More Problems For Sting Theory

In string theory, a paradigm shift could be imminent. In June, a team of string theorists published a conjecture which sounded revolutionary: String theory is said to be fundamentally incompatible with our current understanding of 'dark energy'. A new study has now found out that this conjecture seems to be incompatible with the existence of the Higgs particle.

From Science Daily discussing the following paper:

According to a conjecture recently put forward in [1], the scalar potential V of any consistent theory of quantum gravity satisfies a bound |∇V|/V≥O(1). This forbids de Sitter solutions and supports quintessence models of cosmic acceleration. Here, we point out that in the simplest models incorporating the standard model in addition to quintessence, with the two sectors decoupled as suggested by observations, the proposed bound is violated by 50 orders of magnitude. However, a very specific coupling between quintessence and just the Higgs sector may still be allowed and consistent with the conjecture.

Frederik Denef, Arthur Hebecker, Timm Wrase. "de Sitter swampland conjecture and the Higgs potential." 98 (8) Physical Review D (August 7, 2018). DOI: 10.1103/PhysRevD.98.086004

These papers don't by themselves, entirely rule out string theory, but they do take, what was just a year ago a "landscape" of string theories too vast to sort though, and rule out almost all of those possibilities. 

Some Puerto Ricans Have Berber Ancestry Via The Canary Islands

Maju, after a long silence on genetics issues at his blog, has conducted some very credible independent research that suggests that many Puerto Ricans have some North African Berber ancestry through admixture of that ancestry in the people of the Canary Islands who then migrated to the Caribbean islands about 500 years ago.

The Citation Gap In Physics Publications

Usually, I write about scientific discoveries rather than the scientific process, but today I'll take a moment to look at what is behind the gender gap in physics paper citations.

Sabine Hossenfelder, at her blog, makes a convincing effort to determine why papers by men are cited such much more often than women in physics, as a rebuttal to another investigator who concluded that women are cited less often because they are inferior physicists.

Essentially, almost all of the gap is attributable to women dropping out of active research positions in the profession entirely very early in their careers. This is common among both men and women, but it is more common among women. Among researchers who have published at least five papers, including one in the last three years, there is basically no gender based citation gap. As she explains:

[T]he vast majority of people who use the arXiv publish only one or two papers and are never heard of again. This is in agreement with the well-known fact that the majority of physicists drop out of academic careers.

The first one or two papers of a junior researcher who never publishes again is much less likely to be cited by someone else than a paper published by someone who continues to actively publish for a long time. And, women are much more likely to leave the academic physics profession than men, in part, because many leave to spend time raising children and never return to research physics positions afterwards.