Regarding Straight line spiral

[Learner]

Thanks very much Infinite and Learner!

Thanks Learner, thanks for your detailed answer. Your answer to my Q.4 reminds me the phenomenon where by light would bent under gravity (something like that).

On a side note, I have come across a previous post in this forum "https://www.bring4th.org/forums/showthread.php?tid=5005"

Maybe I am wrong, but I think the author in that post essentially wanted to convey the idea that from density 1-6 (7th or above I am not sure), all the creation was made from light. It just get more intense in terms of energy density. Also, to some extent, that post shed some light on the question I raise.

Wow, you found a gem of a thread there. Siren knows her stuff. Too bad she's no longer registered. 
In physics, the visible light is but a segment of spectrum of electromagnetic waves/radiations. Thus I believe when Ra mentioned Light, they meant all spectrum of Light/electromagnetic waves. Light has many properties unknown to us. When we are in 3D, we can only experience a limited properties of Light. As one evolve to higher Ds, they will experience Light in fuller and fuller forms, eventually merge back into Light (it seems). 
I think some of the replies to her thread were confused because they thought only something without a solid form can be called an illusion. But electromagnetic fields interacting with each other forming boundary and shapes that are impenetrable without force between dense 3D materials. A solid wall is probably not impenetrable to higher density beings. That's why to reincarnate here, wanderers have to lower their vibration to become suitable in a "dense" form. 

It's cool that you associated the light bending under gravity with the spiraling light concept. I'm sure there's some connection. I would say that it's not gravity that bends light but gravity giving us the illusion that light is being bent. :-D