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Mohamed A

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  1. Tank You
    Mohamed A got a reaction from Lord_James in LIQUID WATER ON MARS YES SIR   
    Wouldn't it be very salty due to the condition on Mars? And empty from nutrients. 
     
    Also
     

  2. Tank You
    Mohamed A got a reaction from Sgt.Squarehead in The Toyota Hilux Appreciation Thread   
    Well, that's easy. Saudi Arabia.
  3. Tank You
    Mohamed A got a reaction from Jeeps_Guns_Tanks in Aerospace Documents Collection Point   
    And the list goes on, US:
     
    Aparent AN/APG–68(V5) Operations Guide, Used on F-16C Aircraft   NAVEDTRA 14014A Ch. 9 Aircraft Ordnance   Weapons File 2003-2004   AIM-4F Falcon Characteristics Summary September 1963   AIM-4D Falcon Standard Missile Characteristics September 1963   APPROVED NAVY TRAINING SYSTEM PLAN FOR THE AIM-7M/P SPARROW MISSILE SYSTEM N88-NTSP-A-50-8008C/A   NAVY TRAINING SYSTEM PLAN FOR THE AIM-9M SIDEWINDER MISSILE SYSTEM(FOR MODELS THROUGH AIM-9M-10) N78-NTSP-A-50-8105C/A   NAVY TRAINING SYSTEM PLAN FOR THE AIM-9X SIDEWINDER MISSILE SYSTEM N88-NTSP-A-50-9601A/A   APPROVED NAVY TRAINING PLAN FOR THE AIM-9M SIDEWINDER MISSILE SYSTEM (FOR MODELS THROUGH AIM-9M-8) A-50-8105B/A   DRAFT NAVY TRAINING SYSTEM PLAN FOR THE AIM-54 PHOENIX MISSILE N88-NTSP-A-50-8007C/D   APPROVED NAVY TRAINING SYSTEM PLAN FOR THE AIM-120 ADVANCED MEDIUM RANGE AIR-TO-AIR MISSILE N88-NTSP-A-50-8111C/A   A-10/GAU-8 Low Angle Test Firings Versus Simulated Soviet Tank Company NPS-50-80-008   A4D-2 Standard Aircraft Characteristics   Naval Air Training And Operating Procedures Standardization Manual A-4A/B/C   F-16A-B MLU Pilot Guide Part 1   F-16A-B MLU Pilot Guide Part 2   Pilot Operational Procedures of F-16   USAF Test Pilot School F-4 Phantom II Guide   USAF T. O. 1F-4C-1-2 Flight Operating Difference Supplemental Data USAF Series F-4E Aircraft Thunderbird Configuration   NATOPS Flight Manual Navy Model RF-4B Aircraft NAVWEPS 01-235FDC-1   NATOPS Flight Manual Navy Model F-4J Aircraft NAVAIR 01-245FDD-1   NAVAIR 01-F14AAP-1B NATOPS POCKET CHECKLIST F-14B AIRCRAFT   NATOPS FLIGHT MANUAL NAVY MODEL F−14D AIRCRAFT   XB-35 Pilots Handbook   YB-49 Pilots Handbook   YRB-49A Pilots Handbook   YF-12 Utility Flight Manual   747-400 Flight Crew Operations Manual   Boeing 747-400 Operations Manual   Saab SK35C Draken Flight Manual SFI FPL SK35C 29 October 1994   YF-23A DECLASSIFIED UTILITY MANUAL   NATOPS FLIGHT MANUAL NAVY MODEL AV-8B/TAV-8B 161573 AND UP AIRCRAFT   Now, an important note: My interest in Aviation is not as high as my interest for Ground/Mechanized forces. Most of these manuals, books, etc were collected by my friend.            
  4. Tank You
    Mohamed A reacted to AutumnStorm in Fucking NERA everywhere   
    Long time lurker, just wanted to thank you guys for this thread. Working on a self-designed MBT, and this was probably the easiest-to-find source for 'composite' armor construction. I honestly thought for a time that these tanks were just covered in these thick sandwiches of ceramics and metal. >_>
     
    Thanks a ton for the reference material.
  5. Tank You
    Mohamed A reacted to Collimatrix in ATGMs and RPGs for infantry - a thread for rebels around the world to choose their ATGM supplier.   
    The soldier on the right of the picture is hand-feeding this poor orphan baby rocket launcher so it can grow up to be a big, strong RPG-29.
  6. Tank You
    Mohamed A reacted to Collimatrix in An Analysis of the GSh-18 Pistol   
    56K unfriendliness follows:


     
    Artistic 3D cutaway of the GSh-18 from Abiator
     
    In the early 1990s, the Russian military began looking for a replacement for the long-serving Makarov PM pistol.  The Makarov, while a sound and simple design, was an old-fashioned design that could not take advantage of the latest advances in polymer and ammunition technology.  A certain Austrian businessman had shown that it was quite possible to make pistol frames out of injection-molded plastic instead of laboriously milling them out of steel or aluminum, and the world had well and truly taken note.  In addition, powerful new armor-piercing ammunition had been developed in Russia that was too much for the simple action of the Makarov pistol to handle.
     

    The 7N31 9x19mm round.  The bullet consists of a steel penetrator wrapped in a lightweight jacket.  The propellant burns at extremely high pressure for a 9x19 round and will wreck Glocks. 
     
    The two leading contenders were the GSh-18 and the PYA.  Both designs used locked breech operation with very beefy locking geometry in both designs to handle the large bolt thrust of the new armor-piercing ammo.  Additionally, both designs featured two-column magazines to give them much greater capacity than old PM (17 rounds for the PYA and 18 for the GSh-18).  However, while the PYA used a hammer and a traditional metal frame, the GSh-18 was quite in line with the latest thinking in small arms design and used striker firing and a polymer frame.
     

    The PYA pistol
     
    In any event, the economic and political chaos of the 1990s permitted only limited replacement of the Makarov within the Russian military.  The 1950's vintage PM is still a common sight with Russian soldiers.
     

    A Russian soldier with a slung AK-74M reloads his Makarov pistol
     

     
    The GSh-18, from Forgotten Weapons
     
    The GSh-18's unusual aesthetics and excellent lineage earned it plenty of attention from weapons nerds in the West.  Anyone familiar with Soviet aircraft armament knows the names Grayazev-Shipunov.  Could this pistol be a diamond in the rough?  A future champion, waiting to explode onto the world market?  A Russian Glock?
     
    Well, thanks to a set of pictures that LoooSeR posted from photographer and MVD operator KARDEN, we now know that the answer is NO.
     

     
    The quality of construction of these pistols... leaves something to be desired.  In fairness, some of the roughness is because this particular specimen has been hit with a file to de-fang it; apparently slide bite is a problem with this design.  Still; the huge gaps between parts, the very rust-colored finish... it's something that a tribesman with a hammer in the Khyber pass might take pride in, but it's damn rough for a mass-produced product.  Karden has commented on several other eyebrow-raising flaws of the design.  An unacknowledged champion it is not.
     
    But the GSh-18 does have some novel features that are worthy of note and investigation.  Take note, aspiring pistol designers who want to design a Glock-killer (I'm pretty sure S&W execs sit in front of a giant poster of Gaston Glock, chanting "To the last, I grapple with thee; From Hell's heart, I stab at thee; For hate's sake, I spit my last breath at thee." over and over again).  This design has some spiffy features that deserve copying.
     
    How spiffy?  Let's start with the fact that the slide isn't a single machined piece.  It's two stamping and a machined lockup insert permanently attached to each other with a removable breech block:
     

     
    Again, try to ignore the rough quality of the actual construction, and look at the contours of the parts.  The radial ring of locking splines inside the slide is separated from the rest of the slide by a slight step.  Furthermore, going from the rear portion of the slide to inside the locking ring this inside diameter gets larger, while going from the muzzle end back this diameter gets smaller.  Looking inside the return spring tunnel, we see an acute inside angle between the locking ring and the return spring tunnel.  All of these features show that the forward part of the slide is comprised of three parts that are permanently attached together.  The locking ring is one piece that is most likely broached before being attached to the main portion of the slide and then to the return spring tunnel front piece.
     

     
    This picture shows that the breech face of the slide is a separate part that comes off for disassembly.  There are several small advantages of this arrangement.  Instead of laboriously machining the slide from a single piece of bar stock, the breech face can be made separately and inserted into a comparatively simple slide that is "U" shaped in cross section.
     

    Laboriously making the slide from a single piece of bar stock, from Brian Nelson's tour of the STI factory
     
    In fact, the KBP Instrument Design Bureau has gone one better on simplifying the construction of the slide.  Look at it carefully:


     
    The sides and top of the slide are of a consistent thickness everywhere.  That's right; the GSh-18 has a stamped slide!  Albeit, it's one of the thickest stampings I've ever seen in a personal firearm.  This is rather similar to early SIG P220 series handguns:
     

    A comparison of an early, stamped SIG P226 above and a later milled model, from TTAG
     
    Considering that the stamped SIG P226 was changed to a milled slide to prevent the slide and breech block from separating when firing very hot ammo, it is impressive that the GSh-18 uses this sort of construction given that it is designed for a steady diet of the extremely energetic 7N31.
     
    For high-volume this sort of slide construction would be much cheaper and faster than the all-milled construction seen in the widely-copied Austrian pistol (The Glock With a Thousand Young).  The difference might not be large, but as I've said before, anything in a pistol design that's even slightly cleverer than a Glock deserves attention.  Additionally, the two-piece construction of the slide would make caliber conversions easier.  A caliber conversion kit would only need to consist of a new barrel, breech block and magazines for the new caliber.
     
    The GSh-18 is a rotating barrel pistol design.  This itself is nothing new; the patent on that system of operation dates to 1897, but the implementation is unusual.  In a typical rotating barrel pistol, the locking occurs at the rear of the barrel, near or in the ejection port and is effected by a few large lugs.  The Beretta PX4 is typical:
     

    Beretta PX4 from the Genitron review
     
    In the GSh-18, however, the locking occurs near the front of the barrel, on the rearward of the two sets of radial barrel projections.
     

     
    The forward projections are not locking lugs; they are beveled on the front and lack witness marks from locking.  Furthermore, the locking ring has only one set of splines.  The purpose of the forward pseudo-lugs is not clear to me, but they are probably for some prosaic purpose like keeping shit from getting in from the front of the gun.
     
    There are a few advantages to this arrangement versus the traditional rear location for locking lugs in a rotating barrel pistol.  In a typical rotating barrel pistol with the locking lugs near the firing chamber, there must be a large amount of dead space inside the slide to accommodate the locking lugs when the slide recoil to extract and eject.  This gives most rotating barrel pistols fairly chunky slides:
     

    CZ 07 with tilting barrel on the left, Grand Power P1 mk 7 with a rotating barrel on the right.  From the Walther forums.
     
    The GSh-18's locking lug arrangement neatly sidesteps this problem, although the designers ignored this fact.  GSh-18 has a very wide slide with a lot of free space inside:
     

    GSh-18 and PYA compared
     
    So the designers of GSh-18 discovered a solution to one of the drawbacks of rotating barrel locking, even though they did not take advantage of it!
     
    Because the slide is stamped, and stampings (especially of that thickness) are somewhat limited in how many fine details and contours they can have, the interaction between the slide and the frame works differently in the GSh-18.
     
    Like other short-recoil automatic pistols, the barrel and slide of the GSh-18 are locked together at the moment of firing.  Recoil flings the barrel and slide rearward, which causes the lug on the bottom of the barrel to ride over a helical cam cut into a machined piece of steel located in the frame (this piece also acts as a locator for the return spring, and a mount for a spring-loaded claw whose purpose will be discussed shortly):
     

     
    The barrel then stops against this piece while the slide continues recoiling.  This causes the slide to extract the spent case and eject it.  The slide runs out of velocity as it compresses the recoil spring.  Once it has completely compressed the spring, the slide begins moving forward, which causes it to pick up a new round from the magazine.  Up to this point, the operation of the GSh-18 is like any other recoil-operated pistol.
     
    The difference is with the feeding of the new round into the firing chamber of the barrel.  In most other designs there is some interference geometry between the slide and barrel that prevents the barrel from creeping forward from the force of the round being fed into it.  If the barrel were allowed to creep forward, it would slide back over the helical cam cut and move into the locked position.  This would cause the locking ring splines to bounce off of the locking lugs when the slide came forward, and the gun would not go into battery.  But the GSh-18 cannot be made with this sort of detailed interference geometry because the slide is stamped, and making this approach impractical.
     
    Instead, there is a large, claw-like lever on the right side of the frame.  When the barrel and slide initially retreat during recoil, this claw snaps over a rim on the right side of the barrel.  This claw forcibly holds the barrel to the rear until the slide levers it open at the right moment for locking to begin.
     
    This locking claw allows the use of a simple stamped slide, but it has some advantages beside that.  In a normal pistol, the interference geometry between the slide and barrel causes some amount of friction.  This means that the area where the slide rubs against the barrel is a critical lubrication point:
     

    Lubrication points for a Glock pistol, from the USA Carry lubrication gude
     
    So the GSh-18's slide loses a little less energy from this rubbing, and is also made a little less sensitive to the condition of the lubrication around the barrel.
     
    This is probably as good a place as any to mention that certain features of the GSh-18 bear more than a passing resemblance to the ill-starred Colt All-American 2000:
     

     
    The multiple, radially symmetrical locking lugs of the barrel (relocated on the GSh-18 to the front, of course), the two-piece construction of the slide and broad similarities make me wonder if the All-American 2000 was a starting point for the design of the GSh-18.  If so, it would make the GSh-18 the second time that this design family with visionary qualities was let down by sub-standard manufacturing.
     
    Perhaps the third time is a charm.
  7. Tank You
    Mohamed A reacted to LoooSeR in Ukrainian armor - Oplot-M, T-64M Bulat and other.   
    They don't want to start full-scale production of those. A lot of their projects don't involve changes in engines, autoloaders, gun mounts, or any other work that demands a lot of expansive R&D.
  8. Tank You
    Mohamed A reacted to LoooSeR in Syrian conflict.   
    Release the Captain Obvious! 
  9. Tank You
    Mohamed A reacted to Khand-e in Syrian conflict.   
    Considering it's you, I thought your suggesting would be closer to "Splitting multiple atoms over the Syrian state."
  10. Tank You
    Mohamed A reacted to Collimatrix in The Small Arms Thread, Part 8: 2018; ICSR to be replaced by US Army with interim 15mm Revolver Cannon.   
    Let's all take a trip back to the late 1970s and early 1980s.  This was the time of punk.  This was the time of despair.
     
    Punk was all about minimalism; strip everything down to a few chords, wear clothes you fished out of a garbage can or made yourself and infect yourself with parasitic worms so that when you vomited on some other asshole in a fight, they got parasitic worms too.  It wasn't pretty, but it was cheap and it worked.
     
    Punk was about to hit pistol design in a big way.  The aglockalypse was just around the corner.  The glock is the practical application of punk to the art of small arms design.  It's reminiscent of John Browning's early striker-fired design prototypes for the hi-power, only made out of plastic and missing half the parts.  Not pretty, but cheap and it sure does work.
     
    The world was very different in the punk era.  Remember that in the United States, violent crime increased dramatically in the late 1960s.  In the 1970s they were still figuring out what to do about that.  They hadn't had a few decades for the idea that gunfights were just something that might happen day to day to sink in, so the art of practical handgun usage was in a pretty sorry state.
     
    Or rather, practical handgun knowledge was in a hilariously bad state at the time.  I read through a police marksmanship manual from the late 1960s or early 1970s; it's like an infantry tactics manual written pre-WWI.  It's heartbreakingly naive because they hadn't seriously had to seriously think about the problem before then.  They had come from a more peaceful world, and were still getting their bearings in the grimdark of the 20th century.
     
    This police marksmanship manual still taught the FBI crouch.  The FBI crouch is a sort of distillation of the WWII-vintage Fairbairn-Sykes theory of gunfighting, which emphasized speed over accuracy.  The idea behind the FBI crouch is that you crouch down so that you're harder to hit, and you sort of get your dominant arm that's holding the weapon into a repeatable, ergonomically neutral alignment with the rest of your body so that you can aim with your entire body.  As you can see, this isn't a shooting stance that allows you to use the pistol's sights.  In some variants of the stance, you cross your left forearm over your torso so that incoming bullets have that much more flesh to go through before they start hitting your vital organs.
     
    Basically, it's the sort of theory of how to gunfighting that you might come up with in a society that, until recently, hasn't been doing a whole lot of gunfighting.
     
    Everything was in a more primitive state than it is now.  Nowadays you can go into a gunstore and have dozens of brands and styles of pistol ammunition to chose from; hollowpoints of all descriptions line the shelves, each promising to kill people more dead than the next one.  Oh, and you can buy full metal jacket if you need something cheap for practice.  Back then, full metal jacket was the fancy stuff; the most common ammo was cast lead.  Also, cops weren't totally sold on automatic pistols until about halfway through the '70s, they still mostly used revolvers.  Also, almost nobody owned a handgun.  It was considered weird.  Owning a rifle or a shotgun was perfectly normal; what else are you going to go hunting with?  Owning a handgun was weird because handguns are for shooting people, and why are you even thinking about shooting at people you weirdo?  The laws and court precedent for self-defense cases were a lot different then too.  Formerly peaceful society, still coming to grips with the grimdark.
     
    So, secret about Beretta; they basically want to make hunting shotguns and make up-scale hunting apparel.  They can't design automatic firearms actions to save their lives.  Whenever they have to make something automatic they rely on Germans to design the things for them.  The AR-70, for instance, was originally a joint design effort with SIG (SIG's evolved into the SIG-540/550 series).  The ARX-160 was designed by Ulrich Zedrosser, who, as you might surmise from his name is not Italian.  The Beretta 92 is the last in a line of Beretta pistols that started off basically as clones of the Walther P-38.
     
    You can imagine it; Beretta in the 1970s doesn't really know what makes an automatic pistol a superior combat piece, although they've been making clones of the Walther action long enough that they can make them work very well.  Cops don't know how to gunfight either; all they know is that these automatics seems a whole lot easier to shoot yourself with than revolvers, so they're going to need some sort of super-duper double safety device.  Some want double action with a decocker, some want a safety as well, someone want a combined safety decocker...
     
    So Beretta shrugs their shoulders and tries to please all these cop agencies.  Obviously, they're mainly going to be selling these things to cops and military and a very small number of weirdos.
     
    Meanwhile, Jeff Cooper, Jack Weaver and a small but growing number of practical pistol competition shooters are figuring out how to actually fight with a handgun.  Meanwhile, in Austria, long-standing armament maker Steyr is about to get a nasty surprise when the Austrian Army holds a competition for their next pistol.
  11. Tank You
    Mohamed A reacted to Collimatrix in Current Reads Thread   
    Yep.  I have yet to read any novels by SM Stirling that don't contain generous helpings of his weird sexual fetishes.  Even some of his short stories do.  Apparently one of the most common menaces of the multiverse is the transdimensional lesbian space nazi.  The goddamn things are everywhere, just waiting to jump out of the nearest interplanar portal, flex their muscles and start burning your cities and raping all your nubile women.
  12. Tank You
    Mohamed A reacted to Walter_Sobchak in 2016 Presidential Election Thread Archive   
    If there had been more civilian casualties we would have  to rename it the Uncivil War.  
  13. Tank You
    Mohamed A reacted to LoooSeR in Syrian conflict.   
    Head of Human rights watch. 
  14. Tank You
    Mohamed A reacted to Belesarius in Current Reads Thread   
    Several... not just one of his stories, but several of them, notably the Draka Series have transdimensional lesbian space Nazis as characters. 
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    Mohamed A reacted to Militarysta in Fucking NERA everywhere   
    Yes, I have a some "hard data" :-)
     
    Polish very very primitive NERA for BRDM-2 upgrade, it was study project:
     




     
    Offcial statment after tests:
     
     
    translate:
     
     
     
     
    And second:
    NERA layout effectivnes for diffrent energetic material in "bulging plates":
     

     

     
     
     
    if You want I can post more resercht like this above.
    More or less - typicle SINGLE NERA layer vs typical (copper cone, RDX melt) SC warhed will give circa 22% penetration reduction.  In case other then rubber material - wy have circa 27% reduction for rather NxRA material then pure NERA. Not very impressive?
    Vell, in modern tank we have a lot NERA layers:
     

     

     
    (my model of known M1A1HA side armour...)
  17. Tank You
    Mohamed A reacted to LoooSeR in General news thread   
  18. Tank You
    Mohamed A reacted to LoooSeR in Syrian conflict.   
  19. Tank You
    Mohamed A reacted to xthetenth in I Learned Something Today   
    Odds are that one torpedo against an Iowa would have damaged her range and speed more than her chances of staying afloat. I'm not sure how well her shafts were protected, there's always the chance of a hit like PoW took, but other than that modern battleships usually did pretty well against contemporary torpedoes. US carriers that had a TDS (Jesus fucking christ, Wasp) usually did pretty well, I bet the UK ones would have done fine, since it seems the Japanese problems were poor ventilation and avgas storage that was pretty weak against shocks, and that's particular to their ships.
     
    As an example, the North Carolina ate a torp from the spread that killed Wasp just forward of the number 1 turret. That wasn't really back far enough to catch the TDS full on, but her list was righted quickly and she was able to maintain formation at 26 kn. On the other hand, the Kongo ate two torps from the Sealion, flooded two of her boiler rooms, and caused progressive flooding (going fast enough to keep the sub from a follow on shot caused wave action to hammer away at her now exposed insides) that eventually caused her to list and be obviously sinking when she exploded.
  20. Tank You
    Mohamed A reacted to xthetenth in I Learned Something Today   
    I learned that I have a recurrent corneal erosion. I also learned that a go-to treatment for it is a viable way to treat my eyes not actually being very good at focusing light (PRK), so that's nice.
     
    For those who don't know what recurrent corneal erosion is, it's when the cornea and epithelium don't stick together as well as they should so when your eyes get dry in the morning the epithelium might just decide it likes the eyelid more and suddenly all the nerves at that attachment suddenly get exposed. I've got a real good idea why you get pain pills when they open the eye up there for surgery.
  21. Tank You
    Mohamed A reacted to LostCosmonaut in The Mass 5 Problem   
    In the beginning, there was a shitload of energy.
     
    Eventually (after fractions of a second), the universe cooled off enough that small subatomic particles, such as quarks, could form. Later, it cooled off enough that protons, neutrons, and electrons, the basic building blocks of atoms, could exist.
     
    These nucleons combined to make the atoms we all know and love. Hydrogen and its varieties; protium, deuterium, tritium. Helium-3 and helium-4. But at that point, everything just about stops. Why?
     
    As it turns out, there are no stable atoms with a mass of 5. Sure, you can smash together bits in a lab to get atoms with mass five. Helium-5 (2 protons, 3 neutrons) decays in 10-24 seconds, many orders of magnitude quicker than even exotic superheavy transuranic isotopes. Lithium-5 disintegrates almost as fast. (To my knowledge, beryllium-5 and boron-5 do not exist, and if they did we could assume they would likewise be unstable). The hyperphysics site has a bit about it here; http://hyperphysics.phy-astr.gsu.edu/hbase/astro/mass5w.html
     
    But why is helium-5 so unstable? Tritium has twice as many neutrons as neutrons, and while it's unstable, it still has a half life measured in years (about 12 of them). If you counted one bacterium every half life of helium-5, you could count all the bacteria on Earth a hundred times over in tritium's half life (thanks wikiped). This is despite the fact that helium-5's neutron-proton ratio is 1.5/1; there are numerous nucleons with a ratio greater than this, even notoriously stable lead-208. (Lithium-5's instability is not surprising, as a nucleon with more protons than neutrons. Although carbon-10 with the same proton-neutron ratio has a half life measurable in whole seconds.) Nuclei with even protons and odd neutrons are common, odd-odd pairings are usually more unstable (unless you're tantalum-180m). In short, (I'm sure there is a good reason, but I'm both not a trained nuclear physicist and mildly intoxicated right now.)
     
    But what does this all mean? As the early universe cooled, atoms were able to fuse together into heavier elements. But the lack of a stable mass-5 isotope stopped this. A few helium and hydrogen nuclei were able to make lithium and beryllium isotopes with mass 6 and 7, but the lack of a mass five intermediary meant that this could only happen through collisions of existing heavy atoms (rather than adding a single neutron or proton to another atom). The lack of a stable mass 8 isotope put a firm stop to the process. As a result, the vast majority of the universe end up as hydrogen and helium. As it turned out, this is the perfect fuel for stars. Red dwarfs, the most common type of start, are too small to fuse lithium, beryllium, boron, and other heavy elements. If helium-5 or lithium-5 were stable, the universe would be completely unrecognizable.
     
     
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  24. Tank You
    Mohamed A reacted to LostCosmonaut in Too Fast to Die; Tantalum-180m   
    Everybody here is probably familiar with the concept of isotopes. Different atoms of the same type might have different amounts of neutrons, giving them different properties. Two of the most well known isotopes are Uranium-238 and -235, but every element has multiple isotopes. Some of these are stable, while others decay in fractions of a second.
     
    Sometimes, when a particular isotope gets excited (energy added to the nucleus), it can enter a "metastable" state, where it holds on to the energy for a while instead of releasing it or decaying immediately. Most metastable isotopes decay back to their regular forms or into another atom fairly quickly, and are less stable than their parents. With one exception; Tantalum-180m.
     
    Tantalum-180 has a half life of about 8 hours, decaying to hafnium or tungsten. Tantalum-180m, despite containing more energy in its nucleus, does not do this. In fact, it has never been observed to decay. It is predicted that -180m should decay, either to tantalum-180, hafnium, or tungsten, but this has not yet been seen to happen. Based on present data, Tantalum-180m has a half life of at least 1015 years, far greater than the age of the universe. It is believed that Tantalum-180m is produced in supernova explosions, but the isotopes rarity and poorly understood nature means that scientists are unsure.
     
    The reason behind tantalum-180m's stability is actually the amount of energy it has. This energy is stored as angular momentum in the nucleus, and is commonly referred to as nuclear spin. Most atoms have a nuclear spin of 0 or another small value, such as 1/2 or 3/2. Tantalum-180m has 9, while Tantalum-180 has 1. This means that a very large amount of energy must be released from the -180m nuclear at once to decay (about 75 keV, corresponding to soft X-rays). Such an energy release happening all at once is extremely unlikely. As a result, Tantalum-180m is stuck in its metastable state, with too much energy to decay. It is literally too fast to die.
  25. Tank You
    Mohamed A reacted to LoooSeR in Syrian conflict.   
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