1847年，亥姆霍兹出版了《力量的保存》（Erhaltung der Kraft）一書，闡明了能量守恆的原理，亥姆霍兹自由能即以他來命名。他也研究過電磁學，他的研究預測了麦克斯韦方程组中的電磁辐射，相關的方程式以他來命名。
除了物理，亥姆霍茲也對感知的研究作出貢獻。他發明了眼底鏡，以及以他命名的共鳴器（Helmholtz-Resonator），他兩部光學和聲學的著作，《作為樂理的生理學基礎的音調感受的研究》（Die Lehre von den Tonempfindungen als physiologische Grundlage für die Theorie der Musik）、《生理光學手冊》（Handbuch der Physiologischen Optik），對後世影響很大。
^Patton, Lydia, 2009, "Signs, Toy Models, and the A Priori: from Helmholtz to Wittgenstein," Studies in the History and Philosophy of Science, 40 (3): 281–289.
^Joseph McCabe. A Biographical Dictionary of Ancient, Medieval, and Modern Freethinkers. Haldeman-Julius Publications. 1945 [30 June 2012]. （原始内容存档于2013-03-23）. He was equally distinguished in physics and physiology and was the discoverer of the law of the conservatism of energy. Although he was the most eminent and most honored of German scientists, he was all his life an outspoken agnostic.
^Paul Hertz, Moritz Schlick, Malcolm F. Lowe, Robert Sonné Cohen, Yehúda Elkana (编). Epistemological Writings: The Paul Hertz/Moritz Schlick Centenary Edition of 1921 with Notes and Commentary by the Editors. Springer. 1977: xxv. ISBN 9789027705822. Lenin found Helmholtz to be inconsistent, at one place a materialist about human knowledge, at another place agnostic and sceptic, and at yet other place a Kantian idealist, in sum a 'shame-faced materialist'.使用|accessdate=需要含有|url= (帮助)
^"Kandel, Eric R.". "From Nerve Cells to Cognition: The Internal Representation of Space and Action". New York, NY. 2013: 370–391.|journal=被忽略 (帮助): p. 383
