New answers tagged physics
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Gravitational waves
Presumably, there would be gravitational waves emitted as the two compact objects slowly came close to merging. Given their small cross-sections, a direct, head-on collision is highly unlikely. A more plausible scenario involves an interaction with a third massive body.$^{\dagger}$ The white dwarf and neutron star would be inserted into ...
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Unfortunately, no.
Referencing the comments made by both @AlexP and @DWKraus and noting that one of the articles you cite states, "The detailed mechanism of the cicada's song is far from fully understood...." In other words, my answer is a best-guess.
A human-sized cicada would produce sound with a substantially lower frequency. Your largest cicada species ...
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The power level of the echolocation signal in bats is similar to that of the sounds the human voice can produce (order of 100 decibels). This allows the animals to perceive objects over distances never recorded to be further than 20 meters. https://pubmed.ncbi.nlm.nih.gov/22978903/
Regardless bats have also specially adapted receiving organ devices. The ...
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Yes, Absolutely!
Not only can you do such a thing, but in fact boatloads of alternate metric theories of gravity have been proposed both before and after Einstein came out with GR. For instance, the first metric theory of gravity was actually due to Nordström in 1913. Let's go over what exactly the equations governing GR look like, and then we can dig into ...
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Well you would use general relativity if you really wanted to. However even in a curved universe in the really tiny parts of space and time there would be no curvature even though the whole universe is curved. So special relativity could be used as long it is not used over long distances.
About the universe being self-consistent, well sort but sort of not. ...
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There are some exceptional real worlds cases of humans using echolocation, take a look at https://en.wikipedia.org/wiki/Human_echolocation to see a few. There are videos where people avoid obstacles, sink basket balls and take hikes along rocky paths. In a demonstration in a documentary I can't recall the name of Ben Underwood could even successfully detect ...
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Anecdotally: probably. Compare the Horseshoe Canyon Ranch, which is in the Ozarks. The Louisiana Center for the Blind takes blind trainees there annually, with lots of room for said trainees to wander off unsupervised between (and sometimes during) scheduled activities.
More relevant to the question (it isn't precisely a city carved into a rocky canyon, ...
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If you manage to interact with neutrinos to any practical extent, a lot of possibilities open at once:
Energy from the star neutrinos - the Sun emmits some 15% of its energy in neutrinos, you can harvest them even in some planet's shadow. Hotter-core stars are even better in this regard.
Neutrino sails - to harvest neutrino momentum. If you can interact ...
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The issue with harnessing the neutrino-electron interaction is the cross-sections involved. Since neutrinos are charge-less, and interact only via the weak force (gravity also but that won't help us here), they are more likely to interact with larger particles. For this reason, neutrinos-nuclei interactions are the most common.
While neutrinos can (and do ...
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Neutrinos have, believe it or not, been proposed as a method of spacecraft propulsion - see Morgan (1999). The idea is a bit different from yours (which I believe has not been explored yet), inasmuch as it relies on the production of neutrinos, rather than using existing ambient neutrinos.
This idea utilizes the decay of muons, heavier cousins of electrons.
...
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Yes, in combination with other skills
Your residents are going to use a combination of techniques to navigate. Echolocation is a way of avoiding obstacles, not of navigating over longer distances. In the Wikipedia image below, the bat can tell that there's a box ahead on its left, but the bat has no idea what's on the other side of that box.
If your ...
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Intro
You don't want to change the fundamental constants at least not without change the laws of physics, our current universe (with life) only exists because the physical constants are the way that they are. What will follow is an explanation of what is known as the "fine-tuned" property of our universe.
All physical constants to one degree or another ...
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If the Earth's core were to speed up then the liquid outer core would heat up. As you have mentioned only the core is spinning faster not the whole Earth. This could result in massive friction from the outer core and the mantle. This means more heat and more volcanoes. In the short term it would ruin everything, however in the long term faster Earth's core ...
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Fire, in this case, is two parts. The first is that fire is generated from an exothermic reaction, usually involving oxygen. The second is that what we perceive as heat is just faster moving molecules at least in general.
In addition to this, reactions this fun and exciting are generally not spontaneous unless one or more of the materials is highly ...
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You are changing the activation energy requirements of chemical reactions.
To create a chemical reaction, you need a certain combination of activation energy and compression. Things that burn are chemical reactions that are exothermic that release enough energy to create more exothermic reactions in the surrounding medium. Now that said there are tons of ...
answered May 28 at 21:02
Nosajimiki - Reinstate Monica
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Expanding on Topcode's answer a bit:
Electricity by itself is hard to use in the ways it is often shown being used (control must extend quite a distance to get lightning to behave). On the other hand, there is a concept that lies neatly between fire and electricity, and is manipulable via electromagnetism to boot: Plasma.
What you'd basically need is to ...
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if you're asking of what to do with this power then let me tell you, controlling the movements of particles, in the right hands, is far more deadlier that an arsenal of WMDs.
Heat is an increase in the speed of the particles, but if you can also control Direction then it's a whole different beast.
From the top of my head the things i can do:
sudden ...
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The answer depends on the depth, the distance from the bottom and the distance from the surface.
The explosion goes off, the water vaporizes and you have a bubble.
The bubble is under pressure from the surrounding water and starts to collapse.
The pressure inside the bubble builds up and overshoots the surrounding water pressure, so the bubble starts to ...
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If the person is willing to be picked up, the pincers only needs to slide under the armpits and lift the person like a fork lift. This means the only presure the person should experience would be from thier own body pressing down on the pincer from gravity.
If the person is unwilling there is no exact equation for this since humans will vary so much in ...
answered May 27 at 14:50
Nosajimiki - Reinstate Monica
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6
If you are just relying on friction to hold the human against gravity (meaning nothing piercing in the human body to grapple it), you need to equate the weight of the human to the static friction between the creature's pincers surface and the human surface.
$m_{human} \cdot g = F_{pincers} \cdot \mu_{static}$
From the above
$F_{pincers} ={m_{human} \cdot ...
answered May 27 at 12:48
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I do not believe you can deliver the energy well enough. Your beams aren't perfectly aligned (there is no such thing as a perfectly aligned beam), over that kind of range they will diverge far too much to be a useful weapon.
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I can only think of one threat that might justify such an attack: The red dwarf and stellar remnant era!
This could be an attempt to squeeze a few more billion years out of their corner of the universe. Not only is the end of time an enemy worth such an undertaking, but there is no moving target to worry about; so, timing out your attack over a long ...
answered May 24 at 23:18
Nosajimiki - Reinstate Monica
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1
Unlikely - but Yes
So taking this question to be "Could a planet rotate around an axis in the elliptic and tangential to its orbit?" The answer is:
"Sure - but it takes very specific setup."
So the planets all rotate because the swirling cloud of gas that they formed from rotated. Momentum is conserved, and there is nothing that opposes this motion.
...
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Yes, for a given definition of 'North Pole'.
You see, there are three different 'North Pole's
Geographic North Pole, which is defined as 'the point in the Northern Hemisphere where the Earth's axis of rotation meets its surface' (ignoring precession).
Magnetic North Pole, defined as 'the point on the surface of Earth's Northern Hemisphere at which the ...
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Question: "In my world, some person invents a theory of everything. Is there a way that scientists would test the theory, to prove that its right, instead of some scrabbled equations?"
Answer:
Of course every decent theory can be tested. It must (1) agree with all experiments, and it must (2) explain what is so far unexplained. At present (2020), the first ...
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I'm going to assume that the question you're asking is 'Can the Earth additionally rotate up-and-down?', because, Matthew's answer has pointed out, we define 'up and down' based on the planet's already spinning axis. The only way this question makes sense is that you're asking whether the Earth can additionally spin up-and-down. And the answer to that is a ...
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As you say, Uranus does. All it would mean is that the axial tilt would be 90 degrees. This is unlikely in the course of normal planetary formation, so (as with Uranus) it would probably take a series of impacts early in the planet's history to point its axis in the appropriate location.
Now, if we're talking about Earth, things would obviously look a lot ...
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No. The way we define latitude and longitude is based on the planet's axis of rotation. You can certainly (AFAIK) have a planet with a 90° axial inclination, or (probably) a planet that is identical to Earth except with all the land masses rotated 90°, but unless you completely change the definition of "pole", the poles will, by definition, be stationary w.r....
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Full disclosure - everything factual here I'm about to write comes from the same paper that AlexP quoted in the comments, I'm just going to go over a bit more things. The paper is here if you want to look at it.
Metallic Hydrogen is metastable
Once created, as long as it's kept in the same conditions as it was created in, it's expected to be metastable. ...
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How about futuristic gloves? A "super-battery" not yet invented in a special pair of gloves could create such a strong localized magnetic field that the descender could literally insert his hand into the wall. With one or two hands in the wall, controlling these gloves would make the descent like sliding down a pole.
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I missed my chance. Those guys just said everything. The only thing i could add is that only the outer 3ish planets even have a chance of having a moon, and if you were hoping for a hospitable moon, you're out of luck. They would be too dense and far from the star. Also, due to the roche limit and tidal locking(ohhh boy) the innermost 4 planets... no ...
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I think you're confusing a superfluid with a supercritical fluid given that your temperature and pressure is basically at the critical point for supercritical co2. These are significantly different states of matter.
Liquid matter will typically go through a phase change when heated or decompressed (boiling). Conversely it will go through a phase change when ...
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In school physics classes, a spring is just a spring, and you learn by hanging weights and measuring deflection how to find the constant spring modulus $k$, up to the point where you exceed the elastic limit and your spring deforms into a messy wire. The real world, as with most things, is nowhere near that simple, and engineers can create a bewildering ...
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Just pointing out that no one seems to be thinking about the possibility of climbing down (or up) the corner of a building instead of a flat wall. Still, without hooks of some sort it is not apparent how this would help.
I did have one idea, but it does require them to carry a very long rope (ultrathin, ultrastrong etc.). First, use the suit’s built-in ...
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Suits made of spongy, bouncy material. Ultra squishy polymer.
Suction cup gloves/shoes for scaling walls.
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Three Things
Gravity Engine:
Considering that this is all fictional, make the exoskeleton an armor-like suit, in its core, place a gravity engine/plasma reactor, which will power the suit. This engine could be connected up to every part of the suit. For the higher-ranking officials, throw ina gravity gun too, which could function as a portal gun too - ...
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I posted this as a comment, but then I realized it was also an answer to part of your question implied in the last paragraph, so here it is.
'(putting aside for just one moment relativistic effects)' I put my generation ship in a modified Alcubierre bubble, even though it was not going FTL and I did not need it as a drive, just to eliminate the relativistic ...
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The planet will instantaneously explode.
The earth has a gravitational binding potential of about 2.25×10^32 joules, or the weekly energy output of the sun.
This energy also currently being counterbalanced by potential energy of the compression of rock in the earth which prevents the earth collapsing to a point.
Without gravity, it will all be released at ...
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309 days. 0.126 light years.
AlexP already answered in the comments, as is his wont. I am ok with that. I suspect 4th grade math in Romania was more advanced than 4th grade math in South Dakota.
Also I made a jpeg!
https://www.calculatorsoup.com/calculators/physics/velocity_a_t.php
In this calculator v is final velocity, u is starting velocity, a is ...
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The inhabitants of the ship would know where they are going and know the day and year length of the planet they are going to because of advanced astronomical observations before the ship left Earth.
The most logical approach would be to immediately adopt a clock and calendar compatible with their new home and measure everything against that. The trajectory ...
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You'll be scooping up interstellar medium at significant kinetic energies.
There's two problems: The atoms that hit you will actually accelerate you away from your position (pressure measured in Pa), and of course they'll impose a radiation hazard as you absorb them (radiation dose measured in Gy).
Let's do some math. Let's assume an interstellar medium ...
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It is completely unfeasible for the reasons listed above. What's more, the ship itself would be exploded by stray particles hitting it at 0/.3C relative.
Suppose your ship is tiny, just a cross section of 100 square meters and the trip is 100 light years. The volume of that cylinder is enormous. Every piece of space dust in there impacts your ship at 0.3C ...
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Having 0.3c related to any known macro object in our university pretty much imposes having ~0.3c related to anything else (redshifted objects included, if/when you reach near them).
At 0.3c all those stray helium and hydrogen atoms will behave as both deeply penetrating and ionizing radiation. At 0.3c you will "collect" a lot of them, even in the space ...
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As @Thucydides said, your design is far too complex and dangerous for a rifle-like implementation, it would make much more sense as an artillery-style weapon or like an RPG.
Artillery Style:
If you've watched Clone Wars, you would know about the droid tanks in S1E14 with the biomatter destroying weapon, which was attached to the tank, kind of like a ...
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It is not meta-stable in ambient conditions, but since you're writing about a fictional world, you could add some form of futuristic containment chamber that would stabilize it. For the thrusters, you can add Cesium to the metallic hydrogen and use a magnetic field to prevent the exhaust from coming into contact with the nozzle. This thruster, would only be ...
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You might be interested in reading up on the Bereakthrough Starshoot program. The concept is to send a thousand nano light sail spacecraft each with a camera, to Alpha Centauri, at 0.2c taking approximately 50 years, propelled by a laser beam from earth. One way only, of course. They would be protected by a thin, light ablative coating to protect them from ...
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Your astronaut would be protected in the same way as the ship.
It is bad to be hit by a very fast piece of stuff. Very bad if you are alive, but also bad if you are not alive and you get hit over and over all the time. The latter is the case for your ship. Pieces of space dust and particles are plowing into it and ablating it.
And going right thru it. ...
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Talking about any speed is meaningless unless a reference frame is used. Since you cannot sense your own speed, you must use objects as reference points. For the sake of the question, lets assume that your heroes started on a planet, which is located in galaxy not much different than our own. To accelerate to 0.3c relative to the star you started on would ...
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Expanding foam
An aerosol of highly expanding foam, which they squirt at the ground below them as they fall. They therefore land into a column of foam which dissipates their energy as they land.
They can squirt more or less depending on how much speed they need to loose.
The foam would be pretty unstable – it only needs to last a couple of seconds – and ...
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The idea of springs or pogo sticks, already proposed by Willk and Darrel Hoffman is interesting. Let's do the maths.
The main problem is the sudden deceleration: it's not the fall that kills you, it's the landing. We can limit this deceleration using two methods.
Minimizing the terminal velocity: the skydiver should be in a belly-to-earth, face down ...
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