Q:hey joe! i have a question. what would happen if you shot a gun in space? would it be the same as using a gun on earth?
Lock and load!
First off, Vsauce and MinutePhysics have you covered on a lot of the more odd aspects of that question, watch below:
I think what you probably want to know is “If I were floating in space and fired a gun, what would happen to me?”
First off, the gun would probably function normally, assuming you could pull the trigger with your space gloves (you are wearing a spacesuit, right?) and that it isn’t too cold or too hot for the gunpowder combustion reaction to ‘splode. Bullets don’t require external oxygen to fire, because the primer (the part that the hammer/firing pin strikes in order to make the powder go boom) and the gunpowder itself both contain all the oxygen they need to burn in the form of an oxidizing agent (in the gunpowder’s case, saltpeter, or potassium nitrate).
When that explosion happens, the gas is going to build up and escape out the end of the muzzle at a very high velocity. The bullet will travel out at essentially the the same velocity, since there’s no atmosphere to resist it.
Let’s say I’m space-shooting a 9mm pistol containing 124 grain ammunition (“grain” is a measure of the mass of the projectile part of the bullet). That’s equal to about 8 grams of projectile. Let’s assume 100% of my gunpowder gets converted into gas, and all of that gas and the bullet get ejected out the barrel at a velocity of 365 m/s, a pretty reasonable muzzle velocity for a 9mm pistol. The momentum of the bang is P = mv, or 2.93 kg • m/s
The law of conservation of momentum says that the total momentum of the system must add up to zero, since we started at a state of zero momentum (you were “standing still” before the gun fired). I know the total momentum of the bullet gas from above, and I know that I’d “weigh” a total of 130 kg wearing one on NASA’s Extravehicular Mobility Units:
So, solving for my velocity, we get …
… -0.023 m/s, or 2.3 cm/s backwards … not very fast, but just fast enough to out-float that space snail who I was originally firing my gun at. You do NOT want to get close to one of those guys … vicious space killers.
EDIT: This post originally said that “grains” were a measure of the gunpowder amount, which is what I have thought my whole life, and I was wrong. A cartridge’s “grain” is the mass of the projectile!
Alice in Quantumland – an imaginative allegory of quantum physics, written and illustrated (!) by a CERN physicist, doubly brilliant for flying in the face of gender stereotypes with a female protagonist who makes sense of some of the most intense science of all time.
Sometimes I’ve believed as many as six impossible things about quantum mechanics before breakfast.
In the Wikipedia entry on Extension there is this sentence:
This can be contrasted with current conceptions in quantum physics, where the Planck length, an almost unimaginably tiny quantity, represents reaching that distance scale where, it has been theorized, all measurement seemingly breaks down to that which can be subsumed at this scale, as distance only, or extension.
Extension is basically like having a form or substance,but I am unclear–maybe given the structure of the above sentence–what is contrasted by said properties in quantum physics.
Anyone out there that can extend Mike a helping hand?
I’m not exactly from the physics side of Tumblr (although I do dabble), but the above statement seems flawed, or at least a little confused. If you’re seeking the limit of extension, the divisibility argument seems like the best way to look at it. With an infinitely small knife, how many times can we slice matter into pieces before we reach the limit of its matterpieces?
The Planck length is the theoretical lower limit for distance (10^-35 meters), but physicists haven’t proven (?) that anything exists past quarks (10^-twentysomething meters). Superstrings, black hole singularities, and “quantum foam” are candidates, but those haven’t been proven to exist or measured.
Of course, I’m also not from the philosophy side of Tumblr either, so maybe I’ll shut up and let you guys correct me/add to my answer.
It’s likely the universe extends forever in space and will go on forever in time. Our results are consistent with an infinite universe.
Here is another advanced material The Slo Mo Guys caught with their Phantom Flex camera when they were recording some of GE’s research. They got to play with magnetic liquid called ferrofluid, shown in this gif, along with the superhydrophobic coatings that completely repel water. The liquid above is made of tiny particles of magnetic materials suspended in a solution. Such fluids behave in odd and interesting ways when they are exposed to magnetic fields.
I will never not reblog ferrofuids.
Serosity: liquid magnetism comes alive in this ferrofluid video by Alistair Moncur.
"Magnetism, as you recall from physics class, is a powerful force that causes certain items to be attracted to refrigerators."
- Dave Barry
If you’re not on “full whoa” after that, then this one should do it, some gooey quantum goobers from Ludmila Kovalenko:
You’ve watched this week’s video, on “The Science of Snowflakes”, right? A lot of people have asked this question:
"Okay, so snowflakes have six sides because physics, but why are they symmetrical?!”
Here, “symmetrical” means that each of a snowflake’s six arms has a similar, often nearly identical set of fractal plates and branches. What gives? If randomness and the intermolecular physics of water molecules are the only things guiding the formation of a snowflake, how does one arm have any idea what another is doing?
In your head, you might think snowflakes all look like this:
(photo by Alexey Kljatov)
Well, as the images up top show, most snowflakes don’t look like that. Snow crystals usually aren’t completely symmetrical. Instead, they are quite irregular and lumpy, full of conglomerations and corrections. The hexagonal crystal structure holds up in all cases, but the sort of perfect fractal sculpture you’ve been led to believe defines a snowflake? It’s a half-truth, at best.
Sorry. I probably should have been more clear about that in the video!
The world’s great snowflake photographers through the years, from Wilson Bentley to Kenneth Libbrecht to Alexey Kljatov, have, for the most part, chosen to only show you the most beautiful examples of snow crystals. Sometimes they wait hours, sifting through thousands of flakes with (literally) bated breath, just to capture that one perfect frigid starburst. They aren’t trying to trick you, many artists’ eyes just prefer the symmetrical ones.
That being said, even in irregular snowflakes, when it comes to the branches, sub-branches, and sub-sub-branches, there’s still a remarkable amount of symmetry. What’s up with that? Let’s retrace the path of a snowflake and see if we can find an answer.
As a speck of dust falls through cold air of a particular humidity, it acts as a nucleus of crystallization, capturing water molecules from the air into the growing crystal. And, as we saw in the video, the precise hydrogen bond angles between water molecules give us the familiar hexagonal shape, an emergent pattern that exists from the molecular to the macro scale.
All those branches off of the hexagon, each plate, dendrite, arm, prism, or whoozywhatsit that grows from the central plate, each forms at a particular combination of temperature and humidity. Consult the following:
Very cold? We get columns. Cold and high humidity? Dendrites. Cold and medium humidity? Sectored plates. Still, none of this explains how two separate arms can form complementary patterns. I know … Get to the point, Joe.
The current thinking, and I must emphasize that this part remains somewhat of a mystery, is this: During a particular snowflake’s delicate dance down to Earth, all six branches will pass through the same tiny, specific pockets of humidity and temperature, all six branches will be subject to the same air currents, all six branches will experience a nearly identical (but not totally identical) evolution.
Imagine if we played human evolution back six times! We would get similar results, perhaps, but not identical. Snowflakes really are a hell of a metaphor, man.
And when all that doesn’t work? When the journey doesn’t result in the perfect six-sided mirror reflections that float through the snow flurries of our imaginations? Well, imperfection is a part of life, whether you’re a snowflake or a human being. In both, artists tend to show us the ideal, but we must remember that there is beauty in the flaws.
And so we return to the images above, and we appreciate them anew.
Magnetism by Ling Meng - "What I am trying to focus on recently, is combining Art and Science somehow."
Created by Ling Meng a Shanghai based artist these atmospheric photos visualise the invisible force of magnetism. What we are observing acting on these iron filings in these photos is specifically known as ferromagnetism.
The iron filings have domains scattered through them, which can be thought of as smaller magnets in themselves. When a magnetic field is applied these domains to face the same direction referred to as a dipole dipole alignment, resulting in a net magnetization. A really nice video explaining this and its function in transformers is here. There are lots more artistic ways of applying these fields have a look at this ferrofluid sculptre video for example.
Past posts on magnetic levitation.