[Oberon]

It wasn't though, if I understand Guth correctly. There are processes and the time spans and volumes are small but never zero.

Really?

Being a smart-aleck, the next question I'm likely to ask is "What happened before that?"

[BikerNYC]

Being a smart-aleck, the next question I'm likely to ask is "What happened before that?"

That assumes that a "before" can exist. When time periods get small enough, the very nature of before and after make no sense because on uncertainty principles.

[longshadow]

Being a smart-aleck, the next question I'm likely to ask is "What happened before that?"

BB Cosmology involves the idea that space AND time come into existence concurrently at t=0. Therefore, by definition, there is no such thing as t<0. Hence, there is no "before" the BB, as the word "before" presupposes the ability to establish temporal order, and if there is no "time" then there can be no temporal order.

The standard way of illustrating this is to use the analogy that asking what is "before" the BB is like asking what is North of the North pole, or what is colder than absolute zero.