Beamer

The highest known remanent magnetization (basically, the magnetic strength of a material once it's outside of any external magnetic field) is around 1.3 Tesla for a neodynium-iron-boron magnet. Materials have a magnetic saturation level, the highest saturation levels are just over 2 Tesla, but to reach this value it actually has to be inside a stronger magnetic field (typically the core of an electromagnet). Although advances in material science might increase this a little further, it won't be huge jumps. So you can forget about 1 kT, or even 10 Tesla for that matter. Note that a 1000 Tesla field will damage organisms and outright destroy electric circuitry, so the usefulness of magnetic fields of such magnitude tends to be limited to academic study. The highest practically useful magnetic fields go up to about 7 Tesla max in an MRI scanner, and up to 7.7 Tesla in the LHC. And you have to be very careful not to carry anything made of metal near those. The highest 'permanent' magnetic field created with electromagnets is around 100 Tesla (which is enough to create horrible shrieking sounds whenever it is turned on). These can run for only a very short duration, a few seconds at best. Higher magnitudes have been reached but only by using shaped explosives or similar destructive methods (like laser compression or magnetic compression), so these are very short lived by their very nature. This sort of thing is mostly used in fusion reactor research.

Basically, your estimation of rarity is incorrect (or incomplete if you prefer). It is not rare for binary stars to collide. In fact you could say they (or their stellar remnants) always collide - the only alternative is they get flung apart, in which case it's not a binary system anymore (I know, that's cheating a bit, but you get the point ). Of course it takes a lot of time, there are plenty of binary system where it won't happen for a longer time than the current age of the universe. The kind of collisions that are presumably extremely rare are the ones where 2 stars/remnants that weren't in orbit of each other collide (even in galactic mergers this is considered a rare event). This is simply because although stars are big, the empty space between them tends to be a lot bigger. The reason you've probably seen a lot about it in the news lately is because they think they detected exactly such an event recently, where 2 black holes pretty much had a high speed near head-on collision (they crashed into each other after only 1 pass, without a spiraling phase). See for example https://arstechnica.com/science/2022/11/strange-black-hole-merger-may-have-been-a-rare-random-encounter/

A rather amusing look into space elevators by an expert on the subject: https://www.scientificamerican.com/article/space-elevators-are-less-sci-fi-than-you-think/

From https://www.theguardian.com/science/2022/dec/05/are-we-alone-in-the-universe-work-begins-in-western-australia-on-worlds-most-powerful-radio-telescope Meta, Google, Apple and a number of TLAs are perking up. I wonder what sort of targeted ads you would get while wandering around on Mars. "Feel peckish? The nearest McDonalds is only 225,000,000.3 km (5,133 years, 5 months, 21 days, 18 hours and 5 minutes) from you!"

You're forgetting that the various member states also have their own space programs and industry (which don't just work for ESA). Furthermore, NYC needs a lesson in efficiency because that's so horribly excessive I can't image that not at least half of that goes in pockets that have nothing to do with education. It's really hard to compare the way the US government spends their money to that of most European countries. The vast differences in defense on the US side and public healthcare on the EU side alone make such a comparison look weird no matter which way you look at it. In the end a space program is an 'extra', something you do after all the necessities have been paid, and the USA and EU have very different ideas about what counts as necessities.

Education is typically a state matter in European countries, not a city matter, so it's hard to find a 'by city' table anywhere. You'd probably have to find a 'by school' table and tally it from there. Furthermore, education is a national matter, not a EU matter, so you'll have to go to the state website of each country separately to find their budgets, unless you can find some sort of 3rd party aggregator. Here's where I would find it for my country: https://www.cbs.nl/nl-nl/cijfers/detail/84122NED 20B on education. Most populous city is Amsterdam with 900K which is about 5% of the national population. Space on the other hand, at least when talking about ESA, is a EU matter, so things get complicated. 64% of the budget comes from direct contributions from member states, however something like 28% comes from the EU itself, which of course pays it with contributions from the member states to that institution. Here's some fancy pie charts of the various contributions that make up the ESA budget: https://www.esa.int/About_Us/Corporate_news/Funding I think the determination of how much each member state contributes, aside from economical position, depends a lot on where the work on the hardware is done. So not all that different from America's Pork Powered Rocket I guess, if it generates jobs or keeps existing industry afloat, countries are willing to make a bigger contribution. Edit: all numbers in Euros of course Edit 2: According to this table, government expenditure on just primary education institutions (including pre-primary which I think is 4-5 year olds) is 12.5B, which works out to 8.5K per child: https://www.cbs.nl/nl-nl/cijfers/detail/80393ned

Just over a week ago they announced an increase of 17% for the coming 3 years, compared to the 2019-2022 budget: https://spaceref.com/science-and-exploration/ministers-back-esas-bold-ambitions-for-space-with-a-record-17-budget-rise/

Woke up to it, been blaring along to the lyrics I barely understand all day, my neighbours probably think I am having some sort of episode.

Wiki has a helpful list. I like the Czech attitude, their space agency is just a department of their Ministry of Transport. Like, space, it's just another destination man. https://en.wikipedia.org/wiki/List_of_government_space_agencies I think you can pretty much follow the Pareto Principle there. 80% of the trash is from 20% of the countries who ever launched anything into orbit. French Guiana is part of France.

ArsTechnica did an enlightening story on the wormholes: https://arstechnica.com/science/2022/12/no-physicists-didnt-make-a-real-wormhole-what-they-did-was-still-pretty-cool/

What they actually did was create a quantum state that mimics the properties of a wormhole. No actual wormholes were involved. To me it sounds a lot like one of those "Look what we did, give us a grant! Blockchain! Metaverse! Crypto!" articles. As they described it: "a quantum system that exhibits key properties of a gravitational wormhole but was small enough to implement on existing quantum hardware." It goes beyond my knowledge of quantum computing to determine if it is actually some kind of breakthrough in that field but I'm pretty sure the assertion that "they created a wormhole" is just pertinently false. Edit: since CNN doesn't seem to link to the source, here's the abstract of the actual Nature article: https://www.nature.com/articles/s41586-022-05424-3

Sounds good to me, it should get us by until we find a Tetrahedral world that shouldn't exist. Not bad for a day's work. Of course the hard and time-consuming part is getting it past an international committee, which is probably why we have a definition that seemed barely sufficient half a century ago

Been playing some XCOM 2: War of the Chosen lately, not a new game, continuing a save game, classic difficulty, no mods. Just raided the first Chosen's stronghold in an absolutely brilliant fight, my squad of 6 wiped out a strong welcoming committee of 9 mobs in a single turn without any damage, it was one of those glorious moments. Made it out with 1 minor wounded and 5 tired but satisfied solders, 2 promotions including my first Colonel. I've been playing the UFO/X-COM/XCOM series since the Amiga days (1994), it's one of those games I always get back to.

Seems pretty comprehensive, although I'm missing fall-backs for binary star systems Anywhere you say "orbits a star" I would go for "... or the barycenter of multiple stars" or some such.

First time the Chinese Tiangong Space station has had a hand-over from one crew to the next, it is assumed that from this point forward it will remain permanently occupied. https://www.theregister.com/2022/11/29/china_tiangong_crewed_handover/ https://www.wsj.com/articles/chinas-latest-rocket-sends-new-crew-to-finish-tiangong-space-station-11669747788

According to some 'reputable' news sources, we already do!

I can't remember exactly the last time I saw snow. Living in The Netherlands which is at that point where winters get just cold enough to get a few weeks of ice and snow... or at least it used to when I was younger. I remember throwing snow balls as a kid, going to the (natural) ice rink with my parents, having a day off from school to go ice skating, not a chance of that these days. Amazing to think there are 25 year old people now who have never witnessed a Elfstedentocht...

Yep, that's what I get when posting at 4 AM Awesome image, don't think I had seen the colorized version before. I must admit I was slightly disappointed when it turned out not to be aliens... again

Not all that new, but off an on. Lately I've been doing a round of XCOM2 (sometimes you want to kill some LGM the old-fashioned way ), which drastically reduces the amount of time I spend posting in the "What did you do in KSP today?" thread, which in turn gives me more time to sleuth the science forums for interesting topics.

Well I guess I am a bigger proponent of rigorous definitions than most astronomers. I'm a database specialist by trade, a lot of my work revolves around trying to bring structure into badly indexed data. And that, my astronomer friends, is a BAD index But I suppose they don't worry about the fact that they have to revise the definition every X years or so, that's for people like me to fix afterwards. There's a clear natural index which flows from the orbital mechanics. Planets orbit stars, moons orbit planets, moon-moons orbit moons. If you want to add a mass limit on top of that, sure no problem, over X mass follow the above, under X mass call it a dwarf-something or make up names like 'comet' or 'asteroid' or 'ring system', those are just attributes of each specific body. But the (c) rule always seemed pointless and useless to me. It's a moment in time, maybe it hasn't had the time yet because it migrated orbits or is still young. And of course there's the Uranus/Pluto problem. What about Jupiter, aren't the trojan asteroids considered 'in the neighborhood'? Is that a rigorously defined volume in astronomy anyway? Worst of all it doesn't say anything about the body, it tells you something about its neighborhood, it's in the wrong table! And there are almost more exceptions to it than confirmations of it. No idea why that's there. As for (a), I'm not an expert in the lingo, perhaps they mean 'Sun' as in "central star of a solar system". Do astronomers refer to the Sun as 'Sol'? The fact that it's spelled with a capital makes me think they mean "our star" which is just a revision waiting to happen.

If they grew up there I would assume they would have evolved in a way to deal with it, and perhaps even take advantage of it. It would provide some interesting options for navigation. Imagine living on a world where you could determine your altitude simply by measuring the angle of the ground with the gravity-normal. Global navigation on Earth required the development of extremely accurate clocks as well as many observations of stars. On a Platonic solid you'd have a much easier job as there is the extra information of the angle between the horizon and the direction of gravity. On a sphere that angle is always 90 degrees, so it doesn't give you any information (other than that you are, in fact, on a sphere, dear flat-earthers ), but on a Tetrahedron it would tell you how far away you are from the center of one of the polygons.

If we ever encounter a planet in the shape of a Platonic solid I suspect it will quickly go the way of the dodo Pluto That quote is from a NASA site anyway, they tend to simplify stuff for the general public (makes sense of course, their target demographic is "The American tax payer" rather than "Professional Stargazers"). The literal quote from the IAU's resolution is thus: (1) A planet1 is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit. Source: https://www.iau.org/static/resolutions/Resolution_GA26-5-6.pdf So it looks like they accounted for SmartSes when it comes to (b) The more interesting part is (a) I think. I guess an exoplanet is not considered a planet but is a class by itself, which seems a bit heliocentric and silly to me. By 2006 we had found a good handful of them so it's not like they didn't know exoplanets existed.

Depending on who you ask, it may have happened one or multiple times during the Proterozoic eon. Not since the Precambrian no, but the first land life emerged well before that (In fact I think by now they've pushed it back to 2.7 billion years ago which would put it well into the Archean eon). Snowball Earth is a bit of a bad name, the important part about these periods is that enough potable water is locked in ice that there is no precipitation. That doesn't necessarily mean that the entire earth is covered in snow and ice. There may still be open stretches of ocean and land, as long as the temperature is low enough. If it happened again I think complex life would stand a pretty good chance. The oceans under the polar caps are full of life happy as pigs in mud. Thermal vents have complex life forms around them. Plant seeds and fungal spores might survive long periods of freezing. Hot water springs might even provide small biomes for fresh water aquatic life. I don't think we'd have to go back all the way to single cellular life after such a period, but your garden variety mammals would definitely be out of the picture for a while :s When it comes to human-like intelligent life though, who knows. I certainly believe we would try. We can create energy from the sun, wind, geothermal, plenty of energy to create our own biomes. Food would be an issue, it would all have to come from hydroponic gardens (lab grown meat?). If it happened 'right now' we'd be in trouble but 100 years, 200 years from now? I think it would still beat living on Mars To tie it all back to the original question, I think it would be unlikely for complex life to evolve and thrive on a desert planet. Once it's started on a planet to the extent it has on present day earth however, I can certainly see it surviving their planet turning into a desert, especially if it's the space-faring type of life from sci-fi books and movies rather than just microbes or 'cow and chicken'.

Titan has lakes, rivers and clouds, they're just not made of water but of methane. Although rain was not directly observed AFAIK, if there are clouds, rivers and lakes it stands to reason there's a rain cycle involved. On Titan, the 'ground' is mostly made of water ice, the methane cycle plays on top of that. Venus of course has clouds. It also has a rain cycle, although the general consensus is it never reaches the surface in liquid form. However since there have been suggestions about life in Venus' atmosphere I didn't want to outright group it with desert worlds. Its atmosphere is so dense and material-rich you could argue its a biome by itself where life could conceivably persist and perhaps even originate. But looking purely at the surface you could certainly argue its a desert world, it doesn't change the odds all that much The gas and ice giants are just nasty. As beautiful as Clarke could make it sound, I don't think there are ever stable enough conditions for life to get a foothold. It's not that the materials are not there, but its all so turbulent that if you were to 'inject' some form of life that could survive in the local conditions where you injected it, it wouldn't take more than a day for it to end up in conditions that would outright kill it.

But erosion doesn't limit itself to the top of mountains, quite the opposite in fact. The further you go down a slope the more water and debris from higher up will stream over it. It would just eat away at the slopes and the tops would collapse as the slopes became to steep to support their integrity. You would need some active process to 'top off' the mountains and slopes to combat this. On earth mountains form due to plate tectonics and volcanic activity, those processes require a molten core which would cause your body to become spherical. A totally rigid body would just wear down, it would have no active geological processes to keep its shape.