speed of gravity

[RideFree]

Originally posted by: Born2bwire

:roll:

Obviously, time will tell...


[/quote]

30 years wasn't enough?[/quote]"...time will tell" was in reference to :shocked:, not the reference to 1977.

 

[Orbitboater]

Is my observation correct that the most recent post to this thread is Mar 10, 2008. If so, I wish to re-establish this thread- responses?

 

[MrDudeMan]

Is my observation correct that the most recent post to this thread is Mar 10, 2008. If so, I wish to re-establish this thread- responses?

I'm also curious if new information is available that would contribute to this discussion.

 

[SOFTengCOMPelec]

Is my observation correct that the most recent post to this thread is Mar 10, 2008. If so, I wish to re-establish this thread- responses?

This is my response from 2008. It is being sent using gravitational waves, which are being bounced from a star/planet, about 4.5 light years away.

So if the gravity waves, are travelling at the speed of light, the post won't come through until about the beginning of July 2017.

N.B. This is my SECOND attempt at posting here. My first, was accidentally sent in the wrong direction, so instead of going forwards in time, to 2017 (from 2008), it went BACK in time (by about 4.5 years), and ended up being published in 2003!

See here:
https://www.newscientist.com/article/dn3232-first-speed-of-gravity-measurement-revealed/

 

[Mark R]

I'm also curious if new information is available that would contribute to this discussion.

There is, from the detection of gravity waves by the LIGO instrument.

Under current models, if gravity travelled slower than the speed of light (because it was carried by massive gravitons), then you would expect the velocity of gravity waves to depend on wavelength, a phenomenon known as dispersion. The gravity wave signal observed shows undetectable dispersion compared with mathematical models of a black hole merger suggesting an upper limit to the graviton mass, and a speed of gravity including c within the error bars.

It's a pretty indirect observation and makes a ton of assumptions, but interesting nonetheless.

 

[Mark R]

I just thought I'd post an interesting update, as no one else seems to have done so yet.
A subsequent gravitational wave observation (GW170817) of binary neutron star merger and the timings of the corresponding near-simultaneous optical/gamma ray observations from the distance of the source at 1.3e8 ly has provided an extremely narrow constraint for the speed of gravity (better than 1.0 +/- 1e-15 c)

A nice description of the data and calculation can be found here:
https://arxiv.org/abs/1710.06394

 

[DigDog]

i've been thinking about this and i'm not sure how you would calculate this.

Let's say that you have an object and this object is at location 1. Then we imagine another location called location 2. You want to test the speed at which the gravity generated by an object in location 2 affects an object in location 1.
However, the object at L1 is already affecting the object at L2.

So we remove the object at L2. We measure the gravity without this object present, and then we add a new object to L2. HOW?

HOW do we bring an object at any distance of another, at any speed superior to C ? How can we have mass suddenly appear?

i guess you could potentially calculate vector. if a moving mass at L2 has X effect on L1, then when the L2 moves to L3, the effect will now have a different vector.

i really haven't thought about this enough, but the existence of gravity waves being actual waves (i,e, ripples) possibly means that space is not rigid, and therefore gravity does not move instantaneously. However, C seems like a good guess. The concept of C isn't an actual speed, it's a time-related, infinity concept.
Remember that quantum locking doesn't happen at speeds higher than C .. it just travels outside of space. I'm guessing that, if FTL events were to happen (such as a universe impacting with another universe, for as unlikely as that sounds) we wouldn't really experience all of it, only the portion which can be represented by C.

 

[John Connor]

I always thought the speed of gravity was 9.8 Newton meters per second or something like that.

Could gravity be sped up? Like in a black hole?


Edit-

"9.8 metres per second squared, or the equivalent 9.8 N/kg."

 

[VirtualLarry]

HOW do we bring an object at any distance of another, at any speed superior to C ? How can we have mass suddenly appear?

http://nautil.us/issue/54/the-unspoken/physics-has-demoted-mass

Maybe Mass isn't real?

 

[DigDog]

i'll read that later tonight, possibly.

edit: i've actually read that months ago. it's not shocking.
we used to think that atoms were weird because they were not solid. now it's quarks. it's still mass, it still feels solid.
if we manage to prove some emerging theories that the universe is .. "not real" .. hmm .. it's really hard to phrase it without sounding like a moron .. essentially, that reality is statistical .. that is going to be an great advancement, but it won't change how we perceive the world. a quantum foam is still a brick when you look far enough. a brick is a bunch of empty space and statistics when you look close enough.

 

[Mike64]

http://nautil.us/issue/54/the-unspoken/physics-has-demoted-mass

Maybe Mass isn't real?

I'm not getting metaphysical on you but, define "real".

 

[mxnerd]

Most portion of mass is from energy.

 

[ElFenix]

Most portion of mass is from energy.

the equation was originally presented as m=e/c². in which the relation between energy and mass is more apparent.

 

[shortylickens]

I always thought the speed of gravity was 9.8 Newton meters per second or something like that.

Could gravity be sped up? Like in a black hole?


Edit-

"9.8 metres per second squared, or the equivalent 9.8 N/kg."

On EARTH, the FORCE of gravity accelerates objects at 9.8 mps^2. But thats only one massive object and while its helpful to analyze the rest of the universe, its not all there is to know.

 

[mxnerd]

the equation was originally presented as m=e/c². in which the relation between energy and mass is more apparent.

It just shows that how ingenious Einstein is!

 

[WHAMPOM]

After doing a rather exhaustive online search on the topic of gravity, gravitational waves, and the speed of gravity, I've concluded that the "speed of gravity", i.e. the time it takes for a change in a large gravity mass to influence another mass, must be significantly faster than the speed of light.

1. Calculations of planetary orbits assume an instantaneous force of gravity. For example, Mars comes to its closest point with Jupiter, there is no delay in the gravitational effects. There is some anectdotal evidence that when assuming gravitation force is delayed due to it being purportedly the speed of light, that those orbital calculations break down quickly and are woefully inaccurate. Hence why all orbital calculations which take gravity into account assume it is instantaneous, and the most accurate planetary orbit calculations are based off gravity itself with no field delay.
2. While the earth does see via visible light a sun position that is ~8 minutes old, the earth does not orbit the position where the sun was ~8 minutes ago, it orbits the actual position of the sun.
3. "But the gravitation field moves along with the sun/jupiter/other massive object, thus it is always there and updated, that's why we don't see a delay." This is essentially the same false myth about swinging around a pole that is a lightyear long and expecting the end to be going faster than the speed of light. Think about it, if the gravitational field of the sun is updated at the speed of light, Pluto which is many billions of miles away won't see that graviational field update for quite some time, and its orbit will either decay or expand. Why? Because the sun moves, and a pretty good distance in fact. So if the speed of gravity is C, then the gravitational field emanating from the massive object cannot be updated faster than that.

Hence the speed of gravity is much faster than the speed of light. I won't theorize that it is infinite/instantaneous, though quantum entanglement is supposedly instantaneous, so there could be some precendence.

-------------------------------------------------------------------------------

Update March 1, 2008

Space.com - "Pioneer anomaly" reers its ugly head again, defies current gravity models

All that means is the orbiting planets are in a continuous game of catch-up with the Sun's moving center of gravity as it revolves with the galaxy. Which explains why there is no such thing as a perfectly circular orbit.

 

[Orbitboater]

A posit: When any atom comes into existence, it exhibits "mass". That presence of "mass" expands the space-time continuum (STC), in all directions around that atom, and the expansion of the STC around that atom continues into the STC, at the Speed of Light. Note: The Speed of Light will vary with the conditions in the STC, such as large bodies of mass.

Furthermore, while that atom exists, the expansion of the STC around that atom nears a steady-state, "near" the atom, while the expansion of the STC continues indefinitely into infinity.

How well accepted is this posit generally?

 

[DigDog]

i hereby give this thread my allotted weekly free bump

 

[Micrornd]

Since this post was first started, NASA has confirmed that photons striking the surface of it's probes/satellites (and other objects in space) also produce a measurable effect on their flightpath.
Might be something worth considering.