Questions tagged [gravity]
Questions regarding the attractive force which exists between any two bodies of matter.
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Is it accurate to say that general relativity reduces to Newton (inverse square law) since both are derived using geometry?
I once asked a similar question and got a very good mathematical answer, but I'm trying to find one that doesn't involve equations for a lay person. I have been reading how Einstein had to develop the ...
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Dark Matter's effect on galaxy structure
One "fun fact" that's always been, well fun. Is despite what most assume, our sun does not orbit a supermassive black hole or any object at the center of our galaxy.
Recently I read an ...
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Question about how it's possible for black holes to have gravity and a possible resolution [duplicate]
1. Assumptions
1.a: gravity propagates at c (maximum)
1.b: gravitational fields cause time dilation
1.c: escape velocity at the event horizon is c
1.d: gravity "warps" space-time, but in ...
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How to turn find velocity dispersion from radial velocity
In the above given picture Vi is the velocity of the i-th galaxy in the cluster while Vm is the mean velocity of a galaxy in the cluster. and V i,r is the radial velocity of the i-th galaxy and V m,r ...
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Concerning a binary system of stars/planets/black holes could one of them be ejected before eventually merging or colliding?
I was having a discussion with an undergraduate student of physics about binaries and their interactions with external celestial bodies (which could cause the ejection of one of the members in the ...
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Gravitational recoil with stars/planets...?
When two black holes are merging, the resulting merge can be ejected if one of the black holes had less mass than the other one, so the gravitational waves emitted by both of them is unbalanced, and ...
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Is it possible to detect gravitational lensing of both light and gravitational waves originating from the same event?
Is it theoretically possible to detect gravitational lensing of both light and gravitational waves, when both originate from the same source/event (merger of two stellar black holes or merger of two ...
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What is the shape of orbit assuming gravity does not depend on distance?
We know that the orbit of the earth is elliptical considering the force of gravity is inversely proportional to the square of the distance. But assume that, gravity does not depend on distance. ...
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How do primordial black holes are able to have an event horizon?
How do primordial black holes have an event horizon?
Sorry for the stupid question, but I know primordial black holes have just a handful of mass in a cosmic scale compressed in a singularity. But if ...
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How can Aggregation of Gravitational Fields of subplanetary solar objects improve our understanding of the motion of the planets?
If we imagine magnets on a table as a simplified analogy in regards to gravitational attraction between objects, then it may be demonstrated that when three objects are placed in a row labeled in ...
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Modelling dark energy as a potential?
Dark energy is the cosmological constant.However can we model dark energy as some form of field with a corresponding potential?
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Can the gravity of objects entering the observable universe be detected?
As time passes, we will be able to see objects that are further away, as their light eventually reaches us. Since gravity also travels at the speed of light, would we be able to detect when a super ...
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How does superfluid dark matter keep stars orbiting at high speeds in galaxies?
According to A paper on Ultra-Light Dark Matter, Superfluid dark matter is a kind of Bose-Einstein condensate. But how does it help stars keep their high or velocities in galaxies. Can somebody ...
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Lagrange points and Laplace equation boundary condition
I have been reading about Lagrange points and Lagrange regions and how we can apply Laplace's equation for these regions however which are the boundary conditions of the Laplace equation at these ...
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Gravitational-Wave Strain and Power (watt/square metre)
If we detect a gravitational wave with a strain of, for example, $h=10^{-20}$, what is the flux of power carried by this wave, in SI units, $W/m^2$ ?
How can flux of power be calculated for a given ...
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Are short-period comets more stable (in their orbits) than long-period ones?
Why the sharp distinction between short-period (P) comets of less-than-200-year orbits and those (C) with even slightly longer ones?
To explore the possibility that it has to do with stability, I will ...
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Eccentricity with a law of gravity different from the classical one
How can I calculate the eccentricity of the orbit of a planet (with mass equal to that of the Earth) around a star (with mass equal to that of the Sun) assuming that the force of gravity is given by ...
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Velocity of the object in Binary system
how to i can calculate the velocity of the object? If i know the distance of the object from the center of mass, and i know distance between the two (identical) ellipse center... (the two object has ...
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Does the Earth constantly lose mass?
The Moon is orbiting the Earth in a circular motion. To keep any object in a circular motion we need energy. Hence, does the Earth lose energy by pulling the Moon? In that case, does the Earth's ...
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How would "dark matter", subject only to gravity, behave?
If we were to hypothesise that the Universe contained a significant mass of "dark matter" particles subject only to gravity, presumably general relativity would give us a good idea of how ...
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At what point above Jupiter is the gravity Earth-like?
Jupiter is a massive planet. We get it. However, we have also heard that, since it has such a huge radius, at different elevations it is possible to experience different levels of gravity. We hear ...
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How light could the lightest objects able to exist in a stable orbit be?
Below a certain M1M2, gravity would get so weak that the masses wouldn't be able to orbit each other with stability, as other factors would overwhelm them, even in the quietest, stillest places in the ...
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Does a planets mass affect its gravitational pull? Let's say earth increased or decreased in mass could that theoretically affect gravity?
This was a random thought I had, and I can't seem to find any answers. I was thinking that if the Earth shrunk that could possibly cause an increase in ...
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Can a satellite at lagrange point be stabilized with gravity gradient?
Assuming that the satellite is big enough and the it is at the Lagrange point between the Earth and the Sun, can this satellite be stabilized with gravity gradient? (which means, can this satellite ...
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What would happen if all water on earth including the oceans was placed evenly over the atmosphere of Earth? [closed]
Would that massive water body sit on top of the atmospheric bubble or would it fall to the ground? Would it rain water or fire instead? Would we see the skyes red instead of blue? What would be the ...
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How to call the fear of no gravity? [closed]
In opposite to barophobia I can't google out a fear of the case, when a man is taken out of the ship and he must go through the spaceship's docks and he can't get the direction of gravity - in the ...
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Kinetic energy in cosmology?
Spacetime expands at an accelerated rate due to the Hubble flow. In many papers that I've read, objects coupled to the Hubble flow are treated as if they have some velocity and kinetic energy ...
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What kind of effects would two moons have on an earthlike planet?
On Earth our moon has several effects: it generates two high and two low tides a day; it slows down the spin of the planet and stabilizes its wobble, etc.
So, what possible effects could two moons, ...
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Is the speed of time much slower on sun surface?
The gravity forces on Earth and Sun is different and in Interstellar, they said something like high gravity slows time. So if we say Sun is N billion years old, that must be earth time but on Sun's ...
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Is frame dragging expected to be quantized in a theory of quantum gravity?
Protons and electrons have angular momentum which is quantized. Would the angular momentum of black holes be quantized in quantum gravity? Would this then affect Hawking radiation?
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The path of a particle in planet's magnetic field doesn't not seem to change with the charge of the particle. Can someone please check what is wrong?
I am trying to plot the path of a charged particle in a planet's magnetic field. For positive and negative charge (β=charge/mass) different solutions/paths are expected. But,I got the same solution (...
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Can objects join the Hubble flow for a given amount of time and then somehow abandon it?
When two objects (e.g. two galaxies) are sufficiently far apart, they join the Hubble flow and they get further away from each other. Normally, this would last "forever" (until, from the ...
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Would gravitational stratification deter carbon-based life on large rocky planets?
Most of Earth's heavy elements are concentrated in its deepest layers, as they're denser than the surrounding silicates and sink to the core. If its overall gravitational pull were substantially ...
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Could we detect dark matter by black holes gaining unexplained mass?
Dark matter is said to interact only gravitationally, so it won't commonly form black holes by itself. But if a black hole is already there, and dark matter encounters the event horizon, it should go ...
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Farthest distance two objects are "gravitationally bounded", considering expansion of the Universe
The narrative is: "on greater scales the expansion of the Universe dominates, but on smaller scales gravitationally bounded objects still stay bounded". But how small is meant by "...
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What is the mathematical condition for the statement: "gravitationally bound"?
When talking about galaxy clusters there is the frequently used phrase "gravitationally bound", f.e. we are gravitationally bound to our neighbor galaxy the Andromeda Galaxy. But how is this ...
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Does gravity extend out infinitely?
The sun’s gravity gets weaker the further out you go, the same goes with the Earth. But even back out all the way to Neptune and Pluto, the gravity is still there. The sun can even keep Sedna which at ...
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Could a rogue comet perturb a frequently occurring meteor shower to the extent that debris falls on Earth...and dislodges satellites?
This is for a work of fiction that I started five years ago. Clever people from Astronomy Stacks answered several questions for me back then. Now that I am in the final edit of this manuscript, I find ...
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Could a super-Jupiter exoplanet in the habitable zone have an axial tilt?
I’m wondering if a massive planet (maybe 10 times the mass of Jupiter) in the habitable zone of a G type star could have an axial tilt similar to earth or if gravitational forces would erode the tilt ...
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Could a planet have a massive crater without collapsing due to gravity / other factors?
A severely destroyed planet is a popular trope in media. Here are a few examples from fiction with pictures (spoiler warning).
A crater with a diameter 1/3rd the size of the planet itself:
Earth (...
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RAMSES fine multigrid Poisson solver fails to converge?
I am working on setting up N-body simulations of galaxy mergers. The initial conditions are generated from the DICE code, and looking at them, they seem very realistic. Unfortunately, when I let ...
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If 16 million kilometers were added to Earth's semi-major axis, what measurable effect would there be on Mars' orbit?
I have some education in astronomy, but nothing extensive in astrophysics. I can follow mathematical procedure with assistance. Procedural responses are most welcome!
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Could the universe expand forever even if there is no force (e.g., dark energy or eternal inflation) pushing it apart?
Matthew O'Dowd specifically and repeatedly states in the PBS Space Time video called, "Why the Universe Needs Dark Energy", that even without taking an expansionary field into account an ...
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Initial state for a 3-body problem to create Figure 8 [ restricted to 2D ]
I've made an n-body simulation solution using the naive algorithm of O(n^2) in my library ChelseaaJS.
I was trying to make some pleasing 3 Body simulations.
I wanna do the 8 figure thing.
I know it's ...
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Can two Stars form an Einstein Ring?
We know that when two galaxies are perfectly aligned they form an Einstein Ring by gravitational lensing but can two stars form it? We know gravitational bending by stars, but can two perfectly ...
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Why does electron degeneracy pressure not stop massive star collapse?
I was thinking a little bit, and never asked myself the following. If white dwarfs do not collapse, because electron degeneracy pressure stops the star from collapsing by its own gravity, and this is ...
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What is Gravitational softening length?
I was reading the Aquarius simulation preprint (Springel et al. 2008) The Aquarius Project: the subhalos of galactic halos as a reference for my internship. I came across the term Gravitational ...
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Calculating the "Turnaround Point," where expansion dominates over gravity
I'm trying to understand the point where the expansion of space dominates over gravity, but I'm coming up empty handed when searching the internet. Specifically, I'm trying to find the math for it. I'...
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What is roughly the Lorentz factor between interstellar and inter-galaxycluster space?
Could someone provide a rough estimate for the average Lorentz Factor caused by gravitational time dilation between some point in interstellar space in our vicinity within the Milky Way galaxy and ...
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How much would you weigh at the equator of the fastest spinning pulsar?
Assuming you have a mass of 70 kg, what would your weight be on the equator of PSR J1748−2446ad?
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