Why can we only hear certain frequencies? Our cochlea is only stimulated by frequencies between 20 Hertz and 20,000 Hertz. First, let’s look at how we actually hear. Our ear is a detector for sound waves. It is shaped to funnel them into the ear canal, which ends in the eardrum. The sound waves make […]
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Where does space end? There is no way of knowing, but there is a horizon 46 billion light years away that we can’t see past. There are five different possibilities. That the universe is infinite. That the universe wraps in on itself. That there is no “outside” to the universe. That our universe is embedded
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Where does space start? Technically, it starts at 100 km, but there are five different definitions. Space begins at the Kármán Line, which is 100 kilometers above sea level. There is obviously no sign that says, “Welcome to Space!”, so any line that shows the boundary of space has to be arbitrary. The reasoning behind
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When were the first binmen? Technically, in England in the 14th century. Trash is a tremendous problem in the world at the moment. Our refuse sites are full, we release dangerous chemicals when we burn trash, and the sea is full of plastic trash. It is easy to think that the problem of trash has
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How do hummingbirds flap their wings so fast? By having very strong, fast twitch chest muscles, by twisting their wings instead of flapping them, and by being able to use oxygen and energy very quickly. There are 361 species of hummingbird altogether. The smallest species grow to about 5 cm and weigh 2 grams The
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How does a photocopier work? They work because light carries energy and opposite electric charges attract. The first principle that the photocopier relies on is that light carries energy. Light is a little difficult to understand. According to Einstein, anything that travels at the speed of light cannot have any mass. If something has mass
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How big was the asteroid that killed the dinosaurs? It was probably 10 km across, but it could have been anywhere between 10 and 17 km. The asteroid that killed the dinosaurs hit Earth about 66 million years ago. Apparently, according to research, it was 66,043,000 (±11,000 years). The asteroid came down in the Yucatan
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Why do ant bites hurt? Ants both bite and sting. They drip formic acid onto your skin and some ants inject venom. Not all ants bite. There are estimated to be 22,000 different species of ant and they are on pretty much every landmass except for Antarctica. It is estimated that ants make up between
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Could nuclear fusion power the Earth? Yes, but not in this half of the 21st century. Nuclear fusion and nuclear fission are the two ways we can get energy out of an atom. Nuclear fission is the easiest of the two for us to perform on Earth. In nuclear fission, a neutron is fired at
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When did people start using punctuation? The Greeks were the first people to use punctuation, but the Bible made it commonplace. Most early languages used a writing system that was based on images. There was no need for punctuation or even spaces because the ideas were contained in the symbols. Modern languages like Japanese and
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