226 votes
Accepted

What could people notice about someone who is two times as dense as a regular person?

They can't swim. Normal humans are just barely buoyant enough to float in water. We need to generate some hydrodynamic lift to get far enough out of the water to breath. The average human body has a ...
Philipp's user avatar
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174 votes

If the Romans found one working steam engine would they have been able to copy and use it?

If a civilization finds an example of advanced technology, can they learn to duplicate the technology? You have two variables: The current technological state of the civilization. Call this "A." ...
JBH's user avatar
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157 votes
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How could an ancient race warn the future in a universally understandable way?

This problem has actually been considered very seriously by very serious people, in the context of warning future generations of the dangers associated with long-term repositories of nuclear waste. ...
AlexP's user avatar
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126 votes
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Making Rock, Paper, Scissors fair in battle

Paper Armor Believe it or not, this was an actual thing; the Chinese used it for nearly a millennium as one of their main types of infantry armor. In addition to the obvious decreased cost factor, it ...
In Hoc Signo's user avatar
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108 votes

What could people notice about someone who is two times as dense as a regular person?

A number of common situations could give them away. If you ever paid attention to people getting in and out of your car, you notice that it shifts by noticeably different amount depending upon the ...
Gary Walker's user avatar
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100 votes
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How would someone destroy a dam in a world without explosives?

Forts using stone, rock and earth walls as fortifications (and in some cases, still standing !) were often attacked during sieges. Such a wall has much in common with a dam. To breach such a wall ...
StephenG - Help Ukraine's user avatar
89 votes

What difficulty would the Roman Empire have besieging a fantasy kingdom's 49 m wall?

Laying aside the 112,000 man army (which is monstrous), I'll address Rome and the wall. Rome was entirely capable of working through almost any typical engineering problem involving such a wall. The ...
JBiggs's user avatar
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82 votes

Suitable jobs in Ancient Rome for time travelers

Spice Trader First they pick up lots of spices at their local Mall-Wart. Then they carry them back in time to when they were fantastically valuable. Profit! Traders come from faraway countries and ...
Stig Hemmer's user avatar
67 votes

How would someone destroy a dam in a world without explosives?

A more devious scheme to bring a dam down: A secret second dam above the main target dam. You simply install a second dam above the main dam (as high as possible ideally). You reduce the flow ...
Thorsten S.'s user avatar
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67 votes

What non-electrical, basic tool from today, could be made that would change the world in ancient times?

In Europe, the stirrup. They were in use in China by the fifth century, but were unknown in Europe, and give a very significant advantage to cavalry as well as facilitating other uses for ridden ...
Mike Scott's user avatar
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66 votes

How to completely destroy a city, without leaving clues for humanity 4,000 years later?

Rock and clay don't burn well, leaving you with a lot of dressed stone lying around to say there was once a city here. Fire from above implies volcanoes, as we learned from Pompeii, that's actually a ...
Separatrix's user avatar
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64 votes

Could the Romans have colonised the New World?

The Romans, or rather the Greeks, because in Roman times the vast majority of mariners were Greek, and possibly Phoenician, could have crossed the Atlantic. Technically. The classical world had ...
AlexP's user avatar
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62 votes
Accepted

Suitable jobs in Ancient Rome for time travelers

The history of Ancient Rome is long, and to provide any kind of meaningful answer we need to fix a time-frame; consider that the history of the U.S.A. begins in 1776, less than two and a half ...
AlexP's user avatar
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60 votes

What modern technology would be most revolutionary to ancient Greeks?

I am far from the first to think of this, but alphabetical long distance signalling, whether by Semaphore line, heliograph or shuttered lantern gives you the biggest bang for your buck as an invention ...
Lostinfrance's user avatar
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59 votes

What non-electrical, basic tool from today, could be made that would change the world in ancient times?

Hygiene: A powerful battlefield weapon If you really want to get the attention of powerful people, teach them how to keep their soldiers alive when the enemy is dying. Through much of history, ...
Andrew Brēza's user avatar
58 votes

What difficulty would the Roman Empire have besieging a fantasy kingdom's 49 m wall?

The Romans would mine the wall The reason that the Romans had to scale the walls at Masada is because it was built on a rockface. Mining into a rockface is hard, though it could be done, slowly. Your ...
kingledion's user avatar
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57 votes

What could people notice about someone who is two times as dense as a regular person?

In addition to the answers listed, here are some more things that these people will need to be careful about, otherwise it could put them in a situation that could result in their exposure: Speaking ...
Anketam's user avatar
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53 votes

If the Romans found one working steam engine would they have been able to copy and use it?

What's a "steam engine"? A steam engine is an external combustion engine which uses steam as the working fluid. So we have: Newcomen's original atmospheric engine? The Romans (or rather the Greek ...
AlexP's user avatar
  • 89k
53 votes

How to completely destroy a city, without leaving clues for humanity 4,000 years later?

How about a catastrophic flood? Have the city built on a large river. A landslide further up blocks the river and causes an enormous lake to form (also cutting off water supply to the city causing ...
Tim B's user avatar
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51 votes

What could people notice about someone who is two times as dense as a regular person?

Besides what everyone has already said: their steps would be generally louder. They would impact the ground with twice the energy on each step, for the same footfall used by a person of regular ...
The Square-Cube Law's user avatar
50 votes

How to stop a massive canal system from silting up?

Dredging The first thing to note when you search for dredging is that it's not Wikipedia at the top, it's an advert for a dredging contractor. This isn't something that can be ignored, it's a matter ...
Separatrix's user avatar
  • 118k
46 votes
Accepted

How to completely destroy a city, without leaving clues for humanity 4,000 years later?

I have much academic experience with some of this, especially the second part of your question. I'll address a few different sides of things. The most drastic way I can think of that could ...
Dan's user avatar
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46 votes
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How can I prevent an oracle who can see into the past from knowing everything that has happened?

If the collective mind contains memories of people, well... It contains what people remember, not the factual truth. This poses multiple problems: Conflicting memories, which may either be mutually ...
The Square-Cube Law's user avatar
46 votes

What non-electrical, basic tool from today, could be made that would change the world in ancient times?

Since this question has the reality check tag, I'm going to have to point out that people in ancient times weren't stupid. They just lacked the means and the knowledge base. They were far more in tune ...
DKNguyen's user avatar
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44 votes
Accepted

How would the punishment of murder change if people could just respawn?

It would be treated as equivalent to assault, if the person respawned. After all, assault is defined as causing someone pain or injury without killing them, so it seems pretty much equivalent. If they ...
Ettina Kitten's user avatar
41 votes

What tool would a Roman-age civilization have for the breaking of silver and other metals into dust?

Roman age? I can give you a stone age method: Grind it between two rocks. Silver has a mohs hardness of 2.5. Granite has a mohs hardness of 6-7. So you can use a rough granite stone to grind silver ...
Philipp's user avatar
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40 votes
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Is it possible for an ancient contraption to survive modern-day attempts of breaking in?

Water. The misadventures on Oak Island illustrate this well. Supposedly the treasure of the Templars is there. But no-one has been able to get it. It has not been for lack of trying. https://en....
Willk's user avatar
  • 305k
38 votes

What modern technology would be most revolutionary to ancient Greeks?

Simple military technology would make the biggest impact, some ideas. The longbow, along with conscript soldiers using the massed volley firing technique would outrange generally existing bows, but ...
Josh King's user avatar
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38 votes
Accepted

What would the Ancient Greeks call a wizard that can control life?

Latin is not derived from Greek. That apart, you are probably looking for something related to Moirai They controlled the mother thread of life of every mortal from birth to death. They were ...
L.Dutch's user avatar
  • 287k
37 votes

How could an ancient race warn the future in a universally understandable way?

Where have I heard this before ? Sounds something like the plot of practically all the Indiana Jones movies, not to mention The Fifth Element and, well, lots more. I doubt this is possible. Using ...
StephenG - Help Ukraine's user avatar

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