July 18, 2020 — The Quirks & Quarks listener question show
You ask us your burning science questions. We find you answers.
Originally published on Jan. 4, 2020.
Debra Pereira from Vancouver asks on behalf of her 3½-year-old child: "Why are dinosaurs big and we're small?"
Victoria Arbour, the Curator of Paleontology at the Royal BC Museum in Victoria, explains that there are a couple of reasons that some dinosaurs became so big. One is simply an evolutionary arms race between plant-eaters and carnivores. But another explanation for their size is that because of a body structure that was less consistently dense than modern mammals, dinosaurs were big for their mass.
Bent Nielsen from Calgary asks: "European people from northern countries and some northern dogs like Huskies have blue eyes. Are there benefits to having blue eyes in the north?"
According to Ryan Gregory, Professor and Chair of the Department of Integrative Biology at the University of Guelph, there's no clear answer to this question. It's possible that blue eyes in humans might bring small advantages for making Vitamin D, allowing better vision under low light, or helping individuals to better cope with seasonal affective disorder. They also might have been selected for as an attractive trait among some Eurasian populations.
In dogs like huskies, blue eyes are likely a trait selected by breeders for their interesting appearance.
Rennie Moffat from the Greater Toronto Area asks: "In the winter, the lights of the city skyline appear more clear and crisp. Am I imagining this or is cold air visually sharper?"
Some of the clearest views of the night sky happen on the coldest nights of the year, largely because cold air doesn't hold moisture as well as hot air according to Ilana Macdonald from the Department of Astronomy and Astrophysics at the University of Toronto. Water vapour in the atmosphere scatters light, which can make your view of a skyline — or the stars — a little fuzzy.
Marcia Porter from St. John's, Newfoundland and Labrador, asks: "Where are the minerals used in electric vehicle batteries mined?"
Elena Baranova, a Professor in the Department of Chemical and Biological Engineering at the University of Ottawa, explains that modern electric vehicles use lithium-ion rechargeable batteries. The most common elements in this type of battery are lithium, cobalt and graphite. Most of the world's lithium is mined in Argentina, Chile and Bolivia. Graphite is mined in many places including Canada. Cobalt is mostly mined in the Democratic Republic of Congo, a practice that's been criticized for environmental damage and human rights abuses. Partly because of this new battery chemistries that use less cobalt and more nickel and manganese are becoming more common.
John Brennand from Maple Ridge, B.C., encountered 14 ant nests about 3 metres apart on a recent walk in his neighbourhood. He asks: "Are they all individual, distinct nests, or could they all be part of the same nest but with many entrances?"
Aaron Fairweather, a PhD candidate in Environmental Sciences at the University of Guelph, says that of the 932 species of ants in BC, these are likely one of the species that make small nests, and so are individual colonies with a single queen. Some ant species make much larger colonies with multiple queens, which can be much larger. In extreme cases single colonies of species like the Argentinian ant can cover kilometres, but these ants don't occur in BC.
Kelly Stowell from Windsor, Ont., asks: "It's my understanding that because the universe is expanding, galaxies are moving away from each other. If that's the case, then why is our galaxy and the Andromeda galaxy on a collision course with each other?"
This is actually not a contradiction, according to Will Percival, Professor and Distinguished Research Chair in the Department of Physics and Astronomy at the University of Waterloo. On a large scale the universe is indeed expanding with distant galaxies and clusters of galaxies moving away from each other. But on a local scale, some galaxies can be near enough to each other for gravity to dominate and so can be drawn toward each other.
Michele Rodger from Terrace, B.C., asks: "Is plastic made from corn or hemp, for example, any better for the environment?"
Love-Ese Chile, a bioplastics researcher and consultant with Grey To Green Sustainable Solutions in Vancouver, says that bioplastic can be better for the environment than conventional non-biodegradeable plastic, which can take up to 10,000 years to decompose in landfills. However this is only the case if bioplastics are designed to biodegrade and only if they end up in the conditions that will facilitate breakdown, such as industrial compost facilities. If biodegradeable plastic ends up in the soil or in the oceans, it won't break down very quickly and will persist for a much longer period of time.
Wendell Ward from Lanark, Ontario asks: "Water at the top of Niagara Falls has potential energy. As the water drops from the falls, the potential energy becomes kinetic energy. When the water lands in the pool below the falls, the kinetic energy dissipates, presumably being converted into heat. If this is correct, is the temperature in the pool at the foot of the falls measurably warmer than the water at the top of the falls? and is the water coming out of the hydroelectric generating station cooler?"
Mr. Ward is correct, and the water temperature at the foot of Niagara Falls is indeed warmer than water at the top of the falls, but only by a tenth of a degree Celsius, according to Bryan Karney, a professor in the Department of Civil Engineering at the University of Toronto.
The water coming out of the hydroelectric generating station at the falls is also warmer than the water that entered the hydroelectric turbines, but the warming is much less than through the falls because much of the energy in the water that went through the turbines is used to generate electricity.
Al Buffone from Holland Landing, Ont., asks: "How would the Earth's atmosphere be different in the coming centuries if there had been no climate change or perhaps no industrial revolution? Was the Earth's climate heading in a particular direction before we intervened?"
Sasha Wilson, an Associate Professor in the Department of Earth and Atmospheric Sciences at the University of Alberta in Edmonton, says that for the last million years or so the Earth's climate has been in a consistent cycle of ice ages and interglacial periods lasting roughly 100,000 years. Over that time CO2 levels were also consistent, between 200 and 300 parts per million. Human activity since the industrial revolution has now increased CO2 levels above 400ppm, and may well have broken this cycle as the planet continues to warm.
Christine Hrycun from Simcoe, Ont., asks: "I'm an elementary school teacher and one of my students Nathan wanted to know, 'if a virus doesn't have a nucleus, how does it know how to attack other cells?'"
Viruses are indeed incomplete organisms that don't have a nucleus or organelles typically found in living cells, and so don't have the ability to locomote or follow cues to a target cell according to Charu Kaushic, Professor in Pathology and Molecular Medicine at McMaster University. To hijack a cell, a virus must first be in close proximity to the cell through a largely chance encounter. It then binds to the cell using a lock-and-key mechanism to enter the cell and hijack it to produce more virus.