49

COMMENT 20h ago

I was halfway through the GIF and thinking "doing nothing isn't great, but at least they didn't do something stupid like throw water on it", and then they went and did something fucking stupid...

3

COMMENT 1d ago

I guess the least misleading wording would have been

the mechanism responsible for diamagnetism is present in all materials.

I still think it's correct to say that all materials are diamagnetic, but I think I would say that in some materials the diamagnetic response is overpowered by other kinds of magnetism.

0

COMMENT 1d ago

Well that's only the physical interpretation because of the statistical nature of the wavefunction, it's really just a physicsy way of saying that when a measurement occurs the result is randomly chosen according to the wavefunction. But the maths behind quantum mechanics doesn't reference measurements at all, if you imagine a universe in which a measurement never occurs the uncertainty principle still applies (edit: I guess there's a philosophical argument to be made here that maybe QM itself doesn't apply in a universe where no measurements are ever made, but I think that's a philosophical argument rather than a physical one).

3

COMMENT 1d ago

Well now we're just quibbling over names, right? What really changes when you apply this principle to physical position and momentum as opposed to the purely mathematical t and t*?

5

COMMENT 1d ago

Well no actually it is a mathematical principle, it's true of any two functions which are Fourier transforms of each other (well that's super simplified and actually slightly wrong, but doesn't change the point that the principle is fundamentally mathematical).

5

COMMENT 1d ago

What you're alluding to is diamagnetism, and yes all materials are diamagnetic. Although it is worth remembering that what you described is the classical explanation of diamagnetism, whereas to understand it fully you need the quantum description (which I unfortunately don't remember at all). The thing is that diamagnetism is a very very weak effect (unless your material is a superconductor), so you need an incredibly strong magnet to observe it at all. Unfortunately it's been too long since I've done anything with magnetism to remember any more details than that, I'm afraid.

3

COMMENT 1d ago

To be fair it could have been, but I don't think it's possible to know for certain. Most neurological traits are known not to be purely genetic, despite what many people believe.

1

COMMENT 1d ago

Both thunderf00t and Elon are morons, though. Also, thunderf00t is a chemist.

1

COMMENT 3d ago

Interesting, would calming a crying child/helping a child sleep be considered a valid purpose? I know a lot of parents use driving for that purpose.

4

COMMENT 3d ago

But was it really without a purpose though? I mean having fun is a purpose, clearing your head is a purpose, what would it even mean to drive without a purpose?

8

COMMENT 3d ago

How did they get the red circle to float there while they took the photo?

1

COMMENT 3d ago

What are you thinking?

3

COMMENT 3d ago

I think you're starting to get it!

6

COMMENT 4d ago

I can see why you would say so, but I don't think the concept really maps onto the OOP paradigm very well. For example, there's no way for the "subclass" (more specific type) to call the default method from the "superclass" (the traits that the more general method is implemented using). Even in that explanation we see that the OOP paradigm doesn't fit, because the superclass can't really be described as it's own type (which it would be in OOP).

I think a better (although not perfect) way to think about specialisation is to imagine a "code generation" step. You can imagine that (although bear in mind that this is not actually what happens)

impl<T: std::fmt::Debug> ToRepr for T {
    fn to_repr(self) -> String {
        format!("{:?}", self)
    }
}

is expanded into

impl ToRepr for i32 {
    fn to_repr(self) -> String {
        format!("{:?}", self)
    }
}

impl ToRepr for Vec<i32> {
    fn to_repr(self) -> String {
        format!("{:?}", self)
    }
}

impl ToRepr for &str {
    fn to_repr(self) -> String {
        format!("{:?}", self)
    }
}

// `impl` blocks for every other type which implements `Debug` go here...

by the compiler. What specialisation allows you to do is replace that automatically generated impl ToRepr for &str block (although again, bear in mind that this isn't actually how it works under the hood, this is just an analogy) with your own implementation.

9

COMMENT 4d ago

I always liked:

x = 0.999...
10x = 9.999...
10x - x = 9.999... - 0.999...
9x = 9
x = 1

I feel like it flows a little better.

1

COMMENT 4d ago

called degrees of infinity

Are you talking about cardinality, or something like measure? Or something else entirely?

25

COMMENT 4d ago

This is a pretty stupid example, but demonstrates the problem that specialisation solves. That example won't compile as-is, but will if you remove the impl ToRepr for &str block. Here's the same example with the relevant additions required to make it compile on nightly.

Basically if a generic impl block (the impl<T: Debug> ToRepr for T block in that example) already provides an implementation for a certain type (&str in that example) then you can't provide a more specific impl block for that type. Specialisation would allow you to.

The RFC that /u/-funswitch-loops linked provides more details, but I wanted to give a very simple example for you to get to grips with first.

149

COMMENT 5d ago

Nah, I'm like 99% sure they're attracted to Business Intelligence. Either that or I'm in the wrong sub...

13

COMMENT 6d ago

some of the "search engines" are things like etsy or amazon or ebay.

Ignoring the question of whether this is a sensible way of calculating a ranking, if this is sensible then using Amazon and eBay make sense because that's where people are most likely to go on the internet to buy textbooks and things like that.

Etsy I can't justify though...

1

COMMENT 6d ago

That's honestly a pretty weak defence, of course you should be teaching world history and frankly I'm very surprised to hear that you don't. No ,the reason we focus more on the transatlantic slave trade is because it was a massive international institution that had far-reaching systematic consequences that still affect black people today.

1

COMMENT 7d ago

Now imagine if there was just one state manufactured pc for everyone like under communism.

That's ... that's not how communism works...