Simple rotational pendulum to verify how light blocks gravity.

Simple rotational pendulum to verify how light blocks gravity.

note: The online version is free access and download.
Applied Physics Research Vol.  7,  No.  4,  August 2015  issue.
under Further Experiments Demonstrating the Effect of Light on Gravitation
Louis Rancourt, Philip J. Tattersall 

1. Use a cardboard box at least 1.2 m by 1 m by 1 m.

2. Use a meter stick to hold 2 cylindrical lab masses, one at each end. ( they can be replaced by 2 similar objects)

3. Suspend the meter stick at mid point by 3 fine copper wires ( take them from an old extension cord)

N.B. The attaching point on the screw at the center of the stick has to be higher than the mid point of the masses; otherwise, it is impossible to balance the stick. )Capture 30

4. Use a support for attaching the upper wires as on the figure.

5. Put a pointed cardboard under the front end of the ruler; place a ruler under without touching the pointer.

6. Place a glass plate in front of the box. ( do not use plastic because it makes static electricity easily and that will influence the results.

7. Before closing the box, put water vapour in the box; the vapour will eliminate any static charges.

8. Outside the box, use a smaller box to hide a lamp. Make sure it will not catch fire.

9. Let the pendulum rotate back and forth for one day. You can then light the lamp and watch the swinging movement slowly bring the mass towards the hidden lamp.

10. Close the current in the lamp and the mobile mass will return to its normal position.

N.B. If it is well constructed, the pendulum should be always moving a fraction of a degree because of earth motion.


Explanation: Gravity is a force going in all directions, vertically, horizontally and all angles. When light is activated, it blocks some of the force going horizontally towards the mass; the force coming from the other side is now bigger and it pushes the mass towards the lamp.

N.B. The box containing the lamp could be made of steel and the effect will be still visible; that demonstrates it is not air movement or heat that causes the motion because the motion starts when the lamp is activated and there is no time to heat inside the big box.

pendule 1

Inside the cardboard box, with support and torsion pendulum

pendule 2

Mass and pointer details

pendule 3

ruler under the pointer to see the movement

pendule 4

Lamp outside the box;


pendule 5

Complete setup.

About Louis

In this site, I will give a summary of the discoveries to date and the new one also. My family helps me a lot: Benoît is discussing the findings; my wife Madeleine, a nurse is helping also. My daughter Rosanne devised this WEB site and her husband Jamie is a proficient programmer who can help me a lot, even with his big family of 7 nice kids. I am now retired after 52 years of teaching mostly physics and maths. Bonjour Je suis un professeur de sciences depuis plus de 50 ans. J’ai enseigné de la 7e année à la 12e puis à l’université d’Ottawa et enfin au collèege. J’enseigne depuis plus de 25 ans au collège Boréal, Sudbury, Ontario, Canada. Depuis le début, je désirais comprendre la gravité. Après beaucoup d’essai infructueux, j’ai découvert qu’un rayon de lumière peut bloquer la force de gravité. Encore beaucoup de recherche permettront de comprendre la nature de la gravité. Mon grand gars Benoît ia fait un baccalauréat en Sciences infirmières . Il m’a beaucoup encouragé dans ma recherche. Mon épouse Madeleine est infirmière et ma grande fille Rosanne a réussi à faire ce site WEB malgré le travail avec ses 7 beaux enfants. Mon gendre Jamie Parent est programmeur et très habile avec les ordinateurs. Louis Joseph Rancourt
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3 Responses to Simple rotational pendulum to verify how light blocks gravity.

  1. Keith Cornett says:

    Since the force measured by this experiment is so small, why do you ignore a more direct calculation of the measured force by computation of the torsional force?

    • Louis says:

      The effect was big enough to be measured on an analytical balance.

    • Louis says:

      Sorry for being late to reply. In the submission of the first paper, such calcultions were made but i was asked to omit that part. Since I am using 200 g mass, the change is big enough to be visible on an analatical balance. Hope this clarify your point.
      See the last article on levitation vs zero gravity

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