Here is an AI-generated summary of this video for the people who don’t want to go to YouTube with an added ELI5:
In this video, the host, Destin, explores why cats always land on their feet, a phenomenon known as the ‘cat righting reflex’. He uses a cat named Gigi as an example and employs a high-speed camera to analyze the process.
Destin explains that when a cat falls, the first thing it does is try to figure out which way is up. It does this using the balance organ in its ear or its eyes. Then, the cat divides its body into two separate rotation axes that are tilted from each other. It pulls in its front paws, decreasing its moment of inertia at the front so it can spin quickly. At the same time, it extends its back legs, increasing its moment of inertia at the back, resulting in a smaller twist in the opposite direction. In this way, the cat compensates for the rotation and lands safely on its feet.
Destin emphasizes that cats have very flexible spines and no functioning collarbones, which contributes to their ability to perform this complex movement. He also notes that this phenomenon has baffled scientists and engineers for centuries and is studied in various fields, including physics, robotics, space satellite control, weapons development, and biomedical engineering.
The video ends with Destin playfully chasing Gigi and thanking the viewers for their attention. He encourages viewers to check out other cat videos and subscribe to his channel, Smarter Every Day.
ELI5 (Explain Like I’m 5): Imagine you’re a cat and you’re falling. You quickly figure out which way is up and down. Then, you do a clever trick. You pull your front legs close to your body and push your back legs away. This makes your front body spin fast and your back body spin slow, but in the opposite direction. It’s like when you see ice-skaters spin really fast when they pull their arms in. Once you’ve twisted enough to face downwards, you just stretch out all your legs and get ready to land on your feet. It’s a cool trick that cats can do thanks to their super flexible bodies!
Basically, the moon acted like a spinning (unbalanced) wheel, and eventually stopped with the “heavy” side pointing “down” towards Earth. I.e. think of the moon as orbiting Earth with the heavy side staying pointed at Earth.
Try recreating that spin with a fidget spinner and slowly turn it around like the moon turns to face earth. You’ll find that it wants to turn in a way where it spins around the same axis it’s orbiting.
Since the moon has no hand preventing it from doing that, it aligns its spin with the orbit, so the forces described in the article bring that rotation to a halt.
To really blow your mind, the Moon is slowly moving away, but will never escape. Eventually both the Earth and the Moon will become tidally locked to each other at which point the Moon will no longer move further away. This assumes no outside influences and enough time.
Not my field, but I don't think it's even possible to really pinpoint "the" most recent evolutionary step, not to mention being able to define "step" in an incredibly slow variable with multiple layers of continuity (individual, population, and whole species levels).
But I would say that it is very recent for sure, as lactase persistence is a trait that really only started (above "noise" level stochastic mutations in the population) when we started using dairy some 6000 years ago because of selection pressure.
So, the purveyor of the electromagnetic force is the photon, as in visible light and radiation. If you look into it you find talk of “virtual photons” being the purveyors of magnetic force, but it seems they are more of a mathematical construct, and if you read enough about it, it becomes clear that it’s a whole lot of technical language that boils down to, “we dunno”.
All the large moons in the solar system are tidally locked to their planet!
Pluto and Charon are tidally locked to each other!
The earth would eventually be tidally locked to the moon too, but because it’s happening so slowly, it wouldn’t happen before the sun turns into a red giant and engulf both!
There is such a huge difference in the masses of the earth and moon that although the moon is slowing the rotation of the earth, the earth’s rotation is also speeding up the moon’s orbit. The faster orbit is causing the moon to move farther away from the earth.
Frankly, the decisions that we make are chemical reactions. The difference is in the complexity of the decisions that we can make. At that point, though, in order to answer your question, we would need to argue about what one would consider to be a decision that’s complex enough and a decision that’s not complex enough, and that leans much more into philosophy and ethics rather than science.
I can only tell you that, from a mechanistic point of view, there’s not really much distinguishing our decision making process from, say, the decision making of a flatworm
Abandon the philosopical concept of an independent thinking mind capable of evaluating something by itself.
“Decisions” and “Thoughts” don’t exist without the environment, as they’re a succession of neuronal activation cascades in response to the current state of all stimulus, the previous connections formed in your brain, and reinforced patterns.
Leave a human being in an empty void and their thoughts will be built by severely boosting sensitivity and then responding to random sensory noise. Sever all sensory connections and the mind shuts down.
You've stumbled upon the basis of the debate between free will and determinism. imo, we are merely under the illusion that we're making our own choices. The universe is one infinitely complex system of falling dominoes, with each choice and action just being the result of the parameters set by the ones preceding it. We are all made up of the same basic building blocks, and are thus just subatomic systems obeying the laws of thermodynamics... it just happens to be the case that when a system reaches a certain level of complexity, it is able to think about itself - we are quite literally the universe experiencing its own existence.
Why is this? I don't know. Nobody knows. Consciousness and 'the ability to experience' is one of the most elusive and complex questions facing science and philosophy today. It's my personal belief that there is certainly 'something' more to this whole cosmic experience, but I'm not convinced by religion's answers and believe 'it' to be something so vastly incomprehensible and foreign, we'd never understand it even if the mystery were revealed to us. It isn't something I like to think about too deeply, because unfortunately, it opens up an infinite regress of questions we will likely never have the answers to.
Quite frankly, all of them, as in literally all of the levels. e.g., viruses are not considered "alive" in the classic sense, but they sense things sometimes & change their behavior accordingly. A single protein can do it too, like in mad cow disease / scrappy (called "prions"). Even a tiny snippet of DNA can make logical circuits akin to computer ones, implementing AND, OR, XOR, NOR, operations etc., plus feed-forward loops (& feed-backwards, and all other sorts).
Possibly even subatomic particles, and maybe even quarks (or strings?) do the same - e.g. the Heisenberg Uncertainty Principle where you start to interact with something and then that changes it already so that you cannot measure other aspects of its previous "natural state". Okay that's not so much a "decision" as a "reaction" - but as you are questioning, what really distinguishes the two, REALLY?
Bacteria can sense a molecule (like sugar), literally start growing a tail (no joke!), and then swim towards it. All entirely chemically, and we have the technology to literally just kinda 3-D print all that at the molecular level (it takes an existing flagellum but once that is added to the mix, it can grow just like a crystal, by extension / copying of the old pattern).
Most of what we considered to have made humans "special" in the word turned out to be false - e.g. chimps & gorillas can "talk" (it's hard for their throats to make our kinds of sounds, but given the right apparatus they can get the job done), and think in abstract terms, and do math, and all kinds of things. Of course, humans ARE special - we are the only things on planet earth that if aliens came, could attempt to nuke them in orbit, and we literally light up the night sky! But there's a whole continuum of "dust" that share a lot of properties with us, in various ways. I'm not sure if animals have the same kind of subconscious vs. conscious interplay going on as we do, but if you have a pet and stare at it trying to work through a decision, you KNOW that it's doing the same as us, at a fundamental level. And then each time you go a level deeper, the similarities kinda never end...
Such questions may never even find answers, at least in our lifetimes, but it sure does seem worthwhile to ask anyway... it sharpens us, so keep digging!:-)
It’s not some force keeping them the same, it’s no force changes the speed of the moon. From my limited understanding the moon was created when a smaller planet crashed into the earth:
They both got the same momentum, therefor they started rotating at the same speed, once per day.
There is nothing out there which would be able to change the speed of the rotation of the moon. There is also nothing which would change the speed of the rotation of the earth. Therefor they keep spinning at the same speed.
Other people have explained it, and the same thing happens with other moons in the solar system, including some orbiting gas giants where your explanation couldn’t have worked.
The Earth’s gravitational field elongates the moon slightly, and an elongated satellite tends more to stabilize its rotation with the longer diameter fixed to point at the center of its orbit.
I don’t have the study to back this up, but personally for me it has a lot to do with how heavy I am. When I’ve been thinner I’ve been much more tolerant of humidity and heat.
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