July 23: Best of Quirks & Quarks - Holiday listener question show
Where does the rubber from tires go? Can a laser cut through a mirror? Why don’t some animals vomit?
This episode originally aired January 1, 2022
It's a Quirks & Quarks tradition - our ever-popular Listener Question Show, where we find the experts to answer your questions.
Anthony Peterson from Peterborough, Ontario asks: How close would you have to be to the source of gravitational waves to physically notice them or for them to do damage?
Jess McIver, the Canada Research Chair in Gravitational Wave Astrophysics and assistant professor of physics and astronomy at University of British Columbia, says gravitational waves created by some of the most energetic events in our universe create tiny ripples in the fabric of spacetime. The first gravitational waves detected in 2015 from a pair of colliding black holes produced ripples so tiny that by the time they reached Earth, only distorted spacetime by a fraction of the size of a proton. If our planet was close enough to the colliding black holes for their gravitational waves to theoretically do damage, ripples in spacetime would be the least of our worries.
Ivan Christensen in Mahone Bay, Nova Scotia asks: Where does the rubber from tires go?
Markus Brinkmann, an assistant professor in the Toxicology Centre in the school of environment and sustainability at the University of Saskatchewan, says tire rubber that gets worn down ends up as tiny dust-sized rubber particles at the side of the road that eventually ends up in our storm drainage system. In Saskatoon, he found the rubber particles either drained directly into the river or into a storm pond where they settle in the soil before the water is released back to the river. This is a concern, especially due to another study that showed how a certain chemical in the tires can transform to become toxic to Coho salmon.
Loretta in Ladysmith, British Columbia asks:Most humans have a dominant side, for example right handed or left handed. I don't see this trait in animals. Why have humans evolved with this trait?
Dr. Jed Meltzer, a Canada Research Chair in Interventional Cognitive Neuroscience at the Baycrest Centre and University of Toronto says that why handedness evolved is not entirely clear. However, it is thought that as humans became more adept with tools, the associated fine motor skills might have favoured the development of a dominant hand. Lateralization, as handedness is technically known, is found in other animals, including primates, which tend to show a preference for right handedness, although this tendency is not as extreme as in humans.
Susan Forest of Calgary, Alberta asks: What is the evolutionary advantage of menopause? Do symptoms such as waking regularly at night give us an advantage, such as more nighttime alertness protection for the group?
We turned to Dr. Jen Gunter, a Canadian OBGYN and author of The Menopause Manifesto. She explained that while menopausal symptoms don't give us any advantage, menopause itself is an advantage because of something called the "grandmother hypothesis." Essentially, women continue living long after their reproductive years so that they can help with their grandchildren.
Joan in Vernon, British Columbia asks: My ten year old grandson, Finley Daniel, learned in school recently that four animals don't, or can't vomit. These are rabbits, mice, rats and horses. Why is that?
Dr. Luis Arroyo, an Associate Professor at the Ontario Veterinary College at the University of Guelph, says you can add all other rodents to that list. The diaphragms of rodents are weak, and their stomachs have evolved in a way that does not allow the contents to easily move up through the esophagus. They compensate for the inability to vomit by having a strong sense of smell and taste. This makes them picky eaters, and careful not to ingest anything that will make them feel sick.
Several listeners, including Karl Simmons of Vancouver, were curious about the environmental impact of space flight, and space tourism in particular.
Aaron Boley, associate professor and Canada Research Chair in Planetary Astronomy at the University of British Columbia says that the concern with space tourism is when it ramps up to thousands of flights per year. The issue is not just C02 emissions, but also that rockets generate soot in the form of black carbon, as well as water vapor, and will be depositing that into the upper atmosphere. By adding pollution up there, it could help deplete the ozone layer, produce stratospheric clouds, and contribute to climate change.
Geoffrey Sperber from Edmonton, Alberta asks: Why do mammals have a body temperature of approximately 36 degrees Celsius?
Danielle Levesque — a Canadian assistant professor of mammalogy and mammalian health at the University of Maine says — says that mammals' normal body temperature ranges from 30 C to 41 C so they can get up and go at a moment's notice in whatever environment they're in. Outside of that range, mammalian proteins and enzymes either don't function or they unfold and become permanently damaged. Mammals generate their constant source of heat thanks to their leaky mitochondria that power their cells.
Dan Burgess from Chateau Richer, Quebec asks: If a mirror reflects light, a laser shouldn't be able to cut through it, no matter how strong it is. Can a laser cut through a mirror? If so, why?
Heide Ibrahim, a research scientist at the Advanced Laser Light Source Laboratory of the Institut National de la Recherche Scientifique in Varennes, Quebec says this is a function of the power and intensity of the laser beam. Mirrors or shiny metal surfaces will reflect laser light up to a threshold of intensity, which can be achieved by focusing laser beams on a small area.
Wendy in 100 Mile House, British Columbia asks: Is scrapping an old gasoline-powered car and replacing it with a new electric one always better for the environment?
Daniel Posen, an assistant professor in civil and mineral engineering at the University of Toronto, says that it depends what kind of driving you do, what specific models of car you are comparing, where you are located, and which environmental impacts you're worried about. But fundamentally, when comparing the average gasoline car to the average electric car for the average driver: an electric car comes out on top.
Judith in Ottawa asks: I wonder why, if our bodies completely change all their cells over a period of time, we retain scars. Shouldn't scars disappear as new cells replace damaged ones?
Dr. Peter Vignjevic, a dermatologist and an assistant clinical professor in the faculty of health sciences at McMaster University in Hamilton, Ontario says we do replace all cells over a period of about 28 days, but this only happens in the top layer of skin called the epidermis. This process doesn't happen in the second layer of skin, called the dermis, or any deeper layer. If a cut is deep enough to penetrate the dermis, the cells that form hair follicles and sweat glands found in that layer, are no longer viable. The result is the formation of scar tissue.