The “sensible anthropic principle” says that certain apparently unusual features of our environment might be explained by selection effects governing the viability of life within a plethora of diverse possibilities, rather than being derived uniquely from simple dynamical principles. Here are some examples of that principle at work.
- Most of the planetary mass in the Solar System is in the form of gas giants. And yet, we live on a rocky planet.
- Most of the total mass in the Solar System is in the Sun. And yet, we live on a planet.
- Most of the volume in the Solar System is in interplanetary space. And yet, we live in an atmosphere.
- Most of the volume in the universe is in intergalactic space. And yet, we live in a galaxy.
- Most of the ordinary matter in the universe (by mass) consists of hydrogen and helium. And yet, we are made mostly of heavier elements.
- Most of the particles of ordinary matter in the universe are photons. And yet, we are made of baryons and electrons.
- Most of the matter in the universe (by mass) is dark matter. And yet, we are made of ordinary matter.
- Most of the energy in the universe is dark energy. And yet, we are made of matter.
- The post-Big-Bang lifespan of the universe is very plausibly infinite. And yet, we find ourselves living within the first few tens of billions of years (a finite interval) after the Bang.
That last one deserves more attention, I think.
Well, I can think of two potential problems with the Fecund universe. The stronger gravity is, the more black holes form. This would predict, then, that the strength of gravity in most universes containing life would be just barely small enough to contain life (after all, if gravity is so strong that only black holes form, then no life can form either). Granted, I’m not sure what the numbers are here, but it would, in principle, not be that difficult to calculate within Smolin’s model the probability of a gravitational constant given the existence of planets. I rather doubt that this would result in our universe being likely.
The second potential problem is the existence of vacuum fluctuations. I rather expect that the number of black holes that are produced as vacuum fluctuations vastly exceeds the number of semi-stable black holes. Therefore, if Smolin is right about the interiors of black holes being other universes, then it seems to me that he is unlikely to be correct about universes that create black holes from gravitational collapse being preferred.
Granted, I haven’t examined the idea much at all, it just naively seems to be unlikely to me. By contrast, the idea of the string theory land scape seems much more plausible, given the possibility of future-eternal inflation.
BTW folks, what genuine basis do we have for actually figuring mechanisms “behind” physical laws, and what would change them? You can make up (that’s what it is) a construct that would be able to change and pretend you’re getting different constants out of that, but that looks suspicious in the grand scheme. I know that gravity might be tunable etc, but the whole structure of things is just wide open. It can’t be some essential structure that’s just the default for “existing” in some sense. The better thinkers about fundamental issues (framing issues) can tell you, “existence” is not a predicate, and there is no way to tie it logically to any particular manifestation.
From whence “the landscape”? When people come up with foundational entities like strings, they are just working back from whatever we see around to some concept that fits. It’s almost a circular argument, and we can imagine entities in something completely different imaging the alternative “building blocks” that would fit into their reality etc. Yeah, we don’t have access to such entities, but neither to the realms nearly like ours (and where does it end?) needed to make sense of legally distinguished other universes either. We are not starting a priori and working back up to what a or the universe must be like. That’s just the breaks.
Neil B.,
The typical mechanism for producing different low-energy physical laws in different regions is spontaneous symmetry breaking. The analogy that is usually used is that of a ferromagnet. In a ferromagnet, there is a tendency for the magnetic moments of the various atoms to line up with other atoms nearby at low temperatures. At high temperatures, the magnetic moments will be pointing in random directions, bouncing all over the place. As the temperature is lowered, the magnets will start to line up. But they don’t do so uniformly: they will line up in one direction in one region, and an entirely different direction in another region. This is because the magnetization happens slowly: it starts when a few atoms have moments that, due to random chance, tend to line up, or around some sort of impurity. Once they start to line up, the pattern spreads, and the region magnetizes. But more than one region will do this at any given time, so eventually it’ll run into another spreading region, and since neither direction is preferred over another, the magnet itself will stabilize with a large number of domains with magnetic fields pointing in different directions.
A similar setup is typically thought of for producing the low-energy physical laws in our present universe. The idea is basically that certain of the constants we observe are produced as a result of one field or another taking a particular value, not because that value was somehow special, but because the neighboring points also took that value. In string theory, one way of thinking of this is by examining the different ways in which we can compactify the higher dimensions.
But, in any case, I think we do expect that there must be some fundamental structure that just exists. I don’t think the universe could make sense were this not the case.
Jason, you have a point, and the discussion was good middle-brow description (like I usually need) of cutting edge fundamental physical theory. That could well be how the fundamental structure “that exists” works, but it’s hard to know since how can we experimentally produce for testing, regions with literally different low-energy laws (not to be confused with the non-linear response of given matter in space to higher energy etc.) If you have writings out there about this issue, yours or favorites from others, please leave some links or etc.
Now, what I meant about fundamentals was: sure there is a structure that just exists, behind everything else. However, logic itself doesn’t give any reason for that structure to be inherently natural to “existing” versus another, it is a given “put in by hand” as they say. (I mean, even the structure like strings that would underlie different expressions of physical law, not merely a given set of laws and constants. Despite their flexibility and power over some laws, the strings still have laws of their own, a certain way to be. They are a little patch carved out of “all possible descriptions.”)
As I have explained before, existence is not a predicate and cannot even be logically defined, such as could separate described model universes into “the ones that exist” and the ones that don’t. Check “modal realism” on Wikipedia etc. Ironically I don’t actually believe in MR. It’s just that either “everything exists”, or, something outside logical necessity must be responsible for the limited set of existing things being as they are. You can imagine that “something” as you wish.
sure there is a structure that just exists, behind everything else. However, logic itself doesn’t give any reason for that structure to be inherently natural to “existing” versus another, it is a given “put in by hand” as they say. (I mean, even the structure like strings that would underlie different expressions of physical law
And after a while you run into the basic problem with reductionism – A depends on B, and B depends on C, and… is it turtles all the way down for ever and ever amen? Or as deep as you’re willing to look? How far down do you go before you can’t reduce anymore? At some point you go beyond the limits of observation (like string theory), and you’re using heuristic mental constructs to explain things. In other words, you’ve reduced realism to idealism.
Neil B.,
One of the interesting things about spontaneous symmetry breaking is that it can, indeed be tested. And hopefully will be quite soon. It is, for example, a fundamental aspect of the standard model of particle physics, which has so far been confirmed to a tremendous degree. And the most interesting prediction of this model has yet to be confirmed: the existence of the Higgs boson. It is my hope that if the Higgs is discovered at the LHC, that we will obtain much more direct evidence of the existence of a spontaneous symmetry breaking event in our distant past.
Now, as for the existence of a fundamental theory, I have to ask, why can’t there be a fundamental reason why a certain theory is the correct one? We certainly don’t know of any such fundamental reason, but that doesn’t mean it isn’t there. One fundamental reason that would satisfy me, however, would be if we were to show that there exists only one mathematically consistent theory of the universe, and there is a principle where everything that can happen does happen. This would be a fantastically difficult thing to show, and we are not even close to doing so. It may also be entirely wrong. But in any case I think we should expect that were we to discover the most fundamental theory of the universe (something rather unlikely to happen in the lifetime of anybody currently alive), that we would also find that there is a deeply interesting and simple reason why it is the fundamental theory of the universe.
In other words, at some point, we should expect the most fundamental theory of the universe to explain itself. I don’t know if mankind will ever find this theory, but one can always hope. In the mean time, we should continue to do what we have been doing: expanding our knowledge through further observation and experiment, and expanding our awareness of what might be by asking as many “What if?” questions as we can pose.
Oops, I don’t think I worded that first paragraph properly, expressing far too much certainty. Sorry about that. My field of study is not quantum field theory, so I cannot say with certainty that this particular aspect of the standard model will be tested soon. What I can say is that it is a significant aspect of the theory, and the discovery of the Higgs would be a tremendous step forward in confirming the theory. I’m not quite certain precisely how this would impact the testing of whether or not there actually was spontaneous symmetry breaking, but I expect that it will lend significant evidence in support of such an event.
That out of the way, there is potentially another method of testing for spontaneous symmetry breaking, that has so far yielded a null result. Specifically, spontaneous symmetry breaking events tend to leave what are called defects, and those defects are dependent upon the dimensionality of the space. Imagine, for instance, a flat plain. On this plain is an array of pencils, each with one end attached to the plane. We also have a bunch of springs connecting the other ends of the pencils to one another. Thus, we have a situation where if we drop one pencil down in one direction, the pencils nearby will tend to also fall down in a similar direction.
Thus the obvious stable low-temperature configuration of a region of this plane is all of the pencils pointing in the same direction. There is, however, another configuration: imagine one pencil standing straight up, with all of the pencils around it pointing radially outward. This one standing pencil is stable because it is being pulled in all directions equally, and those around it are stable because they have pencils around them pointing in nearly the same direction as themselves. This is what is known as a defect.
In three dimensions, we tend to get defects that are like long strings (not to be confused with the strings from string theory). Now, cosmic inflation tends to dilute such things, so we don’t necessarily expect to be able to find any. However, if we could find a cosmic string, it would be a dramatic confirmation of the existence of at least one spontaneous symmetry breaking event happening in our past.
sure there is a structure that just exists, behind everything else. However, logic itself doesn’t give any reason for that structure to be inherently natural to “existing” versus another, it is a given “put in by hand” as they say.
Not necessarily if there is an inherent imbalance in the energy of the universe then there exists a natural, impetus that will drive the structure perpetually “down-hill” in a purely natural effort to to reconcile the disequilibrium.
How it got there?… I dunno, but that isn’t a factor since we have no evidence that “nothing” can or ever did exist, so I can’t assume that this imperfect energy ever didn’t exist, since I can justify that it is plausible that it has.
Why is the energy less than pure?… I don’t know that either, but I know that you can’t square the circle and no two snowflakes or molocules are exactly alike, so I have no evidence that there should be any kind of absolute symmetry in the energy either, so your questions require assumptions about stuff that isn’t observed to be possible.
In this context it’s “existing versus”… nothing that you can justify should be expected.
Neil,
When people come up with foundational entities like strings, they are just working back from whatever we see around to some concept that fits.
Mathematics is suppose to be the foundation of the natural world?:)
Anyway the landscape is attractive to some while undestanding fully that you are pushing perspective back to the micoseconds of our universe. “Island” may be describing the potential, of hills and valleys?
Then, we see perspective forming around our collider uses. One has to think what use this method if it did not imply some connection to the cosmological formulation of our early universe?
Is “dimensional perspective” possible within the confines of these collisions processes? Within the universe and why not?
The problem with the Fecund Universe concept, which I told everyone I spoke to about Cosmology immediately after Smolin’s publication, was that evolutionary biology shows how sexual reproduct explores genome space exponentially faster than asexual revolution. Cosmos budding off daughter cosmos is asexual reproduction. Fine tuning of physical constants to anthropic values is reached if we can figure out a way to have TWO universes in the landscale combine to create a daughter cosmos, with some combination of the physical constants of each, plus some random mutation due to, whatever, quantum uncertainty in superspace. Sexual reproduction of universes — that gives a new meaning to “Big Bang.”
The Establishment approach to eliminating crackpots is to restrict to authors of refereed papers, and further, in the disciplines in which they are published (to eliminate the phenomenon of an expert in one field pontificating spuriously in another field).
That eliminates a small number of famous rejected but signifcant papers, and lets in a few goofy things that referees mysteriously okayed, but is generally useful to, say, academic bloggers.
The background of my article “Human Destiny and the End of Time”, in the magazine Quantm (edited by a PhD Chemist, by the way) and published years before Bostrom’s rediscovery, was my own prior publications on extrapolating the advance in computing power.
Jonathan V. Post, “Quintillabit: Parameters of a Hyperlarge Database”,
Proceedings of the Sixth International Conference on Very Large
Databases,
Montreal, Canada, 1-3 October 1980
The above coined the term “1 Shannon = 1 mole, Avogadro’s number, of bits.”
Simulating a person, or the entire universe, is estimated in Shannons. How many Shannons do you think it takes to simulate the obervable universe to, say, femtometer and femtosecond resolution?
My PhD work included analyses of how many bytes per second are processed in a single cell (bacterium or yeast) and extrapolating to how many computations per second are needed to simulate an entire organism in ultra-high resolution. The chapters of that dissertation, arguably the first ever on what became Nanotechnology, were read worldwide when repackaged as refereed papers, and expecially intrigued scientists at U. Moscow and U. Leningrad, which the State Department preferred I not correspond (this being the Cold War, and my doing highly classified work for Boeing, Rockwell, Lockheed, Army, Navy, and Air Force).
The government explanation to me was: “We consider your research to be bullsh*t. But on the off chance that it is not, we don’t want you even to send repreints of existing literature to the communists.” Then they asked if they could have the Bulgarian postage stamps from some letters they intercepted, inviting me to chair a session at an international conference in Sofia, on the basis that one of these Men in Black had a son who collected stamps. I refused, rather curtly.
In any case, I am not asserting that I published PART of what made Bostrom famous. I’m asserting, with complete support from edited literature, that I discovered ALL of what he later claimed, and that I left out the more foolish parts of his quasi-religious hand-waving.
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