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Hardware Science

Scientists Build Smallest, Single Atom, Working Heat Engine (popularmechanics.com) 53

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.
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Scientists Build Smallest, Single Atom, Working Heat Engine

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  • Smallest? (Score:5, Insightful)

    by Anonymous Coward on Friday April 15, 2016 @02:07PM (#51916539)

    I think the part that creates nano-sized cone of electromagnetic radiation counts as part of the engine.

    • Sometimes anonymous first post is the best post. One atom is a ridiculous claim.

    • Re: (Score:3, Insightful)

      by Thelasko ( 1196535 )

      I think the part that creates nano-sized cone of electromagnetic radiation counts as part of the engine.

      I question it being called a heat engine at all. The energy source is a laser. A laser is a highly organized beam of radiation. Heat is disorganized. This seems to have more in common with a photoelectric effect. [wikipedia.org] The big difference from the photoelectric effect being the fact this system creates mechanical work instead of electric current.

    • Re:Smallest? (Score:4, Insightful)

      by somenickname ( 1270442 ) on Friday April 15, 2016 @03:53PM (#51917367)

      My initial thought as well. Reading the article, what they've actually created is a single atom piston with insanely complex machinery to drive the piston. Still pretty cool but, pretty far from a "single atom working heat engine".

      • what they've actually created is a single atom piston with insanely complex machinery to drive the piston.

        Great analogy! When you factor in all of the equipment involved, this "engine" has perhaps the worst power density in the world.

    • by MobyDisk ( 75490 )

      Exactly! I have created a 1-atom engine that produces 320 horsepower! It is a single atom, surrounded by a 3.0L N55 Turbocharged DOHC I-6.

    • The researcher acknowledges this, as quoted in the article:

      Roßnagel openly admits that you won't find his four-stroke motor in any nano-sized robots anytime soon. While the engine itself is tiny, the machinery required to create the electromagnetic cone and suspend the two heating and cooling lasers takes up most of a room. But Roßnagel says that's no surprise. The engine was never meant to be a functioning part of a future machine, but to reveal new insights into the fundamental science of heat e

  • Popular Mechanics (Score:5, Insightful)

    by 110010001000 ( 697113 ) on Friday April 15, 2016 @02:10PM (#51916571) Homepage Journal
    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.
    • Re: (Score:2, Insightful)

      by Anonymous Coward

      The authors of this paper are referring to the four thermodynamic states of an engine. The "4-stroke" of a combustion engine refers to the mechanical devices used to transition the system from one state to another. They are conceptually related, hence the analogy.

  • otto cycle (Score:4, Informative)

    by Anonymous Coward on Friday April 15, 2016 @02:13PM (#51916603)

    It follows the same four strokes; expanding then cooling, contracting then heating.

    These are the four strokes of the Otto Cycle.

    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.

    Intake-compression-power-exhaust are how a reciprocating piston achieves expand-cool-contract-heat.

    • by GuB-42 ( 2483988 )

      Intake-compression-power-exhaust are how a reciprocating piston achieves expand-cool-contract-heat.

      Is there a 1:1 relationship between the two?

      • by suutar ( 1860506 )

        power->expand, exhaust->cool, intake->contract, compression->heat seems closest to a 1:1 but I think it's not quite right. I think the link is more in the middle of each piston stage - expand is half power, half exhaust, cool is half exhaust, half intake, contract is half intake, half compression, and heat is half compression, half power.

        I'm interested in other interpretations :)

    • Yeah, don't really know why people want to compare a combustion engine with a heat engine, and expect the compression 4-cycle suck-stroke-bang-blow to be the same as a heat engine that works on entirely different principles...

  • by Anonymous Coward

    By "four strokes" they are probably trying to explain the Carnot cycle.

  • by danbert8 ( 1024253 ) on Friday April 15, 2016 @02:26PM (#51916721)

    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...

  • by Thelasko ( 1196535 ) on Friday April 15, 2016 @02:29PM (#51916749) Journal
    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?
    • My understanding of heat is it's the kinetic energy of molecules.

      No, that would be temperature. It's defined for a given body, and yes, it's a measure of its average kinetic energy.
      Heat is thermal energy that is being transferred from one body to another, due to a difference in temperature between those two bodies. It's defined for a given process (e.g. radiation between sun and earth). It's wrong to talk about "the heat of a molecule".
      Don't worry, you're not the only one confusing heat and temperature, I'

      • by lgw ( 121541 )

        Heat exists outside of transfer. Heat is "thermal density."

        Temperature has differing, barely-related meanings as you go up and down the scale of temperatures (e.g., the temperature at the Sun's core isn't really about kinetic energy). The unifying theme is entropy, but the temperature-entropy relationship is somewhat of an emergent property, rather than being fundamental (except for "negative" temperatures, which are only about entropy).

        • Heat exists outside of transfer. Heat is "thermal density."

          [Citation needed.]
          That sounds wrong, probably because it is wrong.

          • by lgw ( 121541 )

            Unless you're being pedantic even by /. standards, "heat" is what "heat transfer" transfers. You can speak of the heat in an object (the heat that could be transferred to another object or to an environment at some reference temperature, perhaps 0) , change in heat, specific heat, energy density in terms of heat or specific heat, and so on.

            • Thermodynamics is basically statistics with huge numbers of particles : it is really important to carefully define (i.e. be pedantic about) every system, process and properties. You can get very wrong results very fast otherwise.
              So no, "heat transfer" doesn't transfer "heat", but thermal energy. Heat is just the name for thermal energy flowing from one system to another. It stops being heat as soon as it arrives.

              You can speak of the heat in an object

              You *cannot* speak of the heat in an object. It is mathe

              • by lgw ( 121541 )

                Yes, yes, insist on your technical jargon, while most of us continue using "heat" as a synonym for "thermal energy".

        • Heat exists outside of transfer.

          No it doesn't. Heat is not a well-defined thermodynamic state variable: two identical systems can have different "quantities of heat" in them. That's basically the whole idea behind a heat engine: you put thermal energy into a system, and you get out mechanical energy (and as a result you end up with less heat).

          Temperature has differing, barely-related meanings as you go up and down the scale of temperatures (e.g., the temperature at the Sun's core isn't really about kinetic energy)

          No, they're all pretty much the same definition, just applied to specific models. For e.g. an ideal gas assumes non-interacting particles, which becomes very non-true at high pressures and temperatu

          • by lgw ( 121541 )

            two identical systems can have different "quantities of heat" in them

            How would that work, then? Unless you're just saying that "heat" it only meaningful relative to some floor, just like potential energy, in which case fine.

            Temperature is precisely defined the same in all cases

            And that definition would be? Or do you mean the concept is the same, but the definition in terms of how it may be determined varies? In that case I agree. But concepts are qualitative and temperature isn't a very useful concept without some way to quantify it. Emission spectrum works well for ideal black bodies, sure, and entropy works well for most

      • Heat and kinetic energy are both energies. Factoring out material properties like mass and specific heat means temperature is more analogous to the velocity of the particles.

        The reason water absorbs heat at 100C and doesn't increase in temperature is because the kinetic energy of some of the water molecules become high enough that they escape the pot in the form of steam.
        • by DRJlaw ( 946416 )

          The reason water absorbs heat at 100C and doesn't increase in temperature is because the kinetic energy of some of the water molecules become high enough that they escape the pot in the form of steam.

          That is not what he was referring to. There's an enthalpy of vaporization [wikipedia.org] that requires that you transfer energy to the system (heat) in order to make the leap from liquid to gas at the boiling point of the liquid. That phase transition occurs at constant temperature so long as you're maintaining constant pre

          • I think you're describing the same process, but thanks for the clarification!

            • by DRJlaw ( 946416 )

              That was not my impression. There's a bulk, "mechanical" process where the temperature stays constant because water is boiled into steam which leaves the system. But there's also an underlying, physiochemical phase transition where you could (theoretically) add energy just short of the enthalpy of vaporization without generating any additional steam (remember, the saturated gas phase issue). You can't actually do that due to statistical thermodynamics, but the enthalpy of vaporization is a form of physic

  • Woot! Can't wait for the Borg nanoprobes! Resistance is futile..

  • by Sique ( 173459 ) on Friday April 15, 2016 @03:47PM (#51917319) Homepage
    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.

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