I am confused by the requirements for straight lines connecting to the source. If the points within the opening BG are themselves the sources of circular emissions, then those circles will propagate around the edge, which is what we observe in nature.
With respect to the straight lines connecting to the source, I think that Huygens is trying to impress upon us the idea that a light wave is moving out radially from the source, without taking detours. Without this movement in straight lines, I don't think that his arguments about reflection or refraction, to be presented in the upcoming posts, would hold water.
Nevertheless, as you write, the intermediate points would have a wider reach around obstructions. But as reader @thinking-turtle noted, Huygens writes that light does spread around a corner, but the little light that does is too feeble to see.
I am not sure how much of this was known from an observational point of view in 1690, when Huygens published the Traité de Lumière.
Thanks for another thought provoking blog! Huygens writes "the parts of the partial waves which spread outside the space ACE being too feeble to produce light there." Every particle of ether becomes its own light source. If I understand it correctly, Huygens says light does spread around a corner, but the little light that does is too feeble to see.
This is fascinating, I'm becoming obsessed with waves!!
Thanks.
I am confused by the requirements for straight lines connecting to the source. If the points within the opening BG are themselves the sources of circular emissions, then those circles will propagate around the edge, which is what we observe in nature.
With respect to the straight lines connecting to the source, I think that Huygens is trying to impress upon us the idea that a light wave is moving out radially from the source, without taking detours. Without this movement in straight lines, I don't think that his arguments about reflection or refraction, to be presented in the upcoming posts, would hold water.
Nevertheless, as you write, the intermediate points would have a wider reach around obstructions. But as reader @thinking-turtle noted, Huygens writes that light does spread around a corner, but the little light that does is too feeble to see.
I am not sure how much of this was known from an observational point of view in 1690, when Huygens published the Traité de Lumière.
Thanks for another thought provoking blog! Huygens writes "the parts of the partial waves which spread outside the space ACE being too feeble to produce light there." Every particle of ether becomes its own light source. If I understand it correctly, Huygens says light does spread around a corner, but the little light that does is too feeble to see.
Yes, I think you are correct in your understanding. Thanks for reading so carefully.