Inventions and Deceptions – Hammer and Feather Experiment

Commander David Scott performed the “hammer and feather experiment” on the Moon during the Apollo 15 mission in 1971.

Commander David Scott on the Moon 1971

The objective of the “hammer and feather experiment” is to demonstrate “that all objects in a given gravity field fall at the same rate, regardless of mass (in the absence of aerodynamic drag).”

After returning to the LM’s location, Scott performed an experiment in view of the TV camera, using a feather and hammer to demonstrate Galileo’s theory that all objects in a given gravity field fall at the same rate, regardless of mass (in the absence of aerodynamic drag).
He dropped the hammer and feather at the same time; because of the negligible lunar atmosphere, there was no drag on the feather, which hit the ground at the same time as the hammer.

apollo15 frame by frame
The hammer and feather falling together “frame by frame” on the Moon

Mission Controller Joe Allen described the demonstration in the “Apollo 15 Preliminary Science Report”:

A heavy object (a 1.32-kg aluminum geological hammer) and a light object (a 0.03-kg falcon feather) were released simultaneously from approximately the same height (approximately 1.6 m) and were allowed to fall to the surface. Within the accuracy of the simultaneous release, the objects were observed to undergo the same acceleration and strike the lunar surface simultaneously, which was a result predicted by well-established theory, but a result nonetheless reassuring considering both the number of viewers that witnessed the experiment and the fact that the homeward journey was based critically on the validity of the particular theory being tested.
Joe Allen, NASA SP-289, Apollo 15 Preliminary Science Report,
Summary of Scientific Results, p. 2-11

On the Earth it requires specialist equipment to accurately replicate the lunar “hammer and feather” experiment in a laboratory because of our thick atmosphere and rapid gravitational acceleration of 9.81 m/s2 – 32.2 ft/s2.

Feather in Vacuum - Backstage Science Feather in Vacuum – Backstage Science

The principles demonstrated by this experiment were very important to Commander David Scott because his “homeward journey [from the Moon] was based critically on the validity of the particular theory being tested”.

Therefore, in the interests of science, let’s simulate the “return journey” of Apollo 15 to Earth through low gravity space so that we can experimentally test the hypothesis that “all objects in a given gravity field fall at the same rate”.

Luckily, the Apollo 15 “return journey” experiment can be easily performed in your kitchen for an investment of less than two Euros. In fact, this budget is sufficient to simulate two simultaneous Apollo 15 “return journeys” in the experiment.

The first step in our experiment is the construction of two identical Apollo “command modules”.


The two “command modules” are constructed using:

1) Needlework thimbles for the main body of the “module”.
2) Sand and Rice for the two separate “payloads” placed inside each “module”.
3) Sticky-back pads as “heat shields” which secure the “payloads” into the “modules”.

Command Module Components

The completed “command modules” ready for their return journey through space.
The volume, size and shape of the “command modules” are virtually identical.
However, their “payload” masses are different [sand versus rice] and, therefore, the density of the “command modules” are different.

Two Command Modules

The second step in our experiment is to simulate a “low gravity space environment” for the return journey of our “command modules” towards Earth.

The “low gravity” space environment is created simply by filling a glass jug with water. The viscosity of the water resists the downward pull of gravity [equally] for our two identical “command modules” while the mass of water displaced by the identical “command modules” provides buoyancy [equally] which also helps to simulate a low gravity space environment.

Although this low gravity space simulation is not perfect it should be sufficient to experimentally test the hypothesis that “all objects in a given gravity field fall at the same rate”.

Placing the jug of water above a globe is pure “window dressing” to aid visualisation.

Low Gravity Space Simulation

The experiment is now performed by simply submerging the “command modules” before releasing them simultaneously on their “return journey” to Earth.


Observing the “command modules” travelling through the simulated “low gravity environment” clearly demonstrates that the “command module” containing the heavier sand “payload” accelerates more rapidly than the “command module” containing the lighter rice “payload”.

Therefore, the experiment indicates that the hypothesis [that “all objects in a given gravity field fall at the same rate”] has been falsified. Ideally, the experiment should be repeated with more precision under laboratory conditions. However, given the scale of the discrepancy observed in this kitchen experiment it seems very unlikely that a different result will be observed.

This experiment is not totally conclusive but it very strongly suggests that the mainstream hypothesis is false. The mainstream experiments which focus upon the “hammer and feather” introduce totally unnecessary complications into the process.

The experiment does not have to be performed on the Moon.
The experiment does not have to be performed in a vacuum chamber.

The experiment should [simply] be performed using identically shaped objects [with equal aerodynamic drag] of different densities.

Perhaps the most pertinent conclusion [for terrestrial based life forms] is that the “hammer and feather” experiment performed on the Moon [and in vacuum chambers] are [at best] an intellectual distraction [misdirection] in the real world [on Earth] where “nature abhors a vacuum”. When it comes to interplanetary space I have to choose between the integrity of mainstream science and the experimental results observed by my own “lying” eyes.

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20 Responses to Inventions and Deceptions – Hammer and Feather Experiment

  1. I like it. Well done. I came here looking for the theory of gravity really being a vortex and got an extra confirmation of my own theory that it is merely different densities that affected by gravity.

    Good work.

  2. The Guy says:

    The experiment is wrong. Flotability, which is not proportional to mass like gravity, distorted the results. I encourage you to repeat the experiment in real vacuum, where gravity is the only acting force.

  3. w.w.wygart says:

    Sorry, I’m with Guy, all you have succeeded in doing with your experiment is substituting a larger hydrodynamic force for an aerodynamic force, you’ve added layers of complexity rather than simplifying the situation In hydrodynamics scale factors matter, and forces do not necessarily scale proportionally In this case because of the low Reynolds numbers involved with your ‘capsules’ viscous drag is going to dominate, and if one of your capsules becomes tilted, you may also have to account for lift drag on that body due to non-zero angle of attack – among other problems.

    Also, objects where viscosity dominate reach terminal velocity rather quickly, which begs the question: at what point did your experiment stop measuring acceleration do to ‘whatever’ and start measuring the viscosity of the water?

    Even the buoyant force contains a term for ‘g’. The buoyancy force B acting on the capsule acting in a gravitational field [Earth] can be calculated with this equation:

    B = ∫ div σ dV = – ∫ f dV = – ρsub fg ∫ dV = – ρsubf gV

    Hard to get away from that ‘g’, remove the gravitational constant from any of these equations and your calculations will not agree with reality.

    As the NASA report you quoted above says, “the homeward journey was based critically on the validity of the particular theory being tested.” If the Hammer-Feather experiment was wrong, or faked, the astronauts would have died – period. In fact they never would have made it to the Moon, in fact the entire space programs Russian, US, and others would never have succeeded in anything because the equations that governed the design and operation of the spacecraft were critically dependent on Newton’s laws being correct to a very high degree of precision.

    In fifth grade science class we all rolled little balls down ramps to obtain the acceleration due to gravity and an approximation for ‘g’. A couple of years later in introductory physics we repeated the experiment and calculated a coefficient of friction and obtained an even better value for ‘g’. These experiments worked well. If you are really interested in falsifying Newtonian gravity you will have to find a term for your Rankine vortex theory that functions identically to ‘g’ in all of the equations were it has worked almost flawlessly for the last three hundred years – at least at scales smaller than galaxies.

    If you faithfully replicate the Hammer-Feather experiment by traveling yourself to the Moon, or by obtaining use of a vacuum chamber you will discover that Newton is correct – at least at limited scales of distance. The scientific method doesn’t proceed entirely by one ‘confounding’ experiment, you could be in error, you also have to demonstrate why the previous understanding is wrong by showing the errors in their experiments. Now go and try and replicate the other experiments – faithfully – and show how they fail.

    As for the Galaxy Rotation Problem, maybe we can find some agreement at your other page.



    • malagabay says:

      The buoyancy is determined by the displacement… that is why I used two identical “capsules” so that the buoyancy and the drag would be equal.

      The key to doing the experiment intelligently is to isolate the gravitational force by making all the other “forces” equal… like equal buoyancy… and equal drag so the air [or water] resistance is equal.

      In a high viscosity environment [like my experiment in water] the “density effect” shows up very quickly… in a low viscosity environment [like air or a vacuum] the “density effect” develops over a greater distance.

      The bottom line [for me] is that the experiment should always be performed:
      1) using identically shaped objects [of the same size] that are of different mass.
      2) over a distance appropriate for the density environment.

      None of the other “hammer and feather” experiments I have seen performed meet those two basic requirements… until such time as I see valid experiments performed [that meet those two requirements] I am sticking with my own experimental results…

      However, you are free to form your own opinion on the matter…

      • w.w.wygart says:

        Remembering my main point, that Guy also pointed out, your experiment does not simulate the a vacuum environment the way you hope. That said, once your capsules, nearly identical except for mass, reach terminal velocity and one or the other starts to tumble, as evidenced by your photo, all bets are off – and that’s just classical hydrodynamics.

        Remember, the original Apollo capsules reentered earths atmosphere at a slight angle which was designed to generate lift and thus a steering moment during reentry.

        My challenge to you remains, attempt to replicate your experiment with your two capsules in a vacuum, or on the moon FIRST and show that it does not work, THEN show why with your improved experiment. Attempting to reason from the ideal environment, a vacuum, to a simulated environment doesn’t work in my book. And, you still haven’t shown hot the Apollo astronauts could have survived the trip with such a faulty understanding of physics.

        And, and, I also really what to see what term you propose to replace the Gravitational Constant with that work identically well in ALL the classical equations – at least up to the galactic scale.

        I actually share your skepticism of Dark This, and Dark That, smells like an ad hoc hypothesis to me. We’ll see if any of these brainiacs at LUX, ‘ore’ elsewhere are actually able to interact with one of their pet WIMPS, we’ll see, I’m not expecting to live to see the day. I may have more to say on your other page or my own blog.


      • Peter Donis says:

        > The buoyancy is determined by the displacement

        No, it isn’t. It is determined by the difference between the weight of the object, and the weight of the water the object displaces. So two objects with the same displacement, but different weights, will have different buoyancy. That is why the two objects in your experiment fall at different rates. Your experiment is not a valid test of how gravity works in vacuum.

  4. Stephen Kovaka says:

    I’ve got to vote against the validity of the experiment. You could equally well have used two identical capsules, one filled with lead shot, the other with only air. Air does have some mass, but obviously, the capsule filled with air will not sink at all, The problem is buoyancy in the medium, i.e. mass of the loaded capsule vs. mass of the medium displaced by the loaded capsule. Objects dropped in essentially airless space displace negligible mass, hence the buoyancy factor is eliminated. Objects dropped in air will also be subject to a buoyancy effect, but of so small a magnitude that it would be hard to measure and could usually be ignored.

  5. Stephen Kovaka says:

    Sorry to be dense, but I am having trouble seeing what you are driving at. Yes, observation shows that gravity results in density separation. Therefore . . . what?

    • malagabay says:

      Gravity is all about density not [Newtonian] mass is the point I am trying to convey… some get it… other don’t. No problem.

      Don’t worry – most people think I’m a fruitcake] for challenging the Settled Science of Newton…

      • George says:

        Yeah, I don’t get it, I must admit.

        I also think I struggle with the stated aim of making things mechanical with “no action at a distance” and the vortex thing. Is the idea, loosely, that there is effectively an “aether” that’s pushing everything together, and that rotational motion pushes against this, leading to balanced states of movement in the various configurations we see? Something like that?

        So, we keep inertial mass (F=ma) but throw away gravitational mass, so the attempt is to return to a straightforward, intuitive “billiard ball mechanics” approach to describing things?

      • malagabay says:

        There is no “grand” aim… just ideas and observations…
        Most people “don’t get it”… that’s fine… there is no obligation…
        Simply put:
        If you are interested in the Scientific Method then I hope you find something interesting.
        If you find a posting interesting or entertaining then read on.
        If you are looking for “the answer to the universe and everything” then you are in the wrong place.
        Nothing is ever proved – only falsified.

      • George says:

        Nothing is ever proved – only falsified.

        Indeed! Anyway, all very thought-provoking – thanks. (Personally, I always liked the idea of an aether, as opposed to “fields without a medium”, and removing the “inertial mass = gravitational mass” fudge if possible would be a great step.)

  6. Jeff says:

    Gravity only seems to separate densities when there is a buoyant force at work, and that ends up relating to both inertial mass and gravitational mass. Also, there is nothing wrong with questioning Newton; my physics teachers do it all the time and encourage us to do the same. I think the problem here is the manufactured “us vs. them” attitude where you conveniently place yourself in the “victim’s” position with all the baddie, dogmatic Newtonians against you.

    In the end Newton not only could be wrong, but he _was_ wrong, which has been proven by observation. He came up with a model that explains what we observe in a predictable fashion, so we still use his models. It’s no biggie. When his equations stop being useful, we’ll stop using them. Even if they are flat out _wrong_ (and they are, btw), we can still use them for the sake of usefulness and convenience.

    Perhaps your model can explain and make predictions as well. If so, great. But, if your model isn’t as simple as Newton’s, it won’t be adopted because humans like simplicity and tradition. There is no conspiracy making you out to be a “fruitcake,” it’s just that Newton’s model is easier to use and still explains everything in our practical experience. Taking your argument farther I could argue that there is no such thing as gravity, density, vacuum, or mass. Those are all just human models, and humans don’t dictate how nature works; we just build models, fill the internets, and generally muck about.

  7. Jeff says:

    Also, I forgot to mention that your argument is an equivocation fallacy. The “homeward journey” was in regards to leaving the Moon using an ideal amount of fuel and calculating orbit transfers from the Moon to the Earth. All of which has nothing to do with density or buoyancy. They weren’t talking about atmospheric travel.

    I think your experiment is cool though, and it makes me want to build little capsules to see how they react to various forces…


  8. Jim Coyle says:

    I don’t believe you can do you r experiments in the vacumm of space or the moon because there is still gravitation force(s) at play. All bodies over a certain size ( i’m not sure of the mass) have gravity, the bigger the body the bigger the gravity. Out in space there is all kinds of garvity pulling at your capsules so your experiment cannot possibly produce results. Also in the absence of gravity when your capsules are released they will not fall unless there is some kind of force applied. I’m of the opinion that gravity is some kind of vortex but I’m not sure how a globe can produce a vortex.

  9. Apart from the nonsense of a point having mass. Points are locations in a geometrical field, have no volume and hence cannot contain matter and thus possess mass. Spot on Tim.

  10. Engineer says:

    The Resistance Force of moving through the water/fluid/air is proportional to the second of the velocity (F proportional velocity * velocity). The higher density part has a higher resultant force (Gravitational Force minus buoyant force), and finds its force equilibrium (where there is no more acceleration) at a higher speed, and of course accelerates faster until that point.

    Despite the rest of the site being quite interesting, here is a basic lack of understanding of technical mechanics. An engineering book on technical mechanics should bring some clarity.

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