Saturday, June 27, 2015

Converging To Nothing

Physics World magazine’s blog is one of my regular stops. This week they’ve been reporting on the Convergence conference held at the Perimeter Institute for Particle Physics in Waterloo, Ontario, Canada, June 20-24

Here are some quotes from Physics World’s
interview with Neil Turok, the Institute’s director.

Turok explains that the “large bandwagon” of the last 30 years has not found experimental support. The bandwagon in question is the Standard Model of particle physics established in the 1970s, which, he says, people have been elaborating ever since. “Grand unified theories, supersymmetry, string theory, M-theory, multiverse theory,” he lists. “Each is not particularly radical, but is becoming ever more complex and arbitrary.”

To illustrate the lack of experimental support for these ideas, Turok describes how many people were hoping string theory would represent a radical development; but since string theory – as currently interpreted – leads to the multiverse, Turok describes it as the “least predictive theory ever”.

Indeed, experimental support has not been found for other extensions of the Standard Model either. “We have discovered the Higgs and nothing else,” says Turok, “yet the vast majority of theorists had been confidently predicting WIMPS (weakly interacting massive particles) and supersymmetric particles…Theorists are walking around in a bit of a stunned silence.” He adds that it could turn out to be right that all sorts of other particles are needed along with the Higgs – but that thought seems to be misguided.

“My view is that this has been a kind of catastrophe – we’ve lost our way,” he says. “What we need are ideas as simple and radical as in the start of the 20th century with quantum mechanics.”

So what might these ideas look like? Turok explains how observations have shown that the universe is simpler than we ever expected – in contrast to our theories, which are becoming ever more complex. For example, Planck has mapped the CMB (cosmic microwave background) sky and we have found that only two numbers are needed to describe it. The hydrogen atom is another example of something that can be described with a simple model – only three numbers are required.

“Yet theories about multiverses, et cetera, have all kinds of parameters,” says Turok. “The theories are just way more complicated than the phenomena.”

So what will Convergence do differently? First, it will bring together all fields that are giving interesting clues, including experiment and theory. Second, invitees are strongly encouraged to come with an open mind. “Convergence,” says Turok, “aims to bring theorists and experimentalists together in humility – acknowledging that other methods haven’t panned out. We need to say in an honest way where we’re stuck.”
That sounded good, so I followed the conference blog for a summary of what was happening. Despite the high expectations for the conference, apparently nothing new surfaced there. The final post, summarizing the closing panel, stated that the same underlying questions motivated everyone: “What are we missing? What puzzles remain?” This was taken in a positive way, meaning that everyone had the right attitude. However, I first heard these questions with negative connotations eleven years ago, as I reported here. Physicists had no answers then, and they still have none.

The word “exciting” and its variations appear eight times in the two-page closing panel summary. Everybody agreed that the questions, of which there are plenty, are more exciting than answers, of which there are none, in spite of the fact that some of the questions have gone unanswered for decades. That sounds more depressing than exciting to me. Still, Physics World reports that most of the participants thought the conference was a success, allowing researchers from different branches of physics to meet and share ideas.
Those folks could find many of the answers in this blog, of course. However, the last person a physicist wants to hear from is a retired electrical engineer, as I reported in the very first post of this blog, almost exactly one year ago.