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  #51  
Old 04-21-2017, 08:58 AM
Lumpy Lumpy is offline
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Scientific American had an article pointing out that the fine-tuning argument overlooks that there might be combinations of alternate constants that could allow for life to exist.
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  #52  
Old 04-21-2017, 10:52 AM
SamuelA SamuelA is offline
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Life as we know it is based on atoms. Is there any way for an atom to catalyze the creation of an identical atom? It's not the gravitational waves themselves which need to be reproduced; it's the patterns in them.
For the purposes of chemical reactions, different atoms of the same element are indistinguishable, and this is nearly always true even in the case of differing isotopes.
Only the outer electron shell matters in most cases.

I guess when I said "identical" I meant "Functionally indistinguishable". So by what mechanism can gravity ways accomplish, this even in theory? Give the simplest case you can think of.
  #53  
Old 04-21-2017, 11:57 AM
Chronos Chronos is offline
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All gravitons are also indistinguishable. What you would have would be a Universe entirely filled with gravitational waves. Each wave would pass through any given region at c, and quickly leave for parts unknown. But new gravitational waves would also be entering the region at the same rate, so there would still always be gravitational waves present. Meanwhile, the waves would be interacting with each other, and patterns would emerge within the waves. These patterns would also be moving, but not necessarily at c: It's possible, for instance, to have sound waves propagating through a gas of massless photons, and those sound waves travel at 1/3 c.

Now, I realize that there's a heck of a big step from "self-interacting patterns which propagate at less than c" to "life". But then, there's a heck of a big step to our kind of life, too. And once you have the self-interacting patterns, it's at least possible.
  #54  
Old 04-21-2017, 01:32 PM
Riemann Riemann is online now
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Scientific American had an article pointing out that the fine-tuning argument overlooks that there might be combinations of alternate constants that could allow for life to exist.
Once again, to be clear, I don't think physicists would use the term fine-tuning argument for anything. That expression tends to be associated with the "we can't explain this, therefore God" crowd.

There is a fine-tuning problem in cosmology. But that problem does not rest on excluding alternate combinations of parameter values (perhaps there are very many such combinations) that might allow for "life" in the broadest sense. The question is what proportion of parameter values have this property? And if string theory's lack of constraint on parameter values is correct, it seems to be true that the overwhelming majority of combinations of parameter values are inconsistent with life.

Hence the multiverse idea. Or, if ours is the only universe, the need for an explanation for why our apparently "lucky" set of values occurred - perhaps some other as-yet unknown model.

Last edited by Riemann; 04-21-2017 at 01:37 PM.
  #55  
Old 04-21-2017, 04:25 PM
Irishman Irishman is offline
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But don't confuse this with the real fine-tuning problem in physics. When physicists call this a "problem" it does not imply that it's paradoxical or insoluble of that we must turn to God. It's just a problem in the sense that we don't know which of several possible naturalistic explanations is the correct resolution. One of the possible resolutions is the multiverse and the anthropic principle.
Okay, so what you're saying is that in physics, it's a problem of why is the universe the way it is rather than a question of why are we here.
  #56  
Old 04-21-2017, 05:02 PM
ftg ftg is offline
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All gravitons are also indistinguishable.
Photons have wavelength and spin angular momentum which can be used to distinguish them a bit. Gravitons don't have these properties or are you excluding such properties in terms of distinguishability?
  #57  
Old 04-21-2017, 05:09 PM
Riemann Riemann is online now
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Okay, so what you're saying is that in physics, it's a problem of why is the universe the way it is rather than a question of why are we here.
I'm not quite sure what distinction you are drawing.

Our universe has a set of parameter values that allow life to exist. But we have no model for making universes that constrains the parameters; our best models (our only models) allow a vast range of possible parameter values, the overwhelming majority of which are not compatible with life.

Under these circumstances, the anthropic principle is sufficient to explain why we are sitting here looking at a universe compatible with life, but only if universes with all possible parameter values do actually come into existence.

But the multiverse hypothesis has a deeper foundation than just this point, it has a well-developed theoretical basis - it arises naturally from these models of inflation & string theory. (Without any empirical support whatsoever, of course.)

https://en.wikipedia.org/wiki/Andrei...otic_inflation

https://en.wikipedia.org/wiki/Multiverse

Last edited by Riemann; 04-21-2017 at 05:14 PM.
  #58  
Old 04-21-2017, 05:12 PM
Snarky_Kong Snarky_Kong is offline
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If we live in a multiverse, the question is essentially meaningless - How can you take a percentage of infinity?
Easily.

I flip a fair coin infinite times. 50% of the time it will be heads.
  #59  
Old 04-21-2017, 06:11 PM
Trinopus Trinopus is offline
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Exactly so. In math, it's called "probability density," which is just a fancy way of saying that, even among infinite sets, some subsets are "bigger" than others.

If you rolled a pair of dice an infinite number of times...yes, you'd get an infinite number of 7s and an infinite number of 2s (snake-eyes.) Nevertheless, there will be six times as many 7s as there are 2s, or, perhaps more accurately, the distribution of the 7s is six times as dense as the distribution of 2s.
  #60  
Old 04-21-2017, 06:34 PM
Chronos Chronos is offline
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Again, it's sometimes possible to speak meaningfully of probabilities in infinite sets. Not always, and not necessarily here.
  #61  
Old 04-23-2017, 12:43 PM
Irishman Irishman is offline
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I'm not quite sure what distinction you are drawing.
You've described the physics issue. The religious is about justifying God's existence by looking at why humans exist. "Humans shouldn't exist; therefore, God exists."
  #62  
Old 04-23-2017, 12:52 PM
Riemann Riemann is online now
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You've described the physics issue. The religious is about justifying God's existence by looking at why humans exist. "Humans shouldn't exist; therefore, God exists."
I'd say the religious argument is simply an instance of the God-of-the-gaps fallacy. Before there was a naturalistic account of lightning and thunder, it was attributed to irascible gods. Until we had Darwin's naturalistic explanation for biological design, it was attributed to God's creation. At present, we do know the correct naturalistic resolution to the fine-tuning problem in physics - therefore God did it.
  #63  
Old 04-27-2017, 12:43 PM
Blue Blistering Barnacle Blue Blistering Barnacle is offline
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Regarding Anthropic principle, why is this not a tautology: "We observe the universe we observe."?

I've heard it said that Hoyle invoked the anthropic principle to predict the existence of a Beryllium resonance to explain the prevalence of carbon. "Carbon can't be made in abundance without this resonance. Life as we know it (and Hoyle specifically) would not exist without carbon. But Hoyle exists. Therefore the resonance exists."

https://en.wikipedia.org/wiki/Triple-alpha_process

But this argument could be shortened to "Carbon can't be made in abundance without this resonance. We observe large amounts of carbon. Therefore the resonance exists."

I mean, if it was the existence of molybdenum he had to explain, he wouldn't say he resorted to the anthropic principle, would he...?
  #64  
Old 04-27-2017, 01:12 PM
Riemann Riemann is online now
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Regarding Anthropic principle, why is this not a tautology: "We observe the universe we observe."?...
Sure, and natural selection is also a tautology. Yet nobody before Darwin realized the profound implications, that it could account for apparent biological design without a creator.

The importance of the anthropic principle is that, in conjunction with the multiverse hypothesis, it is one possible resolution to the fine-tuning problem in physics, as described above in the thread. The anthropic principle is not just "we observe the universe we observe", it is "if all possible kinds of universe exist, then self-aware beings will exist in the subset of of universes that are compatible with the evolution of self-aware beings".

Last edited by Riemann; 04-27-2017 at 01:15 PM.
  #65  
Old 04-27-2017, 03:40 PM
Blue Blistering Barnacle Blue Blistering Barnacle is offline
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Sure, and natural selection is also a tautology. Yet nobody before Darwin realized the profound implications, that it could account for apparent biological design without a creator.

The importance of the anthropic principle is that, in conjunction with the multiverse hypothesis, it is one possible resolution to the fine-tuning problem in physics, as described above in the thread. The anthropic principle is not just "we observe the universe we observe", it is "if all possible kinds of universe exist, then self-aware beings will exist in the subset of of universes that are compatible with the evolution of self-aware beings".
I'll agree that "survival of the fittest" is a tautology. Maybe it betrays a prejudice, but I can really feel that this little statement gives me much more, providing huge insight into many facets of life on earth (and presumably the cosmos). And with extensions into computer science, etc.

"We observe the universe we observe" just doesn't do much for me, except (maybe) requiring that I envision a multiverse (beyond observation). I am allowed to envision a multiverse without invoking anthropic principle, I suppose. Maybe it encourages me to consider a multiverse, where before I was puzzling about why my (solitary) universe was so "comfy".

I guess I just don't "feel it" with anthropic principle, whereas I really do "feel it" with natural selection.
  #66  
Old 04-27-2017, 04:05 PM
Chronos Chronos is offline
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It's worth noting here that there are multiple different anthropic principles, applying on different scales. At its simplest, I think it's really more of an exception to a principle than a principle itself. The Copernican Principle says that where we happen to be in the Universe isn't special, and so observations we make here probably apply to the whole Universe. The Anthropic Principle, however, points out that where we happen to be is special, at least to the extent that where we happen to be is a place capable of supporting life, whereas most of the Universe is not, and so our local observations might differ from the Universe as a whole in ways relevant to the formation of life.

As an example, if I measure the local density of matter, I find that it's on average a few tons per cubic meter. But I can't conclude from that that the density of matter in the Universe as a whole is that high: In fact it's much lower. That's because such a locally-high density of matter is necessary for the formation of life as we know it.
  #67  
Old 04-27-2017, 04:12 PM
Riemann Riemann is online now
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I'll agree that "survival of the fittest" is a tautology. Maybe it betrays a prejudice, but I can really feel that this little statement gives me much more, providing huge insight into many facets of life on earth (and presumably the cosmos). And with extensions into computer science, etc.

"We observe the universe we observe" just doesn't do much for me, except (maybe) requiring that I envision a multiverse (beyond observation). I am allowed to envision a multiverse without invoking anthropic principle, I suppose. Maybe it encourages me to consider a multiverse, where before I was puzzling about why my (solitary) universe was so "comfy".

I guess I just don't "feel it" with anthropic principle, whereas I really do "feel it" with natural selection.
You first need to understand the nature of the fine-tuning problem in physics. The merits of the proposed solution will not be apparent unless you understand the problem. The problem is that we can't find any models that constrain the parameters of the universe. See posts 36, 38,50, 54, 57.

So, one proposed solution to the fine-tuning problem in physics is the multiverse, and then the anthropic principle is sufficient to explain why we seem to live in a universe with Goldilocks parameters.

Last edited by Riemann; 04-27-2017 at 04:14 PM.
  #68  
Old 04-27-2017, 06:25 PM
Trinopus Trinopus is offline
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Regarding Anthropic principle, why is this not a tautology: "We observe the universe we observe."? . . .
It's slightly more profound than that: it tells us something about our universe. Our universe is (at least) complex enough for observers like us to exist in it.
  #69  
Old 04-27-2017, 07:44 PM
clairobscur clairobscur is offline
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I hate the concept of the multiverse. Not only does it take away free will, it takes away any point to existence.
This. I totally hate the concept (even though it still might be true).

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One might suggest that without connectivity and communication *between* the various incarnations of a multiverse, that what you do DOES matter - because you will never see the alternative acts, nor their consequences. Thus, morality and free will are preserved.
How are they preserved? You do every single thing that can physically be done. It just so happen that this version of you is the one that posted a message on the SDMB rather than the version that balanced a bottle of ketchup on his nose.

How is free will and morality preserved if you inevitably both give the child a candy and bash his head with a hammer? You *will* do both. There will be a you that gives the candy and a you who blugeons the kid. It's inescapable. How each being unaware of the other existence preserves morality and free will?

During the next minute you will decide to give all your possessions to feed starving children and you'll also decide to murder your grandmother for the inheritance money. And you'll decide to balance a bottle of ketchup on your nose. How could we judge your "morality", given that?

Last edited by clairobscur; 04-27-2017 at 07:45 PM.
  #70  
Old 04-27-2017, 09:27 PM
Chronos Chronos is offline
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There may be universes where you give the kid a piece of candy, and universes where you bash the kid's head in... but there aren't equal numbers of universes with those two outcomes (and yes, this is a situation where we can meaningfully compare the numbers of each). The number of universes in which you don't hammer the kid (I hope) vastly outnumber the ones in which you do. By how much? That's determined by your free will.
  #71  
Old 04-27-2017, 09:39 PM
Riemann Riemann is online now
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...That's determined by your free will.
You slipped that in there under the radar.

Has anyone worked out a satisfactory account of QM probabilities in the Many Worlds interpretation?
  #72  
Old 04-28-2017, 01:46 AM
clairobscur clairobscur is offline
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There may be universes where you give the kid a piece of candy, and universes where you bash the kid's head in... but there aren't equal numbers of universes with those two outcomes (and yes, this is a situation where we can meaningfully compare the numbers of each). The number of universes in which you don't hammer the kid (I hope) vastly outnumber the ones in which you do. By how much? That's determined by your free will.
How so? At the precedent moment, my thoughts, actions, choices, etc.... were also any of my possible states of mind, and the moment before too, and so on, since my birth. So, the number of universes were I don't bash the head of the child just depends on the path the me in this universe happens to have followed. I really don't see where there is room from free will here. Maybe there are anyway less universes where I can be born with a significant tendancy to bash children heads, but it's just dependant on my original genetic make-up, since I follow all possible paths from the moment of conception.

In some universes, I'm going to leave ande bash a random child head just to prove my point in this argument. It is certain that I will do that because it's possible. How guilty are the versions of me that will do that given that they necessarily must exist? It seems to me that they just happen to be on the wrong branch, having lost the "die roll". If an action is unavoidable, how can it be "free"?

Last edited by clairobscur; 04-28-2017 at 01:49 AM.
  #73  
Old 04-28-2017, 06:21 AM
Chronos Chronos is offline
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Most of the other people in this universe also don't bash children's heads in. The vast majority, in fact, such a vast majority that, even out of seven billion people, it's still noteworthy when someone does it. Did they all just happen to be in the universe where they don't kill children? It seems much more rational to conclude that the probability of a human being in such a state that they'll kill children is much less than the probability that they won't. How can we describe this fact that humans usually don't kill children?
  #74  
Old 04-28-2017, 06:51 AM
clairobscur clairobscur is offline
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Most of the other people in this universe also don't bash children's heads in. The vast majority, in fact, such a vast majority that, even out of seven billion people, it's still noteworthy when someone does it. Did they all just happen to be in the universe where they don't kill children? It seems much more rational to conclude that the probability of a human being in such a state that they'll kill children is much less than the probability that they won't. How can we describe this fact that humans usually don't kill children?
I guess you would say "morality". But I disagree. Because the concept of morality, for me at least, requires the possibility to make a choice. And making all the possible choices is the same as making no choice at all.

I am who I am but put a child besides Me and the next second, even though the vast majority of future me won't do anything notable, some will *inevitably* kill the child, in various ways, for various reasons (all possible ways, all possible reasons). Since the versions of me who kill the child were, one second before, exactly the same person as the versions who don't kill the child, and since these killer versions *must exist*, how can you say that morality is at play? What is morally wrong with these child killer versions? One second before they were perfectly moral people, not inclined to kill anybody. But somehow the fact that the laws of the multiverses *put them inevitably in existence* makes them morally guilty?

If we replace these laws by god, for instance : in one second god will create in our office someone who has an irrepresible desire to kill the coworker next to me (no child around). How can this person, created specifically with the mindset required to kill my coworker and the opportunity to do so can be morally guilty if he does? Wouldn't *god* be morally responsible for creating this person? I don't see any difference with the future versions of myself that will inevitably kill my coworker because the physical laws of the mutiverse *require* their existence.

Last edited by clairobscur; 04-28-2017 at 06:52 AM.
  #75  
Old 04-28-2017, 07:08 AM
Half Man Half Wit Half Man Half Wit is offline
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Photons have wavelength and spin angular momentum which can be used to distinguish them a bit. Gravitons don't have these properties or are you excluding such properties in terms of distinguishability?
Gravitons do have wavelength and spin (in fact, they have more possible spin states than photons), but that's not the issue: you can build complex things out of a reservoir of identical things---for instance, you can use a cellular automaton composed out of repetitions of the same basic cell perform universal computation. In principle, there doesn't seem to be any obstacle to something like a computer made of gravitational waves (and I've toyed with the idea of advanced civilizations encoding themselves into gravitational wave patterns for a science fiction story...).
  #76  
Old 04-28-2017, 08:46 AM
Blue Blistering Barnacle Blue Blistering Barnacle is offline
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This. I totally hate the concept (even though it still might be true).



How are they preserved? You do every single thing that can physically be done. It just so happen that this version of you is the one that posted a message on the SDMB rather than the version that balanced a bottle of ketchup on his nose.

How is free will and morality preserved if you inevitably both give the child a candy and bash his head with a hammer? You *will* do both. There will be a you that gives the candy and a you who blugeons the kid. It's inescapable. How each being unaware of the other existence preserves morality and free will?

During the next minute you will decide to give all your possessions to feed starving children and you'll also decide to murder your grandmother for the inheritance money. And you'll decide to balance a bottle of ketchup on your nose. How could we judge your "morality", given that?
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There may be universes where you give the kid a piece of candy, and universes where you bash the kid's head in... but there aren't equal numbers of universes with those two outcomes (and yes, this is a situation where we can meaningfully compare the numbers of each). The number of universes in which you don't hammer the kid (I hope) vastly outnumber the ones in which you do. By how much? That's determined by your free will.
http://www.smbc-comics.com/comic/multiverse
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