A Legitimate Gravity question

[xelasnave]

I lifted this from a science daily article..........

Pulsars are small, ultradense stellar objects left behind after massive stars die and explode as supernovae. They typically have a mass greater than that of our Sun, but compressed to the size of a city like Montreal. They spin at staggering speeds, generate huge gravity fields and emit powerful beams of radio waves along their magnetic poles.

http://www.sciencedaily.com/releases/2008/07/080703140721.htm

Does anyone know how the spinning "generates huge gravity fields" according to conventional science... which I guess is General Relativity... or another field of science???

Any guidance appreciated:).

alex:):):)

[xelasnave]

The scientist regards this work as very important.......This new test of Einstein's theory was led by McGill astrophysics PhD candidate René Breton and Dr. Victoria Kaspi, leader of the McGill University Pulsar Group.

full article
http://www.sciencedaily.com/releases/2008/07/080703140721.htm

extract
"However, so far, Einstein's theory has passed all the tests that have been conducted, including ours. We can say that if anyone wants to propose an alternative theory of gravity in the future, it must agree with the results that we have obtained here."

Well I agree ... it seems that motion within the grid can show that higher gravitation will result... now thats a good theory ...seriously any simple explaination would be greatly appreciated as to how they can work out greater gravity by greater spinning (my ideas agree with this strangely).

alex

[DJDD]

I think that these are three distinct properties of pulsars...

1. They spin at staggering speeds
2. generate huge gravity fields
3. emit powerful beams of radio waves along their magnetic poles
:shrug:
cheers,
DJDD

[xelasnave]

Yes you are correct.... it is that spinning generates gravity that caught my attention.

Some spin rates are unbelievable.


alex

[bojan]

Rotation speed has nothing to do with gravity field, as DJDD wrote.

However:
- High rotation speed is the consequence of star collapse (because the rot momentum preservation.. smaller star, higher rotational speed).

- Extremely strong gravity field (close to the surface of pulsar) is also consequence of star collapse (increased density of the star remains).

- Huge magnetic fields are also consequence of star collapse ("compression" of magnetic flux into the smaller volume increases the flux density, which is the definition of magnetic field.
Strong magnetic field = strong influence on moving charged particles => strong radio emissions + whatever else.

[DJDD]

i do not think the rapid spin generates gravity.
:shrug:

[bojan]

And you are 100% right here.

Alex, very often those articles are misleading.. because they are written by people who do not have a clue of what they are writing about, unfortunately. Also, very often the words are not chosen properly.. so this can create additional confusion in general public.

[xelasnave]

Thanks Bojan and thank you DJDD.

Well there is no evidence that spinning changes gravity... I read into the sentence that it did..that was new to me... at least as far as what conventional science says... I wont go into that other gravity idea.
(but spin is relevant in push U) .

Thank you both for you input and help.
alex

[Zuts]

Hi,

The strength of the gravitational field between any two objects depends on the mass and seperation of the objects. It also depends on the pressure and energy of the objects. For example if you have two identical springs you can increase the gravitational field by compressing one of the springs. This causes energy to be added to the system (which is equivalent to mass) and so adds to the gravitational field.

Possibly spinning adds to the angular momentum of a system and so increases the amount of energy and so increases the gravitational field?

Cheers
Paul

[Kal]

When you imagine an object accelerating and approaching the speed of light, it's mass increases and time slows down (relative to the observer, say us here on earth).Now imagine that with a very dense rapidly rotating object like a pulsar?

[xelasnave]

Thats OK I havent a clue either.
I suppose it must be difficult being a scientific journalist specialising in dark matter black holes and general relativity I guess the few opportunities to sensationalise would have to be grabed ... I see some that I find amusing. Still as far as the gravity thing goes current science works on relationship of mass and does not factor in anything for spin.

alex

[bojan]

Not in this case, spinning energy is also conserved (that means the rotational energy of what is left of the star after explosion/collapse).
This energy is insignificant contributor to the grav. field (in terms of E=mc^2)

[avandonk]

You will only get detectable gravitational waves from a collapsing object (super nova) or two orbiting objects that are massive such as two black holes. Most journos know stuff all about science. Your best defence is to study science not the popular press.

In order to detect even a very strong gravitational wave you are looking at detecting something in the order of 10 to the minus 23 of the size of a atom in variation of length of the measuring device. The longer the detector the larger the signal. Stuff all multiplied by a lot is still below the inherent noise currently! Very large laser interferometers are most probably the best bet. At least it will put an upper limit on the magnitude of these waves even if they are not detected. That should not stop us from trying but to be realistic of what phenomena we are studying.

Bert

[xelasnave]

http://www.sciencedaily.com/releases/2004/07/040728090338.htm

Is this trash?

alex

[bojan]

Looks like a very stretchy speculation to me..
But who knows? :-)

[xelasnave]

I like it I can use it:lol::lol::lol:
alex:):):)

[Max Vondel]

Yep; as stated by a few authors, spinning has nothing to do with the gravitational field (unless you subscribe to alien UFO propulsion). A pulsar has an intense grvitational field and it usually spins also. The gravitational field would be the same if it didn't rotate at all. Space tells mass how to move and mass tells space how to curve.
:whistle:

[sjastro]

The space-time around massive bodies (black holes, neutron stars) will change if such bodies are rotated even though the strength of the field does not change.

http://en.wikipedia.org/wiki/Kerr_metric
http://en.wikipedia.org/wiki/Ergosphere

Spinning does effect how a particle will behave in the field, if the particle ends up in the ergosphere.

Regards

Steven

[xelasnave]

I wonder if the prospect of frame dragging does not suggest spinning will increase gravity... something spinning fast will have space time wrapping around it and one would think compressing the grid which is in effect a way of saying gravity has increased. Although I can not demonstrate what I suggest I feel such a view may be demonstratable using the general premise of frame dragging.

alex
alex

[sjastro]

No it doesn't. Rotating a massive object changes the geometry of space-time around the object without affecting the strength of the field.

Charged particles caught in the ergosphere will generate a magnetic field.

Regards

Steven

[xelasnave]

Steven I am still thinking about this and I accept what you say is the way it is... but if the geometry of space time around an object is changed I thought that was in effect our gravity expressed by geometry... I just thought a spinning object could wrap up space time thereby compressing it which is in effect expressing greater gravity... I mean that would seem a reasonable expectation of the frame dragging prospect... AND just the other day..yesterday??? I was reading a lot about black holes and the subject was very much on discoveries of rotations and higher speeds..not one article but heaps..just news but that why I thought about it.

How does a magnetic field fit into a space time description .. I suppose it wont as gravity and magnetism are not united.

alex
alex