Nature's Impossiblities.

by Donald E. Simanek

The difficult we do right away. The impossible takes a little longer. —Engineer's joke.

Judging from my email and occasional eavesdropping on web forums, I conclude that there are many people in this technological world who sincerely believe that "anything is possible" in science and engineering. They have seen science produce wonders previously thought impossible, and are confident that, given enough time, science will conquer all of the challenges we now find unimaginable. They love to quote the line "They laughed at Galileo, didn't they?" (Or, substitute the name of any renowned scientist or inventor.)

In particular, they dislike any suggestion that particular things might be impossible, especially particular things they desire very strongly, such as perpetual motion machines and over-unity machines. Sometimes this is expressed as an almost religious conviction that if mankind needs something very badly, then somehow, someday, some clever person will find a way to accomplish it. It is a "faith in the possibility of unlimited progress". So, we are running out of fossil fuels? Not to worry, someone will find a substitute fuel in great abundance. Is our population growth threatening to exceed the resources of earth? No problem. By the time that gets dicey, we will be colonizing the planets, and eating delicious synthetic food made from industrial waste. This sort of thinking has (apprently) always worked for us in the past, so surely, some think, such progress will continue forever.

I submit that this excessive faith in science stems from a profound misunderstanding of science. It is a selective reading of history, concentrating on past instances of success, without examining why those successes were possible. Also, people love stories (often only partly true) of cases where pessimistic predictions were found to be wrong. Very often these pessimistic predictions were casual hunches and not carefully thought out analyses, and some of these stories are simply urban legends. The "bumblebees cannot fly" legend is one such case.[1] Such negative predictions, especially when made by prominent persons of history, make entertaining reading, and I have a collection of them on my website, titled It'll Never Work. Equally entertaining are past optimistic and fantastic predictions of future developments that haven't come about, and never will. Several published books have mined those as cautionary examples of the dangers of overconfidence in science and technology. [2]

Throughout the history of technology, people have been fascinated with the possibility of a machine that would do useful work while requiring no energy input, or at least much less energy than conventional machines that burn fossil fuels, or use "natural" sources such as wind and water. Their goal is a machine that puts out more energy in the form of useful work than it takes in, a hypothetical device that they call an "over-unity" machine, because its energy efficiency would be greater than one. Sometimes this is loosely called a "perpetual motion machine" because if some of its output energy were used to provide the input energy, it could run forever and still put out some useful work. Needless to say, no one has achieved this goal.

One might have thought people would give up this effort once scientists formulated and then understood the laws of thermodynamics, which tell us that energy is strictly conserved in any mechanical device, whatever its detailed construction, whether it be strictly mechanical, or electrical or magnetic, or whatever else you might conceive.

But ever-optimistic inventors saw these laws as a challenge. Surely the laws must be wrong. How can scientists be so arrogant as to declare anything to be impossible? We haven't tried everything yet. How can you know that some future clever invention couldn't exploit a loophole in known science? Science has been wrong in the past, maybe the thermodynamics laws are incorrect, at least in some as-yet-unobserved case. In particular, they could be wrong in the case I want to be true, say the perpetual motion believers.

So, the perpetual motionists forge on, tinkering and fiddling with wheels, gears, magnets and fluids, each hoping to be the one to stumble on the secret of unlimited energy. It must be possible, they say, because mankind desperately needs it. Each year patents are issued for devices that any competent physicist would find laughable. The internet has many websites and forums publicizing incredible devices along with claims of the potential of achieving incredible results—with a little more refinement and tinkering. These accounts are frustratingly short of details of experimental results. Indeed, they sometimes describe a machine as "working" that hasn't yet been built, even in prototype.

Devices using magnets are particularly popular these days. These folks are having fun tinkering with magnets, but haven't produced any results that confirm their hope (conviction) that such devices are capable of producing more energy output than input.

Some of the perpetual motionists reject the notion that they are trying to defy the laws of thermodynamics, or any other laws of physics. They are hoping to make a machine that will somehow tap a "natural" source of energy (free energy) in the universe that we haven't discovered yet. A successful over-unity machine would in fact constitute the discovery of that energy. The machine itself would be a "detector of invisible free energy".

Others pin their hopes on certain notions currently popular in speculative theoretical physics, such as "dark energy", "dark matter", and "zero point energy". After all, these are "energy" and even matter can be converted to energy, so it must be out there, free for the taking. These folks propose, and some even build, machines that are superficially indistinguishable from previous attempts to get energy from nothing, only these folks claim that the energy will not be "from nothing" but from energy that's invisible and all around us.

Personally, I think those who seek to make such "free energy" machines are destined to fail. But my reasons aren't easy to explain. Since I have been a physicist my entire career, I have a different perspective on these questions than non-physicists do. I am also well aware that science is not yet complete, and that present-day scientific laws and theories will surely be modified and improved in the future. We don't know everything yet, and probably never will. Perpetual motion believers hope that there's a flaw or loophole in our understanding just so that it will allow clever inventors to exploit a "sea of energy" that pervades the entire universe. The catch is that (1) that "sea" of zero point energy is locally very dilute, and only tiny amounts of energy would be within the "grasp" of such a machine, (2) Nature has certain "gotchas" in its laws that provide no way to extract even that energy to produce useful work. In fact, the laws specifically prevent this. Finally, even if we are wrong about those "gotchas", present science gives us no clues as to how to get around them, so inventors are like blind men fumbling around in the dark, hoping that something might magically work if they tinker with it long enough. Along the way they are encouraged when they see some result that was unexpected (to them), and seemingly not in accordance with their (limited) knowledge of physics. They proclaim such observations as "breakthroughs".

In their enthusiam, the inventors seem to think that "environmental" energy comes completely free. Every such source we know of requires some energy to extract from nature. Extraction machines aren't perfectly efficient, and no one knows how to make a perfectly efficient mechanism. If they did, that itself would be a perpetual motion machine, even if it didn't have over-unity performance.

Another thing they overlook is that the physicists' "zero point energy" is a "phantom" energy, a mathematical fiction that is part of the mathematical theory of quantum mechanics, and is not necessarily equivalent or convertible to what we think of as "real" energy (of a kind that can be converted to useful work). These "energies" are something of the character of the concept of the "electric field lines" that are shown in pictures depicting how charges act upon other charges, or the "gravitational field lines" from masses. Physicists know that these are not "real" entities in space, but only a convenient mathematical concept to help us visualize what's going on and what would happen if a charge were placed at a certain place. No one would think that we could reach into space and grab a handful of field lines and put them in a bottle.

Even people who do not for a moment accept the possibility of perpetual motion sometimes fall into this philosophical trap. They say, "Perpetual motion can't work because you can't create energy from nothing." This is a weak argument. They are thinking of energy as a "stuff" or a "substance", and implicitly assuming that stuff is indestructible and cannot be manufactured from something else." But energy isn't material stuff. Energy is a convenient mathematical concept for doing the "bookkeeping" as we observe how things interact and influence each other. Energy is an "accounting" scheme for describing the behavior of physical things.

Why are so many people fascinated by magnets? Probably because magnets are not part of our daily experience, and in certain situations behave in ways that are surprising (and seem "magical") when first observed. Those who do laboratory physics and electrical engineering have become familiar with the behavior of magnets, and know the laws of their behavior. The laws are mathematically complex, or rather, making predictions with those laws can be complex, because when magnets interact the shape of the magnetic field around each one changes. Still, the bottom line is this: we know the laws they obey and nothing we've ever done with magnets has shown the laws to be violated. Furthermore, the laws can be shown, mathematically, to be fully consistent with strict conservation of energy and momentum—with no exceptions. A vast amount of experimental evidence confirms that. If there were flaws in these laws, that fact would surely have shown up in the operations of one or more of the electromagnetic machines (motors, generators, etc.) that keep our industrial technology humming along. So the bottom line is that those who hope for a magnetic perpetual motion machine are doing so because they do not yet understand the physics and applications of magnets.

The trouble with miracles is that they are not reliably repeatable on demand.

But there are philosophical considerations also. These have to do with the concept of nature's lawfulness. Does nature operate according to strict and regular laws (even if we do not yet know all of those laws)? If nature is perfectly lawful, we can predict its behavior in particular situations, although not perfectly (since our measurements are never perfect). Or does nature sometimes do something "capricious" and unpredictable? In that case, our predictions might be far off the mark in that case, and the event would qualify in some people's minds as a "miracle".

In physics, when something like an unexpected scientific observation turns up, more careful examination usually shows that our predictions were mistaken (we blundered in the calculation), or we overlooked a subtle condition or variable. But in a few much-publicized cases, some previously accepted law was at fault, and the observation tells us something new that may lead to refinement of a that law. Then we realize that nature was behaving lawfully after all, we just hadn't gotten the law completely right. No such case, in the whole history of science, has convinced us that nature has ever, not even once, behaved in a capricious manner. So we conclude that "nature is strictly lawful" and it is our job to keep trying to express those laws better and better. Actually we are trying to construct mathematical laws that fully describe nature in all cases. But we aren't so arrogant as to assume that these laws we invent are "nature's laws". We know, from past examples, that two different sets of laws may describe nature equally well, and to say that one set is "better" or "truer" than the other is saying too much.

Lest my meaning be misinterpreted, I am talking about basic laws here: laws like Newton's laws of mechanics, Maxwell's laws of electrodynamics, the laws of thermodynamics, etc. Sometimes, things unexpected to us occur in complex situations, without violating any basic laws. It may rain when no rain was predicted. These are situations where outcomes depend on the interaction of so many basic laws of nature in combination that we can't possibly know the relevant variables well enough to make precise and fully reliable predictions, or we don't have the computing power to process the data.

But even in complex situations as this, there are some physics laws that can be tested, after the fact, and shown to have been fully obeyed. No matter what the weather does tomorrow or next week or next year, it will never violate the laws of thermodynamics, the conservation of energy, the conservation of momentum, the conservation of angular momentum, etc. There is a class of physical laws, called "conservation laws" that allow us to make definite, measurable predictions about entire complex systems without knowing everything that's going on in the system. Physicists love such laws, because of their robust character. They allow us to make correct predictions even though we have some ignorance of the system. And, so far, nature has not let us down.

Now these conservation laws are not laid down by scientists as dogma by fiat. Nature has imposed them upon us, and we express them in words and mathematics because they are so useful. Such laws are inferred (generalized) from the whole history of observation of what nature does, and from experiments done in laboratories around the world (and by observations by astronomers in the larger laboratory of the universe). They have been tested not only experimentally, but also by forging the mathematical links between them and the other fundamental and well tested laws in all fields of science to convince ourselves that they constitute a logically consistent and comprehensive framework for describing nature.

That's why we confidently say, "No one will ever make a machine that outputs more useful work than the amount of energy input to it." Such a machine would violate conservation of energy, and we can show mathematically that it would also seriously violate Newton's law F = ma, Newton's third law, and even conservation of momentum. These violations would not be small and easily overlooked. They would be large and serious violations, easily observed. Yet no such violations of these laws have ever been observed in the history of science.

To return to the perpetual motion enthusiasts... Even though they don't articulate them, they have some philosophical preconceptions in common. While they recognize that nature behaves predictably and lawfully, they hope that there's some deficiency in our understanding of these laws that would allow for unlimited production of useful work greater than the energy used. They fail to appreciate the implications of this, if it were so. They think that it could be done without modifying other known and reliable laws of physics, such as Newton's laws. They do not appreciate the mathematical/logical interdependence of all of these laws. They treat each law of physics as an independent and separate entity. If there were a machine that, say, put out 10% more useful work than its energy input, that could only be so if all of the fundamental laws of textbook physics were seriously wrong. Do they really think that is so? No, they still think all the laws are independent of each other.

Some also have the mindset that "Anything is possible if you are clever enough and tinker with it long enough". If we took that idea seriously, we'd have to conclude that any law of nature could be broken or circumvented. Some go farther, and, with religious conviction, say, "If you believe in something, you can make it happen". This is "magical" thinking of the sort held by the ancient alchemists. Do these people really suppose that future technology will allow someone to jump over the moon with an unpowered pogo stick? Or that medical science might produce a human who could run a one-minute mile? Or perhaps allow someone to walk through a brick wall without injury to himself or the wall? Perhaps they also believe it will someday be possible to teleport a human being anywhere in the universe, or jump backward in time. Well, maybe perpetual motion machines would power these innovations.

Seriously, we must admit that some things are clearly impossible in nature, though we don't always know which ones they are. Some are impossible logically, and are of little interest as scientific examples: It's impossible to make a four-sided triangle. It's impossible to make a triangle in a plane with equal sides and unequal angles. You can't make a perfect circle in a plane with a circumference equal to 8 times its radius. Are these physical impossibilities, or are they logical impossibilities? Logical, certainly. But if our universe is structured on Euclidean geometry, they become physical impossibilities. And from what we have learned, the universe is, very nearly, Euclidean, and certainly is in our local region of it. [3]

In a wider sense, all of physics is fundamentally geometric in nature, when you consider time to be part of that geometry. All the perpetual motion proposals I have seen, when examined, are seen to be flawed geometrically. Geometry is what limits what can happen in the universe and what cannot. But then, geometry can be considered our modeling framework for physics, and who is to say that geometry has any "existence" without reference to the universe? There are those who say, "the only reality is mathematics." That is a philosophical proposition, not a scientific one. The whole question of "reality" is a philosophical concern, and physicists need not fuss about it in their everyday work. They can do physics quite well, whether anything is "real" or not, so long as observations indicate that what we observe has reliable and lawful behavior.

Endnotes.

[1] The story goes that a famous aerodynamicist was asked how bumblebees can fly with such small wings relative to their body weight. He did some back-of-the-envelope calculations, and concluded that their wings were too small, and, aerodynamically, they shouldn't be able to fly. This story is much quoted in various forms, with different details, but without any documentation of who made the calculation, and when. So one suspects it is an "urban legend".

This popped up on an internet discussion group back in 1999, with this interesting response.

Subject: FW: Bumblebee Flight
Date: Wed, 13 Oct 1999 12:47:46 -0700

A long time ago [1989] I wrote an article for the journal American
Scientist entitled: "The Flight of the Bumblebee and Related Myths of
Entomological Engineering" (Am. Sci., Vol. 77, pp. 164-8).  In this I
gave what still appears to be a correct account of the "Didn't the
aerodynamicist prove that the bumblebee can't fly ? [sarcastic ha ha]"
story.  I too had tried to find the name of "The aerodynamicist" who
did this to us.  After a long search I was told by a very reputable
source that he thought that individual (who was badly misrepresented
subsequently by the "press") was the Swiss gas dynamicist Jacob
Ackeret - a famous name in supersonic aerodynamics.  It was about the
right vintage, so I wrote that in my article without naming Ackeret
explicitly.  Follwoing publication, however, I got mail.  Boy did I
get mail - including half a dozen Xerox copies of portions of the text
of the book Le Vol Des Insects (Hermann and Cle, Paris, 1934) by the
famous entomologist August Magnan.  On page 8 of the introduction, one
finds:

    "Tout d'abord pouss'e par ce qui fait en aviation, j'ai applique' aux
    insectes les lois de la resistance del'air, et je suis arrive' avec
    M. SAINTE-LAGUE a cette conclusion que leur vol es impossible."

Thus the culprit is finally named: Sainte-Lague, Magnan's lab
assistant who was apparently some sort of engineer. 

Share and enjoy.

John McMasters
Technical fellow
The Boeing company
Seattle, Washington

Rough translation of the quote from Magnan: "In the beginning, being encouraged by one who is into aviation, I have applied to the insects the laws of resistance for air, and I reached, with Mr. Sainte-Lague, the conclusion that their flight is impossible." If any reader can supply a more accurate translation, please let me know.

[2] Books that treat the theme of over-optimism about science and technology include: "Wasn't the Future Wonderful?" by Tim Onosko (1979), "Out of Time" (2000) by N. Brosterman, "Where's My Space Age? The Rise and Fall of Futuristic Design" (2003) by Sean Topham and "Follies of Science. 20th Century visions of Our Fantastic Future", by Eric Dregni and Jonathan Dregni (Speckpres, 2006). The last of these is nicely illustrated, but has superficial text and too many errors to suit me.

[3] The importance of geometry in physics could justify a separate essay. The conservation laws of energy, momentum and angular momentum are perhaps the most fundamental physics laws we have. And where do they arise? From the underlying geometry of the universe. This was shown by mathematician Emmy Noether in 1915 and published in 1918 and Noether's theorem is recognized as the foundation of the conservation laws of physics. While the various versions of this theorem are highly mathematical, the essence of them is this: If a physical process obeys laws that are invariant (constant) over time, then the energy of this process is conserved. If a process obeys laws that are invariant under spatial transformation, then its momentum is conserved. If a process obeys laws that are invariant under rotation, then its angular momentum is conserved. This is seldom mentioned in popular treatments of perpetual motion. Once its significance is appreciated, it makes the efforts of perpetual motionists seem pathetically misguided. They are playing around with wheels, gears, pulleys, magnets and electrical devices, all of which operate within the strict laws of physics imposed by geometry, and therefore cannot achieve what the inventors hope for. Now if these folks could figure a way to make something move continually around a closed path downhill all the way, they might be onto something. They would have modified the geometry of space, which would open up wonderful possibilities for new physics. But no one has a clue how to do that, and no hint that it's even possible.

This document is evolving. Suggestions are welcome for other points I ought to discuss. Contact me at the email address to the right. This revision: May 2008.

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