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At Multiverse Impasse, a New Theory of Scale

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Re: At Multiverse Impasse, a New Theory of Scale

#71

Post by fjolthor »

macspoofing wrote: post #59
axilmar wrote: post #45

Earlier quoted context omitted.

I do not think that it is possible. Any physical system that can be described by a set of mathematical laws is bound to have some axioms that simply cannot be proven within its context. Godel's incompleteness theorems prove that. Hence, we will never get to the bottom of the reality of our universe.

What if we live in a universe/reality where anything that can happen, does happen. And the reason for this state is because it just is.

You mean...the multiverse theory.

Re: At Multiverse Impasse, a New Theory of Scale

#72

Post by smokel »

axilmar wrote: post #45
givan wrote: post #20

I wonder if it's possible to ever find out what our reality is even if we will eventually reach the intellectual and technology necessary because we are part of it and it's probably impossible to have an objective view of the matter.

I do not think that it is possible. Any physical system that can be described by a set of mathematical laws is bound to have some axioms that simply cannot be proven within its context. Godel's incompleteness theorems prove that. Hence, we will never get to the bottom of the reality of our universe.

Your statement that we will never get to the bottom may be true, but the reasoning is flawed.

Gödel's incompleteness theorems are about mathematical theories, not about physical theories. It may well be that for physical understanding a very limited arithmetic is sufficient. Also, there may be statements that are unprovable, but these might turn out to be irrelevant to sufficiently understanding the universe.

Also, an axiom, by definition, can not be proven. The things that are proven are theorems, statements, etc. An axiom is an assumption.

Eventually, it all depends on what level of understanding you want. But Gödel's theorems have little to do with that.

Re: At Multiverse Impasse, a New Theory of Scale

#73

Post by dlevine »

To be fair, this only kills one of the multiverse hypotheses. I'm reading Brian Greene's "The Hidden Reality" right now, and he describes about 8 independent (or semi-independent) multiverse hypotheses. From what I understand (and I'm no physicist), this just provides evidence against the anthropic principle, and the multiverse associated with that line of thinking...

Re: At Multiverse Impasse, a New Theory of Scale

#74

Post by MisterMashable »

There's a very subtle undertone of negativity in this article about physics. Before I get into, William Bardeen is not in the same league as 'Surfer Dude and his E8 Theory of Everything' which throws basic facts about representation theory out the window, coming up with 'todalay boogus' arguments which amazes auntie, mommie and magazine editors but a real physicist would instantly dismiss.

Bardeen is the real deal. His papers are very interesting and feel a bit like reading Sidney Coleman's papers. If you're interested...

http://arxiv.org/find/hep-th/1/au:+Bardeen_W/0/1/0/all/0/1

Is nature scale invariant? So far the answer is absolutely NO but I strongly advise to wait and see. There are many topics that point to some breakdown in scale or reorganizing what we think of space and distance (dualities in string theory, conformal field theory).

OK, now the important thing I want everyone here to realize. You are living through a GOLDEN AGE of physics. You wouldn't think that based on what all the popular magazines tell you. Here's why...

1. Higgs particle - discovered!

2. Inflation - discovered! Denying this one is like denying the Big Bang itself. The evidence is overwhelming and in fact I would list this as the single greatest scientific discovery of all time. The concurrent discovery of gravity waves, quantum gravity and a real life example of a Hawking process only sweetens the deal.

3. Supersymmetry has basically already been discovered IMHO. They aren't announcing anything at CERN and won't until they have so many sigmas under their belt but trust me, it's coming and truth be told, it isn't really so surprising. SUSY physics has always been rock solid from the beginning. The situation is very similar to that before offical Higgs announcement and before someone went knocking on Andre Linde's front door. Many were extremely confident in the Higgs particle a least a year before the official announcement. The BICEP 2 results were even more glaringly apparent than the Higgs results. Many people were walking around the Earth with 'secret knowledge' that inflation theory was correct even 2 to 3 years before the official announcement.

So you are living through EXTREMELY interesting times but you wouldn't know it with all the big science bashing being thrown around.

Re: At Multiverse Impasse, a New Theory of Scale

#75

Post by clusterfoo »

calinet6 wrote: post #41
mSparks wrote: post #11

I don't see why this kills the multi verse theory. Which is a basic conclusion of a 10 dimensional space-time environment that doesn't include mass anyway.

It "kills it" because it's only really appealing if the universe we're in appears extremely unlikely, like it's the "just right" goldilocks balance of cosmic variables that we can't explain, that happened to be the stable ones that resulted in life evolving eventually. If the universe is actually very likely to occur in the state that it's in, then we don't need to use this "vast multiverse where our universe was the…

Naive question (I know nothing about this stuff):

If mathematical logic is a property of our universe, then aren't we again entering the realm of circular logic? i.e: "Given the logical frameworks that are correct in our universe, our universe is very likely."

Unless math is something that somehow exists independently of our physical universe... but then "where" does it come from?

Re: At Multiverse Impasse, a New Theory of Scale

#76

Post by calinet6 »

antimagic wrote: post #55
JackC wrote: post #50

For a heroic attempt to explain this article to laypeople, check out physicsmatt's comments over at Metafilter: "First, for maximum sense-making, read my previous comments here, here, here, and here. I realize that's a lot, sorry. The Universe is complicated. Then, for what follows, recall that to a particle physicist such as myself, there is no difference between lengths and energies (or indeed, any other dimensiona…

Or don't - it's incredibly badly written, in the sense that it often descends into grammatical gibberish, even without worrying about the physics the gibberish is trying to describe.

There's really not that much to understand, and the details aren't that important unless you're living them.

The question boils down to this: are we one of an infinite number of universes that popped into existence that just happened to have the right variables to be stable and result in life? (The anthropic principle, a statistical conclusion, and a philosophical mind-bender...)

Or are we in a single universe whose properties are mathematically aligned in such a way as to be very unlikely to result from chance, even if repeated an infinite number of times? The details of this are interesting, but extremely numerous and complex: basically, Physicists are trying everything.

The latter does not require the hand-wavey wishy-washy existence of an infinite number of non-observable extremely large things, and therefore garners more enthusiasm.

However, if observations conclude that the parameters of our universe are in fact paradoxically perfect, then the idea that we're an evolved observer of one chance universe out of many holds water.

Hence the intense research on how this whole universe thing works. Fun.

Re: At Multiverse Impasse, a New Theory of Scale

#77

Post by playing_colours »

When I became interested in modern physics theories of both quantum and universe level, I found the following book [0] by Max Tegmark to have very good explanations regarding origin and nature of the universe, quantum mechanics, and just interesting stories / facts from the life of physicists.

[0] http://www.amazon.com/Our-Mathematical-Universe-Ultimate-Rea...

Re: At Multiverse Impasse, a New Theory of Scale

#79

Post by calinet6 »

clusterfoo wrote: post #75
calinet6 wrote: post #41

Earlier quoted context omitted.

It "kills it" because it's only really appealing if the universe we're in appears extremely unlikely, like it's the "just right" goldilocks balance of cosmic variables that we can't explain, that happened to be the stable ones that resulted in life evolving eventually. If the universe is actually very likely to occur in the state that it's in, then we don't need to use this "vast multiverse where our universe was the…

Naive question (I know nothing about this stuff): If mathematical logic is a property of our universe, then aren't we again entering the realm of circular logic? i.e: "Given the logical frameworks that are correct in our universe, our universe is very likely." Unless math is something that somehow exists independently of our physical universe... but then "where" does it come from?

I have no idea, really.

My hunch is that mathematics is more than universal; truths hold regardless of which medium of calculation is used to conclude them.

In any case, our conclusions about our own universe at least hold within our own universe, and are therefore still very useful for our own understanding thereof.

Re: At Multiverse Impasse, a New Theory of Scale

#80

Post by im3w1l »

protonfish wrote: post #60
givan wrote: post #20

I wonder if it's possible to ever find out what our reality is even if we will eventually reach the intellectual and technology necessary because we are part of it and it's probably impossible to have an objective view of the matter.

There is this belief propagated among physicists that smaller scales somehow have more to do with reality. I have never been presented with logic or evidence that convinced me that an electron is somehow more "real" than a molecule or a person or the solar system or the observable universe. I wish the word "reality" would stop being thrown around without justification. "Fundamental" might be a more appropriate term.

It easier to get a detailed understanding of the universe, by observing what happens in extreme cases. The very small. The very big. The very heavy. The very energetic. The very quick.
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