Do you believe in gravity?

[numinus]

I'm sorry but you are incorrect about flux. Flux lines have meaning only for static configurations (Nothing is moving). No kind of influence of fields travel at faster than the speed of light. It is the nature of relativity.

The influence of gravity no matter what theory you use cannot travel faster than the speed of light. That speed is intrinsic to the nature of space and time. Gravity waves that could happen from exploding nebula would reach us at the same time as the visible light. Hence both travel at the speed of light.

Did you think you were talking to a *****?

In newtonian mechanics, it is assumed that there is such a thing as a fixed and absolute reference frame and the gallilean transformation holds.

Of course, special relativity states that there is no such thing as an absolute reference frame. And general relativity takes into consideration accelerated reference frames. The conclusion, gravity is NOT flux. It is space-time curvature.

Which prompted the question -- is it gaussian flux or what?

You might want to read this:

http://en.wikipedia.org/wiki/Speed_of_gravity

Newtonian gravitation

Isaac Newton's formulation of a gravitational force law requires that each particle respond instantaneously to every other massive particle irrespective of the distance between them. In modern terms, Newtonian gravitation is described by the Poisson equation, according to which, when the mass distribution of a system changes, its gravitational field instantaneously adjusts. Therefore the theory requires the speed of gravity to be infinite.

http://wugrav.wustl.edu/people/CMW/SpeedofGravity.html

If we could measure the effects on the Shapiro delay to order (v/c)^2, then we could test the speed of gravity. But these effects would be at the thousandths of a picosecond level, hopelessly small.

The real way to measure the speed of gravity is to detect and study gravitational waves. By comparing the arrival of a gravitational-wave signal with that of an electromagnetic signal from an astrophysical source, one could compare the speed of gravity to that of light to parts in 10^(17).

 

[numinus]

I'm just guessing that the accuracy of measurement available to us through your suggested experiment will not be adequate to determine whether gravity works instantly over distance or not.

Okay, well I tried your experiment, but somebody had to run the stopwatch so I threw Nums out the window and he simply floated off into the ozone.

It is so amusing reading the conversation between boneheads. It gives one a general idea on how much rational thought one needs to put in responding to them.

Duh?

 

[Dr.Who]

Two questions: what has germ theory got to do with environmentalists (liberal or conservative)? And do we have actual proof of gravity acting instantaneously?

The wackos in the alternative health industry tend to be liberal environmentalists also. Ever heard of homeopathic "medicine" ? It has no active ingedients!

Not that the right doesn't have their own wackos who don't believe that vaccines ever work.

 

[Lagboltz]

Did you think you were talking to a *****?

C'mon. You should know better by now to not start a contentious post begging the question like that.

I was responding to this quote of yours:

Post #74
When you say it is a gravitational 'field', then you assume it is some sort of gaussian flux, like magnetic and electro-static fields

Someone versed in physics would assume no such thing.
1) The term "gravitational field" is liberally used in texts and papers on relativistic gravitation as well as Newtonian gravity. So the word should not be construed to imply classical physics only, as you did.
2) Also you should also realize that the influence of electromagnetic fields travels at the speed of light. A paradox in Maxwell's equations led Einstein to resolve it with special relativity theory.

The real way to measure the speed of gravity is to detect and study gravitational waves. By comparing the arrival of a gravitational-wave signal with that of an electromagnetic signal from an astrophysical source, one could compare the speed of gravity to that of light to parts in 10^(17).

Right. That is exactly what I was referring to when I said, "Gravity waves that could happen from exploding nebula would reach us at the same time as the visible light."

You might want to read this:
http://en.wikipedia.org/wiki/Speed_of_gravity

I didn't read that, but I have read "Relativity, The General Theory" by J.L. Synge some time ago in grad school.

As I said, the problem with flux (or the potential for action from a distance) is that they are instantaneous -- that is, flux lines travel through space at infinite speeds.

You should know that flux lines do not "travel" at all. They are merely a visual representation of the direction of force a small particle would experience at some point in space, assuming everything is static.

 

[Mare Tranquillity]

It is so amusing reading the conversation between boneheads. It gives one a general idea on how much rational thought one needs to put in responding to them.

Duh?

Sometimes it seems that Mr. Duh? has replaced our close personal friend Nums. Not that it makes much difference though because neither of them has any sense of humor or even a touch of humility or compassion--Hell, not even a smidgeon of civility. Oh well, love the sinner, hate the sin...

You should be flattered that I chose you for the experiment, I could have used Lagboltz and you wouldn't have gotten the mention in my article.

 

[numinus]

C'mon. You should know better by now to not start a contentious post begging the question like that.

I was assuming you had some sort of intellectual honesty. Is that assumption wrong?

I was responding to this quote of yours:

Someone versed in physics would assume no such thing.
1) The term "gravitational field" is liberally used in texts and papers on relativistic gravitation as well as Newtonian gravity. So the word should not be construed to imply classical physics only, as you did.
2) Also you should also realize that the influence of electromagnetic fields travels at the speed of light. A paradox in Maxwell's equations led Einstein to resolve it with special relativity theory.

And I was responding to this:

"Gravity isn't a physical thing, it's a force that attracts two objects together with a gravitational field, put plainly."

Clearly, the poster meant a vector field, which is the equipotential gradient of a gaussian surface -- hence dependent on flux.

In relativistic gravitation, there is no force due to gravity. It is explained as inertial motion along space that is curved according to a time-dependent scale factor -- which is better explained in terms of mathematical tensor fields.

So, I do not know if you are simply fishing or it is your intention to argue every minute detail.

Right. That is exactly what I was referring to when I said, "Gravity waves that could happen from exploding nebula would reach us at the same time as the visible light."

Apparently not. It is either a little over the speed of light or it is much much more than that -- depending on who you are reading. Personally, I haven't had the time to examine the finer points of that experiment.

I didn't read that, but I have read "Relativity, The General Theory" by J.L. Synge some time ago in grad school.

You should know that flux lines do not "travel" at all.

That is merely another way of saying it is 'instantaneous'. I have no intentions of arguing that with you.

They are merely a visual representation of the direction of force a small particle would experience at some point in space, assuming everything is static.

So are tensor fields, if you think about it.

 

[Mare Tranquillity]

The wackos in the alternative health industry tend to be liberal environmentalists also. Ever heard of homeopathic "medicine" ? It has no active ingedients!

Not that the right doesn't have their own wackos who don't believe that vaccines ever work.

The placebo effect has no active ingredients but it works. Yes, I'm familiar with homeopathis medicine and it works for some people, so does acupunture, so does prayer. When we're dealing with the power of the human mind we probably need to be less sweepingly critical.

I had a friend once who observed that everyone becomes an environmentalist at some point: when they can't get clean water to drink, when they can't breathe the air without choking, and when they have nothing fit to eat. Liberal or conservative is irrelevant at that point.

 

[numinus]

Sometimes it seems that Mr. Duh? has replaced our close personal friend Nums. Not that it makes much difference though because neither of them has any sense of humor or even a touch of humility or compassion--Hell, not even a smidgeon of civility. Oh well, love the sinner, hate the sin...

You should be flattered that I chose you for the experiment, I could have used Lagboltz and you wouldn't have gotten the mention in my article.

Why should I be flattered if you mention me at all, hmmm? I don't even find your opinions credible.

 

[Lagboltz]

In relativistic gravitation, there is no force due to gravity. It is explained as inertial motion along space that is curved according to a time-dependent scale factor -- which is better explained in terms of mathematical tensor fields.

Yes, I know, I wrote a term paper on that.

So, I do not know if you are simply fishing or it is your intention to argue every minute detail.

I'm sorry if I misconstrued you. You have an awkward way of saying things, and it is hard to know what you are thinking.

Originally Posted by Lagboltz
"They are merely a visual representation of the direction of force a small particle would experience at some point in space, assuming everything is static."
Numinus:
So are tensor fields, if you think about it.

Again I don't understand what you are getting at. I wish there was a visual way of viewing tensor fields, but the local field at each point is a matrix and not a vector and I don't see how one could represent an area of tensor fields as a picture on a piece of paper.

 

[Mare Tranquillity]

Why should I be flattered if you mention me at all, hmmm? I don't even find your opinions credible.

I don't find many of your opinions credible either, but am I mean to you? No. And here I am sharing credit for my research with you and you're unhappy about it. You were the rat in this experiment and I gave you credit for that--why so sour? Maybe you should stop putting lemon juice on your corn flakes in the morning.

 

[Lagboltz]

You should be flattered that I chose you for the experiment, I could have used Lagboltz and you wouldn't have gotten the mention in my article.

You should have thrown me out the window. A lag bolt hits the ground with a vibrant "ping". A numinus would be a rather unpleasantly sounding splat.

 

[PLC1]

Why should I be flattered if you mention me at all, hmmm? I don't even find your opinions credible.

Have you tried applying the derivation of heisenberg's uncertainty principle to Mare Tranquility's opinions?

Maybe if you do, you will find them more credible.

 

[Mare Tranquillity]

You should have thrown me out the window. A lag bolt hits the ground with a vibrant "ping". A numinus would be a rather unpleasantly sounding splat.

Actually he floated away into the ozone from whence he came. I wouldn't throw out a lag bolt, do you come with your own tapered, lead shield?

 

[Mare Tranquillity]

Have you tried applying the derivation of heisenberg's uncertainty principle to Mare Tranquility's opinions?

Maybe if you do, you will find them more credible.

Algebra in Navajo might help too.

 

[Lagboltz]

Actually he floated away into the ozone from whence he came. I wouldn't throw out a lag bolt, do you come with your own tapered, lead shield?

Only when I'm formally dressed.