Gravity (from Latin gravitas 'weight'), or gravitation, is a natural phenomenon by which all things with mass or energy—including planets, stars, galaxies, and even light—are attracted to (or gravitate toward) one another. On Earth, gravity gives weight to physical objects, and the Moon's gravity causes the ocean tides. The gravitational attraction of the original gaseous matter present in the Universe caused it to begin coalescing and forming stars and caused the stars to group together into galaxies, so gravity is responsible for many of the large-scale structures in the Universe. Gravity has an infinite range, although its effects become weaker as objects get further away.
Gravity is most accurately described by the general theory of relativity (proposed by Albert Einstein in 1915), which describes gravity not as a force, but as a consequence of masses moving along geodesic lines in a curved spacetime caused by the uneven distribution of mass. The most extreme example of this curvature of spacetime is a black hole, from which nothing—not even light—can escape once past the black hole's event horizon. However, for most applications, gravity is well approximated by Newton's law of universal gravitation, which describes gravity as a force causing any two bodies to be attracted toward each other, with magnitude proportional to the product of their masses and inversely proportional to the square of the distance between them.
Gravity is the weakest of the four fundamental interactions of physics, approximately 1038 times weaker than the strong interaction, 1036 times weaker than the electromagnetic force and 1029 times weaker than the weak interaction. As a consequence, it has no significant influence at the level of subatomic particles. In contrast, it is the dominant interaction at the macroscopic scale, and is the cause of the formation, shape and trajectory (orbit) of astronomical bodies.
Current models of particle physics imply that the earliest instance of gravity in the Universe, possibly in the form of quantum gravity, supergravity or a gravitational singularity, along with ordinary space and time, developed during the Planck epoch (up to 10−43 seconds after the birth of the Universe), possibly from a primeval state, such as a false vacuum, quantum vacuum or virtual particle, in a currently unknown manner. Attempts to develop a theory of gravity consistent with quantum mechanics, a quantum gravity theory, which would allow gravity to be united in a common mathematical framework (a theory of everything) with the other three fundamental interactions of physics, are a current area of research.
Hi there, so I want to know how to get the speed I need to move some object from point A to B, accordint to the distance between points, gravity and height angle.
I means, I have this:
height angle = 40.0
distance from point A to B = 5m
gravity = -9.81
speed = ?
I think that I just need to know...
Homework Statement
An elevator is traveling at 30 m/s just as it touches a cushioning spring. The safety clamps engage at that moment and provide 20,000N of frictional force. The mass of the elevator is 3000kg and the spring constant is 15000 N/m. How fast will the elevator be traveling after...
Hi, what would happen if you took 1 cubic meter of matter from pulsar into empty space what would happen does the matter will expand since there is no more strong gravity does will it explode ? would like to know your answers
I have a major in mathematical physics and mathematics and currently I'm on a graduate course in Physics working on a master's thesis. When I started the graduate course I was going to work on General Relativity and Quantum Field Theory on Curved Spacetimes (QFTCS). It turns out that by several...
Homework Statement
A jet pilot takes his aircraft in a vertical loop. V is 840 km/hr (233.3 m/s) find the min. radius of the loop to that the centripetal acceleration at the bottom does not exceed 6 Gs.
Homework Equations
a = v^2 / r
F = ma
The Attempt at a Solution
I don't know where to...
I was reading this article Why Einstein did not believe that general relativity geometrizes gravity and it seemed rather interesting. So it would be interesting to hear what others think of it.
It suggests that Einstein's view on GR was that it does not reduce gravity to inertia and geometry...
I'd like this issue clarified
I understand that a full nonpertubative quantization of a yang mills gauge theory in 4D is unavailable.
is Dirac quantization of classical theory of gravity e.g GR rewritten Ashtekar Variables
Variables or some variation of the idea, a viable approach to a...
This is something I haven't been able to wrap my head around yet.
In physics, I've always been told that gravity is a force that ALWAYS works between "objects" with mass. Now, it seems clear to me that if a feather and a hammer were to be dropped at the same time on Earth (without air...
How much gravity is needed to dim a light bulb?
Could this exsperiment ever actuly be created?
Also is the shape of a spiral galaxy like ours due to the effect of the supper massive black hole at its center has on all the other stuff in the galaxy ? Or is it because of the effect the black hole...
I have an experimental bent.
I am currently trying to expose the tachyon field (replace with quantum field, zero point or whatever term is currently your favorite). Also, currently trying to use a longitudinal wavelength in place of a conductor to reach the ionosphere and tap its electrical...
Can someone explain why we are certain there is dark matter in our universe?
I understood it like this. At some Point in our recent history we figured out, that according to our math galaxies (or sth like that) wouldn't have developed like they did or wouldn't even stay in 1 Piece since they do...
I was watching a movie called Everything and Nothing. It got me thinking. For the sake of argument pretend that you could make the sun pop in and out of existence. If you were to measure the distance between two points on the other side of the solar system with no sun, then if the sun were to...
How is chaos incorporated into quantum gravity theories, or in theories that incorporate all the known 4 interactions?
I don't believe I've seen a thread where chaos theory is discussed in relation to superstring theories or LQG.
I've seen some papers and dissertations on quantum chaos and...
Homework Statement
Homework Equations
shown above
KE = .5mv^2
KE = Total Work
Total work = Work by block - work by spring
The Attempt at a Solution
Shown above.
Did i do the problem correctly? I'm always unsure if I am doing the problem right
If you had two masses, m_{1} and m_{2}, and you released them in space infinitely far apart, their kinetic energies would satisfy \frac{1}{2}m_{1}v_{1}^2+\frac{1}{2}m_{2}v_{2}^2=\frac{Gm_{1}m_{2}}{r} if they met with a distance r between their centres of mass. This equation therefore tells you...
first thing first i want you to excuse me for my Grammar or spelling cause i am really bad at both !we know that what gives the thing gravity is the mass
the mass warp the space-time fabric
but Jupiter has a low mass than earth
how does it have all this amount of gravity
or the warping in the...
Homework Statement
You hold a small ice cube near the top edge of a hemispherical bowl of radius 100 mm. You release the cube from rest. What is the magnitude of its acceleration at the instant it reaches the bottom of the bowl? Ignore friction.
Homework Equations
ΣF = ma
Fg = mg
The Attempt...
In a physics test in a Norwegian website of a school book, it says following:
True or false?
(1) According to Newton's 3rd Law, the weight of a book that is on a table is just as big, but opposite the force on the book from the table (normal force). FALSE.
(2) According to Newton's 1st Law...
Hi,
I teach a physics class to a group of homeschooled students. Many of them aren't yet at the level of algebra.
Last week we went over Newton's laws and did some experiments to show objects fall at the same rate regardless of mass. One student though, has asked me to explain why the mass...
The reason I made an account is to ask about the effect of gravity from an extra planet hiding behnd the sun. I think that if this was the case we would see much great impacts¿ say like the tides. Would they not be extremely high and low? Nonstop quakes that would be felt across the world? I...
1. The Clock Hypothesis states that the rate of a clock does not depend on its acceleration but only on its instantaneous velocity. This has been experimentally verified at very high accelerations.
2. A clock in a gravitational field experiences time dilation and runs slower that one not in a...
Why there must be a way of including gravity into a quantum theory? What leads scientists to believe that ultimately all the interactions must be subjected to quantisation?
Would that be because we describe all other interactions in quantum theory and so we must include gravity on this...
latest paper
Ghirardi-Rimini-Weber model with massive flashes
Antoine Tilloy
(Submitted on 12 Sep 2017)
We introduce a modification of the Ghirardi-Rimini-Weber (GRW) model in which the flashes (or collapse space-time events) source a classical gravitational field. The resulting semi-classical...
Homework Statement
Two balls are given, the distance between their centers is 8R. Both have a radius of R.[/B]
One ball has a mass of 2m and the other has a mass of m.
The question is: What will be their velocities right before they touch each other
Answer: Vm=√(GM/R), V2m=0.5√(GM/R)
Homework...
https://en.wikipedia.org/wiki/LIGO#/media/File:Simplified_diagram_of_an_Advanced_LIGO_detector.png
The axis on the bottom of the graph depicts frequencies between 20-1000 Hz which are sound waves. Again, how can a sound wave (gravity waves) propagate in the near vacuum of stellar space...
Testing Quantum Gravity
Johan Hansson, Stephane Francois
(Submitted on 19 Oct 2017)
The search for a theory of quantum gravity is the most fundamental problem in all of theoretical physics, but there are as yet no experimental results at all to guide this endeavor. What seems to be needed is a...
GW170817 showed that gamma rays came 2 seconds after gravitational waves. (after 130M years) Are these two seconds uncertainty at determination of difference of these speeds? Or is it possible to explain, why 2 seconds of difference, or is it possible to explain, at least, a part of this...
Homework Statement
[/B]
Hi everyone! So I've got this similar problem as I posted yesterday, but this one
is slightly different due to the presence of gravity:
A particle in gravitational field ##~~g##
starts traveling upward (positive direction) along the y-axis from ##~~y=0##
with the...
Homework Statement
We were given this question on a worksheet last lecture. The question is this:
‘Throw a tennis ball/your pen/some non-dangerous object into the air, straight up (and catch it again), observe its motion. Use your observation to measure the gravitational acceleration due to...
If I compress a spring beyond its most relaxed point it will have more energy and thus by General Relativity produce a stronger gravitational field than the uncompressed spring will. But suppose instead I pull in the opposite direction and stretch the spring beyond its most relaxed point it is...
Hi everyone, today, I have a question about quantum gravity, good to begin with. I used Newton's formula to calculate gravity for nêutron , the result exceeded Planck's radius, the question is: could it be that gravity is not necessarily connected to the mass of a particle, nor with graviton...
Did the 2017 eclipse prove Einstein was right or the jury is still out? I can't find any references to the new measurements and what they proved (or did not).
I thought of another question(s) :) does temperature affect the rate of the decay at all?
Does temperature effect the energy of the decay; in that the energy of the electron anti neutrino would be higher?
Hi all
I read a question on this subject from some time ago but was not satisfied with the clarity of the answer and in the light of recent experimental results I wish to clarify my understanding of this ancient scientific question.
What is the cause of Inertia?
So is inertia simply the total...
If I keep iron fillings on a cardboard with a wire carrying current in some direction, I know that the fillings will orient in concentric circles.But what happens if I keep the fillings on the underside of the cardboard? Is it possible to make them hang in the air against gravity with a...
In quantum gravity, I get 'mixed signals' as regards renormalizability. My state of confusion is being caused, I suspect, by an incomplete understanding of what is covered under t'Hooft's 1972 proof that non-Abelian gauge theories are renormalizable. ( = Nobel Prize 1999).
Specifically, some...
So my first question is :- Is there any quantum theory success to derive the principle of general relativity? and If this happen, Does this mean we succeeded in finding a quantum theory of gravity?.
and My second question is :- Is quantized background-independet theories exists? and If so, is...
(context) I can remember reading about an atomic clock that could show time running slightly differently rates at different heights, due to the differences in gravitation.
Is it realistic to think of it the other way round, ie gravity as an effect of miniscule time rate difference ?
If an...
Hi Guys,
So I am using the following simulation for this activity (Mass and Springs).
The concept I need help with is to understand why when attaching a mass, the spring moves downward when the gravity is zero? If there is no gravity my limited understanding is that spring should not move...
Hi,
Please could someone kindly explain how zero weightlessness is achieved in this aircraft. I have tried to use my own understanding and what I have read online.
My ideas are:
To experience weightlessness the plane must be in freefall so the only force acting on it must be gravity. Since...
In simple examples of throwing a ball upward and observing it's arc, the calculations include a constant vector acting downward on the ball throughout it's flight. Without getting into the complications of that vector changing magnitude with altitude, it does not change with respect to the speed...
Homework Statement
-Two objects of negligable radius and masses M and m are fixed in space at the distance R. Gravity is the only force acting between those two bodies. At some point in time, body of mass m is realized and starts moving due to gravity toward statical mass M.
Find v(x) and...
So, I'm going to learn general relativity but I'm confused in which book I start with
Bernard Schutz book seems excellent but I'm more interested in d'Inverno book,
And Misner/Throne Book Seems complete but its giant and good for reference, So
I think I will go with d'Inverno , but first I need...
Homework Statement
I have two objects that slide without friction on a circle of radius R, oriented in a
vertical plane, as seen on the attached photo.
The heavier object (mass = 3m) is attached to a spring with an unstretched length of zero and spring constant k. The fixed end of the spring...
That is to say, how does time behave in a region of space where multiple gravitational fields cancel out their accelerating effects?
I understand that time "slows down" in a gravitational field, but does this depend on the actual presence of the field, or instead the actual net acceleration...