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Answering your hypothetical questions with physics, every Tuesday.

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Comet Ice

Could I cool down the Earth by capturing a comet and dropping it in the ocean, like an ice cube in a glass of water? Daniel Becker No. In fact, it's honestly sort of impressive to find a solution that would actively make the problem worse in so many different ways. Dropping a comet into the ocean to cool the planet, famously suggested by the 2002...

Star Ownership

If every country's airspace extended up forever, which country would own the largest percentage of the galaxy at any given time? Reuven Lazarus Today's question is adapted from What If 2: Additional Serious Scientific Answers to Absurd Hypothetical Questions, which contains many more What If answers and is available now! Congratulations to Australia,...

Transatlantic Car Rental

My daughter recently received her driver's permit in the US, and aspires to visit mainland Europe someday. She has learned enough about the rules of the road to know never to drive into the ocean; however, she jokingly suggested that given a sufficient quantity of rental cars, she could eventually get to Europe by driving east repeatedly. The question...

Hailstones

My 4 year old son and I were wondering about soccer ball sized hail today. How much damage would a hail storm with size 5 soccer ball sized hail do? Michael Grill When you think about it, it's honestly kind of weird that hailstones haven't killed all of us already. I mean, they're chunks of ice that plunge from the sky! Hailstones fall from really...

Hot Banana

I heard that bananas are radioactive. If they are radioactive, then they radiate energy. How many bananas would you need to power a house? Kang JI Bananas are radioactive. But don't worry, it's fine. Bananas are radioactive because they contain potassium, some of which is the radioactive isotope potassium-40. The factoid about banana radioactivity...

Earth-Moon Fire Pole

Earth-Moon Fire Pole My son (5y) asked me today: If there were a kind of a fireman's pole from the Moon down to the Earth, how long would it take to slide all the way from the Moon to the Earth? Ramon Schönborn, Germany First, let's get a few things out of the way: In real life, we can't put a metal pole between the Earth and the Moon.[1]For one,...

Electrofishing for Whales

Electrofishing for Whales I used to work on a fisheries crew where we would use an electro-fisher backpack to momentarily stun small fish (30 - 100 mm length) so we could scoop them up with nets to identify and measure them. The larger fish tended to be stunned for slightly longer because of their larger surface area but I don't imagine this relationship...

Toaster vs. Freezer

Toaster vs. Freezer Would a toaster still work in a freezer? —My Brother, My Brother and Me, Episode 343, discussing a Yahoo Answers question On a recent episode of Justin, Travis, and Griffin McElroy's terrific advice podcast, My Brother, My Brother and Me, the brothers pondered a Yahoo Answers question about what would happen if you put a toaster...

Coast-to-Coast Coasting

Coast-to-Coast Coasting What if the entire continental US was on a decreasing slope from West to East. How steep would the slope have to be to sustain the momentum needed to ride a bicycle the entire distance without pedaling? —Brandon Rooks Too steep to actually build, sadly. But for the next best thing, I suggest a vacation to the Hawaiian island...

Hide the Atmosphere

Hide the Atmosphere Earth’s atmosphere is really thin compared to the radius of the Earth. How big a hole do I need to dig before people suffocate? —Sam Burke The idea here is straightforward: When you dig a hole in the ground, the hole fills up with air.[1]The dirt you pile up outside the hole displaces air, so at first you won't have much effect...

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