10 What Is Life?
Given that we are alive, everyone we know is alive, all our pets and food are or were alive, and essentially the entire surface of our planet is alive, you might be surprised to know that we still haven’t come up with a definition for what life is. Or rather, we’ve come up with hundreds, and none of them work. Watch this video on YouTube One criterion is that life maintains internal homeostasis, but so does a smart AC/heating unit. Another is being composed of cells, but lipids spontaneously form vesicles in water without any life or genetic instruction. Another is the ability to reproduce, but 99.99% of ants on the planet can’t reproduce; are they not alive? There’s also the tricky fact that viruses are not considered alive, despite being organic, self-arranging, having genes, replicating themselves, and evolving by natural selection. Because they need a host and also don’t metabolize, we don’t consider them alive. Then again, we don’t know what is and what isn’t.
9 Why Do We Sleep?
You get a pretty short run on Earth as a living being, and for some reason, we spend a full third of it unconscious (and hopefully not much more). Sleep makes little sense evolutionarily. Whatever benefits it bestows have to be weighed against losing one-third of your food-finding and sex-finding time. Not to mention, we, therefore, spend one-third of our time wildly susceptible to predation. So why do we sleep? Watch this video on YouTube We don’t yet know. We’ve discovered many benefits of sleep, including memory-building, hormone-regulation, and passive skill-building, but the question remains: why do we have to be unconscious for it? Some animals, like dolphins, switch off half of their brain at a time; half is always active and alert. Others sleep fully but only need a couple of hours. It must be true that our ancestors who laid unconscious for hours on end were more likely to be eaten and therefore less likely to spread the genes for a longer, deeper sleep. So how did it spread? Another way to ask that question is: what unknown benefit of sleep makes it worth it?
8 Does Time Exist?
You can check your watch and watch time flow, so it must be something. But is it the type of something we invented or a fundamental facet of the universe like mass and energy? Physicists are divided into two camps: those that say it exists but don’t know how and those that don’t think it exists at all (I should note that most fall into the first camp). Watch this video on YouTube Scientists often consider time the fourth dimension: any object can be assigned four numbers based on its position (X, Y, and Z) and time. But general relativity holds that the time value is different for different observers, as gravity can distort and dilate time differently from place to place. So, if every observer of a point in time has a different definition of time, then does that time have a definition at all? Some physicists think the answer is no, that we merely project sequences onto events to better understand them for the simple fact that our perception is imperfect.
7 Why Does Handedness Exist?
For some reason, humans prefer to use one hand over the other. The reason why is still a mystery. For some other reason, about 85-90% of people prefer their right hand and only 10-15% the left. That is also a mystery. More mysteries follow, like the fact that other animals, such as dogs, cats, and kangaroos, have handedness. So what is going on? Watch this video on YouTube No one really knows. Convincing arguments exist as to why the vast majority of people prefer the same hand. As tool use and modification became an everyday part of survival, and because we’re social animals, it makes sense that we should fashion tools in the most universal and sharable way. But that only makes sense if handedness for both hands already existed, and how did that happen? And why the right over the left? And if the right is so decidedly more advantageous, how do 10-15% stubbornly hold on to their lefty ways?
6 The Number of Planets in the Solar System
This isn’t some foolishly defiant conspiracy that Pluto is a planet because it isn’t (Jerry); it’s a dwarf planet. But even though Pluto lost its status as the ninth planet, many astronomers believe another planet should rightly hold the title. Watch this video on YouTube There have been dozens of theoretical planets in the Solar System beyond Neptune. Pluto itself was purely theoretical for a long time. Though scientists have debunked many of these potential candidates, they perpetually propose new versions, and with good reason: things don’t add up beyond Neptune. Many objects beyond Neptune, mainly dwarf planets and minor planets, are arranged with an odd amount of asymmetry. In other words, not random and even like you’d expect. Instead, it seems as if a large body beyond Neptune is pulling these objects around with its gravity, and many call this large body planet nine.
5 What Are Fingerprints?
Like handedness, our fingerprints are so universal and banal that we tend not to question their existence. They’re just little ridges on the tips of our fingers. What is the mystery? There are a few mysteries, actually. For one thing, fingerprints are almost perfectly unique from person to person. Even identical twins have different fingerprints. We have no idea how or why. And while an explanation could involve the randomness of development and lifestyle, that is disproven by the fact that your fingerprints stay in the exact same pattern your entire life. They develop completely unique and are then locked in. And we don’t know when or why they developed. An obvious theory was to help grip when climbing trees, but studies have shown that fingerprints can reduce grip by allowing less skin to grab an object, thereby reducing friction. And even if it was true, why would they be unique to every person?
4 Why Does Physics Just Break Sometimes?
Just when physicists thought they were getting somewhere, along came quantum entanglement. It’s so baffling that Einstein labeled it “spooky action at a distance.” Watch this video on YouTube At its most basic, entanglement is the phenomenon wherein two particles are linked so that anything that affects one affects the other. Even if they’re separated by distance. For example, individual photons can split into a pair of entangled photons. If we took one of those photons to the next room, or even miles, whole galaxies away, and something affected that photon, it would still instantaneously (or at least well beyond the speed of light) affect the other photon. That means a signal is exchanged between the two particles faster than the speed of light, which should be impossible. And yet, here we are.
3 Um… Turtles?
Of all the questions that evolution has yet to answer, one of the most surprising is the origin of turtles. In recent years, with more advanced genetic and developmental technology and the continual discovery of more fossil evidence, we’re getting closer to an answer. But somehow, we still aren’t there. This isn’t quantum science. This is turtles. It’s surprising we still don’t know. Watch this video on YouTube Turtles are incredibly unique from a skeletal perspective. Their shells are made from wildly modified ribs, vertebrae, and pelvic bones. The bones grow beneath the turtle’s skin and are covered in a layer of keratin, the protein that makes up our nails. They’re also anapsids, meaning they don’t have a type of hole in their heads that basically every other vertebrate has. None of their closest relatives, which we still debate back and forth, have features even remotely close to these. It’s such an odd and extreme adaptation that with so little evidence of transitional forms, turtles remain an open question.
2 What Is Most of the Universe Made Of?
We tend to think that the universe is empty (we do call it space), aside from the oases of planets, stars, and the like. But the mass of every one of those objects, all matter, only accounts for less than 5% of the universe. The other 95% of the universe is dark matter and dark energy, and we have no idea what these dark things are. We only know how much there is because we can detect it as it affects the universe’s expansion. Watch this video on YouTube We know it doesn’t make up the planets and stars and the rest. We know it’s not antimatter either because we can detect the explosive interactions between antimatter and matter. There are few other knowns. Most are left to competing theories, but with so little evidence to base them, it’s doubtful any will win the debate anytime soon.
1 What in the Heck Is Gravity?
Blood, Sweat, and Tears sang it best, “What goes up must come down.” We just have no idea how or why. It’s true, the fundamental force that is gravity, so obvious that children understand its basic rules almost immediately, is actually one of the biggest mysteries in all of science. Watch this video on YouTube Newton gave us a robust equation for predicting and calculating gravity by describing it as a force. Then Einstein gave us a plausible explanation for its existence, saying it isn’t a force at all, but rather the consequence of mass curving spacetime. Then both particle physics and quantum mechanics argued that gravity as we know it either makes no sense or needs more work. Mass, energy, and all three other fundamental forces are made from particles, but gravity isn’t. At least not as far as we can tell. The theoretical ‘graviton’ remains undiscovered if it exists at all.
