Francesco Maria Grimaldi

Between 1640 and 1650, working with Riccioli, he investigated the free fall of objects, confirming that the distance of fall was proportional to the square of the time taken. Grimaldi and Riccioli also made a calculation of gravity at the Earth's surface by recording the oscillations of an accurate pendulum.J.L. Heilbron, Electricity in the 17th and 18th Centuries: A Study of Early Modern Physics (Berkeley: University of California Press, 1979), 180.

In astronomy, he built and used instruments to measure lunar mountains as well as the height of clouds, and drew an accurate map or, selenograph, which was published by Riccioli and now adorns the entrance to the National Air and Space Museum in Washington D.C.

He discovered and was the first to make accurate observations on the diffraction of lightFrancesco Maria Grimaldi, [https://books.google.com/books?id=FzYVAAAAQAAJ&pg=PA1 Physico mathesis de lumine, coloribus, et iride, aliisque annexis libri duo] (Bologna ("Bonomia"), Italy: Vittorio Bonati, 1665), pp. 1–11 (in Latin).{{cite book|author=Florian Cajori|title=A history of physics in its elementary branches: including the evolution of physical laboratories|url=https://books.google.com/books?id=KZ4C-1CRtYQC&pg=PA88|access-date=14 August 2011|date=1899|publisher=The Macmillan Company|pages=88–}} and coined the word 'diffraction'. In his book Physico-Mathesis de Lumine, Coloribus et Iride (1665), he stated the theory of the reconstitution of sunlight from refracted coloured light.{{cite book|author=David L. MacAdam|title=Selected Papers on Colorimetry - Fundamentals|date=1993|publisher=SPIE, The International Society for Optical Engineering|isbn=0-8194-1296-1|pages=xiv-xvi}} (There is a far-fetched account that Leonardo da Vinci had earlier noted the effectGuglielmo Libri, [http://www.mmi.unimaas.nl/people/Veltman/books/contin/title.html Histoire des sciences mathematiques en Italie] {{webarchive|url=https://web.archive.org/web/20061128134717/http://www.mmi.unimaas.nl/people/Veltman/books/contin/title.html|date=2006-11-28}} (1840){{Cite book |last=Libri |first=Guglielmo |url=https://archive.org/details/UFI0301854_TO0324_84659_000003/page/244/mode/2up?view=theater |title=Histoire des sciences mathematiques en Italie, depuis la renaissance des lettres jusqu'a la fin du 17. siecle / par Guillaume Libri Vol. 3 |date=1840 |publisher=A Paris : chez Jules Renouard et C.ie, 1840}}.)

Through experimentation he was able to demonstrate that the observed passage of light could not be reconciled with the idea that it moved in a rectilinear path. Rather, the light that passed through the hole took on the shape of a cone. Later physicists used his work as evidence that light was a wave, significantly, Dutch mathematician Christiaan Huygens. He also discovered what are known as diffraction bands.{{cite book|author=Thomas E. Woods|title=How the Catholic Church built Western civilization|url=https://books.google.com/books?id=zVDR2ZePzvUC&pg=PA105|access-date=14 August 2011|date=2005|publisher=Regnery Publishing|isbn=978-0-89526-038-3|pages=105–}}

The crater Grimaldi on the Moon is named after him.

He only published one work:

• {{Cite book|title=Physico-mathesis de lumine, coloribus et iride aliisque adnexis|volume=|publisher=Johann Zieger|location=Girolamo Bernia|year=1665|language=la|url=https://gutenberg.beic.it/webclient/DeliveryManager?pid=871571}}

The work is mainly remembered for being the first report of diffraction. In the work, he was mainly concerned with two questions:

1. Is light a substance or an accident [roughly the same as "property"]?
2. What is the relation between light and color?

He argued that light is probably a subtle fluid (thus a substance), though it might still be an accident (as Aristotelians believed). He also argued that color is associated with undulations of the subtle fluid.{{Cite journal |last=Lindberg |first=David C. |date=April 1969 |title=Physico-mathesis de lumine, coloribus, et iride . Francesco Maria Grimaldi |url=https://www.journals.uchicago.edu/doi/10.1086/350461 |journal=Isis |language=en |volume=60 |issue=1 |pages=119 |doi=10.1086/350461 |issn=0021-1753}}

• List of Jesuit scientists
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• {{Catholic|wstitle=Francesco Maria Grimaldi}}
• Grimaldi's (1665) [http://lhldigital.lindahall.org/cdm/ref/collection/color/id/6930 Physico-mathesis de lumine] {{Webarchive|url=https://web.archive.org/web/20170808153150/http://lhldigital.lindahall.org/cdm/ref/collection/color/id/6930 |date=2017-08-08 }} - digital facsimile from the Linda Hall Library

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Category:1618 births

Category:1663 deaths

Category:17th-century Italian Jesuits

Category:17th-century Italian mathematicians

Category:17th-century Italian physicists

Category:Selenographers

Category:Jesuit scientists