# Tag Info

4

Apart from the other answers pointing out this is fairly possible with modern/future technology, I would like to point out another reason this is impractical and will probably not be developed further: Balance Iron man seems to hold his own when boosted from the bottom, balancing himself with boosters on his hands. But in reality balancing on boosters from ...

2

This is one of those ideas that is cool but extremely impractical at best, as you'll see in this thread on Portal's boots for some other ideas for achieving the same effect. The short version there is that it might be possible to find something, but it would be extremely hard to be effective in any kind of reasonably sized package. While you're talking ...

16

Sure. They have jet packs. https://www.youtube.com/watch?v=EAJM5L9hhBs Jet packs have been a sci fi staple since Flash Gordon. The land assist suits they have in Call of Duty are lifted straight from Heinlein's Starship Troopers, 1958. I pictured the jump units in Starship Troopers as big, but the marines were wearing full exosuits and so were not ...

2

How would their flight change as they enter the central zero gravity axis area? Once they're accustomed to it, I expect they'd flap their wings less often, since they don't need the lift to stay in the air. Would they have trouble in this area and avoid it? Assuming there is air up there, I expect they'd be fine. Most likely "flight" in the region (...

1

The key problem is the amount of acceleration that your passenger can tolerate. You need to leave the atmosphere at as speed of at least 12.5km/s to be able to pass through the moon's L1 and enter its sphere of influence. Lets say, your passenger can tolerate a 20g acceleration (approx. 200m/s^2). With this top acceleration, you need to sustain that ...

4

The atmosphere of the Earth tends to destroy fast-moving objects. This is related to Newton's depth approximation, where we find that a projectile tends to penetrate through approximately its own mass of material before it stops. Newton fired cannonballs into sand, and found that they penetrated approximately as far as the column of sand that weighed the ...

0

No You may be confusing two different tropes, namely filling the lungs with a fluid to help equialize the body while under constant environmental pressures (such as deep sea) vs G-forces. G-forces impact the human body greatly based on the direction of the force. In some directions, it causes blood to pool in the lower extremities, keeping blood away from ...

1

Yes, a mechanical device called a Slingatron was proposed for space launches. I wrote about it some years back; the developer (Derek Tidman) felt that there was a huge bias in the establishment against this approach and he never made much progress with it. However, a starup called SpinLaunch are now going with the same idea, so we may yet get to see if it ...

1

It's technically possible, but there are a few difficulties with just shooting yourself straight there. So, as a baseline, you need about 15,000 m/s (meters per second) of ΔV for a traditional rocket to reach the Lunar surface. That number comes from the below slide from a 2012 presentation by NASA. I believe this includes deceleration burns and ...

0

It can be some kind of electromagnetic launcher if it has to. You are looking for a Space Fountain elevated Rail Gun. Space Fountains technically are a 'rocket', just of another format. Rather than relying on combustion of fuel in a rocket engine to propel hot gas out the back, you instead rely on throwing around material that can interact with an ...

-2

I think you should definitely consider a trebuchet over a catapult. They are far more superior siege engine, and able to launch a 90kg projectile up to 300m distance. The moon being at 384 400 000 meters from the earth, you just need 1281333.34 time the power of a traditional medieval trebuchet. I would recommend: build 1281334 trebuchet and connect them ...

0

To work out the heating from air resistance, think of the column of air above you and imagine being hit by it at orbital speed. Pressure at sea level is about 100kPa, so there's about 10,000kg of air above every square meter. Orbit speed is 11km/s, so there's 600GJ of kinetic energy to absorb. The heat capacity of steel is about 600J/kg k, so a million kg ...

5

Linear accelerator launchers (based on a combination of maglev and linear induction motors, usually) go back to the 1950s in fiction (Heinlein's Starman Jones from 1953, and The Moon is a Harsh Mistress from 1966). There are significant limitations in using these from within an atmosphere, but there are ways around them (route the rail up a very high ...

-2

From the other answers, any sort of gun/catapult seems to need such an enormous initial speed (muzzle velocity?) that it would be impractical. I have no idea of the physics, but if you were able to use (say) the sides of Mount Everest as the base of your "gun", maybe you would have a slight height advantage and a lower density of air to get through. I'd ...

2

There are a whole bunch of different ways to determine the thickness of a planet's ice sheets; over the decade, dozens have been tried on Europa and other icy bodies. Broadly speaking, as we're working from a purely theoretical perspective, our method will have to be thermodynamic in nature - we can't look at cratering patterns or rifts in the ice. I'm going ...

28

To get to the moon you need to reach a speed of at least 7 mi/sec. What about giant catapults? A catapult will never reach anywhere near that kind of speed. It does not matter how long you make the arm, no man-made materials can survive anywhere near the sort of torsion that this would require. What about railguns? The world's strongest military ...

10

I'm going to ignore that your subject talks about a "person", because the body of your question basically says to do that. It sounds like you want a space gun. The article has some information on plausibility, but the short version is that, if you want to reach the moon, or even just a stable orbit, you have issues with both the acceleration needed (but we'...

0

You cannot do this unless you allow for some finite range of EM-radiation blocking. Check out Planck's Law and Blackbody radiation formulas. In short, unless you drop an object to absolute zero temperature, it's going to radiate. You can't stop this from happening. I strongly doubt that current understanding of QED and gravity waves allow this sort of ...

1

A lot of questions in there, but I think overall it can work. First, gravity waves and conservation of energy. When gravity waves act on the world the do so as a transference to kinetic energy (some debate on this in physics, of course). If that is the case, then EM waves transforming into kinetic energy transforming into gravity waves should keep ...

0

This could work easily enough if all the EM radiation is not muffled but simply ends up somewhere else. Any light entering the area, or emitted within it, is not visible because it's not there. Electric currents would still flow, chemistry would still function and atoms and molecules would not fall apart. It might be a little chilly, but reality should not ...

1

While the question as asked does not seem to have a reasonable answer, I would suggest that (assuming firearms are not allowed) torsion based weapons might be considered rather than tension weapons like bows. Ancient ballista were designed to transfer the draw energy into skeins of rope or sinew, which could then store the energy for a short time while the ...

2

In most quantum field theories1, we have a quantity called the Lagrangian, from which we can derive information about the behavior of our system. It consists of a number of terms representing different quantum fields. Now, we are mathematically forbidden from naïvely adding mass terms by something called a gauge symmetry. However, it turns out that we can ...

1

You don't need a superior bow and arrow. You need superior archers. If you replace the limbs of your commandos with powerful, enhanced prosthetics and enhance their torso with more resistant materials and synthetic muscles, you can end up with archers that put way more power into each shot, using bows with far higher draw strength and heavier arrows. ...

5

The filling the lungs in an incompressible fluid will increase the the g forces a pilot could handle since g-forces would be uniformly distributed evenly across the body, in side and out. The pilot might need hydraulic assistance with respirating. The thinker medium might be too much load for the diaphragm and ribs to move in and out of the lungs. But, a ...

5

This would be a very bad idea if the liquid is like water. Alright, we need to explain a few things here about the difference between straight line acceleration and the kind of agile moves you describe in this question, and how a medium like water reacts in each case. To start with though, we have to explain something else; for all intents and purposes, ...

1

Let me see if I got this right. You want to conjure an object, have it contain enough mass and gravity to collapse on itself without dissipating, motivate it to move at FTL speed, drag your vessel along with it, then create an new repelling object, motivate that object to follow you at equal speeds, close enough to push you towards the dragging object, all ...

5

The trick here is "generates". Let us consider just one hole, to keep it simple. The ship generates a black hole in front of it and falls towards that hole. There does not seem much prospect of bolting some sort of rig onto a real, wild black hole to hang it in front of you, like a carrot hung in front of a donkey. The event horizon and all. But your ...

9

Not going to work. You can’t lift yourself off the ground by pulling your own pants higher. The black hole pull runs into the same problem. Gravity pulls two things together... it doesn’t chain them along. The white hole would just push you into the black hole faster because you’re closer to the white hole than the black hole is. Gravity cannot accelerate ...

4

The first issue I see up front is how do you keep the black and white holes suspended "a set distance" from the front and back of the ship? You'll need some force to accelerate the holes, which doesn't seem to come from anywhere, since you're using the holes to accelerate the ship in the first place. This would be like bolting a rig to the top of your car ...

2

I would like to address several problems in your question. If flat spacetime had a Kronecker delta metric instead of the usual Minkowski metric then the "invariant" spacetime interval wouldn't be invariant ( if you are still thinking of $t$ as time, otherwise it's an invariant space distance). Also while defining a spherically symmetric metric in spacetime ...

1

You mention the Dresden files, and that alone gives you some important take aways. Dresden can call fire, but in one of the books he does explain that once he calls it, it still has to do business with the laws of physics. You can set something on fire, but once you do, thermodynamics takes over and entropy reigns supreme. Likewise with cold. Freeze ...

0

All of a sudden, Michael was on fire. For a second he could resist the sensation, but the knowledge that none of it was real was quickly being snuffed out by every nerve ending in his body screaming about stopping, dropping and rolling. He crumpled to the ground, hacking and coughing, as his lungs and brachia sent frantic messages of an unusable gas mixture....

2

I'll put this here to summarize things: The explanation of particle vibrations is as good as any from an in-universe attempt to explain things. However, you should think hard about how such an ability expresses itself so as to avoid issues in regards to what the characters can do, due to the vast amount of things one could do with such an ability as-is ...

5

In the tabletop RPG system G.U.R.P.S., pyrokinesis is included as a subset of telekinesis. According to the author, Steve Jackson (yes, the guy from the Munchkin game), this is using telekinectic power to make molecules vibrate faster instead of moving them from one place to another. Do that in reverse and you have cryokinesis. A similar form of cryokinesis ...

6

Since you are talking magic, you can impose limits however you wish. I'll tell you what I would do though. First limitation is to consider Magic to be energy. Seems like you are doing this already. It gives you a limit based in understood physics. You can neither create or destroy energy just like you can neither create or destroy Matter. You can ...

3

The frequency of sound from flapping wings depends on their size. Think of the flapping of a pigeon versus the buzz of a bee and the even higher whine of the mosquito. Make your drones small enough, and the sound will be too high-pitched for human ears. Or, if you want a wild-science twist, arrange them so the sound waves from each drone are cancelled out ...

2

With nano materials you should be good. Millimeter-sized drones would hover maintaining centimeter-sized gaps. When it's time to assemble, they would deploy "tentacles" which should connect to each other, forming a strong lattice. Nano materials can, in theory, provide sufficient strength and rigidity for this lattice. This lattice, though, would be just a ...

4

Electrostatic propulsion drone. https://www.theguardian.com/science/2018/nov/21/first-ever-plane-with-no-moving-parts-takes-flight The first ever “solid state” plane, with no moving parts in its propulsion system, has successfully flown for a distance of 60 metres, proving that heavier-than-air flight is possible without jets or propellers. The ...

4

Your little drones are 2 rotors, spinning in opposite directions. The net spin of the two rotors cancels out. The rotors are not flush against each other and can tilt slightly allowing directional control. Lift is controlled by the angle of the blades within each rotor. The spin is very fast, very quiet and constant. They never stop spinning.

2

Problems & Solutions Safely entering the area The extreme sudden difference from a sharp change would likely damage most hints to enter the field. Because of this, you should likely use one of the following methods. The field has a gradient barrier, or objects that enter partially get a similar field around their body as they enter. These allow for less ...

1

How about the very real Gigantopithecus blacki? This Ape could indeed climb if it desired to. Presuming suitable hand holds of course. Even assuming a larger Ape, Ape's are evolved from climbing creatures. The only reason why they do not climb more, is that most tree branches are not strong enough to carry their weight. In terms of trees, the upper-bound ...

5

I had an idea for a swarm of tiny drones... that could form into shapes and structures, even mimic the shapes of living creatures. This is a macroscopic version of Utility Fog, a concept that involves a co-operative swarm of nanomechanical devices that use telescopic grasping limbs to interact with each other and their environment to form shapes of varying ...

3

You can base the behaviour in the fire ants, they grab eachother to form different ad hoc structures, to float, seal holes, form bridges and much more. Since yours are purposely designed robots, they can be slightly better and/or stronger, creating larger structures. Sources: https://www.youtube.com/watch?v=NpiDADw5Omw https://en.wikipedia.org/wiki/Fire_ant

4

Rather than copying the list of resources to here, I suggest that interested parties browse the answer to this previous question (A list of worldbuilding-resources?) where an humongous long list of resources is to be found. You could do worse than start with this intro youtube vid to the solar system's geology. Here's another touching on some big moons of ...

Top 50 recent answers are included