Submerge

Submerge (pronounced suhb-murj)

(1) To put or sink below the surface of water or any other enveloping medium.

(2) To cover or overflow with water; to immerse.

(3) Figuratively, to cover over; suppress; conceal; obscure; repress.

(4) To overwhelm (with work, problems etc).

(5) To sink or plunge under water or beneath the surface of any enveloping medium.

(6) Literally & figuratively, to be covered or lost from sight.

1600–1610: From the fourteenth century submerger or the Latin submergere (to plunge under, sink, overwhelm), the construct being sub- + mergere (to dip, to immerse; to plunge), the construct in English thus sub + merge.  The sub- prefix was from the Latin sub (under), from the Proto-Italic supo (under), from the primitive Indo-European upó.  The transitive form was the original, the intransitive (sink under water, sink out of sight) dating from the 1650s and becoming common in the twentieth century because of the association with submarines.  Used by submariners and others, the derived forms (resubmerge, resubmerged, resubmerging, unsubmerging et al are coined as needed and the word submerge is a little unusual in that it can be used to describe both an object going underwater (like a submarine) and water flooding somewhere (like a valley when a dam is built).  Submerge, submerged & submerging are verbs, submerse is a verb & adjective, submersible & submergible are nouns & adjectives, submersion, submerger & submergence are nouns and submersive is an adjective; the noun plural is submersibles.

The noun submersion in the sense of “suffocation by being plunged into water” was first noted in the mid-fifteenth century and was from the Late Latin submersionem (nominative submersio) (a sinking, submerging), the noun of action from the past participle stem of submergere; the general sense emerged in the early seventeenth century.  The transitive verb submerse (to submerge, plunge) was an early fifteenth century form, from the Latin submersus, past participle of submergere and etymologists suggest the modern use (dating from the 1700s) was a back-formation from submersion. The adjective submersible was formed from submerse and was noted first in 1862, the creation necessitated by the building of one of the early “submarines” used by the Confederate forces in the US Civil War (1861-1865).  The term “submersible craft” lasted for a while in admiralty use but was in the early 1900s supplanted by submarine and the alternative adjective submergible (dating from 1820) is probably extinct although there may be the odd technical niche in which it endures.

Lindsay Lohan, partially submerged, Miami, Florida, May 2011.

Fairly obviously, the construct of submarine was sub + marine.  Marine was from the early fifteenth century Middle English marin, from the Middle French marin, from the Old French, from the Latin marinus (of the sea), from mare (sea), from the primitive Indo-European móri (body of water, lake).  It was cognate with the Old English mere (sea, lake, pool, pond), the Dutch meer and the German Meer, all from the Proto-Germanic mari.  Just as obviously then it means “underwater” and that certainly accords with the modern understanding of the concept of a submarine (which the Admiralty once called “submarine-boats” and ever since, submarines, regardless of size, “boats” they have been even though some, such as the Russian Navy’s Typhoon-class submarines with a length of about 175 meters (574 feet) and a displacement of around 48,000 tons (when submerged) are larger and heavier than many ships in the surface fleet) but for the first few decades of their existence, they were better understood as “submersible boats”.  That was because they were compelled to spend most of their time on the surface, submerging only while attacking or when there was fear of detection.  However, despite them being “boats” both the US Navy and Royal Navy continue respectively to prefix their names with USS (United States Ship) and HMS (His Majesty’s Ship), ignoring anyone who points out the inconsistency.

Confederate States of America man-powered underwater boat CSS H. L. Hunley (1863-1864).

Quite when man first pondered the possibility of an “underwater boat” isn’t known but just as flight fascinated the ancients as they gazed at birds, presumably so did the fishes intrigue.  Sketches from the medieval period which appear to be “designs” for “underwater boats” have been discovered but as far as is known, it wasn’t until the 1500s that prototypes were tested and a proof-of-concept exercises some can be considered a qualified success and there were even innovations still used today such as ballast tanks but the limitations imposed by the lack of lightweight, independent power sources meant none appear to have been thought useful, certainly not for the (predictably) military purposes for which so many were intended.  The idea didn’t die however and over the centuries many inventors were granted patents for this and that and the what all seem to have concluded was that, given the available technology, an underwater boat would have to be a short range weapon capable of limited duration while submerged and man-powered by a crew of probably no more than two.  Given that, development stagnated.

The planned German Type 50 U-boat which was never launched (1918).

However, improvements in metallurgy continued and by the mid-nineteenth century, several underwater boats had been built in Europe although the admirals remained sceptical, an attitude which by many wasn’t revised even after 1864 when the one which entered service with the Confederate Navy during the US Civil War succeeded in sinking a warship nearly 200 times her displacement of 7-off tons.  However, because the method of attack was a explosive device on a long spar (the technique to ram the charge into the ship’s hull), the explosion damaged both craft to the extent both were lost.  That seemed to confirm the admirals’ view but technology moved on and by the outbreak of the First World War (1914-1918), submarines were an integral part of many navies, their usefulness made possible by the combination of diesel-electric propulsion and the development of the torpedo which meant charges detonated at a safe distance.  However, they remained submersible boats which could operate underwater only briefly.  Despite that, they proved devastatingly effective and in 1917 the Imperial German Navy’s Unterwasserboot (underwater boat (usually clipped to U-Boat)) flotillas were a genuine threat to the UK’s ability to continue the war.

German Type XII Elektroboot (1945).

In World War II (1939-1945), the course of the war could have been very different had OKM (Oberkommando der Marine; the high command of the Kriegsmarine (the German Navy 1935-1945)) followed the advice of the commander of the submarines and made available a fleet of 300 rather than building a surface fleet which wasn’t large enough to be a strategic threat but of sufficient size to absorb resources which, if devoted to submarines, could have been militarily effective.  With a fleet of 300, it would have been possible permanently to maintain around 100 at sea but at the outbreak of hostilities, only 57 active boats were on the navy’s list, not all of which were suitable for operations on the high seas so in the early days of the conflict, it was rare for the Germans to have more than 12 committed to battle in the Atlantic.  Production never reached the levels necessary for the numbers to achieve critical mass but even so, in the first two-three years of the war the losses sustained by the British were considerable and the “U-Boat menace” was such a threat that much attention was devoted to counter-measures and by 1943 the Allies could consider the battle of the Atlantic won.  The Germans’ other mistake was not building a true submarine capable of operating underwater (and therefore undetected) for days at a time.  It was only in 1945 when the armaments staff and OKM were assessing their “revolutionary” new design that it was concluded there was no reason why such craft couldn’t have been built in the 1930s because the capacity and technology existed even then.  It was a classic case of what Donald Rumsfeld (1932–2021: US defense secretary 1975-1977 & 2001-2006) would later call an “unknown known”.  The Germans in 1939 knew how to build a modern submarine but didn’t know that they knew.  Despite the improvements however, military analysts have concluded that even if deployed in numbers, such was the strength of forces arrayed against Nazi Germany that by 1945, not even such a force could have been enough to turn the tide of war.

Royal Navy Dreadnought class SSBN (Submarine, Ballistic Missile, Nuclear-powered), due to enter service in the 2030s.The concept the Germans in 1945 demonstrated in the Type XXI Elektroboot (electric boat) provided the model for post-war submarines which, once nuclear-powered, were able to remain submerged theoretically for decades, the only limitations in functional duration being the supply of food and the psychological strain on the crew.  This ability explains why they’re used by members of the “nuclear club” such as China, France, Russia, the UK & US operate them as part of their independent deterrents, equipped with submarine-launched ballistic missiles (SLBMs), armed with nuclear warheads.  At this time, the boats are undetectable and they’re still been updated or replaced but there are suggestions advances in the capability of underwater sensors might erode or even remove this advantage which would mean the submarine would follow the big bomber, the battle ship and debatably the aircraft carrier as a once dominant weapon, the time of which has passed.  Already there are those in think tanks pondering whether the loss invulnerability of the SLMB platform would make war more or less likely.  Certainly, such a situation might change the math of the preemptive strike.

Dump

Dump (pronounced duhmp)

(1) To drop something or let fall in a mass; fling down or drop heavily or suddenly.

(2) To empty the contents of something (by tilting, overturning etc).

(3) To dismiss, fire, or release from a contract.

(4) In informal (and very common) use, to end a relationship with someone (especially a romantic partner), used mostly when the action is one-sided although there are many mutual dumpings, even if some are technically retrospective.

(5) Suddenly to transfer or rid oneself of some responsibility, task or duty.

(6) In the slang of boxing (1) to knock down an opponent & (2) intentionally to lose a match.

(7) In commerce (1) to put (goods or securities) on the market in large quantities and at a low price without regard to the effect on market conditions or (2) deliberately to offer goods in large quantities or at prices below the cost of production & distribution in an attempt to drive out competition.

(8) In international trade, to sell (goods) into foreign markets below cost in order to promote exports or damage foreign competition.

(9) In computers, (1) to print, display or record on an output medium the contents of a computer's internal storage or the contents of a file, often at the time a program fails, later to be used to debug or determine the cause or point of failure or (2) as screen dump, to print or create an image file of the screen’s display.

(10) Of precipitation (rain, hail & (especially) snow), heavy downfalls.

(11) In historic use, a small coin made by punching a hole in a larger coin (called a holey dollar and issued in both Canada and Australia).

(12) A deep hole in a river bed; a pool (a northern England regionalism).

(13) In slang, to kill; to arrange or commit murder.

(14) To fall or drop down suddenly.

(15) To throw away, discard etc something.

(16) In informal use, to complain, criticize, gossip, or tell another person one's problems (often as “to dump on”); to treat with disrespect, especially to criticize harshly or attack with verbal abuse.

(17) In vulgar slang, an evacuation of the bowels; to defecate (often as “take a dump”; men especially fond of the phrase “huge dump”).

(18) An accumulation of discarded garbage, refuse etc; a tip or landfill site, also called a dumpsite or dumping-ground.

(19) In military use, a collection of ammunition, stores, etc, deposited at some point, as near a battlefront, for distribution (ammo dump, fuel dump etc).

(20) In mining, a runway or embankment equipped with tripping devices, from which low-grade ore, rock etc., are dumped; the pile of stuff, so dumped.

(21) In informal use, a place, house or town (even a state or entire country according to some) that is dilapidated, dirty, or disreputable.

(22) In merchandising, a bin or specially made carton in which items are displayed for sale.

(23) In surfing (of a wave) to hurl a swimmer or surfer down.

(24) To compact bales of wool by hydraulic pressure (Australian and New Zealand).

(25) A mournful song; a lament; a melancholy strain or tune in music; any tune (obsolete).

(26) A sad, gloomy state of the mind; sadness; melancholy; despondency (usually in the form “down in the dumps”).

(27) Absence of mind; reverie (now rare).

(28) Heavily to knock; to stump (Scottish, obsolete).

(29) A thick, ill-shapen piece (UK, archaic).

(30) A lead counter used in the game of chuck-farthing (UK, archaic).

(31) A type of dance (obsolete).

1300–1350: From the Middle English dompen & dumpen (to fall suddenly, plunge), from the Old Norse dumpa (to thump, strike, bump).  The modern senses of the transitive verb and noun are unknown prior to the nineteenth century and may either be from another source or are an independent expressive formation.  There may have been some Scandinavian influence such as the Norwegian dumpa (suddenly to fall) which may also be linked with other Germanic forms such as the Middle Low German dumpeln (to duck) and the Danish dumpe (suddenly to fall).  The use in the sense of “hole used for the disposal of unwanted items by burying” was a development of the Scots dump (hole in the ground), the Norwegian dump (a depression or hole in the ground), the German Low German dumpen (to submerge) and the Dutch dompen (to dip, sink, submerge), something obviously not unrelated to the early fourteenth century meaning “throw down or fall with force, drop (something or someone) suddenly” which didn’t exist in Old English.  The modern use is actually most modern, the sense “unload en masse, cause to fall out by tilting up a cart etc” not recorded until it emerged in American English by 1784 while that of “discard, abandon” dates from 1919.  The use in economics to describe “export or throw on the market in large quantities at low prices” was first noted in 1868 in the context of anti-competitive practices.  A dumping ground was first documented in 1842 although the term may earlier have been in oral use.  Dump & dumping are nouns & verbs, dumped is a verb, dumper & dumpage are nouns and dumpy is an adjective; the noun plural is dumps.

By 1865, the noun dump was understood as place “where refuse is dumped, piled or heaped; a repository of refuse matter” and applied originally to extractive mining as a development of the verb, the use extending to sites for discarding domestic rubbish by 1872, the earlier “dumping-ground” common by 1857.  The meaning “any shabby or dilapidated place” dates from 1899 while the use by the military to describe places for the “collection of ammunition, equipment etc, deposited at a convenient point for later distribution” was a product of World War I (1914-1918), noted first in 1915 and possibly a development from soldiers’ slang although the later war-time slang to mean “act of defecating” appears to be of civilian origin, noted first in the US in 1942.  The dump-truck was first so described in 1930s and although truck had for decades been used to dump stuff, the name was derived from the use of hydraulic rams to enable to load more quickly to be emptied by raising the load bed or freight compartment at an acute angle.

Lindsay Lohan and her lawyer in court, Los Angeles, 2011.

The “Dempster-Dumpster trash-hauling mechanism” remains familiar as the modern “dumpster”, a large, mobile container designed to be removed by a truck and taken away so the contented could be dumped in a dump, the container quickly reused.  It was patented by the Dempster brothers of Knoxville, Tennessee who ran an operation manufacturing waste collection vehicles (which would eventually include the Dempster Dumpmaster and Dempster Dinosaur).  The Dempster-Dumpster system achieved success by creating a system of mechanically emptying standardized metal containers which had been perfected between 1935-1937.  The concept of the dumpster (a standardized design able to be stored, re-used and transported efficiently) later influenced the development of container shipping.  The name dumpster became generic and was itself linguistically productive: “dumpster diving” (1979) described the practice of scavenging from dumpsters while “dumpster fire” was a figurative reference to a situation at once calamitous, foul and either insoluble or, if fixable, not worth the effort.  In use, a “dumpster fire” is similar to a “train wreck” or “shit show” but different from a “hot mess”, hot messes worth fixing because they remain in essence, desirable.  The use of “dumpster fire” spiked in the run-up to the 2016 US presidential election, used not only by both camps but also disillusioned neutrals.

The noun landfill dates from 1916 was a euphemism for dump although unlike some of the breed, it was at least literally true.  The adjective dumpy (short and stout) was from circa 1750 and the origin is undocumented but many etymologists assume it was linked to dumpling (mass of boiled paste (also “a wrapping in which something is boiled”)) which dates from circa 1600 and was from the Norfolk dialect, again of uncertain origin but the source may be Germanic or simply from “lump” (and there are those who argue dumplings were probably originally “lumplings”).  Lump was from the Middle English lumpe, from a Germanic base akin to the Proto-Germanic limpaną (to glide, go, loosely to hang).  “Humpty Dumpty” was a French nursery rhyme hero (it seems first to have been translated into English in 1810) and in the late eighteenth century it had been used to mean “a short, clumsy person of either sex”, presumably a reduplication of Humpty (a pet form of Humphrey (which was used of mandarin Sir Humphrey Appleby in the BBC Television comedy Yes Minister) although a humpty-dumpty in the 1690s was originally was a drink, a cocktail of “ale boiled with brandy” which probably tasted better than it sounds.  The construction was based presumably on hump and dump but the basis has eluded researchers.  In the late twentieth century, “hump & dump” was repurposed to describe the practice (habit, calling, tactic, whatever) of enticing a woman in order to enjoy sex and immediately afterwards leaving, never to ring or call.  It’s subsequently be claimed by bolshie women for much the same purpose; the variations included “fuck & chuck”, “pump & dump:, “jump and dump” and “smash and dash”.

Crooked Hillary dumping on deplorables, Georgia, 2016.

Big buses have long been used by politicians for their campaign tours.  They offer lots of advantages, being offices and communications centres with at least some of their running costs offset by a reduction in staff travel expenses.  Additionally, with five large, flat surfaces, they are a rolling billboard although that can be good or bad.  In 2016, one of crooked Hillary Clinton’s campaign buses was photographed in Lawrenceville, Georgia dumping a tank full of human waste onto the street and into a storm drain.  The local news service reported that when police attended the street was “…was covered in toilet paper and the odor was noxious”.  Hazmat crews were called to clean up the scene and the matter was referred to the environmental protection division of Georgia’s Department of Natural Resources.  The Democratic National Committee (DNC) later issued an apology, claiming the incident was “an honest mistake.”  Using the word “honest” in any statement related to crooked Hillary Clinton is always a bit of a gamble and there was no word on whether the dumping of human excrement had been delayed until the bus was somewhere it was thought many deplorables may be living.  If so, that may have been another “honest mistake” because Gwinett County (in which lies Lawrenceville) voted 51.02% Clinton/Kaine & 45.14% Trump/Pence although the symbolism may not have been lost on much of the rest of Georgia; state wide the Republican ticket prevailed 50.38% to 45.29%.

Dump has been quite productive.  A “dump-pipe” is part of the exhaust system in an internal combustion engine; a “brain dump” or “info dump” is the transfer of a large quantity of information or knowledge from one person (or institution) to another, although it’s also used in the slang of those working in the theoretical realm of the digitizing of human consciousness; a block dump was an image contains the sectors read from an original floppy diskette or optical disc; “dump months” are those periods during which film distributers & television programmers scheduled content either of poor-quality or of limited appeal; a “dump job” was either (1) the act of moving a corpse or some incriminating material from the scene of the crime to some un-related place, preferably remote & deserted or (2) the abandonment of an unfinished task for which the abandoner might be expected to take responsibility, especially in a fashion that makes it likely that one or more colleagues will take on its completion; the “mag dump” was military slang for the act of firing an entire magazine-full of ammunition from a fully-automatic weapon in a single burst; “dumpsville” could be either (1) the figurative location of a person who has been dumped by a lover or (2) a description of an undesirable town or other locality; to be “down in the dumps” is to be depressed, miserable and unhappy.

An electrically controlled exhaust system "cut-out", the modern version of the old, mechanical, "by-passes".  All dump-pipes work by offering exhaust gasses a "shortcut" to the atmosphere.

In internal combustion engines (ICE), there are both down-pipes and dump-pipes.  Their functions differ and the term down-pipe is a little misleading because some down-pipes (especially on static engines) actually are installed in a sideways or upwards direction but in automotive use, most do tend downwards.  A down-pipe connects the exhaust manifold to exhaust system components beyond, leading typically to first a catalytic converter and then a muffler (silencer), most factory installations designed deliberately to be restrictive in order to comply with modern regulations limiting emissions and noise.  After-market down-pipes tend to be larger in diameter and are made with fewer bends to improve exhaust gas flow, reduce back-pressure and (hopefully) increase horsepower and torque.   Such modifications are popular but not necessarily lawful.  Technically, a dump-pipe is a subset of the down-pipes and is most associated with engines using forced aspiration (turbo- & some forms of supercharging).  With forced-induction, exhaust gases exiting the manifold spin a turbine (turbocharger) or drive a compressor (supercharger) to force more of the fuel-air mixture into the combustion chambers, thereby increasing power.  What a dump-pipe does is provide a rapid, short-path exit for exhaust gases to be expelled directly into the atmosphere before reaching a down-pipe.  That makes for more power and noise, desirable attributes for the target market.  A dump pipe is thus an exit or gate from the exhaust system which can be opened manually, electronically, or with a “blow-off” valve which opens when pressure reaches a certain level.  In the happy (though more polluted) days when regulations were few, the same thing was achieved with an exhaust “by-pass” or “cut-out” which was a mechanical gate in the down-pipe and even then such things were almost always unlawful but it was a more tolerant time.  Such devices, lawful and otherwise, are still installed.

Grab from a Microsoft Windows system dump.  Although dumps contain much, of the thousands of lines one might contain, only a small string of text in one line might be relevant and users may need some assistance to interpret the result. 

In computing, a system dump is typically a commitment to a file of what exists in memory (random access memory (RAM) or on a paged volume) and they’re created usually at points of failure, creating essentially a snapshot of what was happening either at or immediately prior to the unfortunate event.  The contents of a system dump can be used to identify errors and debug programs.  A “stand-alone dump” program (a SAD or SADMP) produces a dump occupied by either (1) a system that failed or (2) a stand-alone dump program that failed.  Either the stand-alone dump program dumped itself (a self-dump) or the operator loaded another stand-alone dump program to dump the failed stand-alone dump program.  It’s less ominous than it sounds and together, the stand-alone dump program and the stand-alone dump together form what is known as the stand-alone dump service aid.  The significance of the element “stand-alone” is that the dump is performed separately from normal system operations and does not require a system to be in a condition for normal operation.  It means that except in cases of catastrophic failure (especially if involving the total loss of mains & UPS (uninterruptable power supply) power, it should be possible always to create a high-speed, unformatted dump of central storage and parts of paged-out virtual storage on a tape device or a direct access storage device (DASD).  The stand-alone dump supplies information which can be used to determine why the system or the stand-alone dump program failed.

Implosion & Explosion

Implosion (pronoubced im-ploh-zhuhn)

(1) The act of imploding; a bursting inward (opposite of explosion).

(2) In phonetics, the occlusive phase of stop consonants; the nasal release heard in the common pronunciation of eaten, sudden, or mitten, in which the vowel of the final syllable is greatly reduced.

(3) The ingressive release of a suction stop.

(4) In clinical psychiatry, a type of behavior therapy in which the patient is repeatedly subjected to anxiety-arousing stimuli while the therapist attempts to extinguish the patient's anxiety and anxious behavior and replace them with more appropriate responses.

1829: The construct (modelled on explosion) was im- + (ex)plosion.  The im- prefix was from the Latin im-, an assimilated form of in- and used to express negation (not).  The prefix -in is quirky because it can act either to negate or intensify.  The general rule is that when pre-pended to a noun or adjective, it reinforces the quality signified and when pre-pended to an adjective, it negates the meaning, the latter mostly in words borrowed from French.  The Latin prefix in- was from the Proto-Italic en-, from the primitive Indo-European n̥- (not), the zero-grade form of the negative particle ne (not) and was akin to ne-, nē & nī.  In Modern English it is from the Middle English in-, from Old English in- (in, into), from the Proto-Germanic in, from the primitive Indo-European en.  Plosion was a word from the jargon of phonetics meaning the pronunciation of a consonant characterized by completely blocking the flow of air through the mouth and was a derivative of explosion, first coming into use in 1915–20 as a shortened form of explosion.  Implosion, coined as an opposite of explosion, was first published the Westminster Review in 1829.  There was a technical need for the word because, in popular use, many chemical reactions which resembled explosions were described thus, even though, as in the case of a mixture of hydrogen and oxygen, instead of an enlargement of bulk, a positive quantity, the result was is a negative one, tending towards a vacuum.

OceanGate’s diagram of Titan.

In response to the questions raised after it was confirmed OceanGate's Titan submersible had suffered a catastrophic implosion event, US Navy sources commented on the process:  When a submarine collapses (implodes), the hull material moves inward at a speed of around 1500 mph (2400 km/h) or 2200 feet (670 m) per second and the time required for a complete collapse is about 1 millisecond.  Typically, the human brain responds instinctively to stimulus at about 25 milliseconds and those with untypically fast reaction responses can begin to act at around 150 milliseconds.  The atmosphere inside a submarine contains a relatively high concentration of hydrocarbon vapors and this contributes to the space behaving something like the compression cycle in a very large diesel engine: The air auto-ignites and an explosion follows the initial rapid implosion.  A human in these circumstances is transformed into large blobs of fats and these the extreme temperature incinerates and turns to ash in little more than a second.  Navy sources also expressed scepticism at the desirability of constructing a hull from a mixture of materials (titanium and carbon-fibre) in vessels operating at depths where the pressure is extreme (where the wreck of the Titanic lies it’s some 400 times that which prevails at sea level).  The argument is that wherever the two materials meet is the point at which, over time, a weakness is most likely to form.  Because the Titan's tubular hull was made from carbon fibre, it's thought that rather than behaving like the metals used in submarine construction, it would to some extent fragment although the nature of the disintegration won't be known until the wreckage is examined.

Engineers however noted the consequences of the explosion (for both machine and people) could differ greatly from the historic experiences of such events at depth because they all involved vessels made from metal which tends to retain its inherent integrity, even as the structural integrity of the construction fails.  Additionally, many of the previous examples were spherical so the internal forces were equalized for the split-second during the critical event whereas Titan was tubular with what would, under the stresses imposed, become detachable titanium end-caps.  Titan's hull was built from carbon-fibre which, under the specific pressure encountered would have behaved differently from metal and may have fragmented.  The physics of all of this means the temperatures and dynamic forces experienced within Titan in that split-second may have been very different from the models generated by historic experience but until the wreckage and any human remains are examined, the details of the brief event will remain unclear.  The incident however is anyway likely to discourage the use of carbon-fibre hulls in submersibles but whether it has any implications for use in aviation will be interesting.  Building the fuselages of passenger airliners from carbon-fibre has many advantages and the stresses imposed are very different to those at depth but there is no real-world data to assess how the material will behave over the decades the airframes may operate.        

Historically, the difference between a “submersible” and a “submarine” was that a submersible was a vessel which operated usually on the surface but was able to submerge for short periods for purposes such as launching attacks on other vessels or attempting to avoid detection while a submarine was able to operate underwater for extended periods.  The definitions were (more or less) formalized after 1945 when “true” submarines were developed, rendering obsolete the traditional submersibles which gained their name as a clipping of “submersible boat”.  When nuclear propulsion was adopted, the duration of the craft was extended further, the primary limitation being the volume of food able to be stored.

The definitions have shifted somewhat although traces of the older distinctions remain.  For practical purposes, a submarine is a large, complex vessel able to undertake independent and extended underwater operations and although most associated with navies, there are many civilian operators of submarines.  In recent decades, submersibles have no longer been designed for sustained surface use (although some of the recent creations by drug smugglers appear to be exactly that) and are dedicated to and optimized for the undersea environment.  They can be just about any type of vehicle or apparatus capable of operating underwater, crewed or un-crewed and in an array of sizes and configurations for use in fields such as scientific research, exploration or underwater photography.

Implosions: Implosions do occasionally afflict storage tanks and the Mythbusters television series (past masters at explosions, on this one episode they forsook blowing stuff up and imploded something instead) attempted to create the conditions which “naturally” would provoke the phenomenon.  It proved difficult and the implosion eventually was induced by artificially reducing the internal pressure.

Explosion (pronounced ik-sploh-zhuhn)

(1) An act or instance of exploding; a violent release of energy resulting from a rapid chemical or nuclear reaction, especially one that produces a shock wave, loud noise, heat, and light (or the noise itself).

(2) A sudden, rapid, or great increase.

1615-1625: From the French explosion, from the Latin explōsiōnis, a genitive form of explōsio, from explōdo (I drive out by clapping) from explōdere (to explode), the construct being ex- (the prefix from Middle English from words borrowed from Middle French from the Latin ex (out of, from), from the primitive Indo-European eǵ- & eǵs- (out). It was cognate with the Ancient Greek ἐξ (ex) (out of, from), the Transalpine Gaulish ex- (out), the Old Irish ess- (out), the Old Church Slavonic изу (izu) (out), and the Russian из (iz) (from, out of)) + plōdo (I clap or I strike).  The figurative of "going off with violence and noise" is from 1660s and some sources insist the sense of "rapid increase or development" wasn’t noted until 1953 when it came to be used in commerce (describing both the extraordinary proliferation of consumer products in what would later come to be known as the “affluent society” and spikes in demand).  In the mid 1940s, the US conducted a number of nuclear weapon tests at Bikini Atoll in the South Pacific and when asked about his choice of “bikini” as the name for the fetching swimwear he trademarked (patent #19431) in 1946, the designer is reported to have at the time remarked he expected an "explosive commercial and cultural reaction" as dramatic as one of the Pentagon’s A-bombs.  The figurative use thus dates from at least the 1940s and it would seem at least plausible that in that vein the word had been used for a long time, centuries of wars exposing millions to explosions surely likely to have inspired the linguistic imagination.

In Ancient Rome, at the conclusion of a play, the actors would turn to the audience and command plaudite! (literally "clap your hands!); that's the source of the English plaudits (a mark or expression of applause; praise bestowed) and of the idea of the plausible (something to be applauded).  However, if the performance was a dud, the audience would explodo (the construct being ex- (out) + plaudo (clap), the idea being the actors is the dreadful performance would be "clapped off then stage" and as late as the seventeenth century the phrase persisted, surviving reports from critics recording "the crowd exploded him off the stage".  Indeed, even now, phrases like "the theory has long been exploded" are still sometimes seen although whether the writer has in mind the idea or "clapped away" or "blown up" may be uncertain. 

Figurative use: Lindsay Lohan with former special friend Samantha Ronson, the photograph taken in Mexico and dating from October 2008.

In figurative use, "implosion" and "explosion" frequently are used to describe different events or phenomena, the former often related to sudden and dramatic changes and while the latter can be used in this way, implosions can be imagined as gradual things which unfold over a long time, sometimes even years.  That said, there are some “explosions” which are regarded so only because of their peculiar context, such as the “Cambrian explosion” which was sudden and dramatic only against the measure of the evolutionary history of life on Earth.  The Cambrian Period, while a relatively brief period in the planet's four and a half billion years-odd of existence still encompassed in excess of forty million years (circa 540-485 million years ago).  During this time, there was a remarkable diversification and proliferation of complex multi-cellular life forms in the oceans and it was “explosive” in the sense nothing like it had happened before and in evolutionary terms, the appearance and diversification of an array of complex organisms (including the first appearance of animal groups or phyla which remain extant) was rapid indeed.  Still, that sort of figurative use of “explosion” tends to be restricted to evolutionary biologists and their ilk and it’s more familiar when used to describe something short & sharp like the rapid acceleration of a running back on the football field.  That would be over in seconds but in sport, something like the innings of a cricketer might be called “explosive” even if it unfolds over an hour or more.  It’s all a matter of context and literal explosions tend by their nature to be fast, brief events.

Just about any dictionary would define an explosion as something like “a rapid and forceful outward expansion or release of energy”, conveying the idea of something bursting forth or erupting with great intensity, impact, or noise and that’s familiar from the event associated with impacts, bombs and even volcanic eruptions which, although they can last for weeks are really only an explosion of short duration, following by consequential events like mud or lava flows which can last weeks.  However, far away (and long ago by the time we find out), there are explosions which are on such a scale they can take months.  There are lots of stars and sometimes, they explode.  In a sense, nothing lasts forever, yet at the same time, matter is, in one form or another, eternal.  Explosions are part of this process.  Quite how many stars exist is unknown and given we can observe only part of the universe, any estimate beyond a certain point is meaningless although, given calculations based on observable data suggest that there are at hundreds of billions of galaxies, each of which probably contains millions or billions of stars.  So, estimates (guesses) vary but the fact 1 septillion (1 followed by 24 zeros) is thought credible is interesting, not for the specific value it represents but because it means whatever might be the answer, it’s a very big number.  The time it takes for a star to explode depends on the type of star and the point it’s reached in its evolution but the two most significant types of stellar explosions are (1) supernovae and (2) stellar novae.  The mechanics and time absorbed by each in their explosions varies greatly.

A supernova is a powerful and catastrophic explosion which occurs at the end of the life of a massive star (or in a binary star system) and it can take (as seen from Earth) from a few weeks to several months.  As a prelude, over millions of years, the star will undergoes various stages of nuclear burning and fusion, culminating eventually in a catastrophic collapse and explosion.  Less energetic is a stellar novae which occurs in binary systems where a white dwarf star accretes matter from its companion star.  The accumulation of matter on the surface of the dwarf can lead to a sudden and rapid release of energy, resulting in a nova explosion.  Novae typically brighten over a short period, reaching peak brightness in a matter of days or weeks, after which they gradually fade away over several months.  Not all stars end with an explosion.  Less massive bodies (like our Sun) don’t explode but kind of fade away through a process cosmologists call stellar evolution, expanding into red giants, shedding their outer layers, eventually to be become white dwarfs on the path to dark, dead obscurity.  Back on Earth, the figurative use extends from a rapid increase in popularity of someone or something to sudden outbreaks of violence by individuals or entire societies and something said or done which might induce either of the latter can be said to be “potentially explosive”.

Conversely, “implosion” is used figuratively to describe an internal collapse or inward sinking, rather than an outward burst although the latter may be consequent upon the former.  It’s suggestive of a situation or event where there is (suddenly or gradually) failure, disintegration, or decline, typically accompanied by a loss of control or power and implosions are often associated with the gradual accumulation of pressures or internal forces that eventually lead to a collapse or breakdown.  Individuals, institutions or societies may be said to have imploded because they lacked the strength, internal cohesion or resources to resist pressures which may be externally imposed, generated internally or a combination of both.  However, although both explosion and (probably more frequently) implosion are among the general population commonly used terms when discussing aspects of metal health (usually of others), they’re officially not part of the lexicon of clinicians or other professionals in the field.  It may be that the words are sometimes in their thoughts when faming a diagnosis but neither appears in the American Psychiatric Association's (APA) Diagnostic and Statistical Manual of Mental Disorders (DSM) which for decades has provided a standardized classification and criteria for diagnosing mental disorders.

An explosion: A simulation of the detonation of the Soviet Union’s AN602 Царь-бо́мба (Tsar Bomba), a thermonuclear gravity bomb which was the most powerful nuclear weapon yet built (as far as is known) or tested.  It was detonated on 30 October 1961 on a remote island in the Barents sea and the Russian claim of a yield equivalent to 50 megatons of TNT is now generally accepted (the contemporary US estimate of 57-60 was based on more remote observations).

Bathymetry

Bathymetry (pronounced buh-thim-i-tree)

(1) The science and practice of the measurement of the depths of oceans, seas, rivers or other large bodies of water.

(2) The data derived from such measurement, especially as compiled in a data set or topographic map.

1860–1865: The construct was bathy- + -metry.  The prefix bathy- (the alternative form in oceanography and related fields is batho-) was from the Ancient Greek βαθύς (bathús) (deep), zero-grade of the root of βένθος (bénthos), possibly from the primitive Indo-European gehd- (to sink, submerge) or perhaps cognate with the Sanskrit गाढ (gāḍha) (profound, intense, deep, dense, thick, fast, deep (of a color)).  Despite the appearance, it’s unrelated wither to βυσσός (bussós) or βυθός (buthós).  The construct of the suffix –metry (used to form nouns relating to measures and measurement) was -meter +‎ -y.  Metre was from the Ancient Greek μέτρον (métron) (measure), from the primitive Indo-European meh- (to measure) + -τρον (-tron) (a suffix denoting an instrument, as in ancient Greek ἄροτρον (plow) and familiar in English for the used in electronics and physics such as cyclotron.  The –y suffix is from the Middle English –y & -i, from the Old English -iġ (-y, -ic), from the Proto-Germanic -īgaz (-y, -ic), from the primitive Indo-European -kos, -ikos, & -iḱos (-y, -ic).  It was cognate with the Scots -ie (-y), the West Frisian -ich (-y), the Dutch -ig (-y), the Low German -ig (-y), the German -ig (-y), the Swedish -ig (-y), the Latin -icus (-y, -ic), the Sanskrit -इक (-ika) and the Ancient Greek -ικός (-ikós); a doublet of -ic.  The –y suffix was added to (1) nouns and adjectives to form adjectives meaning “having the quality of” and (2) verbs to form adjectives meaning "inclined to".

Bathymetry bathymetrist & bathymeter are nouns, bathymetric & bathymetrical are adjectives and bathymetrically is an adverb; the noun plural is bathymetries.  The derived noun paleobathymetry describes the bathymetry of prehistoric seas.  Paleo was from the Ancient Greek παλαιός (palaiós) (old), from πάλαι (pálai) (long ago).  Most etymologists suggest it was probably cognate with the Mycenaean Greek parajo, which is generally held to mean “old”.  If true, this connection hints at a link with the Proto-Hellenic palai(y)ós and casts doubt on the once often proposed etymology from the primitive Indo-European kwel.

In the UK, the Royal Navy's early use of bathymetric data was to add indications of depth to the Admiralty's charts, the most famous of which was the one which drew the "hundred fathom line" around the British Isles.

When coined in the mid-nineteenth century, bathymetry referred to the ocean's depth relative to sea level, reflecting the information available, given the technology of the time. In the twentieth century, it came to mean “sub-marine topography”, the rendering in images of the depths and shapes of underwater terrain.  In this it’s analogous with topographic maps of land masses which represent the three-dimensional features (or relief) of overland terrain.  Bathymetric maps typically represent variations in sea-floor relief by depicting the changes with color and contour lines called depth contours or isobaths.  Bathymetry provides the baseline data which made possible the modern discipline of hydrography which measures the physical features of a water body.  Hydrography compliments bathymetric data with measurements of the shape and features of shorelines, the characteristics of tides, currents and waves as well as the physical and chemical properties of the water itself.

Bathymetry is thus the study and mapping of the sea floor. It involves obtaining measurements of the depth of the ocean and is the equivalent to mapping the height of features on land.  Bathymetric data is used for a range of purposes including charting and ship navigation, fisheries management, establishing baseline data to support environmental monitoring, the determination of maritime boundaries, alternative energy assessments (most obviously regarding offshore wind and wave & tidal energy), research into coastal processes and ocean currents (the best known aspect of which is tsunami modelling, assessment of the environmental impact on marine geology of resource extraction proposals and the identification of geohazards, such as underwater landslides

Bathymetry map of East Flower Garden Banks National Marine Sanctuary (FGBNMS), a United States National Marine Sanctuary 100 nautical miles (190 km) off Galveston, Texas, in the northwestern Gulf of Mexico.

However, despite the progress of over a century, relatively little is known about the sea floor compared with the surface of the Earth, the Moon and indeed many of the solar system’s other planets and moons.  By area, most map of the sea floor are derived from satellites an low resolution, provide only a vague indication of water depth although whatever the limitations, the technology is clever, the satellite altimetry measuring the height of the ocean surface.  If hills or maintains exist on the seabed at the point of the image, the gravitational pull around that area will be greater and hence the sea surface will bulge and from this measurement maps can be generated showing general features over a large area at low resolution.  More precise maps can be built using single beam echosounders which produce a single line of depth points directly under the equipment.  Taken usually from a moving vessel, they’re typically used to identify general sea floor patterns or schools of fish.  More accurate, high definition maps can be generated by using devices called multibeam echosounders (or swath echosounders) and airborne laser measurements (LADS) which capture swathes of data by acquiring multiple depth points in each area, these data grabbers are accurate to within 1 metre (39 inches).  It was a bathymetric survey which revealed the world’s tallest mountain is not Mount Everest but the Mauna Kea volcano on Hawaii.  Much of its base is on the ocean floor, some 6,000 m (19,685 feet) below the sea-surface and its peak is the highest point in the state of Hawaii, giving an overall height of 10,000 m (32,808 feet).  Mauna Kea is thus a significantly higher feature than Mount Everest which rises 8,800 m (28,870 feet) odd.

Modern electronics represent quite an advance over the nineteenth century techniques of bathymetric measurement which began with a heavy rope being thrown over the side of a ship, the only data gained being recording the length of rope it took to reach the seafloor.  These measurements were however incomplete, and prone to inaccuracy, the rope often shifted by sub-surface currents before reaching the seabed.  At best the data was indicative because the rope could measure depth only one point at a time and there was no way to tell if the point of impact was flat or sloping.  Depending on the area of interest, scientists would have needed dozens, hundreds or even thousands of measurements, something obviously rarely possible.  Accordingly, until the modern age, scientists and navigators estimated the topography of the seafloor and for experienced sailors, the hills and valleys were sometimes easy to predict but the sea can be deceptive and ocean trenches and sandbars often surprised navigators.  Many ships and cargos were lost to ships running aground.