By: Nathaniel Tok

SFU physics study questions cosmological constant

SFU physicist Levon Pogosian has shown that dark energy might not be considered the cosmological constant through an international study on dark energy that he co-led. Dark energy is the energy of empty space that makes up most of the universe.

The study, published in Nature Astronomy, documents data collected by the researchers as they studied dark energy density over time. Before this study, it was believed that dark energy did not change. However, the study’s results suggest that dark energy density might have increased over time. This finding runs contrary to the prevailing hypothesis, which is based on Einstein’s idea that the universe and the cosmological constant are constant, that density should decrease as the universe expanded. The study also suggests that dark energy’s repulsive gravity is responsible for accelerating the universe’s expansion.

“What we find is not conclusive evidence,” emphasized Pogosian. “We see that the data prefers dark energy if it was changing, but the preference is not sufficiently strong to rule out a cosmological constant.”

The researchers await results from the Dark Energy Spectroscopic Instrument Survey starting in 2018, in the hope that it will confirm their findings.


Mothers and fathers differ in ‘baby talk’

According to SFU psychology professor Tanya Broesch, mothers and fathers in urban and Western societies have different ways of talking to babies using ‘baby talk.’

Mothers altered the pitch of their voice when talking to babies, which was a common trait across cultures. Canadian fathers however, did not raise their pitch but slowed down their speech rate when practicing baby talk.

This research was the first of its kind to look at how parents alter their voices when talking to babies. It was conducted as part of numerous studies through which Broesch is investigating how early experiences affect development. Broesch commented on the significance of the data collected, saying, “Evidence for this suggests that this parenting behavior may be universal — something that is common across diverse societies.”

Another study showed that fathers from the non-Western South Pacific society of Vanuatu modified their pitch in a similar manner as mothers in Western societies. Broesch added that this evidence could demonstrate how similar communicative problems are solved with variations in behaviour across different cultures.

Broesch is currently finishing two follow-up studies with SFU linguistics researchers.