16
votes
Could the human body feel the sudden disappearance or end of a gravitational force?
Firstly, the sun can't just "disappear". Even if it were converted by magic into "pure energy", that energy can't go anywhere faster than the speed of light, and Energy has ...
- 116k
12
votes
Do tidal forces on moons cause them to emit gravitational waves?
Yes, but the effect is tiny
Tim Rias (in a comment below) calculates it to be $10^{-18}$ Watts. (see a paper about doing a similar calculation for neutron stars)
Bodies that have spherically ...
- 116k
12
votes
Are gravitational waves emitted equally in all directions?
The gravitational wave strain is not isotropic. More power is emitted (per unit solid angle) along the orbital axis of the binary than in the orbital plane.
For a circular orbit (and they tend to be ...
- 146k
11
votes
Why do we say that gravitational waves travel at the speed of light, when they can escape a black hole and light cannot?
Gravitional waves CAN'T escape a black hole; nothing that carries information can escape. The event Horizon is one way.
The gravitational waves don't come from the singularity but instead come from ...
- 959
11
votes
Accepted
Joseph Weber's aluminum cylinder
The concept of the "resonant bar" detector for gravitational waves is that you get your cylinder of material to oscillate at its resonant frequency when pinged by a gravitational wave source....
- 146k
10
votes
A mysterious signal at 14.2054 µHz
No, because the strain amplitude from this binary is vanishingly small compared with variations in atmospheric pressure due to a variety of mechanisms at frequencies similar to the expected frequency ...
- 146k
9
votes
Radiation pattern of a GW source
Gravitational waves are tensor modes that are, in general, a mixture of two orthogonal polarisation states known as plus and cross.
By analogy with electromagnetic waves, you can refer to a wave ...
- 146k
6
votes
Accepted
Gravitational wave for Solo mass system
Suppose you have a mass $m$ moving up and down along the z-axis according to:
$$ z(t) = A \cos\omega t $$
The traceless part of the quadrople moment tensor then has components
\begin{align}
I_{xx}^T &...
- 2,511
5
votes
Is it possible to detect gravitational lensing of both light and gravitational waves originating from the same event?
Yes; typically, if the light is lensed, the gravitational waves are also lensed, and vice versa.
The main exception is if the lens is small. The current observatories, LIGO/Virgo/KAGRA, are sensitive ...
- 4,260
5
votes
How far can a gravitational-wave pass through space?
Till infinity
Your question is based on the false premise that gravitational waves require energy to propagate through space and after a certain distance, the waves lose energy and disappear, which is ...
- 2,585
5
votes
Gravitational wave intereference
Gravitational waves are small perturbations in the spacetime metric caused by specific types of acceleration by masses. The gravitational attraction between masses is always present, regardless of ...
- 146k
5
votes
Accepted
What is the formula that shows that gravitational waves can carry information and data?
Obviously they can, in the sense that at least the presence or absence of a gravitational wave can be detected. Hence you could send information by generating one or not, for example by either ...
- 14.1k
4
votes
Accepted
Do collisions of stars still undergoing fusion reactions produce gravitational waves?
Although any binary pair of bodies will produce gravitational radiation, our current technology is only able to detect very powerful source of GW radiation.
When a pair of black holes are in their ...
- 116k
4
votes
What produces gravitational waves with "periods between about 100 - 8000 seconds"?
Says @uhoh “I'm curious how the strain scales with M”
If $m_1$ and $m_2$ are the respective masses of an orbitally bound binary body, and we define $M_c$ as the chirp mass:
$$M_c=\dfrac{(m_1 m_2)^{3/5}...
- 1,720
4
votes
Accepted
Gravitational-Wave Strain and Power (watt/square metre)
Some inital considerations. The total energy would depend on the length of time that the wave was continuous for, and the total area through which the wave passes. That is there is no hope to find ...
- 116k
4
votes
is there any direct method to calculate gravitational wave frequency if the source mass is known?
If you have a system containing two black holes with masses $m_1$ and $m_2$, you can calculate a quantity called their chirp mass,
$$
\mathcal{M}_c = (m_1 m_2)^{3/5} / (m_1 + m_2)^{1/5},
$$
which is ...
- 591
4
votes
When gravitational waves pass through a star or gas cloud do they cause mixing of plasma and gas?
The strain of typical gravitational waves from black hole mergers is on the order of $10^{-21}$. This means that a length of 1000km is compressed and stretched by about the size of one proton.
That is ...
- 116k
4
votes
Accepted
How far can a gravitational-wave pass through space?
In addition to the decrease in the vacuum due exclusively to the distance from the source of the gravitational wave, the gravitational wave undergoes an additional damping when it passes through ...
- 1,720
4
votes
Are gravitational waves emitted equally in all directions?
As a supplement to @ProfRob's answer.
The answer there only takes into account the leading order contribution coming from $\ell=m=2$ quadrupole mode. For binaries that are far from merger, and merging ...
- 2,511
4
votes
Gravitational waves vs. "normal gravity"
Acceleration isn't a property of spacetime per se. Two test particles at the same location can have different instantaneous accelerations, so just knowing that there is a passing gravitational wave ...
- 3,498
3
votes
Could the revolution of super-massive black holes around each other create a pulsar-array gravitational wave signal despite 'final parsec' problem?
TL;DR: We do have gravitational wave emission from supermassive black hole binaries (SMBHBs) at larger separations, but a background created from solely those binaries won't have the characteristic ...
- 36k
3
votes
Do all orbits emit gravitational waves?
All orbits as you would normally think of them emit gravitational waves. You mention an axially symmetric orbit. A hypothetical rotating rigid hoop would not, since the distribution of mass is not ...
- 3,689
3
votes
Accepted
bent space-time by Energy can radiate gravitational-wave?
General relativity makes no distinction between "mass" and "energy". Mass is just one form of energy, a form that happens to be intrinsic to certain particles.
For example, a ...
- 116k
3
votes
Effect of a passing gravitational wave
I suspect you still haven't clarified your question sufficiently.
Gravitational waves are transverse so there is no stretching and compression in the direction they are propagating.
- 146k
3
votes
Gravitational-Wave Strain and Power (watt/square metre)
As explained in the thread How does the gravitational wave strain from a rotating binary depend on the chirp mass, frequency and distance & what a short derivation looks like?
If $m_1$ and $m_2$ ...
- 1,720
3
votes
From where does the energy for gravitational waves come from?
Two black holes starting far apart have gravitational masses $M_1$ and $M_2$ (i.e. the masses you would put into the formulae for their Schwarzschild radii).
When they merge they form a black hole ...
- 146k
3
votes
Do tidal forces on moons cause them to emit gravitational waves?
While JamesK's answer works hard and goes to great effort to emphasize that the effect is really small, so as to dismiss the effect as (humorous hat tip to Douglas Adams):
The effect is small, You ...
- 31.4k
3
votes
Could the human body feel the sudden disappearance or end of a gravitational force?
No, the human body couldn't practically feel the sudden disappearance of a gravitational force
Humans are able to feel because different accelerations applied to different parts of the body cause it ...
- 131
3
votes
Gravitational waves vs. "normal gravity"
A gravimeter gauges the Earth's gravitational force by measuring the resistance it imposes on free fall. Technically, it is not measuring acceleration due to gravity, it measures the upward force ...
- 3,318
2
votes
What produces gravitational waves with "periods between about 100 - 8000 seconds"?
A gravitational wave period between 100 and 8000 seconds corresponds to a frequency between 0.8 mHz and 60 mHz. This is roughly the frequency band that will be targeted by the LISA space-based ...
- 2,511
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