The constants of nature are among the things you just do not want to mess with - Economist

The constants of nature are among the things you just do not want to mess with

IF YOU give a balloon a modest electric charge—by rubbing it on your jumper, say—you can stick it to the ceiling, thereby both delighting small children and revealing a basic truth about the universe: electromagnetic forces are much stronger than gravitational ones. Despite the fact that there is a whole planet pulling down on that balloon with all the gravity that its six billion trillion tonnes can provide, your party trick is enough to thwart it. This disparity in the forces’ strengths, though, tells you little about why the absolute strengths are what they are. Nor, when it comes down to it, does the hard-won wisdom of the world’s physicists.

The way that the laws of nature, expressed in mathematics, describe the relationships between space, time and matter has a great formal coherence. But some aspects of this systematic and highly successful description stand alone. There are fundamental constants in physics that are apparently arbitrary—numbers that seem to exist entirely in their own right, without reference to the rest of the universe. No obvious reason seems to exist for them to be as they are; they are simply the way the world is.

One of these, called the fine-structure constant, says how strong electromagnetic forces are. Its value is 1/137. If it were larger, balloons would stick more strongly to ceilings. If it were smaller, their weight would more easily pull them down.

Such possibilities might seem to be of no particular importance. It is obvious that the universe would be fundamentally different if either force went away: no electromagnetism, no molecules; no gravity, no planets. That a small change in the strength of either might matter is harder to imagine. But it would.

In the 1950s Sir Fred Hoyle, a British astrophysicist, realised that the abundance of carbon in the universe was a bit of a conundrum. Carbon, like almost all other elements, is made in stars, where fusion creates heavier elements from the nuclei of lighter ones. Nuclei all have positive electric charges, and since like charges repel each other, this means that the nuclear banging together needs to be pretty forceful. If electromagnetism were only a little stronger, then even in the hearts of stars nuclei would not be banged together hard enough to bring forth carbon. That said, if it were just a little weaker, carbon would be simply one step on the way to nuclei that were heavier still, no sooner made than consumed.

• In either case, the result would be a universe radically less amenable to life. The quality and number of the bonds that carbon atoms can form with each other and with atoms of other elements provide a unique versatility when it comes to the creation of large and complex molecules; no other element comes close. Without carbon there would be no polymers with which to make either wool or rubber, no muscles with which to rub the two together, no brains to conceive of doing so—or of explaining what happens afterwards. According to the most recent studies, which take into account far more subtleties than Hoyle knew about in the 1950s, if the fine-structure constant were 4% higher, or 4% smaller, the universe would be essentially rubber-, wool- and carbon-free, and there would be no chemical basis for life.
  This is far from the only example of what is sometimes called “fine tuning” in the physical universe: that is, seemingly arbitrary arrangements which turn out to be necessary for life. The rate at which the universe expands, its ratio of matter to energy and various other apparently arbitrary factors can be seen as showing signs of such fine tuning.
  Some, including some scientists, take this as evidence for the role of an intelligence in the creation of the universe, or the setting of its laws. Hoyle himself had a tendency to such views, though he did not hold them in a way that fitted into any religious tradition. Others see it as a selection effect: of all the universes that there could be, only those in which observers are possible get observed. There should be no surprise to carbon-based life forms in the discovery that their universe is well supplied with carbon; what other sort of universe could they expect?
  This way of thinking has become particularly pertinent as physical theory has opened up the possibility of a “multiverse”—wherein that which is observed, or will ever be observable, from Earth is but the tiniest fraction of all there is, with other universes subject to other rules in an endless panoply beyond. Seen in this light, untuned, un-lived-in universes may not be mere counterfactuals, but real and profuse. Maybe there is something that can be learned by considering them not just as thought experiments, but in the context of the rules that govern what gets created in the whole great ensemble.
  Curiouser and curiouser
  Perhaps the most fruitful way of thinking about fine tuning is to appreciate it as a focus for curiosity. In the 1970s there was talk of fine tuning as an explanation of why, cosmologically speaking, the universe was both smooth and flat (unlike a billiard ball, smooth but not flat, or a shingle beach, flat but not smooth). In the 1980s physicists fascinated by this conundrum came up with a theory that explained both attributes in terms of a single process, known as cosmic inflation, a theoretical path which led, in time, to the interest in multiverses. Perhaps some things which currently appear to be fine-tuned—such as the rate at which the universe’s expansion accelerates—may similarly, with enough hard thought, come to be seen as consequences of a deeper necessity in the laws of nature.
  It is not clear why things which seem fine-tuned should be more likely routes to deeper insights than other aspects of reality. But perhaps they do not need to be. Perhaps a seeming quirk or coincidence that captures the imagination is enough in and of itself to provide the spur to progress. Finding, or appreciating, a way in which the universe appears fine-tuned generates the same sensations as a balloon stuck out-of-reach on the ceiling: delight, curiosity and an exquisite frustration. That is often all the path to understanding needs.
• Economist