The Universe

[Professor Chaos]

Choobus wrote

you're asking what happened before time. There was no before. I don't mean to sound like yoda but it doesn't make any sense to talk about the temporal order of non-temporal events.

Let me clarify: How do we know the big bang was the origin of space/time?

[Professor Chaos]

ocmpoma wrote

I stand (actually, I'm sitting) corrected.

That said, I'll go out on a limb again:

The evidence, Prof, for the lack of space-time and all the other wierdness of the quantum-sized universe, involves a lot of math that the vast majority of people could only have a chance of maybe possibly understanding well if they put in several years of rigorous study.


Richard Feynman: "If you think you understand quantum mechanics, you don't understand quantum mechanics."

Oh, I know. I totally agree. I'm just looking for a microscopic tidbit of explanation.

And while I have no intention to put in "several years of rigorous study," my next question was going to be, and still is: "What are some good books for laypeople to read about the big bang?"

[Choobus]

Professor Chaos wrote

Let me clarify: How do we know the big bang was the origin of space/time?

If it wasn't relativity is totally wrong.

"What are some good books for laypeople to read about the big bang?"

That I can answer (Just remember that the stuff about string theory, especially in the books by Greene, is more than a bit over the top):

Hawking, Stephen:
Illustrated a Brief History of Time, The
Universe in a Nutshell, The

Greene, Brain
Elegant Universe, The: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory
Fabric of the Cosmos, The: Space, Time, and the Texture of Reality

Einstein, Albert:
Relativity: The Special and the General Theory

ocmpoma wrote

"What are some good books for laypeople to read about the big bang?"

That I can answer (Just remember that the stuff about string theory, especially in the books by Greene, is more than a bit over the top):

Hawking, Stephen:
Illustrated a Brief History of Time, The
Universe in a Nutshell, The

Greene, Brain
Elegant Universe, The: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory
Fabric of the Cosmos, The: Space, Time, and the Texture of Reality

Einstein, Albert:
Relativity: The Special and the General Theory

Also check out The First Three Minutes by Stephen Weinberg.

[Rhinoqulous]

I've got a question if any of the actual physicists care to answer.

What exactly does the Multi/Many-Worlds Interpretation bring to the table? I (think I have) a good grasp of the CI, but MWI seems like metaphysical fantasy that Occam's Razor would shred to bits. I've never liked the MWI, probably because it seems similar to the realist version of trans-world identity in philosophy (another theory I think is a bunch of mumbo-jumbo with no basis on anything).

[Professor Chaos]

Choobus wrote

If it wasn't relativity is totally wrong.

I'm starting to feel like a real idiot here, but these were a takeoff on points Dawkins mentioned in The God Delusion. I can't cite right now because I've lent the book to a friend, but does anyone remember what I'm referring to?

By the way, how's the anti-matter project going?

[Professor Chaos]

Evil_Mage_Ra wrote

Also check out The First Three Minutes by Stephen Weinberg.

Thank you both. :thumbsup:

[Choobus]

Rhinoqulous wrote

I've got a question if any of the actual physicists care to answer.

What exactly does the Multi/Many-Worlds Interpretation bring to the table? I (think I have) a good grasp of the CI, but MWI seems like metaphysical fantasy that Occam's Razor would shred to bits. I've never liked the MWI, probably because it seems similar to the realist version of trans-world identity in philosophy (another theory I think is a bunch of mumbo-jumbo with no basis on anything).

That's why the many worlds idea is so unpopular. It is basically the last resort for people who can't accept that quantum processes require observers (I too find this distasteful, but what are you gonna do?). Occams razor is already blunted by the existance of one universe. If one, why not many? Until there is a test it will remain in the backwaters of physics. It is only still talked about now because a few heavyweights have been working on it. It's not quite mumbo jumbo though because some serious mathematics is required to explain it. However, like string theory, that and two quarters will get you 50 c.

Rhinoqulous wrote

I've got a question if any of the actual physicists care to answer.

What exactly does the Multi/Many-Worlds Interpretation bring to the table? I (think I have) a good grasp of the CI, but MWI seems like metaphysical fantasy that Occam's Razor would shred to bits. I've never liked the MWI, probably because it seems similar to the realist version of trans-world identity in philosophy (another theory I think is a bunch of mumbo-jumbo with no basis on anything).

It depends on how you look at it. The many worlds concept would appear to violate Occam's Razor because it proposes a large, possibly infinite number of other universes. On the other hand, many worlds interpretation allows us to cut out some of the troublesome axioms from quantum theory and thus makes it simpler. So the question comes down to which of the possible Occam's Razor's is more beneficial: Simplification of the tangible universe or simplification of the axioms. Simplification of our understanding of the universe has proven successful in the past. If we consider the concept of epicycles or even our understanding of the universe as millions of galaxies, as opposed to one single entity with the earth in the center, we can see that trying to force our equations to fit a simplified universe ultimately had to yield to simplified equations and a more grand and complex universe. So in that sense, the many worlds approach may actually be the correct form of Occam's Razor in this scenario.

With that said, Occam's Razor is a relatively pathetic proof for any kind of scientific theory, particularly when discussing something as complex and misunderstood as cosmology.

I prefer the "shut up and calculate" interpretation of quantum theory. :P

[Choobus]

Sigma wrote

It depends on how you look at it. The many worlds concept would appear to violate Occam's Razor because it proposes a large, possibly infinite number of other universes. On the other hand, many worlds interpretation allows us to cut out some of the troublesome axioms from quantum theory and thus makes it simpler. So the question comes down to which of the possible Occam's Razor's is more beneficial: Simplification of the tangible universe or simplification of the axioms. Simplification of our understanding of the universe has proven successful in the past. If we consider the concept of epicycles or even our understanding of the universe as millions of galaxies, as opposed to one single entity with the earth in the center, we can see that trying to force our equations to fit a simplified universe ultimately had to yield to simplified equations and a more grand and complex universe. So in that sense, the many worlds approach may actually be the correct form of Occam's Razor in this scenario.

With that said, Occam's Razor is a relatively pathetic proof for any kind of scientific theory, particularly when discussing something as complex and misunderstood as cosmology.

It's a false dichotomy in any case. Occams razor is meant to allow you to decide between two similar ideas. If they both give the same results but one is more complicated then you know what to do, but in this case there is no alternative that solves the same problems, so it's moot.

By the way, the many worlds interpretation has fuck all to do with cosmology and everything to do with a universal state vector.

[Rhinoqulous]

Choobus wrote

It is basically the last resort for people who can't accept that quantum processes require observers (I too find this distasteful, but what are you gonna do?).

Wait, isn't it that measurement of quantum processes requires observers? I thought that the CI answer to "is it a particle or a wave?" question was "neither" (and MWI is "both"). Something like an electron, photon, or what-have-you will exhibit wave or particle properties, depending on method of measurement, yet these measurements say nothing about an electron, etc., in-itself. It's a nice, hard limit to our epistemology (IMO). I don't see what benefits the MWI gives to science itself other than expanding the scope of our knowledge.

Occams razor is already blunted by the existance of one universe. If one, why not many? Until there is a test it will remain in the backwaters of physics.

This sounds like the Cartesian Demon/brain in a vat/Deist argument for God. Sure, why not believe in multiple universes. But why not hold the belief we're a brain in a vat (or we're being deceived, or that God exists)? Just because it's a (logical) possibility doesn't mean we should actually entertain it as a significant belief (which is what you probably mean by it's in the "backwaters of physics").

It is only still talked about now because a few heavyweights have been working on it. It's not quite mumbo jumbo though because some serious mathematics is required to explain it. However, like string theory, that and two quarters will get you 50 c.

The mumbo-jimbo was directed at trans-world identity theories. TWI is used to understand certain logical problems (mostly dealing with necessity of properties), and some take these thought-experiments as actual (or highly possible) worlds.

[Choobus]

Rhinoqulous wrote

Wait, isn't it that measurement of quantum processes requires observers?

Well, yes, but it's kind of the same thing. It's all about collapsing wavefunctions. Why do they collapse into a particular eigenstate? "they just do" isn't good enough for some people.

Prof C wrote

Let me clarify: How do we know the big bang was the origin of space/time?

Stephen Hawking wrote

Because mathematics cannot really handle infinite numbers ...the general theory of relativity... predicts that there is a point in the universe where the theory itself breaks down... ...a singularity. In fact, all our theories of science are formulated on the assumption that space-time is smooth and nearly flat, so they break down at the big bang singularity, where the curvature of space-time is infinite. This means that even if there were events before the big bang, one could not use them to determine what would happen afterward, because predictability would break down at the big bang.
Correspondingly, if, as is the case, we know only what has happened since the big bang, we could not determine what happened before-hand. As far as we are concerned, events before the big bang can have no consequences, so they should not form part of a scientific model of the universe. We should therefore cut them out of the model and say that time had a beginning at the big bang.
--Illus. Brief History..., pp 61-62, Bantam Books 1996 ed.

There's also this paper, if you've access to JSTOR.