there are 3 sources of energy on the surface of earth:

• energy from inside earth (geological heat)
• energy from the moon (tides can make water go up and down -> generates energy)
• energy from the sun (and hypothetically, other stars)

so, the thing is that earth’s internal heat generates 0.03% of the energy on the surface of Earth (source) while i couldn’t find any numbers for the moon (so i guess it’s too low to mention). so basically everything comes from the sun.

and this is true for living beings. living beings can live off the sun’s energy (photosynthesis) or they don’t, in which case they’re utilizing Earth’s internal processes (volcanoes, …) as an energy source.

basically all life was dependent on energy from inside the Earth before photosynthesis was developed, which is severely restricted. this is why this is such a big breakthrough.

a knot is a nautical mile per hour

yeah making content is a lot of work. i can’t blame them.

i’m too young for that :D

it’s highly unlikely, fluids stick together and make drops in the air which you can easily see and avoid. and also, come on, women getting accidentally impregnated by sperm floating through the air is even less likely that women getting accidentally impregnated by sperm swimming in the water of the public swimming pool …

i think they took a list of all publicly accessible fediverse instances and then just looked up the IP address for each of them, and then the geographic location for each IP address. most of this process could be automated somehow, but you still need to create the website and the hella cool intro :D

different fediverse services

space elevators aren’t feasible, but a space pyramid is. just build a really tall pyramid, some kilometres high, it would work. though expensive.

I have written a post about exactly this phenomenon, arguing that that’s how most animals/insects see the world (assuming their sense of vision isn’t good enough or they just don’t care to look up). Apparently i was wrong, even insects can see the stars and navigate due to their light (milky way navigation).

If the planet is massive enough, getting to orbit becomes a real challenge because fuel consumption scales roughly exponentially with the mass of a planet (delta-v formula, rocket equation).

This leads to an almost sharp cut-off for the maximum mass that a planet can have so that a rocket which utilizes chemical fuel (e.g. methane+oxygen) can still reach orbit successfully. This maximum mass is roughly 10^26 kg.

For reference: Earth’s mass is around 6*10^24 kg.

While other propulsion types exist, such as nuclear + ion drive, these propulsion types are significantly more complicated.

Interestingly, if a planet is too small, it cannot hold an atmosphere. There is a surprisingly sharp cut-off minimum mass for this as well, at roughly 10^21 kg.

You know what, i keep thinking that maybe, our universe is the only universe that actually functions. Like, if the universe was in some different way, it either wouldn’t work and we would therefore not exist to observe it, or it would be equivalent to this universe, i.e. maybe not exactly equal, but similar in some way, sothat we could form abstractions and arrive at the same universal laws that we have today. Including quantum mechanics.

What does “understanding” mean in this context?

I can perfectly fine do the calculations; That’s what “understanding” is, in my opinion. Feynman might be hitting on some metaphysical concept, but then again, what is that metaphysical concept, is it any different from pseudoscience, and do we really need it?

Idk i keep asking myself, how would it feel like to have 6 fingers, and are you able to move them all? Idk it just seems weird, but then i remember that i have 5 fingers too and i can move them just fine. So i guess it’s intuitive somehow?

To be honest, i’m not sure what you want.

Like, if i was the student, i think i would be extremely confused from this lesson. I would not know what you want from me. I have had my fair share of teachers trying to get me to “just think about something and figure stuff out myself” which mostly amounted to me sitting there in classroom, staring into the air, confused about what the task is, and mostly waiting till the hour is over.

My brain works differently. When i learn something, before i even start caring about what the topic is, i ask why I’m learning this; and i need to have a proper reason to learn something. The reason needs to be strong enough, and is only strong enough if it is derived from some other, stronger reason. For example, i learned maths because i understood how important it is to grasp the universal, those things that cannot be taken away from us. I grew up in a kinda abusive household, and my mother had a habit of taking away the things that were most precious to me, so i clinged on to maths because i knew that maths was eternal and not dependent on the whims of my mother. That is a clear, practical reason. Maths gives me mental stability, like a skeleton gives stability to the body. It does not shake nor break; for it’s eternal.

Now, if you want me to play around with polynomials, idk what i would do.

Typically, when i learn something, i want to know why but also how to learn something. Especially, to express it in an analogy, my brain is like the C programming language. I need to reserve memory manually, it does not happen automatically, and i need to know how much space will be needed beforehand, in other words i need to have a clear understanding of how big a topic will be before i actually start learning it. When i have no idea what i’m getting myself into, then i don’t get into it, because my brain is very very very (i hope i have made this clear enough) bad at learning many small incremental pieces of knowledge. In fact, it’s similar to if you had to put on your jacket, leave the building, go through the cold icy air into the neighboring building each time you want to get yourself a glass of water. Needless to say, you will not drink a lot of water. You will dehydrate. Obviously you would put yourself a large bottle of water into your room, for which you only have to leave the building once. The same applies to me and learning. I have to take very few, appropriately sized portions of knowledge into me at once. Not many many small ones.

Polynomials:

They exist because they are efficient to compute. Computers do well with basic arithmetic operations like addition (+) and multiplication (*). The polynomial functions are simply those that you can construct from those two operations, and constant numbers.

Like consider a polynomial like f(x) = 5x^3 + 3x^2 + 2x + 7

What it really says is f(x) = 5*x*x*x + 3*x*x + 2*x + 7 and here you can see how it’s all built from + and *.

This is why polynomials are useful. Because computers have an easy time calculating them. And all modern mathematics is done on computers. All the engineering uses computer simulations, and we want these simulations to run fast on computer hardware, so we make it easy for computer hardware to do. That is why we’re using polynomials wherever we can.

That is how you explain polynomials to 8th graders. No taylor series / calculus needed.

If you want to be really fancy you can show the taylor series of the sine and cosine function as a polynomial and how to compute it on a computer. Gives some pretty graphs, is simple and fun.

Just tell them that polynomials can be used to computer sin and cos functions without going into the details of why that works first.

Edit: Just to clarify this: Yes i think that explaining why students should learn stuff is extremely important. In fact i tend to say that the only thing that you really have to do is to motivate the students to learn; then the learning happens by itself.

However note that giving esoteric abstract playful descriptions of things in my opinion does not motivate people to learn stuff. That just makes them go “huh, neat but useless”. Giving real world practical examples fulfills exactly the purpose of giving students a reason to learn stuff. Because seeing how one can solve real problems with the tools, one learns to value the tools.

Maths education is pointlessly overcomplicated. We need to simplify and streamline it. And also add in more practical real-world examples.

you could set the spaceship in rotating motion, sothat the centripetal forces push you outwards and create the impression of artificial gravity for you.

besides, why does no spaceship seem to be doing this today, like, at all?

Can you swallow things when you’re laying flat? I imagine swallowing food in space would be no more difficult.

it’s especially cool how close the moon feels. as if it’s finally in reach again.

friend is stuck on his iPhone

my honest opinion is that it’s a lost cause. people superficial enough to be on an iphone in the first place probably aren’t gonna think through the deeper ramifications of privacy and information security practices at all.