One time when Mark Watney entered the airlock      the plastic-like wall broke. It looked like air started coming in even though the pressure outside should never be higher than the one inside. At the end the whole airlock exploded.   I'm having hard time imagining why this happened. How is this explained scientifically?
114064
In The Martian, the "Hab" explodes at some point in the film, specifically the time that the airlock blows out.   Is it explained what exactly happens that causes this? I watched the film in the U.S. and English isn't my first language, so some details may have been lost for me.
69278
Suppose a sticky substance is thrown at wall. The initial momentum of the wall and substance system is only due to velocity of the substance but the final momentum is 0. Why is momentum not conserved?
30213
A  apparently had tons of stuff not shown in English ones.  One of the most intriguing pieces for me was a scene where      ... Finn ...   armed with a lightsaber fights a stormtrooper armed with some sort of weird weapon - which Blocks the lightsaber!.    What is that weapon and how does it manage to block?  UPDATE: found an animated GIF of the fight. I hope nobody gets a headache, sorry in advance:
37686
I'm a little worried. I was using some compressed air cleaner (to be specific, Office Depot® Brand Cleaning Duster) to try to blow the dust off some dusty parts of my computer. The instructions are very explicit about not tilting it at an angle because this could cause the gases to be released in liquid form, but the parts I was trying to clean were at kind of an awkward angle, there was really no good way to get the can in at an upright angle, so some of the liquid did get on the stuff I was trying to clean, unfortunately. It evaporated almost immediately, though.  So now, what should I do? I've seen conflicting information online. Wikipedia says that the liquid form of the gases will act as a solvent, causing unwanted damage to surface coatings, so this is troubling to me, but I don't necessarily trust wikipedia as an accurate source. I have seen it said elsewhere that compressed (canned) air will do absolutely zero damage to your computer, even if you get the refrigerant (the stuff that blows out the nozzle when the can is sideways or upside-down) on your CPU/GPU/RAM/Motherboard.  So, what should I do now? I want to clean the peripherals and such that I used it on off now in the best way possible, to prevent or mitigate any further damage that may or may not have been done or will be done by the liquid. What would be the best method to use now? Just, cloth dampened with water? Isopropyl alcohol? Something else?
57871
A fundamental law of physics is, in short, that two things cannot exist in the same space at the same time.  This is easily demonstrated by dropping a relatively large mass, such as pasta noodles, into a container of water, such as a pot.  The water level will rise as it "makes room" for the pasta, and will overflow if you've put in too much of either.  Conversely, if you were to scoop all of the noodles out (presuming you had a way to scoop just the noodles, without taking along any water at all) you would see the water sink down to its original level (or lower, if it had overflown earlier).  Taking this into consideration, I see a problem with transporter technology which I'm not sure I've ever seen addressed:  What happens to the air surrounding a transport subject's origin point, or occupying the destination?  The transporter must have some means of compensating for the displacement, otherwise each transport should in theory be accompanied by a loud pop at each end - at the origin when the air collapses to fill a vacuum left behind, and at the destination when a relatively large volume of air is forced away to make room for the subject.  This effect should be even more pronounced, and perhaps even hazardous, in closed environments such as spacecraft where the air has really no place to go.  One option would be to have the transporter exchange the air (or other matter, such as dust or raindrops) at the destination for the matter of the subject, as it is being transported.  However, this is not seen as we would often notice small portions of dust storms or downpours getting dropped onto the transporter pad when people are transported into adverse weather conditions.  Imagine having that cleanup as part of the Transporter Chief's job duties.  Another option would be to process the matter from the destination through the replicator, so that it is congruous with the same volume of air at the origin.  This would be a fairly complex operation though, and could result in a lag too long to be acceptable by the laws of physics.  Come to think of it, this same (or a similar) issue should affect replicator and holodeck technology as well.  Has any of this ever been addressed canonically, either in a Star Trek episode or in technical manuals?
28738
I was just wondering... I believe that if a car travelling 50 miles per hour crashes into a wall, the result should be the same as crashing to another car also travelling 50 miles per hour (but in the other direction of course)  Is this true? Why is that?
31671
I cant understand that. If there isn't a material that makes it hard to pass, why there is a  in vacuum?
81965
In the first half of Tenet, there is a scene where The Protagonist and Neil break into Freeport and find a glass wall with bullet holes (could only find a good photo with Christopher Nolan in it):  In the next scene, we find out that these bullet holes were caused by an inverted armed man entering the room (exiting the room from their perspective) and reverse-shooting the glass, which removes the bullet holes from the future-facing perspective. This all makes sense, but raises a question: how long were the bullet holes there in the first place? Were they in place as soon as the glass was installed, possibly years ago? Or even back when the glass was manufactured?
94427
It was very cold outside, this morning, when I took the car that slept in the snow, with a simple cloth on the windshield. I entered the vehicle, drove a kilometer or so. The air inside was so cold I could see my breath (or maybe I forgot to brush my teeth). Warm air was blowing on the windshield from the inside and suddenly…  The glass in front of my became opaque, starting from the bottom (the place where the hot air was blowing) and freezing up, up, up until the whole screen was filled in about 5 seconds. It reminded my a little bit of how some baterias spread.  When I tried to remove the mist, I realised it was ice in the car. My windshield instant froze.  I know the theory behind supercooling: a very cold and still liquid can freeze when moved. I'm not sure what happened here, but there were some pretty big turns in the road before it froze. It really looked like the hot air froze the place and not the movement.  Any idea about what happened ?
22195
I think we all heard general statements like "once big enough star burns out there is nothing to prevent the gravitational collapse ending in a black hole". But I can't remember even seeing the process described precisely.  Here's the deal: at first there is a nice object, a star. Stars can be nicely modeled by general relativity, nuclear physics and statistical physics combined and very much is known about these models and it can be observed whether they agree with things like light and neutrino fluxes, surface temperature and probably also lot of other stuff I know nothing about.  After the collapse we are left with another nice object, a black hole. We know that .  The question is: what happens in-between? More precisely, between the time when all of the nuclear material has been burned out (and if possible ignore effects like reheating of the star after big enough compression) and the time where there is nothing more than just a black hole.        Give a description of what happens during the collapse?   How does the star "lose its hair"?   Can the actual collapse be solved analytically?   At what point is singularity created?      Update: I don't want to know what an outside observer will see. Instead, I'd like to find out what an individual part of the dead star will "feel" when a black hole is about to form near it. In other words, I want a complete solution (ideally analytical, but numerical would be also completely fine)  Feel free to assume anything that makes your life easier. Spherical symmetry is definitely fine. Also, if for any reason the questions don't make sense (like Cauchy problem is ill-defined in the presence of the singularity) feel free to interpret them in a way that make them sensible (e.g. assume that black hole is built from D-branes).    Also, I have a feeling that what I intended as a simple question at first ended up being pretty complex. If you think it should be split into smaller (and therefore more manageable and answerable) parts, let me know.
107261
(careful, disturbing!)  I was experimenting with some stray cockroaches that ended up falling in my bath tub overnight (there is currently an infestation undergoing in my apartment building) and I found out that they are very easily killed by simply soaking them in soapy water.  I read that soap blocks some pores in insects' bodies which leads to suffocation, which appears to be the cause of death for my test cockroaches. But what I don't get is why about a half of them died with their innards bursting from their tail end. The water wasn't too hot to make them boil. Is it that they suffocate so hard that attempting to breathe they blow out their insides? Or is it the soap's reaction with the cockroach's bodily materials? Or is something else causing this?  I remember watching a documentary on injecting various insects with hydrogen peroxide which caused much more dramatic explosions, but it's not like I was injecting cockroaches, I just sprinkled them with soap water.
106393
In  by Vernor Vinge:      She slipped Quiller's in place and turned on the oxygen feed. She recognized the smell that still hung in her helmet: The tracer stench that tagged their landing fuel.   That smell from the tracer was inside the helmet? Why he says “the smell that still hung on her helmet”? The smell was there since when?  The smell got to the helmet after she turned on the oxygen feed?
91342
In the end Mark Watney played by Matt Damon escapes in a space shuttle (don't know what it is called). I have watched the movie only didn't read the book, I have some doubts   From where did the space shuttle appear? Why it has only small energy so that he can't reach the crew?   Any help on these will be appreciated.
12897
My setup:   plastic box (~1l) with the cover painted black mat the bottom of the box covered with sponges saturated with ethyl alcohol (90%) to the limit (all over sponge capacity poured back to bottle) turned upside down and placed on ~0.5kg of dry ice.   I can see a 'rain' of particles of alcohol, but no traces.  I disassembled smoke detector and attached the sample of americium to the box. No effect.  Here is the 'rain':   Here are some pictures of the setup:          Any help appreciated.
9192
In Ant-Man, it's (briefly) explained that the Pym particle reduces the distance between molecules, allowing a person to shrink while retaining his mass and strength.  Much of the movie is consistent with this explanation. For example:   While ant-sized, Ant-Man falls from the edge of bathtub onto a tile floor, cracking the tile as though with the weight of a full sized human. He falls from a rooftop onto a car, denting the roof. He punches full sized humans, and they respond as though hit by a real punch. Another character, while tiny, is hit by a speeding toy train. The train is knocked aside as though it hit a full sized human.   But then there are things that appear totally inconsistent with "mass stays the same":   Ant-Man is constantly running and climbing around on surfaces (air vents, ant tunnels, etc.) that couldn't possibly support the weight of a 200 lb man on a footprint the size of an ant. The toy train, when expanded to the size of a real train, is heavy enough to rip through a wall and crush a police car.     Hank Pym carries a shrunken tank in his pocket on a keychain. It obviously doesn't weigh as much as a tank, but it does when expanded to full size.  Another character, while tiny, gets swatted with a (normal sized) table tennis paddle, and goes flying like an insect.   Obviously the out-of-universe explanation is that mass behaves in whatever way is most convenient at the moment because it's just for fun.  But I'm curious: is there any in-universe explanation, either hinted at in the film itself or in the comic books, as to why mass is conserved sometimes but not always?
109766
do a good job explaining why the Imperial forces didn't have fighter protection for their ground force on Hoth.  But nothing there explains why the Rebels didn't use X-Wings to easily dispatch the AT-ATs and buy more time. They obviously had them available because they were sending them off with transports and some of these were obviously not sent until after "defending" the base (since a few of the pilots of the X-Wings were the Rogue Squadron pilots fighting in the Battle of Hoth).  This happens in the EU in the book  (in fact, the cover picture shows this scene) with great success and Wedge actually comments, on page 120:     Back then we were in airspeeders - undergunned and overmatched... Not the case this time [referring to being in X-Wings against AT-ATs instead of speeders on Hoth]   This indicates X-Wings can perform in cold conditions - there was snow in this environment as described by Corran Horn after he is shot down. The temperature difference between day-time on Hoth and here is unknown however.  Additionally, the X-Wings were able to destroy the AT-ATs with their laser cannons only - no grappling was required.  I suspect the answer is basically "because that would have been boring to watch on-screen" but it seems there may have been an actual in-universe reason outside of this.
113300
When the slab is pulled out of the freezing chamber, it already has a series of diagnostic panels along its edge.  One of the panels (the one nearest to Han's head) has the ability to report Han's vitals.    Considering that the carbonite freezing process at Cloud City was purely an industrial process with no medical purpose, it is somewhat strange for the final product to have such a panel.  It seems that the panel for the vitals was sourced from Cloud City itself, as it is Lando &mdash; not one of Vader's entourage &mdash; who reads it and reports that Han has survived.    My questions:   If the freezing chamber was not specifically altered for the occasion, why would it have such a diagnostic panel? If it was altered for the occasion, how far in advance was the chamber altered, and was it done by Lando's staff or Vader's people? How is the panel even powered?  Does the freezing process install a battery, too?