ARS

LMAO

If you're a mad supervillain with a goal to destroy the world, what's the cheapest way to do it using existing technology? (doesn't have to blow up the whole planet, just rendering it uninhabitable is enough)

So I recently saw a review on Youtube about a movie "The Wandering Earth". In case you don't know, it's a science fiction movie with 'science' part being so bad, it makes "The Core" science looks like "The Expanse". Let's get with the premise in a nutshell: The sun is expanding, we need to save humanity, we built thousands of city- sized rocket engines on Earth's surface and fly the damn planet like a spaceship straight to Proxima Centauri by using Jupiter to do gravity assist, which then goes haywire when one of the engine shuts down, leaving the planet with insufficient thrust and now it's being pulled into Jupiter, and the only way to save the humanity is by igniting Jupiter's atmosphere so the shockwave would throw the Earth out of Jupiter's gravity well But that's not what I'm gonna ask here. Understandably, the movie is being mocked to death, mainly from being ignorant with so many laws of basic physics, astronomy and orbital mechanics. Most of the critics tend to point out about how insane the idea of putting rocket engines on Earth's surface is (and how it would mess up with Earth's geology and atmosphere), but one comment struck my interest: So it's basically using Moon's gravity interacting with Earth, pulling at each other, and use that as a means of manipulating Earth's trajectory. Now I know the scale involved here (especially in terms of engineering) is so mind-bogglingly large, but assuming the moon's orbit could be manipulated (and you really don't care about it's effects on Earth's inhabitants), is this idea makes sense (In terms of physics)? I don't ask "is this possible", I ask "is this (in theory) possible?"

As steady stream of radiation and particles continuously emitted from Black Hole as Hawking radiation, there would be a point in time where black hole's mass loss would eventually caused it to cease to exist and die. However, as black holes also moves through universe, assuming it keeps feeding from stars and planets (devouring their mass), is it theoretically possible for black hole's lifetime being continuously extended? (at least until there's nothing left to devour)

Just wanna ask if you can detect other sub by using that method (active ping far away from the sub)

But the problem is, the defending sub already knew the location of the emitter and already expect a return when they trigger the ping. The defender knew where the location of the emitters, where to look at the moment they trigger a particular ping as well as the underwater topography of the area they defend. On the other hand, the attacking sub is clueless and has no idea about the pingers' placement or even if there's such a thing in the area in the first place and expect there's only defending sub in the area. They are not expecting an active ping, much less a return from pingers they don't even know the location about (they might even mistake a ping from a buoy as defending sub's ping)

Yes, that's what I mean: detecting a target underwater using active ping, except you're not the one doing the ping, but preplaced active pingers placed beforehand (and you already know the locations)

Question: Is it possible for a submarine to do standoff active sonar search by using separate sonar emitters outside of the ship (as in, in the form of buoys, underwater emitters, etc.). Let's say for example submarine A is defending an area, and it already pre-place these emitters around. Then, enemy submarine B is entering A's patrol area. If A knows that B is entering the area, could A detect B simply by staying on passive sonar while periodically pinging the active sonars from the buoys and listening to the echoes to locate B? (could either do sonar pings from the buoys one-by-one or several of them at once)

After long hiatus, I finally go back playing KSP again feels good to be back

How hard it is when it comes to storing rocket fuel in space compared on Earth? Is it easier or harder to store? (especially cryogenic ones such as liquid Hydrogen and Oxygen)

So technically, instead of Fuel-Air-Explosive, we got Fuel-Space-Explosive?

LMAO

If you mix oxidizer into flamethrower fuel, could you (in theory) use flametrower in space? How effective it's gonna be? I assume the damage comes more from overheating the target due to horrible heat dissipation in space instead of burn damage

Does lower stall speed: -Affected by the size of lifting surface area (if it's indeed like that, does flying wing design inherently have much lower stall speed than conventional design by essentially having the entire underside of the craft as lifting surface?) -Beneficial for carrier landing when there's limited runway length? -Beneficial for maneuvering during active combat? -Have negative effect on aircraft?

Microwave requires water inside the food to efficiently heat it, but despite this, some things that have very little water inside do heat up in microwave. Fats for example, still heat up, albeit rather inefficiently. The classic example for this is the discovery of microwave oven itself where a chocolate bar melts due to a very badly shielded microwave emitter. Functionally, any polar molecule will work with microwave, but water absorbs microwaves better than others. If your food absolutely don't have any water inside, the result will vary - but generally, either no, or so little it’ll hardly make a difference. Microwaves bounce off metal, and vibrate polar molecules. Water is tiny, very polar, and very much present in almost all food, so it’s the most ubiquitous. While there are other polar molecules in various food items, there’s just not enough to absorb enough heat to matter