roughly exponential pace. This miniaturization had
led to about 32-fold increase in component density in 15 years.
The combination of increased chip size and component miniaturization
therefore seemed to explain about 640-fold increase in the number
of components. According to Moore's prediction, however, in 1975
chips were supposed to contain more than 640 components. The remaining
100-fold increase Moore associated with "circuit and device
cleverness". New technology, such as better isolation of components
and innovations in circuit layouts had made it possible to pack
more components closer to each other (Moore, 1975).
Kurzweil: Miniaturization of component dimensions results not only
in more components per unit size, but also in faster circuits, since
the electrons have less distance to travel. In addition, there
is innovation on every level in both hardware and software. Beyond
just packing more and faster circuitry onto each square millimeter,
there have been many innovations in processor design, such as pipelining,
register caches, parallel processing, more powerful instruction
sets, etc.
Tuomi: Moore revised his original growth rate estimate and proposed
that by the end of the decade, the number of components on the most
complex chips would double about every two years. Soon after, this
prediction became known as "Moore's Law." According to
Moore, the name was coined by Carver Mead (Yang, 2000).
Kurzweil: This was a revision, not an observation of the data changing.
Tuomi: In 1975, Moore implicitly changed the meaning of Moore's
Law. As he had done ten years before, he was still counting the
number of components on semiconductor chips. Instead of focusing
on optimal cost circuits, however, he now mapped the evolution of
maximum complexity of existing chips. Indeed, in an article written
a few years later, the famous growth curve is explicitly called
"Moore's Law limit" (Moore, 1979). At that point the growth
estimate is presented as the maximum complexity achievable by technology.
In Moore's 1979 paper, which shows a picture with component counts
of Intel chips manufactured in 1977 and 1978, most chips fall one,
two, or even three orders of magnitude below this limit.
Kurzweil: Although Moore showed a chart like this, plotting the
maximum complexity of chip technology at different points in time
is not an appropriate way to measure performance. One has to measure
performance on the most cost- effective implementation of computing
technology at each point in time. So, for example, one would not
just measure mainframe performance, because after minicomputers
became established, mainframes were not the most cost-effective
implementation. The same thing happened to minicomputers when personal
computers became established. These older markets only persisted
because customers were locked into legacy applications, but these
were not the most cost-effective platforms.
Tuomi: . . . .in 1975.. . . Intel introduced the 16-kilobit
CCD, the Intel 2416. In the same year Intel also introduced its
2116-chip, a 16-kilobit dynamic random-access memory (DRAM) chip.
Such a chip would have contained somewhat over 16,384 transistors,
including some control circuitry, and about 16,384 capacitors. Since
the mid-1970s, complexity has been counted based on the number of
transistors. Moore's earlier calculations, however, were based on
the total number of components.
Kurzweil: This is typical of Tuomi nit-picking. The reality is
that regardless of whether one looks at number of components or
number of transistors, there has been clear exponential growth.
Tuomi: Moore presented a new exponential growth curve in his
1979 paper. According to it, the man-hours per month required for
integrated circuit production was also growing exponentially. Moore
went on to note:
"If we assume that the cost in man-hours per month is inflating
at 10 per cent per year (a conservative figure considering the need
for increased computer support, software, etc.), then the costs
double every two years ... This cost can be contrasted with manufacturing
costs, which are largely independent of device complexity. Whereas
manufacturing costs were once dominant and exceeded those of design,
the situation is now reversing, with design costs becoming dominant".
Kurzweil: One has to take into consideration the exponential growth
in volumes that were also taking place.
Tuomi: Moore also noted that the problems that slowed down the
growth of semiconductor complexity in the 1965-1968 period had not
been solved. Engineers were still unable to design and define products
that would have used silicon efficiently. Instead, the industry
was saved by the invention of two product categories where these
problems could be avoided. . . .The calculator was an important
product because it was a relatively simple system. Merely connecting
four integrated circuits (that had about 40 pins) created a calculator.
The interconnection problem, therefore, was tractable. As calculators
were produced in high volumes, the design costs could be justified.
Memory chips, in turn, were easy to design and universal in their
functionality, and therefore also high volume products with low
design costs.
Kurzweil: Tuomi assumes that the industry just happened to be "saved"
by the lucky invention of these two product categories. But the
introduction of new product categories made feasible by the greater
price-performance of each new generation of semiconductor technology
is inherently part of the process. More powerful chips, which have
been occurring on a regular basis, lead to new product categories,
which in turn lead to greater volumes. The pace of this type of
innovation has increased in recent years with the rapid introduction
of new types of digital products. In addition, another inherent
aspect of progress in information-based technologies is new paradigms
on every level. Old problems are often not directly solved they
are circumvented by introducing new paradigms, new applications,
and new markets.
Tuomi: Moore himself has noted:
"I never said 18 months. I said one year, and then two
years ... Moore's Law has been the name given to everything that
changes exponentially. I saw, if Gore invented the Internet, I invented
the exponential" (Yang, 2000). The historically inaccurate
18 months doubling time has been extremely widely used. It is possible
even to find fictive quotes of Moore's 1975 presentation saying:
"The number of transistors per chip will double every 18 months."
Kurzweil: Tuomi is correct that the 18 month figure is incorrect
(for most measures). Moore never said it, and it does not match
the data. Tuomi continues to beat this dead horse repeatedly in
the rest of this paper.
Tuomi: As noted above, Moore never claimed that the number of
components would double every 18 months. The first version, the
doubling of components on a chip every year, would mean that the
number of components would increase 1024-fold per decade. The second
version, doubling every two years, would translate into a much more
modest increase of 32 per decade. In fact, the International Technology
Roadmap for Semiconductors (ITRS, 2001) uses as the basis of its
near-term microprocessor forecasts three-year doubling time. A three-year
doubling time means that the number of transistors on a chip increases
about nine-fold in a decade.
Kurzweil: The ITRS roadmap shows doubling of the number of bits
per DRAM memory chip every two years: 1 Gb in 2003, 2Gb in 2005,
and so on up to 64Gb chips in 2015-2016. That represents a 24-month
doubling time. If we factor in additional improvements, including
faster switching time and anticipated lower chip costs, the doubling
time in price-performance will be less than 24 months.
If one looks only at the reduction in feature size in the ITRS
roadmap for microprocessors, one gets a doubling of capacity per
mm2 in 36 months, but this is consistent with the rate
of reduction of feature size going back to 1965. Despite this,
the doubling time for the number of transistors per microprocessor
has been 24 months, as I cited earlier. The cost per transistor
has been coming down by half every 19 months. And when we factor
in the increases in speed, the cost per transistor cycle has been
coming down by half every 13 months.
It is also important to keep in mind that whereas increasing the
number of bits in a memory chip increases its utility without limit,
there is a limit to the number of transistors that are desirable
in a microprocessor. At a certain level of complexity, we would
rather concentrate on reducing the cost per microprocessor and using
multiple processors than to continue adding complexity to a single
processor. The same consideration does not apply to DRAM. When
all of these factors are considered, the doubling time for price-performance
for microprocessors in the ITRS roadmap is less than 24 months.
Intel's own roadmap is somewhat more aggressive than ITRS.
Tuomi: Over several decades the differences obviously increase
dramatically. During the four decades of validity often claimed
for Moore's Law the difference between one-year and three-year doubling
time means about eight orders of magnitude. In other words, to get
the same number of transistors, the slower growth path would require
us to buy 100 million chips, instead of one. So, although a few
months more or less in the doubling rate might not appear to be
a big deal, actually it is.
Kurzweil: As I pointed at the beginning of my response, there is
no confusion between one-year and three-year doubling times. The
trends have been very consistent and both the ITRS and Intel road
maps project the same rate of exponential growth out through 2016.
Whether one gets a 12 month doubling time or a 36 month doubling
time depends on what is being measured. If one looks at a single
issue such as line width, one gets longer doubling times. If, however,
one considers the multiple levels in which innovation takes place,
the doubling times are closer to 12 months.
Tuomi: As specific chip types usually have a long lifetime during
which the costs and other parameters of the chip change, the ITRS
roadmap differentiates four main life-cycle phases. The first is
the year of demonstration. This is the year when the feasibility
of a specific characteristic, for example the number of transistors
on a single chip, is first demonstrated. The second phase, market
introduction, usually two or three years later, is defined to occur
when the leading manufacturer ships small quantities of engineering
samples. The third phase, production, is defined to occur when the
leading manufacturer starts shipping the chip in volume quantities
and a second manufacturer follows within three months. The lowest
cost phase emerges when the production processes have been optimized
and competition does its work. For example, the 1-gigabit DRAM was
demonstrated in 1997, introduced in 1999, and is expected to be
in volume production in 2003. Similarly, the Intel Itanium processor
was announced in 1994, was originally planned to be on market in
late 1997, but was delayed and became commercially available in
2001. Market researchers currently project that Itanium will garner
less than 10 per cent of the market for server computing in 2007
(Markoff and Lohr, 2002).
Kurzweil: Valid methodologies consider the most cost-effective
form of memory or processor at each point in time. Obviously one
can obtain invalid results by failing to do this. Tuomi makes this
mistake later in this essay by concentrating on mainframe trends
way past the point that mainframes represented the most cost-effective
method of computing. In addition, graphs of processor speeds and
density use the date of production so we can compare consistent
points in development of each device.
Tuomi: Using this data we can fit an exponential growth curve
and see how good the fit is. . . . . According to this simple fit,
there were some five million transistors missing from Pentium II
in 1997, representing about 70 per cent, and some 7.5 million, or
some 18 per cent, too many in the Pentium 4 in 2000. The estimate
for Pentium 4 comes relatively close to its actual value as the
data, indeed, has been used to fit the exponential, and the final
point is heavily weighted. The error would be greater if we were
to use previous points to fit the curve and then predict the number
of transistors of Pentium 4.
Kurzweil: Tuomi concentrates here on variances of the actual curve
(which is clearly exponential and has about a 24 month doubling
time) to a "predicted value." This is irrelevant. It is true that
many observers quote an 18 month doubling time for price-performance.
18 months happens to be approximately correct for the price per
transistor (we get 19 months), but not accurate for the number of
transistors per microprocessor. There seems to be little point
in repeatedly making this point. Tuomi is clearly not demonstrating
a lack of exponential growth.
Tuomi: One problem . . . . is that the clock speed is not directly
related to the amount of information processed. For example, the
original Intel 8088 PC microprocessor took on average 12 clock cycles
to execute a single instruction. Modern microprocessors can execute
three or more instructions per clock cycle.
Kurzweil: The improvements that Tuomi cites only serve to accelerate
improvement further. One could also add increases in word and instruction
sizes (from 4 bit to 8 to 16 to 32 to 64 to 128) and other improvements.
Tuomi: With the understanding that the clock frequency does
not really measure processor performance, one may, however, check
how clock frequency has evolved during the lifetime of microprocessors.
Information on average processor clock speeds has been collected
by Berndt et al. (2000). This is shown in Figure 4 (see above) on
processor speed. The data covers distinctly identified personal
computers that have been marketed and sold in the U.S. Processor
speeds for mobile computers are excluded from Figure 4.
Figure 4 has several interesting characteristics. First,
it should be noted that the data do not directly represent advances
in microprocessor technology. It is based on computers that have
been marketed to end customers. In that sense it does reflect changes
in the actually available processing power. As can be seen from
the Figure, until the end of 1980s the increase in the reported
processor speed was quite modest. During the first decade, processor
speed grew about four-fold and between 1986-1995 somewhat less than
10-fold. In about 1994, the clock speed started to grow much more
rapidly.
Kurzweil: Tuomi's chart 4 (see page 4 above) on processor speed
is an exponential (and represents only one factor contributing to
processor price-performance).
Tuomi: By 1985, then, demand had started to be less than infinite
and the semiconductor industry was not endogenously driven by technology.
In 1982, the increase in MIPS ratings stopped for about three and
half years instead of following an exponential trend.
Kurzweil: This is not true if one looks at Tuomi's own chart (see
Tuomi's figure 5 earlier in this essay). Although he does not place
any points on the chart during 1982-1985, the points starting in
1985 are at an even higher level than would be expected by extrapolating
the 1970-1982 trend line to 1985.
Tuomi: During the last decades, computer clock frequency and
the number of instructions per second have become very inaccurate
indicators of processor power. Since the Intel 80286 processors
shipped in 1982, microprocessors have utilized parallel processing
in many alternative forms. By parallelism, more operations can be
accomplished within a time unit. For example, the processor can
be loaded with instructions that contain several operations, it
can have several execution units that process multiple instructions
within one cycle, or the processing of operations can be started
before the previous operations have finished. All these forms of
parallelism have commonly been used since the mid-1980s.
Kurzweil: This is one of many innovations.
Tuomi: Moreover, since the 1990s, processor architectures have
increasingly relied on program compilers that detect and optimize
parallelism in the source code programs. Indeed, the innovations
in compiler technology have been a main driver in processing power
improvements.
Kurzweil: This is an unjustified oversimplification. It is only
one of many factors.
Tuomi: Computing power is rarely determined by the capabilities
of microprocessors. Usually, the microprocessor is connected to
external memory and input and output devices with links that are
an order of magnitude slower than connections within the chip.
Kurzweil: The capabilities of microprocessors are certainly important
as one driving force. Communication busses have always been about
an order of magnitude slower than communication within a chip.
However, all of the various systems in a computer, such as the hard
disk, the communication busses, and other devices, have benefited
from exponential improvements in capability.
Tuomi: The attempt to develop measurement systems for computer
processing power have made it clear that the definition of computing
power depends on the tasks for which the computer is used. Therefore
there is no well-defined criterion or data for arguing that computer
power would have increased exponentially. On the contrary, it has
frequently been argued that most of the increase in computer capabilities
has been consumed by software. This is often formulated as Wirths
law: "Software gets slower faster than hardware gets faster".
Kurzweil: Try going back and using old software to do common contemporary
tasks. We quickly get used to, and rely on, new features and capabilities.
Tuomi: Clearly, there have been huge qualitative changes in
desktop computers during this time. The problem, then, is how to
take them into account.
One approach is to create so-called matched-model price indexes.
It is possible to measure price changes of a given computer type
across several years and deduce from this the actual price change.
So, instead of looking yearly changes in the list price of desktop
computers, .. . we can look how the price for a given PC configuration
has changed.
Kurzweil: This is not appropriate because a given model of computer
does not necessarily remain the best value model.
Tuomi: A complete personal computer contains several different
types of chips and other components, such as hard disk drives, CR-ROM
drives, a keyboard, and a displays. Price changes in PC, therefore,
reflect quality changes in several different types of technologies.
The hedonic estimation models, however, tend to break down when
new components and functionality are added to computers. When notebook
computers started to become important towards the end of the 1980s,
the different existing technical characteristics became revalued.
For example, more memory perhaps meant progress for desktop users
but for notebook users it implied shorter battery lifetime or the
need to stay close to the power plug when using the computer.
Kurzweil: Battery life for a notebook computer has not decreased.
Fuel cells are on the way, with dramatically improved battery (fuel
cell) life. NEC is introducing fuel-cell-powered notebooks in 2004.
Tuomi: . . . .recent growth may reflect increase in cost-adjusted
performance. For example, architectural changes in microprocessors
during the second half of the 1990s moved much of the external and
expensive cache memory onto the processor chip. On the other hand,
the rapid improvements in average PCs sold might also reflect, for
example, availability of consumer credit and funding for information
technology intensive firms.
Kurzweil: This reflects the increase in the number of chips that
have been produced, which represents another exponential trend.
Tuomi: Price changes, of course, reflect market competition,
imbalances in supply and demand, technical change, and new markets
that open as new uses are found for technology. These have very
little to do with the original formulations of Moore's Law. Yet,
one may ask whether the current economic evidence supports the claim
the cost of computing halves every 18 months.
Kurzweil: Tuomi is really stuck on beating this dead horse. The
doubling time (of price-performance or other measurement) depends
entirely on what is being measured. Some in fact are 18 months,
others range from under 12 months to 36 months. The 36 month categories,
however, do not reflect price-performance.
Tuomi: The change in the average values as well as the yearly
fluctuations show that the price decreases have not followed an
exponential trend. The great differences between the results of
the different modeling exercises show that we do not know how quality-adjusted
computer prices should be measured or how they have changed during
the last decades.
Kurzweil: Tuomi's statement, "the price decreases have not followed
an exponential trend," is a remarkable conclusion. His own paper
provides myriads of exponential trends. This conclusion defies
common sense and ignores reams of data that can be looked at in
many different ways, all of which show exponential trends in price-performance,
and other measures of capability.
Tuomi: In the previous sections we have reviewed the original
formulations of Moore's Law and its revisions. We found that Moore
changed his interpretations of Moore's Law during the 1960s and
1970s, and that its subsequent extensions have added qualitatively
new and important aspects to it. Whereas the original formulations
of Moore's Law focused on counting components on integrated circuits,
its extensions made claims of exponential increase in processing
power and exponentially dropping quality-adjusted prices of computing.
We reviewed the available empirical evidence for these different
versions of Moore's Law and found that they have little empirical
support. Semiconductor technology has not developed according to
Moore's Law. The claims that future developments in semiconductors,
computer technology, or information processing would be determined
by the continuation of Moore's Law are, therefore, obviously invalid.
Kurzweil: The above statements only make sense if one interprets
Moore's Law as strictly being the 18 month statement. Tuomi is
correct that the 18 month version that is often quoted is not correct
but to imply that there is no exponential trend in computing and
semiconductors has no validity.
Tuomi: Here, of course, the industry dynamics play an important
role. For example, computers require software. One of the important
drivers for buying increasingly powerful computing equipment has
been that new versions of operating system and application software
have typically demanded more processing power. Although it seems
clear that today personal computers are much more functional than
twenty years ago, it is not clear how much more functional they
are.
Kurzweil: For many applications, linear improvement requires exponential
gains. For example, we need exponential gains in computing power
to get linear gains in chess scores. This assumes we hold the software
constant. Recent progress in the software of terminal-leaf evaluation
in the minimax algorithm shows that improvements can be gained from
software alone. However, linear progress in what are inherently
exponential problems is very powerful.
Tuomi: The regular doubling and exponential growth that underlies
the different versions of Moore's Law implies a very unique claim.
It fundamentally says that the described phenomenon grows purely
based on its internal characteristics. Exponential growth means
that after the growth speed is set, the future unfolds based on
nothing but the current state of the system. Contrary to what some
commentators of Moore's Law have claimed, exponential growth is
not uncommon. When we put money on a fixed interest rate account,
and reinvest the returns, it will grow exponentially. In this sense,
a bank account is a prototype of self-determined endogenous growth.
Exponential growth, however, is very uncommon in real world. It
usually ends when it starts to matter.
Kurzweil: Tuomi provides no basis to conclude that exponential
growth in computing has ended or is about to end. As mentioned
earlier, the inherent limits to exponential growth of computation
and communication are extremely high (that is, the minimum matter
and energy required to compute a bit or transmit a bit is extremely
low).
Tuomi: During its history, the semiconductor industry has several
times hit the speed limit. First it was bailed out by the digital
clock and calculator industry, then by mini and mainframe computer
industry. In the mid-1980s, just when no one seemed to be able to
make a profit, the IBM PC and Microsoft saved the day.
Kurzweil: Bailed out? This is the inherent process of innovation
powering these exponential trends. The number of such "saves" (in
Tuomi's terminology) is increasing. We recently have cell phones,
digital cameras, PDAs, portable game machines, MP3 players, pocket
computers, and many other new categories.
Tuomi: It is . . . . no surprise that semiconductor industry
has not actually followed an exponential growth trend.
Kurzweil: This is a remarkable conclusion that does not follow
even from his own reasoning. His own paper is filled with exponential
trends, even if most are not 18 month doubling times.
Tuomi: As the size and importance of computer and information
processing technologies now is becoming more than a couple of percents
of national economies, it can be predicted that the endogenous growth
in this industry cluster is about to end. The imbalance between
supply and demand shifts and the social basis of demand makes itself
increasingly visible. The open source movement, for example, effectively
disconnects the economics of operating systems from the economics
of semiconductor manufacturing, thus splitting the industry cluster
in half.
Kurzweil: This is a big leap, with no support to land on.
Tuomi: In reality, the belief in rapid development has often
paid off. Discontinuous innovations have created new uses and markets
for semiconductors and have produced an expanding market. Instead
of filling a market need, the semiconductor industry has actively
and aggressively created markets. At times the aggregate market
has grown at a speed that has appeared to be almost infinite in
relation to existing manufacturing capability.
Kurzweil: These references to "infinite" demand make no sense.
Nothing is infinite in today's world of technology.
Tuomi: The rapid growth of semiconductor industry, therefore,
has not been driven simply by technical advance in semiconductor
industry. Although the aggressive pricing policy has facilitated
the wide use of semiconductors, the high demand for semiconductor
technology has fundamentally reflected a continuous stream of innovations
that have occurred outside the semiconductor industry. In other
words, the apparent explosive big bang in semiconductor technology
is also an illusion.
Kurzweil: Tuomi's statement that "the apparent explosive big bang
in semiconductor technology is . . . an illusion" is another remarkable
conclusion.
Tuomi: . . . .many discussions on the future of Moore's Law
have focused on physical limits. In recent years economic considerations
have gained legitimacy also in this context, partly because Moore
himself has frequently predicted that the increases in chip complexity
will not be limited by physics but by the exponentially increasing
costs of manufacturing plants.
Kurzweil: Three-dimensional methodologies promise to reverse this
new approaches use self-organizing methods to allow many faulty
components in a system.
Tuomi: As computing technology becomes increasingly pervasive,
we eventually have to ask what benefits it actually brings. Fundamentally,
this question can only be answered in a theoretical framework that
is able to define development. In theory, there are many different
ways to approach this question, both old and new. It should, however,
be clear that development cannot be reduced to shrinking line-widths,
maximum number of components on a chip, or minimal manufacturing
costs.
Kurzweil: These remain, nonetheless, powerful driving factors,
although it is correct to say that there are other factors of innovation.
Moreover, exponential growth is not limited to memory or MIPS, but
includes essentially all information-based technologies. Other
examples include magnetic disk density (a completely independent
phenomenon), telecommunication speeds and price-performance, DNA
sequencing, brain reverse engineering, human knowledge, and many
others.
Responses to Ilkka Tuomi's "Kurzweil, Moore, and Accelerating
Change" 38
Tuomi: As Moore noted, on average integrated circuit component
counts grew rapidly during the 1960s, almost with a one-year doubling
time. During the first decade of microprocessors, the transistor
counts grew at about 22 months doubling time, when measured using
a least squares trend, which slowed to about 33 months during the
following decade. During the 1990s, transistor counts grew at varying
speeds. In the Intel's Pentium chips, the transistor counts grew
with around 54 month doubling time. After that the transistor counts
grew very rapidly, partly because large amounts of memory were added
onto microprocessor chips (Tuomi, 2002b).
Kurzweil: As noted earlier, Tuomi's 54 month doubling time is
not consistent with the historical data, as indicated in the graph
on transistors in Intel microprocessors provided earlier. There
are always less capable processors offered than the current standard,
so including these on the chart only serves to skew the results.
More importantly, measurements related to processors, whether transistor
counts, or MIPS ratings, are not the most meaningful items to measure.
We are more concerned with performance per unit cost. Also note
that MIPS measure does not take into consideration word size. Since
word sizes have increased over time, there has been even greater
progress than the MIPS ratings alone would suggest. See my graph
above on processor performance (MIPS).
Tuomi: Alternative growth rate estimates can be based simply
on transistor counts on representative microprocessors introduced
at two points of time. If we use the first microprocessor, Intel
4004, as a starting point, the exponential growth time for the 1971-82
period is 21 months, for the 1971-91 period 26 months, and for the
1971-98 period 27 months.This calculation indicates a slowing
down in the component growth rate. If we separately calculate the
growth rate for the 1982-91 period, it is about 35 months, and for
the 1991-98 period somewhat over 30 months. It therefore appears
that during the first decade of microprocessors component counts
increased much more rapidly than during the 80s. In the 1990s the
growth rate was faster, 30 months for both the first half and the
whole 1990-1998 period, but considerably slower than during the
first decade of the microprocessor history.
Kurzweil: These numbers are also dubious, but even less relevant
than MIPS ratings. There is an optimal number of transistors for
the functionality of a processor for a given word length and instruction
set, so measuring the number of transistors is not the most appropriate
measure of the exponential growth of price-performance. Nonetheless,
there has been exponential progress on this measure. See my graph
above on transistors in Intel processors.
Tuomi: If one studies the share of inputs that are used computer
manufacturing in the US, one can see that the biggest input cost
is associated with wholesale trade (about 14 percent of total output)
and semiconductor devices (also about 14 percent). This is followed
by payments for other electronic component manufacturing, software
publishers (about 9.5 percent), computer storage device
manufacturing, computer peripheral manufacturing, internal sales
in the computer industry, and management consulting services. A
more detailed study reveals that computer manufacturing requires
such inputs as air transportation, computer terminals, sheet metal
work, and food services and drinking places. The average price
changes in the 1990s are greatly influenced by the extremely rapid
drop of prices in the second half of the decade. For example, the
semiconductor input prices in the computer industry dropped over
40 percent annually during 1995-99. In the first half of the decade,
however, they declined only 11 percent annually.
Kurzweil: This is all irrelevant. We are concerned with what the
computer industry has been able to accomplish in terms of price-performance,
not in measuring what they pay for their "inputs," such as "food
services and drinking places." We see exponential improvement in
all facets of computer price-performance: MIPS per dollar, RAM capacity,
hard disk capacity, and other features.
Tuomi: A reasonable estimate for the average annual decline
in quality-adjusted computer prices is probably about 18-30 percent
during the last couple of decades, which corresponds to 2.6 to 4.2
year "doubling times."
Kurzweil: As I cited above, Tuomi makes this mistake repeatedly.
A 30 percent decline in price means a price of 70% (of the original
price) after one year, 49% after two years. Thus the price has
fallen to less than half in 2 years, so the doubling time is less
than 2 years, not 2.6 years. This consistent error is significant
since Tuomi is citing "high" doubling times as evidence that estimates
of 2 year doubling times are not accurate. Of course, the doubling
time depends entirely on what one is measuring.
Tuomi: Clouds are continuously changing their form. The ripples
on a stormy sea encode huge amounts of information. Any argument
about speed of change therefore has to neglect most sources of change.
The selection is obviously made by relevance. When we say that the
evolution is progressing at an accelerating pace, we have to abstract
away all change that doesn't matter. 20 Which sources of change
are left out of the equation depends on our present interests.
Kurzweil: Tuomi is missing the entire point of the law of accelerating
returns, which pertains to exponential growth of the capacity and
price-performance of information-based technologies. It is not
my position that all exponential trends go on indefinitely.
Indeed, exponential trends do hit a natural limit, but the key
point is that the known limits for computation and communication
are extremely high, vastly exceeding current technology. When I
refer to a paradigm shift (such as integrated circuits, or the Internet),
I am not referring to any type of change, such as "clouds . . .
. changing their form," but rather technological methods that provide
for the continuation of the exponential growth of the capacity and
price-performance of an information related technology.
Notes
1 Tuomi, Ilkka, "The Lives and Death of Moore's
Law." First Monday, volume 7, number 11 (November 2002).
http://firstmonday.org/issues/issue7_11/tuomi/index.html.
2 Ibid.
3 Ibid.
4 Ibid.
5Intel Corp. and
The International Technology Roadmap For Semiconductors: 2002
Update, International SEMATECH, 2002. http://public.itrs.net.
6 Microprocessor
Quick Reference Guide. Intel Research. http://www.intel.com/pressroom/kits/quickrefyr.htm.
Gregory Allen has also addressed similar issues in a mathematical
analysis of microprocessor performance growth ("The Bit Flip
Rate, Frequency and Transistor Density Equations," private
communication, 2003). He agrees that the "bit flip rate"
of microprocessors and transistor density are growing exponentially.
7 Data from Dataquest
and Intel reports.
8 Cullen, Steve.
"Semiconductor Industry Outlook." Instat/MDR. 2003.
9 Tuomi, Figure 4.
10 1976-1999: E.R. Berndt, E.R. Dulberger, and N.J.
Rappaport, 2000. "Price and quality of desktop and mobile personal
computers: a quarter century of history," 17 July 2000. http://www.nber.org/~confer/2000/si2000/berndt.pdf.
2001-2016: The International Technology Roadmap for Semiconductors:
2002 Update. On-Chip Local Clock: Table 4c Performance and Package
Chips: Frequency On-Chip Wiring Levels-Near-term Years (Update),
page 167
.
11 Average transistor price: Dataquest/Intel. Microprocessor
speeds: 1976-1999: E.R. Berndt, E.R. Dulberger, and N.J. Rappaport,
2000. "Price and quality of desktop and mobile personal computers:
a quarter century of history," 17 July 2000, http://www.nber.org/~confer/2000/si2000/berndt.pdf.
2001-2016: The International Technology Roadmap for Semiconductors:
2002 Update. On-Chip Local Clock: Table 4c Performance and Package
Chips: Frequency On-Chip Wiring Levels-Near-term Years (Update),
page 167.
12 http://www.ii.uni.wroc.pl/~jja/ASK/HISZCOMP.HTM,
http://www.siliconspirits.com/scomputer.html,
http://www.seagate.com/cda/products/discsales/index,
Byte magazine advertisements, 1977-1998, PC Computing
magazine advertisements, 3/1999, Understanding Computers:
Memory and Storage Time Life Editors. Time Life, 1990.
13 Internet Software Consortium, http://www.isc.org/ds/host-count-history.html
14 Trajtenberg, Manuel. Economic analysis of product
innovation: the case of CT scanners. Cambridge, MA : Harvard University
Press, 1990; Michael H. Friebe, Ph.D., President, CEO NEUROMED GmbH
(email)
15 "GenBank
Statistics," GenBank, National Library of Medicine, August
15 2003, http://www.ncbi.nlm.nih.gov/Genbank/genbankstats.html
16 See discussion in my essay "The
Law of Accelerating Returns"
17 Tuomi, Ilkka, "Kurzweil, Moore, and Accelerating
Change." Ilkka Tuomi
Curriculum Vitae. European Commission Joint Research Centre. http://www.jrc.es/~tuomiil/moreinfo.html.
18 Tuomi, Ilkka, "The Lives and Death of Moore's
Law." First Monday, volume 7, number 11 (November 2002).
http://firstmonday.org/issues/issue7_11/tuomi/index.html.
19 The International
Technology Roadmap For Semiconductors: 2002 Update, International
SEMATECH, 2002. http://public.itrs.net.
20 Fredkin, Edward, "A Physicist's Model of Computation,"
Proceedings of the 26th Recontre de Moriond, 1991.
http://www.digitalphilosophy.org/physicists_model.htm.
21 Tuomi, Ilkka, "The Lives and Death of Moore's
Law." First Monday, volume 7, number 11 (November 2002).
http://firstmonday.org/issues/issue7_11/tuomi/index.html.
22 Ibid.
23 Ibid.
24Intel Corp.
25 Tuomi, Ilkka, "The Lives and Death of Moore's
Law." First Monday, volume 7, number 11 (November 2002).
http://firstmonday.org/issues/issue7_11/tuomi/index.html.
26 Tuomi, Figure 1
27 The International
Technology Roadmap For Semiconductors: 2002 Update, International
SEMATECH, 2002. http://public.itrs.net.
28Tuomi, Ilkka, "The Lives and Death of Moore's
Law." First Monday, volume 7, number 11 (November 2002).
http://firstmonday.org/issues/issue7_11/tuomi/index.html.
29 Ibid.
30 Tuomi, Ilkka, "Kurzweil, Moore, and Accelerating
Change." Ilkka Tuomi
Curriculum Vitae. European Commission Joint Research Centre. http://www.jrc.es/~tuomiil/moreinfo.html.
31 Ibid.
32 Moravec, H., "When will computer hardware
match the human brain?" Journal of Transhumanism, Vol 1, (1998)
33 Tuomi, Ilkka, "The Lives and Death of Moore's
Law." First Monday, volume 7, number 11 (November 2002).
http://firstmonday.org/issues/issue7_11/tuomi/index.html.
34 U.S. Department of Commerce statistics, 1997-1998.
35 Tuomi, Ilkka, "Kurzweil, Moore, and Accelerating
Change." Ilkka Tuomi
Curriculum Vitae. European Commission Joint Research Centre. http://www.jrc.es/~tuomiil/moreinfo.html.
Figure 2.
36 Ibid.
37 All of Tuomi's statements in this section are
taken from his "The Lives and Death of Moore's Law." First
Monday, volume 7, number 11 (November 2002). http://firstmonday.org/issues/issue7_11/tuomi/index.html.
38 All of Tuomi's statements in this section are
taken from his "Kurzweil, Moore, and Accelerating Change." Ilkka
Tuomi Curriculum Vitae. European Commission Joint Research Centre.
http://www.jrc.es/~tuomiil/moreinfo.html.
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