In the last episode, the titular mecha ejects its smaller forms at the enemy when it is restrained. Tengen Toppa Gurren Lagann is the size of a galaxy. Chouginga Gurren Lagann is the size of the moon. They appear in the same frame. The fact that this happens should make anybody with a passing knowledge of astronomy angry. Either the Gurren Lagann Universe has small galaxies or its planets are somehow resistant to turning into black holes.
The creators muddled this up further by stating that TTGL is "ten million light years tall". Uh, no, it's not. That figure is at least an order of magnitude off. And at Super Tengen Toppa Gurren Lagann's scale (34 billion light years, according to the creators), not only should galaxies not even be visible, but it's about a third the diameter of the observable universe. Though, it should be noted the fight happens in a parallel universe.
The Great Zamboa (the antagonist's galaxy-sized mech) has a planet stuck in its forehead. This implies the planet is light-years across. Such a planet would normally have collapsed instantaneously from its mass. Though, given that the antagonist is essentially an all-powerful deity, it's not too surprising they could enlarge their planet to such sizes.
Every single attack that the galaxy mechs throw had to go faster than light speed, or else the fight would have either lasted years or fought completely blind. Plus, galaxies are mostly empty space, like atoms; but unlike atoms, they have no strong repulsive forces surrounding them. The humongous mechs run around on a big galaxy and throw smaller galaxies at each other, which is like a pair of speeding freight trains on gaseous tracks throwing clouds of gnats at each other.
Logic was violently thrown out the window with a artillery cannon the minute they arrived in the Anti-Spiral pocket dimension. The Chouginga Gurren Lagann was shown to have transformed from a ship roughly the size of the moon, but entire planets could be chucked at it and would bounce off like beachballs (both in form and in size). The show itself lampshades how little of a donkey's rum they give about any sort of logic at that point, casually saying that the mech's shields were somehow able to deflect 100% of all damage yet still be under heavy assault from planets being flung into it, all because the Anti-spirals somehow messed around with probability.
Maybe those projectiles were not planets but meteors? Or planet-like projectiles generated by Anti-Spiral ships.
After The Team successfully pulls off yet another physics defying stunt:
The Gundam franchise has hundreds of examples of this. Most notably, the Mobile Suits are mostly made of a variation of titanium, yet they have the same density as the human body. (The original RX-78-2 Gundam is 18 meters tall and has a mass of 60 tons. In accordance with the square-cube law, it's 10 times taller and 1000 times heavier than a 1.8 meter tall human weighing 60 kilograms, which means it has the same density.)
Another example is the vulcan-machineguns most Gundam-types have. Most of them (the Gundam Ground-Type being most notable) actually have realistic sizes for their vulcans, but others, such as the Gundam Mk.II are just plain absurd. They can't expect us to believe the Gundam Mk.II has two 60mm Machineguns installed in its head. A few other Gundam-types go even further, by having 200mm vulcans in its head. That's right. Head-mounted machineguns bigger than the machineguns carried by a Zaku II.
Parodied by Usopp, who claims to wield a hammer that weighs 5 tons, but actually only weighs a few pounds.
This is fairly common in Marvel Comics. Marvel measures its characters' Super Strength based on how many tons they can lift. The problem is most people at Marvel apparently don't know how many tons a given object weighs or how much space a set number of tons of a given material will take up. Even more confusingly, Marvel's strength tiers tend to end at 100+ tons, meaning 100 tons and any number above that.
One image from Marvel Team-Up was fairly infamous in its time, even receiving a massive splash page and a really long apology from the editors in their 'No-Prize' one-shot dedicated to pointing out their own errors that readers caught. The image? Hercules, of the Avengers, towing the Island of Manhattan through the Atlantic, bringing it back into the Harbor, by means of a gigantic chain wound about himself - thus not only stating that Hercules is capable of pulling Manhattan, BUT ALSO that Manhattan floats. Oh, if this wasn't ridiculous enough, he's pulling it back the wrong way around, so that Uptown is now Downtown and the Battery is the northmost point of the island. This happened.◊
One is also given to wonder what that chain was made out of, such that it can exert that much force without snapping. And what kind of land he was standing on that he could brace his legs against it without it crumbling.
Eventually, that particular story was stated to be simply one of Herc's tall tales (the Marvel version has always been fond of them).
In all fairness, as the comic itself notes, the Hercules of legend once held the sky on his shoulders while substituting for Atlas.
Ant-Man can increase his size to beyond some kind of cosmic infinite limit, to the point where he can interact with the embodiments of abstract concepts, without first collapsing into a black hole or otherwise destroying Earth.
It should be noted that the tons lifted isn't so much an exact measurement as a point of comparison - for instance, Sif can lift 30 tons and the Thing can lift 90. Both can lift far more, but the Thing is three times stronger than Sif. Class 100+ is basically the threshold for the real heavyweights. It is also implied in both Marvel and DC that superstrength is just Tactile Telekinesis, thus getting around the density issue. Mostly.
Films — Live-Action
In Independence Day, the mothership is stated to be "over 550 kilometers across, and in terms of mass it's a quarter the size of the moon." Later images of the mothership showed it to be hemispherical. A 550 km diameter hemisphere, with 1/4 the mass of Earth's moon, would have an average density of 1687 grams per cubic centimeter. That's nearly 150 times the density of solid lead.
Such a mass in close orbit around the earth would create massive earthquakes, storms and other weather phenomena.
Interior shots of the mothership showed it to contain mostly empty space. This means that if its average density is 1687 g/cc — an average that would have to factor in the density of all the empty space — the actual density of its structural materials must be much, much higher. The mothership must be made out of white dwarf matter or neutron star matter.
There's also the question of why the Air Force would shoot air-to-air missiles at the kilometers-across city-destroyer ships. Those things are not used on aircraft carriers, let alone a ship the size of a small city, they're used on other planes. Did the writers think the Air Force wouldn't notice the thing that shades most of a city-center is just a bit larger than an airplane?
In Star Trek IV: The Voyage Home, they had to warp the ship around the sun, and relating the scale of ship and the sun, the sun would be only smallish world sized!
The narration in Water World begins with: "The polar ice caps have melted, covering the Earth with water." Even if the entire arctic ice cap, and the ridiculously huge antarctic ice cap, were to completely melt, the extra water would only cause the sea level to rise some 200 meters. That's more than enough to flood all existing coastal regions, but it wouldn't begin to cover even the shortest mountain range, let alone bring the ocean to within a few meters of the top of Everest as shown at the end.
Add to that the fact that the polar ice caps didn't form in the first place until comparatively recently in Earth's history (well after the dinosaur extinction at the end of the Mesozoic), and the implausibility becomes readily apparent.
The Death Star is likely an impossible structure, and this response to a petition made to the White House suggesting that one should be built explains why. (The rest of the response simply mocks the absurdity of the petition).
The trope is played very straight in Return of the Jedi, where the second Death Star is under construction in an impossibly low geostationary orbit above the surface of the moon of Endor. If nothing else, the enormous mass of the station so close to the Moon's surface should have caused major environmental disturbances. To say nothing of what would have happened when the Death Star exploded....
Oblivion (2013): Even if cracking the Moon caused massive tidal waves and earthquakes, there wouldn't be enough sedimentation to completely bury New York up to the Empire State's observation deck.
In Alien lore there is the infamous "wooden planet" concept for Alien³. Despite having a diameter of one mile only (that manages to look even smaller in concept art) and being made entirely of, you know, wood, the "wooden planet" was supposed to have a "shallow atmosphere" and in consequence a gravitational field to hold it together that was presumed to be artificial. The Moon, with over 2100 miles of diameter, is too small to have an atmosphere; Mars, twice that size, had an atmosphere once that it lost for, again, being too small to retain it in the long run.
Despite containing one of the vanishingly rare aversions of distance and speed issues in military sci-fi, David Weber's Honor Harrington did suffer "The Great Resizing" as a result of the author forgetting the square-cube law while assigning the lengths and masses of his setting's starships. When the people trying to create a gaming spinoff crunched the numbers, they realized his smallest ships were about right, but the mightiest warships were "not quite as dense as cigar smoke!"
Since the text makes only rare references to length, and very commonly notes mass as a determinant of acceleration, the author retconned in a new and much shorter length that delivered reasonable density.
Weber does it also in his story Mutineer's Moon and sequels in the Empire from the Ashes series, in which the starting premise is that the Moon (i.e. Luna, Earth's natural satellite, that Moon) is actually a starship. Yes, the whole thing. It has a layer of rock around the outer hull carefully sculpted to match the surface appearance of the original Moon that once orbited the Earth, tens of thousands of years ago, before the starship removed it and took its place. Incidentally, the entire human population of the Earth in these books descend from the human crew of that starship.
At no point does Weber write the ship as if it was 2,000 miles in diameter, though, nor is it ever seriously explained why it needs to be that big. He writes the starship as if it were a few miles in diameter.
The book does state that the type of FTL engine used and the reactor to power it (as well as the Hyperspace Radio) all reached optimum efficiency only when scaled up to planetoid dimensions. To give you an idea of just how much power their reactors put out, it took only six Battle Planetoids working together to force a star to go supernova.
Given the information presented in the books it's entirely possible that the living areas of the ship are only a few miles across with the majority of the ship being dedicated to weapons/propulsion/power systems etc. It still seems unlikely that such a large unit is really worth the resources (especially when it's demonstrated that smaller war ships can be FTL capable).
All There in the Manual Dahak and the other planetoid sized ships were built in order to defend against the next genocidal attack by the Achuultani, so they'd want them big, not only so they could stuff in as many weapons as possible, but to take a pounding as well. Given that ships like Dahak were intended to be deployed on picket duty for years, if not decades, they built the crew quarters with comfort in mind. You also need to take into account the hangar decks for the sublight ships. The volume isn't really wasted, and it turns out to even have something of a psychological effect; the aliens are terrified by the sheer size of the planetoids.
Larry Niven's Ringworld takes the common misconception about the Dyson Sphere (see below) to a more 'practical' level. Why build a sphere around a star when a single continuous strip could house more life than could possibly fill it? But the example of this trope comes more into play with The Ringworld Engineers, which was written after Niven attended a convention where several college students were roaming the halls chanting "The Ringworld is unstable". Niven did the math and, nerds being nerds, discovered they were right. The Ringworld is indeed unstable, so he added some jets to allow it to maintain its position.
Ringworld starts off with the Puppeteers fleeing the galaxy, dragging the five planets of their home system with them, which has its own host of Sense Of Scale problems (The planets have massive reactionless engines that are accelerating the who group through controlled gravity, which probably involves some energy issues, but is much less goofy than it sounds at first.)
Also by Niven, in his Integral Trees setting: the so-called "integral trees" are plants in a free-fall environment typically between 50 and 100 kilometers long and 700 meters across. A small (few thousand people), fairly primitive (early Iron Age) society is harvesting these trees for lumber at an implied rate of one or two a year. Thing is, a single tree will yield about eight trillion board-feet of lumber, or about a century's output of the entire United States lumber industry.
Stephen Baxter's Ring features an artificial ring the size of a galaxy spinning at something close to the speed of light, with the idea its sheer mass would rip open a hole to another universe. The enemies of the ring-creators are peeved at this and hurl entire galaxies at the ring (including ours, but it's okay as we won't get there for several tens of billion years) in an attempt to destroy it, to no avail. The plausibility of such an object's size and the ability to build it without either exhausting all matter in the universe or getting it finished before the end of time may depend on the reader's suspension of disbelief.
To be fair, the ring-creators came into existence a couple seconds after the universe did, are born in black holes, have utterly ridiculous technology, and have a stable time-loop existence so that as soon as they came into existence, they were at their technological peak. They've had plenty of time.
In fact, the Ring took no less than 10 billion years to build, and they exhausted the materials of multiple galaxies to do it. But, these are the Xeelee we're talking about here, so cut them some slack.
And for all that, it sort of is the end of time (still-burning stars are starting to become scarce) before it all comes to fruition.
Much worse is Orion Rock in Exultant, an asteroid said to be travelling a thousand years before reaching the black hole in the center of the galaxy. That's all fine and well, until a protagonist standing on it gets to see molecular clouds disappearing upon reaching the rock's destination. That means that the cloud is several orders of magnitude denser than any nebula ever known (probably around the density of water clouds), and that it has an impossibly crisp edge (going from that insane density to zero in only a few hundred kilometers tops).
Anne McCaffrey's Dragonriders of Pern: If we go by the measurement system provided by the books and supplemental materials, the Queen Dragon Ramoth at 45 meters from nose to tail would be only slightly smaller than the Lockheed Tristar, a passenger jet capable of holding around 250 passengers (which is used as the example in the supplemental books), making her the largest animal ever, and the other dragons are no slouches either. Bronze dragons which are the only ones "allowed" to mate with the golds range from 30 to 42 meters in length. And all of these dragons only get one Rider. There's a reason why the fan roleplaying communities tend to believe that "meter" is a mistake and use the foot instead, making Ramoth only slightly larger than the Tyrannosaurus rex, which was not the largest animal ever on Earth, which makes it a lot easier on an environment by not having several hundred carnivores exceeding 100 feet in length devouring what are essentially Earth cows.
And then there's the Hand Wave that a dragon weighs only as much as it wants to and can carry as much as it wants to being a result of their telekinetic powers which only get discovered in one of the last books chronologically.
Andre Norton describes the Free Trader ship Solar Queen as both "small" and "needle-slim." It's also clearly a rocket shape. But when she explains the accommodations on a single deck within that "small" hull, it's clear that to have "needle-slim" proportions at that size, it'd need to be about the height of a Saturn V.
Ship sizes in Andrey Livadny's The History of the Galaxy series can be a little off, at least as described on his website. From 20-meter one-man Space Fighters to 7-kilometer flagship cruisers, crewed by 150 people. While the author tries to explain it by having most systems be automated (in fact, entire ships can run without crews, using only AIs), this does not explain why the ships have to be so ridiculously big. Interestingly, one novel specifically mentions a heavy cruiser (about 5 km in length) with a crew of 2000. However, even that is an extremely-low number of people to run a ship this size. For reference, a Real LifeGerald R. Ford-class aircraft carrier will be about 333 meters in length and have a crew of 4660. This is not even to mention the stress of trying to maneuver a 7-kilometer beast in battle. The only thing the author got right is that any ship larger than 500 meters is unable to enter planetary atmosphere without assistance from technical carriers (i.e. tugs). Even corvettes, which are 500 meters long, come equipped with additional planetary engines to allow them to survive re-entry.
Possibly a case of Realityis Unrealistic if we are to treat the Space Navy as a contemporary wet navy. This is due to the fact that ships of similar size and class of successive generations have a much smaller crew then previous ships of their type, so it is plausible that massive ships of the future in space could be crewed with orders of magnitude greater volume then crew. All ships are meant to be operated by the least ammount of people who can do the same job an optimal levels, so as Technology Marches On it's to be expected.
Another example showing how you can screw up sizes without going into space comes from Edgar Rice Burroughs' Pellucidar. One scene has a lidi running in terror when pursued by two hyaenodons. The hyaenodons are described as being as large as ponies. The lidi is a sauropod dinosaur, 80-100 feet long. This is the equivalent of a pair of rats chasing a horse, or a pair of foxes chasing an elephant (this is one of many instances where Burroughs shows his total lack of understanding of animals).
A Song of Ice and Fire author George R. R. Martin was confronted with a failure of his own sense of size when he was shown the videogame adaptation of his book and noted that the great wall guarding the north was huge. On being told that it had been scaled precisely to his description in the books (approx. 700 feet tall), he replied "I wrote it too big!" The construction can be hand-waved as A Wizard Did It, but it remains jarring to imagine people interacting with such a structure day-to-day.
Other buildings suffer the same problem, with the lighthouse/stronghold of Hightower being slightly taller than the Wall and the Great Pyramid of Meereen being 800 feet tall... and a pyramid into the bargain. If it had similar proportions to the Pyramid of Giza, it would have a footprint 1500 feet to a side, or 50 acres.
This official picture has been endorsed by Martin himself as the depiction of the Iron Throne closest to the one in his mind. In one memorable event in the backstory of the series, one of the white knights bellow sits on the throne (not the stairs at its base) because he is just too tired and needs to sit down for a moment, and is found there by the hero. So... was he too tired to stand on his feet but not tired enough to climb a two-stories-house worth of stairs?
Iain Banks addresses the Dyson Sphere problems with his "orbitals" - ring-shaped worlds that are only five million kilometres across and in a conventional orbit about their star. The size is chosen so that one revolution per standard day evokes one standard gravity of centrifugal force. In Consider Phlebas there is passing mention of Spheres and Rings, but by later novels they seem much less popular (probably because having decided to give the Culture's total population at ~18 trillion, it's immediately clear that even one such structure is unimaginably more than they could ever possibly need).
Matter is set on a "shellworld", effectively a planet-sized (and shaped) set of matryoshka dolls. The one in the book has 15 levels, coming to 11.8 billion square kilometers of space.
The Morthanveld (a Culture equivalent Involved) Syaung-un nest is absurdly huge. A donut made of water tubes (Morthanveld are aquatic and don't like things they can't see through) of diameter 300 million kilometres and thickness of over a million kilometres for a population of a mere fourty trillion? To see how absurd this is reduce the volume by a factor of a trillion: Is a donut 30 thousand kilometres in diameter and 100 kilometres thick appropriate for a population of 40? No? Then neither is the original size. Even a conservative estimate of it's mass (assuming lots of empty space between these up-to-10km-thick tubes) would put it's construction as requiring taking apart every planet, comet and asteroid in a thousand solar systems. It doesn't fit at all with the normal size of Involved engineering projects (especially the absurdly tiny volume of the entire Culture warfighting forces).
In the Grand Finale of Smallville, Apokolips is first shown to be similar in size to, if not larger than, Saturn, but when it comes to Earth it shrinks to the rough size of Metropolis.
The Star Trek: The Original Series episode "The Galileo Seven" in which Spock and a small crew were lost in a shuttlecraft while the Enterprise studied "quasar-like phenomena." The image on the main screen was clearly of an artist's rendition of a quasar. Today, we know that a quasar is the supermassive black hole at the center of a very young galaxy, spewing enormous amounts of energy as material falls into it. The implications are either of a galaxy-like phenomenon within a galaxy (?!), or that the Enterprise was at the far reaches of the universe studying a quasar with a very, very small number of worlds therein.
It should be noted that no-one knew for sure that a quasar is a galaxy until the 1980s, and they don't look like one without additional information that wasn't available when the episode was made. Therefore this is more a case of Science Marches On.
Yet even at the time the episode was made, we knew that quasars had enormous redshift, implying that they were extremely distant phenomena.
Hilariously, the remastered version added stumpy little relativistic jets and an accretion disc.
Which could make this Fridge Brilliance, as studying a star-mass black hole that emits energy like a true quasar would be the best way for the Federation (which lacks intergalactic travel) to learn about the full-size versions.
The episode "The Corbomite Maneuver" has the Enterprise encounter a mysterious cube, which Sulu says is 107 metres on each side and masses just under 11,000 metric tonnes. Scotty says it must be solid metal, leaving him wondering how it could be powered and how it moves around. But the quoted measurements give a density of about 9 kilograms per cubic metre, significantly less than styrofoam - implying the cube is almost certainly hollow (they may have been aiming for 9 tonnes per cubic metre, which is between the densities of iron and lead, and dropped a factor of a thousand somewhere).
In at least one episode of The Next Generation turning off life support for five minutes was enough to exhaust the entire oxygen supply of the ship. Considering the absurdly spacious rooms, they should have lasted quite a while longer.
As a side note, the greatest danger in such a situation is not oxygen running out, but the level of carbon dioxide in the air reaching toxic levels. Still should've taken hours at least with that much space.
Used intentionally and cranked up to 11 via the Rule of Funny in Psych, where detective Shawn Spencer has to pretend to be the guide doing a laser light presentation at an observatory, but quickly makes it painfully obvious he knows nothing about space.
Shawn: There are almost 4... hundred stars, in our galaxy. Maybe more. No one knows for sure. Some say that the Milky Way may be larger than the Indian Ocean. Ah, and here are our constellations. Here's one of a fish...and here's one of a guy, holding........ some sort of a thing?
Janitor: (whispering) You're supposed to name them!
Shawn: And here is Monkey with Rash. The Egyptians used to set their clocks by it. And here is the Hammer of Jeff.
The Doctor Who episode "Partners in Crime" was guilty of this. Early on, it's established that an Adipose is created from one kilogram (about 2.2 pounds) of fat. The average person weighs about 70 kilograms (159 pounds). When a character gets totally converted into Adipose (ignoring the other problems this causes), only about 15 or so Adipose are created, apparently preserving volume, but dumping over half the person's mass. Although a human's body does not contain anywhere near 100% body fat...This chart shows that an average person's bodyfat percentage is about 20-30% — and 15 Adipose = 15kg out of 70kg bodymass = 21.5%. Which is quite plausible, so it just leaves the question of where everything else goes..
In "The Daleks' Master Plan", the Daleks form an alliance with the rulers of several galaxies for the primary purpose of conquering the Solar System. Putting aside individuals claiming to rule entire galaxies, multiple galaxies joining up to conquer a single star system is nothing less than massive overkill. A throwaway line suggests the Hand Wave that Earth exhibits influence beyond its normal sphere, but militarily it's never described as anything but the "Solar system."
While the writer states Earth physics don't mean a thing in BIONICLE, scale issues come up frequently. There's Mata Nui for instance, a circa 40 million feet high robot with a whole ecosystem inside him, who was build under a fairly short time, standing tall on the surface of his planet, in secret. His prototype, which was two thirds his size, blew up shortly before his construction, and none of the planet's inhabitants seemed to have grown suspicious of the mountain-sized robot parts that rained around them, all over the planet. Then, when these two bodies fought 100,000 years later, it was explicitly stated that the other, normal-sized characters simply ran around under their feet, crossing distances of thousands of miles within minutes. In the Mata Nui Saga, this scale issue had been taken into consideration, but they simply decided that the Saga's illustrations should depict both the giant robots and the human-sized characters within the same image. Otherwise, we would have only seen either the giant mechanoids duking it out alone, or the armies of the "regulars" clashing in front of a gray backdrop.
Another example: the Mata Nui robot's mission, according to his hastily written backstory, was to study other civilizations and learn how to prevent wars. He did so by approaching a populated planet, lying down into an ocean, and covering his face with an artificial island. After thousands of years, he would rise up and continue his journey through space. Disregarding the fact that his massive chest would probably still have protruded through the water, just how does a robot as tall as Earth is wide lie in a body of water without anyone noticing, without raising water levels, or without simply having any effect on the planet itself? The Mata Nui Saga took a more reasonable route and depicted Mata Nui gathering information from civilizations through his special powers, while staying clear of any planet.
The most obvious problem is the various "maps" you can see of the various "Nui" islands within Mata Nui. They're arranged in such a way that it looks plausible as being contained inside a humanoid, but unless massive scaling is in order there's no possible way these would fit in the body we saw, especially with the scale. To say nothing of the character's journeys.
In the Wild Talents 2nd Edition superhero setting, one of the suggested campaign seeds is being part of an exploration team for a defunct alien "world-ship" that has moved into the solar system. The campaign text says, explicitly, "Every square inch of the 'ship', 6,123 miles in diameter, was to be searched under the express orders of Joint Space Command." This is a volume of over four billion trillion cubic meters they are talking about here. If the entire population of the planet Earth, all six billion people, were used for a search team, each person would still have to search over 660 billion cubic meters. Hope they packed a lunch!
...or just had a Talent specializing in investigation onboard, who could probably do so in a few minutes. This is a setting where teleporters routinely send space installations to Mars, gadgeteers mass-produce giant robots, and the World Ship and its inhabitants were possibly subconsciously wished into being by a suicidally despondent Talent, searching a ship that size in a timely matter isn't that unlikely.
In the Progenitor setting for Wild Talents, the first superhuman was infused with 1% of the universe's Dark Matter energy. While obscenely powerful by supers game standards, her powers aren't anywhere near, say, Gurren Lagann level crazy, much less Bronze Age Superman crazy.
In Battletech, a large Dropship weighs ten thousand tons, and is protected by 30 tons of armor. Considering it's a hundred meter sphere, it comes to the ship being about fifteen times as dense as air, and the armor being paper thin. Most of the mechs have the density of styrofoam - the Atlas is a 100 ton mech that is something like 18 meters tall. A stiff breeze would blow them over. Additionally, the mech's mass would cause them to sink through paved concrete roads as they have a relatively small contact area with the ground - while in the case of the Atlas, it's a fairly large area due to its ginormous feet, and yet some mechs have pencil-thin feet.
On the other side of the scale, the Star League-era Rotunda scout car (a combat vehicle disguised as a luxury sports car or any other civilian vehicle and armed with a Large Laser) has its official gameplay stats list it canonically with a weight of twenty tons. While this is fairly light by combat vehicle standards, this is far, far too heavy by civilian road and traffic standards: twenty tons is 40,000 lbs. A rail car loaded empty is typically 30 tons. The Rotunda apparently has the weight of a road train (multiple trailer semi).
Gary Gygax must never have actually handled real swords before creating Dungeons & Dragons. The 6-8lb longsword found throughout the series is utterly ridiculous and would be virtually unusable. For comparison, a Real Life longsword (the actual two-handed sword, not the chronically misnamed single-hand arming sword) will usually max out at around 3lbs, often even less than that. Even the large zweihanders of the later medieval period seldom reached 6lbs. Although swords that approach the weights of those in the games do exist, these are all ceremonial weapons intended solely for display purposes, and would never have been used in combat.
Warhammer 40,000, in particular the Rogue Trader RPG, suffers from this with regards to the various space ships.
Specifically, they scale the mass - and crew - linearly with the length of the ship. As a result, while the smaller ships are reasonable enough, the larger ships end up with the density of papier-mâché (less, actually) and a vanishingly small crew.
Most solid-projectile weapons in Dark Heresy can be matched to a real-world counterpart with a similar weight, but shotguns are much heavier than they ought to be; modern combat shotguns generally don't weight more than four kilograms, while a Dark Heresy double-barrel shotgun (possibly the lightest and simplest possible design) weighs five.
The planet Zebes in the Metroid series is given a mass of 4.8 Trillion Teratons, or nearly a thousand times the mass of Earth. This is well over twice the mass of Jupiter. Sort-of justified in-universe by the planet being composed of Urithic Ore but this still raises serious questions about how such a massive planet can host the kind of life we see on Zebes. Several other planets have similarly huge masses.
Super Mario Galaxy is very confused as to what constitutes a planet or a galaxy. For example: the smallest "planets" are maybe thirty feet in all directions, and the biggest are smaller than the Earth's moon. Meanwhile, "galaxies" are simply clusters of these "planets" or sometimes just one relatively big "planet," with no stars to speak of. Unless you count the abundant tiny black holes. It can be chalked up to Rule of Fun, though, the setting running on cartoon physics.
Though the actual reason is that in Japanese, the same word is used to refer to planets, asteroids, galaxies, etc., the real confusion being why that was kept in the translation.
Probably to keep with the natural progression of things. Super Mario Land, Super Mario World, Galaxy was the next logical step.
The weapons in Deus Ex are ridiculously heavy. The Dragon's Tooth Sword, for instance, weighs about 20 pounds. For the uninitiated, a normal katana weighs about 3.8 pounds. In addition, the pistol is 10 pounds in weight and the wrist-mounted mini-crossbow is 15 pounds.
Homeworld is ridiculously bad about ship weight. Most ships' weights in "tons" correspond to them being lighter-than-air craft. I guess that would make getting 'em into space pretty easy, though.
Halo is just as bad: while the games give no numbers, the novels cite insanely light weights for ships. The 480'ish meter long titanium armored frigate for instance is given a loaded mass of just 4,000 tons. Some rough math says that this results in a ship that's not quite lighter then air, which is about 1.2 kilos per cubic meter, but seeing as the frigate works out to something like 1.8 kilos per cubic meter it's damn close. It gets even more insane when we consider that the ship is supposed to be armed with a main gun that fires 600 ton slugs.
More fun! Doing the math from Halopedia, which gets info from the novels, the Orbital Defense Platforms fire 3,000 ton slugs at 60% light speed. This results in a projectile that has 11.62 teratons of kinetic energy. That's 11,620,000,000 kilotons. For reference, the bomb dropped on Hiroshima had an energy yield of 15 kilotons or so, which makes that one slug over 774 million times as strong. For more realization of how ridiculous this number is, take the total energy consumption of the United States in 2005. Each one of these slugs, fired once every five seconds, contains about 467 times that amount.
This seems to have been disregarded, seeing as it came from the notoriously unreliable Halo Encyclopedia. Now it's generally agreed that the Fall of Reach was correct, and that the slugs are fired at 4% the speed of light rather than 60%. Which is still completely ridiculous.note The slugs mass 3,000,000 kg, so getting one of them to 4% lightspeed in 5 seconds requires over 7 teranewtons of force. It would've made more sense to make the slugs smaller, as little as a few kilograms, and left the speed at .6c—getting a 10 kg projectile to that speed only takes 360 meganewtons, and yet it hits like a 40 megaton nuke.
The Large Hadron Collider has literally 1/30th of the acceleration of the Super MAC. You're not stripping iron atoms from the slug, you're literally stripping protons, electrons, and neutrons apart. We're talking absolutely retarded amounts of acceleration here. Oh, and these things work on broadcast power. The UNSC is firing exawatts of energy at these Super MACs. At all times. They should be instantaneously vaporizing from their power source. Which, by the way, would probably be the best anti-Covenant weapon in all existence.
Then there's the SPARTAN-IIs' MJOLNIR armor, which weighs half a (short) ton, or 454 kg—each Spartan weighs as much as a horse. It's never explained how they don't sink into soft ground or destroy every ladder and staircase they use. Not to mention how awesome the suspension on Warthogs must be, they don't even lean over when the Chief gets in.
For comparison, a full suit of Renaissance plate armor weighs about 20 kg, and covers roughly as much of the body as MJOLNIR armor does. Actually, MJOLNIR plates are much thicker—possibly enough thicker to account for the difference of mass, especially if they're denser than steel. Or Bungie may have been thinking in terms of hard diving-suits; the US Navy's HARDSUIT 2000 ADS is only 18 kg lighter than MJOLNIR armor, albeit much bulkier. Still doesn't explain how the Spartans can use facilities designed for people who are only wearing 10 kg of modern-style body armor.
Sins of a Solar Empire is surprisingly good about this, although planets appear only a few times smaller than some suns. The ships are comparatively massive compared to fighters, which are so tiny they have to have markers pointing out entire wings of them if you zoom out enough to view just one capital ship.
Pokémon sucks with Pokémon weights. A Wailord weighs a paltry 398 kg, despite being 14.5 m long. For comparison, a sperm whale can be 12 to 18 m long, and weighs more than 20,000 kg.
In this case, Wailord is based on light-than-air vehicles like dirigibles and blimps. This appears to be on purpose, since Snorlax is 1/7th the size but also 1.5 times as heavy.
It also really sucks with Pokemon sizes in general, since with a few exceptions, most of them are literally a quarter of the size you'd expect such an animal or object to actually be. Like how three of the Pseudo Legendary dragons (Dragonite, Salamence and Garchomp) are between 4 and 7 foot tall. They're likely supposed to be pretty huge. Or Tyrantrum, which is apparently an 8 foot tall Tyrannosaurus Rex.
Onix, a giant snake made of boulders, is light enough to float in water.
EVE Online is a major offender in the density department, with ships averaging the density of styrofoam.note Roughly 30 kg per cubic meter.
Also, when looking at the description of a gate, its stated mass is "5e+35 kg." For comparison, Sol's mass is approximately 1.989e+30 kg, making gates over 250,000 times as massive as the Sun itself. They also create and maintain stable wormholes between two star systems. Maybe the sensors can't really determine the actual mass (which has to be relatively low, since they were carried to their positions using STL ships).
The beacons scattered throughout the universe. They weigh 1 kg and have a volume of 1 cubic meter. While actually an acceptable size, coupled with their low weight they are less dense than air! Seriously. Atmospheric air has a density of 1.2kg/m3. Interstellar beacons have a density of 1kg/m3. That's 16.67% lighter than air. At least the chances of one of those crashing down on a planet is very small.
Weather-balloons, which are similar to space beacons in many ways, have a lower average density than air (that's how they work). No reason to have a space-beacon be a weather-balloon, admittedly.
EVE just gets ridiculously jarring in this department at times. Especially with the asteroid belts. It's actually possible to sit in a belt between two asteroids that are big and dense enough to have their own gravity-wells in a ship with a density equal to something like Papier-Maché, and not be ripped apart by the two gravity-wells.
Titans have a density equal to that of aluminum, while Rifters have a density equal to that of solid gold. Who made up these numbers again?
Ships have incredibly small storage capacity compared to their size. Some ships have less proportional storage capacity than ocean going vessels use for supply closets. What makes this worse is the existence of jet cans, small pressurized pods that can hold far more than any sub-capital ship in the game, yet can be launched into space by any ship.
Destroyers, the smallest FTL-capable starships, are around 30 meters in length... Seriously? For reference, the Space Shuttle is 56.1m, while the F-15 Eagle is about 19m.
The assault shuttles are even smaller, at about 10 meters in length. And these are actually supposed to enter and exit the atmosphere (and don't look aerodynamic enough for that).
There is also the problem of a Zuul slave disk that is, maybe, 60 meters in diameter being able to hold 50 million people.
Cruisers only mass double-digit thousands of kilograms, dreadnoughts triple-digits. This is far, far too light for a craft meant to operate and fight for months to years away from port. The Airbus A380 is almost 600,000 kg at maximum take-off weight and definitely doesn't store the supplies for such mind-numbingly long operations. Furthermore, this doesn't even take into account armour - The Deacon's Tale establishes that assault shuttles use ordnance of a few kilotons and even this is inadequate to damage combat starships, implying that even harming a SOTSverse ship is a job for strategic arms. A later battle confirms that the Padded Sumo Gameplay is lore-compliant. There is no real-world material that offers this certifiably miraculous level of protection at this ridiculously low mass.
So apparently you can build a ship in the Space Empires games that's 1,350,000 tons but can carry over a billion people. A person averages 70 kilograms, and there's 1000 kilograms in a (metric) ton, so a billion people masses 70 million tons. Even if the 1,350,000 tons is the "empty" mass, most vehicles' loaded mass is not over 98% passenger.
It was initially averted in Star Trek Online and then played straight. They tried to keeps things at their canon measurements but they look so puny in the game that they made a lot of them bigger.
In Cookie Clicker, the message that pops up once you obtain 100 million cookies is "The universe has now turned into cookie dough, to the molecular level." 100 million cookies is barely enough to satisfy the United States' consumption of cookies for one day alone, let alone account for the mass of the entire universe.
Kirby has an official height: 8 inches tall. Fine, hamsters like Rick can easily be that size, as can owls like Coo. But what about Adeleine, the young human girl? And Kine, the sunfish? Doesn't that make them really small for their species?
In the various continuities of Transformers, various transformers could change their size and mass. To give you an idea on how much of a change they could make, you could pick up and carry around Soundwave and his assorted Casseticons. (The fact that they turn into a cassette player of some kind and its associated cassettes is another quandary.) Soundwave in his robot form is something like a 30-foot-tall heavily armed and armoured war machine.
Probably the worst example of this - worse even than Megatron and his gun transformation - was Reflector. Each one only slightly shorter than Soundwave, THREE robots (Spectro, Spyglass, and Viewfinder) managed to each form a different part of a camera that has been portrayed as small enough to fit into Thundercracker's hand.
On the other end of the scale is Unicron. He is a Transformer the size of a planet. And picks up another, normal size Transformer between his fingers and drops him in his mouth. To say nothing of the rest of the fight scenes against him.
The Transformers Wiki has a page dedicated to the wackiness of Transformer scale. Included is a diagram demonstrating, on the basis of his size relative to Unicron, that Galvatron must be approximately the same size as Great Britain.
The size of Cybertron itself varies a lot in Transformers lore. Considering its inhabitants tend to be about 30 feet tall, it could be assumed that the planet is fairly big, but in fact when it gets knocked into Earth orbit (which happens twice in the series) it appears to be about the size of our Moon. Considering that Cybertron is apparently too big for Unicron to consume in planet mode, this means that the actual number of planets Unicron can consume without ripping them apart with his bare hands (which in the case of a planet like Earth would take a long time) is fairly limited.
Cybertron in the Transformers film series, when shown in Earth's orbit, is actually much larger. Given that it appears to be entirely metallic in composition, it would also make it much more massive, even if its outer layers have many hollow areas. This causes problems of its own, as they appear to be teleporting it right on top of the Earth (like, closer than the Moon). Two planet-sized and massed object, that close to each other, would surely rip each other apart. Only a small portion of the planet gets teleported over, but still, you have to wonder what the hell Megatron was thinking.
Even more confusion: in the Armada anime series, Unicron is said to have been biding his time, disguising himself as one of Cybertron's moons!
The use of size-changing is often justified by character necessities: as a general rule, combiners are bigger than regular Transformers - and what's more, their component pieces have to fit together, even though a space shuttle will be much bigger than a cement truck. There's also the fact that as The Hero, Optimus Prime has to be large and imposing, but also has to transform into a truck (Peterbilt 379: 40 metres maximum). When Michael Bay mandated 'no size changing' for the movies, this meant that the normally spindly Starscream, who turns into an F-22 jet (roughly 19 metres by 15 metres), was shaped more like a buff footballer so he wouldn't tower over Megatron and Optimus.
On an episode of the 2003 series of Teenage Mutant Ninja Turtles, the entire city of Beijing is lifted into the air with alien technology. A view of the floating hunk of rock (significantly thicker than the Earth's crust) looks like the view out an airplane's window, with farm patterns visible below. A scientist states that the city is floating 20 miles above the ground, yet the city is easily 100 times its own height above the ground.
In Jimmy Neutron Boy Genius, Jimmy uses Goobot's Shrink Ray to render himself "planet-size", but this is only, at most, a few hundred feet in height.
Freeman Dyson's idea of the Dyson Sphere, a system of orbiting solar power satellites meant to completely surround a star and capture most or all of its energy output, when typically misrepresented by journalists and sci-fi writers as a solid shell completely enclosing its star. Hear that sound? Yeah, that's the collective groan of every engineer on the planet doing a coordinated Face Palm at the sheer impossibility of a solid structure of that magnitude keeping itself intact. Plus the issue of where one would get enough material to build something that would outmass the solar system it's supposed to hold several times over. Dyson himself had a sense of scale, was fully aware of the impossibility of a solid shell and had in mind "a loose collection or swarm of objects travelling on independent orbits around the star."
Cricket magazine had an even worse example in one of their stories. Not only was there a solid Dyson Sphere, but "a small strip around the equator was far enough away to support life."
The Star Trek: The Next Generation episode "Relics" featured a Dyson sphere with land, water and a sustained atmosphere (judging from all the green) on the entire inside surface. Despite the fact that the surface had open doors.
Even if you could build a solid Dyson sphere, nothing would "stick" to the inside surface, because there is no gravity gradient inside a hollow sphere. Nor would the sun have any particular reason to stay at the center of the sphere.note Though, Star Trek does take place in a setting with cheap artificial gravity.
To compound their sins even worse, there is a visible curvature to the surface of the sphere as the Enterprise passes through the door — on a sphere with about a 100 million km radius.note That's about 2/3 the Earth's orbital radius; apparently it surrounds a smaller and weaker star. To their credit the episode does say the structure is impossible. Or should be since it does in fact exist in their reality.
Receives a lampshade in Schlock Mercenary, where aliens who habitually make Dyson spheres of a canvas-like material kept inflated by light pressure from the enclosed starnote still pretty significant work structurally, but not beyond that universe's tech base have a nickname for it that translates as "This was expensive to build." note Or more literally translated, "Expensive, expensive, expensive *BLEEP* we built."
In the Star Trek novel Inferno (book three of the Millennium trilogy) O'Brien is trapped in a Pah-wraith hell featuring a solid-shell Dyson sphere. The sheer impossibility of the thing slowly but surely drives him insane. Being an illusion the whole time, it gets a pass on any sort of physical possibility.
The vast majority of giantessfap fics will have the girl end up at something like 1000 feet tall. That's more than a third the size of the world's tallest building.
For years, the assumption among paleontologists was that Quetzalcoatlus, a pterosaur with a thirty-foot wingspan, long limbs, and a long neck to match, weighed less than a hundred kilograms, or not a whole lot more than a human. This is how big they were. It's not at all implausible that something much heavier than the original estimate can fly, and then we can have had animals tall enough to look giraffes in the eye without having their interiors be blimps.
Part of the problem was that until Mark Witton started doing images such as the one linked to, most recreations of pterosaurs didn't have them in context with anything humans could instinctively relate to. Seeing that image and one suddenly realizes the 100kg (220lb) estimate is completely absurd.
"Mining ore from alien planets" is arguably this trope, with dozens of examples across all media (for instance, it's what the prawns in District9 did for a living, and it's what the Anunnaki in Zecharia Sitchin's Ancient Astronauts theory bred humanity for). A spacefaring species not composed of morons would mine from asteroids, not planets. A number of precious metals with lucrative industrial applications are hard to get because their density makes them sink toward the center of a body, and planets are thousands of kilometers in diameter. Asteroids are at most hundreds of kilometers, and often just dozens. (This is related to the all-too-common device of flying through a cometary belt made of ice to steal water from an inhabited planet—"habitability" is really the only reason you'd bother with other people's homeworlds, except perhaps for the petrochemicals that only form on life-bearing worlds.)