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Scientists Build Smallest, Single Atom, Working Heat Engine (popularmechanics.com)
William Herkewitz, writing for Popular Mechanics: Physicists have just built the smallest working engine ever created. It's a heat-powered motor barely larger than the single atom it runs on. Designed and build by a team of experimental physicists led by Johannes at the University of Mainz in Germany, the single atom engine is about as efficient as your car at transforming the changing temperature into mechanical energy. While scientists have previously created several micro-engines consisting of a mere 10,000 particles, Johannes's new engine blows these out of the water by paring down the machine to a singular atom housed in a nano-sized cone of electromagnetic radiation. The project is outlined today in the journal Science. "The engine has the same working principles as the well-known [combustion] car engine," Johannes says. It follows the same four strokes; expanding then cooling, contracting then heating.There's some confusion here. The article says it's a "four-stroke" engine. But as we know, a four-stroke engine consists of an intake stroke, a compression stroke, a power stroke, and an exhaust stroke -- things that the engine in the article doesn't seem to have. The article doesn't mention how a single atom is able to mimic all the effects of a combustion engine. Update: 04/15 18:24 GMT by M :The article appears to have been updated for clarification.
I think the part that creates nano-sized cone of electromagnetic radiation counts as part of the engine.
It is a Popular Mechanics article, of course there is some confusion. Sensationalism is that they sell nowadays. It used to be a good magazine.
These are the four strokes of the Otto Cycle.
Intake-compression-power-exhaust are how a reciprocating piston achieves expand-cool-contract-heat.
cooling = intake; contracting = compression; heating = power; expanding = exhaust;
A heat engine is completely different from an internal combustion engine. The strokes described in the summary are the strokes of a mechanical internal combustion engine and not the strokes of a heat engine.
In this case Wikipedia would have been your friend.
https://en.wikipedia.org/wiki/Heat_engine
vs
https://en.wikipedia.org/wiki/Internal_combustion_engine
An internal combustion engine is a type of heat engine. Even says so in the wikipedia link you provided.
By "four strokes" they are probably trying to explain the Carnot cycle.
I wonder if you could put a turbo in the exhaust and use it to cram 2 atoms in the engine to get some more power out of it...
Yes it's an anecdote! Were you expecting original research in a Slashdot comment?
My understanding of heat is it's the kinetic energy of molecules. What makes an engine is the ability to get all of the molecules to exert their energy in the same direction to do work. I like to think of the fish in the net from Finding Nemo.
If you only have a single molecule, that basically means you have a heat engine. There must be some different definition of heat than I use. Perhaps they are demonstrating radiation heating?
One of our competitors trademarked the term "hypothesis". From now on, we will call them "boneheaded ideas".
[pedantic mode]
What GP said is H.E. is not I.C.E. What you're saying is I.C.E is subclass of H.E.
Both are correct statements.
[/pedantic mode]
Woot! Can't wait for the Borg nanoprobes! Resistance is futile..
You're messin' with my Zen Thing, man.....
Probably because the german spelling of the name of the lead scientist contains the "sz" letter, his family name apparently got omitted from the submussion. His full name is Johannes Rossnagel. (If you don't have the ß, use ss instead!).
It's a Sterling engine, with the hot and cold parts being provided by the lasers.
Delightfully simple, with (more or less) frictionless sliding in an electromagnetic field, and the mechanical part of the engine doing the expanding and contracting rather than a working gas.
Internal Combustion engines ARE NOT HEAT ENGINES!!! Heat in an IC engine is parasitic, a by-product of combustion, it's lost energy. IC engines run on the rapid pressure increase(expansion) from first compressing a combustible mix of air and fuel, then igniting it. The "PRESSURE" pushes the piston back down and is then relieved by opening the exhaust port. This is why it's possible to run a Turbo Charger. This is also why it's possible to run a piston engine without heat on compressed air.
The heat comes from many sources, but the #1 source is the by-product of rapid expansion via combustion.
SOOOOO tired of people mistakenly calling an IC engine a heat engine. A sterling engine is a better example of a heat engine, but even that doesn't run on "heat". It runs on the expanding or heated air pushing up the cylinder.
So, does the heat makes the electrons in atom to orbit faster? Oh, wait..
There seems to be a decent amount of confusion here.
First, technical definitions (yes, these have colloquial meanings. no, the physicists are not likely using colloquial meanings.):
System: a volume of interest demarcated by a boundary. Boundary usually described by conditions detailing what may pass through the boundary.
State functions: Properties of a thermodynamic state that depend only on the state and now how we arrived at the state (e.g. internal energy, enthalpy, temperature, pressure)
Path functions: Properties of a process dependent on the path taken to get from states within the process.
Heat is not energy. Heat is a mode or path by which energy crosses system boundaries. As one of the users mentioned, heat is a path function, not a state function. Heat is best described as spontaneous transfer of energy.
In contrast, work is the mode of energy transfer that is either affected by or affects macroscopic variables (originally visualized as steam pushing a piston e.g. mechanical work).
What most people mean when they say 'thermal energy' is either internal energy (U) or enthalpy (H). Both are state functions.
Working fluid: A gas or liquid that undergoes thermodynamic state changes.
Heat engine: Any device that is connected to two reservoirs of working fluid (one hot, one cold) that extracts work from heat transfer between the two reservoirs. (It is not possible to convert all heat drawn from the hot reservoir to work - 2nd law). In an ICE, the hot reservoir would be the state right after the charge undergoes combustion and the hold reservoir is the car, air etc. An ICE is a heat engine; performance is measured against the Carnot engine. (yes, heat doesn't move the piston. But by definition, heat never moves pistons. Refer to undergrad thermo text.)
So now that we are all on the same page: What exactly happened in this experiment?
They trapped a single ion in an EM field and showed that the system could still be analyzed meaningfully from a classical thermodynamics standpoint. The point of doing this, like the researcher says, is to study the intersection between classical, statistical thermodynamics and quantum mechanics. This device is largely useful for physicists that care about this sort of stuff and not most other people.
Will it power nanobots? No.
Will it power anything? Unlikely.
Is it actually as efficient as an ICE? No. Science article reports efficiencies of around 0.3%. A typical ICE is about 30% efficient. It has a similar specific energy, which is not the same thing as efficiency.
Should the lasers count as a part of the engine? Yes. The only claim that the original article makes is that the working fluid was reduced to one atom, not the entire heat engine.
Should this have made it to Popular Mechanics? No. Neither PM's demographic nor the guy who wrote the article is likely to be able to place the experiment in context.
P.S. I greatly dislike Popular Mechanics and Popular Science now.. largely because they do more to obfuscate than to educate. Whatever, hype sells.