Tuesday, April 6, 2010

Guest Week: The Curious Right-ness of the Universe

Today’s Guest-Poster is long-time reader and commenter Kevin Vigor. Kevin is the only Guest-Poster I haven’t met in real life. But from comments and email correspondence, I feel that I know him reasonably well. Specifically, this is what I know. Like me, he is a cyclist, rationalist and non-native Utahn who lives in Salt Lake City (our children attend the same school) and works in the IT industry. Unlike me, Kevin originates from Gondwanaland. I’m pretty sure he told me once he’s from South Africa. I could be mistaken, but in any event I’m pretty certain it’s one of those Southern hemisphere countries where people talk funny and routinely fight off large reptiles with garden implements.

I mention this because it explains the spelling errors discrepancies peppered throughout his post- favour”, “behaviour”, “fibre”, etc., which I fought off my American spell-checker to leave intact (and which should no doubt please Fellow Funny-Speller P65.)

Kevin’s got a great and timely post. A couple weeks back, when posting about Mars, I mentioned how hard it was for me to get my head around the idea of an entire planet where nothing ever happens. In this post, Kevin takes up that mind-bender at a whole other level: why life- or most anything at all- happens in the universe as a whole. The post isn’t technical, but it does require a bit of focus and attention to follow along, so maybe have a cup of coffee first, answer those couple of urgent work-emails, close your office door, look busy* and dive in.

*I always wear my phone headset when reading good posts, so co-workers will think I’m on the phone.

It also happens to contain probably the brainiest Nested Tangents yet in the history of this blog.

The Post

The universe appears, at first glance, to be a rather inhospitable place. It's mostly empty, bleak and dark, and the few not-empty bits are mostly extremely hot balls of exploding gas, massive unstoppable black holes devouring less fortunate objects, or sad, desolate rocks waiting their turn in the black hole. So it would be easy to conclude that life, clinging precariously to a small blue rock circling a rather undistinguished star, is an astonishing thing, a triumph over unspeakable odds, an inexplicable fly in the dismal broth of infinity.

But it turns out that quite the opposite is true. The universe has stacked the deck in our favour. And not just a little - the game is rigged to an astonishing degree. According to the standard model of physics* the universe has about twenty initial parameters. These are things like the mass of a neutron, the charge on an electron, and so forth. These are the values which determine the behaviour of the cosmos. As far as we know, they were set at the beginning of time and are completely arbitrary. Why aren't electrons the size of baseballs? Well, we don't know of any reason. Nor do we know why they are the size they are. We simply have to measure and observe these parameters. But when we do that, we come to a startling discovery: these initial parameters are very precisely tuned to result in the complex, structured universe that is necessary for life. Even tiny deviations in any of these parameters would lead to conditions where we, or life as we can envision it**, could not exist.

*I love this name; I envision a worn-down universe salesman wearily trying to sell add-ons to the suave and dapper creator: how about the moon roof? Nope, says the creator, picking lint from his lapel, just the standard model. C'mon, buddy, how about the power ashtrays? Nope, just the standard model.

**In a paper regarding the possibility of false vacuum collapse, which would result in an instant reshuffling of those initial parameters of the universe, we find this lovely quote: "...in the new vacuum there are new constants of nature; after vacuum decay, not only is life as we know it impossible, so is chemistry as we know it. However, one could always draw stoic comfort from the possibility that perhaps in the course of time the new vacuum would sustain, if not life as we know it, at least some structures capable of knowing joy. This possibility has now been eliminated."

For instance, consider the 'alpha' parameter (also known by the far more mellifluous name 'fine structure constant'). Alpha describes (in some manner far beyond the understanding of your humble author) the strength of the electromagnetic field, i.e. the force exerted between charged particles like protons and electrons. It is a dimensionless constant; like pi, no matter what units of measurement you use, the value is identical.

Tangent: I find the idea of dimensionless universal constants like alpha and pi fascinating. It wobbles the mind to realize that any intelligent life anywhere in the universe knows the value of pi and would recognize it if we presented it to them. It's quite literally universal truth.

Nested Tangent: It is interesting to contemplate how one would go about presenting the value of pi to an alien intelligence, presumably as a demonstration of our own intelligence. It's easy enough to communicate integers; assuming we had a simple on-off blinking mechanism like a light we can simply transmit bursts of flashes separated in time. But pi, being irrational, is harder to communicate. '3' isn't exactly precise enough to get the job done and I cannot think of any way to communicate irrational numbers over such a limited channel without introducing the concept of the numeric base. As I'm sure you know, dear reader, we are accustomed to using base ten in our daily counting needs, but there is no reason to suppose an alien would use such a system. So first we would have to communicate the base we are using. Having thought about this a bit, I came up with the following scheme: transmit the prime number sequence, which again should be universally recognizable, using a longer interval to separate the values and a shorter interval to separate the digits in each base-ten number. So, with space representing the long interval and dash the short, we would transmit: * ** *** ***** ******* *-* *-*** (1, 2, 3, 5, 7, 11, 13...). This should unambiguously establish the fact that we are using base ten. With that established one could then begin transmitting the digits of pi in base ten (*** * **** * *****....) with some certainty of being understood. OK, perhaps that was interesting only to me, but if you can think of a better or more universal way to communicate irrational numbers to aliens I'd be delighted to hear it.

Of course, we know many ways to derive the value of pi (including the incredibly freaky BBP Algorithm, which lets you calculate any digit of pi without calculating the preceding digits - think on that a moment!) and we cannot envision a reality in which the ratio of a circle's diameter to its circumference is any different. Unfortunately, we have no idea how to calculate alpha, but can only measure it, and can easily envision universes in which it had a value different than the approximately 1/137* that it is in ours.

*Richard Feynman, the most entertaining physicist ever, had this to say about alpha: "It's one of the greatest damn mysteries of physics: a magic number that comes to us with no understanding by man. You might say the "hand of God" wrote that number, and we don't know how He pushed his pencil." He wasn't the only one fascinated by the number, either; Sir Arthur Eddington, a preeminent astrophysicist at the turn of the 20th century, constructed long numerological arguments to "prove" that alpha was exactly 1/136. When experiment revealed the actual value was close to 1/137 he hastily reformulated his arguments to "prove" it was precisely 1/137. Alas, truth refused to be quite so neat.

So - what would a universe with a different fine structure constant look like? To understand at least one ramification of this, we must consider the structure of an atomic nucleus. In the nucleus of anything more massive than hydrogen there is a desperate struggle of forces: the positively charged protons repel each via the electromagnetic force, while the strong nuclear force tries to hold them together. So if alpha, which indicates the strength of the electromagnetic field, were larger, the protons would repel each other more strongly, and in the absence of a corresponding increase in the strong nuclear force (another of those pesky initial universe parameters) the atomic nuclei become more unstable. In our universe, elements with up to about 92 protons in the nucleus (uranium) are reasonable stable; but with only a very small increase in alpha no element except hydrogen can exist for any length of time.

So even small increases in the value of alpha spell disaster for life, unless you fancy the idea of trying to assemble sentience armed only with varying densities of hydrogen.

What then, you might ask, if alpha were to have a lesser value?
It probably won't surprise you that the answer to that is disaster also, though of a more subtle form. One must consider that the electromagnetic force has another enemy: gravity. Stars burn because gravity becomes strong enough to overcome the electromagnetic repulsion between hydrogen nuclei, fusing them together into helium (and by happy coincidence releasing an enormous amount of energy in the process). So if alpha were less, gravity would be relatively stronger, and smaller bodies would burst into flame, their puny electromagnetic resistance crushed under the iron heel of gravity. One doesn't have to dial alpha down very much before Earth-sized bodies start igniting, which makes things hard on the inhabitants. Worse, the lifetime of the resulting tiny stars is dramatically shorter than the stars we know, curtailing the time available for life to evolve. In short, the resultant universe isn't very conducive to the creation of pizza, carbon fibre bikes, and all the other things we take as requirements of sentient life*.

*There are numerous other subtle and awful effects of dialing down alpha: "Just Six Numbers" by Martin Rees does a fantastic job of explaining just what a bad idea that would be, in case you were inclined to give it a try.

So it turns out alpha is very nicely tuned to support just the kind of universe we need, one with lots of stable elements and stars which burn long enough for us to evolve.

And it turns out that the rest of those twenty-odd initial parameters I mentioned before? Yeah, same story all over. Even the most tiny of tweaks to something like electron mass is pure ruination. This universe looks an awful lot like it was set up at the very beginning just exactly for us.

The first guy to comment on this was an American physicist by the name of Robert Dicke, who pointed out what came to be known as "Dicke's Coincidence"* in the 1950s. But the first guys I know of who really ran with the idea were John Barrow and Frank Tipler, in their 1986 book, "The Anthropic Cosmological Principle". It's well worth reading (though be warned that while most of it is layman friendly there are passages of heavy math that left me bewildered) - they devote an amazing amount of effort to demonstrating just how fine-tuned the universe is to support our existence, and to my knowledge those conclusions have held up well, in the sense that most cosmologists agree (though of course, there are still some who differ**). After demonstrating at considerable length the unlikelihood of our cosmos, they then turn their attention to the obvious question: Why do we find ourselves in such an unlikely place? Here, things get a lot more contentious.

*insert puerile snigger here.

**Barrow and Tipler base many of their arguments on the processes that lead to formation of carbon, which is certainly essential for life as we know it, and which is indeed very sensitive to the initial conditions of the universe, but some contrarians accuse them of 'carbon chauvinism' and suggest other forms of life might arise in differently tuned universes.

Barrow and Tipler offer three variants of the 'anthropic principle'. The Weak Anthropic Principle is really a simple little tautology of the sort a fifth grader might find clever: if the universe *weren't* tuned to support life, we wouldn't be here to observe it; therefore, we should not be surprised to see it, no matter how unlikely it might be. It's certainly a difficult argument to refute, but it is very unsatisfying. Further, it requires either a massive and unlikely (Dicke's) coincidence* to explain how the one and only universe just happened to be so awesome, or else that there be a very large number, perhaps an infinity, of different universes with different parameters. Some credible cosmologists (like Martin Rees) posit this latter theory, commonly referred to as the multiverse theory. They suggest that the vast majority of many, many parallel universes are lifeless, sterile places, but that the sheer number of them explains the coincidence of ours. Such people thus find the Weak Anthropic Principle sufficient. But not Barrow and Tipler**. They keep on going to our next stop, the Strong Anthropic Principle.

*More puerile sniggering.

**Nor, for that matter, do I. While I am hardly qualified to have a real opinion on the subject, invoking the enormous elaboration of an infinity of parallel universes just so we can have ours seems such a shockingly inelegant, brute force solution that I can hardly bear to contemplate it. I prefer my cosmology with just a tad more grace, thanks all the same.

The Strong Anthropic Principle states that a universe, any universe, *must* at some point contain life. Proponents of this position usually point to quantum mechanics, where observers play a special, magic, spooky role. Schrodinger's cat is both alive, and dead, and neither, until someone looks in the box. And observers, we assume, must be alive, and probably sentient at that. So we know that the mere presence of life alters the behaviour of reality in a very deep and very non-obvious way. It is possible, then, that the universe cannot function properly without observers, and so therefore that it must produce us, or not exist at all.

This argument is quite compelling, but it has its flaws. First, it is not universally accepted that observers really do have such a magic privileged role in reality. Heisenburg's interpretation of quantum mechanics (usually wrongly called the Copenhagen interpretation) grants us this exalted status, but there are many other interpretations, some of which do not. Second, and perhaps more seriously, it simply defers the question. Sure, a universe cannot exist without us - but how did it manage to come to be? We should not be surprised to find ourselves in a universe well suited to ourselves, the Strong Anthropic Principle says, but feel free to continue to be astonished that a universe exists at all.
This turns out to be insufficient to satisfy Barrow and Tipler, so they press on, arriving at what they term the Final Anthropic Principle. Which is, in a word, creationism. They spend a lot of time dancing around it, but in they end, they strongly suggest that the existence of our unlikely universe is evidence of an intelligent creator (others following in their path are less reticent).
Well. That's a damn unsatisfying result. What a long way we've come, how carefully we've studied and observed and measured and reasoned, only to defer explanation to a magic fairy? The whole thing feels like cheating. It's worse than an M. Night Shyamalan movie*.

*Spoiler - it's the trees!

But what's the counter argument? What, other than some intelligent creator, can possibly explain the beautiful, delicate balance of a universe where carbon and oxygen not only exist, they come together in the form of J boats and whiskey and Angela Gossow and other exquisite delights?

Well, Lee Smolin is glad you asked. In his 1997 book, The Life of the Cosmos, Mr. Smolin suggests a wonderful, elegant alternative. The book is in many ways horrible - Mr. Smolin is not a terribly gifted author, often didactic, and the book feels like several unrelated pieces awkwardly jammed together, some of which were written for an audience far smarter than I ("now, as you recall from your exhaustive knowledge of gauge theory..."). But despite that I cannot recommend it enough, purely for the sheer wonder of the central idea. It's so lovely and so novel that I feel bad giving it away here. But just to give you a hint...

[SPOILER ALERT]

Smolin's central idea is that the constants of nature evolved by a process of natural selection. Just as natural selection in biology led to the beautiful and wildly diverse life we find about ourselves, so did a process of cosmological natural selection lead to our bizarre and wonderful universe. I cannot possibly do the argument justice here - it involves universes spawning though black holes and every time I try to explain it it sounds completely unbelievable. But then so does the germ theory of disease - you mean there are little living things that are too small to see? And they're everywhere? And if they get in me, they make my nose run? Dude, are you even trying to be reasonable here? Trust me, Smolin does a better job of making the idea plausible. Compelling, even.

So, if Alex is fool enough to publish this, and I've managed to pique your interest in the rather insignificant matter of why the hell we're here, get to the library and grab a copy of Smolin's book. It's an adventure for your mind, a triumph of rationalism, and with the weather apparently determined to keep us indoors the next week or so, you'll have the time on your hands.

12 comments:

Ski Bike Junkie said...

And to think I was satisfied with the weak anthropic principle.

KanyonKris said...

Excellent post, Kevin. And timely since I've been on a physics kick lately (relativity, quantum mechanics, standard model). I considered writing a guest post on what I currently understand of the standard model, but I doubted my ability to make it coherent and interesting. But you've done a marvelous job summarizing many of the topics I've been thinking about lately.

I see that my local library (yes, Orem, Utah) has a copy of Smolin's book - I'll get it soon.

Just the idea of evolutionary creation (can I use those two words together? I see evolution as a creative force) of the universe is attractive and seems reasonable. However, a creating architect also seems reasonable.

Why do we even ask these questions? OK I'll stop, the rabbit hole is deep enough with the topics of this post.

Kevin, I do feel silly that I've struggled to find good physics books and never thought to ask you. Singh's "Big Bang" was a good intro. "Quantum Zoo" had a few good analogies, but didn't go deep enough. "Particle or Wave" helped me understand a few tricky concepts, but the opaque sciency writing gets in the way. I've had Feynman's book on QED on my list. Any books you'd recommend?

BTW, you should be pleased to know your idea of transmitting primes was also favored by Sagan in his book "Contact" (or watch the movie which stays pretty true to the book).

Of course the best way to communicate pi is visually. Show a picture of a circle with a bisecting line for the diameter and they should know what you're talking about.

Enel said...

AWESOME POST!

I greatly enjoyed that.

Front the title, I thought you were going to address the chirality of certain molecules (proteins). Why is everything right handed?

Great explanation of stuff I have sort of known, but not well enough to teach as you did.

Enel said...

Forgot: I loved the descriptions of earths bursting into fusion.

This is the first academic and rationalistic look I have seen on the Anthropic Principle. Nice to see serious thinkers taking it seriously.

@Skibike: to think I was satisfied with a creator.

Kevin Vigor said...

Kris: fwiw, I think the idea of 'evolutionary creation' is perfectly reasonable; if one were to create a universe, I'm sure you'd want some tools to help you out, and evolution seems like a darn handy one.

As to books, it's tricky finding ones that have enough detail to be challenging but not so much as to be overwhelming. There's _Brief History of Time_, of course. There's _Seven Mysteries of Life_, which isn't really physics but is fantastic (Alex recommended it initially and I second heartily).

I got a lot of mileage out of _In Search of Schrödinger's Cat_ by John Gribbin for an approachable intro to quantum mechanics (and from poking at amazon, I see there's now a sequel, which I will have to read); but I suspect _Quantum Zoo_ covers much the same ground, though I haven't read it.

Nor have I read QED, but anything Feynman is worth reading.

Right now I'm working on Smolin's _Three Roads to Quantum Gravity_ which is rough going so far (meets the 'challenging' requirement for sure!); next on deck is _The Emergence of Everything: How the World Became Complex_ which I've had recommended. I'll let you know how it goes.

Anonymous said...

Very interesting post. Still trying to wrap my feeble mind around your concepts.

Just caught the end of a show tonight called "Parallel Universe" on the Science channel (missed the first half of it so I may not understand it very accurately). Apparently, three scientists recently came out with a new theory on big bang. Let me sum up, there's an 11th dimension with lots of alternative/parallel universes and when two of them collided, it resulted in the "big bang". It is their theory that these big bangs happen frequently when universes collide, creating alternate universes.

I may not be explaining accurately but it is something like that. In other words, what existed/happened before the big bang is not some mystery that can never be explained but a mere continuation of all the parallel universes. Pretty amazing that these scientists came up with this theory that explains so much on an hour train ride on the way to a theater production.

Thanks for being a guest poster but you are making my head hurt!

mtb w

Chicken Legs said...

That one made me feel stupid! Is my stupidity being observed by sentient beings?

Ski Bike Junkie said...

Enel: not saying I don't believe in a creator. It's a question that can't be answered for certain based on the available evidence. The weak anthropic principle is sufficient cause for doubt that all other explanations, no matter how well-formed, are speculative. We can speculate all we want with additional, more ellaborate anthropic principles or creator/creation stories, but that doesn't make them more true.

Enel said...

I agree with you, but is not belief in the weak anthropic principle itself speculative?

Perhaps I don't understand it (or you) properly.

My point (I think) is that all the above cosmologies are speculative, whether they include a creator or not.

Ski Bike Junkie said...

Enel: if life exists anywhere in the universe, it certainly exists here. That much is certain. If it only occurred once (speculative), it occurred here (certain). I can't find any basis for disagreeing with this part.

My point is that this aspect of the weak anthropic principle is enough to eliminate certainty in any other explanation about where life came from and how. So yes, I think we agree that it's all speculative.

I don't think our respective positions as to which speculation is most likely are aligned, but that's as much because I don't really have an opinion in that regard as anything else.

KristenT said...

Wow, that was a great post! I always struggled with physics in college, maybe I just didn't have the right kind of teacher.

Jube said...

Kevin, Way to bring in lots of different ideas about the origin of the universe, or is it multiverse? Really deep stuff that will keep me thinking for a while.