u/Traditional-Role-554

i dont care about anything other than the fusion part because why is it called fusion? i got one answer that says fusion refers to both the forward and backwards change of state between solid and liquid, although i would like to fact check that in some way. especially since that would imply vaporization refers to both changes of state between gas and liquid due to specific latent heat of vaporization, but calling condensation vaporization feels very wrong

surely its not a coincidence that its a combination of linear momentum and angular momentum right? momentum=mass*velocity, angular velocity=velocity/radius F=(mv^2)/r

you know how a ballerina spinning with her arms out spins relatively slowly but as they pull their arms in they reach crazy speeds? i know it is a common demonstration of conservation of angular momentum but i'm not entirely sure as to how it works.

my main theories are it is either that the radius of the turn decrease so angular velocity increase, or the mass concentration at the centre increases and that causes the angular momentum at the centre to be greater although i see no reason as to why that affects the speed.

since light is an electromagnetic wave i would expect that it would only be affected by changes in the electromagnetic field, which i would not expect could be influenced by gravity. especially since gravity and electromagnetism are both fundamental forces that act as deformities in space-time and electromagnetic fields, i would have assumed they are entirely separate from one another.

is it something to do with light being a particle as well as a wave meaning it should be influenced by gravity.

I’ve signed up and booked for the upcoming open day and I’ve gotten a confirmation email that says they’re expecting me, but I know lots of uni‘s send you a QR code that you use to register once you’re there and I didn’t get anything of the sort.

do I literally just show up? I have some kind of email that says they’re expecting look forward to seeing me so I’ve definitely booked.

the line is in reference to galilean relativity and is talking about transformations of X(t) from reference frames S to S',

"rotations:X'=RX, for a 3x3 orthogonal matrix R obeying (R^T)R=1 (but its some weird 1 in the same style as the ℝ symbol)"

i have literally started looking at matrices today so i think the weird 1 might be the identity matrix?

but i have almost basically no idea what an orthogonal matrix is

any help is appreciated.

what are the main problems with dark matter? i know that the biggest one is meant to be just a lack of evidence since it's literally invisible but where does it fail, what does it conflict with established theories and predictions?

doing a presentation about dark matter and i need to talk about some alternatives like MOND theory. any sources would be appreciated (i will obviously check them and properly reference all sources of information so there is plagiarism going on). in your opinion what are your favourite theories to explain things like the missing mass problem other than dark matter?

quick side note: does dark matter theory conflict with the hubble constant? i saw a source that said if dark matter theory were to be true the universe shouldn't be expanding as fast but after searching for it again i couldn't find a single site repeating it.

i've seen them before but all i know is they have something to do with coordinates and i think the number of columns and rows corresponds to the number of dimensions? what are they and how are they used in mechanics?

i guess i should be asking why causality has a speed really but either way, why does light have to have a speed to begin with and why must it be constant. 300,000km/s seems so random and something like light seems like it should travel instantaneously. also why is that speed 300,000km/s.

i'm writing about dark matter and had a thought, could a substance made entirely of neutrons reflect light? i wouldn't expect it could produce light but that also leads me to believe it wouldn't interact with it in any capacity since it has no charge and therefore shouldn't interact with any electromagnetic force. just to get into a bit of crack pot science, do you think its at all possible that this dark matter could be some kind of neutron material? would love to hear peoples thoughts.

every now and again i see someone with arms that look like they're just covered in wrinkles or the skin had become super tight and stretched. are they all just small scars or does the skin actually stretch when healing

i^2=-1, fair enough, but then what actually is i? does it have an approximation like pi and e? to me it just feels like putting i into an equation is like saying "this equation isn't possible, but if it was it would look something like this". it feels similar to infinity as in it's not an actual number just a useful concept to help solve some equations.

take BCl3 for example, one atom making three polar bonds. how is it that those bonds "cancel out", do they literally cancel out and create non polar bonds, or is it more since it is surrounded by partial negative charge, its not actually polar. but surely it should still be able to form bonds with polar molecules in that case since at that points its essentially just a charged molecule?

im guessing not but i have no idea why so it feels like a reasonable question. And if not why is the max three and why are mesons fine to have only 2?

so I’m kind of familiar with electrons in an atom being a standing wave but im not super confident on it. Ik that’s it’s meant to work into the discrete energy levels of the electrons since like those energy levels only certain wavelengths of standing waves are possible, but I don’t really understand how those two concepts meet, to me it feels more like a cool coincidence than any real physics.

how do electrons form standing waves in an atom and how does that fit into the energy levels? cheers

outside of the immense pressures inside a neutron star neutrons don't seem to want to stay together that much which is weird since they have no charge, so I would think they would be love to stay together via the strong nuclear even if it was only very small molecules with only 2 or 3 neutrons?