No Small Matter

Is theoretical physics stuck? And should you worry?

Kenneth Silber from the March 2007 issue

(Page 2 of 2)

String theory, as normally formulated, is "background-dependent," treating space and time as an unchanging stage (albeit a rather exotic one-the theory requires multiple dimensions, which are assumed to be unseen because they are too small). This means, according to Smolin, that string theory falls short as a foundation for general relativity and relies too much on assuming, rather than explaining, the nature of space and time.

Smolin surveys various background-independent alternatives to string theory. Some of these involve dissolving space and time into cause-and-effect relations among events, or using geometry that is equivalent to A times B not equaling B times A. Loop quantum gravity, an approach in which Smolin has been a key figure, recasts space and time in terms of field lines similar to those one might use to diagram a magnetic field; these lines can become loops if there is no matter present. Ultimately, Smolin ventures, progress will be made by "unfreezing" time-thinking of it as something more dynamic than physicists thus far have contemplated.

The Trouble With Physics criticizes not just string theory but string theorists. This community numbers more than 1,000 researchers worldwide, compared to a couple hundred focused on loop quantum gravity and other alternatives. Smolin portrays string theorists as tending toward arrogance, insularity, and groupthink; they value technical ability over original thought, follow faddishly the ideas of a few top physicists, and look down on adherents of other theories. This culture, in Smolin's telling, eschews the philosophical bent of Einstein and quantum theory's founders, preferring the "shut up and calculate" attitude of later particle physicists. That latter approach, Smolin suggests, was valuable when new experimental data abounded in the 1960s and '70s but is far less productive now that theory has run ahead of experiment.

Smolin's negative description of string theory's practitioners is probably overblown. Some of their writings, such as Brian Greene's The Fabric of the Cosmos, evince considerable philosophical interest in space, time, and matter. Nonetheless, Smolin is right that science needs both "craftspeople" and "seers," the former focused on technical problems, the latter on deeper meanings and new ideas. He makes a plausible argument that physics institutions have become too geared toward producing crafts­people rather than seers. The way for young physicists to get jobs, tenure, and grants, he notes, is to fill in the details of research lines established by their elders.

One reason for this, as Smolin points out, is that universities are no longer growing as fast as they did for decades after World War II, so there is more competition for physics posts and less room for nonconformists. Furthermore, theoretical physicists rely heavily on financial support from just a handful of federal agencies, with some private foundation money thrown into the mix. These limited funding options provide further incentives for conventional thinking. Observing that such incentives are not limited to physics, Smolin warns that intellectual sclerosis could be developing throughout the sciences.

Against all this, Smolin advocates that scientists embrace an ethos of multiple approaches to open questions, avoiding consensus until evidence is decisive. He also calls on administrators and grant officers to promote such diversity. This seems too limited a solution to fix the problems he identifies. Probably what is needed is greater institutional diversity, with more and different organizations involved in theoretical physics. Smolin's employer, the Perimeter Institute, is a step in that direction, avoiding academic hierarchies and drawing on varied public and private support, including donations from individuals and companies. Perhaps the private sector will develop a broader role in supporting theoretical physics, financing quantum gravity research and the like for prestige, tax breaks, or the chance of some future tech breakthrough.

Although Smolin does not thoroughly explore the possible solutions to the problems he cites, The Trouble With Physics is ultimately an optimistic book. If the recent difficulties of theoretical physics arose from flaws in scientific culture and institutions, rather than from the sheer abstruseness of natural laws, our progress in understanding the universe just might resume.

Kenneth Silber is a science writer and editor based in New York City.

Comments

|10.12.10 @ 9:50AM|#

this is an excellent review.but it should be noted that Smolin does not appear to realize that theoretical physics is thriving in areas outside of quantum mechanics and cosmology. Specifically, the area of condensed matter (or soft matter as it is called by the 1991 Nobel Prize winner, P.-G. De Gennes). but TCM physics is often practiced out in non-physics departments such as Materials Science.

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nfl jerseys|11.6.10 @ 3:14AM|#

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Ken Silber|2.23.11 @ 2:17PM|#

In fact, there may be a stupendous number of universe types compatible with the theory-about 10500 by one estimate.

That should be 10^500 (10 to the 500th power).

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