The slashdot poster sounds sympathetic to it as a free speech warning or something, but I don't see how to read it as anything but a threat.

Maybe I missed something.

Very interesting; is there a technical book (or chapter) or paper with a good overview of this comparative aspect of fly neurons?

I was just starting to look around to see what's available on comparative neuroscience in general, based on an interest in the most salient functional differences from human neurons, so anything related to that more general topic would also be welcome.

In theory, if we can capture coherent pictures in the visible spectrum from many billions of light years away, we should be able to do the same with RF.

It's actually very easy to see why the opposite is true: stars famously broadcast a truly vast amount of power in the visible spectrum, which is what makes solar energy and photosynthesis effective.

Humans clearly do not have the power resources of the entire sun to use to power RF broadcasts. The total amount of power we have at our disposal from all sources is a tiny, tiny fraction of what the sun broadcasts.

And most of our power does not go into RF in the first place, it goes into transportation, manufacturing, etc.

So it's quite straightforward that there is no comparison between the brightness of stars in the visible spectrum versus the Earth in RF. Stars win hands down.

It isn't the technology, it's just the hardware.

Unfortunately, it is very much both. It's true that we can do better by building better listening arrays, and SETI has been continually doing that for many years, but there is also a problem of signal to noise ratio that gives a hard limit on sensitivity due to noise from terrestrial sources and from thermal and quantum noise in the receiving electronics.

Part of that could be improved by putting radio telescopes e.g. on the far side of the moon. The electronics issue simply needs better technology.

Yet the sky is not saturated with their communications. So therefor those civilizations must be using some other technology.

That seems logical, but that turns out not to be the case. A SETI scientist said in a talk (and I've seen this in articles since) that our deployed SETI listening technology is still nowhere near sensitive enough to pick up signals even from as close as the nearest star (Proxima Centauri, 4 light years away), if a planet there was broadcasting RF at current Earth levels.

(That doesn't mean SETI to date is pointless, because there's always a chance of a highly directional signal beamed our way, or of just something unexpected, like signals far far brighter than Earth's.)

So no, we have no idea whether the sky is saturated with radio waves or not.

"a bit much" is an idiomatic way in English of saying "possibly you shouldn't have been modded down so much for that statement" (because the first part of what you said is arguable, not an obvious troll, not obviously flamebait, not an obviously incorrect statement of fact).

I think that you being modded down to -1 is a bit much, but there is a problem here. What you said is potentially well and good for contexts that are purely utilitarian to the degree that anything but pure pragmatic functionality is to be viewed as an active negative, such as industrial control, power plants, etc.

But for most people's desktops, people expect both functionality *and* some degree of modern aesthetics, and there is an extremely common rejection of interfaces that look 15 years old, even if they were considered close to ideally functional and aesthetic 15 years ago.

Since that is demonstrably what the market generally wants, that is therefore the general trend over time: "flashy graphics" are sometimes overdone, but the word "flashy" is in the eye of the beholder, and most improvements to GUIs over the decades have been about modernization to meet the moving target of whatever "modern" means in each era, with actual breakthroughs in usability being far less common.

Furthermore, the people who design and implement GUIs are (with the exception of 1-person development teams) rarely the same team members who would address software vulnerabilities, so maybe that's where your -1 came from.

There *is* such a thing as (write, execute), and this is what it is currently using, and people are complaining quite bitterly about it doing that, because it's a security weakness that is exploitable via buffer overflows etc.

Basically the fact that it allows for dynamic JIT compilation is exactly what people don't want the bad guys to be doing; potentially that turns a small bug into a complete take-over-the-machine exploit.

I'm afraid I was taking all that for granted in my original comment, which instead was about potential reasons why they might not have done something different as people are suggesting in hindsight.

I did mean that about time pressure, but I don't understand what you are suggesting.

The scenario is to suppose that they have some audio algorithm that is based on creating and executing a block of code a bunch of times, but for a very small fraction of a second, and then, critical assumption, it needs to create and execute a slightly different block of code, and so on, over and over.

Long ago I saw a demo of an Amiga video capture program that had precisely that sort of thing going on, where they could only get the throughput they needed by using self-modifying code, changing one instruction in an inner loop on a regular basis, and their approach held up under scrutiny of 100 developers critiquing them; it really was needed.

So I am sure that such things do arise in the real world; whether the current codebase truly has such a need, I don't know.

So *if* they have this need, then every time they create or modify a code block, they need it to be writable, but when they execute what they wrote, security issues insist that it it should go from (write,no-execute) to (no-write,execute), every single time.

Making that permissions change requires a system call every time, unavoidably.

Any scheme that allows avoiding that system call is inherently making different assumptions than I did above. Without knowledge of their algorithms, I don't see how we can be sure that assumptions like that are either right or wrong; I'm just pointing out that *if* they are correct, they explain why the codebase does what it does.

An alternative explanation that I tried to give a nod to is that they may have simply done a premature optimization that was not actually needed, but again, motivated as outlined above.

Whether it is noticeably expensive depends on endless details of their code, but if they did extremely fast JIT code generation on a very frequent basis (possibly just a single instruction change), then the reflagging syscall would be equally frequent, and the context switch overhead could dominate.

The scenario under which it truly hurts is possibly unlikely, I'll grant, but at the time of implementation it probably seemed like the simplest and fastest approach, and clearly they were thinking about speed, not security and Return Oriented Programming and such.

Yes, but the re-flagging costs a system call, which is potentially very non-trivial overhead in anything that is using JIT for speed.