After the box radiated off it’s excess energy, from being placed there, it would eventually come to equilibrium at what is sometimes called “the temperature” of space. Actually, AIUI, this is simply a measure of the heat energy remaining from the Big Bang (or whatever the creation of the universe might have been). It’s what was measured first in the 60s using radio telescopes, and is about 2. something degrees above absolute zero. According to Wikipedia it’s called Cosmic microwave background radiation.
But that’s assuming your thermometer can read that low a temperature. Currently, AIUI, there is no single thermometer that actually is useful for reading temperatures at the human scale, say 273 K, going down that low.
Again, if anyone with better knowledge of this stuff cares to correct me, I know I’m playing fast and loose with definitions and explainations - it’s just meant to be sunday supplement level stuff.
People typically think of space as cold, but in fact space, being a vacuum, essentially has no temperature at all
but that’s neither here nor there.
‘Cold’ & ‘hot’ refers to a perceptual quality. ‘Temperature’ is a measure of energy. Unless thermoception is completely missing when in space, an exposed human will register some quale, and I’m guessing, will feel cold.
I’d wager that much of the perception of cold would be from the evaporative cooling as fluids boil off (and from) the outer tissues. Which would be an artifact, not of space’s inherent heat or cold, but rather a transient effect being felt as your body responds to the change in pressure.
In the interests of science, I’ll let you volunteer to tell us what it really feels like.
Chefguy, see if this helps: A thermometer, whether in space or on earth, only measures its own temperature. It’s just that if you stick the thermometer under your tongue, the exchange of heat between the thermometer and your body results in the thermometer being at the same temperature as your body.
Space itself doesn’t have a temperature per se, because temperature is a property of matter, of “stuff” so to speak. When people talk about the “temperature of space”, they really mean “the temperature stuff ends up at if you put it in space.” The thermometer would measure whatever temperature it ended up having based on how much sunlight it was absorbing and other factors like that.
Since I seem to have beat Chronos to reading this thread, I’ll be the standard physicist.
OtakuLoki is more or less correct, with some minor corrections. Temperature is a measure of the average kinetic energy of whatever particles you are interested in (the molecules in the atmosphere surrounding you, the molecules in your pool, etc.) Even in a solid, the atoms, or molecules, or what have you are moving. (This motion is not Brownian motion, however.)
You don’t have to worry about putting your thermometer in lead. The radiation of which OtakuLoki speaks is mostly light and infrared, etc. So, you can shield the thermometer by putting it in the shade.
Finally, you might wonder how space can have no temperature and a temperature of 3.2 Kelvin (3 degrees Centigrade above absolute zero.) Bricker simply simplified. Even in space, there are photons and neutrinos and who knows what else flitting about. The photons are at a temperature of 3.2 K. For all practical purposes, neutrinos do not interact with your thermometer, or you, so they don’t count.
Although such “pinfire” weapons and matching cartriges were were made from 1828 to the mid-1880s (more in Europe, especially France, than the US), and the mechanism is still used for watchfob novelty guns (2mm or so), the normal cartridge, since the 1850s, has been either rimfire or centerfire. In both of these designs, the firing pin is part of the hammer, or is hit by the hammer, or is sprung directly, without any hammer. In no case is it part of the cartridge.
The basic difference between rimfire and centerfire is that centerfire economizes on the primer by putting it in a cup in the center, and is therefore used in most large calibers, whereas rimfire puts it all over the back of the shell, and is used in most small calibers, where the centerfire cup would be too fiddly to manufacture. Pinfire, on the other hand, strikes a pin that sticks out at right angle from the cartridge, which avoids the problem of making part of the cartridge soft, but is itself fiddly to make, fiddly to load, and somewhat fragile. Pinfire should not be confused with the roughly contemporary needlefire, in which a long firing pin penetrates the cartridge to strike a primer sitting on the back of the bullet. This had the advantage that the mechanism provided a nice anvil to strike the primer against, but the disadvantage that the needle tended to break or go out of alignment.
If we’re talking about the exercise I think we’re talking about, you were given a list of items available to you and prioritize what to carry when your ship crashed and you had to hoof it to the base. The handguns were quite low on the list, since as you surmised, they wouldn’t have much use, but they were higher than a couple of things, like matches.
The person is going to radiate heat at a certain rate dependant on how warm they are, what colour they are, what they are wearing etc. Broadly, a body at normal temperature is not going to radiate heat very fast.
At the same time, they are going to be warmed by whatever source of radiation they are exposed to. If the Sun was shining on them they’d get somewhere between a little and a lot of heat, depending on distance, for example. If they are in shade or in deep space away from any radiation source, not so much.
The net result of input and output of radiation could be either warming or cooling.
The Apollo spacecraft continually rolled to warm the side towards the sun and cool the other and regulate temperature. It also generated heat from fuel cells.
Actually, the concept of temperature can be extended past that. The simplest generalization is to say that if two objects are in thermal equilibrium with each other, they’re the same temperature. So, for instance, if you put a thermometer next to a black hole (in an otherwise-empty universe; no microwave background radiation or the like), the thermometer will eventually reach a particular temperature (above absolute zero) and stay there. That temperature can be said to be the temperature of the black hole, despite the fact that a black hole has no component particles to vibrate.
Note also that when people refer to the 3 Kelvin background as the “temperature of space”, they mean deep space, far away from everything. Close by a star, the star’s output will far overwhelm any contribution from the background. An object in Earth orbit or the vicinity (which includes the Moon, the furthest from Earth humans have ever been) will have an equilibrium temperature in the vicinity of the temperatures you find on the Earth. This should be no great surprise, since the Earth itself is an object in space at thermal equilibrium.
Well, first of all, there are a lot of various .22 - apart from .22 LR, there is .22 short and .22 WMR and some others, less popular. There is also .17 HMR. Compared to uber-popular .22 LR all other are rare, but they do exist.
Between the thermal expansion issues and the evaporation of lubricants, could you get a full clip off with an AK47 before the thing jams, overheats or just explodes?
Well, evaporation of lubricants would be IMHO biggest concern, but it takes time. On the other hand, it’s almost unrelated to actually firing - just exposition to vacuum do. So I think that straight from airlock - shooting without problem. Already in the vacuum for days, might not be able to fire at all.
Overheating wouldn’t be issue - barrel is massive enough to soak heat from a single magazine of ammo fired. It gets hot, but not enough to cause problems. Now after half dozen of emptied magazines things gets less rosey. There would be increasing chance of jams and self-ignition, as well as lower accuracy and MUCH faster wear of barrel.
Explode? No. Probably. AK-47 is gas operated, and I’m not sure if higher difference between propellant gases in cylinder and NO atmosphere outside could cause faster wear and/or breaking of parts. Maybe. Also, faster rate of fire.
So, I think that straight out of airlock you could fire a magazine or few from your AK-47, but after that it would be in bad shape - possibly worn and damaged, and in dire need of service. Left outside of your space station, there are chances you couldn’t fire that thing at all, due to evaporation fo lubricants. And if you could, then it would probably jam before emptying single magazine. Of course all above assuming that it wasn’t in the shade and therefore didn’t froze solid or wasn’t exposed to direct sunlight and therefore propellant didn’t cooked in the bullets.
I guess you could modify an existing firearm, or design one especially, to operate well in a vacuum. If anybody would do that, it’d be the Soviets; any chance that ever happened?
I don’t think so. Actually, I just realized that there ARE weapons, that most probably would work without problems in space. Underwater weapons like German HK P-11 or Russian SPP-1 would avoid most issues described in article and this thread. Little to no moving parts. Self-contained. In case of P-11 no barrel to overheat… And as a plus, elongated arrow-shaped projectiles would be great in piercing those spacesuits
Uhhh… Wha? Being a lifelong inhabitant of Earth, specifically, its surface, I can report that it is not at thermal equilibrium with its environment. I’ve seen many examples of this state of non-equilibrium, but one particular example has to do with this rotation on an axis thing it does. At a particular point on the surface, say, where I am right now, it tends to be pretty warm at this point of rotation when the nearby star is blasting the surface with radiation. Things will continue to warm even as the angle of incidence of the radiation decreases until it starts to get pretty weak and the light gives way to the interstellar darkness. The temperature then starts to drop and pretty much continues to drop until the planet comes around so that the light starts hitting the surface again.
The temperature is pretty much changing the whole time during the diurnal cycle. That even neglects other local effects that show things are not at equilibrium like the fact an exposed object will be warmer or colder than this or that one due to differing rates of radiative heating and cooling, and neither object necessarily is the same temperature as the air, which is still different than that nearby body of water. Then we have larger scale thermal phenomena like pretty much all atmospheric meteorological phenomena, ocean currents, etc. that are driven by thermal gradients.
Oh, and then there is the facts that the Earth itself is a net thermal source due to radioactive decay beneath the surface and is still cooling from its formation.
