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Comment by istjohn | Hacker News Reader

This is what gets me. I can imagine no space and no time. But in a reality without space and time, by definition, nothing happens. There is nothing to act or be acted on. There is no timeline by which to order cause and effect. But the Big Bang posits that, in fact, something did happen: space and time began. The most incredible event imaginable occurred in the most impossible circumstance. It just doesn't compute for me. It's much easier for me to imagine that time is just turtles all the way down.

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I feel it was just logic: nothing existed, but what is nothing? To define nothing you have to define what "something" is. So there should be something to allow the existence of nothing.

> The most incredible event imaginable occurred in the most impossible circumstance.

Think of time as "it prevents everything happening at once". Before there was time, nothing prevented everything happening at once, without space nothing prevented everything happening in the same place, so everything happened at once and in the same place. That everything happening made so much noise that it created space and time in a very big bang.

What is that "something" that is happening all at once? In my naive understanding of cosmological theories is they seem to end in probabilities (e.g., eternal inflation) that emerge from a kind of (oxymoronic) "chaotic static", but what does that mean for this to "happen all at once"? That statement seems to imply there's no degree of freedom through which something can occur (at least casually).

I suppose the question comes to, what is time? I imagine "time" to be a degree of freedom through which something can change. I understand some see time to be related to entropy, and that it's an emergent property of this thermodynamic property but this seems too limiting. It would seem entropy is more-so an explanation for the arrow of time, but not time itself.

If time is defined as the dimension through which something can change then should time not be fundamental to any cosmological theories that extends beyond the Big Bang?

A series of causal events requires network reccurance for time to be calculable. If it's not calculable it can't be said to exist in any mathematical sense. So, a series of non-reccurent causal events at the fundamental level processes causally without the existence of time.

The same is true of "space" for the same reason. A causal network without reccurence (a tree) has no way to compare objects since there are no horizontal relations and it cannot "look" at backwards relations.

A non-reccurent causal tree has multiple instances of "here" and "now." But without anything to compare a given here/now to the concepts are internally meaningless.

> What is that "something" that is happening all at once?

Not "something". Everything. Like "What is possible to happen? Everything is possible". If you can't divide that possibility by time period, everything possible will happen with probability of 1. How improbable is that universe will happen during 1 trillion years? Very improbable. But if you can't tell in how many years universe will happen, it just will exist.

> but what does that mean for this to "happen all at once"

If you don't have time to make difference between two things happening one after another, they will happen both at the same exact "time".

> If time is defined as the dimension through which something can change then should time not be fundamental to any cosmological theories that extends beyond the Big Bang?

The problem is, time depends on local state of space. More energy/matter in a chunk of space means time is slower relative to other chunks of space. So when you try to go into past with mass in chunk of space increasing into infinity, that time notion breaks.

That's actually helpful.

I can imagine no space and no time.

There is no timeline by which to order cause and effect.

I would argue that the second sentence implies the first isn't true. You can't imagine that there is no time if you're saying things can't happen without time. What I said doesn't mean things can't happen, it just means they happen in a way that doesn't require time to exist (which could be everything happening in the same irreducible instant, or in any order, etc.)

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