The Science Topic

[Adsolution]

maybe photoreceptor cells are quick to activate but slow to deactivate, or maybe my brain is filtering out the artefacts.

I would take this to be the case, much like fluorescence.

[PluMGMK]

Well, it's certainly the case for electronic photodetectors. Photons come in and generate electron-hole pairs, which you've got to sweep up as efficiently as possible to avoid artefacts. I only mention this because that was the bane of my life a few years ago, but it's good to know the biological analogue (which I presume involves the creation and movement of neurotransmitters…) can be a feature rather than a bug.

Now you guys have made me wanna read more about biological photosensors…

[PluMGMK]

Random "scientific" thoughts of the day, which at this late hour my mind tells me justify a double post…

I do believe I had an experience of jamais vu last night. I woke up from some dream and became aware that there was a soft black cat sitting on my bed. Of course, it was my little cat "Tuesday", she often sleeps on my bed at night. But for some reason, at that time, I couldn't identify her at all, it was just some cat sitting on my bed. But I wasn't awake enough to be upset by that…

The other thing is about the electric vehicle equivalent of "miles per gallon", which is "kilowatt-hours per 100 km". I realized yesterday that that's technically a unit of force, equivalent to 36 newtons. So when my car is showing me a rolling average of the "kWh/100 km" figure, that's kind of a measure of the forward force being applied to the vehicle at that moment in time. Of course it's not really, since there's some efficiency factor in there, which probably depends on driving conditions itself, but I found it a fun train of thought while cruising along

[PluMGMK]

OK, triple post incoming, but hey, this topic has been dead for well over a year now…

I came across an interesting essay the other day about how the "random mutations plus natural selection" theory for species evolution doesn't stack up with the evidence available today: Why did Darwin's 20th-century followers get evolution so wrong? | Aeon Essays I guess it's more than just "basically statistics" as I once claimed elsewhere on the forum (at a time in my life when I was learning about and starting to utilize stochastic optimization algorithms )! In fairness, it really couldn't have been, given that if that were the case there wouldn't be enough time for us to have evolved since the Earth was formed!

Also, my Biology teacher always decried the term "junk DNA", saying that sooner or later we would realize it does have a purpose, which of course it does! I guess at least some teachers uphold their "responsibility to prepare their students for inevitable surprises."

[DaveRattlehead]

Now that you mention it, I remember my biology professor saying something similar... There are many things to discover about non-coding DNA! I have no doubt that this scientific field is going to give us more than one surprise in the future

Btw, I didn't know this topic even existed... It's interesting, I guess.

[PluMGMK]

Now that you mention it, I remember my biology professor saying something similar... There are many things to discover about non-coding DNA! I have no doubt that this scientific field is going to give us more than one surprise in the future

That's good! Maybe teachers aren't as delinquent as the author seemed to think

Btw, I didn't know this topic even existed... It's interesting, I guess.

Yeah, it's never been particularly active I don't think… Maybe it's too broad, but then having a "topic of the week/month/whatever" didn't exactly work out either

[Maz]

Can't find the source anymore, but on a related note, I thought it was interesting to mention that humans are actually influencing evolution as well. I recently read somewhere that there's some region where elefants "evolved" to the point of not having tusks anymore. Reason being that elefants with tusks get poached and the elefants which survive and pass on their genes are, for the most part, those which had no tusks to begin with and therefore weren't hunted.

[DaveRattlehead]

Not the kind of person that shows off quite a lot, but I'm not going to hide that I'm really proud about this... Today I've started writing my very first paper! There's still a long way to go as it isn't an easy task and I'll probably have to correct many things while I'm writing it, but luckily I'll see my "son" published somewhere in a few months (if everything goes in the right direction)

[Immortalia]

Ayy good luck you've got this!! I hope your writing goes well.

[Reese Riverson]

Umm… Maybe this should be continued on the Science Topic or similar?

Your wish is my command, PluM.

Anyway, continuation from here:
https://raymanpc.com/forum/viewtopic.ph ... 2#p1471462

But anything that needs 240 V needs to be specially wired, right? You can't just plug it into the wall?

Also, black being hot… Damn…

Generally yes, you would have a specific style of outlet wired up for it. For example, I have two L6-30R outlets wired up for my home theater, here's what those look like:

WBP_IG2620_PRODIMAGE_515.png (53.69 KiB) Viewed 651 times

This is how I have two 240VAC 30 amp outlets in my room

Dryer plugs are different of course, and I know our electric oven and central HVAC units are hardwired in. So specific applications are handled differently. I also forgot to mention another thing that's typically 240VAC here are welders too.

And let's not even touch on 3-phase.

Now I'm curious about the high voltage… What specs are there? Here about half the country is on 10 kV (the original spec from 1929) and the other half has been upgraded to 20 kV (which started being rolled out in the 90s) but the poles are identical. I think it's because they've engineered it so the insulators stand off the full phase-phase voltage on the 10-kV system, but they're also good for the phase-to-ground voltage on the 20-kV system, which is 20/sqrt(3) kV (about 12?).

I don't have an exact answer for that, but here's an image from a quick Google search that might help explain, since I know it varies and changes from location to location:

[PluMGMK]

Thanks!

Ah yes, 240 V AC, 30 amps. That's basically what I charge my car with! You can get a faster charge with three phases, since the phase-to-phase voltage is 400 V, which matches the EV battery, but it turns out my car is only wired for single-phase charging

I see, it's 13 kV there. But I presume it varies across the country? I know in the UK (including Northern Ireland) they use 11 kV, whereas here as I said we use a mix of 10 and 20 kV. The higher transmission voltage grades here are 38 kV, 110 kV (both in place since 1929), 220 kV (introduced in the 60s) and 400 kV as shown there. Our 400 kV network basically consists of two overhead lines that were built in the 80s, despite all the growth that has happened since then They're finally planning to build more, most of which will be underground. The proposed overhead ones are being objected to at every turn…

[Reese Riverson]

Thanks!

Ah yes, 240 V AC, 30 amps. That's basically what I charge my car with! You can get a faster charge with three phases, since the phase-to-phase voltage is 400 V, which matches the EV battery, but it turns out my car is only wired for single-phase charging

I see, it's 13 kV there. But I presume it varies across the country? I know in the UK (including Northern Ireland) they use 11 kV, whereas here as I said we use a mix of 10 and 20 kV. The higher transmission voltage grades here are 38 kV, 110 kV (both in place since 1929), 220 kV (introduced in the 60s) and 400 kV as shown there. Our 400 kV network basically consists of two overhead lines that were built in the 80s, despite all the growth that has happened since then They're finally planning to build more, most of which will be underground. The proposed overhead ones are being objected to at every turn…

You're welcome!

Heh, well one 240VAC 30A circuit powers my 12,000 watt subwoofer amp and the other one drives another subwoofer amp that can do 4200 watts x 4. So yeah, it takes power to make power in the audio world too.

Around here, 3-phase is more used only in commercial or industrial businesses, plants and stuff with complex machinery. Otherwise everything's mostly single phase.

I know a few hundred kV can be used for the big long power line runs, but I do believe the 10 to 20kV range is for the smaller power lines that then get stepped down further. The biggest problem with above-ground power lines honestly is how our storms here can knock them down, or cause trees to fall on them. Or how ice storms can be pretty nasty on them too.

Do you guys deal with much in terms of thunderstorms causing damage or power outages?

[PluMGMK]

Yeah… It used to be that every time there was a lightning storm we'd have guys going up the pole out the back fixing the transformer, but thankfully they seem to have replaced it with a more robust one during the 2010s… And of course every time there's a strong storm, the map for tracking outages just lights up everywhere because you get stuff falling on lines everywhere That said, underground cable failures have been known to happen too, and they can be pretty epic! A few months ago there were traffic lights out all over Dublin city centre, and back in 2016 half of north Limerick was without power for a few hours because a cable failed at an old substation (which they're only now getting around to retiring ).

[Reese Riverson]

What's the longest time you've been without power from storms?

Here in the US, our storms can get pretty nasty, since we can get more tornadoes and very strong severe storms more frequently than most other countries... yeah we're cursed.

While generally our power may act up during storms, the only long-term power outage we've had was one instance in the recent years where one storm system knocked down so many powerlines across multiple states and caused us to be without power for 10+ hours. That night I couldn't sleep, no AC, no fan... I went into work anyway 'cause there was power, but the moment power was restored at home, I left work early to take a nice long nap.

It is crazy to think about though, the power of lightning up against the electrical grid too. Or even if it gets your electronics... those surge protectors just can't hold up to the power of lightning... I mean we don't have a time machine built out of a Delorean to take the 1.21 Gigawatts needed...

[PluMGMK]

Oh, don't get me started on EMPs… There's conflicting opinions out there about how catastrophic a "Carrington-style" solar event would be for power systems worldwide… For example (one of the less worrying ones):

It's never been more than a few hours I don't think… Maybe five hours at most? We're lucky though, there are people in more remote locations who can be stuck for several days

A few weeks ago actually, I came home one Friday to find the power off, and apparently it had been off for several hours, and then it happened to come back on. But the pubs downtown were stuck for a few more hours. They seemed to have to repair each transformer in turn I had noticed back in 2021 that there was a pole some distance down the road where two 10-kV conductors were tied together, but the thread they were tied with seemed to be dangling in the wind. I said to myself, one day, that's gonna cause some mayhem… And since that outage a few weeks ago, I've noticed it's finally no longer dangling. So my conjecture is, it finally came apart, and resulted in a cascade of trips that took down the whole town. When they sorted it out, they made sure to do a better job of retying the conductors

[Hunchman801]

Very instructive video, I didn't know much about the electric grid in general and it feels a lot clearer now! That part about transformer saturation generating first-order harmonics was particularly interesting.

[Reese Riverson]

That is a very instructive video, I knew (more or less) how transformers worked, but I never dove deep into how solar flares/storms can effect them. It makes perfect since due to the nature of how transformers work.

Especially since transformers are practically used everywhere, not only just in the power grid but in a lot of electronics have used them for a very long time. Of course now days you see more usage of switch mode power supplies than the traditional power transformer to drop or raise voltages in electronics. Which not only helps with multi-voltage compatibility between countries but also in terms of efficiency.

I love how the topic originally started from a blender to 240VAC vs 120VAC and it getting to this point.

[PluMGMK]

Another really interesting electicity video from AlphaPhoenix:

It's all about how changes in voltage (and hence current) propagate through a circuit when it's first turned on

[Hunchman801]

Very interesting indeed, thanks for sharing! I must admit I had no idea what to answer at the beginning of the video, or at least until the water model was presented.

[PluMGMK]

The International Thermonuclear Experimental Reactor is apparently turning into the "most delayed and cost-inflated science project in history" https://www.theguardian.com/technology/ ... ig-trouble

Can't say I'm surprised, but it makes me nostalgic for my childhood when I first heard about it and found it exciting. I think I even hoped to work on nuclear fusion myself someday