Gravitational waves

B

Beercules

Registered Senior Member
Up until the 1960's, there apparently was some serious debate as to whether or not gravitational waves actually existed. Some argued the idea to merely be a mathematical artifact that did not actually describe reality. Today, it seems most cosmologists are convinced on the reality of such gravitational waves. But if these waves did not infact exist, how would changes in the gravitational field be communicated? Would it be instant, like in Newtonian gravity?
 
I have always wondered that myself. It seems that Newton assumed that masses were affected by one anothers gravity instantaneously. It also seems that this question could be solved with a simple experiement though... a number of things could be done but if, for example one put a perfect pendulum in a vacuum or some other sensitive device, the moon or some other gravitational source could be used to measure what direction the device is pulled in comparison to the instantaneous direction of the massive object. I'm sure someone knows whether gravity is instantaneous, and if it is this would surely rule out the chance that it is a wave, as Einstein theorized.
 
While I not qualified to give a firm answer.... this is how I have seen it, and hopefully I will be able to expand the discussion.

I BELIEVE that gravity must be instantaneous. Not in a wave, or in any other kind of form.
reason 1:
Gravity affects things everywhere, whether in a perfect vacuum or not. Now how would a wave be able to transmit its self through nothingness? The only way this would work is with some kind of sub atomic partial not yet known. Waves only transfer through matter, not open space.
Reason 2:
The total and complete lack of a mechanism providing for gravity seems to suggest that it is just "there". Gravity is still one of those real mysteries of science, and even though I have read articles where they claim to have calculated its propagation speed, I don’t really believe them.

I find the best explanation of gravity comes from the Bible,


Colossians 1:17
He is before all things, and in him all things hold together.


I will say more later, I really need to go…. J
 
joel,

Actually i learned today that gravity does have a speed of propogation. But just to let you know, when you said that waves must have a medium to travel through, that only holds for sound waves, NOT light waves. Light does not need a medium to travel through, and this is obvious from the fact that you can see stars when you look up at night, because their light has traveled to you through what is (for the most part) a vacuum. So the argument that gravity can't be a wave because it can travel through a vacuum does not have a sound basis.
 
There is indirect evidence for the existence of gravitational waves, from the spin-down rates of binary pulsars.

<i>Gravity affects things everywhere, whether in a perfect vacuum or not. Now how would a wave be able to transmit its self through nothingness? The only way this would work is with some kind of sub atomic partial not yet known. Waves only transfer through matter, not open space.</i>

Light moves in a vacuum. Why not gravitons (if they exist)?

<i>The total and complete lack of a mechanism providing for gravity seems to suggest that it is just "there".</i>

Isn't General Relativity a "mechanism"?

<i>Gravity is still one of those real mysteries of science, and even though I have read articles where they claim to have calculated its propagation speed, I don’t really believe them.</i>

Why not? It follows directly from relativity.

<i>Colossians 1:17
He is before all things, and in him all things hold together.</i>

So God is gravity? Interesting philosophy.
 
Light can move through a vacuum because it exhibits qualities of both a wave, and a particle

Gravity on the other hand, is not known to be a wave, or a particle.


"Actually i learned today that gravity does have a speed of propogation"

Yes, I have read a few papers talking about that, but so far, I am not much of a believer in it.

if more evidence is provided, then I will of course believe it, but until then I am leaving the door open. But I do acknowledge that as a possibility
 
What does create changes in the gravitational field?

It is a supernova event according to Savov's Theory of Interaction.
 
The movement of mass is a change in the gravitational field. Since everything has mass (or relavistic mass) this includes everything in the universe.
 
Then has to be a gravitational wave background, which is likely to be found at wave lengths corresponding to the scales of the space bodies. As far as I know it is sought at much smaller wave
lengths and so naturally is not found. Am right or wrong?
 
The background is space-time itself. The wave is supposedly a ripple in the geometry of spaceitme, but it isn't really considered a medium. But then, you'll find that whatever proposed fundemental entity you have, cannot be made of any substance.

Apparently, the waves get weaker as they go further from the source, and are already millions of times weaker than the EM force to start with. So as you can imagine, a wave from any distant celestial body would be so weak and quite difficult to detect.
 
Consider the space bodies as multiscale 3D-spiral sources (patterns) of interaction, as shown in Eugene Savov's Theory of Interaction. Then your should look for gravitational waves at their scales (in the about 1000 km range) rather than at the much smaller atomic scales in which you naturally do not find them.

Knowledge make us happy!
 
I'm surprised that the hypothesis of instant propagation does not make some obvious and immediately testable predictions. Prior to Beercules's seal of approval here (no sarcasm intended) I would have assumed that such a hypothesis would fall within 'pseudo-science'.

Can't the matter be solved by looking closely at planetary orbits or somesuch, or are the predicted differences in results too subtle.

This bit may be confused but - if propogation is instantaneous surely we could never know, since any test would require proving that our data/information has reached us faster than light.
 
Last edited:
I think the logic of it was that since it was a mere change in the geometry of spacetime, it wasn't really a signal at all. But I'm still not sure about that.
 
Despite some recent controversy, gravity is nowadays believed to propagate at the speed of light.
http://www.straightdope.com/mailbag/mgravityspeed.html
...two obvious questions: (a) How do we know gravity travels exactly at c? Answer: We don't, but it seems consistent with other things we know. To put it in technical terms, general relativity is only self-consistent if the speed of gravity is Lorentz invariant (that is, the same for all observers), and the only speed for which that works is c. (b) If gravity travels at the same speed as light, is it propagated by waves and particles, as light is? Answer: It seems likely. In fact, the gravitational particle has already been given a name: the graviton.
Click to expand...
There are several minor phenomena that seem to indicate that the speed of propagation might be faster than light, for instance the so-called aberration of gravity; these phenomena are apparently also explained by relativity
(in a way which unfortunately goes over my head).

The various gravity wave detection apparatus such as LIGO and LISA which are expected to give useful data soon will hopefully detect gravity waves from a very long way away and a very long time ago, giving another insight into the early universe.
__________________
SF worldbuilding at
http://www.orionsarm.com/main.html
 
What i don't understand is when they say : "Gravity waves are only produced by accelerated bodies"
But the geometry of the space around a body that moves at constant velocity is changing too. Why this body don't emit gravity waves?
 
You must log in or register to reply here.
Back
Top