lisper

But it's not possible to fill in the shorthand unless you already know what it stands for. Hence: the shorthand is not useful for communicating information, only for social signaling.

> a convenient shorthand for the bit that I put in angle brackets above.

Yes, but the "convenient shorthand" only makes sense if you already know what a tensor is. That renders the "definition" useless as an explanation or as pedagogy. It's only useful as a social signal to let others know that you understand what a tensor is (or at least you think you do).

> My favourite explanation is that "Tensors are the facts of the universe"

That's not much better. "The earth revolves around the sun" is a fact of the universe, but that doesn't help me understand what a tensor is.

What matters about tensors are the properties that distinguish them from other mathematical objects, and in particular, what distinguishes them from closely related mathematical objects like vectors and arrays. Finding a cogent description of that on the internet is nearly impossible.

> the reality of the tensor ... is independent of the coordinate system chosen by the observer

Now you're getting closer, but this still misses the mark. What is "the reality of a tensor"? Tensors are mathematical objects. They don't have "reality" any more than numbers do.

> no matter how you choose your coordinates, the bases of the tensor will transform such that it "means" the same thing in your new coordinates as it did in the old ones

That is closer still. But I would go with something more like: tensors are a way to represent vectors so that the representation of a given vector is the same no matter what basis (or coordinate system) you choose for your vector space.

> You might find it circular reasoning but it is not

Um, yes it is. "A foo is an object that transforms as a foo" is a circular definition because it refers to the thing being defined in the definition. That is what "circular definition" means.

> can compilers really execute general code at compile-time?

Cue the smug Lisp weenies laughing quietly in the background.

For a counterpoint see:

https://arxiv.org/pdf/2105.13338

And my own personal take on it:

https://blog.rongarret.info/2014/10/parallel-universes-and-a...

> you'd need a larger and more complex ferry

Don't those already exist? I don't know, but I assume that regular passenger ferries operate on this route, no?

> it would have been a nightmare to wake up everyone at like 3am

I presume that if one were offloading passengers onto an existing ferry one would not schedule the train to arrive during normal ferry operating hours rather than 3AM.

I think the right answer here is that Sicily is bigger than I thought, about 100 miles across, and so the onward travel time can be significant, and so if you're going to offer a night train whose final destination is (say) Marsala then putting the train on a ferry in the middle of the night makes sense.

This is cool, but a little crazy. Why put the whole train on the ferry instead of just offloading the passengers and putting them on the ferry?

And a video: https://www.youtube.com/watch?v=EFRUL7vKdU8

And a video version:

https://www.youtube.com/watch?v=EFRUL7vKdU8&t=11s

Two similar incidents from my career:

https://github.com/rongarret/gll-mag-patch/

https://www.youtube.com/watch?v=_gZK0tW8EhQ&t=2340s

(Also recounted in https://www.corecursive.com/lisp-in-space-with-ron-garret/)

Why wait? Just go read the paper:

https://www.nature.com/articles/s41586-025-09526-6

In the last sentence of the abstract you will find:

"These results ... indicate a viable path to practical quantum advantage."

And in the conclusions:

"Although the random circuits used in the dynamic learning demonstration remain a toy model for Hamiltonians that are of practical relevance, the scheme is readily applicable to real physical systems."

So the press release is a little over-hyped. But this is real progress nonetheless (assuming the results actually hold up).

[UPDATE] It should be noted that this is still a very long way away from cracking RSA. That requires quantum error correction, which this work doesn't address at all. This work is in a completely different regime of quantum computing, looking for practical applications that use a quantum computer to simulate a physical quantum system faster than a classical computer can. The hardware improvements that produced progress in this area might be applicable to QEC some day, this is not direct progress towards implementing Shor's algorithm at all. So your crypto is still safe for the time being.

> They are the "independent" body that enforces Hatch act regulations.

Right. And I have this nifty bridge you might be interested in buying.

Direct link:

https://www.youtube.com/watch?v=ydYDqZQpim8

And here is a live stream from southern Kenya:

https://www.youtube.com/watch?v=XsOU8JnEpNM

and a whole bunch of others:

https://greatplainsconservation.com/live-african-wildlife-we...

It's the same with Apple OS updates. I hardly ever want to update my Apple devices. The odds that such an update will actually improve my UX are indistinguishable from zero nowadays, and the odds that it will break something that I rely on are very nearly 1. (And yes, I get that I'm not getting security updates. That's a risk that I'm wiling to take in order to have an otherwise stable system.) And yet, I cannot get my Apple devices to stop nagging me.

I see what you did there :-)

Oh, come on, now you have to tell the story behind your user name!

Your point is well taken. My guess was that the OP had implementation in mind when they wrote "good voltage sources vary their resistance".

Or that might have just been a mistake.

There are two different ways to produce a voltage source. The first is to put a variable resistor in series with the power source, which you can adjust to control the voltage. This works, but dissipates a lot of heat. The second is to put a switch in series with the power source and a capacitor in parallel with the load, then switch the power source on and off very rapidly and use the duty cycle to control the voltage. This is how modern switching power supplies work. In actual practice, there are also inductors in the circuit which cause resonance, and allow the switching to happen when there is no current flowing through the switch. This is how modern switching power supplies can be so efficient.

No, that's a fair point. It's not really a product, but given what a huge win it was in terms of power/performance I'd say it qualifies.

> AR/VR still feels like 3D tv to me - a solution looking for a problem.

Have you tried the Vision Pro? It was a life-changing experience for me. I actually forgot that I was looking at a screen and thought that I was looking through a transparent visor. It was that good.

If they could get the weight down I'd buy it in a heartbeat. The problem it solves (for me, or at least would solve if it didn't weigh so damned much) is having effectively a giant monitor that I can use on a plane.

Fair point.

> apple watch and airpods

Fair point.

> with large organizations where once their markets mature, everybody who can build a product end-to-end leaves or gets forced out, leaving only people with highly specialized maintenance skillsets

It's not just building a product end-to-end. Tim Cook is a supply-chain guy. He knows how to build a product. What he doesn't know how is how to design a new one. This is the reason that all of the "new" stuff that has come out of Apple since Cook took over is actually just riffs on old degrees of freedom: thinner phones. New colors. Different UI skins. The only thing I can think of that Apple has done in the Cook era that was actually new was the Apple Vision Pro. That was really cool, but it was a commercial disaster, the modern equivalent of the Lisa or the NeXT.

Jobs took Lisa and NeXT failures and turned them into the Mac and OS/X. There is no hint that Apple intends to do anything with the Vision Pro, and they've already been scooped by Meta.

Thomas Jefferson was one person, and he died over 200 years ago.

Very few people say that. Overwhelmingly the rhetoric one hears is that the purpose of higher education is to get a better job.

Personally, I think it would be great if we educated people to cultivate an engaged citizenry. But if we're going to do that we have to be up-front about it an work on an economic model that supports it. So, for example, you can't have student loans that are predicated on being able to obtain a certain level of income on graduation, and you certainly can't make those loans impossible to discharge even in bankruptcy. If you lie about it, as we have been for decades now, it all unravels sooner or later.

Those ten characters are of disproportionately high importance (to put it mildly).

"Numbers. A customization may be desired to allow sorting numbers in numeric order. If strings including numbers are merely sorted alphabetically, the string “A-10” comes before the string “A-2”, which is often not desired. This behavior can be customized, but it is complicated by ambiguities in recognizing numbers within strings (because they may be formatted according to different language conventions). Once each number is recognized, it can be preprocessed to convert it into a format that allows for correct numeric sorting, such as a textual version of the IEEE numeric format."

You are starting to sound like a troll. Yes, unicode has many representations of digits. That has nothing to do with the question of whether 2.jpg should come before or after 10.jpg.

The issue at hand is how numbers are sorted. That has nothing to do with unicode.

Obviously. All I'm saying is that this particular decision ought not to have been taken from the user. Real alphabetical order is not an unreasonable thing to want.