Chapter 1: Section 7: Page 58: Line 29 (1010)

 Lord Salisbury said it was only a noun for the verb 'to undulate.'

**********

"Lord Salisbury"
Robert Arthur Talbot Gascoyne-Cecil, 3rd Marquess of Salisbury. He was Prime Minister of the United Kingdom three times in the latter half of the 19th Century. I don't know why he was weighing in on the possible existence of Æther except that people sometimes want to know what powerful politicians think. This guy seemed pretty smart if absolutely a model of conservative British politics. My favorite bit about him was his credo: "Whatever happens will be for the worse, and therefore it is in our interest that as little should happen as possible." Being the leader of the greatest imperial country of the 19th Century, this motto did not stop him from winding up with the most territory in the Scramble for Africa. I suppose that was more a case of the worst happening and less a case of as little should happen as possible. Because, you know, Britain could have sat out plundering Africa with the other imperialists, could they have not?

This guy looks like his credo.

"a noun for the verb 'to undulate.'"
I don't know if he really said this or this is just Pynchon fictionalizing some possible dialogues surrounding Æther at the time but it definitely sounds good! The main reason for Æther's existence was to give light waves something to travel, or undulate, through. The movement of light waves simply needed a medium, or noun, to make sense.

Chapter 1: Section 7: Page 58: Line 28 (1009)

 Some don't believe in it, some do, neither will convince the other, it's all faith at the moment.

**********

Think about science as theories based on observations and we can understand the kind of "faith" Heino means. If early "scientists" (just meaning curious people who actually consider the world around them rather than horny people just trying to get laid (which we need too! I'm not judging!)) were to first observe fish, and the only thing they knew was that they, and most animals they knew of, would drown underwater, they would probably come up with a story, or theory, as to how the fish survives. Religion is theory based on observation without evidence. That's where faith actually lies. Science is theory based on the current best understanding of what's being observed and which everybody knows is liable to change with new evidence. That's hardly faith! But back to the fish watchers! A theory one of the early scientists might come up with is that fish don't need to breathe. They're just different. Everybody might nod their heads and say, "Yeah, yeah! That sounds reasonable. They seem fine underwater yet no animals we know of can breathe underwater. Therefore fish don't breathe." Belief in that story would be Heino's version of faith. It makes sense through observation and an understanding of the world around them. But as soon as somebody takes a fish out of the water and sees the way it gasps and eventually dies, the theory would immediately change. Obviously the fish is trying to breathe! But it drowns on land the way people drown underwater! So they do breathe but they seemingly breathe water. Boom. That's the new story that some will believe, some won't, and nobody will convince the other because the evidence to support either assertion isn't in yet. It's all faith.