[museum1.jpg]

        Redrawn and colored version of M. C. Esher's lithograph WATERFALL

  This museum is a celebration of fascinating devices that don't work. It
  houses diverse examples of the perverse genius of inventors who refused
  to let their thinking be intimidated by the laws of nature, remaining
  optimistic in the face of repeated failures. Watch and be amazed as we
  bring to life eccentric and even intricate perpetual motion machines
  that have remained steadfastly unmoving since their inception. Marvel
  at the ingenuity of the human mind, as it reinvents the square wheel in
  all of its possible variations. Exercise your mind to puzzle out
  exactly why they don't work as the inventors intended.

  This, like many pages at this site, is a work in progress. Expect
  revisions and addition of new material. Since these pages are written
  in bits and pieces over a long period of time, there's bound to be some
  repetition of ideas. This may be annoying to those who read from
  beginning to end, and may be just fine for those who read these pages
  in bits and pieces.

Galleries

    * [1]The Physics Gallery, an educational tour. The physics of
      unworkable devices and the physics of the real world.
    * [2]The Annex for even more incredible and unworkable machines.
    * [3]Advanced Concepts Gallery where clever inventors go beyond the
      classical overbalanced wheels.
    * [4]New Acquisitions. We're not sure where to put these.
    * [5]Will They Work? These ideas don't claim perpetual motion or
      over-unity performance, nor do they claim to violate physics. But
      will they work?
    * [6]Whatever Were They Thinking? The rationale behind standard types
      of perpetual motion devices.
    * [7]The Gallery of Ingenious, but Impractical Devices. Not perpetual
      motion but certainly ill conceived.
    * [8]The Basement Mechanic's Guide to Building Perpetual Motion
      Machines.
    * [9]The Basement Mechanic's Guide to Testing Perpetual Motion
      Machines.
    * [10]Thoughts on testing self-motive wheels.
    * [NEW] [11]Fake Perpetual Motion Machines You Can Build.
    * [12]Perpetual Futility, A short history of the search for perpetual
      motion.
    * [13]The John Worrell Keely Memorial Gallery.
    * [14]Hall of Machinery. Watch these machines turn forever.
    * [15]Unworkable Devices as Fine Art. Special exhibit now open.

    Themed Galleries: The evolution and persistence of unworkable
  concepts.
    * [16]Center of gravity analysis of machines.
    * [17]The shifting-mass overbalanced wheel.
    * [18]Self-acting pumps.
    * [NEW] [19]Constrained overbalance. The overbalanced cross.

  Insanity: doing the same thing over and over again and expecting
  different results.

       —Anon.

    * [20]Belt and pulley Devices.
    * [21]The Roberval balance.
    * [22]Back to Basics. Simpler isn't always better.
    * [23]The bucket-brigade wheel.
    * [24]Buoyancy misconceptions.
    * [NEW] [25]Siphon misconceptions.
    * [26]Surely they can't be serious?
    * [NEW] [27]Theory of perpetual motion machines.

    Perpetual motion puzzles. [NEW]
    * [28]Buoyant Optimism. Power from buoyancy.
    * [29]Leonardo wheel puzzle. A perpetual motion wheel from Leonardo's
      notebooks.
    * [30]Bessler's belt puzzle. An overbalanced belt device from
      Bessler's collection.
    * [31]The eccentric wheel puzzle. Unbalanced but unmoving.
    * [32]The overbalanced cross. A curved ramp forces rods to perpetual
      overbalance.

    The Reading Room.
    * [33]Nature's impossibilities.
    * [34]Why won't my perpetual motion machine work? For those who want
      quick answers.
    * [35]Perpetual misconceptions.. Basic physics perpetual motion
      inventors miss.
    * [36]Things to consider before you rewrite classical physics.
    * [37]Basic concepts of classical physics.
    * [NEW] [38]Are physics laws universal?
    * [39]Violating Newton's Laws.
    * [40]On a frictionless level plane, will a cylinder roll forever?
      No, but the reasons are interesting.
    * [41]A defense of the quest for perpetual motion. by Ken Amis.
    * [42]Letters to Ken Amis.
    * [43]Patents for unworkable devices.
    * [44]Physics 101 for perpetual motion machine inventors.
    * [45]What is Energy?
    * [46]A long history of failure. Villard's wheel.
    * [47]The psychology of perpetual motion machine inventors.

                            Related Galleries.

    * [48]Gallery of artistic impossibilities.
    * [49]Gallery of 3d stereo artistic impossibilities.
    * [50]Dead downwind faster than the wind. Can an unpowered vehicle
      move directly downwind faster than the wind?
    * [51]Donald Simanek's Front Page.

                              Web resources.

    * [52]Deceptions by Peter Parsons. We don't talk much about
      deliberate contemporary scams and deceptions on these pages. We
      don't have to, for this excellent site debunks them thoroughly.
      Click on the "scams" tab for more. The site also has information on
      both genuine and bogus energy saving strategies.

  The seekers after perpetual motion are trying to get something from
  nothing.
  —Sir Isaac Newton

                             The Main Gallery

    * [53]It'll never work!
    * [54]Overbalanced wheels.
    * [55]Stevin's problem.
    * [56]More on Stevin's Principle.
    * [57]Friction and idealizations.
    * [58]Tapping quantum weirdness. NEW!
    * [59]What about free energy?
    * [60]Buoyancy motor 1.

  If at first you don't succeed...

  Somebody said it couldn't be done
  But he, with a grin, replied
  "You shouldn't say it can't be done
  At least until you've tried."
  So he set to work; armed with a ton
  Of zeal he got right to it.
  He tackled that thing that couldn't be done;
  But he couldn't do it.
       —Anon (Parody of Edgar Guest.)

    * [61]Buoyancy motor 2.
    * [62]Buoyancy motor 3.
    * [63]Buoyancy motor 4.
    * [64]Capillary motor.
    * [65]Capillary wheels.
    * [66]George Sinclair's siphon.
    * [67]The Schadewald gravity engine.
    * [68]Simanek's bouncing ball engine.
    * [69]Gravity shield engine.
    * [70]The Classic magnetic shield engine.
    * [71]Links to other sites.
    * [72]Bibliography.

                             It'll never work!

                               [fludd.gif]
                     Closed-cycle mill, 17th century.

      [perpmach.gif] The term "perpetual motion machine" has several
                               definitions.
   1. Any device that continues its motion forever, without any speed
      reduction. This is a literal interpretation of the words.
   2. Any device whose operation would violate established laws of
      physics, or would depend upon purely speculative laws unknown to
      physics. This is the colloquial usage.
   3. A machine that perpetually puts out more energy than it takes in.
      Nowadays this is called an "over-unity machine" since its power
      efficiency would be greater than one.

      I will include the last two of these under the term "unworkable
   devices". The first one does not violate any fundamental physics, but
   it does not happen in large-scale structures because of two facts of
   nature: (1) no materials are perfectly rigid bodies and (2) friction
    and other energy-dissipative processes are always present. The only
  systems we know of, such as atoms, that seem to exhibit constant energy
  and momentum forever (if undisturbed) are such a nature that we cannot
  directly verify whether there's really any motion going on within them.
   Our concern is not with these, but with systems that would appear to
  violate physics laws on the macroscopic scale—machines that have cyclic
    operation and could be made to produce useful work forever, without
                               energy input.

  The Perpetual Quest

  Seekers of Perpetual Motion,
  Have fervent faith and saint's devotion.
  The Gods of Physics duly smite them
  To be reborn ad infinitum.

  —Jonathan Harris

  Perpetual motion machine proposals are often dismissed by scientists in
      a manner that appears to the layperson as hasty rejection using
   dogmatic assertions that such machines are prohibited from working by
    the "laws of thermodynamics". This does not satisfy the person who
   "knows" a little physics, but considers the laws of thermodynamics a
   bit mysterious. The very character of such laws is off-putting to the
   average person, because they have an air of finality and negativity.

  Thermodynamics laws and conservation laws have great power because they
  allow us to predict certain things about a system without analyzing all
    aspects of the mechanism. They even allow confident predictions in
  spite of our ignorance of some details or experimental difficulties in
  examining them. The experienced scientist will use these to evaluate a
   proposed device, which seems to the non-scientist to be a failure to
                         consider all the details.

  Of course physicists don't claim that any physics laws represent final
     and unalterable truth. The perpetual motion (PM) machine inventor
    pounces on this and says "Such laws would have us give up trying to
  discover anything new! What if there were a flaw in these laws, a flaw
                   that we could discover and exploit?"

  The only way of discovering the limits of the possible is to venture a
  little way past them into the impossible.

  — Arthur C. Clarke (Clarke's second law)

   It's a historical fact that the laws of thermodynamics were initially
    proposed to describe the fact that all previous attempts to achieve
  perpetual motion had failed. We've learned more about these laws since
  then, and have a much better understanding of them and why they are so
        powerful in describing what can and can't happen in nature.

     Any particular classical mechanical PM machine can be shown to be
  faulty in concept or execution by far simpler and conclusive means. The
  obvious way is to simply test the machine to see if it lives up to the
  inventor's claims. Fraudulent claims may sometimes be exposed this way.
   But the inventor's usual reaction to the failure of his device is to
  say, "It just needs a bit more work to refine and improve the design or
                           reduce the friction."

     On another level are proposals that haven't yet been built. Such
   proposals may come from honest (though perhaps misguided) people who
  know some physics or engineering (but not enough). How can we determine
    whether these are worth the time and trouble to develop? We may not
     have to go to the trouble and expense of building them. Perpetual
   motion proposals can be shown to be based on faulty reasoning, or on
  misunderstanding or misapplication of well-known and well-tested basic
                      laws and principles of physics.

   This can be a useful exercise for interested laypersons, and for high
   school and freshman college students taking physics, even before they
   have been exposed to the laws of thermodynamics. My purpose, in this
   document, is to subject some of the classic perpetual motion machine
     proposals to such analysis. In the process we will come to better
     understand the basic physics laws, and understand how they can be
      misunderstood, misinterpreted and misapplied. This exercise can
                strengthen one's understanding of physics.

  He is wise who gains wisdom from another's mishaps.
  —Plutius Syrus

      I will be interested in examining examples of these classes of
                           proposals and claims:

    (1) Devices that are claimed to remain in continual motion without
     input of energy and without producing output work. Obviously such
   devices would require energy to get them moving, but none thereafter.
    This description is nothing more than a statement of what perpetual
    motion means. These devices (if they actually worked) would have no
      purpose other than to amaze onlookers and annoy physicists and
   engineers. Such devices would not necessarily violate any fundamental
    physics laws or principles. Stable atoms are physical objects whose
  internal processes continue forever without loss of energy, if the atom
   is not disturbed. So they are examples of "perpetual motion" (moving
  forever), but in the physics literature these aren't called "perpetual
  motion machines". That term is reserved for a device that would violate
    one or more of the laws of thermodynamics. This is because the word
    "machine" is reserved for devices that produce an output of useful
  work, while these continually turning systems don't output any work and
                        therefore aren't machines.

   Some folks cite the motion of planets around the sun as an example of
   perpetual motion. On the macroscopic scale we can show that perpetual
  motion isn't happening, even without waiting around for an eternity. If
   the motion of a system is observed for a finite time and found to be
  decreasing in speed, then clearly it is losing energy continually, and
  can't move perpetually. This is the case even for the solar system, as
   mechanical energy and tidal deformations dissipate mechanical energy
  into thermal energy. There are no macroscopic (large scale) mechanisms
   known that move without slowing down, and it is usually due to those
   ever-present energy dissipative processes such as friction. The fact
     that these dissipative processes are always present is a fact of
   nature, though we don't usually elevate that fact to the status of a
   "law of nature". This fact, however, is not the sole cause of failure
        of all perpetual motion machine proposals, as we will see.

   (2) Devices that are claimed to remain in motion without energy input
  while still producing output energy. Such proposed devices may require
  a push to get them started, but no input energy thereafter. This is the
     kind of machine inventors seek. Sometimes the inventor refuses to
    disconnect the starter battery after the machine is moving. This is
                                suspicious.

  Human opinion is scarcely anything more than the history of human
  errors.
  —Voltaire

    (3) Devices that require energy input to remain in motion, but are
   claimed to produce output energy greater than the input energy. These
      days some folks call these "over-unity" machines, because their
  inventors claim they have energy efficiencies greater than one. Clearly
   such a machine (if it existed) could be engineered to be a class (2)
   machine by simply diverting part of the output energy and feeding it
  back to the input to drive the machine. Curiously, inventors who claim
  to have made an over-unity machine resist any suggestions that they do
  this in order to conclusively prove their claims for the machine. This
                            is also suspicious.

   (4) Devices that tap some hypothetical universal all-pervasive "free
  energy" that the inventors imagine fills all of space. Back in the 19th
    century it used to be the energy of the luminiferous ether that was
   supposedly being tapped. Now that we no longer take the existence of
     the ether seriously these folks claim to be tapping some sort of
   "energy of the vacuum." Anyway, they claim, it's "out there" and free
     for the taking. If there really were such an energy source, these
    machines wouldn't be violating any physical laws. Unfortunately the
      postulated source of energy is often concocted just to suit the
   purposes of the inventor, and is entirely a product of the inventor's
  imagination, unsupported by any other independent evidence. So, to the
  objective observer, these machines are experimentally and theoretically
                     indistinguishable from type (3).

    Since inventors (seekers) of free energy devices claim that such
    machines do have energy input, they reject the label of
    "perpetual-motion machines". They also reject any suggestion that
    they could divert some output energy to the provide the necessary
    input, on the excuse that the machines are only capable of taking in
    energy from a "free energy" source, or that the "free energy" is of
    a subtly different character from ordinary energy.

  Scientists classify PM machines by reference to the thermodynamics laws
                            they would violate.
    * Perpetual motion machines of the first kind violate the first law
      of thermodynamics. They produce more energy output than input, that
      is, they have an efficiency greater than one.
    * Perpetual motion machines of the second kind violate the second law
      of thermodynamics. They would involve zero or negative changes of
      entropy.

  I won't use this classification much, for I want to avoid any appeal to
  the laws of thermodynamics in this document. My intent is to show that
   all unworkable devices violate more fundamental laws, laws that have
   been well-tested, well-established, and well-integrated into physical
     theory. Usually these are laws presented in undergraduate physics
    textbooks. But the examples I intend to analyze are those that are
    given inadequate analysis in standard books and articles. Many were
   originally proposed not as workable machines, but as clever challenge
    puzzles and paradoxes to test understanding of physical principles.

                                  [73]Top
    __________________________________________________________________

                           Overbalanced wheels.

  [baskara1.gif] The overbalanced wheel perpetual motion idea apparently
    originated in India, in the 8th century CE. In his Sysyadhivrddhida
   Tantra (748 CE) the Indian astronomer Lalla described a self-rotating
          wheel driven by mercury moving along its curved spokes.

   A variation of this idea was described by the Indian author Bhaskara
  (c. 1159). It was a wheel with containers of mercury around its rim. As
       the wheel turned, the mercury was supposed to move within the
  containers in such a way that the wheel would always be heavier on one
   side of the axle. [GIF by Hans-Peter Gramatke, used with permission.]

  Various spellings are seen: "Honecort" and "Honnecort". "Villard" is
  sometimes seen as "Vilars", "Wilars" or "Willars".

  This idea appears again in Europe in the year 1235 when the French
  architect Villard de Honnecourt described an overbalanced wheel with
  hinged hammers equally spaced around its rim. The picture displays
  ambiguous perspective. The wheel is actually supposed to be
  perpendicular to the frame and to the horizontal axle. Villard's
  description (translated) is:

                                                           [honnecor.jpg]

    Many a time have skilful workmen tried to contrive a wheel that
    should turn of itself; here is a way to make such a one, by means of
    an uneven number of mallets, or by quicksilver.

  The reference to quicksilver (the liquid element mercury) indicates
  that Villard was familiar with the Bhaskara device, whose design had
  reached Europe by way of Arabia. Villard claimed his machine would be
  useful for sawing wood and raising weights.

  Villard's diagram shows seven hammers, and he insisted on an odd
  (uneven) number of hammers, explaining

    ...there will always be four on the downward side of the wheel and
    only three on the upward side; thus the mallet or bag will always
    fall over to the left as it reaches the top, ad infinitum.

  But, whether the number of hammers is odd or even, such a wheel comes
  to rest very soon. You have to give it a forceful push to make it
  execute even one revolution.

  [overbal1.gif]

  This "overbalanced wheel" idea reappeared in an astounding variety of
  forms over the centuries. We show a better diagram from a later time. A
  system of pegs or stops was required to hold the hammers at a large
  distance from the axle after they flipped over the top and allow them
  to hang freely as they came around the other side. Perhaps the
  rationale was that the balls had more moment (of inertia) on one side
  due to the larger lever arms (even though the principles of torque
  hadn't yet been formalized at this time).

  Even though there are fewer balls on one side of the axle at any given
  position, these have larger lever arms and therefore greater torque. As
  a hammer swings and falls near the top of the wheel, the wheel slows
  during the hammer fall, then gains some speed when the hammer hits its
  peg. There's no net gain in speed, and there's irreversible energy loss
  when hammers hit pegs. If given a push, the wheel will turn jerkily for
  a while. If it were given a very forceful initial push, the hammers
  would assume radial positions and the wheel would turn much more
  smoothly and efficiently, but would gradually lose speed and rotational
  energy because of air drag and bearing friction, just as any spinning
  wheel would.

  We have mostly second-hand accounts of Villard's understanding of the
  principles of this machine. However, I do not think that the folks who
  were fascinated with this idea were unaware of the static balance
  condition of the wheel. I speculate that they supposed the wheel would
  only work after it was manually set in motion, with the hammers giving
  it extra boost as they rapidly flipped across the top, perhaps (they
  may have thought) this was due to some "advantage" obtained from the
  motion of each weight flipping to a position with a larger lever arm.

  [trebu.gif] This flipping action is much like that of a sling that
  gives a person the ability to throw a rock a greater distance, or the
  sling siege engine catapult known as the Trebuchet. Honnecort wrote
  about these machines of war, describing one with an 8x12x12 foot box of
  sand as counterweight (which could weigh 80 tons). Some had arms 50
  feet long and were capable of slinging a 300 pound stone 300 yards.
  This connection to the swinging hammers of Honnecort's wheel and
  Trebuchets is speculation on my part, unsupported by any historical
  study I've seen.

  Even though the sling action of a Trebuchet allows a greater efficiency
  of energy conversion compared to the rigid-arm catapult, the machine
  still puts out no more energy than that of the falling weight that
  drives it. Modern Trebuchets (built by hobbyists) have achieved energy
  conversion efficiencies of greater than 65%.

  The overbalanced wheel idea was re-invented many times over the
  centuries, sometimes in fantastically elaborate variations. None ever
  worked as their inventors intended. But hope never dies. I've seen
  examples made by country blacksmiths and basement tinkerers. The
  classical mechanics necessary to analyze mechanical systems is now well
  known, and when one takes the trouble to do this there's no mystery at
  all why they don't turn forever, and no reason why they should.

  [74]Top
    __________________________________________________________________

Simon Stevin's problem

  [stevin2.jpg] [stevin.gif]
  Simon Stevin (1548-1620) Stevin's ball-ramp experiment,
  the "clootcrans" (chain of balls).

  Flemish mathematician and engineer Simon Stevin (1548-1620) studied the
  principles of mechanisms and machines. He was a forceful critic of much
  of Aristotle's mechanics; his own studies were more in the Archimedian
  tradition.

  One of Stevin's most acclaimed contributions to mechanics was his use
  of a chain of balls (clootcrans) on two inclined ramps as a means for
  developing a method of what we would today call the force
  parallelogram.

  Stevin made use of this ball-chain in a creative way. He forthrightly
  asserted that any notion that the chain might move of its own accord
  was obviously absurd. He gives no reason for this, perhaps assuming
  that none was necessary. Perhaps underlying this was the fact that if
  the chain were to move a distance equal to the separation of the balls
  (in either direction), the new position would be identical to the
  previous one. In effect, no physical change had occurred, therefore it
  won't happen without external influence. If so, this is an early use of
  what is today known as the "principle of virtual work", or sometimes
  "Stevin's principle."

  Taking his starting point as the fact that the chain does not move
  perpetually, Stevin derived the equivalent of the modern law of
  composition of forces. Stevin considered this to be so important that
  this picture of the ball-chain appears on the title page of Stevin's
  book on mechanics, as his "trademark".

  Stevin's achievement was an early example of how one can carefully
  analyze a mechanical system to determine whether (and how) it works.
  Stevin accomplished this long before the vector methods of force
  analysis was understood, and before formulation of conservation of
  energy and the laws of thermodynamics. Stevin also adopted the useful
  tactic of analyzing mechanisms in the "ideal" case where friction is
  assumed absent.

  Some books cite this as Stevin's proof of the impossibility of
  perpetual motion. That was not the case, for Stevin simply assumed the
  impossibility of perpetual motion, at least in this situation.

  [75]Top
    __________________________________________________________________

More on Stevin's principle

  Stevin's principle is useful for problems in equilibrium, and is
  mathematically equivalent to force analysis. In a mechanical system
  where things are free to move, will they? One way to find out is to
  mathematically analyze the sum of forces on each part of the system
  (and also do the same for torques). If they add to zero, the parts
  won't accelerate.

  Stevin's principle allows us to do this in an alternate (yet
  equivalent) way. The method starts by imagining a "virtual
  displacement" of the system, then calculate the net work during this
  "virtual" motion. This is called the "virtual work". If the net virtual
  work is zero, the system is in equilibrium, and will not accelerate. In
  practice the analysis is usually carried out by imagining very small
  displacements.

  [The virtual displacements need not be actual or even likely ones. For
  example, to calculate the tension force in a bridge girder, one may
  imagine the girder being broken or cut and the pieces that are allowed
  to move.]

  This method is particularly useful for systems that are frictionless or
  nearly so. This is ideal for examining perpetual motion machine
  proposals. It's a Gedanken (thought) experiment, but when no working
  model of the machine is supplied, that's all we have to work with. We
  imagine the system to be frictionless (giving the inventor the
  advantage) then if we can show that even with this advantage the
  machine still can't work as claimed, we can consign the proposal to the
  Museum of Unworkable Devices.

  [stevin-r.gif] Before we return to Stevin's problem of the double ramp
  and chain let's first consider the related problem of a double ramp of
  height z and ramp lengths x and y. Let's say that x < y. A weight A is
  on the x ramp and a weight B is on the y ramp. They are connected by a
  rope passing over a pulley at the top.

    Reminder: Work is done on a body when it moves under the action of a
    force. Work is the product of the force component in the direction
    of motion and the distance the body moves.

  Imagine a motion of A up the ramp length x that moves mass A a vertical
  distance z. This causes B to move the same distance x down its ramp, or
  a fraction x/y of the length of that ramp, and therefore a vertical
  distance (x/y)z down. We conclude that for equilibrium these weights
  and distances must satisfy Ay = Bx, or A/B = x/y.

  Be skeptical of any perpetual-motion proposal in which the assumed
  motion causes no change in the position of the center of mass of any
  part of the system.

  Returning to Stevin's problem, using the same ramp, the portion of
  chain on ramp x has length x. The portion on y has length y. The
  weights of chain are in proportion to the lengths, so A/B = x/y
  automatically satisfies the condition for equilibrium. Therefore the
  system will not move on its own initiative. The lower loop of chain
  obviously contributes nothing that would disturb equilibrium.

  The principle of virtual work can be extended to torques, and in modern
  form is:

    If the virtual work done by all external forces acting on a
    particle, a rigid body, or a system of connected rigid bodies with
    ideal (frictionless) connections and supports, is zero for all
    virtual displacements of the system, then the system is in
    equilibrium.

  Let's not dismiss that lower loop so casually, for it is doing
  something very important here. During any virtual (imagined) motion, it
  is supplying new mass to the portion of chain lying on one side of the
  ramp exactly as fast as the portion of chain on the other side of the
  ramp loses mass. It is supplying momentum to one segment of chain at
  the same rate as momentum is lost from the other segment. This,
  however, does nothing to improve the PM machine's chances of working.
  It is a mechanism that keeps the ramp portion of the system unchanged
  over time, even during virtual motion. We will see this process at work
  (virtual work, of course) in many other perpetual machine proposals.

  We may restate Stevin's principle in a form more directly applicable to
  devices claimed to be perpetual motion machines:

    If an assumed (virtual) motion of the machine results in a final
    state of the system (the machine and its interactive environment)
    indistinguishable from its initial state, and zero net work is done
    on the system during this motion (no work in; no work out) then that
    assumed motion will not occur.

  Stevin's principle is a particularly appropriate first step in
  analyzing cyclic and wheel-type machines where a finite rotation of the
  wheel changes nothing but its position. It is particularly useful when
  analyzing those machines for which the inventor's initial casual
  analysis (usually containing a flaw of physics or reasoning) leads us
  to think "That machine will surely turn." It immediately discredits the
  Honnecort wheel and also Stevin's original problem of the ball-chain on
  ramps. Most of the textbook examples of Stevin's principle show only
  cases where the initial and final states of the system are very
  obviously different (things are in different places). But the real
  power of the principle is that it can also be applied to cases where
  the final state "looks just like" the initial state.

  For machines that have a "cyclic" behavior (most do) the analysis must
  be carried out over a complete cycle, for energy may be stored during
  part of a cycle and released during another part.

  Refer back to the double ramp picture. If the chain is imagined to
  undergo a virtual motion carrying each ball to the position occupied by
  the next one, then the initial and final states are identical. Stevin's
  principle then says that the chain will not of itself undergo this
  motion.

  [76]Top.
    __________________________________________________________________

  Friction is never the only reason why a perpetual motion machine won't
  work. Remove the friction and it still won't work as the inventor
  intended.

Friction and idealizations.

  To assert that a device "Will not work because of friction" diverts our
  attention from far more fundamental flaws of the proposal. Friction is
  ever-present in nature. Yet, in analyzing PM proposals, it is useful to
  assume frictionless components, for in all non-trivial PM proposals,
  friction is never the sole problem. Remove all dissipative process such
  as friction, use idealized components, and at best the devices will be
  only our type (1). They cycle uselessly forever without additional
  input or output work.

  Frictionless components do not violate fundamental macroscopic
  principles of physics. If removal of all dissipative processes results
  in a perpetual motion device of type (1), you know you've probably done
  the analysis correctly, making no blunders.

  But other idealizations do violate fundamental macroscopic classical
  physics principles. Remember that we are speaking now of the
  macroscopic (large scale) physics processes, not those at the
  microscopic scale of atoms or smaller.
    * Massless components that are capable of exerting forces on other
      components would violate Newton's second law.
    * Components that exert forces without accompanying reaction forces
      would violate Newton's third law.
    * Perfectly rigid bodies capable of exerting forces on other such
      bodies violate Newton's laws also. All matter can be compressed or
      stretched, giving rise to elastic forces. If bodies were perfectly
      rigid we'd have infinite forces acting for infinitesimal times. We
      cannot assume such things in the real world.
    * A material macroscopic body cannot be observed in two places
      simultaneously.
    * No information can travel between two separated points
      instantaneously. This is another reason why perfectly rigid bodies
      can't exist. If you pushed on one end of a perfectly rigid stick,
      the other end would move instantaneously. But that's not possible,
      for it would mean the other end received information about the push
      instantaneously.
    * Mass cannot vanish from one place and time and reappear at another
      place and time.

  [77]Top.
    __________________________________________________________________

Tapping quantum weirdness

                     Nature abhors macroscopic perpetual motion. — D.E.S.

  Nature's prohibitions listed in the last section apply to macroscopic
  (large scale) physical objects. Is it possible that these can be
  violated on the microscopic (small scale) world of atoms and smaller
  entities? Certain currently popular speculative theoretical ideas
  suggest that.

  Nature does not prohibit perpetual motion. No laws of nature would be
  violated by something existing forever in a non-zero energy state.
  Presumably undisturbed atoms can do that. Whatever is "going on" within
  an atom continues undiminished forever if the atom is left undisturbed.
  What nature does seem to prohibit is a system that produces useful work
  in amount greater than its energy input.

  The perpetual motion machines that seem to work best are those that
  turn out to be fraudulent. — D.E.S.

  In these pages I have indeed neglected current speculations in physics
  such as string theory, vacuum energy, black holes, wormholes, dark
  energy, dark matter, parallel universes, etc. I'm probably not
  sufficiently knowledgeable about these matters to discuss them
  effectively. I do note that many of these concepts are "virtual"
  entities that are part of the mathematical theory, but are not directly
  observable. And when these do have observable (experimentally
  measurable) consequences, nature seems to prohibit them being converted
  to continuous output of useful work on a macroscopic scale. So our
  hopes of making a macroscopic perpetual motion device based on them is
  apparently futile. The more we learn about nature, the more evidence we
  accumulate that "Nature abhors macroscopic perpetual motion." A very
  interesting book discussing these matters is "How to Build a Time
  Machine" by Paul Davies. It is now out in paperback from Penguin Books
  at $13.00. The cover blurb says "A quick...lucid romp [through]
  wormholes, naked singularities, alternative universe, cosmic strings,
  exotic matter, negative energy, imaginary mass, gravitational time
  dilation, rising entropy and falling information" —San Francisco
  Chronicle. Davies' book concludes that nature does have taboos: "No
  time machines, no perpetual motion machines, no naked singularities!
  Etc."

  [78]Top.
    __________________________________________________________________

  Shouldn't all perpetual motion machines come with a limited warranty? —
  D.E.S.

What about "free energy"?

  When analyzing PM proposals, one must watch out for "hidden" energy
  sources. If the chain of the Stevin machine consisted of interlinked
  cylindrical rollers, it might be made to move if there were a small
  battery and a motor within each cylinder. Many classic perpetual motion
  machine scams are done this way. But in this case, the initial and
  final states are not identical, for the state of the batteries changes
  as power is drawn from them. Some of the early fraudulent demos of PM
  machines may well have been driven by hidden internal stored energy,
  allowing a massive, well-balanced and low friction wheel to turn for a
  very long time before slowing perceptibly.

  "Free-energy" enthusiasts claim that if a machine were tapping some
  invisible energy source that fills all of space, that energy would,
  like the hidden motors, keep the machine going, even though we could
  not detect the free energy source by any other experimental means. In
  effect, the machine itself would be the "free energy detector". They
  remind us that physicists once ridiculed the idea of energy stored in
  atoms. Yes, they did, as these quotes indicate.

    There is no likelihood man can ever tap the power of the atom. The
    glib supposition of utilizing atomic energy when our coal has run
    out is a completely unscientific Utopian dream, a childish
    bug-a-boo. Nature has introduced a few fool-proof devices into the
    great majority of elements that constitute the bulk of the world,
    and they have no energy to give up in the process of disintegration.

    - Robert A. Millikan (1863-1953) [1928 speech to the Chemists' Club
    (New York)]

    ...any one who expects a source of power from the transformation of
    these atoms is talking moonshine...

    - Ernest Rutherford (1871-1937) [1933]

  So, do the "free-energy" proponents have a valid point here? Are they
  justified in devoting their time to seeking a "free-energy" or
  "over-unity" systems? Should mainstream scientists take up such
  research to solve our energy problems? I think not. Scientists
  generally pursue something only when there's clear evidence pointing to
  a need for extending, clarifying or otherwise changing physical theory.
  So far, not one scrap of credible or even suggestive evidence for the
  existence of this "free-energy" has been seen. To return to the
  comparison with atomic energy, the initial skepticism of Millikan,
  Rutherford, and Einstein was well justified. But they changed their
  opinions as new evidence came in. Their initial skepticism did not in
  any way retard our progress toward discovery and utilization of atomic
  energy. My hunch is that if there is anything like "free-energy"
  anywhere in the universe, it will not be discovered by the kind of
  people now making wild and unfounded claims about it, nor by the
  methods they are using to try to tap it. It helps to have evidence for,
  and know something about, a source of energy before one attempts to
  figure out how to utilize it. All the ingenuity in the world can't
  extract energy from something that isn't there, has no energy to
  extract, or no way to convert it to useful work.

  The production of useful work is strictly limited by the laws of
  thermodynamics, but the production of useless work seems to be
  unlimited.
     —Donald Simanek

  What about possible "accidental" discovery of free energy by some
  basement PM tinkerer? Weren't X-rays discovered accidentally, when no
  one even suspected their existence and certainly had no idea what they
  were? Yes, that's one of the (very few) examples of a truly accidental
  important discovery in physics. Quite a number of people stumbled on
  evidence for X-rays before Röntgen but failed to follow up with
  experiments to see what was going on. Anti-serendipity? But during that
  same period of history we have the interesting phenomena of other
  people "discovering" things that did not exist, such as N-rays, and
  later M-rays (mitogenetic radiation). So in which category will "free
  energy" fall, if and when someone claims to have found experimental
  evidence for it? Only time will tell.

  On the whole, scientific discoveries, even accidental ones, are most
  likely to be made, investigated, and exploited by folks who have a very
  good understanding of the relevant principles of existing science.
  Ignorance of well established science causes many sincere and dedicated
  people to waste lives and careers chasing moonbeams. The sincere PM
  proposals of the past illustrate the fact that their inventors did not
  have sufficient understanding. Many of them believed that such
  understanding wasn't necessary, or they rejected it out of hand.

  [79]Top
    __________________________________________________________________

Buoyancy motor #1

  [buoy1.gif] John Phin describes this one in his classic book Seven
  Follies of Science (Van Nostrand, 1906), attributing it to a
  correspondent named "Power".

    A J-shaped tube A, Fig. 14, is open at both ends but tapers at the
    lower end, as shown. A well-greased cotton rope C passes over the
    wheel B and through the small opening of the tube with little or no
    friction, and also without leakage. The tube is then filled with
    water. The rope above the line WX balances over the pulley, and so
    does that below the line YZ. The rope in the tube between these
    lines is lifted by the water, while the rope on the other side of
    the pulley between these lines is pulled downward by gravity.

  Phin says that the "inventor offers this device as a kind of puzzle
  rather than as a sober attempt to solve the famous problem," and Phin
  concludes by asking why it will not work.

  As usual, Phin misses the point (and the fun) of the challenge in his
  analysis of this puzzle. He trots out the usual lame dismissals such as
  bearing friction, work required to bend the rope, and friction of the
  rope at the water-seals, then, supposing the case is closed, moves on
  to something else.

  [buoy2.gif] I rephrase the challenge, and show a simpler picture. The
  smooth rope passes through a container of liquid, with an impermeable
  frictionless seal in the bottom.

  I also set a ground rule to deflect irrelevant responses: Assume
  everything is perfect. No friction, leakless seals, perfectly flexible
  impermeable rope, no viscous drag between rope and liquid. Even with
  these ideal conditions we can easily and simply show that this machine
  will not work as claimed. Why did the inventor of this problem think it
  should seduce us into thinking it might work? It's his phrase "lifted
  by the water". He is, of course referring to the buoyant force of
  Archimedes' principle: "A body immersed in liquid experiences and
  upward buoyant force equal to the weight of the displaced liquid." This
  principle is found in every elementary physics textbook, but seldom
  understood by students. They use it blindly, not knowing why it is true
  nor under what conditions it is true, and they haven't paid attention
  to how it is derived.

  The claim is that the upward buoyant force on the portion of the rope
  in the liquid causes the rope to move upward there. This claim is
  false. Why?

  Answer:

  There is no buoyant force on the rope. This deception is a based on a
  common misunderstanding of Archimedes' principle. The principle
  requires that the submerged body have liquid beneath it so that the net
  force due to the liquid acting on the body has nonzero upward
  component. The principle also works if a body is totally immersed, with
  water above and below, or floating, with water only below. After all,
  what is the source of the buoyant force? It is the pressure difference
  between upper and lower surfaces. Consider a totally immersed cylinder
  with its axis vertical (very appropriate in this case). Pressure on the
  sides of the cylinder provides only horizontal forces that also add to
  zero, and more importantly, have no vertical components. Only forces
  due to pressure on top and bottom surfaces have vertical components.
  The pressure on the bottom is greater than that on top by amount r gh,
  where r  is the liquid density. So there's a net upward force on the
  cylinder.

  In this PM puzzle, there's no liquid above or below the rope capable of
  providing an upward component of force. All the forces on the rope due
  to the liquid are strictly horizontal, and because these forces are
  symmetrically distributed around the circumference of the rope, they
  add to zero.

  An astute correspondent notes that my argument here lacks generality.
  He proposes a variant in which the rope passes through the liquid at an
  angle, say making an angle of 45° to the vertical. Now there is liquid
  above and below the rope. And if there's now a buoyant force on the
  rope, it surely has an upward component in the direction of the rope,
  and therefore this version of the machine should work. Why doesn't it?

  Solution left as exercise for the student. The solution might require
  calculus. Here's a helpful hint. That Buoyant force mentioned in
  Archimedes' principle is not some new "magic" force that arises when a
  body is immersed. The buoyant force is a resultant (sum) of pressure
  forces acting on the immersed body. Archimedes' principle is merely an
  expression of a useful relation between the densities of the bodies
  involved, resulting from geometric laws and the fact that pressure
  exerts force normal to a surface.

  [80]Top
    __________________________________________________________________

Buoyancy motor #2

  [buoyant.gif] Here's yet another PM machine claiming support in
  Archimedes' principle. Poor misunderstood Archie really takes a
  beating.

  Claim:

  A wheel in the form of a perfect sphere or cylinder rotates about a
  frictionless horizontal shaft. The left side is in a chamber filled
  with water, perfect (frictionless and leak-proof) seals around the
  rotating wheel prevent the liquid from escaping. The left side of the
  wheel therefore experiences an upward buoyant force due to the liquid
  it displaces. So that side will rise, and the wheel rotates clockwise.

  Answer:

  All forces exerted by the liquid upon the circumference of the wheel
  are normal to the wheel's surface, and therefore pass through the
  wheel's rotation axis. All of these forces have zero lever arm with
  respect to this axis. The liquid therefore provides no torque about the
  wheel axis and the wheel won't turn.

  Be skeptical of any cyclic perpetual-motion proposal that can be
  operated equally well in either direction.

  Stevin's principle of virtual work demolishes this PM device neatly. We
  know the wheel will have no tendency to rotate because if we imagine a
  virtual displacement of the wheel through any angle, the system would
  still be just the way it was before, with no change in its energy and
  no change in configuration. No work is done in the process.

  [torus2.gif] Richard G. Clegg's [81]Perpetual Motion Page has a clever
  variant of this buoyant motor. Instead of a wheel it has a torus
  (doughnut-shaped ring) passing through two seals separating two
  chambers having liquids of different density. There is no axle. One
  half of the ring is surrounded by liquid, inside and outside. The seals
  are of course frictionless and leak-proof. There's no axle to provide
  reaction forces. Here the forces on the ring due to pressure do have
  upward components. Why won't this one work? [Picture used with
  permission of Richard G. Clegg.]

  Answer left as exercise for the student.

  [82]Top
    __________________________________________________________________

Buoyancy motor #3

  [float-pm.gif] This perpetual motion machine probably dates from the
  mid 1800's. The main drum is filled with a liquid. In it are round
  chambers filled with air (or a vacuum) and connected by rods to the
  weights outside. The rods slide in frictionless leak-proof seals, of
  course. As with many such proposed mechanisms, this picture is more
  complicated than necessary to illustrate the principle upon which it is
  supposed to work. The drawings below show just one weight and one air
  chamber immersed in liquid.

  When in position 1, the buoyancy of the lower sphere is enough to lift
  the weight to its highest position. If the drum is now pushed so it
  moves counter clockwise, the weight stays at this large radial distance
  at least until it has rotated 90°.

                              [hydraul3.gif]

  During the next quarter turn the weight has a large lever arm. At the
  end of this quarter turn, position 3, the air chamber rises to the top
  of the drum, and the weight is now is at its smallest radial distance,
  (and smallest lever arm) where it stays for the next quarter turn.
  During the last quarter turn the air chamber's buoyancy causes the
  weight to rise until it is at its largest radius.

  Since the torque during the second quarter turn is greater than during
  the third quarter turn, the wheel will gain more energy there than it
  needs to move upward during the fourth quarter-turn.

  The principles that are supposed to make this thing work allow the
  machine to be started by a push in either direction, and it would work
  just as well clockwise as counterclockwise. That's a bit suspicious,
  isn't it? Also, if we imagine motion of this wheel through a full
  cycle, the final and initial states are indistinguishable, so Stevin's
  principle tells us that it won't turn. Yet we'd still like to analyze
  the details to see exactly where the inventor went astray.

  We'll give you a grant to buy frictionless bearings, a liquid with zero
  viscosity, and leak-proof frictionless seals for the movable rods. With
  all of this advantage, why will it still not work?

  [83]Solution by Ben Mitch.

  [84]Top
    __________________________________________________________________

Buoyancy motor #4

  Here's a new addition to our museum, contributed by Dave Carvell. This
  one has some innovative details to challenge your understanding of
  physics.

  [tubes2c.gif] The sealed container has two vertical tubes. The right
  one contains a liquid (cyan) such as water, and a very light ball
  (red), much lighter than the liquid. As usual we'll let you use a
  liquid with zero viscosity. (We are generous about these details that
  don't matter anyway.)

  Two "gates" G1 and G2 are made like iris diaphragms that can open and
  close quickly. They are, of course, watertight when closed.

  Now we all know that when a light object, like a cork, is underwater,
  then released, it pops to the surface and can even pop above the
  surface. We take advantage of that fact. Our machine, with its
  viscosity-free liquid, should allow even greater speed at the top. The
  machine is started with the ball at the bottom. As it rises, a
  high-tech sensor quickly opens gate G1 to let it through, closing the
  gate immediately, and then opening gate G2 in time for the ball to pass
  through.

  Since one of the gates is closed at all times the water levels are
  maintained. The ball pops above the surface with some momentum, and the
  curved top of the apparatus deflects it to the other tube, where it
  falls, gaining speed and momentum in the fall, enough so that it goes
  under the liquid surface there and is bumped over into the right tube,
  where, of course, it begins to rise. This should go on forever, gaining
  speed each cycle.

  Surface tension and viscosity present real problems here. But before we
  go to the trouble to find a perfect fluid for this device, we should
  look for even more fundamental flaws.

  [85]Solution

  [86]Top
    __________________________________________________________________

Capillary motor

  [capillar.gif] Claim:

  This is one of my favorite PM proposals for challenging student
  understanding. Most students know that liquids will rise in a very
  narrow tube, the process being called "capillary action". Suppose we
  have such a tube capable of lifting the liquid to a height h. Now lower
  the tube to a height less than h. Or make a hole in its side below the
  top of the liquid column. The liquid, trying to rise to height h will
  then spill out the top of the tube, where a very tiny waterwheel can
  capture its energy as it falls.

  Answer:

  [captube.gif]

  This is only likely to fool people who haven't considered why capillary
  action occurs. The usual textbook diagram is shown at the left. Surface
  tension acts at the liquid surface where it contacts the walls of the
  tube. These intermolecular forces between liquid and glass are greater
  than those between the liquid molecules themselves. This gives rise to
  a curved "meniscus" shape of the upper liquid surface. The forces
  around this interface act at an angle with a significant upward
  component that can hold the water column in static equilibrium.

  The pressure of the water at the surface of the reservoir is
  atmospheric pressure, both outside and inside the capillary tube. This
  is due to Pascal's principle that the pressure at all points at a given
  height within a liquid is the same. Also, by the same principle, the
  pressure within the capillary tube, just below the meniscus, is less
  than atmospheric pressure by amount rgh. This accounts for the pressure
  difference across the meniscus that in turn accounts for its shape. The
  atmosphere is pushing down on the meniscus, but molecular adhesion
  forces around its edge oppose that. It acts like an elastic sheet
  restrained at its edges.

  If one now gradually lowers the tube, the supported column of liquid
  remains the same length. The top of the tube moves down to meet the
  meniscus. Continue to lower the tube and finally the liquid column
  reaches the top of the tube. But, remember, the pressure just below the
  meniscus is still lower than atmospheric pressure, so the meniscus
  still bulges downward. It does not spill over the top of the tube. The
  liquid surface always contacts the upper rim of the tube, and as the
  tube is lowered even more, the meniscus follows it down.

                                                          [capillar3.gif]

  This picture shows situations you might have imagined possible. The
  version shown in the second figure, with a hole in the side, is easily
  discredited. The hole must be smaller than the tube diameter, so it,
  too will exhibit surface tension forces. The pressure just inside this
  hole is still lower than atmospheric pressure, so the water will bulge
  inward, not outward, and no liquid will pass through it.

  Pressure increases downward in a liquid, by the law ρgh where ρ is the
  liquid density. The pressure at the liquid surface outside the
  capillary tube is atmospheric. So the pressure within the tube must
  decrease with height up to the meniscus. It's the pressure difference
  across the meniscus that is responsible for its curved shape. The
  second figure depicts an outcome that just can't happen.

  [87]Top
    __________________________________________________________________

Capillary wheels

                                                            [2wheels.gif]

  Claim:

  This idea appeared in the correspondence column of the April 22, 1911
  issue of Scientific American. The editor invited readers to "search out
  the fallacy of this ingenious device."

  Imagine two very carefully machined wheels with parallel axes on
  frictionless bearings. They are partly immersed in a liquid. There's a
  very narrow space between the flat portions of the wheels, causing
  liquid to be drawn up between, by capillary action. The weight of this
  sheet of liquid exerts downward forces on both wheels; therefore they
  should rotate in opposite directions as shown by the arrows. Since the
  force is small, the speed will be low also, giving the capillary column
  plenty of time to rise to compensate for this motion, maintaining a
  steady height.

  [capbelt.gif]

  As usual, ignore friction and viscosity. The column of liquid is
  certainly being supported by an upward force provided by the wheels.
  Newton's third law requires that the column of liquid exerts a downward
  force on the wheels. This surely provides a torque on both wheels. So
  why don't they move?

  Another version, using pulleys and belts is shown at the left. The
  principle is the same, so we expect this to work just as well as the
  wheel version.

  This is another case where indistinguishable initial and final states
  and Stevin's principle should have aborted this project at the
  conceptual stage.

  [88]Answer and discussion.

  [89]Top
    __________________________________________________________________

George Sinclair's siphon.

  [sinclair.gif] This curious device appears in a 1669 book on pneumatics
  (in Latin) by philosophy professor George Sinclair of Glasgow
  University. Dircks mentions it in his 1870 book Perpetuum Mobile (p.
  42) from which we took this picture.

  Apparently the upper bulb has reduced pressure of air within it,
  sustaining the liquid drawn up from the dish. One end of a siphon
  transfers liquid from this bulb up through the bent rod and back to the
  dish. This loss of liquid from the bulb is replaced by more liquid
  drawn from the dish, due to the low air pressure in the bulb. Result:
  an endless circulation of liquid. A little water wheel might be run by
  the water exiting from the siphon into the dish. Well, maybe not.

  Sinclair must have thought this device pretty neat, for he devoted 18
  pages to discussion of its merits. You, dear reader, should easily
  demolish it in a few paragraphs.

  [90]Answer and discussion.

  [91]Top
    __________________________________________________________________

Bob Schadewald's gravity engine.

  [sge-ele4.gif]
    __________________________________________________________________

  Artist's conception of the gravity engine power station. The engine is
  an overbalanced wheel or off-axis weight with (of course) frictionless
  bearings. Based on the assumption that the universal gravitational
  constant is continually decreasing this engine exploits the small
  energy that can be gained from this during each revolution. In keeping
  with the philosophy of the engine itself, power is transferred to the
  electric generator by a linkage of devious pulleys and belts. [Drawing
  © 1992 by Donald E. Simanek.]
    __________________________________________________________________

  First, let's be very clear that Bob's [92]BS Gravity Engine is a
  parody, a joke. His intent was to tease, and amuse, and to tweak
  physicists and engineers whose understanding of physics was shaky. It
  was a challenge to readers to show conclusively whether or not it could
  work, given the "decreasing gravity" assumption. He was careful never
  to fully answer that question or to explain the joke.

  [sge2.gif]

    The suggestion that the universal gravitational constant might be
    declining came out of speculative theoretical work of Paul A. M.
    Dirac. In 1937 he suggested that the universal gravitational
    constant G might be weakening, proportional to the age of the
    universe. He even predicted that in 10 billion years it might be
    only half what it is today. Since then the notion that fundamental
    constants, including the speed of light, might change over time has
    fascinated speculative theorists. It has also fascinated new-age
    wackos, who shamelessly adapt and pervert the idea to fit their own
    agendas.

  Obviously the BS engine falls into my class (2) and possibly (4).

  Stevin's principle does not kill this proposal, for the initial and
  final states of the system (including its environment) after each cycle
  are not identical. This wheel would operate equally well in either
  direction, however, that is always suspicious.

  Scott Morris discussed some PM machines in OMNI magazine in 1990 (July,
  p. 98 and 99; August p. ?), and quotes Bob Schadewald as saying "My
  description is a subtle deception. The velocity of the moving weight
  will never exceed what it was when it passed the bottom, dead center,
  the first time, even if there is no friction. The weight may pick up
  speed at the top, but never at the bottom, so there is never any real
  speedup in the wheel."

  How does Bob arrive at that conclusion? Can this unexpected result be
  justified by elementary physics? And why does Bob say "the weight may
  pick up speed at the top, but never at the bottom"?

  [93]Answer and discussion.

  [94]Top
    __________________________________________________________________

Simanek's bouncing ball engine

  This PM proposal works just as well at Bob Schadewald's Gravity Engine
  (SGE) and it may be easier to analyze. Doing so might shed some light
  on the principles behind the SGE.

  Bob cast his SGE in the form of a wheel. This introduces the feature of
  rotation that is a "red herring" for some people. They think that the
  paradox somehow depends on rotation or requires consideration of
  centrifugal effects. It doesn't, as this non-rotating bouncing ball
  engine illustrates.

                               [lounge4.gif]

                    Inventor reads by light powered by
             electricity provided by the ceiling transducer of
              a bouncing ball engine. He's wearing earplugs.

  A ball bounces up and down between floor and ceiling, both rigid and
  massive. The bounces are assumed elastic, that is, the ball's velocity
  after impact is the same as before impact, but with reversed direction.

  Now imagine that the gravitational constant g is slowly but steadily
  decreasing. The ball is released at rest from the ceiling. The ball
  attains a certain speed when it reaches the floor, and rebounds with
  that same speed. But since g is now smaller, the ball still has a small
  velocity when it hits the ceiling. Clearly this means that on
  completion of this ceiling-to-floor-to-ceiling cycle it has gained a
  small amount of kinetic energy, which we could extract with a slightly
  inelastic ceiling panel. The panel would steal just that extra amount
  of energy, bringing the ball to rest there momentarily. The ball would
  then start the next cycle with zero speed, as in the previous cycle.
  The gravitational force, though slightly smaller than before, would
  cause the ball to fall to the floor and bounce back to the ceiling,
  where we again steal the excess energy gained in this cycle, and so on
  forever, or until gravity runs out, whichever comes first.

  The assumptions of perfectly elastic impact and infinite mass floor are
  no more unreasonable in posing this apparent paradox than the
  assumption of frictionless bearings in the wheel. Given these
  assumptions we still ought to be able to analyze the machine and show
  whether it could work as claimed.

  [95]Answer and discussion.
  [96]Top
    __________________________________________________________________

The Gravity shield engine

  [gravshld.gif] Claim:

  This proposal is at least a century old. Classic simplicity! A wheel
  has a frictionless axle. Now just insert a gravity shield under one
  side, making that side lighter and this will initiate and maintain
  rotation. Indeed, you'd better extract energy from it continually, or
  put a brake on it, or it will spin so fast it will tear itself apart.

  I've often seen this without reference to its inventor. If anyone knows
  who the inventor is, please let me know. Nicola Tesla described it, in
  his article [97]"The Problem of Increasing Human Energy" in Century
  Illustrated Magazine, June 1900.

    It is possible, and even probable, that there will be, in time,
    other resources of energy opened up, of which we have no knowledge
    now. We may even find ways of applying forces such as magnetism or
    gravity for driving machinery without using any other means. Such
    realizations, though highly improbable, are not impossible. An
    example will best convey an idea of what we can hope to attain and
    what we can never attain. Imagine a disk of some homogeneous
    material turned perfectly true and arranged to turn in frictionless
    bearings on a horizontal shaft above the ground. This disk, being
    under the above conditions perfectly balanced, would rest in any
    position. Now, it is possible that we may learn how to make such a
    disk rotate continuously and perform work by the force of gravity
    without any further effort on our part; but it is perfectly
    impossible for the disk to turn and to do work without any force
    from the outside. If it could do so, it would be what is designated
    scientifically as a "perpetuum mobile," a machine creating its own
    motive power. To make the disk rotate by the force of gravity we
    have only to invent a screen against this force. By such a screen we
    could prevent this force from acting on one half of the disk, and
    the rotation of the latter would follow. At least, we cannot deny
    such a possibility until we know exactly the nature of the force of
    gravity. Suppose that this force were due to a movement comparable
    to that of a stream of air passing from above toward the center of
    the earth. The effect of such a stream upon both halves of the disk
    would be equal, and the latter would not rotate ordinarily; but if
    one half should be guarded by a plate arresting the movement, then
    it would turn.

  Critics will be quick to observe that if one imagines a virtual
  rotation through a small angle, the wheel is physically the same as
  before. The small portion at the bottom that was in the gravitational
  field becomes weightless over the gravity shield, but at the same time
  an equal segment of the wheel moves from weightless condition back into
  the gravitational field. They therefore argue that nothing has changed,
  and there is no reason there should be such motion. This is a nice
  application of Stevin's principle of virtual work.

  The unknown inventor might argue thusly: Remove the gravity shield.
  Imagine an equivalent: a half-wheel. It would rotate under the action
  of gravity and then continue to swing like a pendulum. You can hardly
  deny that if one half of the wheel suddenly had no gravitational force
  upon it, the other half would move due to the unbalanced torque.

  [gravshl2.gif] This suggests a better design. Don't use a wheel. Use an
  unbalanced weight as in the SGE (see previous item). Start the machine
  with the weight at the top of its range. Give it a slight nudge toward
  the unshielded side, and it will fall, gaining kinetic energy. This
  kinetic energy at the bottom remains unchanged during its upward motion
  over the shield, and is still there when the weight reaches the top,
  carrying it into the unshielded side where it picks up still more
  energy, and so on forever. What prevents that?

  There's always the possibility that you may assume some part of the
  machine that is itself physically impossible. If one too readily grants
  its possibility, much time can be wasted analyzing the other parts of
  the machine. Here the suspect part is the gravity shield. Can we simply
  and conclusively show that a gravity shield is or is not possible? Can
  we show that its very existence would violate some fundamental law?

  This puzzle doesn't require a perfect shield. A shield that reduces the
  gravitational force by only a few percent would seem to meet the
  requirements of a perpetual motion machine. We need to show, by simple
  physics that (1) the very existence of such a shield would violate
  fundamental laws of physics, or (2) even with such a shield, the wheel
  would not turn perpetually and would not gain speed or (3) some
  fundamental law of physics is wrong, and so is Stevin's principle and
  the laws of thermodynamics.

  The rationale for this wheel says that it will only gain speed in one
  direction. If turned in the other direction it would lose speed. This
  may be a clue. Stevin's principle demolishes the version with a uniform
  wheel, for the initial and final states of the system and environment
  are identical for any virtual displacement of the wheel. Therefore the
  wheel cannot move on its own. So why did we mistakenly think that it
  should turn by itself? Stevin's principle also discredits the eccentric
  weight version, for a virtual displacement of one revolution returns
  the wheel an identical state. But that doesn't help us understand
  what's going on during each cycle.

  [98]Discussion and answer.

  [99]Top
    __________________________________________________________________

The Classic magnetic shield engine

  [magpm.gif] A reader informs us that a device of this sort was given as
  an extra credit homework problem by an MIT professor back in 1985.
  Chris Cheng, a high school student from Sydney, Australia, sent us a
  simple version, from which this one evolved through a process of
  tinkering.

  How it's supposed to work.

  Magnetic shielding materials are available. They aren't perfect
  shields, but for the purposes of this motor they don't need to be
  perfect.

  A freely rotatable armature in the center consists of a permanent
  magnet partly covered with a magnetic shield (solid black). The shield
  has openings at the right, near the poles. An outer ring has magnets in
  a radial array with their north poles inside, firmly fastened to a
  rigid frame. These magnets are long, so the south poles are at a
  considerably greater radius than the north poles. The magnetic field
  from a magnet pole decreases in strength with distance.

  The shield apertures permit each armature pole to "see" only a couple
  of the magnets of the outer ring. Each armature pole is affected
  primarily by the north poles of the ring, those being nearest.
  Therefore, in the position shown in the picture, the N pole of the
  armature is repelled, experiencing a force to the left. The S pole of
  the armature is attracted, experiencing a force to the right. These two
  forces make a couple, which rotates the armature clockwise.

  Classic simplicity! If you wanted to improve it, those outer magnets
  could be swung up or down so they were in a cylindrical array of
  magnets with their axes parallel. Then a similar armature could be
  placed in the plane of the S poles, operating on the same axle as the
  armature in the plane of the N poles. This should double the power
  output!

  We caution the reader that this machine has details that could be
  subtle and difficult to analyze in detail. Gauss's and Stokes' laws in
  vector calculus form may be required for a full analysis. However, this
  machine has a simple and fundamental flaw that can be appreciated even
  at the introductory physics level.

  [100]Answer and discussion.

  [101]Top
    __________________________________________________________________

  [lhupedu1.gif] Re: Answers left as exercise for the student. Send your
  answers to the address shown at the right. The earliest good answer(s)
  that arrive may be posted here, with credit to author. I will post (at
  my discretion) answers that are simple to explain, clear, correct,
  perceptive, and that stimulate thinking and further discussion. Posted
  answers, whether written by me or by others, do not always represent
  the final word on a given proposal. On several occasions perceptive
  readers have noticed things we missed, or suggested simpler ways to
  explain something. So don't hesitate to skeptically rethink given
  "answers".

  While I welcome submission of new or innovative perpetual motion
  puzzles, I assume no obligation to respond in detail to all of them. In
  particular, I cannot be expected to analyze vague proposals, overly and
  unnecessarily complicated designs, nor ideas that are simply variations
  of classics found in the literature. I've already received proposals
  that fail for the same reasons already discussed above, indicating that
  the person proposing the idea hadn't fully understood this document.
  Also, I choose not to include devices that would require advanced
  mathematics or physics for detailed analysis. I don't like to post
  puzzles unless I am reasonably confident what the flaw is, and that the
  flaw can be explained using elementary physics principles.

  To those inventors whose creations I choose not to include in the
  museum collection, I offer this comment and consolation:

                               [forever.gif]

    "It may be perpetual motion, but it will take forever to test it."
                        Cartoon by Donald Simanek.
    __________________________________________________________________

  [102]Top

Links

    * [103]Hans-Peter Gramatke has an excellent site (in German) covering
      everything you ever wanted to know about Perpetual Motion Machines.
      He also has a large portion of it in an [104]English version.
      Hans-Peter has been an invaluable source of information to me while
      expanding my site.
    * Kevin Kilty's [105]Perpetual Motion web page has some nice pictures
      and explanations. Kevin has been most helpful to me in discussions
      of the finer points of PMM.
    * The [106]Scientific American Supplement has seven lengthy articles
      about perpetual motion machines, described in detail, with nice
      engravings, and wry sarcasm as well. This is a free download from
      Google.
    * [107]Eric's history of Perpetual Motion and Free energy Machines.
      Many other useful links are on this page.
    * Bob Jenkins' [108]Perpetual Motion Machines briefly describes some
      PMM not found elsewhere on the Internet.
    * [109]"PERPETUAL MOTION" SEEKERS. THEIR FASCINATING BUT HOPELESS
      PURSUIT. With Illustrations of Machines that have been Invented
      Recently. Harmsworth's Magazine - September 1898
    __________________________________________________________________

  [110]Top

References and additional reading:

  When I first became interested in this subject, most of these
  references were rare, hard to find books. I was fortunate to have
  copies of them. Now [2012] many of them are available as free ebooks.
  Others are available in expensive reprint editions. There's now no
  excuse for any hopeful perpetual motion machine inventor to be ignorant
  of the long history of this subject.

   1. Angrist, Stanley W. "Perpetual Motion Machines" in Scientific
      American, Jan 1968. This article is also in a Sci. Amer. reprint
      book.
   2. Angrist, Stanley W. and Loren G. Hepler. Order and Chaos. Basic
      Books, 1967. [QC311.A5]
   3. Collins, John. Perpetual Motion: An Ancient Mystery Solved? Permo
      Publications, 1997, 2005. A history of Johann Bessler, compiled
      from original sources.
   4. Dircks, Henry. (1806-1873) [111]Perpetuum Mobile, or the search for
      self-motive power during the 17th 18th and 19th centuries. London,
      E. & F. Spon, 16 Bucklersbury, 1861. Rogers and Hall Co., 1916.
   5. Dircks, Henry. (1806-1873) [112]Perpetuum Mobile, or the history of
      the search for self-motive power from the 13th to the 19th century.
      London, E. & F. Spon, 48 Charing Cross, 1870.
   6. Dircks, Henry. (1806-1873) [113]Scientific Studies or Practical, in
      Contrast With Chimerical Pursuits, Exemplified in Two Popular
      Lectures. I. The Life of Edward Somerset, Second Marquis of
      Worcester, Inventor of the Steam Engine. II. Chimeras of Science:
      Astrology, Alchemy, Squaring the Circle, Perpetuum Mobile, Etc.
      London, E. & F. N. Spon, 48 Charing Cross, S. W. 1869.
   7. Gardner, Martin [114]Fads and Fallacies in the Name of Science.
      Dover, 1952, 1957. This is a classic. This book has no chapter on
      perpetual motion, but Gardner's comments on the psychology of
      pseudoscientists and cranks apply equally well to many perpetual
      motionists. See the next reference for his comments on perpetual
      motion.
   8. Gardner, Martin. Perpetual Motion: Illusion and Reality, Foote
      Prints, (house magazine of Foote Mineral Co., Exton, Pennsylvania.)
      Vol. 47, No. 2, 1984, p. 21-35.
   9. Herring, Daniel Webster (1850-1938). [115]Foibles and Fallacies of
      Science. Van Nostrand, 1924.
  10. Hiscox, Gardner D., M.E. Mechanical Appliances and Novelties of
      Construction. Normal W. Henley Publ. Co., 1927. [116]Chapter 23,
      available online, is a marvelous resource of about 60 failed
      mechanical devices, with pictures. Inventors' names, dates, and
      patent numbers are usually not given, nor does this source give
      reasons why the devices don't work. Hiscox's preamble suggests that
      scientific opinion is divided on the possibility of perpetual
      motion. But his description of many of these devices reveals that
      he has no doubt about their impossibility, and he seems to be
      saying "Of course you can see why these obviously won't work, so I
      don't need to spell it out." Alas, that is not at all obvious to
      many inventors, even today, who peddle minor variations of these
      old and discredited ideas, fully confident that they must work. If
      you have just invented a seemingly marvelous perpetual motion
      machine, you'd better look here to see whether it has been done
      before. If it has, you can be sure it doesn't work.
  11. Jastrow, Joseph. [117]The Story of Human Error. D. Appleton-Century
      Company, 1936. Chapter on "Error in Physics," by W. F. G. Swann.
      Books for Libraries.
  12. Moore, Clara Bloomfield. [118]Keely and His Discoveries. (Reprint
      ed with foreword by Leslie Shepard, University Books, 1972?.
      Original edition, 1893(?).) Mrs. Moore was one of Keely's most
      faithful supporters. Keely's explanations of his theories were
      incomprehensible even to those sympathetic to his work, and this
      book provides many examples of this.
  13. Ord-Hume, Arthur W. J. G. Perpetual Motion. St Martins Press, 1978.
      Ord-Hume was an engineer who wrote extensively on antique clocks
      and other mechanisms. But his cavalier "refutations" of many of the
      perpetual motion machines are trivial and misleading. Some parts,
      particularly chapter 6, are difficult to follow. But, the book has
      the virtue of still being in print, in paperback, and as a
      historical survey of the subject it is well worth owning. However,
      the drawings in the Barnes and Noble reprint edition are poorly
      reproduced. Several internet sources have it as a free e-book, but
      require free registration to read or dowload it.
  14. Phin, John. [119]The Seven Follies of Science. D. Van Nostrand,
      1906. The line drawings are very clearly reproduced, apparently
      redrawn from original sources. The explanations often miss the
      mark.
  15. Scientific American, 1884, has references to J. W. Keely, generally
      derogatory and even sarcastic. March 19, p. 196. April 5, p. 213.
      Oct 11, p. 230. These are free online.
  16. The [120]Scientific American Supplement has seven lengthy articles
      about perpetual motion machines, described in detail, with nice
      engravings, and wry sarcasm as well. This is a free download from
      Google.
  17. Verance, Percy (Pseudonym!). [121]Perpetual Motion. 20th Century
      Enlightenment Specialty Co., 1916. This is material from Dircks'
      books, reworked and condensed "for the general reader", and has
      many of the original illustrations. It is apparently a Rosicrucian
      publication, part of a series called: History, Explanation and
      Prophecy Illustrated. Warning: The clever pseudonym has been
      appropriated by several people recently, who have no connection
      with the anonymous author of this book.

  A readable account of the Bessler story is found in:
    * Gould, Rupert. Oddities, A Book of Unexplained Facts. 1928, 1944,
      1964, University Books 1965. Chapter V, Orffyreus' Wheel.

  Some textbooks mention perpetual motion machines, or pose problems
  about them.

   1. Gettys, W. Edward, Keller and Skove. Classical and Modern Physics,
      McGraw-Hill, 1989. End of chapter problems about the Escher
      "Waterfall" (p. 347), buoyant force paradox (p. 348), and the
      weighted piston device (p. 348).
   2. Hudson, Alvin and Rex Nelson. University Physics, Harcourt Brace
      Jovanovich, Inc. 1982. Section 21.7 discusses perpetual motion
      devices, with pictures of an overbalanced wheel, a buoyancy motor,
      the 1618 closed-cycle mill, the ammonia engine, and a picture of
      the Escher waterfall, all on p. 511.
   3. O'Hanian, Hans C. Physics, W. W. Norton, 1985. Short description of
      the two kinds of perpetual motion machines, with a drawing of the
      articulated-hammer overbalanced wheel (p. 508).
    __________________________________________________________________

                                                           [lhupedu1.gif]

  Input and suggestions are welcome at the email address shown here. When
  responding to anything on these web pages please indicate the specific
  document by subject, name or filename.

  All material in this museum is © 2002, 2003 by Donald E. Simanek, with
  the exception of text and materials indicated as from other sources.
  Latest revision, Jan 2016.

  Return to [122]front page.
  Return to [123]Bob Schadewald's corner.
  Return to the [124]top of this document.

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