Author: BBC World Service

Cycling is good for our health, good for the planet, and it can be an efficient way of moving around busy cities. But despite all the rational arguments for it, in most cities the number of people who get on their bikes is low.

CrowdScience listener Hans wants to know whether it’s time to change our tactics. Could we persuade more people to cycle if we moved away from focusing on well-intentioned rational arguments and use messages that appeal to our desires and vanity instead? What does the science say? Presenter Caroline Steel is on the case.

She meets Winnie Sambu from World Bicycle Relief to learn about why people in countries like Kenya to choose the bike to get around. She heads out on a ride with psychologist Professor Ian Walker from the University of Swansea to find out what barriers there might be to persuading people to cycle.

She also takes a lesson from one of the world’s top cycling nations as she talks to Marie Kåstrup, a cycling campaigns expert who has advised the Danish government on inspiring cycling and sustaining it in the city of Copenhagen. Also in Denmark, Caroline meets behavioural scientist Dr Pelle Guldborg Hansen who shares his experience in the art of persuasion.

Presenter: Caroline Steel Producer: Tom Bonnett Series Producer: Ben Motley

This week, the Florida Panthers beat the Edmonton Oilers at ice hockey’s Stanley Cup championship, which sent us skating into ice-related science.

First up, we hear about an ancient ice skate that’s been unearthed in Prerov, Czech Republic, which sends us pondering about the physics of ice-skating.

We then discover why licking a flagpole on a chilly day is a bad idea, before delving into the science of cryopreservation.

Next up, we speak to Dr Mark Drinkwater of the European Space Agency, who reveals how satellites can help us monitor and better understand our planet’s melting ice sheets.

Plus, what do you do if you want to play ice hockey but you live near the equator?

All that, plus many more Unexpected Elements. Presenter: Marnie Chesterton, with Chhavi Sachdev and Sandy Ong Producer: Alice Lipscombe-Southwell, with Margaret Sessa Hawkins and Minnie Harrop

How half of the normal matter in the universe is finally confirmed to exist, not that most of us knew it wasn’t. Also, why the next big collider should be muon-muon, and a spider that hangs out around underwater methane seeps.

The universe is thought to consist of 70% Dark Energy, 25% Dark Matter, and just 5% Baryonic matter which is the atoms that make up you and me. At least, that’s what the models suggest. But a well-kept secret between astronomers and cosmologists for all these years has been that they haven’t actually ever seen almost half of that 5% normal matter because it is thinly dispersed as gas between the galaxies and galactic clusters. This week, two studies have been published putting that right.

Satisfactory model-match #1: Liam Connor of Harvard University with colleagues from Caltech have been using a mysterious phenomenon called Fast Radio Bursts (FBRs) to infer what the intergalactic medium is in between, and how much of it there is.

Satisfactory model-match #2: Konstanios Migkas of Leiden University and colleagues have been looking at the very faint x-ray signal from the intergalactic medium, removing the incidental x-ray sources such as black holes, and have managed to identify some structure - in this case a mind-bendingly huge filament of ionised gas stretching between two galactic superclusters - confirming the state of “Warm Hot Intergalactic Medium” (WHIM) as predicted for much of the universe.

Of course, there is not just the cosmological standard model (lambdaCDM) that these satisfy in science today. There is also the remarkably resilient Standard Model of particle physics. A report this week from the US National Academies recommends the US begins building the world’s next particle collider to follow the work of the LHC (and FCC) at Cern. It should, as University of Texas at Knoxville’s Tova Holmes tells us, collide not ordinary, stable, easy to manipulate particles like protons and electrons, but muons.

Finally, Shana Goffredi of Occidental College in California, has found a VERY odd spider. Diving to depths in the submersible Alvin, they have found that a species of small sea-spiders, Sericosura, actually farm bacteria on their exoskeleton. Why? Because they hang around methane seeps on the ocean floor, where a specialist bacteria can metabolize methane – something the spiders themselves can’t do. Not only do the spiders then graze on the bacteria they carry around, they even pass samples of the bacteria onto their offspring by leaving bacterial lunch-boxes in their egg-sacs.

Presenter: Roland Pease Producer: Alex Mansfield, with Sophie Ormiston Production Coordinator: Jasmine Cerys George

Photo Credit: Jack Madden, IllustrisTNG, Ralf Konietzka, Liam Connor/CfA