New answers tagged physics
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If you want to direct lightening and you don't want to use technology then how about using something like fine damp sticky but very strong spiders silk strands? Spray it on the enemy and then blow the other end up into the air to be caught on the breeze. Whilst the target is trying to disentangle itself from the sticky strands the other end will be floating ...
2
It looks like somebody did the math for you.
The energy per unit mass in a bit of the spring that is strained with
a strain of $ε$ is $0.5 \cdot Y \cdot ( ε^2 ) / ρ$ where Y is the
Young's modulus, and ρ is the density.
The stress τ is (roughly) related to the strain by $τ = Y \cdot ε$
and the maximum stress you can cope with [in a spring that ...
3
For plausible real-world materials such as a spring made from single-walled carbon nanotubes, you'll get specific energies of the order of 2.125MJ/kg (3.4MJ/l). That's pretty good... much better than lithium ion batteries, but its a long way short of chemical energy storage.
You could handwave your springs being much stronger, but be aware that this would ...
2
Need 2 steps
1) let the star or some other process "blow away" all atmospheric gases (the complete atmosphere and all vapor from step 2 ... are completely removed - takes care of lifeforms in the atmosphere and most life on the surface
2) heat up the whole planet to make it a giant "drop" of lava again - this takes care of remaining microbes on the ...
3
To get underground enough on your average planet, so as to exterminate all forms of life, you need:
excavators. Very powerful machines; they've found Archaea three kilometers underground (a very long time ago, those areas were probably near the surface).
sifting and hunting robots to examine the soil.
some way of insulating the already disinfected area from ...
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Drop a large asteroid into the planet.
This should effectively turn the entire planet back into a molten mass of stone which will kill of all and any life on the planet from deep underground, under water, in the air and anything on the surface.
All your water will evaporate away, but it should still stay within the atmosphere of the planet, so once the ...
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I wouldn't write off gamma ray bombs and beam killer weapons due to hard science. You do realize that in hard science, any starship with engines powerful enough to travel between the stars can just use those engines to irradiate the planet. There is no such thing as an unarmed interstellar starship in hard science. I would be more worried about not ...
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In that environment, life would evolve in the air.
The devil is in the details. You ask about a world with physics "nearly the same as ours," but such a world has such extraordinarily different physics than ours that we can't even remotely begin to apply the word "nearly." Applying "physics" would be difficult enough on its own. I would consider a world ...
answered Dec 10 at 23:59
Cort Ammon - Reinstate Monica
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if anyone is wondering, the number for a full sized full one is 6739599814.88, i'm assuming newtons of force? the 6 billion 7 hundred and 39 million 5 hundred and 99 thousands, 8 hundred and 14 point 88 newtons* of force is pulling down about several hundred times considering the amount of the full sized and little sized towers.
thank @nzaman for providing ...
4
In addition to the answers already posted, what about messing with your brain?
From my limited understanding of biology I believe neurons operate via electrical signals so depending on how precise your control is and how well you understand the neural structure of the brain you could in theory manipulate thoughts by initiating tiny changes in the electrical ...
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Coincidentally I just watched a Scott Manley video on this topic published in May 2018.
A small asteroid called 2015 BZ509, and a large gas giant named Jupiter have a resonance in their orbits which is self-correcting. Every time they approach, if the smaller body is too fast or too slow (that is, early or late) the influence of the larger body applies a ...
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I find it somewhat helpful to think of the Weak Force analogously to the Electromagnetic Force (there's a reason they were the easiest to unify, after all). Neutron decay can be modeled as a free neutron emiting a W- boson, which immediately turns into an electron / antineutrino pair. Compare to a charged particle emitting a photon, which, given high enough ...
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The most interesting possibility here is nuclear alchemy. If the practitioner can have very fine grained control over the weak force on bulk materials, the possibility exists that they could trigger specific modes of radioactive decay in specific elements, causing them to become other, possibly more useful, (and perhaps even stable) elements. "Impossible" ...
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Assuming your planet has a similar equatorial bulge to Earth, yes.
If you don't mind your "polar" ring being a few degrees off exactly 90% inclination from the planet's equator, anyway (and this will vary slightly depending on the planet's axial tilt and the inclination of any major moon or moons).
Put the ring in a sun-synchronous orbit. For Earth, this ...
0
you have a more fundamental problem, but fixing it will fix a lot.
continental plates are normally not surrounded by attached oceanic plate on all sides. Usually just some of the sides, look at the this map and you will notice almost no continent is completely surrounded by attached crust there is a a plate boundary on at least one large stretch of coast, ...
0
I see some issues in your arrangement.
When a tectonic plaque descend below another, it will cause the one above it to fold and corrugate, generating mountains. This is clearly visible in the mountain regions surrounding the Pacific Ring of fire
As you can see the areas where the plaque sinks, marked by trenches, is close to region with mountains and ...
answered Dec 5 at 13:32
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NASA recently discovered a very interesting resonant pair in two moons of Neptune, Naiad and Thalassa. Their orbits (nearly <2000km) intersect and have periods of 7 and 7.5hrs respectively. Even though they are quite close at nearest pass (<4000km) they never actually collide because of this ”unprecedented” 69:73 resonance.
This resonance was ...
32
You should have a look at Janus and Epimetheus. They are two moons of Saturn that exchange orbits approximately every four Earth years. This setup is probably not stable for more than a few billion years but it might do for what you want.
Epimetheus orbits closer to Saturn, so has a shorter orbital period
and eventually approached Janus from behind.
...
2
Oh, maybe that is what the magic is about.
Under normal circumstances, you can't have perfect synchronous orbits. Suppose the orbits are, to pick numbers, 1000 hours and 10,000 hours. That's about 40 days and about 400 days.
So whatever is supposed to happen at the first coincidence might be off by some tiny amount. This tiny discrepancy grows for 400 ...
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Ok, so you say 'Harmonic Orbits', but actual Space-Talking-Dudes call that 'orbital resonance', and it's the solution to your problem.
We've got an example of something ALMOST exactly like what you're talking about right here in our own solar system with Pluto and Neptune. As puppetsock rightly points out, their orbits don't actually intersect because of ...
2
How do things work?
They work very, very simply: it is the world where you live in now.
Any weapon that we have is based on one or more of the 4 fundamental forces or its usage.
What you call spell is just the sequence of steps one need to execute to produce and fire the weapon. Some are more long, complex and powerful (aka thermonuclear bombs), some ...
answered Dec 4 at 7:48
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There's a bunch of questions that commenters have already raised but I'm going to give it my best shot. I'm assuming that the metal object is like the 'sun' for this planet, so this planet orbits it. No idea if this is feasible, but I'm going to assume it is (i.e this metal thing has enough mass to attract this planet of yours).
First of all: planets don't ...
1
Precipitation.
The big advantage here is that it starts off at an (almost) arbitrary altitude, so all you need to do is open the roof of your 10-mile-radius tank and collect away.
Sure, it'll take a while to fill up your high tank. But when you're operating on the time scales of Stonehenge, waiting a couple thousand years isn't a problem.
3
Construction / demolition debris.
From comments:
There are many types of materials where people will pay you to take
it off of their hands. – Michael Kutz 13 hours ago
Debris and especially demolition debris must be hauled away from the site where it is generated. People are paid to haul it away, rendering the cost of such materials a negative ...
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The box would need to be a box within a box, with a vacuum in the gap but with a couple of layers of photonic crystals.
Heat transfers through materials via three methods:
Conduction (vibration of atoms)
Convection (energy transfer through gas)
Radiation (infrared light emitted by the hot material)
A vacuum would sufficiently deal with Conduction and ...
1
Silica based aerogel
Withstands temperatures of 1200 C and has very low thermal transmission.
Aerogel would not be durable enough on its own, so you would want to make an inner box of tungsten insulated with a layer of silica aerogel and an outer metal layer for durability. Something like stainless steel or titanium would work well.
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Construct a cooler out of LI-900 tiles. The tiles used on the Space Shuttle for re entry.
They can withstand high heat, 1500 C and transmit very little heat through the tile.
LI-900
3
You will need a high-temperature thermos.
@Surprised Dog gave an idea of making the inner part of it of tungsten. This may be good, but may be an overkill - the lava that we see erupting is never even hot enough to melt iron (melting point 1538 °C).
To prevent heat loss, the inner part of the vessel has no air, and reflective coating prevents radiating ...
-1
The hardest problem with containing lava is finding a container that won't melt on contact. Tungsten is the metal with highest melting point of any element at 3422 degrees C. In fact, Tungsten has such a high melting point that if you throw liquid tungsten into lava, it will freeze.
So you will want to make your container out of that. Tungsten is not an ...
7
If I had to guess, it would straight up be water. Some big companies literally pump millions of tons of this stuff out of the ground and then distribute it across the globe to make a very healthy profit.
I found this article which states that "Coca-Cola Amatil" pays 2.40 for a million litres of water. Basically it costs $2.40 for 1000 metric tons of water, ...
1
Fill dirt can be had for as little as 3-12 dollars per ton.
For comparison, Sand costs 5-15 dollars per ton. When looking at these materials, the dominating factor is going to be transportation costs, not raw material cost.
3
As others have observed, almost everything involved in the regular day-to-day interaction with matter involves the electromagnetic force.
The problem is though that many of these interactions are at a very small scale. Materials can't interpenetrate each other in a large part thanks to the Coulomb forces causing the electron clouds around their respective ...
5
Almost everything people experience on a daily basis is electromagnetism. Full-blown control over this force is almost indistinguishable from reality-warping. One could plausibly even pull off some weird transmutations of elements, by reducing the charge between protons to get cold fusion.
It's more helpful to narrow things down to specific aspects of the ...
4
This person, since their powers can affect electromagnetism, would be able to induce variable magnetic and/or electric fields.
Thus it would be possible for them to:
emit light
induce electrostatic charges
move charges
induce magnetic fields, thus attracting iron
deflect moving ions
[...]
As a side note, every time we interact with the outside world we do ...
answered Nov 29 at 21:12
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When gravitational waves reach Earth, they usually give a strain of $\delta L \over L$$=10^{-21}$.
If we assume that they scale with the distance the same way electromagnetic waves do, thus following the inverse square law, we can get an estimate of the distance needed.
LIGO detected the first merger of black holes at 1.3 billion light years away.
If we ...
answered Nov 28 at 12:27
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I think I can now answer my own question, having come across some decent references I hadn't found before asking it. I found the equation for the gravitational strain $h$ - the proportional change in length of an object due to gravitational waves from a mass $M$:
$$h \approx {{GM} \over c^2} \times {1 \over r} \times {v^2 \over c^2}$$
(Source of formula)
...
1
We know of no way to do this.
As to your particular nano-scale contraption, that one is actually a rather interesting little story. We've actually investigated the idea of capturing energy out of Brownian motion with nano-scale devices. The structure that we relied on was a water-wheel of sorts with a ratchet. The idea was that random collisions in one ...
answered Nov 27 at 17:14
Cort Ammon - Reinstate Monica
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0
Sure, we can do it today. As long as you are taking heat from a hot place to a cooler place, there's no problem with the second law of thermodynamics.
You can use a solar updraught tower. Works best where there's a lot of solar thermal energy. Take a bit of desert, or a nice big black tarmac area, build a tower to collect the rising hot air and funnel it up ...
2
As it happens I've been putting a lot of thought and reading into this exact problem lately, and it's a real head scratcher. This problem comes up a lot when people talk about spacecraft design and waste heat issues. Intuitively it seems like obviously you should be able to capture heat and turn it into useful power.
The problem is Entropy. Here's a ...
4
We can already do that, and no, it does not violate the laws of thermodynamics at all. This is called the Thermoelectric effect. As for doing this effectively at scale, it's generally more expensive than other means of heating, cooling, and electrical generation, so it's not done very much. There is research about it, such as this.
Currently it's ...
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This idea is violating the laws of thermodynamics.
Simply put, forget about it.
Thermodynamics laws are the best enforced laws in universe. There is no way around them.
Those laws clearly state that you cannot convert heat to usable energy, you can only convert a fraction L of energy from a temperature T1 to usable energy if you can discard some energy at ...
answered Nov 27 at 14:16
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Apparently, Rocky Marciano (the model for Rocky Balboa) had a punch measured at approximately 1000ft-lbs, or 1355 joules in less weird units. He weighed a mere 85kg, so he's a bit lighter than your target 100kg, but it seems close enough.
Lets assume that all else being equal, the energy of a punch scales linearly with the weight of the puncher. A 100kg ...
2
Assuming the punch does not penetrate, then the effect in terms of momentum transfer would be the same as someone firing a .50 cal rifle, like a Barrett Fifty.
In other words, very little.
Bean bag rounds which the police fire from 12-gauge shotguns, hit with around 100 joules of energy, kinetic rounds like plastic/rubber bullets, 40mm sponge grenades, etc....
1
20 m/s is a speed of a target (if it will not fall apart) after a punch. This would definitly rise what left of him into the air for about 0.5-1 second (depends on punch vertical angle) and flight distance 10-20 meters
Asuming armor would prolong the acceleration time - it would give about 200-100g of acceleration. Crush dummies bearly survive this (...
2
The human arm is 6.5% of total mass therefore 6.5 kg. So your 20 kJ punching-arm is travelling at 78 m/s. Assuming an inelastic collision and a 5kg chest plate, the combined mass of (puncher's arm plus victim plus chest plate) is now moving at 18.9 m/s (42 miles per hour). That's equivalent to being hit by a car and would knock you back some distance. The UK ...
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You are effectively spreading the energy of a .50 caliber bullet over the area of a human fist, so let's do some math. The diameter of a .50 caliber bullet is (unsurprisingly) half an inch, giving it a frontal area of 1.27 square cm (we're disregarding the fact that the bullet isn't just a cylinder, but it'll do for a first approximation).
Now onto the ...
answered Nov 27 at 3:48
Gryphon - Reinstate Monica
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2
Magnetic Fields
Water is diamagnetic, meaning that its magnetic polarisation aligns itself opposite to an applied magnetic field (thus, water is repelled by magnetic fields). This has been demonstrated in "levitating frog" experiments. If you were able to somehow get a (monodirectional) magnetic field to protrude out of the ocean, you could hypothetically ...
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This is a major undertaking. You will need a civilization somewhere between 1 and 2 on the Kardeshev Scale, and you will need to do it manually. If you have a Dyson sphere you should be able to muster up enough energy to pull it off.
Start by boiling the oceans. Raising the global temperature to over 100C should do the trick. Alternatively, microwaving ...
0
Levitation actually doesn't need to consume any energy. A well-constructed levitation spell simply suspends the conversion of gravitational potential energy into kinetic energy. This costs just about nothing. You would only need to spend energy to ascend, and you would recover energy from descending.
The inefficient way to do levitation is to produce a ...
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