Seret

You know you can just change the batteries, right? The bottom part of the handle just pulls off.

Looking at the current programme it looks like the most it'll achieve is a few flights, but not enough to make it worthwhile developing. It needs to be either scrapped or rethought.

No, as far as I know there's nothing in the UK. There may have been something in the past, but there's certainly nothing now. Given that there is still a large state-owned broadcaster that can reach most of the population over various media I suspect the government didn't see a need for a parallel system.

What level of computer experience do they already have? What are your objectives for the hour? Things like Scratch should be appropriate for that age group, but get anything done an hour you'd need to provide quite a structured lesson. Programming isn't necessarily the best thing to try and tackle in a single hour though, other topics like online safety might be more practical.

Look, you made a dubious statement, got called on it and proved unable to back it up. You can interpret that as a personal slight, or you can realise that you're just being held to the same standards of proof as everybody else here. Up to you. This is an unhelpful comment, and beneath you lajoswinkler. Broad-brush ad hominems like this will just turn an interesting discussion into a childish argument. Regarding solar updraught towers the argument against them is purely economic. Some perfectly functional prototypes were built in Spain (IIRC?) and proved the concept. The problem is that the efficiency of regular PV has gone up and the cost has nosedived so that it's now much more cost effective to just spend the same money on a conventional PV farm.

The panels aren't, but the silicon industry uses all sorts of extremely nasty stuff during fabrication. They don't emit it deliberately, because to do so would be illegal and dangerous for their workers, not to mention expensive, but accidents do happen. That's all taken into account in lifecycle analysis, and PV does still come out having a substantial net benefit. It's difficult not to when they directly make a high-grade energy source like electricity using no fuel.

I think you may have misunderstood something your friend said. What's sitting on the ground doesn't effect the amount of energy the in the sun's rays. What it does effect is what happens to that energy after it reaches the ground. In the case of a flat white panel, a small amount is absorbed as heat and a large amount is reflected away. For a black panel a large amount is absorbed as heat and a small amount reflects away. For a PV cell a large amount is absorbed, some of that as heat and some is converted to electricity. A small amount reflects away. Due to the fact that some energy turns to electricity instead of heat a PV cell will heat up less than a flat panel of the same colour. The only time a PV panel will result in a net increase in absorbed heat is if it is substantially darker than the object it replaces. This is effectively a small change in the Earth's albedo. The albedo does directly affect radiative forcing, which is important in climate change,but the idea that emplacing solar panels would significantly affect radiative forcing to the degree where it would be a stronger signal than the carbon emissions avoided is the kind of claim that would definitely raise eyebrows and have most people coughing rude things under their breath. At the very least it falls into "extraordinary claims require extraordinary evidence" territory. Personally I think you either misconstrued what your friend was saying, or your friend was talking from a non-expert position. Being (a student?) at MIT hardly makes you infallible, especially when it comes to topics like renewables and climate change, where everybody seems to have a strong opinion whether they're well-educated on the facts or not.

I'm not a physicist, but I do remember reading it explicitly stated at some point that the nature of quantum entanglement doesn't allow information to pass between them at superluminal speeds.

I'd suggest actually doing a proper home energy audit. Get a plug-in meter and record what everything is actually using. Some things like refrigeration you'll want to leave plugged in for at least 24 hours and get an average reading, as they cycle. This will show you where the quick wins are. Things like phone chargers are actually pretty small fry, by all means unplug them when they're not in use, but it won't make a big difference. Anything using over about 5W on standby will show a net reduction is you switch it off for several hours a day, even if you're using a watt or two to automate the switching. For example things like this will switch off attached disk players/soundbars/hifis/whatever when you turn your TV off, this will turn off printers, speakers and monitors when you switch off your computer, and at the most basic segment timers can switch of batches of things overnight. When I did an audit I found my toaster (wtf?) was consuming about 15W continuously, meaning it used more power in a year of standby than it did making toast. There's really no good reason not to reduce your consumption IMO. I think the 20% figure mentioned above is easily achievable for anybody, but you need to get the data first to inform your decisions.

There's a place for both. Decentralised production avoids transmission losses, which can be substantial in some countries. Decentralisation is also a good idea if you've got high heat demands and want to locate CHP sources close to domestic areas. Large thermal plants may have good electrical efficiency, but they still blow between half and two thirds of the fuel's energy into the atmosphere as waste heat. Rubbish. Is your friend actually suggesting that we might at some point cover enough of the planet's surface with solar panels to significantly affect the albedo? I hope (since they're at MIT) that they've got some reliable studies to back that claim up with. What we should be doing albedo-wise is painting every roof in the world white. The overall effect would be slight, but it's so cheap it'd actually be quite cost-effective.

We know nuthin.

From my own personal experiences with journalists, I don't think it's malicious. I just think they genuinely don't understand about a lot of the stuff they report. The few people working in media with genuine science and engineering knowledge are often hamstrung by their editors.

Electricity demand is pretty steady over the working day. Output from any one particular solar array is basically a sine wave, but is also affected by the direction array the points. Those facing more easterly generate more in the morning and less later, and vice versa. Obviously real output is quite messy and not a nice curve. It's not a big problem as most solar is embedded and just shows up as a reduction in demand.

Of course, long pauses in the conversations could also account for the apparent silence.

The batteries would generally only be discharged for spikes in demand, which generally occur in the evening. You wouldn't be drawing from them in the wee hours, in fact it'd be more likely to be dumping excess power to make up what it has taken a few hours earlier. The idea is to do two things: Allow stable base load plants to handle pickup loads by decoupling production and supply. Provide a mechanism to smooth output from variable sources if required. Personally I'm sceptical how popular such schemes would be with consumers. Big industrial users are quite receptive to demand management, but individuals are funny about their cars. Same thing. It's trivial to assess risk when the unlikely event has already happened. Doing it beforehand is a bit more fraught.

Mechjeb can control a non-active craft if you're within physics distance. That's going to be nigh-on impossible during launch though. Why do you need to be able to do this? If you just want to launch three craft into the same place then stack them onto the same launcher.

Benefit of hindsight, innit.

If that was true people wouldn't spend so much money and endure so much pain for cosmetic dental work.

One of the biggest strategic lessons of WW2 was that the dominant weapon at sea is the aircraft. That's why the Germans considered air superiority over Britain a precondition of risking a cross-channel amphibious operation. If they ruled the skies the Royal Navy would have been restricted to operating in bad weather only. I think it's a bit unlikely to consider a WW2 where Germany didn't attack Russia; pushing east was Hitler's main objective for the war. Attacks on the Low countries, Scandinavia, France and Britain were just intended to secure Germany's rear in preparation for the main fight. The Germans probably would have been ok with a peace treaty with Britain. They even tried to make offers (Hess famously parachuting into Britain to try and open talks). If we're imagining a world where Hitler's government survives the war then you're implicitly talking about one where they won on the Eastern front. That's a big enough fight that you can certainly see plenty of demand for wunderwaffen. I think Von Braun still would have found himself in the rocket business, there would have been demand for weapons that could hit deep into the Russians' Siberian industrial base.

Sexual selection doesn't necessarily have anything to do with effectiveness or efficiency. At the extreme end (giraffe necks, peacock tails, etc) they can actually make survival harder.

There's a fair amount of atmospheric gas at lower orbital altitudes anyway. The upper levels of the atmosphere do cause drag on spacecraft in orbit, and will eventually deorbit them if not corrected for. Any tiny amount of gas released by engines would have a negligible effect compared to something the size of Earth's atmosphere.

Sexual selection is all about who gets to mate and how often. Mutations can confer resistance to disease, or just about any positive change you can think of. I disagree, we've changed the environment so that it suits us better, so our fitness has increased substantially (though not due to evolution). Besides, there are new selective pressures in the modern environment, the main one leaping to mind is car accidents. It's certainly conceivable that we'll pick up adaptations that make us less likely to be killed behind the wheel. I'd also be surprised if our brains didn't change to adapt to the high levels of information we're required to process in modern life.

Actually that's not true. There's still a lot of evolutionary pressure. Natural selection might be of reduced (but definitely non-zero) impact now that we have medicine, but sexual selection is still very much alive and kicking (perhaps moreso as we have less children and are more picky). There's also other mechanisms at work in evolution such as mutation, genetic drift, and horizontal gene transfer. It's a common misconception that we've stopped evolving. You can't really stop it.

There's a whole heap of parts that don't function that well in our current bodies (wisdom teeth, apendices, etc). Heck, we're not even finished adapting to standing upright yet, which is why just about everybody gets sore knees and backs. Your body is a work in progress. Mother nature hasn't finished yet, and never will.

If I notice any, I'll let you know. KSP seems to be pushing updates out at a good pace considering where it is in the development cycle.