Pixophir

Now we're getting personal and reverting to common arguments of type "not even wrong". I've posted the data. I run an off grid house soon. And I am just one of many. In contrary. Renewable energy production overtook thermal production in many countries. Some rely totally on the former. And, btw.(edit), had Europe put more effort in rolling out renewables, they wouldn't have that many problems now because of the horrible circumstances. Countries with high renewable share are better off. France's plans are changing, apparently people are understanding that relying on nuclear put them on wrong track. Though they also speak of new coal plants, which is irresponsible under the global threat of climate change. They are importing energy because they have unexplained stress corrosion and no maintenance people and material to repair it. The reactors are shut down because they are unsafe. The nuclear lobby's plan didn't work out. Lot of rotten fruit :-)

All these questions have relatively simple answers. The last one, in case people haven't heard, France has massive problems with partly unexplained stress corrosion in more than half of their reactors. Since the country runs mostly on nuclear, they must import energy. Replacement of solar panels is just trivial and can be done by everyone. They should be recycled, that's an emerging industry. Replacement and recycling of nuclear material (and that includes fusion reactors of the Tokamak type like ITER) is an unsolved, even unsolvable problem. But there's a misunderstanding here: A solar installation doesn't need much ado in that time. Otoh, no thermal power plant runs 30 years without massive maintenance, a constant stream of parts and fuel. Thermal power have long down-times, sometimes years.

Solar panels are mass products. Like gummy bears. Do you like gummy bears ? I do :-) Imagine the following: from 28 ordered RTGs 3 arrive broken. You see the pallets on the truck and think "Idiots". You call the store, say, guys, someone broke 3 of the RTGs, looks like a forklift race. They say: again ? Oh we're as sorry as possible. We'll have a word with the shipping company. Will send a replacement the next days, just give the broken ones to the recycling, will you ? Now, isn't that easy peasy ? (Happened to me. Replace RTG with solar panels)

I have. It is not magic. I'm sure you can find a DIY video on youtube. When done, show me how to do a nuclear reactor in the garage. You can choose the type and buy any special parts. But it must last 30 years only with occasional dusting and (I'm being sporty here) 25% loss of power output, ok ! No fuel change, no additional maintenance, I don't use fuel either and when properly grounded the rack aluminium won't flow away. 600W(peak) ~250 Euro (daily prices can vary). Well, ok, that can be 30kg ... needs a second hand or a solar powered electric sledge to schlepp on the roof. If nuclear gets a break even of ... a forget it. It'll never get a break even. Cost accumulates every second. Seriously, that must be calculated for an installation. It is longer than 2 years, but much shorter than the lifetime even without excess feed-in. Edit: btw., what was that about countries with renewables helping out nuclear driven countries because their reactors are out of service ?

No need to pray. Solar panels start at a bit above nominal, and go linearly down to between 80% and >90% output after 25-30 years, depending on technology. That means they loose 10%-20% in 30 years, just to avoid confusion. Please look it up. And yes, there are installations from the late 80s and early 90s for confirmation and technology has improved since then, with further steps under development. Won't comment on the sarcasm, but quite up-to-date because actually happening, what happens when the nuclear power plants in a country stand still ? Right they import renewables from the neighbours ;-)

These systems are standard on some types of small or light aircraft (Cirrus I think), offered as an extra in some others (small Cessnas), but not generally in use. In some countries (Germany for instance) they are required by law for light aircraft (<=450kg). They have saved a lot of unlucky or unwary pilots who flew in bad weather or didn't watch the fuel gauge, the two most frequent accident causes in light aviation.

Dear colleague, politics, agenda and general defamation aside, the power source for the roof top exists. It is called solar power and depending on the area it can easily supply a household with power including charging an electric car, and add excess to the grid, earning a buck or two. It doesn't power households for just a decade, rather 2-3. There are solutions to combine it with wind and water where applicable and wanted. In combination with a low energy house, well insulated and intelligently placed windows and ventilation system with heat exchanger, heat pump, living off-grid - for whatever reason or agenda, - has become trivial at not too high latitudes. Individual cases need calculation of course. In most countries it is an initial investment that pays off, sooner than later at current price hike rates. One needs a house with somewhat suitable roof or another area and/or can participate in neighbourhood projects. These solutions are often times subsidized. Some of it (the PV part, when not grid connected because regulations) can even be made DIY to a degree, because DC isn't rocket science.

Climate change is happening now. It cannot be stopped even if all emissions were reduced to zero immediately. It could have been kept in boundaries by rolling out renewable energies starting with the clear and precise warnings some 15 years ago, with less certainty much earlier. That didn't happen, and it isn't even happening now, quite the contrary actually. That leaves us somewhere on the pathways between 2° and 6° warming and up to 3 billion people falling out of the margins for human (or generally) habitability on the planet. The respective projections have not taken into account some positive feedbacks that are right now impossible to quantify with rigour. Nobody knows when and if fusion will be ready, it is probably a dead horse by then because too expensive and fuel shortage, a problem that has been hand waved away until now.

Outch, sad news.

Military can help there but it is not their primary purpose, which is called defence in most countries. There are military units that can help in the case of catastrophe, for instance clean up destruction of fire, flooding, earthquake, volcanic eruption, ... because any war is a destructive catastrophe and clean up help is needed, but civil protection plays the bigger part in most countries, and is also better connected then the military. Scientific help is more important for judging the various dangers connected with such events and give counsel on how and where to act to minimize effects on property and life. These are people from universities and research centres connected around the world as well as civil protection departments of governments at various levels. If additionally to civil protection, military units, when called to a scene, can be advised for instance to help collecting data on hazardous materials, or to find a way to cut off areas, when civil resources are bound elsewhere, for instance because fire and flooding struck at the same time. Edit: just realized I'm slightly off topic :-) Anyway, there's more than enough to do in civil applications and for spacey engineers (congratulations, @cubinator) on all levels. Combating (military wording :-)) climate change is the most pressing problem, and I believe all of the larger organisations have a foot in there, even if they also offer military products and services. I don't think it is difficult to find a job that fits the personal view.

Certainly, but they'd be on different trajectories, e.g. one on a Hohmann transfer, the other on a brachistochrone. Ignoring engineering challenges for the latter, just a hypothetical example. And not having done calculations. Of course there's always a point for two such given spaceships, where the first becomes uncatchable by the second, depending on orbits and technical data.

I clave a bowl of flied lice with vegetables downtown in the Chinese lestaulant. Thel we can sit by the seaside and watch the cals pass and people stlolling along the beach. Aftel dinnel I'll oldel me a cold beel and put on that deeply satisfied glin :-)

Yep, and iron airships between moon and planet. Could be a sign of advanced entertainment, and highly speculative of a civilization that has passed the crest of its development and is now on the downhill side, destroying one another. The "window of communication" (S. Lem) is closing and maybe a message sent now arrives over a pile of smouldering rubble. Seriously, here's the paper (open access): https://www.sciencedirect.com/science/article/pii/S0094576522002594?via%3Dihub There's nothing concrete in there but a lot of conditionals and suggestions of what could may be might be worth to risk an eye. For now, I think we can put our observation power to better use.

They're probably in their 1960's right now, drivng around in piles of chrome, listening to Beatles or Elvis on distorted AM frequencies ...

Nasa seeks proposals for the construction of a "starshade" that can help blending out a distant (tens of ly) star to enable upcoming earth based 30m telescopes with new adaptive optics to image close planets around the star. It is too early to rejoice, though, right now there's no idea how such a thing could be really constructed and brought into space. Hence the call for proposals. https://grabcad.com/challenges/nasa-challenge-ultralight-starshade-structural-design https://microdevices.jpl.nasa.gov/capabilities/optical-components/starshade/ There may even be a (currently hypothetical) chance to support an own 6m telescope in space with these shady doings. Resolution in combination with an E-ELT for instance would be ... would be ... really cool :-) https://www.jpl.nasa.gov/habex/mission/

Has simple roots from back in the day: it reduces memory usage and uses a very simple data structure (a stack) to represent all its operations. It also speeds operations up because there is no parsing of parentheses like in algebraic notation. There are just operations as they come. Which also puts more "load" on the operator, who has to sort their input prior to typing. https://www.hpmuseum.org/rpn.htm https://en.wikipedia.org/wiki/HP-65

Yeah, its a simplification and partly also a misunderstanding: pemdas are not rules, their are just a help for the untrained. Real world is ludicrously more complicated. Imagine they wouldn't get elementary school math right. I too think left-to-right is cultural bias. When looking at a properly written and well formed expression one does that sorting into patterns automatically, almost subconsciously, like one would try to understand a written clause or sentence. Of course it depends on the complexity, and there may be a limit for everyone, specifically when machines start to take over in data science or so. A long fraction bar, a function, an integral, a sum, these are all basic patterns that spring out, like punctuation in a well formed sentence. Sure one can obfuscate the meaning of anything, which can be fun like here. But in serious writing one would make the meaning clear. Look at the first two examples @RKunzewrote 2 posts above. Aren't they neat and clear and leave no question ?

@Dman979: I was curious and plugged 6/2*(1+2) in desmos and it has 9 as the result, just like wolfram alpha. One must press arrow right to get the cursor out of the denominator, else one types 6/(2*(1+2)), which is another expression. Try it out ;-)

That's wrong, there is no equivalence there. You would have to show that 6/2*3 = 6/(2*3). Good luck :--)

Exactly that because the fraction bar only spreads over the A, and if there was a multiplication sign between A and B. Because it equals to 1/3*2, which is 2/3. One can confuse that with 1/(3*2), which is 1/6. @Dman979 https://www.wolframalpha.com/input?i=6%2F2*(1%2B2)

@Vanamonde: I think pembas ist just nonsensical (Edit: ninja'd and clarified by @RKunze, and the list given in their post below is what I recall. But pemdas should really correct this on the entry page). Btw., for those who need more multitude, there's also bodmas, which puts division first :-) Looking in the first chapter of one of my math books (German) it starts with logic stuff (what's true and false), sets and operations on them, we get commutativity, associativity and distributivity and these are used to explain the rules of doing calculations with the numbers. That's the most basic I have here. I recall that last I saw an offspring dabbling with this they had parentheses, then mult/div, then add/sub. Exponents came later and slid in between parentheses and mult/div. What's important is that div is the inverse of mult, and sub the inverse of add. That makes them interchangeable in their "level", thus there can't be a precedence. The whole thing is this causes the ambiguity of the expression in the OP. I have actually never seen that before, but when searching I immediately found a vast base of such things in the social networks. It may also have such a wide spread because of social networks, which tend to share and multiply things like "look what I found", and when looking there actually nothing to see.

The majority is of the same opinion, but at least two math related guys disagree, specifically with m before d part. This is trivial, because m and d are interchangeable by the reciprocal. There goes m before d ... neither comes first.

Computer agreed, but as a math aficionado and never having heard of pemdas (doesn't it also say m before d ?) before (I know associativity, distributivity, commutativity, parentheses, exponents, mult and div together and add and sub together) I'd rather turn everything into multiplication to get rid of the ambiguity. That is 6*(1/2)*3 and the truth is revealed without parentheses because that can have any order :-) Tata ... Might be though that that was not the expression the author had in mind. You think that's cheating?

Yeah that's impossible in code (here C/C++) because depending on semantics and other things like what's x and y, type designators it is either a function declaration, a cast, an instance of an object with a variable or a function declaration with an object as parameter. If you don't believe me the latter search "most vexing parse" :-) Which, btw., was resolved by allowing different types of parentheses. But here we're not that complicated, we simply have constant values, a missing operator(*), and missing pair of parentheses. That's all :-)

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