Everything Is One Non-Local Source/Self Manifesting An Infinity Of Localized Selves

Why is there such a prevailing assumption in rationalists that death is the eternal extinction of being?

Some atheists will use the example that most of us don't remember anything before we're born. But.. the lack of memory of before-birth isn't equivalent to nonexistence for eternity before life began. It's just evidence that you don't remember simply.

Think about it. We don't know that consciousness is ever not present for itself, in some manner. Yeah, we don't seem to be there in deep-sleep, coma, syncope (fainting), vegetative states or before our inception. But for the experiencer/subject/agent it may always be existent, throughout all of these supposed gaps in experiencing.

Because really, we regard the nothingness of unconsciousness as quite plausible, it seems to feel right, doesn't it. But, according to physics, namely quantum field theory, nothingness doesn't exist.

Here's a quote distilling how nothingness isn't a reality of nature:

"So around the turn of the 20th century, physicists started to discover that the actual nature of the universe isn't quite what people thought it was. Before then, people pretty much looked around them and had theories of the universe, Newton's law and Maxwell's equation, that corresponded to what we see with our senses and the way we think with our minds. But then physicists started to look deeper. When they started to look deeper, a lot of counterintuitive and hard to understand concepts came up which can be understood and described with mathematics. One of them is this concept of nothingness. According to quantum theory, there is no such thing as nothingness. You can have nothingness in quantum theory. But from that, things will arise. You'll pop into existence and out of existence again. So I know that's hard to understand and hard to accept. But that particular phenomenon has been tested and confirmed many times in the laboratory."

It comes from a theoretical physicist Leonard Mlodinow. He co-authored the book The Grand Design with Stephen Hawking. He's not just a run-of-the-mill physicist, as you can see.

What he's saying is that nonexistence is nonexistent. There never was nothing. There never will be nothing. So why, if there isn't nothing, should nothing occur at any moment during your lifetime or before birth/after death. If nothingness truly doesn't exist physically - 'out there', and we're fully physical (as science would pronounce, including consciousness itself being physical), then the actuality of nothingness taking place at any instance 'in here'/subjectively/experientially is implausible.

Just why should subjective nothingness be real, and objective nothingness of space/the vacuum be unreal?

Reconsider your notions of what may be, I'd advise. The world isn't what it seems. There's something behind the scenes - an invisible connectivity between everything ever. A tetherance, unbreakable, eternal. We're not going anywhere, we never moved an instant. We're something unmoving, the dynamic movement on the screen of awareness is an illusion playing itself out. We're co-creators of this entire physical reality we're interacting with. It's our combined imagination of what could be. Let's make it a positive one. Better than that, let's create heaven on Earth for all beings ever, respecting the Earth itself.