Mechanics and Astronomy¶
Core Argument¶
This chapter fragment advances a dialectical materialist critique of classical mechanics and astronomy, exposing the metaphysical limitations embedded in Newtonian physics and their ideological consequences. The central argument is that Newton's laws, while empirically useful within certain bounds, become positively erroneous when treated as absolute truths rather than approximations valid only under specific conditions.
The law of falling bodies serves as the opening exhibit: Galileo's law assumes the Earth's radius is effectively infinite, but for falls lasting several minutes this assumption breaks down because gravitational attraction increases rather than remaining constant. Yet the law continues to be taught without this crucial reservation—a concrete demonstration of how metaphysical thinking ossifies scientific knowledge.
Newtonian gravitation receives the most sustained polemical treatment. Engels argues that Newton's parallelogram of forces does not solve the problem of planetary motion but merely restates it, transforming a description into a pretended explanation. By postulating a tangential force alongside gravitational attraction, Newton creates a theoretical necessity for a "first impulse"—God—because the model presupposes the eternal character of existing planetary states. The dialectical alternative recognises that planetary motion was originally simple rotation, not compound, and that the parallelogram of forces only holds momentarily when annular bodies separate from a rotating mass. Once separation is complete, motion becomes a unity again; the very fact of separation proves dialectical process at work.
The chapter then surveys contemporary astronomical work, particularly Mädler's studies of fixed stars and the Milky Way. Mädler's calculations are dismissed as "as crazy as anything in Hegel's Philosophy of Nature"—a striking comparison that suggests even Hegel's speculative excesses have empirical counterparts. The Pleiades group, with Alcyone as its putative centre, yields a calculated mass of 118 million suns within a radius of 573 light years, yet contains at most 2 million visible stars. This discrepancy points to dark bodies or, more fundamentally, to the inadequacy of observational bases.
A notable argument against Olbers' paradox appears: the darkness of the night sky requires no special explanation via light absorption, since light's finite velocity combined with the finite time since creation means we can only perceive objects within a certain distance. This implicitly invokes a temporal, historical universe rather than an infinite static one.
The discussion of nebulae reveals a universe in process. Some nebulae are resolvable into stars; others, like those in Orion and Lyra, show spectral lines of nitrogen and hydrogen, proving they are "true nebulae"—glowing gaseous substances, not star aggregates. This spectral evidence demonstrates matter in transition between states, supporting a dialectical view of cosmic development.
Secchi's concluding question—whether dead systems can be reconverted to glowing nebulae and reawakened—receives no answer from established science. The chapter implies that dialectical materialism, by recognising the cyclical transformation of matter through contradiction, can provide what mechanical materialism cannot: a coherent account of cosmic renewal.