Double Pulsar Discovered

jabberjaw writes "Nature is reporting that a set of two pulsars could be emitting gravitational waves. Einstein predicted the existence of gravitational waves in his general theory of relativity, but a gravitational wave has yet to be detected. Find out more about gravitational waves and pulsars at Eric Weisstein's World of Physics."

Comments

At last??

[talonx]

Gravitational waves have always been notoriously difficult to detect (infact near nigh impossible) because of their weak nature. This looks like a good opportunity to do that.

Yes

[rebelcool]

Article

G Waves and other fun things to look for

[DumbSwede]

This is great scientific news, I would imagine astronomical observations should allow for accurate predictions of resultant gravity wave phenomenon. By knowing the time and amplitude of the gravity waves emanating, one should be able to calibrate and adust LIGO to a great deal of precision. I think till know we have been in a I-Duh-Know-Maybe-It's-Working state. Once we know LIGO is working, we will be able to finally detect gravitational phenomenon directly.

As an aside, with a system this unique, and not to sound too much like a loon, but perhaps we should look for an ET presence. Not as the creators, but there maybe unique physical process than can be exploited in such a system, and doing so may give off a detectable technological signature.

Actually not yet, but...

[UPAAntilles]

Here's a cool kid's site that has some animations

It's for the LISA (Laser Interferometer Space Antenna). Space.com did a story on it a little while back, and it was in a Scientific American, but I'm not sure which, I have too many lying around. Unfortunantly, it doesn't launch until 2009.

Re:Speed of Gravity

[sahrss]

You can also download the entire thing if you like. I just spent 15 minutes digging all this up, figured I might save someone else that time.
Some previous Slashdotters showed us how (first link is to the highest quality download).

I got it to work fine with this (remove the spaces!):
curl "http://a768.g.akamai.net/5/768/142/3f9e9589/1a1a1 afb6ae049ae214fc034aad839a91985ea187bea5786f362d84 1a61948bf2688f01f87fb6fdf0e7ceb61c22186fb/nova_eu_ 30[12-14]c[01-08]_mp4_300.mov" -o universe#1_#2.mov

Re:Speed of Gravity

[TexVex]

When calculating the orbits of celestial bodies, it is necessary to assume that gravity is instantaneous. When an object moves, its gravity appears to move with it instantly. The earth appears to orbit the Sun's present position rather than where the sun appears to be due to speed-of-light delay.

As I understand it, though, there are two ways to look at it. The Earth is approximately 8 light-minutes from the Sun. The Earth is either orbiting the Sun's actual position, or it's orbiting a point that would be about eight minutes in front of the Sun's extrapolated path based on its position and momentum at that given instant.

It comes down to a question of whether or not gravity is a field or a particle. If it's a particle, then it must travel at some unimaginable speed. If it's a field then it would share some of the properties (like velocity and direction) of the object that generates it, and changes to the field would propagate outward from the object at the speed of light. These changes to an object's field of gravity are thought to produce "gravity waves" that have yet to be detected.

I could very well be muddled on this subject but I have done some reading on it. Please correct me if I'm wrong.

gravity wave detection

[simonharvey]

there are at least two methods that I know off that can be used to detect the sign of gravity waves:

1. The first is to photograph the upper atmosphere with an incredibly sensitive camera during night time, the reason is that gravity waves (that have a period of a few hours) cause the upper atmosphere to strech and compress causing the atoms that cause air glow to seporate into layers. this shows up on the image as bands. these gravity waves are emitted from the center of the earth.
2. the second is to use an incredibly precise receiver tuned to a reliable transmitter in the HF bands, to a frequency that gets reflected by the ionosphere. since gravity waves will cause the ionosphere to expand and contract the change in velocity will cause the HF signal to be doppler shifted, meaning the gravity wave will be shown up in a slight variation of the incomming frequency.

the second option can be done by ham radio operators (if they really know there stuff), the first option is for universities since only they have the budget to buy the expensive equipment.

simon

Re:Speed of Gravity

[Effexor]

Yes, it is a rather confusing analogy. The way to look at it is that the sheet is space itself. Draw lines on it, and each of these is a straight line. Now when you place the object in it and it curves the sheet, notice that the 'straight' lines are now curved by it. This is analogous to the mass warping space. The lines are now curved, and the 'straight' path of an object on this curved space is now going to curve as well.

Now imagine it in 3D.