perpetual motion using ratchets achieved

[Joel Wright]

Well sort of>CHICAGO – U.S. patent 6,362,718 was granted on March 26, 2002. In the “field of invention” section, the patent states that it is “capable of producing electrical power without an external application of input power.” I want one.

Think of what you could do with it. You could compete with utility companies, recharge the batteries in your electric shaver without ever having to plug it in and sell electricity to your neighbors. The possibilities are endless. Sadly, it won’t work in spite of its exalted patent status.

It’s just another perpetual motion machine, which we all know violates the second law of thermodynamics and is also prohibited by statute. One thing about laws of physics is that no leader or legislature can vote a law of physics up or down. You needn’t train peace officers on enforcing these laws. They simply can’t be broken. Maybe.

In 1827, English botanist Robert Brown noticed that pollen grains suspended in water jiggled about under the lens of the microscope. Others noticing the same phenomenon named it “Brownian motion” in honor of its discoverer.



The phenomenon remained unexplained until Albert Einstein in 1905 decided to take a shot at a solution, which contributed to his receipt of the Nobel Prize for physics in 1926. What Einstein suggested was that the motion was due to the invisible water molecules hitting the visible particles and moving them a bit.

Since the particles are hit continuously from all sides, they move in a random fashion. For a long time, life was good with this explanation – that is, until Richard Feynman got his hands on the problem. Feynman suggested that we could build a device that took advantage of Brownian motion.



He suggested that we could build a tiny device that consists of a vane (on the right) and a ratcheted wheel (on the left) that is attached by an axel from which we could suspend something (perhaps a flea). Due to the bombardment of gas molecules on the vane, the vane oscillates and jiggles.

Since the wheel at the other end of the axle only turns one way because of the ratchet, motion in one direction will cause the axle to turn while motion in the other direction will not. Therefore, the wheel will turn slowly and may even be able to lift some weight (a millionth of the weight of a flea).

Though the system has no loss of energy, it performs work. This is a violation of the second law of thermodynamics for which no patent exists. Feynman pointed out that since this is a violation of the second law, it simply couldn’t work.

Unfortunately, several successful attempts have been made to actually make a Brownian ratchet. They’ve worked. The key question is: Do we now have the basis to create a perpetual motion machine? Have we found the key to free energy for all time – the ultimate free lunch?

Well, no. There is a ratchet, remember? At the scale where this happens, the ratchet too is getting bumped around as much as the vane. Every time the ratchet slams down, it dumps the free lunch back into the gas. Net result? No perpetual motion and no free lunch.

On the other hand, Brownian motors exist and work, although they do consume energy as they go. Though this would seem to be the end of the tale at this point, it’s not.

It turns out that if you start looking at the mechanisms by which DNA makes copies of itself or the way proteins are folded as they are created, there is pretty convincing data to suggest that nature has engineered Brownian ratchets to assist in these fundamental biological processes. While a Brownian ratchet is not the means to a free energy lunch, it may be core to the creation of all the foods that go into your lunch.

Next week, we’ll take a look at the international aspects of nanotechnology and why it is that Merchandise Mart may be the focal point of this future economy.



--------------------------------------------------------------------------------

Glenn Fishbine has 30 years of business and technology experience. He can be e-mailed at glenn@venture-technologies-llc.com.
Click here for Fishbine’s full biography.


Copyright 2003 Glenn Fishbine
Previous Columns:
Draper Fisher Jurvetson Bets $12 Million on 3-D Microscope (4/14/2003)
Northwestern University Melding Nanotech With Transportation (4/7/2003)
Microscopic Remains of Dead Greek Scattered Throughout Midwest (3/31/2003)
Me, You Could Become Grey Goo (3/24/2003)
Chicago's Nanosphere Isn't Actually a Nanotech Company (3/17/2003)
Herd Mentality Propelling Nanotechnology (3/10/2003)
Computers the Size of a Single Plant Cell? (3/4/2003)
Will Nanotech Evolve Death Into a Choice? (2/24/2003)
Intel Bracing For Quashing of Moore's Law (2/17/2003)
The Atomic Shopping Cart (2/10/2003)
A New Craze? Nanotech is Actually 6,000 Years Old (2/3/2003)
Something Big is Afoot in Nanotech (1/27/2003)

[ovyyus]

...Though the system has no loss of energy, it performs work. This is a violation of the second law of thermodynamics for which no patent exists. Feynman pointed out that since this is a violation of the second law, it simply couldnÂ’t work...

If energy could be successfully extracted from the thermal jiggle of gas molecules wouldn't the result be a net temperature decrease in the gas? IE: output at the rachet is proportional to gas temperature decrease at the vane :)

[ken_behrendt]

I remember having a gadget when I was a kid that was called a "radiometer". It had been invented in the 19th century and consists of an glass bulb which has been evaculated until there is only a few percent of normal air pressure left in it. There is also a pivot mounted spinner inside the bulb that has 4 thin square panels or vanes attached to it. Each of these panels is black on one side and silver on the other side.

When one places his radiometer in the sunlight, a curious effect is seen. The pivot mounted spinner will begin spinning at high speed in the direction that the silver side of its panels face. The explanation was that the black sides of the panels absorb the Sun's radiant energy and then begin emitting infrared radiation. Some of the air molecules near the surface of black sides of the panels absorb this emitted infrared radiation and their kinetic energy is increased. And some of these accelerated air molecules then impact the black sides of the panels to make the spinner turn toward the side the silver faces of the panels face. Thus, the air on the black sides of the panels is warmer and exerts more pressure on the panels there then the air on the silver sides of the panels does there.

It's a rather interesting demonstration of how radiant energy can be directly converted into mechanical energy. In accordance with the laws of thermodynamics, this device will slow down and stop when it is shielded from sunlight and the black sides of its panels cool down to room temperature.

Interestingly enough, there's a weird little experiment one can do with the radiometer. If one places a stopped radiometer in their refridgerator and closes the door so that it is dark in there, then, when one opens the door a few minutes later, the spinner on the radiometer will be found to be spinning rapidly in the opposite direction that it normally would! Now the spinner will be spinning toward the black sides of the panels.

I'm not going to reveal why this happens yet...can anybody else here figure this mystery out?

ken

[Trev]

HI Ken,
I have one of those on my bedroom windowsill, I always know if it is sunny before I open my eyes in the morning because I can here it spinning.
I'm off to the fridge, cant wait to see this... that's if I can find room to get it in :)

Trev.

[Ed]

Ken,

Photons bouncing off the silver side push the thing and it's in a vacuum, so there is no air to heat up.

So is this mystery real then?

-Ed

[Joel Wright]

All the radiometers that I see have a vertical axis.Does anyone know if there would be any benifit to a horizontal axis.I'm thinking gravity could give a increase in output with a horizontal axis.Perhaps by shading the bottom half of the wheel?

[ovyyus]

The radiometer won't work in a complete vacuum...

...To explain the radiometer, therefore, one must focus attention not on the faces of the vanes, but on their edges. The faster molecules from the warmer side strike the edges obliquely and impart a higher force than the colder molecules. Again these are the same thermomolecular forces that are responsible for thermal transpiration. The effect is also known as thermal creep since it causes gases to creep along a surface where there is a temperature gradient. The net movement of the vane due to the tangential forces around the edges is away from the warmer gas and towards the cooler gas with the gas passing round the edge in the opposite direction. The behaviour is just as if there were a greater force on the blackened side of the vane (which as Maxwell showed is not the case), but the explanation must be in terms of what happens not at the faces of the vanes but near their edges...

http://math.ucr.edu/home/baez/physics/G ... -mill.html

Thermal creep explains why the device operates in reverse in Kens frig.

[Ed]

If the vanes have a frictionless support and the vacuum is complete, then photons bouncing off the silver side of the vanes push the vanes, causing them to rotate. However, this force is exceedingly small.

If there is a good but incomplete vacuum, then a different effect called thermal transpiration occurs along the edges of the vanes, as described on this page. The effect looks as though the light is pushing against the black faces. The black side of the vane moves away from the light.

So it can work in complete vacuum, but not very good. I should have kept reading further. :(

-Ed

[ken_behrendt]

Well, glad to see the old radiometer inspired some interest in everybody.

Yes, it's an interesting toy from the Victorian Era and it should work even if the axis of rotation of the panels is horizontal, but one had better have a very low friction set of bearings supporting the working structures.

Here's why it spins in reverse in the fridge:

From thermodynamics we learn that a "good" absorber is a "bad" emitter and, consequently, a "bad" absorber is a "good" emitter.

In the sunlight, the black sides of the panels are the good absorber, but appear black because they are bad emitters of radiant energy. As a consequence they heat up quickly and, eventually, begin to emit some infrared radiation. The silver sides of the panels, by contrast, are bad absorbers, but good emitters so they reflect light and appear to be silver. As a consequence, they stay cooler than the black sides and the differential in infrared emission from both sides of a panel allows the black sides to emit more infrared radiation which heats the tenuous supply of air molecules up more on the black side of the panels. The resulting greater air pressure from these heated air molecules on the black panels makes the device spin in the direction the silver sides of the panels point.

In a refrigerator there is, obviously, no sunlight present and any infrared radiation emitted from the panels must come from their thermal energy as they cool off in the chilly fridge. In this situation, it is the property of the silver sides of the panels to be good emitters which causes them to radiate off more infrared than do the black sides of the panels. Now the air molecules on the silver sides of the panels are warmed more than those on the black sides and the resulting increase in air pressure on the silver sides of the panels drives the panels in the direction that the black panels point it! Of course, this process will come to a halt just as soon as the radiometer's temperature matches that of the interior of the fridge.

ken