Ghideon

I think your (rather long) answers essentially answers my question with "yes, the cold side of the Stirling engine will cool below ambient temperature if sufficiently insulated." Using a thermometer under the isolation on the cold side should be able to show this. Note that if the temperature probe is too large and is made of a material that transfers heat it may disturb the experiment. Recommendation: don't focus too much on ice based experiments unless you have some way to properly control the temperature of the ice. There seem to be many sources of errors which allows for different interpretations and varying outcomes. But you seem to claim that every single engineer* in the whole world the last 200 years are mistaken? *) and scientist, teachers and others...

I did not ask for a complete explanation or theory, just if you had an idea what to look for in the experiment or what to expect; it may trigger new ideas about how and where to measure. I did a quick check* Stirling engines are common among the suppliers of school material so there is at least a market for Stirling engines in education. I do not know the percentage ofd students that perform experiments but it was mandatory when I studied in a tech oriented school (a long time ago). What do you suggest the answer to be? Anyway, it is not withheld, examples from schools are easy to find on google or other search engine of your choice. Possible reasons for the numbers of hits to be limited: -information about minors and their school work may not be freely published online due to local laws. -The topic is not very interesting; I don't for instance see many releases of kids confirming Pythagoras or that their physics task found F=ma to be correct. *) Locally, may not apply globally

Thanks for the reply. some further reasoning about the experiment: Let's again assume one engine, per your initial setup. Insulation is good and we have means to measure the temperature at the cold side and the hot side. At the start the cold side temperature is same as ambient (room) temperature. What should we look for when the engine is started? Is it correct that you predict that the temperature will drop below ambient when engine is running*? Assume the heat added on the hot side is not the maximum what the engine can handle. So therefore we can increase the temperature on hot side . What result do you predict on the cold side? Will the temperature drop further on the cold, isolated side? I ask since this could be easier to measure; we may check the temperature differences and trends and maybe easier get rid of errors. (* I am aware of the implications of this ...)

A quick followup; let's assume the engines cold sides are adjacent (in contact) and that they are insulated (for instance using the materials you proposed early in the thread) so cold side is not disturbed by room temperature. What is your opinion* about the overall efficiency of the combination of two engines versus the sum of the two engines running separated from one another? Do your ideas allow for some additional gain since the two adjacent cold sides "help each other", if I understand you correctly. *) According to your ideas

If you wish to continue the discussion you may want to focus on the experiments instead. If this is still something you want to test, adding heating to the cold side may help in this scenario? I get the impression that your idea* allows for two Stirling engines to be mounted cold plate to cold plate to increase the efficiency of both the engines? *) If correct that is...

Quick note; have you been thinking about adding identical heating elements to both the hot plate and cold sink? A small element under the insulation on the cold side could add control to the temperature difference? I don't mean you should crank up the heat, just add a way to tune the temperature and observe how behaviour depends on temperature. Maybe in combination with the probes you posted above? https://www.scienceforums.net/topic/128644-is-carnot-efficiency-valid/?do=findComment&comment=1227752 (Sorry if this already discussed, I may have missed some nuances of the experimental details)

You believe the screenshot from the video describes how a drinking bird works? You may reduce your confusion by posting references to written material instead of videos. Anyway, your comment highlights some of the issues; the video contains existing things mixed with non-mainstream concepts.

Screenshot from the video @Tom Booth. It would be easier to quote text... You claim the video is based on your ideas and the video promotes devices that are impossible according to established physics.

The proposed ideas and the links provided speaks in favour of physically impossible devices usually labelled "over-unity". A possible cause, (good point @sethoflagos) : When over unity support creeps into a discussion it is interesting to know if it is due to bad faith argumentation or ignorance regarding physics. I'll postpone my pictures and attempts at a discussion about a simplified system until we know what the agenda is.

If your hypothesis is correct* one consequence is that it allows for less complicated devices to act as heat engines and it also allows for over unity devices**. Since over unity devices / perpetual motion does not exist according to established theories there is a misunderstanding somewhere. Looking at a simpler devices (compared to a complete Stirling engine) may be helpful. (I'll try to fix the missing images later) *) As far as I can understand your hypothesis by reading your comments, reading between the lines and the fact that link to over unity device support is posted. **) @sethoflagos raised a related point already; it might have been lost in all the details about the experiments

I'll try to fix that.

You can for instance neglect friction if the friction is very low compared to other forces. It does not mean friction is exactly zero. It means that the friction is low enough to allow for other forces, more important to the discussion, to dominate. But if you wish to complicate things, feel free to modify my example. It will not change the end result or principles, but likely make the discussion more complicated than necessary. Thanks; I need to update the spelchek on my computer.

Thanks; we assume the device mass to be negligible and friction is neglected. (It is an ideal setup intended to illustrate basic physical principles, not engineering)

Let's try*. An ideally isolated and closed cylinder contains a piston. Insulation is ideal / perfect; no heat can flow in or out of the cylinder or through the piston and no gas can escape the cylinder or pass by the cylinder: Heat is added (for instance through a temporary opening in the perfect insulation: Since the gas in the lower compartment, below the piston, is heated the piston is pushed up. The heat source is removed and perfect isolation is (re)applied. The system is now at rest and will remain so indefinitely since no heat can be transferred in or out or through the cylinder: Ok so far? If so we may move on to the next part. *) I see this as an opportunity to learn; I'm sure expert members will highlight any errors in my attempt.

I would rather say Tom creates some cool experiments and uses a variety of methods and equipment to observe the behaviour of sterling engines under different conditions. But when trying to explain the observed behaviour one can choose to relay on mainstream science or unscientific fringe stuff like Over Unity / Perpetual Motion. If seeking support for the second option on a forum devoted to the first option it should not be too surprising to meet some resistance. I think I grasp where the basic misunderstanding of physics is; I might try to explain if there is some interest.

This could be a suitable label for the video as it is posted in the mainstream section on a scientific forum: Thanks for confirming my suspicions regarding the presented ideas.

Sorry to hear that you feel that forum rules prevents a hypothesis to be posted. What I read between the lines is that the idea is basically a perpetuum mobile / over unity device (deliberately or by mistake) hidden in lots of engineering details.

Thanks for your reply. I do not yet have the skills required to dig into the details of the setup and the technical discussion, can you provide a simple statement of a hypothesis you are testing? The topic is "Is Carnot efficiency valid?" and maybe there is some way to state your ideas something like: "An ideal* sterling engine running from an input power X will in a perfectly isolated environment have the output power of Y". This may help separate any misunderstandings about sterling engines and physics from the technical details of the actual experimental setup. *) Of course not possible to build but maybe useful in stating an idea.

Good question. A few years back I think I think I asked the same thing: Reference: https://www.scienceforums.net/topic/122721-heat-engine-experiments-and-2nd-law-of-thermodynamics/?do=findComment&comment=1149108 What is the difference between the 2020 setup and the new one above @Tom Booth?

So how do you eliminate the errors?

Question @DanMP from a more naive/layman point of view: Assume we send a high precision clock as part of some planned mission. Also assume the clock measures time on the surface of the moon (or other celestial body) and there is a deviation compared to GR* predictions. Which one of A and B the likely cause? A: GR is incorrect/incomplete in this scenario; new physics/modified GR is needed to explain. B: The clock does not work as predicted. There are issues due to the environment (temperate, pressure, ...), the launch, transport or other engineering related issue. If A actually happened, how do you rule out B? Or convince the scientific community that A is the cause? The scientific consensus as far as I can tell is that A is not possible in the proposed scientific setup. *) Or SR

The masses A and B are incorrectly placed in picture, A and B should be above skaters instead if f above the walls? edit: x-post with @Genady; good explanation.

This may be of interest to @DanMP; testing GR in the context of solar gravity by using a Viking spacecraft that landed on Mars. https://articles.adsabs.harvard.edu/pdf/1979ApJ...234L.219R, (bold by me) (I got inspired by @studiot suggestion and looked for any existing or proposed experiments within the solar system.)

Thanks for the update! I'm vaguely familiar with the results from water vortex and gravel grinding on rock, resulting in a "Giant's kettle" (or "glacial pothole"). So intuitively I would say you are correct but I can't speculate about how strong the effect is or time scales involved to have a visible impact on a construction. (I have been curious about this topic; it was the second thread I interacted in when I joined this forum.)

What is the antiparticle of a photon in your idea? (Rhetorical question to highlight basic issues of the idea. Some particles, such as the photon, are their own antiparticle. https://en.wikipedia.org/wiki/Antiparticle)