137

Perpetum mobile Other answers aside, you could for example modify a hydroelectric power plant by placing an "input" portal below the turbines and an "output" portal above. Hey, infinite energy!


135

In eggs As in, a fertile dinosaur egg, not the adult. Moving livestock is always tricky, even more so when said livestock is composed of strong and dangerous creatures, which have a tendency to die easily in the wrong temperature, thanks to the fact that they're cold-blooded. If pirates wanted to smuggle these creatures from their distant territories back ...


120

Status symbol. Plain and simple. Doing a carbon copy is easy and cheap. But if you can afford the original one it means you have a huge load of moneys at your disposal. And those moneys are no good hidden in some bank account. Impress your guests with what they can buy. P.S. In a less sci-fi scenario, there are people on Earth who like to have golden ...


117

A similar concept has been mentioned in other answers, but one way to make a train like this viable would be to have pods at stations that "dock" with the main train rather than many trains running at different speeds. There would be a period of acceleration followed by the pod locking on firmly. Here's an example where a pod docks to the top of a train at ...


103

Some uses that came to my mind: Use it as garbage disposal. Just push it to an offline portal. Especially useful for radioactive nuclear waste for example. Use it as a time travel device to the future. Let's say you want to travel 100 years to the future, then just calculate how slow you would need to move into the portal so you end up at the other side 100 ...


96

As far as a reality-check goes, wolf-mounts are probably not happening. A fair few people have discussed physical size, diet and dangerousness being barriers to wolves being a successful mount, but there are key differences in the skeletal structure of predators (big cats especially, but wolves too) that make them unsuitable for riding. It all comes down ...


95

I'm looking for plausible reasons or obstacles that would help explain why traditional jet/rocket/prop-based air travel is not practical Killer pigeons. Well, not exactly your ordinary columba livia domestica, but pigeon-analogues nonetheless. They live almost everywhere, breed like crazy, and luckily, unlike their Earth cousins, dislike the noise and ...


84

While hopping on one moving train seems reasonable for a healthy young adult, hopping two hundred seems a little excessive and dangerous... Also I would imagine that most people going on a long distance trip will be bringing luggage. I'm sure I could jog up and on to a slow moving train unhindered, but a little less sure about doing so with a suitcase in ...


78

Horses They are smart enough to not crash themselves on others, even if their riders are completely drunk.


75

You have solved food preservation Who needs a clunky old refrigerator that only slows the rotting and decay of fresh food? Just make it so your food doesn't experience time! Meet the new tele-preserver, which has the input and output portals side-by-side, and which constantly cycles the food into the portal unless the door is open. Your food is still ...


75

Entertainment There are days when absolutely nothing will make you happy other than the sound of a Harley Davidson motorcycle polluting the atmosphere in style. To Impress People One of my favorite scenes from the book The Stars My Destination is when the protagonist, hiding in plain sight via enormous wealth (and in a world with mental ...


72

The short answer is trade. The larger answer is that the act of trading develops and requires a range of secondary and tertiary activities which are themselves economically significant. Consider, the trader needs a place to exchange money, bed down for the night, feed his caravan and all the men who ride with him (or the ships crew if a port). Cargos need ...


66

Some helicopters are able to transport ground vehicles. Check out the weird Sikorsky CH-54 Tarhe: And this is how it is used: You may also be interested in the Boeing CH-47D Chinook: Or maybe try the Mil Mi 10: If flying isn't your thing (it happens), you may use a Zubr-class LCAC, which is an obscenely huge hovercraft:


66

Congratulations! You just made container ships obsolete! Container ship is the tool of transport when talking about bulk transport: Even if you ship goods at relatively slow speed of railway transport, you: Actually made shipping goods faster, because you save time on unloading and re-loading cargo from and to ship Made ton of savings on fuel, because if ...


65

You can't control your direction in a sailboat when there is just one current. Sailboats are only able to move into a different direction than the wind is blowing because they have a "second sail" under water, called a keel. The actual physics on a sailboat are a complex topic. But the bottom line is: When the aerodynamic force on the sail and the ...


64

Make your portals (to borrow a term from physics) 'magnetic'. In other words, two magic portals that are too close to each other in space will attract each other and merge into a single portal, and because portals between planets require tremendous amounts of magical energy, they have tremendous 'magnetic' attraction. Two portals that have their origins and ...


60

This is the basis for the real world economic theory of Comparative Advantage. The aliens can produce any of a large number of products with their industrial capacity. Similarly, Earth can use its capacity to produce any of a large number of products. Let's assume that the aliens can produce anything more cheaply than humans. The theory of Comparative ...


58

Rockets Rockets are the fastest means of acceleration we have but it's just not efficient but for a stargate, this isn't a problem as you can open the gate to refuel. You effectively build the stargate into a ship and use the gate to refuel and resupply. Crew can come and go as wanted. As tech improves, you bring it through the gate and upgrade the ship ...


54

A canal with a gradient and a flow is a river. And navigatable rivers are pretty much flat. Taking a nearby river (the Medway) and measuring the change in height from the coast to the point at which it becomes essentially unnavigatable gives an average gradient of 0.0003 or about 30cm per kilometer. Wider rivers have lower gradients. The Mississippi has a ...


53

While the scenario painted may seem quite bizarre and downright deadly, the fact of the matter is, minimal traffic regulation does not necessarily mean you need to drive an Challenger 2 Tank just to make it home from your downtown office park every day! As a matter of fact, we in the Traffic Tabulation Bureau have conducted a comprehensively exhaustive ...


53

As far as you want. Humans have trouble conceptualising large numbers. We can’t count them, so above a certain point we see the number ‘178654’ and our brains turn it into ‘many’. Doesn’t change the value of the number, just how we intuit about it. For anything bigger than the number we can imagine (varies from person to person) we start doing maths rather ...


52

Frankly, I would not bother with cars or trucks. Use a train! Any large diesel engine, or several combined, with a snow plow up front. As a bonus, you can add waggons for any goods you may want to carry (such as extreme amounts of ammunition and fuel for your flamethrowers), and most of all you can navigate without a problem: you know in advance where ...


52

You are kind of answering your own question. Human labor is the only possibility you did not exclude by your world setting. Historically we have been using either machines, animals or manual labor to accomplish tasks like these. Since it's medieval times machinery is off the table. Animals are off the table too, because of your world design. So there is ...


51

from wikipedia: "About 71% of Earth's surface is covered with water, mostly by oceans." So take away a couple of continents, and you have 85%. If only Europe existed, that would mean roughly 98% of the Earth covered in Oceans and there would still be trains in it. ETA to address comments: trains in a world mostly covered with water would have the same ...


49

The Fast and the Furiously Crazy Since you've eliminated the sensible solution (bypasses or double tracks), let's go with an insane one! All your trains have rail tracks running on top of them and extra wagons with ramps at the front and back. When a priority train approaches, they lower the ramps onto the rails and the priority train drives straight over ...


45

It has to be a motorbike... Having just been to the Philippines (and I imagine many southeast Asian and over populated areas are also like this), Motor bikes are everywhere and small enough to slip between cars, yet large enough that a car won't hit you because your going to damage it. In particular, I would recommend a Dirt Bike because it has the ...


44

Unpredictable weather with lots of microbursts, wind shear, tornados, and other unfavorable winds. Wind shear is one of the most dangerous things for an aircraft. Thankfully they are generally rare, on Earth. If flying isn't a question of if there will be a wind shear, but how many there will be, flying wouldn't be something that you'd want to do. Very ...


44

Depending just how fast one can enter the portal you have just made every other form of transport obsolete for speed of transit. If one were to set up two portals in vacuum chambers and run a sealed bullet train between them then you could go from say London to New York at a thousand odd kilometers an hour ground speed, that's faster than Concord ever went, ...


43

I decided to try to extrapolate from some known data. I used various sources to find that: The Harpy Eagle at 6 to 9 kg can lift a Three-Toed Sloth of 3.5 to 4.5 kg A Peregrine Falcon of 0.3 to 1.0 kg can lift a feral Pigeon of 0.25 to 0.4 kg An adult Human is typically somewhere around 60 to 100 kg The largest (known) bird ever was Argetavis magnificens, ...


43

While an interesting thought, I can see a few major flaws with this system: You are never the only one to arrive at an intersection. You will almost always be behind someone. They might not have the same financial status or preferences, and might opt to wait instead. This means you might have to pay not only your share, but also their share to get a green ...


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