Через тернии - к МКС

После успешного запуска в космос Многофункциональный лабораторный модуль «Наука» столкнулся с рядом проблем на пути к Международной космической станции. Сейчас он в автономном режиме успешно приближается к МКС, но его операторам удаленно пришлось решить ряд проблем. Попробуем сделать полный обзор непростого путешествия двадцатитонной «Науки» на низкой околоземной орбите.
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Why I support private spaceflight over, say, charitable giving by sportspeople

Unchecked capitalism is rapidly destroying the climate and most of the life on the planet. The Earth will be fine -- it's survived at least half a dozen mass extinctions before. But we might not.

We face a choice of 2 options:

• End capitalism, free markets, consumerism, globalism, and democracy. Move into a period of degrowth, massive population shrinkage, switch to green technologies, a low-power way of life for the remaining population: no international travel, no flying, no cars, etc.

This is probably the best way but it's extremely hard, nobody really knows how to do it, and there are a vast number of extremely powerful entrenched entities implacable opposed to it.

• Or, embrace growth and expansion, in which case there is only one place to go: move industry and power generation off the Earth and into space. Meantime, switch to greener tech here, such as mass solar power generation, electric cars, telecommuting, etc.

To do option 2, we need cheap, accessible space transport. Governments only did it in the 1960s to show off, and once the race was won, they stopped trying. They did it with extremely expensive, disposable vehicles, and as soon as their flags were planted, they stopped doing the hard stuff.

Some will now exclaim "but the ISS!" The ISS is about 220 miles, 350km, above us. You could bicycle that in a couple of days and drive it in an afternoon. No human has been further from the earth than that in about half a century, and there is no prospect of any government doing that very soon. Only Russia and China can currently do it; the American government gave up on it with the end of the Space Shuttle programme.

But SpaceX has done it repeatedly in the last year.

Yes, billionaires are going to space (or at least out of the atmosphere). Because only the biggest wealthiest companies can afford to do it. Because it costs billions, so only billionaires can afford it.

Yes, arguably, we shouldn't have private citizens who can afford their own space programmes. Our governments ought to be doing it, and they ought to be taxing those people to pay for it as well as for free healthcare and education and much more.

But they aren't.

So be glad that somebody is.

It doesn't matter why. What matters is that if the economy continues to grow on Earth and only on Earth it will kill all of us. There is only one place else it can grow, and that is space, where there is no air or water to pollute, no life to exterminate.

We need to embrace and support SpaceX and Virgin Galactic and Blue Origin. They are, for venal reasons, the trailbreakers of literally and precisely the only place we have to go.

The human race needs cheap spaceflight. We need solar power satellites. We need cheap lunar helium for fusion reactors.

It is by far the easiest path out of the mess we're in.

Yes, these early efforts are a bit poor. They are short hops, barely out of the atmosphere, not really into space at all and only just out of the atmosphere. They fall straight back.

But look at the context here. SpaceX nearly screwed the pooch. Falcon-1 launches #1, #2 & #3 all went wrong and were aborted, destroying their science payloads. Only the 4th worked – and delivered a bunch of scrap iron to LEO.

So many companies/efforts have tried and failed: Xcor, Armadillo Aerospace, HOTOL, Planetary Resources, Deep Space Industries...

This stuff is hard. Spaceplanes are hard. Launching from a plane is hard. Landing rockets is hard: no superpower ever managed it, because governments aren't much worried about cost.

No, Virgin "Galactic" aren't going into orbit with their current tech. Blue Origin are planning to, although they can't yet. But they got humans out of the atmosphere and back safely and that's a big deal. Only a handful of major nations ever did that before, and just 3 private companies have ever managed in history.

But the Wright Brothers only flew less than the wingspan of a 747 first time. They only managed 26 seconds and 846 feet. Not so impressive. But look what it eventually led to.

I used to live within walking distance of arguably the first public railway in the world. It was horse-drawn, and it was replaced by a canal -- arguably a step backwards.

But still, it was an important forerunner, and today a tramline I used to use a lot runs on that track. It wasn't a big deal in itself but my points are that what it led to was hugely important, and it's still around in some form.
Yes, the first efforts at anything are a usually rubbish compared to what comes later. But SpaceX set a benchmark and now others are striving towards that, and that IMHO is wonderful stuff.

Fun with Czech! [cont. from p.94] #projectPrague

Yesterday's Czech lesson was in the Locative case.

Locative, lokál, the declension for the state of being in a location. Used only after v (in), na (on or to), po (past, after, on, to, for, by – yes, all of them), při (by, nearby, with) & o (about, with). Although s is normally "with". Except if the word starts with a vowel, then it's se, although that normally marks a reflexive verb. Lots of verbs are reflexive.

The locative is, naturally, different for all four genders, and in the plural, and there are different endings depending on the final letter, or possible the penultimate letter, or possibly both, or you might drop the penultimate vowel, and then you might change the last letter.

*Brief pause for broken weeping*

One of the problems with learning Czech is that Czech people only do very basic grammar at school, so unless they have special training, they don't know how it works -- they just do these many incredibly complex convolutions, like declensions on multiple different plurals of irregular nouns in a hierarchical gender system, without thinking.

Which means that, because they don't know they are doing it, they can't not do it in order to, say, make life easier for a beginner. They can't stop doing something they're not aware of doing, nor can they explain it.
Many years ago my then-lodger Ulrike asked me what the difference between "who" and "whom" was, & I had to think hard to answer.

But I could, and it maps easily onto one structure of her native German, so from then on she used them perfectly – better than a native. We English-speakers only have he/him, she/her etc. and it only applies to pronouns, not to normal nouns or to possessives.

Czech has cases for:

  1. the thing doing the verb

  2. the thing being owned (also, all plurals >=5)

  3. the thing being given something

  4. the thing the verb is being done to

  5. the thing being summoned or identified

  6. the place the thing is in, or on, near, past, close to, with or about

  7. the thing being used for something or with something else

Yes, they must be in that order. People don't know the names, only the number. I use the mnemonic "No Good Driver Arrives Very Late & Intoxicated" to remember the names (in English/Latin).

Czechs use a system of little questions to work out which they're using:

  1. pád (Nominative) - Kdo? Co? [Who? What?]

  2. pád (Genitive) - Bez koho? Bez čeho? [Without whom? Without what?]

  3. pád (Dative) - Ke komu? K čemu? [To whom? To what?]

  4. pád (Accusative) - Vidím koho? Vidím co? [I see whom? I see what?]

  5. pád (Vocative) - Oslovujeme, voláme [Who! What! (calling or addressing someone/something)]

  6. pád (Locative) - O kom? O čem? [About whom? About what?]

  7. pád (Instrumental) - S kým? S čím? [With whom? With what?]

These help me not one whit. Not even slightly. None of them "sound right" to me.

The saintly Jana has memorized all the names for the cases so she can tell me which word is in which case when I ask. I can hear her quickly asking herself "kdo? bez koho? ke komu? vidím koho?" Then she goes "it's in accusative."
All these use-cases overlap. They apply to all nouns, to names, to posessives and to pronouns, are different for number (of which there are four: ordinary singular, plural singular, two to four, and five and higher), and are different for all four genders (and of course there are at least two to four patterns per gender plus exceptions).

Some nouns, for instance, have the feminine ending but are masculine, which means in some declensions they take the feminine forms, but not always. I think. For these nouns there's a special extra feminine ending bolted on (-kyne) to tell you that that form is really feminine.

The declensions for case #4, the most common – no, of course they're not in frequency order, that would be way too easy – make many masculine nouns (e.g. names) in the accusative take the same ending as feminine nouns in nominative. The endings for case #6 sometimes are pronounced the same as the different endings for case #2. The endings for nouns in case #5 closely resemble the endings for adjectives in case #4. And so on.

Vowels are closely rationed in Czech, you see. There's a national shortage. There's no easy way to distinguish "bull" from "bool", or "hut" from "hoot", or "bat" from "bart". So endings get endlessly recycled because there just aren't enough vowel sounds to give every case in every gender a unique ending.

I am slowly compiling tables of declensions and endings in a series of spreadsheets. If I can find a way to export these to LJ simple HTML, I'll post them on this blog.

The wonders of masala chai. (#projectPrague blog post)

Sometimes I get very annoyed with Past Liam.

I had two favourite Asian-foods shops in Brno. I looked up a few here, and in three-and-a-bit years in Prague, I never visited either.

Well, I've finally got around to it.

A couple of weeks ago, I found Orient Food in Holešovice. I spent about £60 in one go and staggered out with all I could carry. It's a good thing I didn't make it there with Ada a month ago, on my previous attempt to visit the place. She was on foot, which means progress was slow and inefficient at best. (Although she did great and was a little star – we went all the way into the city centre, to I P Pavlova (named after the great Dr Pavlov, who I am sure would be delighted at how a billion humans now jump and reach for their pockets at a mere hint of vibration). Foreigners affectionately call the station "I P Freely". That time, we went to the Candy Store where I stocked up on Marmite, crisps, biscuits and beer. Especially custard creams, which Ada picked for me and put in the basket. She gamely tried to carry it, but it was rather big for her.

(She put quite a lot of things in the basket, in fact – she very much enjoys putting things in other things. Today, while we were Skyping with her grandma, she raided the kitchen vegetable drawer, found a bag of onions, and after playing with them in the kitchen, she brought the bag into the living room, and unpacked the onions onto the sofa. And then back into the bag. And then out onto the sofa again. Then back into the bag. Then she gave her mum an onion. Her mummy told her to give daddy an onion too... so she took mummy's onion back and handed it to me.

I spent some time sweeping up onion skin this evening.)

Anyway. Back to the Oriental Potraviny. This time, it was more like a spicy orgy to make a Fremen sietch proud. Biriani paste and mix, plantain chips, frozen parathas, Bombay mix, some Tetley masala chai tea-bags, and more. I have been sadly missing a lot of my favourite spicy foodstuffs. ednun and I made quite a few shopping trips for such things in the Before Time.

I never knew Tetley's made masala teabags! The box proudly proclaims that Tetley's is now a Tata company. Tata, if you don't know the name, is a Mumbai zaibatsu who make everything from coffee to cars. I only knew the tea from my beloved and much-missed Sri Lankan restaurants of Colliers Wood. For tea, I especially recommend the Apollo Banana Leaf. (Prague's only Sri Lankan has closed down, and I am dismayed.)

Turns out, it's great. Being the real Indian deal and not some watered-down British version for feeble white people, it has a strong punch of both spice and tea. Wonderful morning pick-me-up.

Well, today, I visited the second such grocery store on my list – and discovered it was within walking distance of my old flat on Charles Square. How did I not know that? Swagat do both retail and wholesale, so although smaller, there's a quite different selection, including multiple blends of masala tea at 25% discount. I was recommended Wagh Bakri and I bought a tub of leaf tea.

And lo, I now know the recipe for masala tea! Well, the ingredients, anyway. I don't recommend making your own; I have no idea about the quantities.

  • Tea (Camillia sinensis) flavoured with:

  • Cardamom (Elletaria cardamomum Maton)

  • Clove (Syzygium aromaticum)

  • Black pepper (Piper nigrum L.)

  • Cinnamon (Cinnamomum verum)

  • Ginger (Zingiber officinale Roscoe)

  • Nutmeg (Myristica fragrans)

  • Long Pepper (Piper longicum)

Yes, they helpfully included all the Latin names. I have, however, fixed the spelling of a couple.

I will report back once I have tried it, but if you can, seek it out. If you've had coffee-shop chai, this will be a revelation. The real deal is a far cry from the weak Western version. It mirrors an experience I had in Tooting some years back. I visited a newly-opened Indian vegetarian restaurant, Saravana Bhavan, with Ednun, freshly back from a work trip to Gurgaom. When I led him in, he clutched my guiding elbow excitedly and told me that if the smells and the sounds were anything to go by, this was the real thing and the food would be amazing. Well, it was good, but not amazing.

I recounted this tale over a vindaloo to the late and very much missed nesacat, who told me that what I had to do was to go back there, ask for the manager, and tell him that I didn't want the food for British customers, I wanted the proper stuff that they'd serve to Indian customers.

Well, I went again, with Eddie again, and feorag, charlies_diary and pndc if I remember correctly, and although embarrassed, I did as Nesa had told me. The manager was quite indignant at the suggestion, and informed me that all customers got the same food prepared the same way...

... But this time, the food was excellent.

By a happy coincidence, just by the hotel that my employers put us in when we're in Brussels for the FOSDEM conference is the Belgian branch of Saravanaa Bhavan. It usually closes just about the time I arrive (after the cheap evening Ryanair flight from Prague), but last year, I hot-footed it straight from the airport to the restaurant and just got in in time to be served... and went again on my way to the airport on the way home, too.

As a wise man once wrote:
In this time, the most precious substance in the universe is the spice Melange. The spice extends life. The spice expands consciousness.
"Melange" is of course the French for a mixture. In other words, variety is the spice of life...

Think things can only get better next year? Think again.

Seen the Boston Dynamics dancing robots?

It's not CGI. This is CGI:

The dancing ones are, regrettably, real.

The question is: once they take all the terrible jobs in mail-order vendors' warehouses, and in Asian sweatshops, away, what will those people do?

Apart from die in the hundreds of millions due to climate change, of course.

I do find it bleakly amusing that as NYE approaches, people are digging up their old tweets:


December 2016: Thank god this terrible year is over.
December 2017: Thank god this terrible year is over.
December 2018: Thank god this terrible year is over.
December 2019: Thank god this terrible decade is o

We screwed the pooch. It is going to keep getting worse. The climate is destabilised. The world governments agreed in 2015 that we had a margin of 1.5º to fix things. Well, 1.2º of that is gone now.

Stuff is going to get weirder and less predictable from now on. Unseasonal heat and freezes. Hurricanes, monsoons, droughts, dust-storms, etc., where they don't normally happen, or disproportionately many of unusual force.

Massively hot summers in regions where the crops can't take it, but we won't be able to grow crops that can take it, because they'll be coupled with massively cold winters like we've not seen for centuries. Forested regions burning, even in relatively moist areas. Where I am, with woodland about 50 metres away, the intensely-managed forests are full of dead trees, killed by bark-boring beetles or the fungi they carry -- but that's probably because the trees were weakened by unusual weather. Some trees are standing, marked in fluorescent paint, but there are big heaps of logs everywhere too. The woods look superficially healthy, but they're not.

Everyone noticed that you don't get so many insects splattering on your visor any more, even in high summer? That's because about 85% of the world's insects have died since the start of the 20th century.

All the surviving forests are falling silent:

Because all the wild birds are starving to death:

60% of wild vertebrates have died out since 1970:

All wild animals on the planet now comprise about 4% of the total:

The rest are farm animals.

FTAOD I do intend to sound panicked, and to make anyone reading this feel the same. Brexit doesn't really matter. All that argument over fish? Irrelevant really as they're plummeting worldwide:

The 3 photos in this academic paper show the collapse since 1957 well enough that you don't need to read it:

Shorter version, more pics:

All that's left are tiddlers.

We are forcing fish to breed smaller and younger because we kill all the big ones.

We kill the small ones too but then throw the dead bodies back in.

Brace yourselves. 2021 will probably be worse than 2020, and 2022 will be worse than 2021.

Cooking made easy: I reckon the world needs more accessible, easy instruction in cooking

There used to be a really great late-night cooking show on British TV, at about 3 or 4 in the morning, called "Get Stuffed". http://getstuffed.info/dir/
It was all a cookery program for beginners should be. It should come back, and everyone who aspires to teach the masses of hoi polloi how to cook _needs_ to see it. A bunch of 'em are on Youtube.

The episodes were about 10min long. That's enough. Give me a recipe that takes 2h to prepare and I am not going to do it twice, because I like food that takes about as long or less to prepare as it does to eat. That is my line in the sand.

They tended to include a single-digit number of ingredients. This is good. Frankly, if it's fancy and needs 20 or 30 ingredients and multiple prep stages, I'm probably not going to bother. I can pay someone to cook fancy stuff in a restaurant. I'm not going to waste time and money fscking it up at home.

I can cook. I am not great, and I mostly don't do fancy stuff. I can't do anything with any form of meat and I'm proud of that, because I haven't eaten any form of dead animal since I was about 14 and I do not intend to start. So, any cooking show/book that is mostly dead-animal based, I won't watch/read/buy.
In my not-even-remotely-fucking-humble opinion, it's like this: a competent artist can create art from whatever materials they're given. Give them a sheet of A4 and a blue biro, and they can still draw a wonderful picture.

So, IDGAF what any cannibalistic bastards _like_ to eat. If someone's any bloody good in a kitchen, they should be able to create interesting food out of plants and dairy. Sod the dead flesh -- keep that to a minority of the time. I am not saying ban it, I am saying well under half. 1/3 vegetarian, 1/3 vegan, 1/3 meat is a good ratio.

Yes, it's sanctimonious, and yes, I am. I judge every meat-eating bastard and I find them wanting.

Short, quick, simple, easy. Amounts should be approximations and not tied to any units system, because they don't translate. Tell people what a bit more or less will do. Detail substitutions that will work. Tools should be simple stuff -- it was a revelation to me when I used to go to the Sci-Fi Weekender events and stay in a holiday camp. The kitchens have stuff I'd _never_ use, like potato mashers & rolling pins, but lacked sharp knives. I had to try to coordinate a bunch of nerdy guys who didn't know how to fend for themselves, and I discovered that people didn't know what I consider basic stuff -- like, how to chop an onion, or how to cut up a tomato, or the fact that for most veg you don't need to peel them, just give 'em a bloody good scrub and cut out any nasty bits.

So, what I'm saying is, yes, you're right, there *is* a real need for basic public education in dead simple cookery, but I reckon a lot of people tackle it totally wrong.

A friend posted a year or so back that she was confused by healthy eating advice: there was so much of it and so much was contradictory. I was amazed. It's dead easy. Michael Pollan said it eloquently:

Eat less.
Only food.
Mostly plants.

That's it.

"Eat less."

We eat too much. Making stuff filling is a priority. Think about protein content. That means not meat and it means cheap. Any restaurant that serves me 3 artfully-arranged twigs next to 6 droplets of sauce is one that's going to get a blisteringly bad review from me. Fuck that. Entire series of Masterchef would benefit greatly from an AK-47, but failing that, I'd give 'em a budget of £5 per person and it has to feed someone who is coeliac and someone who is vegan. If your menu includes the word "jus" so help me it'll be the last word you fucking write.

"Only food."

That means, you start with elements. Ingredients, not a jar of sauce, not a can of stew, nothing frozen or whatever. Someone in the 19th century should instantly recognise it and know what to do with it.

"Mostly plants".

Self-explanatory. Meat as an occasional treat once a week or something, not as a basis. If you can't cook without meat, fish or anything containing them then you can't cook.

This is why I occasionally post my own "Chef de Bloke" cordon-blur recipes. Because I hope that they might help someone somewhere. Actually, I promised Jana's sister one in the summer, so it will have to be in basic English too. That will be an interesting challenge.


Unix is Unix is Unix

From a Hackernews comment on my previous post.

Unix is Unix is Unix. Compared to the diversity that is out there even now, and far more so, to that which was out there 25y ago, all Unixes are the same OS, yes.

They are all one because the differences between them are trivial compared to their similarities. It doesn't matter if the kernel is monolithic or modular, or if the filesystem is case-preserving but not case-sensitive (NT, macOS). These are hidden technical details.

But most people now have only seen Unix and nothing else, so they think that these trivial implementation details -- like what is the default shell, or where are libraries kept -- are important differences. They aren't. They're unimportant decorative details.

When I talk about diversity, let's talk about some real non-xNix OSes I have owned, used, and worked with.

Assumption: shells

Imagine an OS with no shell. No command line at all. Shells are not a given. The idea of typing commands in text at a keyboard, hitting Return to send it for evaluation, getting an answer back, and acting according to that: that is an assumption, and it is one that came from 1960s mainframes.

The slightly more subtle idea that your input is sent character by character, and changing those can interrupt this -- e.g. Ctrl+C to cancel -- that's an assumption, too. It's from 1970s minicomputers, and indeed, the modern version is from one specific company's range: the Digital Equipment Corporation PDP series. The "enhanced" keyboard layout? Not IBM: DEC. The 6-dot-3 then 8-dot-3 letter filename thing? DEC. Filename plus extension at all? DEC.

Alternatives: classic MacOS. Atari TOS/GEM. ETH Oberon. Apple NewtonOS. Psion EPOC16 and EPOC32.

Assumption: configuration held in text files

Config files are an assumption. I have used multiple OSes with no config files at all, anywhere. Not hidden: nonexistent. The idea of keeping config in the filesystem is an artifact of one design school.

Other alternatives to it have included:

- a single global database, part of the OS, not visible in the filesystem at all.

- multiple databases, implemented as different parts of the OS design. One inside the kernel, one inside the filesystem structures of the OS.

- per-app databases, managed by OS APIs. So you don't write files or choose a format: you call the OS and give it things to store, or ask it what's there.

The upshot of these latter two kinds of design is that you get facilities like connecting a storage medium to the computer, and all its programs and data are instantly accessible to the user -- in menus, as associations, whatever. And when you eject a medium, it all neatly disappears again, reverting to previous values where appropriate.

Best example: classic MacOS.

Assumption: there is a filesystem. This is an integrated indexing system that stores data in blocks of auxiliary storage, where they can be found by name, and the OS will read data from them into RAM.

Filesystems are an assumption. Hierarchical filesystems are a bigger one.


All data is in primary storage (IBM OS/400, AKA IBM i.)

Or, media can contain databases, managed by the OS but not accessible by name (Apple NewtonOS).

Or, the primary storage is objects in RAM, and saving to disk is accomplished by snap-shotting entire system state to auxiliary storage. (Example: Xerox Smalltalk.)

Or, the primary storage is lists of values in RAM, and as above, disks are mainly used for import/export and for holding state snapshots. (Example: Lisp machines.)

When you take a long view, in historical context -- not the narrow parochial one of the last decade or two -- then yes, these are all different implementations of near-identical Unix systems. You've seen one Unix, you've seen 'em all.

What we have today is a biculture: various flavours of Unix, and NT. That's it nothing else.

There used to be a verdant, rich forest here. Now, there is just a plantation, with fruit trees and pine trees. You're pointing at apple trees and pear trees and saying "look, they're different!" And at plums (and cherries and damsons and peaches) and oranges (and lemons and grapefruit and limes).

Well, yes they are, a little bit. But look deeper, and there are hard fruit, stone fruit, citrus fruit, nuts. But all deciduous broadleafed hardwoods.

There used to be creepers and vines and lianas and rattan, and grasses and orchids and bromeliads and ferns, and giant herbs, and little parasitic things, some with vast flowers, and mosses and lichens and liverworts.

There was a forest, and it's gone, and no, you cannot persuade me that a neat tidy little orchard with a handful of fruit trees is the same thing.


What is RNA anyway? And why is it so hard to protect yourself against viruses?

[Recycled mailing list post in case it's useful to anyone]

You've heard of DNA, right? DNA is the chemical that is the recording medium for your genetic code and the genetic code of all living organisms, right down to bacteria. You may have also heard it referred to as the "double helix".

Note the "living organisms" part. This is important.

DNA standard for De-oxy-ribose Nucleic Acid.

It is a chain of smaller molecules, called bases. There are 4 of these in most organisms, and their initials are C, G, T and A. A pairs to T, or T to A. G pairs with C, or C to G.

DNA is structured like a ladder: 2 long chains, that twist around each other. The twisting structure is why it's called a helix, and the fact that 2 chains twist around each other is why it's a double helix.

Think of a ladder. The chains are the vertical rails. The pairs of bases are the rungs.

Because in DNA, A only pairs with T, and G only pairs with C, if you split DNA down the middle, each side goes:


or something like that.

Given the way that bases match up, you can reconstruct the other half:


This is a kind of error-checking, and that's why organisms use DNA for long-term storage.  Either half can be used to reconstruct the other.

When a cell divides, an enzyme comes along, splits the ladder in half down the middle like a zip, and then another enzyme reconstructs each side. Result, 2 matching copies, then the cell divides and each daughter cell gets a copy of their own.

To get at the info stored in DNA, an enzyme goes down the ladder looking for a marker for the bit it needs right now, which might for example say AAATTTAAATTT... that means "start here". Another bit later on says GGGCCCGGGCCC, meaning "stop here."  Then the enzype unzips the DNA after AAATTTAAATTT bit and makes a working copy, going along until it gets to GGGCCCGGGCCC then it stops.

The working copy only has 1 strand. It's half the ladder. It is not de-oxygenated. It is just RNA: Ribose Nucleir Acid.

It's for short-term working use, not long-term storage, because there is no error correction. No paired strand. So it's easier and quicker to read -- no unzipping or zipping required -- but it's prone to errors.

Right. That's DNA and RNA. A ladder structure (DNA, think "D for double"), and a working temporary copy, just reduced to half of it (think R for reduced).

Like I said, all living organisms use DNA. They have at least one strand of DNA, and encoded onto it are their genes, which tell them how to grow, how to make their special unique proteins, and so on. The genes are the constriction and operation manual for a cell.

How do you know if a cell is living? Well all living things do a bunch of stuff. They grow and move (even if just by growing, like most plants). They breathe: take gases in and emit different gases. They eat. They excrete the waste from the stuff they eat. They reproduce. They are irritable, that is, they respond to stimuli.

If it does all those -- grow, move, eat, breathe, pee and/or poop, respond and reproduce -- then it's alive.

Viruses are not alive.

Viruses are parasitic genes. They don't breathe or eat or reproduce. They float around, and then if they bump into the right kind of host cell, they get absorbed into it. Most of them have special signalling chemicals on the outside that tell the right kind of host cell "absorb me".

One they are inside, they split open and their genetic payload spills out. Then the host cell reads those genes and does what they say. The genes instruct the host cell to make copies of the virus. In most cases, the host cell is taken over completely, makes hundreds or thousands of copies of the virus until it bursts open and dies, scattering those thousands of baby viruses to infect other cells.

Repeat that enough and the host organism starts spraying viruses around in its spittle or in its pee or poop or sexual juices or whatever. Cold viruses make the lining of your nose and throat itchy so you cough and sneeze, spraying snot full of viruses everywhere. Someone else breathes them in, or swallows them, and they get infected.

The AIDS virus gets into your spunk or vaginal mucus and so it gets right onto the sexual or rectal membranes, invades those cells and starts getting copied again.

Viruses can't even reproduce themselves. They need to get the host's cells to do that for them.

So you can't kill them, because they aren't alive. They don't eat or breathe. You can extract them from someone's blood or snot or whatever, freeze them, and thaw them out years later and they become infective again.

But they mostly do have a complex capsule made of fats and proteins, protecting their genes. Damage or destroy that coat and they can't get into your cells and they are inactivated. They can't harm you any more. Soap does this quite nicely.

Complex animals, like us, have special immune systems that literally learn new threats and can then target them. So you could take just the capsules of viruses, with no genes in, or even a part of the capsule, like the protein spikes, and inject them into an animal's bloodstream, and its immune system goes "hey, that's not part of me, that's alien! Attack! Destroy! Exterminate!" And the immune system remembers this.

So, squirt a bit of the virus capsule into someone, they maybe get a mild fever, but they are now protected from the virus in future. When the real thing comes alone, with that matching capsule, the fore-warned immune system jumps on the invading virus and destroys it and you don't get sick.

Since viruses aren't alive and don't reproduce themselves, they only need a very small simple set of genes. A tiny, stripped-down, lightweight set.

And it's to their advantage to keep changing, so an organism that's seen last year's version with its distinctive capsule with a coat of protein spikes won't recognise this year's protein coat... and the new modified virus gets in, infects the host, gets into its cells and forces  them to start making millions of copies.

An error in copying DNA is called a mutation.

You are complex. You do not want errors in your genes. That would be bad. An error in your genes could give you cystic fibrosis, or muscular dystrophy, or sickle-cell anæmia, or hæmophilia, or a thousand other diseases, and if you don't get it you could pass it on to your children. As a complex organism with hundreds of thousands of genes, you do not want mutations. You just want a mixture of healthy genes, from other humans.

So you have error-checking and correction in your genes. They are recorded in double-stranded DNA for safety.

Viruses are not complex. They are very simple. Mutations are good for them. They don't have a metabolism to go wrong. Mutations help them. Random mutations might give them slightly different capsules from their ancestors, so they can infect hosts that have met their ancestors and are immune to them.

So some, but not all, viruses have switched from using double-stranded DNA to using single-stranded RNA instead. It's much more error-prone because there's no error-checking, but if you are an infective bunch of genes, that doesn't matter. So long as the slightly-mistaken copy of you is good enough to make other cells replicate it and make working copies, that's all it needs.

So transcription errors are very bad for you, but good for viruses that just want to infect you and get copied by your cells so they can infect other complex organisms with all sorts of lovely thick gooey sticky messy body fluids to carry other viruses around in, protecting them, keeping them nice and wet and protected until they can get into a new host and infect it.

And the circle of life continues. Hasa Diga Eebowai!

Nobody really knows where viruses came from. Some are super-simple. Some plant viruses are just little chains of DNA or RNA floating around unprotected, but then, plants don't have much of an immune system.

Some animal viruses are huge and complex. Some bacterial viruses are also super complex, like syringes with legs that are triggered by just the right sort of bacterial cell wall, and actively inject their genetic payload into the bacteria.

Bacteria are single cells, so each is very complicated because it has to do everything: move and eat and excrete and copy itself. They have genes too, in a single ring of DNA. No fancy multiple bundles like we have.

Bacteria have sex, too. They pinch off smaller rings of DNA and swap them. These are called plasmids. They are the way bacteria communicate and exchange genes.

It's possible some of those plasmids went rogue somehow and started making copies of themselves and spreading from cell to cell. That might be where viruses came from.

Multicellular animals and plants are far more complicated. Some of their cells can't survive alone and only live with the help of other, specialist cells.
Some animals and plants are parasites and live inside other animals and plants. If you live inside something else, you can become simpler -- you may not need to eat, move around, protect yourself etc. Your host does that. All you really need to do is steal food from its bloodstream or sap, and have sex so you can make copies of yourself.
Some parasites have become very tiny and simple. They exist just as bundles or threads of a few cells, able only to absorb food, make sperm or eggs, and those sperm and eggs to fuse and make new threads. They get passed on to their hosts' babies.
Well, maybe some of them went super-extreme with simplification and stopped the actual "living" part, and got stripped down just to their genes and a protective capsule.

Or maybe both. Maybe multiple times. It's hard to tell.