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# Readers Respond to “Beyond the Limits of Science”

Letters to the editor from the September 2012 issue of Scientific American

September 2012 Image: Scientific American

QUESTION OF SCOPE

The title of the single-topic issue “Beyond the Limits of Science” left me scratching my head. To my eyes, the issue was packed with accounts of topics firmly within the limits of science. Science does have its limits, but I cannot understand why Scientific American would portray indisputably scientific endeavors as being beyond them.

Zachary Miller
Fleetwood, Pa.

SQUARE ROOT OF NOT

In “Beyond the Quantum Horizon,” David Deutsch and Artur Ekert describe how a π/2-pulse—a pulse of light with the same frequency but half the duration or amplitude of a π-pulse that would change the state of an atom's electron from 0 to 1, or vice versa—works in the computation for finding the square root of NOT (a logic gate in which inputting 0 or 1 results in the opposite figure). The authors state that if you “start with an electron in state 0, send in a π/2 pulse, then send a second π/2 pulse,” the electron will be in state 1. Yet how is this possible unless the superposition state retains a “memory” of where it came from? Wouldn't the second π/2 pulse have equal probability of bumping the superimposed state into either sharp state?

Robert Friefeld
Long Beach, Calif.

EKERT REPLIES: Two consecutive applications of the square root of NOT convert 0 to 1, or 1 to 0, but the intermediate superpositions of 0 and 1 are not the same in the two cases. Although both superpositions contain the same proportion of 0 and 1, they differ in the relative phase between the two. Thus, the superposition state indeed retains a “memory” of where it came from. The square root of NOT would be impossible if there were only one equally weighted superposition of the states representing 0 and 1.

MATH AND REALITY

“Machines of the Infinite,” by John Pavlus, states that the “universe itself is beholden to the computational limits imposed by P versus NP,” the question of whether tough problems whose solutions can be quickly verified can also be quickly solved.

This is a common misunderstanding. Nothing in the real world (whatever that is) is constrained in any way by our mathematics, physical laws or anything else we invented. Mathematics is merely a useful tool created to describe the universe. When we find something that we can't calculate or describe with our math, it may be that we've found a limit or constraint on the universe; it could also be that we've found a limit or constraint to our mathematics.

Ted Grinthal
Berkeley Heights, N.J.

ABSTRACT INTELLIGENCE

“Can We Keep Getting Smarter?” by Tim Folger, referred to researchers having attributed the Flynn effect, the fact that IQ scores have been steadily rising since the start of the 20th century, to the world perhaps becoming increasingly representational rather than actual. Yet that doesn't necessarily make us smarter. If an IQ test asked something like “How are fire and deer similar?” a modern person might answer that both words have four letters or one syllable. Most hunter-gatherers, however, would know about the concept of using fire to manage deer habitats. And even in the fairly recent past, people off the street knew how to make soap or to shoe a horse.

Because modern people interact with computers in a graphical user interface and have grown up playing video games, it is natural for us to quickly respond to simple geometric shapes. But a modern person in an unfamiliar environment can't respond to three-dimensional shapes in the same way.

“Smart” is a relative term. Our ancestors would marvel at how stupid we are that we can't even skin a rabbit or operate a printing press.

Tom Whitley
Seattle

I question using the abstract-reasoning sections of the Wechsler Intelligence Scale for Children (WISC) as proof of rising intelligence. Folger points out the paradox of these supposedly “culture-free components of intelligence” seeming to be altered by culture, but he doesn't mention that the tests themselves have altered the culture. After the tests were used, their concepts were everywhere, such as in books of puzzles and popular magazines. It is no wonder that each new class of children knew more correct answers.

Richard S. Blake
East Falmouth, Mass.

LIMITS OF LIFE SPAN

“How We All Will Live to Be 100,” by Katherine Harmon, reports on different strategies proposed to further increase human life span beyond what appears to be an approaching limit.

A 2005 paper by S. Jay Olshanksy and his colleagues in the New England Journal of Medicine has argued, however, that the U.S. might face a decline in life expectancy this century because of an increase in obesity, diabetes, hypertension and accompanying comorbidities. Considering such factors, a separation of wealthy and less privileged countries might represent more in-formative projections.

Harmon also writes that advances in sanitation might continue to extend our life expectancy. If the hygiene hypothesis is true, above a certain threshold, however, increased sanitation might have an opposite effect by increasing the rate of autoimmune diseases.

Thomas Boehm
Medical University of Vienna

BIGGER DISASTERS

“Questions for the Next Million Years,” by Davide Castelvecchi, explores environmental questions such as seismologist Thorne Lay's thoughts on the future commonness of large earthquakes, but several really big issues on the subject are overlooked. For instance, the biggest earthquake might topple every building in Los Angeles, but the atmospheric pollution generated by an eruption of the volcano in Yellowstone National Park would endanger everyone on the planet. How often do such supervolcano eruptions occur? The last was about 75,000 years ago, but Paleolithic scientists never published their observations.

Gerald Davidson
Red Lodge, Mont.

CLARIFICATION

“The Winters of Our Discontent,” by Charles H. Greene [December 2012], referred to the National Climatic Data Center forecasting a mild 2010–2011 winter for the eastern U.S.; that forecast originally came from the National Oceanic and Atmospheric Administration's Climate Prediction Center. The article also described La Niña as bringing warmer, mild winters and El Niño bringing colder, harsher ones; La Niña should have been described as bringing drier, mild winters and El Niño as bringing wetter ones.

Further, the article stated that by early March 2012, a strong and persistent atmospheric high-pressure system developed in the eastern Pacific; it should have said that the already existing high-pressure system in that region strengthened. The article also indicated that in certain circumstances El Niño and La Niña steer the trajectory of the jet stream; they do not steer it but are associated with climate conditions that can affect the jet stream's path.

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1. 1. tohlsson 04:19 PM 12/29/12

I read your special issue "Beyond the Limits of Science" with great interest. However, I stumbled over two inaccurate statements that appeared in two different articles, respectively. First, in "Are Nature's constants truely fixed?" by Gerald Gabrielse, which states that the "fundamental" constants in the laws of physics might be constants at least over 10,000 years. It might be true that one would not be able to observe any significant changes for some constants in such a time perspective, but generally all "fundamental" constants change (as all physical quantities do) with energy, or equivalently, evolve with time. In fact, taking the fine-structure constant as an example, it has been measured that it has the approximate value of 1/137 at zero energy, whereas it obtains the value of around 1/128 at an energy corresponding to the mass of the W boson. Thus, the value of the "fundamental" fine-structure constant is running with energy and the famous value of 1/137 is not particularly fundamental. Second, in "Beyond the Quantum Horizon" by David Deutsch and Artur Ekert, it was claimed that "People want to understand reality". Thus, it should be pointed out that physics is a descriptive natural science, which means that one can use it to model different phenomena in Nature in approximate ways, but we will never be able to "understand" how the phenomena work. If at all, such questions belong to other disciplines, and not to physics.

2. 2. And Then What? 08:33 PM 1/4/13

I find that I sometimes reflect on this notion we have of concepts of the Past, Present and Future.
The concept of Time and its apparent passage reminds me of the Real number Line used to visualize and define the Real Numbers and how the concept of what we define as Zero separates The Negative from the Positive.
If one were to visualize Zero, at the Quantum Level, we would probably find that it is, in point of fact undefined. So too maybe at the Quantum Level the Present is undefined. We perceive an event and say it happened "in the Present”, but at the quantum realm the Present is only a perceived point used by us to describe an event which in itself has no real Present in Reality.
If indeed Time itself is irrelevant to Existence in the world of Pure Energy and is only a perception manifest to us due to measurable effects upon Matter then what does this in fact says about Cosmic Reality beyond the scope of our understanding at the “Present” may be worth exploring if only to see what side roads it may lead us down and what hidden villages of knowledge may lay nestled along the way.
I suspect that what lies hidden from us because of our inability to reach out and Mentally manipulate, for want of a better term, Non Time-Dependent Events, such as our inability to quantify such events-packets free from the constraints imposed by the our concept of Time will someday provide for us a harvest of knowledge more vast than any we have so far reaped.
Take a simple for a simple example a single Energy Entity existing at a given point in Space and Time, for want of better description and visualize such an entity as suspended and frozen at the Quantum Level between its Past and Future and let us call such a point “The Quantum Present”. Now say for arguments sake that such an entity is “unrestrained” and hence would be free to choose from and infinite number of destinations in its journey from the Past to the Future. What could possibly influence it to move in any given direction over another and by doing so how would its movement influence its neighbor’s choices?

3. 3. vinodkumarsehgal 09:28 AM 1/5/13

"such as our inability to quantify such events-packets free from the constraints imposed by the our concept of Time will someday provide for us a harvest of knowledge more vast than any we have so far reaped."

But how it will happen? We were, are and shall continue to remain bound by our mental perceptional limitation.

4. 4. m 10:15 AM 1/5/13

I was commenting to myself the other day, that i should research how soap is made. Even though I knew its probably vegetable oil with all the impurities boiled out of it, cooled, put into bars with some gelling agent, natural colouring agent and perfume.

Still im sure theres something I dont know about soap making with my iq.

5. 5. m 10:22 AM 1/5/13

Ah before i forget, i invented a new quotient for iq the other day, the feedforward mechanism (connectivity number) times the feed back capability. Yeah impossible to find out and know today, but one day we could scan our brains and be able to download that print into a machine. At that point we could also resolve the actual iq of a person with my quotient.

I completely agree, once a person has seen the questions before their "iq" increases. Though tbh i was confused by some iq questions (when i was a young boy) clearly having multiple answers and always gave the least likely but correct one it was. I probably always scored low marks even though I knew what they were doing, lol.

Now most tests show me as gifted, but honestly i think im as stupid as a horse sometimes.

6. 6. vrpelican 06:02 PM 1/23/13

New subscriber 2012
Comment on Starship Humanity
Interesting article, but still thinking inside the box.
Before man ventures out on the ark he will have likely
evolved beyond the need to continue the practice of animal husbandry. No need for all those animals and
on-board farms.
I also anticipate that human bio-engineering will have addressed many of the anticipated problems long before
there is a Bon Voyage party. And there may be many discoveries and innovations between now and then, surprises and epiphanies also written in the stars.

Comments from a person who is not a scientist but who was impressed at an early age by Socrates, "an unexamined life is not worth living".

Victor Romulus

7. 7. vrpelican 06:20 PM 1/23/13

BTW
Picked up SA What Makes us Human today. I have often thought about the evolution of not the human body and mind, but rather the beginning of humanity itself. Just how far back can we ask the question, "are they human?" and the thought that a certain lineage may have become extinct, an heredity of the most human-to-date of all, lost forever.

Victor Romulus

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