Comment by calinet6 | Hacker News Reader

Comment by calinet6 | Hacker News Reader

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It's actually not that at all.

This image tells it all: https://d262ilb51hltx0.cloudfront.net/max/953/1*QXypiHUwjJZr...

What he was saying is, if there was just 1 gram per cubic cm less mass in the original universe, then it would expand too quickly to form any complex structures and the universe as we know it would not exist. And if it was just a few grams per cubic cm more massive, then it would collapse immediately as in the original question.

The reason our universe did not immediately collapse is not a mystery. It was a tiny amount less massive than would be required for such a collapse.

The reason it was perfectly on the line is no mystery whatsoever: if it were one gram over, it would collapse, and we would not exist, and thus we would not be asking the question. Same if it were one gram less; the universe would be too sparse for life to organize.

This is not a miracle or a mystery, it's simply fact. Billions or trillions of universes might have sprung into existence over billions or trillions or perhaps even infinite aeons of time, each with different masses and parameters of physics.

The one that produced an observer was observed. That's us, and that's it. No miracle, no mystery.

It's like someone winning a lottery. The chances of a specific individual winning are next to nothing, but the chances of anyone winning are 100%. If a news crew then goes and finds the winner, they will surely find an astounded, surprised, and very lucky feeling person. But the news crew will not be surprised, since their observation is entirely expected and even guaranteed.

Humanity is both the winner and the news crew in this situation, by the simple property of our ability to observe our own existence.

This is called the anthropic principle. It also applies with zero modification to the question of why Earth appears to be such a perfect planet to support human life, especially as we begin to discover that there are literally trillions of planets in our universe. We should not be surprised that we observe the one that happened to have the conditions conducive to the evolution of a sentient observer. But you could be forgiven for feeling very lucky that you're one of them.

I like this sentence...

> The one that produced an observer was observed.

I wonder if it applies in other contexts, specifically, er, quantum decoherence?

You need to be careful with this line of reasoning if you mean what I think you mean.

I've found that when speaking with laypeople about quantum decoherence, a very common misconception comes from the use of the word 'observer' (see: http://www.imdb.com/title/tt0399877/ ). If you say "A quantum system can be in a superposition until its wave function is collapsed when it's observed.", a layperson can easily interpret that to mean that a sentient being needs to look at and take note of the system for it to count as being observed, when in fact all that is required is that an external particle interact with the system and carry away some information (energy).

There's nothing special about humans (and their ability to observe) in this context.

Yes. Observer in my post above specifically refers to a sentient being; observer in quantum computing specifically does not. However given the context, the two are (very) roughly similar. One could (again, very roughly) think of the universe as a giant quantum computer solving for the variables that lead to sentience. The observers are inside the system in that case, but it's the same idea: create every possible state and select for the solution that solves the problem.

Only an analogy, of course.

I was just thinking how similar the anthropic principle is to the general concept behind quantum computing (to the best of my limited knowledge: create a quantum superposition of states and the one which solves the problem is the solution). Uncanny.

That's very much not what quantum computing is about, sorry.

It does not do exponential parallelism by trying many things at once. What it does do is create exponentially many paths, while some of which interfere with one another destructively. When you observe the system, then, some paths will have probability zero even though they have non-zero complex amplitudes associated with it.

Scott Aaronson's "Limits of Quantum Computers" to the rescue: http://www.cs.virginia.edu/~robins/The_Limits_of_Quantum_Com...

It was indeed a very rough analogy. Not saying we can equate them by any means. Great to learn more about quantum computing though, thank you for the clarification and the link!

Doesn't this assume that "we" had multiple chances to exist? That if a universe existed that collapsed "we" would just move on to the next universe until we settled on one that we could exist in? This almost sounds like we were rejecting universes.

Wrong perspective. "We" had nothing to do with it. The lottery analogy implies a selector, but it's only a model: in reality, this is an autonomous, unselecting, random distribution, and "we" just happen to be in it and able to describe it from within. We had no bearing on whether we were created or not, nor which universes were 'rejected.' (The 'rejected' ones surely still exist, with the exception of the fact that perhaps they didn't produce an observer to know about them).

"We" reject other universes because "we" observe this one, and "we" don't observe the others. There may not be others. There could be infinite others. We don't know; we know only what we see, and that's a universe in which we exist. The trait of observation means only that an observer exists. It's a tautology, and does not imply anything else.

This is similar to consciousness (another analogy): you appear to be an isolated observer of the world, when in fact there are over 7 billion others, who also are themselves isolated observers of the world. The fact that you can observe your own existence does not mean you are selected or that any selection process took place that resulted in you specifically. Your consciousness came afterward; your ability to understand it even later.

Consciousness is, in fact, quite common and ordinary. It carries no meaning other than what it is. Ascribing meaning to the trait of one's own consciousness is just a human construct. It is an illusion; a by-product of consciousness itself.

As with the universe. The universe which created us is not special. It's simply the one in which we find ourselves. "Special" is what we might call that, but only from our (limited, tiny, inconsequential) perspective. In the greater reality, it is simply a thing that happened. Other universes with different parameters may have other sentient beings in them with the same dilemma. They are not selected for either; they simply happen to have conditions which resulted in the evolution of beings who can see and think and feebly understand where they are.

The purpose of all this is up to you. The most likely explanation is that there is not a purpose to the conditions from which our consciousness came about. It is likely simply one universe in an infinite number in the unfathomably large and complex—yet simple—reality that is. We may never know what is outside our universe, but that is the reason for its continued study.

Or, as good as any:

“We are a way for the cosmos to know itself.” - Sagan

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