Q.“Every great physical theory starts as a heresy and ends as a dogma”. Give some examples from the history of science of the validity of this incisive remark.

A radical new physical theory typically overturns some deeply held, intuitively "obvious" belief, so it is first dismissed as heresy by the scientific establishment of the time. If it survives rigorous testing, it is absorbed into the accepted framework so thoroughly that later generations treat it as self-evident "dogma," sometimes even resisting the next revolutionary idea in turn. Historical examples:

• Heliocentrism: Copernicus's Sun-centred model, and Galileo's telescopic evidence for it, were condemned as heretical by the Church in the 17th century. Today the Sun-centred solar system is taught as an obvious fact.
• Continental drift / plate tectonics: Alfred Wegener proposed in 1912 that continents drift; geologists mocked the idea for decades because no mechanism was known. By the 1960s, seafloor-spreading evidence turned it into the bedrock (pun intended) of modern geology.
• Wave–particle duality / quantum theory: The idea that light behaves as both wave and particle, and that matter has wave-like properties (de Broglie), was deeply counter-intuitive and resisted even by some of its own founders (Einstein's unease with quantum indeterminacy is well known); it is now the accepted foundation of atomic and particle physics.
• Germ theory of disease: Pasteur's and Semmelweis's claim that invisible microorganisms cause disease was ridiculed by contemporary doctors (Semmelweis was institutionalised for insisting doctors wash their hands); it is now unquestioned medical fact.

In each case, the same community that resisted the theory later defended it as unshakeable truth — illustrating exactly the arc the aphorism describes.

Pick 2–4 well-documented historical episodes where a theory was initially rejected and later became mainstream orthodoxy. For each, briefly state (i) why it was seen as heretical at the time, and (ii) how/when it became accepted dogma.

• Giving only the 'accepted today' half of an example without showing it was once rejected (the whole point is the contrast).
• Citing an example that was never actually resisted by the scientific community (confusing public/religious resistance with scientific resistance, though both can count if made explicit).
• Listing examples with no explanation of the shift from heresy to dogma.